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Sample records for coal pyrite mechanisms

  1. Catalytic activity of pyrite for coal liquefaction reaction; Tennen pyrite no shokubai seino ni kansuru kento

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    Hirano, K.; Kozu, M.; Okada, T.; Kobayashi, M. [Nippon Coal Oil Co. Ltd., Tokyo (Japan)

    1996-10-28

    Since natural pyrite is easy to obtain and cheap as coal liquefaction catalyst, it is to be used for the 150 t/d scale NEDOL process bituminous coal liquefaction pilot plant. NEDO and NCOL have investigated the improvement of catalytic activity of pulverized natural pyrite for enhancing performance and economy of the NEDOL process. In this study, coal liquefaction tests were conducted using natural pyrite catalyst pulverized by dry-type bowl mill under nitrogen atmosphere. Mechanism of catalytic reaction of the natural pyrite was discussed from relations between properties of the catalyst and liquefaction product. The natural pyrite provided an activity to transfer gaseous hydrogen into the liquefaction product. It was considered that pulverized pyrite promotes the hydrogenation reaction of asphaltene because pulverization increases its contact rate with reactant and the amount of active points on its surface. It was inferred that catalytic activity of pyrite is affected greatly by the chemical state of Fe and S on its surface. 3 refs., 4 figs., 1 tab.

  2. Decomposition of pyrite and the interaction of pyrite with coal organic matrix in pyrolysis and hydropyrolysis

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    Chen, H.; Li, B.; Zhang, B. [Chinese Academy of Sciences, Taiyuan (China). State Key Lab. of Coal Conversion, Inst. of Coal Chemistry

    2000-10-01

    The thermal behaviour of pure pyrite was studied under nitrogen and hydrogen atmospheres in a pressurized thermal balance. The transfer of pyrite in coal during pyrolysis and hydropyrolysis was investigated in a fixed-bed reactor. The results suggest that the indigenous hydro-carbon with hydrogen donor ability in coal can promote the reduction of pyrite in pyrolysis. At low temperatures, organic sulfur removal is almost the same in pyrolysis and hydropyrolysis of two coals. It is likely that indigenous hydrogen in coal is the dominant factor in organic sulfur elimination in the low-temperature stage. An increase of organic sulfur in pyrolysis of Hongmiao coal indicates that the lack of the indigenous hydrogen may be the key factor determining the transformation of pyritic sulfur into organic sulfur. Oxygen affects the conversion of pyrite into organic sulfur through the competitive consumption of hydrogen. 12 refs., 5 figs., 1 tab.

  3. Waste pyritic coal as a raw material for energetic industry

    Energy Technology Data Exchange (ETDEWEB)

    Gasiorek, J. [Institute of Inorganic Chemistry, Poznan (Poland). Dept. of Research and Technology

    1997-11-01

    Results are presented of large laboratory studies on coal desulphurisation with foam flotation method improved by application of bioadsorption of Thiobacillus ferrooxidans bacteria to the modification of superficial properties of pyrite particulates from hydrophobic to hydrophillic ones. Results of coal desulfurization with and without bioadsorption have been compared. Bioadsorption improved pyritic sulfur removal by 30% (for coal from `Sierza mine`, coal size 0.3 to 0.102 mm, S pyritic content 1.69%) after 6-week adaptation of bacteria and 30 min of bioadsorption. Bacteria concentration in 5% water suspension of coal reached 22 {mu}g of biomass cm{sup -3}. 12 refs., 4 figs., 1 tab.

  4. Decomposition of pyrite and the interaction of pyrite with coal organic matrix in pyrolysis and hydropyrolysis

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    Chen, H.; Li, B.; Zhang, B. [Chinese Academy of Sciences, Taiyuan (China). Institute of Coal Chemistry

    1999-07-01

    The thermal decomposition and reduction behaviour of pure pyrite crystals were studied under nitrogen and hydrogen atmospheres. Decomposition of pyrite in coal during pyrolysis and hydropyrolysis, and the behaviour of organic sulphur, are discussed. Temperature and pressure effects are considered. 7 refs., 6 figs., 1 tab.

  5. Comparison Analysis of Coal Biodesulfurization and Coal's Pyrite Bioleaching with Acidithiobacillus ferrooxidans

    Science.gov (United States)

    Hong, Fen-Fen; He, Huan; Liu, Jin-Yan; Tao, Xiu-Xiang; Zheng, Lei; Zhao, Yi-Dong

    2013-01-01

    Acidithiobacillus ferrooxidans (A. ferrooxidans) was applied in coal biodesulfurization and coal's pyrite bioleaching. The result showed that A. ferrooxidans had significantly promoted the biodesulfurization of coal and bioleaching of coal's pyrite. After 16 days of processing, the total sulfur removal rate of coal was 50.6%, and among them the removal of pyritic sulfur was up to 69.9%. On the contrary, after 12 days of processing, the coal's pyrite bioleaching rate was 72.0%. SEM micrographs showed that the major pyrite forms in coal were massive and veinlets. It seems that the bacteria took priority to remove the massive pyrite. The sulfur relative contents analysis from XANES showed that the elemental sulfur (28.32%) and jarosite (18.99%) were accumulated in the biotreated residual coal. However, XRD and XANES spectra of residual pyrite indicated that the sulfur components were mainly composed of pyrite (49.34%) and elemental sulfur (50.72%) but no other sulfur contents were detected. Based on the present results, we speculated that the pyrite forms in coal might affect sulfur biooxidation process. PMID:24288464

  6. Semiconductor electrochemistry of coal pyrite. Final technical report, September 1990--September 1995

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    Osseo-Asare, K.; Wei, Dawei

    1996-01-01

    This project seeks to advance the fundamental understanding of the physico-chemical processes occurring at the pyrite/aqueous interface, in the context of coal cleaning, coal desulfurization, and acid mine drainage. Central to this research is the use of synthetic microsize particles of pyrite as model microelectrodes to investigate the semiconductor electrochemistry of pyrite. The research focuses on: (a) the synthesis of microsize particles of pyrite in aqueous solution at room temperature, (b) the formation of iron sulfide complex, the precursor of FeS or FeS{sub 2}, and (c) the relationship between the semiconductor properties of pyrite and its interfacial electrochemical behavior in the dissolution process. In Chapter 2, 3 and 4, a suitable protocol for preparing microsize particles of pyrite in aqueous solution is given, and the essential roles of the precursors elemental sulfur and ``FeS`` in pyrite formation are investigated. In Chapter 5, the formation of iron sulfide complex prior to the precipitation of FeS or FeS{sub 2} is investigated using a fast kinetics technique based on a stopped-flow spectrophotometer. The stoichiometry of the iron sulfide complex is determined, and the rate and formation constants are also evaluated. Chapter 6 provides a summary of the semiconductor properties of pyrite relevant to the present study. In Chapters 7 and 8, the effects of the semiconductor properties on pyrite dissolution are investigated experimentally and the mechanism of pyrite dissolution in acidic aqueous solution is examined. Finally, a summary of the conclusions from this study and suggestions for future research are presented in Chapter 9.

  7. Semiconductor electrochemistry of coal pyrite. Final technical report, September 1990--September 1995

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    Osseo-Asare, K.; Wei, D.

    1996-01-01

    This project is concerned with the physiochemical processes occuring at the pyrite/aqueous interface, in the context of coal cleaning, desulfurization, and acid mine drainage. The use of synthetic particles of pyrite as model electrodes to investigate the semiconductor electrochemistry of pyrite is employed.

  8. Comparison Analysis of Coal Biodesulfurization and Coal’s Pyrite Bioleaching with Acidithiobacillus ferrooxidans

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    Fen-Fen Hong

    2013-01-01

    Full Text Available Acidithiobacillus ferrooxidans (A. ferrooxidans was applied in coal biodesulfurization and coal’s pyrite bioleaching. The result showed that A. ferrooxidans had significantly promoted the biodesulfurization of coal and bioleaching of coal’s pyrite. After 16 days of processing, the total sulfur removal rate of coal was 50.6%, and among them the removal of pyritic sulfur was up to 69.9%. On the contrary, after 12 days of processing, the coal’s pyrite bioleaching rate was 72.0%. SEM micrographs showed that the major pyrite forms in coal were massive and veinlets. It seems that the bacteria took priority to remove the massive pyrite. The sulfur relative contents analysis from XANES showed that the elemental sulfur (28.32% and jarosite (18.99% were accumulated in the biotreated residual coal. However, XRD and XANES spectra of residual pyrite indicated that the sulfur components were mainly composed of pyrite (49.34% and elemental sulfur (50.72% but no other sulfur contents were detected. Based on the present results, we speculated that the pyrite forms in coal might affect sulfur biooxidation process.

  9. Thermal behaviors of mechanically activated pyrites by thermogravimetry (TG)

    International Nuclear Information System (INIS)

    Hu Huiping; Chen Qiyuan; Yin Zhoulan; Zhang Pingmin

    2003-01-01

    The thermal decompositions of mechanically activated and non-activated pyrites were studied by thermogravimetry (TG) at the heating rate of 10 K min -1 in argon. Results indicate that the initial temperature of thermal decomposition (T di ) in TG curves for mechanically activated pyrites decreases gradually with increasing the grinding time. The specific granulometric surface area (S G ), the structural disorder of mechanically activated pyrites were analyzed by X-ray diffraction laser particle size analyzer, and X-ray powder diffraction analysis (XRD), respectively. The results show that the S G of mechanically activated pyrites remains almost constant after a certain grinding time, and lattice distortions (ε) rise but the crystallite sizes (D) decrease with increasing the grinding time. All these results imply that the decrease of T di in TG curves of mechanically activated pyrites is mainly caused by the increase of lattice distortions ε and the decrease of the crystallite sizes D of mechanically activated pyrite with increasing the grinding time. The differences in the reactivity between non-activated and mechanically activated pyrites were observed using characterization of the products obtained from 1 h treatment of non-activated and mechanically activated pyrites at 713 K under inert atmosphere and characterization of non-activated and mechanically activated pyrites exposed to ambient air for a certain period

  10. Source and Enrichment of Toxic Elements in Coal Seams around Mafic Intrusions: Constraints from Pyrites in the Yuandian Coal Mine in Anhui, Eastern China

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    Yanfei An

    2018-04-01

    Full Text Available Pyrite, a mineral that can cause potential environmental issues in coal mining, is commonly found in coal seams around intrusions. In this paper, pyrites from the Yuandian Coal Mine (Huaibei Coalfield, Anhui, Eastern China were studied using SEM, Raman and LA-ICP-MS. The pyrite morphologic and geochemical data suggest that (1 four pyrite generations are present (framboidal sedimentary pyrites (Py I in the original coal, coarse-grained magmatic pyrites (Py II in the intruding diabase, fine-grained metamorphic pyrites (Py III in the intrusive contact aureole, and spheroid/vein hydrothermal pyrites (Py IV in the cokeite; and (2 concentrations of cobalt, nickel, arsenic, selenium, lead and copper in the metamorphic pyrites are much higher than the other pyrite generations. We propose that mafic magmatism is the main contributor of the toxic elements to the intrusion-related cokeite at Yuandian.

  11. Distribution of sulfur and pyrite in coal seams from Kutai Basin (East Kalimantan, Indonesia): Implications for paleoenvironmental conditions

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    Widodo, Sri [Department of Mining Engineering, Moslem University of Indonesia, Jln. Urip Sumoharjo, Makassar (Indonesia); Oschmann, Wolfgang [Institute of Geosciece, J.W. Goethe-University, Altenhoeferallee 1, D-60438 Frankfurt a.M. (Germany); Bechtel, Achim; Sachsenhofer, Reinhard F. [Department of Applied Geoscience and Geophysics, University of Leoben, Peter-Tunner-Str.5, A-8700 Leoben (Austria); Anggayana, Komang [Department of Mining Engineering, Bandung Institute of Technology, Jln. Ganesa 10, I-40132 Bandung (Indonesia); Puettmann, Wilhelm [Institute of Atmospheric and Environmental Sciences, Dapartment of Analytical Enviromental Chemistry, J.W. Goethe-University, Altenhoeferallee 1, D-60438 Frankfurt a.M. (Germany)

    2010-03-01

    Thirteen Miocene coal samples from three active open pit and underground coal mines in the Kutai Basin (East Kalimantan, Indonesia) were collected. According to our microscopical and geochemical investigations, coal samples from Sebulu and Centra Busang coal mines yield high sulfur and pyrite contents as compared to the Embalut coal mine. The latter being characterized by very low sulfur (< 1%) and pyrite contents. The ash, mineral, total sulfur, iron (Fe) and pyrite contents of most of the coal samples from the Sebulu and Centra Busang coal mines are high and positively related in these samples. Low contents of ash, mineral, total sulfur, iron (Fe) and pyrite have been found only in sample TNT-32 from Centra Busang coal mine. Pyrite was the only sulfur form that we could recognize under reflected light microscope (oil immersion). Pyrite occurred in the coal as framboidal, euhedral, massive, anhedral and epigenetic pyrite in cleats/fractures. High concentration of pyrite argues for the availability of iron (Fe) in the coal samples. Most coal samples from the Embalut coal mine show lower sulfur (< 1 wt.%) and pyrite contents as found within Centra Busang and Sebulu coals. One exception is the coal sample KTD-38 from Embalut mine with total sulfur content of 1.41 wt.%. The rich ash, mineral, sulfur and pyrite contents of coals in the Kutai Basin (especially Centra Busang and Sebulu coals) can be related to the volcanic activity (Nyaan volcanic) during Tertiary whereby aeolian material was transported to the mire during or after the peatification process. Moreover, the adjacent early Tertiary deep marine sediment, mafic igneous rocks and melange in the center of Kalimantan Island might have provided mineral to the coal by uplift and erosion. The inorganic matter in the mire might also originate from the ground and surface water from the highland of central Kalimantan. (author)

  12. A dynamic mathematical model for microbial removal of pyritic sulfur from coal.

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    Kargi, F; Weissman, J G

    1984-06-01

    A dynamic mathematical model has been developed to describe microbial desulfurization of coal by Thiobacillus ferrooxidans. The model considers adsorption and desorption of cells on coal particles and microbial oxidation of pyritic sulfur on particle surfaces. The influence of certain parameters, such as microbial growth rate constants, adsorption-description constants, pulp density, coal particle size, initial cell and solid phase substrate concentration on the maximum rate of pyritic sulfur removal, have been elucidated. The maximum rate of pyritic sulfur removal was strongly dependent upon the number of attached cells per coal particle. At sufficiently high initial cell concentrations, the surfaces of coal particles are nearly saturated by the cells and the maximum leaching rate is limited either by total external surface area of coal particles or by the concentration of pyritic sulfur in the coal phase. The maximum volumetric rate of pyritic sulfur removal (mg S/h cm(3) mixture) increases with the pulp density of coal and reaches a saturation level at high pulp densities (e.g. 45%). The maximum rate also increases with decreasing particle diameter in a hyperbolic form. Increases in adsorption coefficient or decreases in the desorption coefficient also result in considerable improvements in this rate. The model can be applied to other systems consisting of suspended solid substrate particles in liquid medium with microbial oxidation occurring on the particle surfaces (e.g., bacterial ore leaching). The results obtained from this model are in good agreement with published experimental data on microbial desulfurization of coal and bacterial ore leaching.

  13. Use of the Moessbauer effect for determining pyritic sulfur content in coal

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    Czerw, B; Sikora, T

    1986-10-01

    This paper discusses investigations into resonance absorption of gamma radiation. Standard equipment for measuring the Moessbauer effect in black coal consisting of a measuring head, the SM-4T spectrometer, a multichannel analyzer, the Standard electronic unit and a printer is evaluated. The MSP measuring system developed jointly by the EMAG Mine Automation Company and the Nuclear Research Institute in Swierk is described. The MSP equipment is used for measuring content of pyritic sulfur in coal. Its accuracy is satisfactory. Results of measuring pyritic and total sulfur content by means of quantitative chemical analysis and by the MSP resonance absorption method (Moessbauer effect) are compared. The mean standard deviation for pyritic sulfur is 0.14% and for total sulfur content 0.21%. 11 refs.

  14. Reaction mechanism of coal liquefaction: hydrogenolysis of model compound using synthetic pyrite as catalysts. 7. Property change of synthetic pyrite catalyst with the time after production; Sekitan ekika hanno kiko (model kagobutsu no hanno). 7. Gosei ryukatetsu shokubai no keiji henka ni tsuite

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    Ito, H.; Meno, H.; Uemaki, O.; Shibata, T.; Tsuji, T. [Hokkaido University, Sapporo (Japan)

    1996-10-28

    Reactions of various model compounds were investigated using synthetic pyrites for coal liquefaction. In this study, successive changes of the catalysts were investigated from the reactions of model compounds by using three different synthetic pyrites with the lapse of time after production. Benzyl phenyl ether, dibenzyl, and n-octylbenzene were used as model compounds. Reactions were conducted in an autoclave, into which sample, catalyst, decalin as solvent, and initial hydrogen pressure 10 MPa were charged. The autoclave was held at 450 or 475{degree}C of reaction temperature for 1 hour. The catalyst with a shorter lapse of time after production acted to hydrogen transfer, and inhibited the formation of condensation products due to the stabilization of decomposed fragment. It also acted to isomerization of materials by cutting alkyl side chains. When adding sulfur to the catalyst with longer lapse of time after production under these reaction conditions, it inhibited the formation of condensation products for the reaction of benzyl phenyl ether. However, it did not provide the effect for the reaction of n-octylbenzene. 5 refs., 3 figs.

  15. Calorimetric investigation on mechanically activated storage energy mechanism of sphalerite and pyrite

    International Nuclear Information System (INIS)

    Xiao Zhongliang; Chen Qiyuan; Yin Zhoulan; Hu Huiping; Wu Daoxin

    2005-01-01

    The structural changes of mechanically activated sphalerite and pyrite under different grinding conditions were determined by X-ray powder diffraction (XRD), laser particle size analyzer and elemental analysis. The storage energy of mechanically activated sphalerite and pyrite was measured by a calorimetric method. A thermochemical cycle was designed so that mechanically activated and non-activated minerals reached the same final state when dissolved in the same oxidizing solvent. The results show that the storage energy of mechanically activated sphalerite and pyrite rises with increased in grinding time, and reaches a maximum after a certain grinding period. The storage energy of mechanically activated pyrite decreases when heated under inert atmosphere. The storage energy of mechanically activated sphalerite and pyrite remains constant when treated below 573 K under inert atmosphere. The percentage of the storage energy caused by surface area increase during mechanical activation decreases with increasing grinding time. These results support our opinion that the mechanically activated storage energy of sphalerite is closely related to lattice distortions, and the mechanically activated storage energy of pyrite is mainly caused by the formation of reactive sites on the surface

  16. Oxidation of pyrite: Consequences and significance

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    Dimitrijević Mile D.

    2002-01-01

    Full Text Available This paper presents the most important studies on the oxidation of pyrite particularly in aqueous solutions. The consequences of pyrite oxidation was examined, as well as its importance, from both the technical-technological and environmental points of view. The oxidation of pyrite was considered in two parts. The spontaneous oxidation of pyrite in nature was described in the first part, with this part comprising pyrite oxidation in deposits depots and mines. It is explained how way natural electrochemical processes lead to the decomposition of pyrite and other minerals associated with pyrite. The oxidation of pyrite occurring during technological processes such as grinding, flotation and leaching, was shown in the second part. Particular emphasis was placed on the oxidation of pyrite during leaching. This part includes the leaching of sulphide and oxide ores, the leaching of pyrite coal and the leaching of refractory gold-bearing ores (pressure oxidation, bacterial oxidation, oxidation by means of strong oxidants and the electrolysis of pyrite suspensions. Various mechanisms of pyrite oxidation and of the galvanic interaction of pyrite with other sulphide minerals are shown.

  17. Mössbauer study of the effect of gamma irradiation on the removal of pyrite from Colombian coals

    International Nuclear Information System (INIS)

    Mejía, J A; Palacio, C A; Caballero, F Reyes; Dávila, H Olaya; Ovalle, S A Martínez; De Grave, E

    2014-01-01

    The removal of sulfur from the coals is necessary before using it. It is due to the environmental and technological problems that it causes. In this work, the results of the study by Mössbauer spectroscopy of the gamma-irradiation effect on the pyrite in three Colombian coals are analyzed. They were exposed to different gamma-irradiation doses using a 60 Co source

  18. Mechanisms of interaction between arsenian pyrite and aqueous arsenite under anoxic and oxic conditions

    Science.gov (United States)

    Qiu, Guohong; Gao, Tianyu; Hong, Jun; Luo, Yao; Liu, Lihu; Tan, Wenfeng; Liu, Fan

    2018-05-01

    Pyrite affects the conversion and migration processes of arsenic in soils and waters. Adsorption and redox reactions of arsenite (As(III)) occur on the surface of pyrite, and the interaction processes are influenced by the arsenic incorporated into pyrite. This work examined the effects of arsenic content, pH and oxygen on the interaction between arsenian pyrite and aqueous As(III) and investigated the underlying mechanisms. The results indicated that arsenic incorporation led to a high content of Fe(III) in pyrite, and that As(III) was mainly adsorbed on pyrite surface and part of As(III) was oxidized to As(V) by the newly formed intermediates including hydroxyl radicals and hydrogen peroxide. The oxidation rate increased with increasing arsenic content in the pyrite and the presence of air (oxygen), and first decreased and then increased with increasing pH from 3.0 to 11.0. Hydroxyl radicals and hydrogen peroxide significantly contributed to the oxidation of pyrite and aqueous As(III) in acidic and alkaline solutions, respectively. Although pyrite oxidation increased with increasing arsenic content as indicated by the elevated concentrations of elemental S and SO42-, the percentage of released arsenic in total arsenic of the arsenian pyrite decreased due to the adsorption of arsenic on the surface of newly formed ferric (hydr)oxides, especially the ferric arsenate precipitate formed in high pH solutions. The present study enables a better understanding of the important interaction process of dissolved arsenite and natural pyrites in the study of groundwater contamination, arsenic migration/sequestration, and acid mine drainage formation.

  19. The mechanisms of pyrite oxidation and leaching: A fundamental perspective

    Science.gov (United States)

    Chandra, A. P.; Gerson, A. R.

    2010-09-01

    Pyrite is the earth's most abundant sulfide mineral. Its frequent undesirable association with minerals of economic value such as sphalerite, chalcopyrite and galena, and precious metals such as gold necessitates costly separation processes such as leaching and flotation. Additionally pyrite oxidation is a major contributor to the environmental problem of acid rock drainage. The surface oxidation reactions of pyrite are therefore important both economically and environmentally. Significant variations in electrical properties resulting from lattice substitution of minor and trace elements into the lattice structure exist between pyrite from different geographical locations. Furthermore the presence of low coordination surface sites as a result of conchoidal fracture causes a reduction in the band gap at the surface compared to the bulk thus adding further electrochemical variability. Given the now general acceptance after decades of research that electrochemistry dominates the oxidation process, the geographical location, elemental composition and semi-conductor type (n or p) of pyrite are important considerations. Aqueous pyrite oxidation results in the production of sulfate and ferrous iron. However other products such as elemental sulfur, polysulfides, hydrogen sulfide, ferric hydroxide, iron oxide and iron(III) oxyhydroxide may also form. Intermediate species such as thiosulfate, sulfite and polythionates are also proposed to occur. Oxidation and leach rates are generally influenced by solution Eh, pH, oxidant type and concentration, hydrodynamics, grain size and surface area in relation to solution volume, temperature and pressure. Of these, solution Eh is most critical as expected for an electrochemically controlled process, and directly correlates with surface area normalised rates. Studies using mixed mineral systems further indicate the importance of electrochemical processes during the oxidation process. Spatially resolved surface characterisation of fresh

  20. Flocculation of Pyrite Fines in Aqueous Suspensions with Corn Starch to Eliminate Mechanical Entrainment in Flotation

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    Wei Ge

    2015-10-01

    Full Text Available The hydrophilic flocculation of pyrite fines in aqueous suspensions with corn starch was studied by measuring particle size distribution, microscopy observation and micro-flotation. Furthermore, the interaction of corn starch with pyrite was investigated by determining the adsorption density and based on zeta potential measurements and X-ray photoelectron spectrometer (XPS analysis in this work. The results of the particle size distribution measurement show that corn starch can effectively aggregate pyrite fines, and the pyrite floccules (flocs are sensitive to mechanical stirring. The micro-flotation results suggest that the mechanical entrainment of pyrite fines in flotation can be effectively eliminated through the formation of large-size flocs. The zeta potential of pyrite particles decreases with the addition of corn starch. The XPS results prove that carboxyl groups are generated on the digested corn starch, and both iron hydroxyl compounds and ferrous disulfide on the pyrite surface can chemically interact with the corn starch digested by sodium hydroxide.

  1. Report on assessment of the mechanism of bacterially assisted oxidation of pyritic uranium tailings

    International Nuclear Information System (INIS)

    Halbert, B.B.; Scharer, J.M.; Knapp, R.A.

    1984-07-01

    The oxidation of pyritic minerals has been shown to be catalyzed by the presence of iron- and sulphur-oxidizing bacteria. Thiobacillus ferroxidans plays the most significant role in the formation and propagation of acidic conditions. Optimum growth conditions for the T. ferroxidans occurs at a temperature of 35 degrees C and pH of 2 to 3. Bacterially assisted oxidation of pyrite involves both direct and indirect contact mechanisms. The direct contact mechanism entails enzymatic oxidation of the insoluble sulphide moiety. The indirect mechanism involves bacterial oxidation of the dissolved ferrous component to the ferric state. The ferric iron, in turn, acts as the prime oxidant of pyrite and is reduced to ferrous iron. The re-oxidation of the dissolved ferrous component which is catalyzed by bacterial activity, completes the cyclic process. The rate of bacterial oxidation is affected by: the geochemistry and reactivity of the pyritic material; the amount of pyrite present in the waste material and the exposed surface area of the pyritic component; the availability of oxygen and carbon dioxide; the pH and temperature of the leach solution; and the presence (or absence) of organic inhibitors. Of the above factors, oxygen has been frequently identified as the rate limiting reactant in tailings

  2. Investigation of pyrite as a contributor to slagging in eastern bituminous coals. Quarterly progress report 9, October 1-December 31, 1983

    Energy Technology Data Exchange (ETDEWEB)

    Bryers, R.W.

    1984-06-01

    The objective of this program is to examine slags formed as a result of firing coals with varying concentration levels, size distribution, and orientation of pyrite with regard to mineral matter in the coal in a laboratory furnace. The program tasks are: (1) selection of eight candidate coals; (2) chemical characterization of the coal samples and identification of the pyrite size, distribution, and orientation with respect to other mineral matter and concentration levels; (3) testing of the candidate coals in a laboratory furnace; (4) chemical and physical characterization of the slag and fly ash samples created by the impurities in the coal sample; (5) influence of coal beneficiation on furnace slagging; and (6) analysis of data and identification of parameters influencing the contribution of pyrite to slagging problems. Washing of the Upper Freeport coal from Indiana County, Pennsylvania, was completed by the last quarter of 1983. The washed product was characterized for mineral content, and a combustion test was performed. Kentucky No. 9 from Henderson County, Kentucky, selected as the sixth coal to be investigated, was characterized using size and gravity fractionation techniques and was combusted in the laboratory furnace to evaluate its slagging and fouling potential. The remaining two coals to be characterized and combusted were identified as Illinois No. 5 and Lower Kittanning from Clarion County, Pennsylvania. 80 figures, 27 tables.

  3. On the mechanism of action of combination of thionocarbamates with xanthate during flotation of copper-molybdenum pyrite contained ores

    International Nuclear Information System (INIS)

    Nedosekina, T.V.; Glembotskij, A.V.; Bekhtle, G.A.; Novgorodova, Eh.Z.

    1985-01-01

    Investigation results of action mechanism of thionocarbamates combination with xanthate are described. It is established that these collectors are capable of co-adsorbing on pyrite surface, that is the reason for sharp increase of the floatability and disturbs the selectivity of copper-molybdenum pyrite-containing ore flotation

  4. Pyrite thermochemistry, ash agglomeration, and char fragmentation during pulverized coal combustion. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Akan-Etuk, A.; Diaz, R.; Niksa, S.

    1991-10-01

    The objective of the present work is to introduce an experimental program that will eventually lead to time-resolved iron ash composition over the technological operating domain. The preceding literature survey suggests two important stipulations on any such experimental program. The first stipulation is that good control must be established over the operating conditions, to accurately quantify their effects. The other is that data must be obtained rapidly, to thoroughly cover the important operating domain. This work presents a series of studies that has characterized the desulfurization of pyrite during the early stages of combustion. An experimental system was established and used to monitor the effects of oxygen, temperature, and residence time on the evolution of condensed phase products of the combustion of pure pyrite. (VC)

  5. Pyrite thermochemistry, ash agglomeration, and char fragmentation during pulverized coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Akan-Etuk, A.; Diaz, R.; Niksa, S.

    1991-10-01

    The objective of the present work is to introduce an experimental program that will eventually lead to time-resolved iron ash composition over the technological operating domain. The preceding literature survey suggests two important stipulations on any such experimental program. The first stipulation is that good control must be established over the operating conditions, to accurately quantify their effects. The other is that data must be obtained rapidly, to thoroughly cover the important operating domain. This work presents a series of studies that has characterized the desulfurization of pyrite during the early stages of combustion. An experimental system was established and used to monitor the effects of oxygen, temperature, and residence time on the evolution of condensed phase products of the combustion of pure pyrite. (VC)

  6. Study of mechanically activated coal combustion

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    Burdukov Anatolij P.

    2009-01-01

    Full Text Available Combustion and air gasification of mechanically activated micro-ground coals in the flux have been studied. Influence of mechanically activated methods at coals grinding on their chemical activeness at combustion and gasification has been determined. Intense mechanical activation of coals increases their chemical activeness that enables development of new highly boosted processing methods for coals with various levels of metamorphism.

  7. Surface structure-dependent pyrite oxidation in relatively dry and moist air: Implications for the reaction mechanism and sulfur evolution

    Science.gov (United States)

    Zhu, Jianxi; Xian, Haiyang; Lin, Xiaoju; Tang, Hongmei; Du, Runxiang; Yang, Yiping; Zhu, Runliang; Liang, Xiaoliang; Wei, Jingming; Teng, H. Henry; He, Hongping

    2018-05-01

    Pyrite oxidation not only is environmentally significant in the formation of acid mine (or acid rock) drainage and oxidative acidification of lacustrine sediment but also is a critical stage in geochemical sulfur evolution. The oxidation process is always controlled by the reactivity of pyrite, which in turn is controlled by its surface structure. In this study, the oxidation behavior of naturally existing {1 0 0}, {1 1 1}, and {2 1 0} facets of pyrite was investigated using a comprehensive approach combining X-ray photoelectron spectroscopy, diffuse reflectance Fourier transform infrared spectroscopy, and time-of-flight secondary-ion mass spectrometry with periodic density functional theoretical (DFT) calculations. The experimental results show that (i) the initial oxidation rates of both pyrite {1 1 1} and {2 1 0} are much greater than that of pyrite {1 0 0}; (ii) the initial oxidation rate of pyrite {2 1 0} is greater than that of pyrite {1 1 1} in low relative humidity, which is reversed in high relative humidity; and (iii) inner sphere oxygen-bearing sulfur species are originally generated from surface reactions and then converted to outer sphere species. The facet dependent rate law can be expressed as: r{hkl} =k{hkl}haP0.5(t + 1) - 0.5 , where r{hkl} is the orientation dependent reaction rate, k{hkl} is the orientation dependent rate constant, h is the relative humidity, P is the oxygen partial pressure, and t is the oxidation time in seconds. {1 1 1} is the most sensitive facet for pyrite oxidation. Combined with DFT theoretical investigations, water catalyzed electron transfer is speculated as the rate-limiting step. These findings disclose the structure-reactivity dependence of pyrite, which not only presents new insight into the mechanism of pyrite oxidation but also provides fundamental data to evaluate sulfur speciation evolution, suggesting that the surface structure sensitivity should be considered to estimate the reactivity at the mineral

  8. Presentation on mechanisms and applications of chalcopyrite and pyrite bioleaching in biohydrometallurgy - a presentation.

    Science.gov (United States)

    Tao, Huang; Dongwei, Li

    2014-12-01

    This review outlines classic and current research, scientific documents and research achievements in bioleaching, particularly in respect of the bioleaching of chalcopyrite and pyrite. The diversity and commonality of the microbial leaching process can be easily studied through comparing the bioleaching mechanism and the application of these two metal sulfides. The crystal, electronic and surface structures of chalcopyrite and pyrite are summarized in detail in this paper. It determines the specific and complicated interaction pathways, kinetics of the atmospheric/aqueous oxidation, and the control process of bioleaching of the minerals as the precondition. Bioleaching of metal sulfides is performed by a diverse group of microorganisms and microbial communities. The species of the bacteria which have a significant effect on leaching ores are miraculously diverse. The newly identified acidophilic microorganisms with unique characteristics for efficient bioleaching of sulfidic minerals are increasing sharply. The cell-to-cell communication mechanisms, which are still implicit, elusive and intangible at present day, have gradually become a research hotspot. The different mineralogy characteristics and the acid solubility of the metal sulfides (e.g., chalcopyrite and pyrite) cause two different dissolution pathways, the thiosulfate and the polysulfide pathways. The bioleaching mechanisms are categorized by contact (an electrostatic attachment) and noncontact (planktonic) process, with emphasis on the produce of extracellular polymeric substances and formation of biofilm on the surface of the metal sulfides in this paper. The division of the direct and indirect effect are not adopted due to the redox chain, the reduction of the ferric iron and oxidation of the ferrous iron. The molecular oxygen is reduced by the electrons extracted from the specific metal sulfide, via a redox chain forming a supercomplex spanning the periplasmic space and connecting both outer and inner

  9. Thermal stability and mechanism of decomposition of emulsion explosives in the presence of pyrite

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhi-Xiang; Wang, Qian [School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013 (China); Fu, Xiao-Qi, E-mail: xzx19820708@163.com [School of Chemistry and Chemical Engineering, Jiangsu University Zhenjiang 212013 (China)

    2015-12-30

    Highlights: • An exothermic reaction occurs at about 200 °C between pyrite and ammonium nitrate (emulsion explosives). • The essence of reaction between emulsion explosives and pyrite is reaction between ammonium nitrate and pyrite. • The excellent thermal stability of emulsion explosives does not mean it was also showed when pyrite was added. • A new overall reaction has been proposed as: • 14FeS{sub 2}(s) + 91NH{sub 4}NO{sub 3}(s) → 52NO(g) + 26SO{sub 2}(g) + 6Fe{sub 2}O{sub 3}(s) + 78NH{sub 3}(g) + 26N{sub 2}O(g) + 2FeSO{sub 4}(s) + 65H{sub 2}O(g). - Abstract: The reaction of emulsion explosives (ammonium nitrate) with pyrite was studied using techniques of TG-DTG-DTA. TG–DSC–MS was also used to analyze samples thermal decomposition process. When a mixture of pyrite and emulsion explosives was heated at a constant heating rate of 10 K/min from room temperature to 350 °C, exothermic reactions occurred at about 200 °C. The essence of reaction between emulsion explosives and pyrite is the reaction between ammonium nitrate and pyrite. Emulsion explosives have excellent thermal stability but it does not mean it showed the same excellent thermal stability when pyrite was added. Package emulsion explosives were more suitable to use in pyrite shale than bulk emulsion explosives. The exothermic reaction was considered to take place between ammonium nitrate and pyrite where NO, NO{sub 2}, NH{sub 3}, SO{sub 2} and N{sub 2}O gases were produced. Based on the analysis of the gaseous, a new overall reaction was proposed, which was thermodynamically favorable. The results have significant implication in the understanding of stability of emulsion explosives in reactive mining grounds containing pyrite minerals.

  10. Thermal stability and mechanism of decomposition of emulsion explosives in the presence of pyrite

    International Nuclear Information System (INIS)

    Xu, Zhi-Xiang; Wang, Qian; Fu, Xiao-Qi

    2015-01-01

    Highlights: • An exothermic reaction occurs at about 200 °C between pyrite and ammonium nitrate (emulsion explosives). • The essence of reaction between emulsion explosives and pyrite is reaction between ammonium nitrate and pyrite. • The excellent thermal stability of emulsion explosives does not mean it was also showed when pyrite was added. • A new overall reaction has been proposed as: • 14FeS_2(s) + 91NH_4NO_3(s) → 52NO(g) + 26SO_2(g) + 6Fe_2O_3(s) + 78NH_3(g) + 26N_2O(g) + 2FeSO_4(s) + 65H_2O(g). - Abstract: The reaction of emulsion explosives (ammonium nitrate) with pyrite was studied using techniques of TG-DTG-DTA. TG–DSC–MS was also used to analyze samples thermal decomposition process. When a mixture of pyrite and emulsion explosives was heated at a constant heating rate of 10 K/min from room temperature to 350 °C, exothermic reactions occurred at about 200 °C. The essence of reaction between emulsion explosives and pyrite is the reaction between ammonium nitrate and pyrite. Emulsion explosives have excellent thermal stability but it does not mean it showed the same excellent thermal stability when pyrite was added. Package emulsion explosives were more suitable to use in pyrite shale than bulk emulsion explosives. The exothermic reaction was considered to take place between ammonium nitrate and pyrite where NO, NO_2, NH_3, SO_2 and N_2O gases were produced. Based on the analysis of the gaseous, a new overall reaction was proposed, which was thermodynamically favorable. The results have significant implication in the understanding of stability of emulsion explosives in reactive mining grounds containing pyrite minerals.

  11. Thermal stability and mechanism of decomposition of emulsion explosives in the presence of pyrite.

    Science.gov (United States)

    Xu, Zhi-Xiang; Wang, Qian; Fu, Xiao-Qi

    2015-12-30

    The reaction of emulsion explosives (ammonium nitrate) with pyrite was studied using techniques of TG-DTG-DTA. TG-DSC-MS was also used to analyze samples thermal decomposition process. When a mixture of pyrite and emulsion explosives was heated at a constant heating rate of 10K/min from room temperature to 350°C, exothermic reactions occurred at about 200°C. The essence of reaction between emulsion explosives and pyrite is the reaction between ammonium nitrate and pyrite. Emulsion explosives have excellent thermal stability but it does not mean it showed the same excellent thermal stability when pyrite was added. Package emulsion explosives were more suitable to use in pyrite shale than bulk emulsion explosives. The exothermic reaction was considered to take place between ammonium nitrate and pyrite where NO, NO2, NH3, SO2 and N2O gases were produced. Based on the analysis of the gaseous, a new overall reaction was proposed, which was thermodynamically favorable. The results have significant implication in the understanding of stability of emulsion explosives in reactive mining grounds containing pyrite minerals. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Review biodepyritisation of coal

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, C.; Sukla, L.B.; Misra, V.N. [Regional Research Lab., Orissa (India)

    2004-01-01

    This review provides a detailed summary of the recent and past research activities in the area of biodesulfurisation of coal. It provides information about microorganisms important for biodesulfurisation of coal, with the emphasis on Thiobacillus ferrooxidans. The review presents an insight into various methods of desulfurisation of coal combining physical and biological methods. Also, there are discussions on coal structure, distribution, mechanism and kinetics of pyrite oxidation and jarosite precipitation. Finally, areas requiring further research are identified.

  13. Oxidation of coals in the course of mechanical treatment

    Energy Technology Data Exchange (ETDEWEB)

    A.G. Proidakov; G.A. Kalabin [Irkutsk State University, Irkutsk (Russian Federation)

    2009-04-15

    The results of a study of coal oxidation under stationary conditions and during mechanical treatment are presented. A considerable increase in the reaction rate constants of coal oxidation during mechanical treatment because of oxidative mechanical degradation was found.

  14. Pyritic waste from precombustion coal cleaning: Amelioration with oil shale retort waste and sewage sludge for growth of soya beans

    International Nuclear Information System (INIS)

    Lewis, B.G.; Gnanapragasam, N.; Stevens, M.L.

    1994-01-01

    Solid residue from fossil fuel mining and utilization generally present little hazard to human health. However, because of the high volumes generated, they do pose unique disposal problems in terms of land use and potential degradation of soil and water. In the specific case of wastes from precombustion coal cleaning, the materials include sulfur compounds that undergo oxidation when exposed to normal atmospheric conditions and microbial action and then produce sulfuric acid. The wastes also contain compounds of metals and nonmetals at concentrations many times those present in the original raw coal. Additionally, the residues often contain coal particles and fragments that combust spontaneously if left exposed to the air, thus contributing to the air pollution that the coal cleaning process was designed to prevent. Federal and state efforts in the United States to ameliorate the thousands of hectares covered with these wastes have focused on neutralizing the acidity with limestone and covering the material with soil. The latter procedure creates additional degraded areas, which were originally farmland or wildlife habitat. It would seem preferable to reclaim the coal refuse areas without earth moving. The authors describe here experiments with neutralization of coal waste acidity using an alkaline waste derived from the extraction of oil from oil shale to grow soya beans (Glycine max. [L]) on a mixture of wastes and sewage sludge. Yield of plant material and content of nutrients an potentially toxic elements in the vegetation and in the growth mixtures were determined; results were compared with those for plants grown on an agricultural soil, with particular focus on boron

  15. The use of mixed pyrrhotite/pyrite catalysts for co-liquefaction of coal and waste rubber tires

    Energy Technology Data Exchange (ETDEWEB)

    Dadyburjor, D.B.; Zondlo, J.W.; Sharma, R.K. [West Virginia Univ., Morgantown, WV (United States)] [and others

    1995-12-31

    The overall objective of this research program is to determine the optimum processing conditions for tire/coal co-liquefaction. The catalysts used will be a ferric-sulfide-based materials, as well as promising catalysts from other consortium laboratories. The intent here is to achieve the maximum coal+tire conversion at the mildest conditions of temperature and pressure. Specific objectives include an investigation of the effects of time, temperature, pressure, catalyst and co-solvent on the conversion and product slate of the co-liquefaction. Accomplishments and conclusions are discussed.

  16. The migration law of overlay rock and coal in deeply inclined coal seam with fully mechanized top coal caving.

    Science.gov (United States)

    Liu, Jian; Chen, Shan-Le; Wang, Hua-Jun; Li, Yu-Cheng; Geng, Xiaowei

    2015-07-01

    In a mine area, some environment geotechnics problems always occure, induced by mined-out region such as the subsidence and cracks at ground level, deformation and destruction of buildings, landslides destruction of water resources and the ecological environment. In order to research the migration of surrounding rock and coal in steeply inclined super high seams which used fully mechanized top coal caving, a working face of a certain mine was made as an example, analyzed the migration law of the overlay rock and coal under different caving ratio of fully mechanized top coal caving with numerical simulation analysis. The results suggest that the laws of overlay rock deformation caused by deeply inclined coal seam were different from horizontal coal seam. On the inclined direction, with an increase of dip angle and caving ratio, the vertical displacement of overlay rock and coal became greater, the asymmetric phenomenon of vertical displacement became obvious. On the trend direction, active region and transition region in goaf became smaller along with the increase of mining and caving ratio. On the contrary, the stable region area became greater. Therefore, there was an essential difference between the mechanism of surface movement deformation with deeply inclined coal seam and that with horizontal coal seam.

  17. The Effect of Bedding Structure on Mechanical Property of Coal

    Directory of Open Access Journals (Sweden)

    Zetian Zhang

    2014-01-01

    Full Text Available The mechanical property of coal, influencing mining activity considerably, is significantly determined by the natural fracture distributed within coal mass. In order to study the effecting mechanism of bedding structure on mechanical property of coal, a series of uniaxial compression tests and mesoscopic tests have been conducted. The experimental results show that the distribution characteristic of calcite particles, which significantly influences the growth of cracks and the macroscopic mechanical properties of coal, is obviously affected by the bedding structure. Specifically, the uniaxial compression strength of coal sample is mainly controlled by bedding structure, and the average peak stress of specimens with axes perpendicular to the bedding planes is 20.00 MPa, which is 2.88 times the average amount of parallel ones. The test results also show a close relationship between the bedding structure and the whole deformation process under uniaxial loading.

  18. Thermal decomposition of pyrite

    International Nuclear Information System (INIS)

    Music, S.; Ristic, M.; Popovic, S.

    1992-01-01

    Thermal decomposition of natural pyrite (cubic, FeS 2 ) has been investigated using X-ray diffraction and 57 Fe Moessbauer spectroscopy. X-ray diffraction analysis of pyrite ore from different sources showed the presence of associated minerals, such as quartz, szomolnokite, stilbite or stellerite, micas and hematite. Hematite, maghemite and pyrrhotite were detected as thermal decomposition products of natural pyrite. The phase composition of the thermal decomposition products depends on the terature, time of heating and starting size of pyrite chrystals. Hematite is the end product of the thermal decomposition of natural pyrite. (author) 24 refs.; 6 figs.; 2 tabs

  19. Use of hard coal tailings for landfill construction with particular consideration to pyrite decay and to suitability of tailings as a geochemical barrier; Die Verwendung von Steinkohlebergematerialien im Deponiebau im Hinblick auf die Pyritverwitterung und die Eignung als geochemische Barriere

    Energy Technology Data Exchange (ETDEWEB)

    Schuering, J.

    1996-10-01

    The purpose of the present paper was to determine the hazard potential of acid formation during oxidation of the pyrite naturally contained in hard coal tailings and the efficacy of such tailings as a barrier against pollutants. The results were intended to show to what extent tailings can be recycled as a valuable material. This would not only offer an alternative to the land-consuming practice of dumping, which upon exhaustion of buffering capacity also gives rise to the problems associated with acid pit water, but would also allow the conservation of natural resources otherwise consumed in the sealing of landfills. (orig./HS) [Deutsch] Ziel dieser Arbeit war zum einen die Erfassung des Gefaehrdungspotentials durch die Saeurebildung bei der Oxidation des geogen im Bergmaterial enthaltenen Pyrits und zum anderen die Wirksamkeit als Barriere gegenueber Schadstoffen. Die Ergebnisse sollten aufzeigen, inwieweit das Bergematerial als Werkstoff eine weitere Verwendung finden kann. Von Bedeutung ist dabei nicht nur die Alternative zur flaechenintensiven Aufhaldung und den, bei Erschoepfung der Pufferkapazitaet, unter Umstaenden verbundenen Problemen bei der Bildung Saurer Grubenwaesser, sondern auch die Schonung natuerlicher Ressourcen bei der Verwendung in Deponieabdichtungen. (orig./HS)

  20. Research on Double Price Regulations and Peak Shaving Reserve Mechanism in Coal-Electricity Supply Chain

    Directory of Open Access Journals (Sweden)

    Hongjun Peng

    2013-01-01

    Full Text Available The game models were used to study the mechanism of coal-electricity price conflict under conditions of double price regulations of coal and electricity. Based on this, the peak shaving reserve mechanism was designed to probe into the countermeasures against the coal-electricity price conflicts. The study revealed that in the boom seasons of coal demand, the initiatives of the coal enterprises to supply thermal coal and the electricity enterprises to order thermal coal are reduced under conditions of double price regulations. However, under the circumstances of coal price marketization, in the boom seasons of coal demand the thermal coal price may go up obviously, the initiatives of the coal enterprises to supply thermal coal are increased, and meanwhile the initiatives of the power enterprises to order thermal coal are decreased dramatically. The transportation capacity constraint of coal supply leads to the evident decrease of the initiatives of coal enterprises for the thermal coal supply. The mechanism of peak shaving reserve of thermal coal may not only reduce the price of coal market but also increase the enthusiasm of the power enterprises to order more thermal coal and the initiatives of the coal enterprises to supply more thermal coal.

  1. Pyrite oxidation at circumneutral pH

    Science.gov (United States)

    Moses, Carl O.; Herman, Janet S.

    1991-02-01

    Previous studies of pyrite oxidation kinetics have concentrated primarily on the reaction at low pH, where Fe(III) has been assumed to be the dominant oxidant. Studies at circumneutral pH, necessitated by effective pH buffering in some pyrite oxidation systems, have often implicitly assumed that the dominant oxidant must be dissolved oxygen (DO), owing to the diminished solubility of Fe(III). In fact, Fe(III)(aq) is an effective pyrite oxidant at circumneutral pH, but the reaction cannot be sustained in the absence of DO. The purpose of this experimental study was to ascertain the relative roles of Fe(III) and DO in pyrite oxidation at circumneutral pH. The rate of pyrite oxidation was first-order with respect to the ratio of surface area to solution volume. Direct determinations of both Fe(II) (aq)> and Fe(III) (aq) demonstrated a dramatic loss of Fe(II) from the solution phase in excess of the loss for which oxidation alone could account. Based on rate data, we have concluded that Fe(II) is adsorbed onto the pyrite surface. Furthermore, Fe(II) is preferred as an adsorbate to Fe(III), which we attribute to both electrostatic and acid-base selectivity. We also found that the rate of pyrite oxidation by either Fe(III) (aq) or DO is reduced in the presence of aqueous Fe(II), which leads us to conclude that, under most natural conditions, neither Fe(III) (aq) nor DO directly attacks the pyrite surface. The present evidence suggests a mechanism for pyrite oxidation that involves adsorbed Fe( II ) giving up electrons to DO and the resulting Fe(III) rapidly accepting electrons from the pyrite. The adsorbed Fe is, thus, cyclically oxidized and reduced, while it acts as a conduit for electrons traveling from pyrite to DO. Oxygen is transferred from the hydration sphere of the adsorbed Fe to pyrite S. The cycle of adsorbed Fe oxidation and reduction and the successive addition of oxygen to pyrite S continues until a stable sulfoxy species dissociates from the surface. Prior

  2. MECHANISMS OF NITROUS OXIDE FORMATION IN COAL FLAMES

    Science.gov (United States)

    The paper gives results of a study, using both detailed kinetic modeling and plug-flow simulator experiments, to investigate an unknown mechanism by which N2O is formed in coal flames. This mechanism has considerable importance in determining the influence of common and advanced ...

  3. The effects of trace element content on pyrite oxidation rates

    Science.gov (United States)

    Gregory, D. D.; Lyons, T.; Cliff, J. B.; Perea, D. E.; Johnson, A.; Romaniello, S. J.; Large, R. R.

    2017-12-01

    Pyrite acts as both an important source and sink for many different metals and metalloids in the environment, including many that are toxic. Oxidation of pyrite can release these elements while at the same time producing significant amounts of sulfuric acid. Such issues are common in the vicinity of abandoned mines and smelters, but, as pyrite is a common accessory mineral in many different lithologies, significant pyrite oxidation can occur whenever pyritic rocks are exposed to oxygenated water or the atmosphere. Accelerated exposure to oxygen can occur during deforestation, fracking for petroleum, and construction projects. Geochemical models for pyrite oxidation can help us develop strategies to mitigate these deleterious effects. An important component of these models is an accurate pyrite oxidation rate; however, current pyrite oxidation rates have been determined using relatively pure pyrite. Natural pyrite is rarely pure and has a wide range of trace element concentrations that may affect the oxidation rate. Furthermore, the position of trace elements within the mineral lattice can also affect the oxidation rate. For example, elements such as Ni and Co, which substitute into the pyrite lattice, are thought to stabilize the lattice and thus prevent pyrite oxidation. Alternatively, trace elements that are held within inclusions of other minerals could form a galvanic cell with the surrounding pyrite, thus enhancing pyrite oxidation rates. In this study, we present preliminary analyses from three different pyrite oxidation experiments each using natural pyrite with different trace element compositions. These results show that the pyrite with the highest trace element concentration has approximately an order of magnitude higher oxidation rate compared to the lowest trace element sample. To further elucidate the mechanisms, we employed microanalytical techniques to investigate how the trace elements are held within the pyrite. LA-ICPMS was used to determine the

  4. Reactivity of mechanical activated coals for special utilization

    Energy Technology Data Exchange (ETDEWEB)

    Turcaniova, L.; Kadarova, J.; Imrich, P.; Liptaj, T.; Vidlar, J.; Vasek, J.; Foldyna, F.; Sitek, J.; Balaz, P. [Slovak Academy of Science, Kosice (Slovakia). Inst. of Geotechnology

    2004-09-01

    The paper presents the coal activation effect as disintegration in the nano-submicron range and destruction carbon structure. The Slovak brown coal activated in planetary mill is characterised by destruction of organic structure of coal. The biggest activation effect connected with the destruction of C-C bonds of sp{sup 3} carbons has been confirmed by {sup 13}C NMR spectroscopy in the chemical structure of humic acids extracted from the coal sample activated for a period of 60 min. The specific surface of humic acids is much smaller then that of mechanically activated sample from which they were extracted. The black Czech coal was activated by two stage disintegration. In the first stage of mechanochemical activation using Grinding Aqueous Caustic Leaching, GACL method, a fine dispersed semiproduct is formed with the size of particles from 2.5 to 9000 nm. The additional disintegration using water jet increases the effect of disintegration in the submicron area of the coal product. The volume distribution maximum achieves in this stage about 60 wt% of 750 nm grains.

  5. Technological and economic aspects of coal biodesulfurisation.

    Science.gov (United States)

    Klein, J

    1998-01-01

    The sulfur found in coal is either part of the molecular coal structure (organically bound sulfur), is contained in minerals such as pyrite (FeS2), or occurs in minor quantities in the form of sulfate and elemental sulfur. When pyrite crystals are finely distributed within the coal matrix, mechanical cleaning can only remove part of the pyrite. It can, however, be removed by microbial action requiring only mild conditions. The process involves simple equipment, almost no chemicals, but relatively long reaction times, and treatment of iron sulfate containing process water. Different process configurations are possible, depending on the coal particle size. Coal with particle sizes of less than 0.5 mm is preferably desulfurised in slurry reactors, while lump coal (> 0.5 mm) should be treated in heaps. Investment and operating costs are estimated for different process configurations on an industrial scale. Concerning the organically bound sulfur in coal there is up to now no promising biochemical pathway for the degradation and/or desulfurisation of such compounds.

  6. Highly-productive mechanization systems for coal mining in the Polish coal industry

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, W

    1985-01-01

    Effects of mechanization on underground coal mining in Poland from 1960 to 1980 and mining equipment used in Poland is reviewed. In 1983 black coal output increased to 191.1 Mt. There were 765 working faces, 442 of which with powered supports. Six hundred thirty-four shearer loaders were in use. About 82.7% of coal output fell on faces mined by sets of mining equipment (shearer loaders, powered supports and chain conveyors). The average coal output per working face amounted to 889 t/d. About 50% of mine roadways was driven by heading machines (346 heading machines were in use). The average coal output per face mined by a set of mining equipment amounted to 1248 t/d. About 86% of shearer loaders fell on double drum shearer loaders. Types of mining equipment used in underground mining are reviewed: powered supports (Pioma, Fazos, Glinik and the SOW), shearer loaders (drum shearer loaders and double-drum shearer loaders with chain haulage and chainless haulage systems for unidirectional and bi-directional mining), chain conveyors (Samson, Rybnik). Statistical data on working faces with various sets of equipment are given. 3 references.

  7. Pyrite footprinting of RNA

    International Nuclear Information System (INIS)

    Schlatterer, Jörg C.; Wieder, Matthew S.; Jones, Christopher D.; Pollack, Lois; Brenowitz, Michael

    2012-01-01

    Highlights: ► RNA structure is mapped by pyrite mediated · OH footprinting. ► Repetitive experiments can be done in a powdered pyrite filled cartridge. ► High · OH reactivity of nucleotides imply dynamic role in Diels–Alderase catalysis. -- Abstract: In RNA, function follows form. Mapping the surface of RNA molecules with chemical and enzymatic probes has revealed invaluable information about structure and folding. Hydroxyl radicals ( · OH) map the surface of nucleic acids by cutting the backbone where it is accessible to solvent. Recent studies showed that a microfluidic chip containing pyrite (FeS 2 ) can produce sufficient · OH to footprint DNA. The 49-nt Diels–Alder RNA enzyme catalyzes the C–C bond formation between a diene and a dienophile. A crystal structure, molecular dynamics simulation and atomic mutagenesis studies suggest that nucleotides of an asymmetric bulge participate in the dynamic architecture of the ribozyme’s active center. Of note is that residue U42 directly interacts with the product in the crystallized RNA/product complex. Here, we use powdered pyrite held in a commercially available cartridge to footprint the Diels–Alderase ribozyme with single nucleotide resolution. Residues C39 to U42 are more reactive to · OH than predicted by the solvent accessibility calculated from the crystal structure suggesting that this loop is dynamic in solution. The loop’s flexibility may contribute to substrate recruitment and product release. Our implementation of pyrite-mediated · OH footprinting is a readily accessible approach to gleaning information about the architecture of small RNA molecules.

  8. Mechanization of coal storage bins at thermal electric stations

    Energy Technology Data Exchange (ETDEWEB)

    Bushuev, V P; Dyunze, V M; Sidorenko, I A; Dombrovskii, A N; Orlov, S V

    1987-07-01

    Soviet and foreign methods of mechanizing materials handling at storage depots are discussed. Describes a new method of mechanizing coal storage using a bucket wheel reclaimer and mobile conveyor. Sketches and specifications of the PG-1250.32/21 mobile conveyor and the PRK-1250 bucke wheel reclaimer as well as a flow chart and technical and economic indicators of loading operations are given. Savings realized annually from using the combined PRK-1250 bucke wheel reclaimer and the PG-1250.32/21 mobile conveyor were 280 thousand rubles.

  9. Fabrication and characterization of PDLLA/pyrite composite bone ...

    Indian Academy of Sciences (India)

    Keywords. Polylactic acid; Chinese herbal medicine; pyrite; scaffold; bone regeneration; cell culture. ... Pyrite (FeS2, named as Zi-Ran-Tong in Chinese medicine), as a traditional Chinesemedicine, has been used in the Chinese population to treat bone diseases and to promote bone healing. The mechanical properties of ...

  10. Coal

    International Nuclear Information System (INIS)

    Teissie, J.; Bourgogne, D. de; Bautin, F.

    2001-12-01

    Coal world production represents 3.5 billions of tons, plus 900 millions of tons of lignite. 50% of coal is used for power generation, 16% by steel making industry, 5% by cement plants, and 29% for space heating and by other industries like carbo-chemistry. Coal reserves are enormous, about 1000 billions of tons (i.e. 250 years of consumption with the present day rate) but their exploitation will be in competition with less costly and less polluting energy sources. This documents treats of all aspects of coal: origin, composition, calorific value, classification, resources, reserves, production, international trade, sectoral consumption, cost, retail price, safety aspects of coal mining, environmental impacts (solid and gaseous effluents), different technologies of coal-fired power plants and their relative efficiency, alternative solutions for the recovery of coal energy (fuel cells, liquefaction). (J.S.)

  11. Structure and pozzolanic activity of calcined coal gangue during the process of mechanical activation

    Energy Technology Data Exchange (ETDEWEB)

    Wei Guo; Dongxu Li; Jianhua Chen; Nanru Yang [Yancheng Institute of Technology, Yancheng (China). Department of Material Engineering

    2009-04-15

    On the basis of analyzing coal gangue's chemical and mineral compositions, the structure change of coal gangue during the mechanical activation was investigated by XRD, FTIR, NMR, and the mechanical strength of the cement doped coal gangue with various specific surface area was tested. The experimental results indicate that the lattice structure of metakaolin in coal gangue samples calcined at 700{sup o}C disorganizes gradually and becomes disordered, and the lattice structure of {alpha}-quartz is distorted slightly. The pozzolanic activity of the coal gangue increases obviously with its structural disorganization.

  12. Macromolecule simulation and CH4 adsorption mechanism of coal vitrinite

    Science.gov (United States)

    Yu, Song; Yan-ming, Zhu; Wu, Li

    2017-02-01

    The microscopic mechanism of interactions between CH4 and coal macromolecules is of significant practical and theoretical importance in CBM development and methane storage. Under periodic boundary conditions, the optimal energy configuration of coal vitrinite, which has a higher torsion degree and tighter arrangement, can be determined by the calculation of molecular mechanics (MM) and molecular dynamics (MD), and annealing kinetics simulation based on ultimate analysis, 13C NMR, FT IR and HRTEM. Macromolecular stabilization is primarily due to the van der Waals energy and covalent bond energy, mainly consisting of bond torsion energy and bond angle energy. Using the optimal configuration as the adsorbent, GCMC simulation of vitrinite adsorption of CH4 is conducted. A saturated state is reached after absorbing 17 CH4s per coal vitrinite molecule. CH4 is preferentially adsorbed on the edge, and inclined to gathering around the branched chains of the inner vitrinite sites. Finally, the adsorption parameters are calculated through first principle DFT. The adsorbability order is as follows: aromatic structure> heteroatom rings > oxygen functional groups. The adsorption energy order is as follows: Top graphene. However, the energy of the most preferential location is much lower than that of graphite/graphene. CH4 is more easily absorbed on the surface of vitrinite. Adsorbability varies considerably at different adsorption locations and sites on the surface of vitrinite. Crystal parameter of vitrinite is a = b = c = 15.8 Å and majority of its micropores are blow 15.8 Å, indicating that the vitrinite have the optimum adsorption aperture. It can explain its higher observed adsorption capacities for CH4 compared with graphite/graphene.

  13. A review of the fundamental studies of the copper activation mechanisms for selective flotation of the sulfide minerals, sphalerite and pyrite.

    Science.gov (United States)

    Chandra, A P; Gerson, A R

    2009-01-30

    A review of the considerable, but often contradictory, literature examining the specific surface reactions associated with copper adsorption onto the common metal sulfide minerals sphalerite, (Zn,Fe)S, and pyrite (FeS(2)), and the effect of the co-location of the two minerals is presented. Copper "activation", involving the surface adsorption of copper species from solution onto mineral surfaces to activate the surface for hydrophobic collector attachment, is an important step in the flotation and separation of minerals in an ore. Due to the complexity of metal sulfide mineral containing systems this activation process and the emergence of activation products on the mineral surfaces are not fully understood for most sulfide minerals even after decades of research. Factors such as copper concentration, activation time, pH, surface charge, extent of pre-oxidation, water and surface contaminants, pulp potential and galvanic interactions are important factors affecting copper activation of sphalerite and pyrite. A high pH, the correct reagent concentration and activation time and a short time delay between reagent additions is favourable for separation of sphalerite from pyrite. Sufficient oxidation potential is also needed (through O(2) conditioning) to maintain effective galvanic interactions between sphalerite and pyrite. This ensures pyrite is sufficiently depressed while sphalerite floats. Good water quality with low concentrations of contaminant ions, such as Pb(2+)and Fe(2+), is also needed to limit inadvertent activation and flotation of pyrite into zinc concentrates. Selectivity can further be increased and reagent use minimised by opting for inert grinding and by carefully choosing selective pyrite depressants such as sulfoxy or cyanide reagents. Studies that approximate plant conditions are essential for the development of better separation techniques and methodologies. Improved experimental approaches and surface sensitive techniques with high spatial

  14. Study of the mechanical properties of brown coal

    Energy Technology Data Exchange (ETDEWEB)

    Okruszek, Z

    1980-01-01

    The techniques and the results of studies of the mechanical properties of brown coal discovered in a zone adjacent to the location of the Rogowiec power plant (Poland) are described. The studies were conducted by the geotechnical laboratory of the Polytechnical Institute in the city of Lodz. Included in the program of studies were: tests of the brown coal (eight samples with a diameter to height ratio of d/h = 10.0/7.5; 11.1/7.8; 9.3/8.8; 8.1/6.8; 8.5/9.4; 8.0/8.8; 7.9/7.6 adn 8.8/8.6; dimensions in centimeters) for single axis compression (destroying stress was found to be 0.778; 0.660; 0.376; 0.804; 0.140; 0.472; 0.408 and 0.278 MPa); tests of samples (five units) for shear strength (the chip force is 0.36; 0.46; 0.39; 0.11 and 0.36 kilonewtons); tests of the samples (two samples, both with a diameter of 3.8 cm and a height of 7.6 cm) for stretching (the destructive force is 50.1 and 54.9 kilonewtons); odometric tests to determine the odometric modulus of compressibility of the brown coal (a total of four samples; three of which were loaded by a force in the range of 0.6-1.2 MPa and one in the range of 0-1.1 MPa; the odometric modulus of compressibility is in the range of 45.1 to 116.7 depending on the loading conditions) and tests for triple axial compression (two samples, both with a diameter of 3.8 cm and a height of 7.6 cm; the destroying pressure was found to be equal to 0.5 and 0.27 MPa).

  15. Greigite: a true intermediate on the polysulfide pathway to pyrite

    Directory of Open Access Journals (Sweden)

    Benning Liane G

    2007-03-01

    Full Text Available Abstract The formation of pyrite (FeS2 from iron monosulfide precursors in anoxic sediments has been suggested to proceed via mackinawite (FeS and greigite (Fe3S4. Despite decades of research, the mechanisms of pyrite formation are not sufficiently understood because solid and dissolved intermediates are oxygen-sensitive and poorly crystalline and therefore notoriously difficult to characterize and quantify. In this study, hydrothermal synchrotron-based energy dispersive X-ray diffraction (ED-XRD methods were used to investigate in situ and in real-time the transformation of mackinawite to greigite and pyrite via the polysulfide pathway. The rate of formation and disappearance of specific Bragg peaks during the reaction and the changes in morphology of the solid phases as observed with high resolution microscopy were used to derive kinetic parameters and to determine the mechanisms of the reaction from mackinawite to greigite and pyrite. The results clearly show that greigite is formed as an intermediate on the pathway from mackinawite to pyrite. The kinetics of the transformation of mackinawite to greigite and pyrite follow a zero-order rate law indicating a solid-state mechanism. The morphology of greigite and pyrite crystals formed under hydrothermal conditions supports this conclusion and furthermore implies growth of greigite and pyrite by oriented aggregation of nanoparticulate mackinawite and greigite, respectively. The activation enthalpies and entropies of the transformation of mackinawite to greigite, and of greigite to pyrite were determined from the temperature dependence of the rate constants according to the Eyring equation. Although the activation enthalpies are uncharacteristic of a solid-state mechanism, the activation entropies indicate a large increase of order in the transition state, commensurate with a solid-state mechanism.

  16. Characterization of Egyptian coal from Sinai using Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Eissa, N.A.; Abdel Meguid, M.M.; Deriu, A.; Albanese, G.

    1983-08-01

    The presence of iron bearing minerals in coal makes the Moessbauer Spectroscopy (MS) extremely useful for characterization of coals from different localities. In this paper the MS has been applied to characterize Egyptian coal from Sinai (Maghara). The chemical analysis of this coal is given. The MS results showed that pyritic sulphur (pyrite and marcasite) is the only bearing mineral in Egyptian coal. A review is given for the iron bearing minerals in coals from different countries measured by MS. (author)

  17. Method of synthesizing pyrite nanocrystals

    Science.gov (United States)

    Wadia, Cyrus; Wu, Yue

    2013-04-23

    A method of synthesizing pyrite nanocrystals is disclosed which in one embodiment includes forming a solution of iron (III) diethyl dithiophosphate and tetra-alkyl-ammonium halide in water. The solution is heated under pressure. Pyrite nanocrystal particles are then recovered from the solution.

  18. Application of Acidithiobacillus Ferrooxidans in coal flotation

    Energy Technology Data Exchange (ETDEWEB)

    Amini, E.; Hosseini, T.R.; Oliazadeh, M.; Kolahdoozan, M. [University of Queensland, Brisbane, Qld. (Australia)

    2009-07-01

    Bioflotation is a potential method for removing pyritic sulphur from coal. Sodium cyanide is a well-known depressant for pyrite in flotation of sulphide minerals; however, for coal this reagent is unacceptable from the environmental point of view. This study investigates an alternate to sodium cyanide, Acidithiobacillus Ferrooxidans, a nonharmful bacterial reagent as a pyrite depressant. The flotation behavior of pyrite and other gangue particles using the sodium cyanide and the Ferrooxidans is compared by applying the general first-order flotation model. The kinetic parameters extracted from the model demonstrated that the modified flotation rate of pyrite was reduced, and the selectivity between coal and gangue was improved using the bacteria. These results indicate that Acidithiobacillus Ferrooxidans has potential in removing pyritic sulfur from coal.

  19. Rock Mechanics Studies During Continuous Miner Bases Coal Pillar Extraction in Indian Coalfields

    Czech Academy of Sciences Publication Activity Database

    Ram, S.; Kumar, D.; Koníček, Petr; Singh, A. K.; Kumar, R.; Singh, A. Kr.; Singh, R.

    2015-01-01

    Roč. 111, April 2014-March 2015 (2015), s. 89-104 ISSN 0254-8003 Institutional support: RVO:68145535 Keywords : mining * mechanized depillaring scenario * rock mechanics Subject RIV: DH - Mining, incl. Coal Mining

  20. Self-scrubbing coal

    International Nuclear Information System (INIS)

    Kindig, J.K.

    1992-01-01

    More than 502 million tons - 65 percent of all coal shipped to utilities in 1990 - were above 1.2 pounds of sulfur dioxide per million Btu. Most of the coal, even though cleaned in conventional coal preparation plants, still does not meet the emission limitation the Clean Air Act Amendments mandate for the year 2000. To cope with this fact, most utilities plan to switch to low sulfur (western U.S. or Central Appalachian) coal or install scrubbers. Both solutions have serous drawbacks. Switching puts local miners out of work and weakens the economy in the utility's service territory. Scrubbing requires a major capital expenditure by the utility. Scrubbers also increase the operating complexity and costs of the generating station and produce yet another environmental problem, scrubber sludge. Employing three new cost-effective technologies developed by Customer Coals International (CCl), most non-compliance coals east of the Mississippi River can be brought into year-2000 compliance. The compliance approach employed, depends upon the characteristics of the raw coal. Three types of raw coal are differentiated, based upon the amount of organic sulfur in the coals and the ease (or difficultly) of liberating the pyrite. They are: Low organic sulfur content and pyrite that liberates easily. Moderate organic sulfur content and pyrite that liberates easily. High organic sulfur content or the pyrite liberates with difficulty. In this paper examples of each type of raw coal are presented below, and the compliance approach employed for each is described. The names of the beneficiated coal products produced from each type of raw coal give above are: Carefree Coal, Self-Scrubbing Coal and Dry-Scrubbing Coal

  1. Selected problems of coal mining mechanization in the coal industry of Poland

    Energy Technology Data Exchange (ETDEWEB)

    Antoniak, J; Sikora, W [Politechnika Slaska, Gliwice (Poland)

    1987-01-01

    Discusses conditions for underground coal mining in Poland, types of equipment for coal cutting, mine haulage and strata control and development trends of mining technologies. In 1985, black coal output was 191.6 Mt; 85.3% came from longwall faces mined by sets of mining equipment (coal cutters, chain conveyors and powered supports). The average coal output per longwall face was 881 t/d, output per face mined by sets for mining equipment was 1,134 t/d. In 1985, 653 shearer loaders and 77 coal plows were used in Polish coal mines. Number of shearer loaders is increasing. Shearer loaders with chainless haulage system were safest and most economic. The shearer loaders were equipped with the POLTRAK chainless haulage system developed in Poland. Research programs concentrate on development of new mining equipment for thin seam mining, steep seam mining, longwall mining with hydraulic stowing, efficient strata control by powered or shield supports under conditions of increased stresses or rock burst hazards. 4 refs.

  2. Mechanisms of coal solubilization by the deuteromycetes Trichoderma atroviride and Fusarium oxysporum

    Energy Technology Data Exchange (ETDEWEB)

    Hoelker, U.; Ludwig, S.; Scheel, T.; Hoefer, M. [Bonn Univ. (Germany). Botanisches Inst. und Botanischer Garten

    1999-07-01

    Three different mechanisms can be envisaged that are used by fungi to solubilize coal: the production of alkaline substances, the extrusion of chelators and, of special interest in the scope of biotechnology, the action of enzymes. Whether these mechanisms are operating separately or in various combinations has not yet been finally assessed. The two deuteromycetes Fusarium oxysporum and Trichoderma atroviride solubilize coal by synergistic effects of various different mechanisms depending on the cell metabolism. F. oxysporum seems to solubilize coal by increasing the pH of the mycelial surroundings and by the action of chelators induced during growth in glutamate-containing media (without involvement of enzymes). T. atroviride, on the other hand, appears to use, in addition to an alkaline pH and a high chelator activity, at least two classes of enzyme activity to attack coal: hydrolytic activity for coal solubilization and ligninolytic activity for degradation of humic acids. (orig.)

  3. Geological and Rock Mechanics Perspectives for Underground Coal Gasification in India

    Science.gov (United States)

    Singh, Ajay K.; Singh, Rajendra

    2017-07-01

    The geological resources of coal in India are more than 308 billion tonnes upto a depth of 1200 m, out of which proved reserve has been reported at around 130 billion tonnes. There is an increasing requirement to increase the energy extraction efficiency from coal as the developmental prospects of India increase. Underground coal gasification (UCG) is a potential mechanism which may be utilized for extraction of deep-seated coal reserves. Some previous studies suggest that lignites from Gujarat and Rajasthan, along with tertiary coals from northeastern India can be useful from the point of view of UCG. We discuss some geological literature available for these areas. Coming to the rock mechanics perspectives, during UCG the rock temperature is considerable high. At this temperature, most empirical models of rock mechanics may not be applied. In this situation, the challenges for numerical modelling of UCG sites increases manifold. We discuss some of the important modelling geomechanical issues related to UCG in India.

  4. The use of mechanically activated micronized coal in thermal power engineering

    Directory of Open Access Journals (Sweden)

    Burdukov Anatoliy P.

    2016-01-01

    Full Text Available Coal is one of the main energy resources and development of new promising technologies on its basis is certainly topical. This article discusses the use of new technology of gas and fuel oil replacement by mechanically activated micronized coal in power engineering: ignition and stabilization of pulverized coal flame combustion, as well as gasification of micronized coal in the flow. The new technology coal combustion with two stages of grinding is suggested. Optimization of the scheme of two-stage combustion is calculated. The first experimental data on the combustion process are obtained. The first demonstration tests on gas and heavy oil replacement by micronized coal during boiler ignition were carried out in the real power boiler with the capacity of 320 tons of steam per hour.

  5. Mechanization of operations in underground workings in coal mines and research project trends. [Poland

    Energy Technology Data Exchange (ETDEWEB)

    Reich, K; Skoczynski, W; Sikora, W

    1985-01-01

    Structure of black coal reserves of Poland, imported and Polish made equipment for underground mining, prospects for mechanization of selected operations in underground mines and research programs of the KOMAG Center for Mechanization of Mining are evaluated. Prospects for longwall mining with caving or stowing in thick coal seams (slice mining), thin (0.8 to 1.2 m), level or inclined coal seams and steep seams are analyzed. The following equipment for mechanization of underground mining is evaluated: integrated face systems, shearer loaders, chain conveyors, belt conveyors, coal plows, equipment for mine drivage, hoists, drive systems for mining equipment. The following research programs of the KOMAG Center are reviewed: modernization of face systems for coal seams with uncomplicated mining conditions, development of equipment for thin seam mining, development of types of mining equipment for coal seams from 1.5 to 3.0 m thick with dip angles to 25 degrees, modernization of equipment for thick seam mining, increasing efficiency of mine drivage (new types of heading machines, materials handling equipment for mine drivage), mechanization of auxiliary operations in underground coal mines, improving quality of mining equipment, development of equipment for coal preparation, increasing occupational safety in underground mining.

  6. Pyrolysis of superfine pulverized coal. Part 3. Mechanisms of nitrogen-containing species formation

    International Nuclear Information System (INIS)

    Liu, Jiaxun; Jiang, Xiumin; Shen, Jun; Zhang, Hai

    2015-01-01

    Highlights: • NH 3 and NO formation mechanisms during superfine pulverized coal pyrolysis are investigated. • Influences of temperature, heating rate, particle size, atmosphere, and acid wash on the NH 3 and NO formation are analyzed. • Transformations of nitrogen-containing structures in coal/char during pyrolysis are recognized through XPS observation. • Relationships among nitrogen-containing gaseous species during pyrolysis are discussed. - Abstract: With more stringent regulations being implemented, elucidating the formation mechanisms of nitrogen-containing species during the initial pyrolysis step becomes important for developing new NO x control strategies. However, there is a lack of agreement on the origins of NO x precursors during coal pyrolysis, in spite of extensive investigations. Hence, it is important to achieve a more precise knowledge of the formation mechanisms of nitrogen-contain species during coal pyrolysis. In this paper, pyrolysis experiments of superfine pulverized coal were performed in a fixed bed at low heating rates. The influences of temperature, coal type, particle size and atmosphere on the NH 3 and NO evolution were discussed. There is a central theme to develop knowledge of the relationship between particle sizes and evolving behaviors of nitrogen-containing species. Furthermore, the catalytic role of inherent minerals in coal was proved to be effective on the partitioning of nitrogen during coal pyrolysis. In addition, the conversion pathways of heteroaromatic nitrogen structures in coal/char during pyrolysis were recognized through the X-ray photoelectron spectroscopy (XPS) analysis. Large quantities of pyridinic and quanternary nitrogen functionalities were formed during the thermal degradation. Finally, the relationships among the nitrogen-containing gaseous species during coal pyrolysis were discussed. In brief, a comprehensive picture of the volatile-nitrogen partitioning during coal pyrolysis is obtained in this

  7. Mechanism of Rock Burst Occurrence in Specially Thick Coal Seam with Rock Parting

    Science.gov (United States)

    Wang, Jian-chao; Jiang, Fu-xing; Meng, Xiang-jun; Wang, Xu-you; Zhu, Si-tao; Feng, Yu

    2016-05-01

    Specially thick coal seam with complex construction, such as rock parting and alternative soft and hard coal, is called specially thick coal seam with rock parting (STCSRP), which easily leads to rock burst during mining. Based on the stress distribution of rock parting zone, this study investigated the mechanism, engineering discriminant conditions, prevention methods, and risk evaluation method of rock burst occurrence in STCSRP through setting up a mechanical model. The main conclusions of this study are as follows. (1) When the mining face moves closer to the rock parting zone, the original non-uniform stress of the rock parting zone and the advancing stress of the mining face are combined to intensify gradually the shearing action of coal near the mining face. When the shearing action reaches a certain degree, rock burst easily occurs near the mining face. (2) Rock burst occurrence in STCSRP is positively associated with mining depth, advancing stress concentration factor of the mining face, thickness of rock parting, bursting liability of coal, thickness ratio of rock parting to coal seam, and difference of elastic modulus between rock parting and coal, whereas negatively associated with shear strength. (3) Technologies of large-diameter drilling, coal seam water injection, and deep hole blasting can reduce advancing stress concentration factor, thickness of rock parting, and difference of elastic modulus between rock parting and coal to lower the risk of rock burst in STCSRP. (4) The research result was applied to evaluate and control the risk of rock burst occurrence in STCSRP.

  8. The mechanical properties and hydration characteristics of cement pastes containing added-calcium coal gangue

    Energy Technology Data Exchange (ETDEWEB)

    Dongxu Li; Xuyan Song [Nanjing University of Technology, Nanjing (China). College of Material Science and Engineering

    2008-04-15

    The mechanical properties of several kinds of coal gangue calcined with limestone were researched so as to find the optimum way of calcinations with limestone. The microstructure and property of hydration process of cement pastes containing added-calcium coal gangue were analyzed by means of scanning electron microscope (SEM) and the method of mercury in trusion poremeasurement. When the proper amounst of gypsum and fluorite were taken as mineralizers in the course of calcinations of added-calcium coal gangue, the activity of coal gangue can be effectively improved. The results of mechanical property and structural characteristics such as hydration, hydration products and microstructure etc. of cement pastes containing added-calcium coal gangue are consistent.

  9. EPR- study of paramagnetic features of brown coal from Kiyakty coal deposit after mechanic activation and electron irradiation

    International Nuclear Information System (INIS)

    Ryabikin, Yu.A.; Zashkvara, O.V.; Popov, S.N.; Kairbekov, Zh.K.; Ershova, Zh.R.; Kupchishin, A.I.; Kovtunets, V.A.

    2003-01-01

    Full text: It is known that prospected coal resources exceed, at least by order of magnitude, petroleum reserves decreasing steeply at last time as a result of world oil consumption rise. In this connection the manufacture of different liquid products from coal, especially brown coal, is issue of the day. Liquid fuel yield depends on physical-chemical characteristics and their changes owing to preliminary chemical, mechanical and radiation treatment. In this paper some results of paramagnetic characteristic study of Kiyakty deposit coal as initial one as after its mechanical treatment and electron irradiation are presented. It is discovered that in Kiyakty coal there are, at least, two fractions differed in EPR line width and concentration of free radical states they contained. First fraction has EPR line width ΔH 1 =4-5 Oe and mean free radical states concentration N 1 = 2.4·10 17 sp/g. For samples of second fraction the EPR line width ΔH 2 = 6.6-7.2 Oe and N 2 = 1.8·10 18 sp/g are typical. Thus, in the second fraction the EPR line width and free radical states concentration are greater than in the first case. Besides free radical states in coal EPR signals were found from trivalent iron ions with g-factor approximated 2 and with g=4.3. It the signals with g=4.3, are practically identical for both fractions, their concentrations are neighbour and line width is ΔH 1 = 250 Oe, then for the lines near g=2.0 situation is markedly different. For the first fraction ΔH 1 = 800 Oe whereas for the second case two signals in this g-factor range are observed. The first signal has line width ΔH 1 = 550 Oe and g=l .97, the second is more wide with ΔH 1 = 1000 Oe and g=2.02. We cannot discover significant dependence of free radical states concentration on mechanic activation time. Obviously, life times of complementary free radical states generated in process of coal activation are very low. As Fe 3+ ions, for both fractions it is observed intensity growth of their

  10. Application of brown coal activated mechanically at disposal of heavy metal from waters

    International Nuclear Information System (INIS)

    Brezovska, M.

    2003-01-01

    Sorptive characteristics of activated brown coal from mine of Novaky and impact of mechanical activation on sorption of heavy metals from water were examined. Experimental results indicate suitable choice and good absorption ability of used material

  11. Economical Optimization of the Mechanized Longwall Faces with Top Coal Caving Mining, In Horizontal Slices

    Science.gov (United States)

    Onica, Ilie; Mihăilescu, Viorel; Andrioni, Felicia

    2016-09-01

    To increase the economic and technical performances of the Jiu Valley hard coal mines, the top coal caving, in horizontal slices, mining methods (Bourbaki methods) were introduced, adapted to the local geo-mining conditions. This mining was successfully experimented by using classical technology, using the individual supports and coal blasting. In the future, it is planned to adopt the mechanized technology, with frame supports and shearers. The mechanized longwall faces with top coal caving mining, in horizontal slices, of coal seam no. 3 could be efficient only if the sizes of the top coal height and the panel length determine a minimum cost of production. Therefore, the goal of this paper is the optimization of these parameters, from a technical and economic point of view, taking into account the general model of the cost function, at the panel level. For that, it was necessary to make a certain sequence of analysis involving: technological unit establishment, purpose function and optimizing model. Thus, there attaining to the mathematical model of the unit cost, after determination of all the individual calculation articles, regarding the preparatory workings, coal face equipments, materials, energy, workforce, etc. Because of the complexity of the obtained technical and economic model, to determine the optimum sizes of the panel length and top coal height, it was necessary to archive a sensitivity analysis of the unit cost function to the main parameters implied into this mathematical model.

  12. Development of mechanization of extraction in underground coal mining (part I)

    Energy Technology Data Exchange (ETDEWEB)

    Strzeminski, J

    1984-01-01

    The history of underground coal mining and history of mechanizing underground operations of cutting, strata control, mine haulage, hoisting and ventilation are discussed. The following development periods are characterized: until 1769 (date of steam engine invention by J. Watt), from 1769 to 1945 (period of partial mechanization of operations in underground coal mining), from 1945 (period of comprehensive mechanization and automation). A general description of mining in the first development period is given. Evaluation of the second development period concentrates on mechanization in underground coal mining. The following equipment types are described: cutting (pneumatic picks and pneumatic drills, coal saws developed by Eickhoff, coal cutters developed after 1870, cutter loaders patented in 1925-1927, coal plows and coal cutter loaders), mine haulage (mine cars, conveyors developed in the United Kingdom, Germany and Russia, Poland), strata control at working faces (timber props, steel friction props, roof bars), strata control in the goaf (room and pillar mining, stowing, minestone utilization for stowing in Upper Silesia, hydraulic stowing in Upper Silesia). 5 references.

  13. Study on electromagnetic radiation and mechanical characteristics of coal during an SHPB test

    Science.gov (United States)

    Chengwu, Li; Qifei, Wang; Pingyang, Lyu

    2016-06-01

    Dynamic loads provided by a Split Hopkinson pressure bar are applied in the impact failure experiment on coal with an impact velocity of 4.174-17.652 m s-1. The mechanical property characteristics of coal and an electromagnetic radiation signal can be detected and measured during the experiment. The variation of coal stress, strain, incident energy, dissipated energy and other mechanical parameters are analyzed by the unidimensional stress wave theory. It suggests that with an increase of the impact velocity, the mechanical parameters and electromagnetic radiation increased significantly and the dissipated energy of the coal sample has a high discrete growing trend during the failure process of coal impact. Combined with the received energy of the electromagnetic radiation signal, the relationship between these mechanical parameters and electromagnetic radiation during the failure process of coal burst could be analyzed by the grey correlation model. The results show that the descending order of the gray correlation degree between the mechanical characteristics and electromagnetic radiation energy are impact velocity, maximum stress, the average stress, incident energy, the average strain, maximum strain, the average strain rate and dissipation energy. Due to the correlation degree, the impact velocity and incident energy are relatively large, and the main factor affecting the electromagnetic radiation energy of coal is the energy magnitude. While the relationship between extreme stress and the radiation energy change trend is closed, the stress state of coal has a greater impact on electromagnetic radiation than the strain and destruction which can deepen the research of the coal-rock dynamic disaster electromagnetic monitoring technique.

  14. Carrier-microencapsulation using Si-catechol complex for suppressing pyrite floatability

    Energy Technology Data Exchange (ETDEWEB)

    Jha, R.K.T.; Satur, J.; Hiroyoshi, N.; Ito, M.; Tsunekawa, M. [Hokkaido University, Hokkaido (Japan). Graduate School of Engineering

    2008-11-15

    Pyrite (FeS{sub 2}) is a common sulfide mineral associated with valuable metal minerals and coal, and it is rejected as a gangue mineral using physical separation techniques such as froth flotation and discharged into tailing pond. In the flotation, pyrite is frequently entrapped in the froth due to its hydrophobic nature. Formation of acid mine drainage due to the air-oxidation of pyrite in the tailing pond is also a serious problem. The authors have proposed carrier-microencapsulation (CME) as a method for suppressing both the floatability and oxidation of pyrite. In this method, pyrite is coated with a thin layer of metal oxide or hydroxide using catechol solution as a carrier combined with metal ions. The layer converts the pyrite surface from hydrophobic to hydrophilic and acts as a protective coating against oxidation. The present study demonstrates the effect of CME using Si-catechol complex to suppress the pyrite floatability: The bubble pick-up experiments showed that attachment of pyrite particles to air bubble is suppressed by the CME treatment at pH 4-10, Si-catechol complex concentration over 0.5 mol m{sup -3} and treatment time within 2 min. The Hallimond tube flotation experiments showed that the pyrite floatability is suppressed by the CME treatment even in the presence of typical flotation collectors such as kerosene and xanthate. SEM-EDX analysis confirmed that Si present on the pyrite surface treated by Si-catechol complex, implying that SiO{sub 2} or SiOH{sub 4} layer formed by the CME treatment convert the pyrite surface hydrophobic to hydrophilic.

  15. Mechanical characteristics of fully mechanized top-coal caving face and surrounding rock stress shell

    Energy Technology Data Exchange (ETDEWEB)

    Xie Guang-xiang [Anhui University of Science and Technology, Huainan (China)

    2005-06-15

    The distribution of surrounding rock stress in fully mechanized top-coal caving (FMTC) face was fully researched by large-scale and non-linear three-dimensional numerical simulation and equivalent laboratory. The results show that, there is the structure that is made of macroscopical stress shell composed of high stress binds in overlying strata of FMTC face. Stress shell, which bears and pass load of overlying strata, is primary supporting body. The stress in skewback of stress shell forms abutment pressure of surrounding rock in vicinity of working face. Bond-beam structure lies in reducing zone under stress shell. It only bear partial burden of strata under stress shell. The uppermost mechanical characteristic of FMTC face is lying in the low stress area under stress shell. It is the essential cause of strata behaviors of FMTC face relaxation. On the basis of analyzing stress shell, the mechanical essence that top coal performs a function of bedding is demonstrated. 4 refs., 7 figs.

  16. Report to the United States Congress clean coal technology export markets and financing mechanisms

    International Nuclear Information System (INIS)

    1994-05-01

    This report responds to a Congressional Conference Report that requests that $625,000 in funding provided will be used by the Department to identify potential markets for clean coal technologies in developing countries and countries with economies in transition from nonmarket economies and to identify existing, or new, financial mechanisms or financial support to be provided by the Federal government that will enhance the ability of US industry to participate in these markets. The Energy Information Administration (EIA) expects world coal consumption to increase by 30 percent between 1990 and 2010, from 5.1 to 6.5 billion short tons. Five regions stand out as major foreign markets for the export of US clean coal technologies: China; The Pacific Rim (other than China); South Asia (primarily India); Transitional Economies (Central Europe and the Newly Independent States); and Other Markets (the Americas and Southern Africa). Nearly two-thirds of the expected worldwide growth in coal utilization will occur in China, one quarter in the United States. EIA forecasts nearly a billion tons per year of additional coal consumption in China between 1990 and 2010, a virtual doubling of that country's coal consumption. A 30-percent increase in coal consumption is projected in other developing countries over that same period. This increase in coal consumption will be accompanied by an increase in demand for technologies for burning coal cost-effectively, efficiently and cleanly. In the Pacific Rim and South Asia, rapid economic growth coupled with substantial indigenous coal supplies combine to create a large potential market for CCTS. In Central Europe and the Newly Independent States, the challenge will be to correct the damage of decades of environmental neglect without adding to already-considerable economic disruption. Though the situation varies, all these countries share the basic need to use indigenous low-quality coal cleanly and efficiently

  17. Drainage from coal mines: Chemistry and environmental problems

    International Nuclear Information System (INIS)

    Wildeman, T.

    1991-01-01

    Much of the research on coal-mine drainage chemistry was conducted a decade ago, and now increased environmental awareness has brought about renewed interest in the findings. Consideration of the trace minerals and elements in coal points to the possible generation of acidic waters upon weathering, especially when pyrite is present. When pyrite weathers, it produces H + and Fe 3+ which catalyze the incongruent weathering of other carbonates and sulfides. In this weathering mechanism, catalysis by bacteria is important. Of the environmental problems in coal mine drainage, the mineral acidity of the water is the most serious. This is caused not only by the H + , but also by Mn 4+ , Fe 3+ , and Al 3+ that are found or generated within the drainage. Case studies in Kentucky, Pennsylvania, Illinois, and Colorado show that the abundance and form of pyrite in the deposit and in the overburden determines the level of acidity and the concentration of heavy metal pollutants in the drainage. Recent trends in environmental enforcement that emphasize integrated stream water standards and biotoxicity assays point to the possibility that the concentrations of heavy metals in coal mine drainages may cause environmental concern

  18. Tellurium Enrichment in Jurassic Coal, Brora, Scotland

    Directory of Open Access Journals (Sweden)

    Liam Bullock

    2017-11-01

    Full Text Available Mid-Jurassic pyritic coals exposed at the village of Brora, northern Scotland, UK, contain a marked enrichment of tellurium (Te relative to crustal mean, average world coal compositions and British Isles Carboniferous coals. The Te content of Brora coal pyrite is more than one order of magnitude higher than in sampled pyrite of Carboniferous coals. The Te enrichment coincides with selenium (Se and mercury (Hg enrichment in the rims of pyrite, and Se/Te is much lower than in pyrites of Carboniferous coals. Initial pyrite formation is attributed to early burial (syn-diagenesis, with incorporation of Te, Se, Hg and lead (Pb during later pyrite formation. The source of Te may have been a local hydrothermal system which was responsible for alluvial gold (Au in the region, with some Au in Brora headwaters occurring as tellurides. Anomalous Te is not ubiquitous in coal, but may occur locally, and is detectable by laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS.

  19. Investigation of air gasification of micronized coal, mechanically activated using the plasma control of the process

    Directory of Open Access Journals (Sweden)

    Butakov Evgenii

    2017-01-01

    Full Text Available Combination of the processes of coal combustion and gasification into a single technology of mechano-chemical and plasma-chemical activation is of a considerable scientific and technological interest. Enhancement of coal reactivity at their grinding with mechanical activation is associated with an increase in the reaction rate of carbon material, and at plasma-chemical effect, the main is an increase in reactivity of the oxidizing agent caused by the high plasma temperatures of atomic oxygen. The process of gasification was studied on the 1-MW setup with tangential scroll supply of pulverized coal-air mixture and cylindrical reaction chamber. Coal ground by the standard boiler mill is fed to the disintegrator, then, it is sent to the scroll inlet of the burner-reactor with the transport air. Pulverized coal is ignited by the plasmatron of 10-kW power. In experiments on air gasification of micronized coal, carried out at the temperature in the reaction chamber of 1000-1200°C and air excess α = 0.3-1, the data on CO concentration of 11% and H2 concentration of up to 6% were obtained. Air and air-steam gasification of mechanically-activated micronized coals with plasma control was calculated using SigmaFlow software package.

  20. Investigation of air gasification of micronized coal, mechanically activated using the plasma control of the process

    Science.gov (United States)

    Butakov, Evgenii; Burdukov, Anatoly; Chernetskiy, Mikhail; Kuznetsov, Victor

    2017-10-01

    Combination of the processes of coal combustion and gasification into a single technology of mechano-chemical and plasma-chemical activation is of a considerable scientific and technological interest. Enhancement of coal reactivity at their grinding with mechanical activation is associated with an increase in the reaction rate of carbon material, and at plasma-chemical effect, the main is an increase in reactivity of the oxidizing agent caused by the high plasma temperatures of atomic oxygen. The process of gasification was studied on the 1-MW setup with tangential scroll supply of pulverized coal-air mixture and cylindrical reaction chamber. Coal ground by the standard boiler mill is fed to the disintegrator, then, it is sent to the scroll inlet of the burner-reactor with the transport air. Pulverized coal is ignited by the plasmatron of 10-kW power. In experiments on air gasification of micronized coal, carried out at the temperature in the reaction chamber of 1000-1200°C and air excess α = 0.3-1, the data on CO concentration of 11% and H2 concentration of up to 6% were obtained. Air and air-steam gasification of mechanically-activated micronized coals with plasma control was calculated using SigmaFlow software package.

  1. Device for mechanized loading of coal into the sump of a skip shaft

    Energy Technology Data Exchange (ETDEWEB)

    Orlik, M A

    1982-01-01

    In order to mechanize the process of loading coal and cleaning the sump, the efficiency experts of the mine ''Promyshlennaya'' of the production association ''Vorkutaugol'' have designed a special mechanical loading device which consists of pipes-sleeves, working mechanism-worm and electric drive. The worm lifter is suspended on the beam with clamps and an intermediate floor. Because of the use of mechanical loader, manual operations have been reduced to the minimum (the coal is thrown towards the loading hole manually). Economic effect is R 3100 per year.

  2. Chemical Interactions of Hydraulic Fracturing Biocides with Natural Pyrite

    Science.gov (United States)

    Consolazio, Nizette A.

    significantly. DBNPA is proposed to undergo redox reactions with the pyrite surface, accepting two-electrons from pyrite, and thus becoming reduced. The primary product is the monobrominated analogue of DBNPA, 2-monobromo-3-nitrilopropionamide (or MBNPA). The surface area-normalized first-order initial degradation rate constant was found to be 5.1 L.m-2day-1. It was also determined that the dissolution and oxidation products of pyrite, Fe II, S2O32- and SO4 2- are unlikely to contribute to the reduction of the biocide. Taken together, the results illustrate that a surface reaction with pyrite has the ability to reduce the persistence of DBNPA, and as a consequence change the distribution of its reaction products. The second objective was to quantify the influence of water chemistry and interactions with pyrite on the degradation of the sulfur-containing biocide. Dazomet readily hydrolyzes in water due to the nucleophilic attack of hydroxide (OH-) anions. Thus the half-life of dazomet during the shut-in phase of hydraulic fracturing will decrease with increasing pH: 8.5 hours at pH 4.1 to 3.4 hours at pH 8.2.Dazomet degradation was rapidly accelerated upon exposure to the oxidized pyrite surface, reacting five times faster than hydrolysis in the absence of pyrite at a similar pH. The products measured were identical to those identified on hydrolysis (methyl isothiocyanate and formaldehyde) and no dissolved iron was detected in solutions. This suggests that the dithiocarbamate group in dazomet was able to chemisorb onto the oxidized pyrite surface, shifting the electron density of the molecule which resulted in accelerated hydrolysis of the biocide. The third objective explored the reactivity of various biocide functional groups due to the addition of pyrite. Several elimination mechanisms were identified, and tied to the reactivity of the specific functional group involved. The addition of pyrite led to accelerated degradation of dibromodicyanobutane. This is because the bromine

  3. Retention and reduction of uranium on pyrite surface

    International Nuclear Information System (INIS)

    Eglizaud, N.

    2006-12-01

    In the hypothesis of a storage of the spent fuel in a deep geological formation, understanding the uranium dispersion in the environment is important. Pyrite is a reducing mineral present in the Callovo-Oxfordian argilites, the geological formation actually studied for such a storage. However, pyrite impact on uranium migration has already been poorly studied. The aim of the study was to understand the mechanisms of uranium(VI) retention and reduction on the pyrite surface (FeS 2 ). Solution chemistry was therefore coupled with solid spectroscopic studies (XPS and Raman spectroscopy). All uranium-pyrite interactions experiments were performed under an anoxic atmosphere, in a glove box. Pyrite dissolution under anoxic conditions releases sulfoxy-anions and iron(II), which can then be adsorbed on the pyrite surface. This adsorption was confirmed by interaction experiments using iron(II) isotopic dilution. Uranium(VI) is retained by an exchange reaction with iron(II) adsorbed on sulphur sites, with a maximal amount of sorbed uranium at pH ≥ 5.5. Cobalt(II) and europium(III) are also adsorbed on the pyrite surface above pH 5.5 confirming then that reduction is not required for species to adsorb on pyrite. When the concentration of uranium retained is lower than 4 x 10 -9 mol g -1 , an oxidation-reduction reaction leads to the formation of a uranium (VI) (IV) mixed oxide and to solid sulphur (d.o. ≥ -I). During this reaction, iron remains mostly at the +II oxidation degree. The reaction products seem to passivate the pyrite surface: at higher amounts of retained uranium, the oxidation-reduction reaction is no longer observed. The surface is saturated by the retention of (3.4 ± 0.8) x 10 -7 mol L -1 of uranium(VI). Modelling of uranium sorption at high surface coverage (≥ 4 x 10 -9 mol g -1 ) by the Langmuir model yields an adsorption constant of 8 x 10 7 L mol -1 . Finally, a great excess of uranium(VI) above the saturation concentration allows the observation of

  4. An analytical model of the mechanical properties of bulk coal under confined stress

    Science.gov (United States)

    Wang, G.X.; Wang, Z.T.; Rudolph, V.; Massarotto, P.; Finley, R.J.

    2007-01-01

    This paper presents the development of an analytical model which can be used to relate the structural parameters of coal to its mechanical properties such as elastic modulus and Poisson's ratio under a confined stress condition. This model is developed primarily to support process modeling of coalbed methane (CBM) or CO2-enhanced CBM (ECBM) recovery from coal seam. It applied an innovative approach by which stresses acting on and strains occurring in coal are successively combined in rectangular coordinates, leading to the aggregated mechanical constants. These mechanical properties represent important information for improving CBM/ECBM simulations and incorporating within these considerations of directional permeability. The model, consisting of constitutive equations which implement a mechanically consistent stress-strains correlation, can be used as a generalized tool to study the mechanical and fluid behaviors of coal composites. An example using the model to predict the stress-strain correlation of coal under triaxial confined stress by accounting for the elastic and brittle (non-elastic) deformations is discussed. The result shows a good agreement between the prediction and the experimental measurement. ?? 2007 Elsevier Ltd. All rights reserved.

  5. Effect of mechanical and chemical clay removals by hydrocyclone and dispersants on coal flotation

    Energy Technology Data Exchange (ETDEWEB)

    Oats, W.J.; Ozdemir, O.; Nguyen, A.V. [University of Queensland, Brisbane, Qld. (Australia). School of Chemical Engineering

    2010-04-15

    Fine minerals, mostly clays, are known to have a detrimental effect on coal flotation. This paper focuses on the effect of mechanical and chemical removals of fine minerals by hydrocyclone and dispersants on coal flotation. The experimental results showed that the flotation recovery slightly increased from medium acidic to medium alkaline ranges. The flotation experiments carried out with dispersants at different dosages showed that the dispersants did not enhance the flotation recovery significantly. However, the removal of the fine fraction from the feed using a hydrocyclone significantly increased the flotation recovery. The bubble-particle attachment tests also indicated that the attachment time between an air bubble and the coal particles increased in the presence of clay particles. These attachment time results clearly showed that the clay particles adversely affected the flotation of coal particles by covering the coal surfaces which reduced the efficiency of bubble-coal attachment. An analysis based on the colloid stability theory showed that the clay coating was governed by the van der Waals attraction and that the double-layer interaction played a secondary role. It was also concluded that the best way to increase the flotation recovery in the presence of clays was to remove these fine minerals by mechanical means such as hydrocylones.

  6. Biochemical Removal of HAP Precursors from Coal

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Gregory J

    1997-05-12

    Column biooxidation tests with Kentucky coal confirmed results of earlier shake flask tests showing significant removal from the coal of arsenic, selenium, cobalt, manganese, nickel and cadmium. Rates of pyrite biooxidation in Kentucky coal were only slightly more than half the rates found previously for Indiana and Pittsburgh coals. Removal of pyrite from Pittsburgh coal by ferric ion oxidation slows markedly as ferrous ions accumulate in solution, requiring maintenance of high redox potentials in processes designed for removal of pyrite and hazardous air pollutant (HAP) precursors by circulation of ferric solutions through coal. The pyrite oxidation rates obtained in these tests were used by Unifield Engineering to support the conceptual designs for alternative pyrite and HAP precursor bioleaching processes for the phase 2 pilot plant. Thermophilic microorganisms were tested to determine if mercury could be mobilized from coal under elevated growth temperatures. There was no evidence for mercury removal from coal under these conditions. However, the activity of the organisms may have liberated mercury physically. It is also possible that the organisms dissolved mercury and it readsorbed to the clay preferentially. Both of these possibilities are undergoing further testing. The Idaho National Engineering and Environmental Laboratory's (INEEL) slurry column reactor was operated and several batches of feed coal, product coal, waste solids and leach solutions were submitted to LBL for HAP precursor analysis. Results to date indicate significant removal of mercury, arsenic and other HAP precursors in the combined physical-biological process.

  7. Gas Permeability Evolution Mechanism and Comprehensive Gas Drainage Technology for Thin Coal Seam Mining

    Directory of Open Access Journals (Sweden)

    Fangtian Wang

    2017-09-01

    Full Text Available A thin coal seam mined as a protective coal seam above a gas outburst coal seam plays a central role in decreasing the degree of stress placed on a protected seam, thus increasing gas permeability levels and desorption capacities to dramatically eliminate gas outburst risk for the protected seam. However, when multiple layers of coal seams are present, stress-relieved gas from adjacent coal seams can cause a gas explosion. Thus, the post-drainage of gas from fractured and de-stressed strata should be applied. Comprehensive studies of gas permeability evolution mechanisms and gas seepage rules of protected seams close to protective seams that occur during protective seam mining must be carried out. Based on the case of the LongWall (LW 23209 working face in the Hancheng coal mine, Shaanxi Province, this paper presents a seepage model developed through the FLAC3D software program (version 5.0, Itasca Consulting Group, Inc., Minneapolis, MI, USA from which gas flow characteristics can be reflected by changes in rock mass permeability. A method involving theoretical analysis and numerical simulation was used to analyze stress relief and gas permeability evolution mechanisms present during broken rock mass compaction in a goaf. This process occurs over a reasonable amount of extraction time and in appropriate locations for comprehensive gas extraction technologies. In using this comprehensive gas drainage technological tool, the safe and efficient co-extraction of thin coal seams and gas resources can be realized, thus creating a favorable environment for the safe mining of coal and gas outburst seams.

  8. Kinetic comparison of biological and conventional flotation of coal

    Energy Technology Data Exchange (ETDEWEB)

    Amini, E.; Oliazadeh, M.; Kolahdoozan, M. [University of Queensland, Brisbane, Qld. (Australia)

    2009-03-15

    Froth flotation is commonly used in coal processing to selectively recover the organic material (coal) from inorganic waste material. Tabas coal, located in east Iran, contains fine disseminated pyrite which is floated with coal during flotation, and hence decreasing the quality of the final concentrate. Reagents, such as sodium cyanide, are typically added to depress pyrite. Due to the toxicity of cyanide, alternative strategies for depressing pyrite flotation are being investigated. In this paper the metallurgical performance of Tabas coal treated with sodium cyanide is compared to that of Tabas coal which has undergone bacterial treatment using Acidithiobacillus ferrooxidans. Results indicate that bacterial treatment decreases the flotation rate of pyrite and improves the selectivity between coal and gangue. The possibility of using bacteria in place of toxic chemicals such as cyanide has significant environmental benefit.

  9. Pyrite oxidation under simulated acid rain weathering conditions.

    Science.gov (United States)

    Zheng, Kai; Li, Heping; Wang, Luying; Wen, Xiaoying; Liu, Qingyou

    2017-09-01

    We investigated the electrochemical corrosion behavior of pyrite in simulated acid rain with different acidities and at different temperatures. The cyclic voltammetry, polarization curve, and electrochemical impedance spectroscopy results showed that pyrite has the same electrochemical interaction mechanism under different simulated acid rain conditions, regardless of acidity or environmental temperature. Either stronger acid rain acidity or higher environmental temperature can accelerate pyrite corrosion. Compared with acid rain having a pH of 5.6 at 25 °C, the prompt efficiency of pyrite weathering reached 104.29% as the acid rain pH decreased to 3.6, and it reached 125.31% as environmental temperature increased to 45 °C. Increasing acidity dramatically decreases the charge transfer resistance, and increasing temperature dramatically decreases the passivation film resistance, when other conditions are held constant. Acid rain always causes lower acidity mine drainage, and stronger acidity or high environmental temperatures cause serious acid drainage. The natural parameters of latitude, elevation, and season have considerable influence on pyrite weathering, because temperature is an important influencing factor. These experimental results are of direct significance for the assessment and management of sulfide mineral acid drainage in regions receiving acid rain.

  10. Reconstruction of 3D Micro Pore Structure of Coal and Simulation of Its Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Guang-zhe Deng

    2017-01-01

    Full Text Available This article takes the low permeability coal seam in the coalfield of South Judger Basin in Xinjiang, as a research object. The pore structure characteristics of coal rock mass in low permeability coal seam were analyzed quantitatively using scanning electron microscopy (SEM through the methods of statistics and digital image analysis. Based on the pore structure parameters and the distribution function of the coal rock mass, a three-dimensional porous cylinder model with different porosity was reconstructed by FLAC3D. The numerical simulation study of reconstructed pore model shows that (1 the porosity and the compressive strength have obvious nonlinear relation and satisfy the negative exponential relation; (2 the porosity significantly affects the stress distribution; with the increase of micro porosity, the stress distribution becomes nonuniform; (3 the compressive failures of different models are mainly shear failures, and the shape of fracture section is related to porosity; (4 the variation of seepage coefficient of the pore reconstruction model is consistent with the development of micro cracks. The micro mechanism of the deformation and failure of coal and the interaction of multiphase flow with porosity are revealed, which provides a theoretical reference for the clean development of the low permeability coal seam.

  11. Establishment of the carbon label mechanism of coal chemical products based oncarbon footprint

    Directory of Open Access Journals (Sweden)

    Wu Bishan

    Full Text Available ABSTRACT After redefining the carbon footprint and carbon label, the paper analyzesthe significance of the carbon labels under the background of the low carbon economy development, and establishes the concept of model of the carbon labels mechanism to chemical products. At the same time, the paper quantitatively studies carbon label data sourceof three kinds of coal chemical industry power products, which are fromhaving not CCS technologies of supercritical boiler of coal, using CCS technologies of supercritical boiler of coal and adopting CCS and IGCC technologies to power generation in CCI. Based on the three kinds of differences, the paper puts forward of establishing the carbon labels mechanism of chemical products under the low carbon consumption.

  12. Control effect of fracture on hard coal cracking in a fully mechanized longwall top coal caving face

    Energy Technology Data Exchange (ETDEWEB)

    Jin-ping Wei; Zhong-hua Li; Pei-miao Sang; Shang-qiang Chen [Henan Polytechnic University, Jiaozuo (China). School of Energy Science and Engineering

    2009-03-15

    Through theoretical analysis, simulation test and practice, the law of a fracture's influence on hard top coal press cracking was studied. The study focused on the relation between fracture and coal strength, top coal caving ability and work face layout. Based on the investigation of the fracture system, the control of press cracking was achieved by matching working face to fracture orientation to improve top-coal caving ability and recovery. The matching principle was pointed out: the top-coal caving working face should be perpendicular to or obliquely cross the primary fracture at a large angle, and cross the secondary fracture at a small angle. The rational match can increase the recovery ratio of top-coal and avoid rib spalling. The application of control technology on hard top coal press cracking was introduced at the longwall top-coal caving face. 10 refs., 2 figs., 1 tab.

  13. Biodesulfurization techniques: Application of selected microorganisms for organic sulfur removal from coals. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Elmore, B.B.

    1993-08-01

    As an alternative to post-combustion desulfurization of coal and pre-combustion desulfurization using physicochemical techniques, the microbial desulfurization of coal may be accomplished through the use of microbial cultures that, in an application of various microbial species, may remove both the pyritic and organic fractions of sulfur found in coal. Organisms have been isolated that readily depyritize coal but often at prohibitively low rates of desulfurization. Microbes have also been isolated that may potentially remove the organic-sulfur fraction present in coal (showing promise when acting on organic sulfur model compounds such as dibenzothiophene). The isolation and study of microorganisms demonstrating a potential for removing organic sulfur from coal has been undertaken in this project. Additionally, the organisms and mechanisms by which coal is microbially depyritized has been investigated. Three cultures were isolated that grew on dibenzothiophene (DBT), a model organic-sulfur compound, as the sole sulfur source. These cultures (UMX3, UMX9, and IGTS8) also grew on coal samples as the sole sulfur source. Numerous techniques for pretreating and ``cotreating`` coal for depyritization were also evaluated for the ability to improve the rate or extent of microbial depyritization. These include prewashing the coal with various solvents and adding surfactants to the culture broth. Using a bituminous coal containing 0.61% (w/w) pyrite washed with organic solvents at low slurry concentrations (2% w/v), the extent of depyritization was increased approximately 25% in two weeks as compared to controls. At slurry concentrations of 20% w/v, a tetrachloroethylene treatment of the coal followed by depyritization with Thiobacillus ferrooxidans increased both the rate and extent of depyritization by approximately 10%.

  14. The mechanism of coking pressure generation I: Effect of high volatile matter coking coal, semi-anthracite and coke breeze on coking pressure and plastic coal layer permeability

    Energy Technology Data Exchange (ETDEWEB)

    Seiji Nomura; Merrick Mahoney; Koichi Fukuda; Kenji Kato; Anthony Le Bas; Sid McGuire [Nippon Steel Corporation, Chiba (Japan). Environment and Process Technology Center

    2010-07-15

    One of the most important aspects of the cokemaking process is to control and restrain the coking pressure since excessive coking pressure tends to lead to operational problems and oven wall damage. Therefore, in order to understand the mechanism of coking pressure generation, the permeability of the plastic coal layer and the coking pressure for the same single coal and the same blended coal were measured and the relationship between them was investigated. Then the 'inert' (pressure modifier) effect of organic additives such as high volatile matter coking coal, semi-anthracite and coke breeze was studied. The coking pressure peak for box charging with more uniform bulk density distribution was higher than that for top charging. It was found that the coking pressure peaks measured at different institutions (NSC and BHPBilliton) by box charging are nearly the same. The addition of high volatile matter coking coal, semi-anthracite and coke breeze to a low volatile matter, high coking pressure coal greatly increased the plastic layer permeability in laboratory experiments and correspondingly decreased the coking pressure. It was found that, high volatile matter coking coal decreases the coking pressure more than semi-anthracite at the same plastic coal layer permeability, which indicates that the coking pressure depends not only on plastic coal layer permeability but also on other factors. Coking pressure is also affected by the contraction behavior of the coke layer near the oven walls and a large contraction decreases the coal bulk density in the oven center and hence the internal gas pressure in the plastic layer. The effect of contraction on coking pressure needs to be investigated further. 33 refs., 18 figs., 5 tabs.

  15. An integrated program for developing auxillary processes and mechanization of physical labor in coal enterprises

    Energy Technology Data Exchange (ETDEWEB)

    Lostorfer, R.; Bendzsak, I.; Jakucs, S.; Lahorszki, L.; Rosa, A.; Szalai, K.

    1979-01-01

    After explaining the long-term plan of coal enterprises, a review is given of the engineering and economic system of an enterprise. A detailed analysis of the auxilliary processes and mechanization of physical labor is presented. A description of underground and surface transport, repair of mining vehicles, stock-piling and preservation of tailings are presented.

  16. Degradation of Diclofenac by sonosynthesis of pyrite nanoparticles.

    Science.gov (United States)

    Khabbaz, M; Entezari, M H

    2017-02-01

    The aim of this work is to evaluate the ability of synthesized pyrite nanoparticles (NPs) on the degradation of Diclofenac (DCF) as a model pharmaceutical pollutant. Pyrite NPs were synthesized by sonication with 20 kHz apparatus under optimum conditions. The effects of pyrite loading (0.02-0.20 g/L), DCF concentration (10-50 mg/L) and initial pH (2-10) on the degradation were investigated. The results revealed that the NPs have a great activity in the degradation of DCF with 25 mg/L concentration. A first-order kinetic model was found to match the experimental data. Complete degradation (100%) of DCF was achieved by pyrite within 3 min and 20 min in acidic and natural pH, respectively. To gain an understanding of the degradation mechanism and the role of pyrite, a UV-Vis spectrophotometer was employed to follow the DCF concentration. In addition, the Chemical Oxygen Demand (COD) and the amounts of ammonium and chloride ions verified complete degradation of DCF in both pH values. The results demonstrated that Fe 2+ ions were generated by the pyrite surface and the hydroxyl radical (OH) was formed by Fe 2+ ions through the Fenton reaction. Based on using radical scavengers in the degradation process, OH was mainly responsible for the fast degradation of DCF. COD measurements confirmed that DCF finally degraded to further oxidized forms (NH 4 + , Cl - ). Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. A study on measures to reduce production cost of long-running collieries and coal mining mechanization

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-01

    The reducing coal market has been enforcing the coal industry to make exceptional rationalization and restructuring efforts since the end of the eighties. To the competition from crude oil and natural gas has been added the growing pressure from rising wages and rising production cost as the working get deeper. To improve the competitive position of the remaining 11 coal mines after the rationalization of the industry, studies to improve mining system have been carried out. This report consists of 3 subjects. 1) Designing of the bord and pillar mining method to extract gently inclined seams of the Dogye coal mine. 2) Mechanization of coal cutting by plough. 3) Achievement of the mechanization of coal mining compared to the previous year. (author). 27 refs.

  18. Desulphurization of coal: bioleaching versus bioconditioning and flotation

    Energy Technology Data Exchange (ETDEWEB)

    M. Zeki Dogan; Gulhan Ozbayoglu [Istanbul Technical University, Istanbul (Turkey). Faculty of Mining

    2007-07-01

    There are two bio-desulphurization methods for the removal of pyritic sulphur, namely, bacterial leaching and bacterial conditioning for pyrite depression followed by flotation of coal. Bacterial leaching is a slow process, consequently, microbial desulphurization is focused on conditioning coal by bacteria for a short time, followed by flotation. The application of Acidithiobacillus ferrooxidans in bioconditioning followed by flotation process help the oxidation of pyrite surface and enhance its depression during the flotation of coal. By bacterial conditioning for 4 hours followed by flotation, almost 78 % pyritic sulphur removal was attained with the yield of 78 % in the floated coal, whereas bacterial leaching resulted in pyritic sulphur removal of 56.60 % in 10 days. 17 refs., 5 tabs.

  19. Effects of Heating Rate on the Dynamic Tensile Mechanical Properties of Coal Sandstone during Thermal Treatment

    Directory of Open Access Journals (Sweden)

    Ming Li

    2017-01-01

    Full Text Available The effects of coal layered combustion and the heat injection rate on adjacent rock were examined in the process of underground coal gasification and coal-bed methane mining. Dynamic Brazilian disk tests were conducted on coal sandstone at 800°C and slow cooling from different heating rates by means of a Split Hopkinson Pressure Bar (SHPB test system. It was discovered that thermal conditions had significant effects on the physical and mechanical properties of the sandstone including longitudinal wave velocity, density, and dynamic linear tensile strength; as the heating rates increased, the thermal expansion of the sandstone was enhanced and the damage degree increased. Compared with sandstone at ambient temperature, the fracture process of heat-treated sandstone was more complicated. After thermal treatment, the specimen had a large crack in the center and cracks on both sides caused by loading; the original cracks grew and mineral particle cracks, internal pore geometry, and other defects gradually appeared. With increasing heating rates, the microscopic fracture mode transformed from ductile fracture to subbrittle fracture. It was concluded that changes in the macroscopic mechanical properties of the sandstone were result from changes in the composition and microstructure.

  20. A study of the rib fall mechanism in soft coal and its control at a fully-mechanized top-coal caving face

    Energy Technology Data Exchange (ETDEWEB)

    Fang Xin-qiu; He Jie; Li Hai-chao [China University of Mining & Technology, Xuzhou (China). School of Mines

    2009-05-15

    The factors involved in rib-fall at a fully-mechanized top-coal caving face in the Wuyang mine were analyzed. The mechanical stress characteristics and the mechanism of rib-fall were modeled. Control principles and methods were proposed and a control project, and parameters for it, was identified. An underground industrial scale test was subsequently completed. The results show that arc shaped 'sliding surfaces' exist in the rib. The critical height of stable areas is 1.8 meters. The key to rib stability is the control of this arc shaped surface. Wooden bolts are used in the serious rib-fall zone to stabilize the rib. After implementation of the new project rib fall depth and scope were reduced significantly and tip-to-face caving was effectively controlled. 10 refs., 5 figs.

  1. Possibility of applying mechanized coal mining in the mine 'Soko', with the comparative advantages of production results and impact

    Directory of Open Access Journals (Sweden)

    Denić Miodrag

    2014-01-01

    Full Text Available Mining method applied in the RMU 'Soko', is repeatedly technologically modified and reached the maximum limit in terms of productivity, level of job performance and safety at work. And all the other methods, which are in the technological process of obtaining coal rely on the technology of drilling-blasting works, in terms of the mine 'Soko', can not allow mass production of coal, regarding natural and technical-technological conditions prevailing in Sokobanja coal basin. Therefore, this paper proposes a possible solution which would enable a significant increase in annual production by appling mechanized coal mining system.

  2. Investigation of combustion and gasification mechanically activated coal fuel of various degrees of metamorphism on the 5-MW heat setup

    Directory of Open Access Journals (Sweden)

    Butakov Evgenii

    2017-01-01

    Full Text Available The technology of mechanochemical activation of combustion and gasification of coals is of unquestionable scientific and technical interest; an increase in chemical activity of coals at their mechanically activated grinding is associated with an increase in the rate of reaction of the coal substance. To study the combustion and gasification process, the reactor model with tangential scroll input of coal-air suspension and cylindrical reaction chamber was used at the 5-MW thermal power plant. The experiments were carried out with coals of G and SS grades of the Kuznetsk deposit. Coal, ground after the boiler’s standard mill, is fed by a feeder to the disintegrator; then, it enters the scroll inlet of the reactor burner with transport air. The suspension is ignited by a gas igniting device with the power of 50 kW. In experiments on combustion and gasification of fine coal performed at the temperature in the reaction chamber of 1000-1300°C and air excess α = 0.5-0.7, the data on concentrations of CO and H2 were obtained: for coal of grade G, concentration of H2 was 6.3% and concentration of CO was 15.3%; for coal of SS grade, concentration of H2 was 9.5% and concentration of CO was 15.6%.

  3. Empirical approach for designing of support system in mechanized coal pillar mining

    Energy Technology Data Exchange (ETDEWEB)

    Kushwaha, A.; Singh, S.K.; Tewari, S.; Sinha, A. [Central Institute of Mining & Fuel Research, Dhanbad (India)

    2010-10-15

    Mechanized room-and-pillar system of coal pillar mining using side dump loading machine or load haul dumper machine, or by continuous miner, is the presently most dominant under ground method of extraction in India. Under this method of extraction, strata control is a major problem affecting safety and productivity of the mine. As per existing Director General of Mine Safety guidelines, systematic support rules must be followed at the depillaring faces irrespective of immediate roof rock type and competency. Therefore, there is a high chance that sometimes these systematic support rules give unnecessarily high support, or sometimes inadequate support, which may lead to roof failure at the face. As a result, there is a big loss of life and material including coal in terms of left-outribs/stooks and other associated mining equipment deployed at the faces. Therefore, in the present paper, authors attempted to develop generalized empirical equations for estimating the required support load density at different places of the face based on geotechnical parameters of the mine and physico-mechanical properties of the immediate roof rocks for designing of support system during mechanized coal pillar mining.

  4. Micostructural and mechanical properties of geopolymers synthesised from three coal fly ashes from South Africa

    CSIR Research Space (South Africa)

    Dludlu, MK

    2017-01-01

    Full Text Available In this study, coal fly ashes (CFAs) from three different boiler sites in South Africa, Eskom (E coal fly ash), George Mukhari Academic Hospital (GMH coal fly ash), and KarboChem (KBC coal fly ash), were used to produce geopolymers. The coal fly...

  5. Operating a pneumatic-mechanical flotation machine for coal-slurry flotation

    Energy Technology Data Exchange (ETDEWEB)

    Shmaenok, N M; Bedran, N G; Konstantinov, V K; Kochetkov, Yu I; Sysoev, V S

    1976-01-01

    The FPM-GMO-1.6 pneumatic-mechanical flotation machine is easy to operate and regulate and maintains a high throughput at a low energy consumption. The flotation process is stable, the quality of the concentrate and tailings satisfactory, and the selectivity of separation high. The machine cannot handle coal slurries at higher throughputs because the rate of froth removal is too low across the entire flotation front. Experience on the pneumatic-mechanical flotation machine at the ''Kolosnikovskaya'' Central Washery indicates that a similar machine should be developed for a throughput of 1000 m/sup 3//hr.

  6. Selection of an Appropriate Mechanized Mining Technical Process for Thin Coal Seam Mining

    Directory of Open Access Journals (Sweden)

    Chen Wang

    2015-01-01

    Full Text Available Mechanized mining technical process (MMTP related to the control method of the shearer is a vital process in thin coal seam mining operations. An appropriate MMTP is closely related to safety, productivity, labour intensity, and efficiency. Hence, the evaluation of alternative MMTP is an important part of the mining design. Several parameters should be considered in MMTP evaluation, so the evaluation is complex and must be compliant with a set of criteria. In this paper, two multiple criteria decision-making (MCDM methods, Analytic Hierarchy Process (AHP and Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE, were adopted for this evaluation. Then, the most appropriate MMTP for a thin coal seam working face was selected in China.

  7. Copyrolysis of Biomass and Coal: A Review of Effects of Copyrolysis Parameters, Product Properties, and Synergistic Mechanisms

    Science.gov (United States)

    2016-01-01

    Concerns in the last few decades regarding the environmental and socioeconomic impacts of the dependence on fossil fuels have resulted in calls for more renewable and alternative energy sources. This has led to recent interest in copyrolysis of biomass and coal. Numerous reviews have been found related to individual pyrolysis of coal and biomass. This review deals mainly with the copyrolysis of coal and biomass and then compares their results with those obtained using coal and biomass pyrolysis in detail. It is controversial whether there are synergistic or additive behaviours when coal and biomass are blended during copyrolysis. In this review, the effects of reaction parameters such as feedstock types, blending ratio, heating rate, temperature, and reactor types on the occurrence of synergy are discussed. Also, the main properties of the copyrolytic products are pointed out. Some possible synergistic mechanisms are also suggested. Additionally, several outlooks based on studies in the literature are also presented in this paper. PMID:27722171

  8. Study of Acoustic Emission and Mechanical Characteristics of Coal Samples under Different Loading Rates

    Directory of Open Access Journals (Sweden)

    Huamin Li

    2015-01-01

    Full Text Available To study the effect of loading rate on mechanical properties and acoustic emission characteristics of coal samples, collected from Sanjiaohe Colliery, the uniaxial compression tests are carried out under various levels of loading rates, including 0.001 mm/s, 0.002 mm/s, and 0.005 mm/s, respectively, using AE-win E1.86 acoustic emission instrument and RMT-150C rock mechanics test system. The results indicate that the loading rate has a strong impact on peak stress and peak strain of coal samples, but the effect of loading rate on elasticity modulus of coal samples is relatively small. When the loading rate increases from 0.001 mm/s to 0.002 mm/s, the peak stress increases from 22.67 MPa to 24.99 MPa, the incremental percentage is 10.23%, and under the same condition the peak strain increases from 0.006191 to 0.007411 and the incremental percentage is 19.71%. Similarly, when the loading rate increases from 0.002 mm/s to 0.005 mm/s, the peak stress increases from 24.99 MPa to 28.01 MPa, the incremental percentage is 12.08%, the peak strain increases from 0.007411 to 0.008203, and the incremental percentage is 10.69%. The relationship between acoustic emission and loading rate presents a positive correlation, and the negative correlation relation has been determined between acoustic emission cumulative counts and loading rate during the rupture process of coal samples.

  9. Inorganic Constituents in Coal

    Directory of Open Access Journals (Sweden)

    Rađenović A.

    2006-02-01

    Full Text Available Coal contains not only organic matter but also small amounts of inorganic constituents. More thanone hundred different minerals and virtually every element in the periodic table have been foundin coal. Commonly found group minerals in coal are: major (quartz, pyrite, clays and carbonates,minor, and trace minerals. Coal includes a lot of elements of low mass fraction of the orderof w=0.01 or 0.001 %. They are trace elements connected with organic matter or minerals comprisedin coal. The fractions of trace elements usually decrease when the rank of coal increases.Fractions of the inorganic elements are different, depending on the coal bed and basin. A varietyof analytical methods and techniques can be used to determine the mass fractions, mode ofoccurrence, and distribution of organic constituents in coal. There are many different instrumentalmethods for analysis of coal and coal products but atomic absorption spectroscopy – AAS is theone most commonly used. Fraction and mode of occurrence are one of the main factors that haveinfluence on transformation and separation of inorganic constituents during coal conversion.Coal, as an important world energy source and component for non-fuels usage, will be continuouslyand widely used in the future due to its relatively abundant reserves. However, there is aconflict between the requirements for increased use of coal on the one hand and less pollution onthe other. It’s known that the environmental impacts, due to either coal mining or coal usage, canbe: air, water and land pollution. Although, minor components, inorganic constituents can exert asignificant influence on the economic value, utilization, and environmental impact of the coal.

  10. Investigations concerning the mechanism of action of brown-coal coke particles in aerobic biological waste water treatment

    International Nuclear Information System (INIS)

    Rieger, W.

    1990-01-01

    At the start of this work experience with the use of brown coal coke in the activated sludge process was lacking entirely. It therefore was necessary to carry through preliminary experiments in order to practically test the effect of Grown-coal coke. In two technical-scale experiments and a pilot test, very good results were obtained with the application of brown-coal coke to activated sludge. These, and previously published results, permitted to evolve moodel concepts of the mechanism of action of coal, especially brown coal coke, in activated sludge. According to these concepts the coal particles act as buffers and a temporary adsorbent of oxygen and waste water constituents. This in turn stimulates the colonization of the surface with microorganisms. In order to corroborate these model concepts, the - adsorption and desorption of solved oxygen to coal in a watery medium and - the effect of coal over a longer period of time were investigated. The results in essence confirm the model concepts. (UWa) [de

  11. Genesis of some tertiary Indian coals from the chemical composition ...

    Indian Academy of Sciences (India)

    Baruah. 2008) that in northeast Indian coals, the major minerals (wt% >5) identified in the crystalline matter of coal are quartz, kaolin, illite, feldspar, calcite, pyrite, and gypsum. Vassilev et al. (2010a, b) reported that the rank of the coal increases with.

  12. Mechanism of plasma-arc formation of fullerenes from coal and related materials

    Energy Technology Data Exchange (ETDEWEB)

    Pang, L S.K.; Wilson, M A; Quezada, R A [CSIRO Petroleum, North Ryde (Australia); and others

    1996-12-31

    When an arc is struck across graphite or coal electrodes in a helium atmosphere several products are formed including soot containing fullerenes. The mechanism by which fullerenes and nanotubes are formed is not understood. At arc temperatures exceeding 3000{degrees}C, highly ordered fullerenes might be expected to be less stable than graphite, and hence fullerene production is believed to proceed in cooler regions at the edge of the arc. There is irrefutable evidence that [C{sub 60}]-fullerene grows in a plasma from atomic carbon vapour or equivalent. When {sup 13}C-labelled carbon powder is packed into the anode, the fullerenes as produced contain a statistical distribution of {sup 13}C atoms. This implies that graphite has split into small units, predominantly C{sub 1} or C{sub 2} in the plasma and these units are involved in fullerene formation. When coal or other organic materials are used in the anode, weaker bonds are present, which may break preferentially. As a result, larger fragments, other than C{sub 1} and C{sub 2} units can exist in the plasma. This paper demonstrates the existence of such larger fragments when various coals are used and this implies that fullerenes can be formed from larger units than C{sub 1} and C{sub 2}. The distribution of polycyclic hydrocarbons formed depends very much on the structure of the coal used for the arcing experiments. The distribution of the natural abundance of {sup 13}C/{sup 12}C ratios in the fullerene products further supports this evidence.

  13. Attenuation of pyrite oxidation with a fly ash pre-barrier: Reactive transport modelling of column experiments

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Lopez, R.; Cama, J.; Nieto, J.M.; Ayora, C.; Saaltink, M.W. [University of Huelva, Huelva (Spain). Dept. of Geology

    2009-09-15

    Conventional permeable reactive barriers (PRBs) for passive treatment of groundwater contaminated by acid mine drainage (AMD) use limestone as reactive material that neutralizes water acidity. However, the limestone-alkalinity potential ceases as inevitable precipitation of secondary metal-phases on grain surfaces occurs, limiting its efficiency. In the present study, fly ash derived from coal combustion is investigated as an alternative alkalinity generating material for the passive treatment of AMD using solution-saturated column experiments. Unlike conventional systems, the utilization of fly ash in a pre-barrier to intercept the non-polluted recharge water before this water reacts with pyrite-rich wastes is proposed. Chemical variation in the columns was interpreted with the reactive transport code RETRASO. In parallel, kinetics of fly ash dissolution at alkaline pH were studied using flow-through experiments and incorporated into the model. In a saturated column filled solely with pyritic sludge-quartz sand (1: 10), oxidation took place at acidic conditions (pH 3.7). According to SO{sub 4}{sup 2-} release and pH, pyrite dissolution occurred favourably in the solution-saturated porous medium until dissolved O{sub 2} was totally consumed. In a second saturated column, pyrite oxidation took place at alkaline conditions (pH 10.45) as acidity was neutralized by fly ash dissolution in a previous level. At this pH Fe release from pyrite dissolution was immediately depleted as Fe-oxy(hydroxide) phases that precipitated on the pyrite grains, forming Fe-coatings (microencapsulation). With time, pyrite microencapsulation inhibited oxidation in practically 97% of the pyritic sludge. Rapid pyrite-surface passivation decreased its reactivity, preventing AMD production in the relatively short term.

  14. Mode of occurrence of arsenic in four US coals

    Science.gov (United States)

    Kolker, A.; Huggins, Frank E.; Palmer, C.A.; Shah, N.; Crowley, S.S.; Huffman, G.P.; Finkelman, R.B.

    2000-01-01

    An integrated analytical approach has been used to determine the mode of occurrence of arsenic in samples of four widely used US coals: the Pittsburgh, Illinois #6, Elkhorn/Hazard, and Wyodak. Results from selective leaching, X-ray absorption fine structure (XAFS) spectroscopy, and electron microprobe analysis show that pyrite is the principal source of arsenic in the three bituminous coals, but the concentration of As in pyrite varies widely. The Wyodak sample contains very little pyrite; its arsenic appears to be primarily associated with organics, as As3+, or as arsenate. Significant (10-40%) fractions of arsenate, derived from pyrite oxidation, are also present in the three bituminous coal samples. This information is essential in developing predictive models for arsenic behavior during coal combustion and in other environmental settings.

  15. Distribution of trace elements in selected pulverized coals as a function of particle size and density

    Science.gov (United States)

    Senior, C.L.; Zeng, T.; Che, J.; Ames, M.R.; Sarofim, A.F.; Olmez, I.; Huggins, Frank E.; Shah, N.; Huffman, G.P.; Kolker, A.; Mroczkowski, S.; Palmer, C.; Finkelman, R.

    2000-01-01

    Trace elements in coal have diverse modes of occurrence that will greatly influence their behavior in many coal utilization processes. Mode of occurrence is important in determining the partitioning during coal cleaning by conventional processes, the susceptibility to oxidation upon exposure to air, as well as the changes in physical properties upon heating. In this study, three complementary methods were used to determine the concentrations and chemical states of trace elements in pulverized samples of four US coals: Pittsburgh, Illinois No. 6, Elkhorn and Hazard, and Wyodak coals. Neutron Activation Analysis (NAA) was used to measure the absolute concentration of elements in the parent coals and in the size- and density-fractionated samples. Chemical leaching and X-ray absorption fine structure (XAFS) spectroscopy were used to provide information on the form of occurrence of an element in the parent coals. The composition differences between size-segregated coal samples of different density mainly reflect the large density difference between minerals, especially pyrite, and the organic portion of the coal. The heavy density fractions are therefore enriched in pyrite and the elements associated with pyrite, as also shown by the leaching and XAFS methods. Nearly all the As is associated with pyrite in the three bituminous coals studied. The sub-bituminous coal has a very low content of pyrite and arsenic; in this coal arsenic appears to be primarily organically associated. Selenium is mainly associated with pyrite in the bituminous coal samples. In two bituminous coal samples, zinc is mostly in the form of ZnS or associated with pyrite, whereas it appears to be associated with other minerals in the other two coals. Zinc is also the only trace element studied that is significantly more concentrated in the smaller (45 to 63 ??m) coal particles.

  16. Pyrite: A blender plugin for visualizing molecular dynamics simulations using industry-standard rendering techniques.

    Science.gov (United States)

    Rajendiran, Nivedita; Durrant, Jacob D

    2018-05-05

    Molecular dynamics (MD) simulations provide critical insights into many biological mechanisms. Programs such as VMD, Chimera, and PyMOL can produce impressive simulation visualizations, but they lack many advanced rendering algorithms common in the film and video-game industries. In contrast, the modeling program Blender includes such algorithms but cannot import MD-simulation data. MD trajectories often require many gigabytes of memory/disk space, complicating Blender import. We present Pyrite, a Blender plugin that overcomes these limitations. Pyrite allows researchers to visualize MD simulations within Blender, with full access to Blender's cutting-edge rendering techniques. We expect Pyrite-generated images to appeal to students and non-specialists alike. A copy of the plugin is available at http://durrantlab.com/pyrite/, released under the terms of the GNU General Public License Version 3. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  17. Pyrite in the Mesoarchean Witwatersrand Supergroup, South Africa

    OpenAIRE

    2012-01-01

    Ph.D. Petrographic, chemical and multiple sulfur isotope analyses were conducted on pyrite from argillaceous, arenaceous and rudaceous sedimentary rocks from the Mesoarchean Witwatersrand Supergroup. Following detailed petrographic analyses, four paragenetic associations of pyrite were identified. These include: 1) Detrital pyrite (derived from an existing rock via weathering and/or erosion). 2) Syngenetic pyrite (formed at the same time as the surrounding sediment). 3) Diagenetic pyrite (...

  18. Role of non-ferrous coal minerals and by-product metallic wastes in coal liquefaction. Technical progress report, December 1, 1980-February 28, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Garg, D.; Givens, E.N.; Schweighardt, F.K.; Curtis, C.W.; Guin, J.A.; Huang, W.J.; Shridharani, K.

    1981-04-01

    Results from screening studies showed that the pyrite samples separated from various coal seams had similar catalytic activity. The addition of all the pyrite samples to feed slurry increased conversion of coal and production of oil. A sample of fusinite was also tested for its liquefaction behavior with and without added pyrite. The addition of pyrite increased the conversion of fusinite and production of oil. These results show that pyrite catalyzes the conversion of fusinite and therefore improves overall coal conversion. Conversion of coal and oil production increased by impregnating coal with iron and molybdenum compounds. Coal conversion and oil production also increased with increasing concentration of both iron and molybdenum impregnated on coal. Addition of various transition metal sulfides increased coal conversion and oil production. Dramatic improvements were noted with nickel, vanadium, and tin sulfides. Addition of transition metal naphthenates produced mixed results; some of them improved coal conversion and others had no effect. The effect of metal concentration on coal conversion was also not clear. Deep cleaning of coal did not affect coal conversion, but it significantly reduced oil production. Addition of pyrite separated from coal to deep cleaned coal sample regained the oil production to the original value, i.e., oil produced from liquefaction of raw coal.Coal cleaned by oil agglomeration gave highest coal conversion and oil production. Basic and non-basic nitrogen compounds reduced the naphthalene hydrogenation activity of both Co-Mo-Al and sulfided Fe/sub 2/O/sub 3/. Sulfided Fe/sub 2/O/sub 3/ was inactive for denitrogenation of quinoline, and the reaction product mainly consisted of hydrogenated and hydrocracked quinoline. On the contrary, Co-Mo-Al was active for denitrogenation of quinoline, resulting in lower quinoline poisoning.

  19. Cross flow cyclonic flotation column for coal and minerals beneficiation

    Science.gov (United States)

    Lai, Ralph W.; Patton, Robert A.

    2000-01-01

    An apparatus and process for the separation of coal from pyritic impurities using a modified froth flotation system. The froth flotation column incorporates a helical track about the inner wall of the column in a region intermediate between the top and base of the column. A standard impeller located about the central axis of the column is used to generate a centrifugal force thereby increasing the separation efficiency of coal from the pyritic particles and hydrophillic tailings.

  20. Enhanced bioleaching on attachment of indigenous acidophilic bacteria to pyrite surface

    Science.gov (United States)

    Wi, D. W.; Cho, K. H.; Kim, B. J.; Choi, N. C.; Park, C. Y.

    2012-04-01

    In recent years, bioleaching has been widely applied on an industrial scale due to the advantages of low cost and environment friendliness. The direct contact mechanism of bioleaching assumes the action of a metal sulfide-attached cell oxidizing the mineral by an enzyme system with oxygen to sulfate and metal cations. Fundamental surface properties of sulfide particles and leaching-bacteria in bioleaching play the key role in the efficiency of this process. The aim of this work is to investigate of direct contact bioleaching mechanism on pyrite through attachment properties between indigenous acidophilic bacteria and pyrite surfaces. The bacteria were obtained from sulfur hot springs, Hatchobaru thermal electricity plant in Japan. And pyrite was collected from mine waste from Gwang-yang abandoned gold mines, Korea. In XRD analyses of the pyrite, x-ray diffracted d-value belong to pyrite was observed. The indigenous acidophilic bacteria grew well in a solution and over the course of incubation pH decreased and Eh increased. In relation to a bacterial growth-curve, the lag phase was hardly shown while the exponential phase was very fast. Bioleaching experiment result was showed that twenty days after the indigenous acidophilic bacteria were inoculated to a pyrite-leaching medium, the bacterial sample had a greater concentration of Fe and Zn than within the control sample. In SEM-EDS analyses, rod-shaped bacteria and round-shaped microbes were well attached to the surface of pyrite. The size of the rod-shaped bacteria ranged from 1.05~1.10 ? to 4.01~5.38 ?. Round-shaped microbes were more than 3.0 ? in diameter. Paired cells of rod-shaped bacteria were attached to the surface of pyrite linearly.

  1. Retention and reduction of uranium on pyrite surface; Retention et reduction de l'uranium a la surface de la pyrite

    Energy Technology Data Exchange (ETDEWEB)

    Eglizaud, N

    2006-12-15

    In the hypothesis of a storage of the spent fuel in a deep geological formation, understanding the uranium dispersion in the environment is important. Pyrite is a reducing mineral present in the Callovo-Oxfordian argilites, the geological formation actually studied for such a storage. However, pyrite impact on uranium migration has already been poorly studied. The aim of the study was to understand the mechanisms of uranium(VI) retention and reduction on the pyrite surface (FeS{sub 2}). Solution chemistry was therefore coupled with solid spectroscopic studies (XPS and Raman spectroscopy). All uranium-pyrite interactions experiments were performed under an anoxic atmosphere, in a glove box. Pyrite dissolution under anoxic conditions releases sulfoxy-anions and iron(II), which can then be adsorbed on the pyrite surface. This adsorption was confirmed by interaction experiments using iron(II) isotopic dilution. Uranium(VI) is retained by an exchange reaction with iron(II) adsorbed on sulphur sites, with a maximal amount of sorbed uranium at pH {>=} 5.5. Cobalt(II) and europium(III) are also adsorbed on the pyrite surface above pH 5.5 confirming then that reduction is not required for species to adsorb on pyrite. When the concentration of uranium retained is lower than 4 x 10{sup -9} mol g{sup -1}, an oxidation-reduction reaction leads to the formation of a uranium (VI) (IV) mixed oxide and to solid sulphur (d.o. {>=} -I). During this reaction, iron remains mostly at the +II oxidation degree. The reaction products seem to passivate the pyrite surface: at higher amounts of retained uranium, the oxidation-reduction reaction is no longer observed. The surface is saturated by the retention of (3.4 {+-} 0.8) x 10{sup -7} mol L{sup -1} of uranium(VI). Modelling of uranium sorption at high surface coverage ({>=} 4 x 10{sup -9} mol g{sup -1}) by the Langmuir model yields an adsorption constant of 8 x 10{sup 7} L mol{sup -1}. Finally, a great excess of uranium(VI) above the

  2. Degradation Mechanism in a Direct Carbon Fuel Cell Operated with Demineralised Brown Coal

    International Nuclear Information System (INIS)

    Rady, Adam C.; Giddey, Sarbjit; Kulkarni, Aniruddha; Badwal, Sukhvinder P.S.; Bhattacharya, Sankar

    2014-01-01

    Graphical abstract: - Highlights: • Degradation mechanism studied for demineralised coal in a direct carbon fuel cell. • Diffusion limited processes dominate the electrode polarisation losses in pure N 2 . • Major fuel cell performance loss occurred due to loss of carbon/anode contacts. • The anode retained its phase structure with minor other phases formed in operation. - Abstract: The performance of a demineralised and devolatilised coal from the Morwell mine in the Latrobe Valley, Victoria, has been investigated in a direct carbon fuel cell (DCFC) operated at 850 °C. The focus of the investigation has been on understanding degradation issues as a function of time involving a sequence of electrochemical impedance spectroscopy and voltage-current characteristic. Diffusion limited processes dominate the electrode polarisation losses in pure N 2 atmosphere, however, these decrease substantially in the presence of CO 2 as the anode chamber purge gas, due to in situ generation of fuel species by the reaction of CO 2 with carbon. Post-mortem analysis of anode by SEM and XRD revealed only a minor degradation due to its reduction, particle agglomeration as well as the formation of small quantity of new phases. However, major fuel cell performance degradation (increase of ohmic resistive and electrode polarisation losses) occurred due to loss of carbon/anode contacts and a reduction in the electron-conducting pathways as the fuel was consumed. The investigations revealed that the demineralised coal char can be used as a viable fuel for DCFC, however, further developments on anode materials and fuel feed mechanism would be required to achieve long-term sustained performance

  3. Spot testing on mechanical characteristics of surrounding rock in gates of fully mechanized top-coal caving face

    Energy Technology Data Exchange (ETDEWEB)

    Xie Guang-xiang; Yang Ke; Chang Ju-cai [Anhui University of Science and Technology, Anhui (China). Department of Resource Exploration and Management Engineering

    2006-07-01

    The distribution patterns of mechanical characteristics for surrounding rock in the gateways of fully mechanized top-coal caving (FMTC) face were put forward by analyzing deep displacement, surface displacement, stress distribution and supports loading. The results show that the surrounding rock of the gateways lies in abutment pressure decrease zone near the working face, so that the support load decreases. But the deformations of supports and surrounding rock are very acute. The deformation of surrounding rock appears mainly in abutment pressure influence zone. Reasonable roadway supporting should control the deformation of surrounding rock in intense stage of mining influence. Supporting design ideas of tailentry and head entry should be changed from loading control to deformation control. 8 refs., 10 figs., 1 tab.

  4. Chemistry and phase evolution during roasting of toxic thallium-bearing pyrite.

    Science.gov (United States)

    Lopez-Arce, Paula; Garcia-Guinea, Javier; Garrido, Fernando

    2017-08-01

    In the frame of a research project on microscopic distribution and speciation of geogenic thallium (Tl) from contaminated mine soils, Tl-bearing pyrite ore samples from Riotinto mining district (Huelva, SW Spain) were experimentally fired to simulate a roasting process. Concentration and volatility behavior of Tl and other toxic heavy metals was determined by quantitative ICP-MS, whereas semi-quantitative mineral phase transitions were identified by in situ thermo X-Ray Diffraction (HT-XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) analyses after each firing temperature. Sample with initial highest amount of quartz (higher Si content), lowest quantity of pyrite and traces of jarosite (lower S content) developed hematite and concentrated Tl (from 10 up to 72 mg kg -1 ) after roasting at 900 °C in an oxidizing atmosphere. However, samples with lower or absent quartz content and higher pyrite amount mainly developed magnetite, accumulating Tl between 400 and 500 °C and releasing Tl from 700 up to 900 °C (from 10-29 mg kg -1 down to 4-1 mg kg -1 ). These results show the varied accumulative, or volatile, behaviors of one of the most toxic elements for life and environment, in which oxidation of Tl-bearing Fe sulfides produce Fe oxides wastes with or without Tl. The initial chemistry and mineralogy of pyrite ores should be taken into account in coal-fired power stations, cement or sulfuric acid production industry involving pyrite roasting processes, and steel, brick or paint industries, which use iron ore from roasted pyrite ash, where large amounts of Tl entail significant environmental pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Shale Failure Mechanics and Intervention Measures in Underground Coal Mines: Results From 50 Years of Ground Control Safety Research

    Science.gov (United States)

    2015-01-01

    Ground control research in underground coal mines has been ongoing for over 50 years. One of the most problematic issues in underground coal mines is roof failures associated with weak shale. This paper will present a historical narrative on the research the National Institute for Occupational Safety and Health has conducted in relation to rock mechanics and shale. This paper begins by first discussing how shale is classified in relation to coal mining. Characterizing and planning for weak roof sequences is an important step in developing an engineering solution to prevent roof failures. Next, the failure mechanics associated with the weak characteristics of shale will be discussed. Understanding these failure mechanics also aids in applying the correct engineering solutions. The various solutions that have been implemented in the underground coal mining industry to control the different modes of failure will be summarized. Finally, a discussion on current and future research relating to rock mechanics and shale is presented. The overall goal of the paper is to share the collective ground control experience of controlling roof structures dominated by shale rock in underground coal mining. PMID:26549926

  6. Rapid pyrolysis of Serbian soft brown coals

    Directory of Open Access Journals (Sweden)

    Jankes Goran

    2009-01-01

    Full Text Available Soft brown coals of the open coal fields of Kolubara and Kostolac are the main domestic energy sources of Serbia. This paper presents the results of investigations on rapid devolatilization of these two coals which have covered kinetics of devolatilization (based on total volatile yield, forms of sulphur and petrographic analysis of coal and char. Experiments of devolatilization were performed in inert gas (N2 at atmospheric pressure and in batch-type hot-wire screen reactor. The mass-loss values of both coals at selected final reaction temperatures (300-900°C and retention times (3-28 s were obtained. Anthony and Howard's kinetic model was applied over two temperature ranges (300-500 and 700-900°C. The types of sulphur as monosulphide, sulphate, pyritic, and organic sulphur were determined for chars and original coals. Strong transformation of pyrite was evident even at low temperatures (300°C. Devolatilization of all types of sulphur has started over 600 and at 900°C the content of sulphur in char remained only 66% of total sulphur in original coal. Microscopic investigations were carried out on samples prepared for reflected light measurements. The petrographic analysis included: the ratio of unchanged and changed coal, maceral types, the share of cenosferes, isotropic mixed carbonized grains, mixed grains, small fragments, clay, and pyrite. The change of the structure of devolatilized coal was also observed.

  7. Mercury concentration in coal - Unraveling the puzzle

    Science.gov (United States)

    Toole-O'Neil, B.; Tewalt, S.J.; Finkelman, R.B.; Akers, D.J.

    1999-01-01

    Based on data from the US Geological Survey's COALQUAL database, the mean concentration of mercury in coal is approximately 0.2 ??gg-1. Assuming the database reflects in-ground US coal resources, values for conterminous US coal areas range from 0.08 ??gg-1 for coal in the San Juan and Uinta regions to 0.22 ??gg-1 for the Gulf Coast lignites. Recalculating the COALQUAL data to an equal energy basis unadjusted for moisture differences, the Gulf Coast lignites have the highest values (36.4 lb of Hg/1012 Btu) and the Hams Fork region coal has the lowest value (4.8 lb of Hg/1012Btu). Strong indirect geochemical evidence indicates that a substantial proportion of the mercury in coal is associated with pyrite occurrence. This association of mercury and pyrite probably accounts for the removal of mercury with the pyrite by physical coal cleaning procedures. Data from the literature indicate that conventional coal cleaning removes approximately 37% of the mercury on an equal energy basis, with a range of 0% to 78%. When the average mercury reduction value is applied to in-ground mercury values from the COALQUAL database, the resulting 'cleaned' mercury values are very close to mercury in 'as-shipped' coal from the same coal bed in the same county. Applying the reduction fact or for coal cleaning to eastern US bituminous coal, reduces the mercury input load compared to lower-rank non-deaned western US coal. In the absence of analytical data on as-shipped coal, the mercury data in the COALQUAL database, adjusted for deanability where appropriate, may be used as an estimator of mercury contents of as-shipped coal. ?? 1998 Published by Elsevier Science Ltd. All rights reserved.

  8. THE DEPRESSION OF PYRITE FLOTATION BY THIOBACILLUS FERROOXIDANS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The experimental studies on the microbial flotation of a pure pyrite sample using Thiobacillus ferrooxidans was conducted in the laboratory. The results indicate that Thiobacillus ferrooaidans has strong depression effect on the flotation of pyrite. Thiobacillus f errooxidans can adsorb on the surface of pyrite in a very short time (a few min. ), changing the surface from hydrophobic into hydrophilic and making the pyrite particles to lose their floatability. Therefore, Thiobacillus ferrooxidans is an effective microbial depressant of pyrite. It has also been pointed out that the depression of pyrite by Thiobacillus ferrooxidans is caused by the adsorption of the microbial colloids, but not by the oxidation effect.

  9. Bugs and coal: processing fuels with biotechnology

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, M

    1987-06-01

    Bioprocessing of coal is developing along several fronts, each of potential significance to utilities. Researchers have found a fungus, polyporous versicolor, which can liquefy certain kinds of coal and scientists have genetically engineered bacteria that remove sulfur and ash-forming metal impurities from coal. Research programs are being undertaken to find organisms that will convert lignite into gaseous methane to produce gaseous fuel more economically than the current coal gasification methods. Researchers looking for ways to remove sulfur from coal before it is burned are evaluating the use of a bacterium called thiobacillus ferroxidans to enhance the physical removal of pyrite. 2 refs.

  10. Sorption mechanism of solvent vapors to coals; Sekitan eno yobai joki no shuchaku kiko no kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, K.; Takanohashi, T.; Iino, M. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

    1996-10-28

    With an objective to clarify the interactions between micropore structure of coal and solvent reagents, a sorption experiment was carried out under solvent saturated vapor pressure. Low-volatile bituminous coal, Pocahontas No. 3 coal, has the aromatic ring structure developed, and makes solvent more difficult to diffuse into coal, hence sorption amount is small. Methanol has permeated since its polarity is high. High-volatile bituminous coal, Illinois No. 6 coal, makes solvent penetrate easily, and the sorption amount was large with both of aromatic and polar solvents. Since brown coal, Beulah Zap coal, contains a large amount of oxygen, and hydrogen bonding is predominant, sorption amount of cyclohexane and benzene having no polarity is small. Methanol diffuses while releasing hydrogen bond due to its polarity, and its sorption amount is large. A double sorption model is available, which expresses the whole sorption amount as a sum of physical sorption amount and amount of permeation into coal. This model was applied when it explained successfully the sorption behavior of the solvents relative to coals, excepting some of the systems. However, also observed were such abnormal behavior as sorption impediment due to interactions between coal surface and solvents, and permeation impediment due to hydroxyl groups inside the coals. 1 ref., 10 figs., 2 tabs.

  11. The determination of uranium in pyrite samples

    International Nuclear Information System (INIS)

    Jacobs, J.J.

    1979-01-01

    An existing method for the determination of uranium in rocks and minerals is examined for the determination of uranium in materials containing pyrite. The results are comparable with those obtained by a spectrophotometric method, the precision (relative standard deviation) of the method for standards with U 3 O 8 contents of 1500 and 300 p.p.m. being 0,03 and 0,08 respectively when prepared in pyrite, and 0,15 and 0,06 respectively when made up with inert diluent. Full details of the procedure are given in accompanying appendices [af

  12. A combined chemical, isotopic and microstructural study of pyrite from roll-front uranium deposits, Lake Eyre Basin, South Australia

    Science.gov (United States)

    Ingham, Edwina S.; Cook, Nigel J.; Cliff, John; Ciobanu, Cristiana L.; Huddleston, Adam

    2014-01-01

    The common sulfide mineral pyrite is abundant throughout sedimentary uranium systems at Pepegoona, Pepegoona West and Pannikan, Lake Eyre Basin, South Australia. Combined chemical, isotopic and microstructural analysis of pyrite indicates variation in fluid composition, sulfur source and precipitation conditions during a protracted mineralization event. The results show the significant role played by pyrite as a metal scavenger and monitor of fluid changes in low-temperature hydrothermal systems. In-situ micrometer-scale sulfur isotope analyses of pyrite demonstrated broad-scale isotopic heterogeneity (δ34S = -43.9 to +32.4‰VCDT), indicative of complex, multi-faceted pyrite evolution, and sulfur derived from more than a single source. Preserved textures support this assertion and indicate a genetic model involving more than one phase of pyrite formation. Authigenic pyrite underwent prolonged evolution and recrystallization, evidenced by a genetic relationship between archetypal framboidal aggregates and pyrite euhedra. Secondary hydrothermal pyrite commonly displays hyper-enrichment of several trace elements (Mn, Co, Ni, As, Se, Mo, Sb, W and Tl) in ore-bearing horizons. Hydrothermal fluids of magmatic and meteoric origins supplied metals to the system but the geochemical signature of pyrite suggests a dominantly granitic source and also the influence of mafic rock types. Irregular variation in δ34S, coupled with oscillatory trace element zonation in secondary pyrite, is interpreted in terms of continuous variations in fluid composition and cycles of diagenetic recrystallization. A late-stage oxidizing fluid may have mobilized selenium from pre-existing pyrite. Subsequent restoration of reduced conditions within the aquifer caused ongoing pyrite re-crystallization and precipitation of selenium as native selenium. These results provide the first qualitative constraints on the formation mechanisms of the uranium deposits at Beverley North. Insights into

  13. Relation of ash composition to the uses of coal

    Energy Technology Data Exchange (ETDEWEB)

    Fieldner, A C; Selvig, W A

    1926-02-01

    The effects of coal ash and ash components on the utilization of coal for coke and gas production, steam generation, water gas production, smithing, and domestic uses were described in a review of literature. Calcite, gypsum, and pyrite which occur in high amounts in coal, increase the ash fusibility of the coal and render it unsuitable for many industrial and domestic uses. As a rule, coal ash of high Si content and low Fe content would not be readily fusible. High amounts of ash in coal also have the effect of reducing the heating value of the coal.

  14. Bioprocessing of coal - 10 - an application of microbial flotation to mineral processing

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, T. [and others] [CRIEPI, Abiko-shi (Japan). Abiko Research Lab.

    1996-09-01

    Microbial flotation for coal desulfurization is being developed. Pyrite in coal is removed by bacterial adhesion by changing the surface property of pyrite. The bacterial adhesion of Thiobacillus ferrooxidans to sulfide minerals (pyrite, galena, molybdenite, chalcocite and millerite), and pyrite removal from the mixture of these sulfide minerals by microbial flotation was investigated. To compare the adhesion of T. ferrooxidans to pyrite with that to the other four minerals mentioned, the surface areas of the minerals, where the bacterium could adhere, was measured. It was observed that the roughness on the mineral surfaces was much smaller than the size of the bacterial cells. Hence, it was suggested that the roughness did not affect the bacterial adhesion to mineral surfaces. Bacterial adhesion to pyrite was compared with that to the other minerals. The amount of adhering bacterium was estimated on the basis of the adherable surface area measured with microscopic method. The amount of adhering cells to pyrite was 421.6 x 10{sup 8} cells/cm{sup 2}. On the other hand, the amounts of adhering cells to the minerals, except for pyrite were in a range of 77.1 to 160.8 x 10{sup 8} cells/cm{sup 2}. The bacterium adheres more to pyrite than to the other minerals, and only adheres to pyrite even if the pyrite is mixed with other minerals. Hence, T. ferrooxidans could adhere selectively to pyrite. Pyrite removal from the mineral mixtures was investigated with microbial flotation. Pyrite removal was in a range of 83.7% to 95.1% and mineral recovery was 72.9% to 100%. The grade of recovered minerals was in a range of 79.2 to 86.0% and that of rejected pyrite was in a range of 78.7 to 90.0%. These results suggest that microbial flotation can be a novel technology for mineral processing.

  15. Preparation of natural pyrite nanoparticles by high energy planetary ball milling as a nanocatalyst for heterogeneous Fenton process

    Energy Technology Data Exchange (ETDEWEB)

    Fathinia, Siavash [Department of Mining Engineering, Faculty of Engineering and Technology, Imam Khomeini International University, Qazvin (Iran, Islamic Republic of); Research Laboratory of Advanced Water and Wastewater Treatment Processes, Department of Applied Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of); Fathinia, Mehrangiz [Research Laboratory of Advanced Water and Wastewater Treatment Processes, Department of Applied Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of); Rahmani, Ali Akbar [Department of Mining Engineering, Faculty of Engineering and Technology, Imam Khomeini International University, Qazvin (Iran, Islamic Republic of); Khataee, Alireza, E-mail: a_khataee@tabrizu.ac.ir [Research Laboratory of Advanced Water and Wastewater Treatment Processes, Department of Applied Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2015-02-01

    Graphical abstract: - Highlights: • Pyrite nanoparticles were successfully produced by planetary ball milling process. • The physical and chemical properties of pyrite nanoparticles were fully examined. • The degradation of AO7 was notably enhanced by pyrite nanoparticles Fenton system. • The influences of basic operational parameters were investigated using CCD. - Abstract: In the present study pyrite nanoparticles were prepared by high energy mechanical ball milling utilizing a planetary ball mill. Various pyrite samples were produced by changing the milling time from 2 h to 6 h, in the constant milling speed of 320 rpm. X-ray diffraction (XRD), scanning electron microscopy (SEM) linked with energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR) analysis and Brunauer–Emmett–Teller (BET) were performed to explain the characteristics of primary (unmilled) and milled pyrite samples. The average particle size distribution of the produced pyrite during 6 h milling was found to be between 20 nm and 100 nm. The catalytic performance of the different pyrite samples was examined in the heterogeneous Fenton process for degradation of C.I. Acid Orange 7 (AO7) solution. Results showed that the decolorization efficiency of AO7 in the presence of 6 h-milled pyrite sample was the highest. The impact of key parameters on the degradation efficiency of AO7 by pyrite nanoparticles catalyzed Fenton process was modeled using central composite design (CCD). Accordingly, the maximum removal efficiency of 96.30% was achieved at initial AO7 concentration of 16 mg/L, H{sub 2}O{sub 2} concentration of 5 mmol/L, catalyst amount of 0.5 g/L and reaction time of 25 min.

  16. The effect of CO{sub 2} saturation on mechanical properties of Australian black coal using acoustic emission

    Energy Technology Data Exchange (ETDEWEB)

    P.G. Ranjit; D. Jasinge; S.K. Choi; M. Mehic; B. Shannon [Monash University (Australia). Department of Civil Engineering

    2010-08-15

    Acoustic emission (AE) methods are now widely used for damage evaluation. For a better understanding of the damage mechanics of materials such as rocks, AE has been used to monitor stresses which induce crack closure, crack initiation and crack damage. In the present study, an AE system was used to study the damage behaviour of some Australian black coal samples subjected to uniaxial compression. Several samples were left in a container filled with 100% carbon dioxide (CO{sub 2}) at a certain pressure for 72 h prior to testing. The results were compared with samples which had only been exposed to the atmosphere to see if CO{sub 2} had any adverse effect on the strength of coal. Strain gauges were installed on the samples and the measured axial and volumetric strains were studied in conjunction with the AE counts. The AE method was successfully used for detecting the onset of crack initiation and the crack damage stress threshold of the black coal samples. Of the coal samples examined, crack initiation and crack closure of the samples subjected to saturation with CO{sub 2} occurred at stress corresponding to a higher percentage of the peak strength when compared to the samples which had only been exposed to atmospheric conditions. However, crack damage occurred at a higher percentage of peak strength and the average peak strength showed a higher value for samples in atmospheric condition when compared to CO{sub 2} saturated samples. The results show that sorption of CO{sub 2} can cause a reduction in strength of the black coal samples when tested under uniaxial compression. As the coal samples were highly inhomogeneous more tests are required in order to be able to confirm whether the adsorption of CO{sub 2} will cause strength reduction in coal and to identify the actual underlying mechanisms. 36 refs., 8 figs., 2 tabs.

  17. Fabrication and characterization of PDLLA/pyrite composite bone ...

    Indian Academy of Sciences (India)

    Polylactic acid; Chinese herbal medicine; pyrite; scaffold; bone regeneration; cell culture. 1. Introduction ... research focuses on the direct cellular level effect of pyrite on bone cells. ..... optimal scaffold from the results of this paper. Although the.

  18. Investigations into stress shell characteristics of surrounding rock in fully mechanized top-coal caving face

    Energy Technology Data Exchange (ETDEWEB)

    Xie, G.X.; Chang, J.C.; Yang, K. [Anhui University of Science and Technology, Huainan (China)

    2009-01-15

    A key issue in underground mining is to understand and master the evolving patterns of stress induced by mining, and to control and utilize the action of rock pressure. Numerical and physical modeling tests have been carried out to investigate the distribution patterns of stress in the rock surrounding a fully mechanized top-coal caving (FMTC) face. The results showed that a macro-stress shell composed of high stress exists in the rock surrounding an FMTC face. The stress of the shell is higher than its internal and external stress and the stresses at its skewback producing abutment pressure for the surrounding rock. The stress shell lies in the virgin coal and rock mass in the vicinity of the face and its sagging zone. The stress shell, which bears and transfers the loads of overlying strata, acts as the primary supporting system of forces, and is the corpus of characterizing three-dimensional and macro-rock pressure distribution of mining face. Its external and internal shape changes with the variations in the working face structure as the face advances. Within the low-stress zone inside the stress shell, another structure, i.e. voussoir beam, which only bears parts of the load from the lower-lying strata, will produce periodic pressures on the face instead of great dynamic pressure even if the beam ruptures and loses stability. The results show that the FMTC face is situated within the lower-stress zone, which is protected by the stress shell of the overlying surrounding rock. We give an explanation of lower occurrence of rock pressure on FMTC faces, and reveal the mechanical nature of the top coal of an FMTC face acting as a 'cushion'. The strata behaviors of the face and its neighboring gates are under control of the stress shell. Drastic rock pressure in mine may occur when the balance of the stress shell is destruction or the forces system of the stress shell transfers. Crown Copyright

  19. Mechanism of Enhancing Extraction of Vanadium from Stone Coal by Roasting with MgO

    Directory of Open Access Journals (Sweden)

    Fang Chen

    2017-02-01

    Full Text Available In this paper, the extraction of vanadium from stone coal by roasting with MgO and leaching with sulfuric acid has been investigated, and the mechanism analysis of stone coal roasting with MgO was studied. The results indicated that under the conditions that the mass fraction of the particles with grain size of 0–0.074 mm in raw ore was 75%, the roasting temperature was 500 °C, the roasting time was 1 h, MgO addition was 3 wt %, the sulfuric acid concentration was 20 vol %, the liquid-to-solid ratio was 1.5 mL/g, the leaching temperature was 95 °C, and leaching time was 2 h, resulting in a vanadium leaching efficiency of 86.63%, which increased by 7.73% compared with that of blank roasting. The mechanism analysis showed that the degree of calcite decomposition was low and, thus, magnesium vanadate was more easily formed than calcium vanadate below 500 °C. Moreover, magnesium vanadate was easier to dissolve than calcium vanadate during the sulfuric acid leaching process. Thus, the vanadium leaching efficiency was enhanced by using MgO as a roasting additive below 500 °C. Additionally, at high temperature the formation of tremolite would consume calcium oxide produced from the decomposition of calcite, thus, the formation of calcium vanadate was hindered, and V2O5 would react with MgO to form magnesium vanadate. Therefore, the vanadium leaching efficiency of roasting with MgO was higher than that of blank roasting at high temperature.

  20. Mechanical model of water inrush from coal seam floor based on triaxial seepage experiments

    Institute of Scientific and Technical Information of China (English)

    Yihui Pang; Guofa Wang; Ziwei Ding

    2014-01-01

    In order to study the mechanism of confined water inrush from coal seam floor, the main influences on permeability in the process of triaxial seepage experiments were analyzed with methods such as laboratory experiments, theoretical analysis and mechanical model calculation. The crack extension rule and the ultimate destruction form of the rock specimens were obtained. The mechanism of water inrush was explained reasonably from mechanical point of view. The practical criterion of water inrush was put forward. The results show that the rock permeability ‘‘mutation’’ phe-nomenon reflects the differences of stress state and cracks extension rate when the rock internal crack begins to extend in large-scale. The rock ultimate destruction form is related to the rock lithology and the angle between crack and principal stress. The necessary condition of floor water inrush is that the mining pressure leads to the extension and transfixion of the crack. The sufficient condition of floor water inrush is that the confined water’s expansionary stress in normal direction and shear stress in tangential direction must be larger than the internal stress in the crack. With the two conditions satisfied at the same time, the floor water inrush accident will occur.

  1. Pyritized ooids from the Arabian Sea basin

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, P.S.; Rao, Ch.M.; Reddy, N.P.C.

    Pyritized ooids in association with turbidites were observed in a box core collected at a depth of 3627 m from the Arabian Sea Basin. Ooids having a shallow water origin were transported to the present depth by turbidity currents or slumping...

  2. Nucleic acid interactions with pyrite surfaces

    International Nuclear Information System (INIS)

    Mateo-Marti, E.; Briones, C.; Rogero, C.; Gomez-Navarro, C.; Methivier, Ch.; Pradier, C.M.; Martin-Gago, J.A.

    2008-01-01

    The study of the interaction of nucleic acid molecules with mineral surfaces is a field of growing interest in organic chemistry, origin of life, material science and biotechnology. We have characterized the adsorption of single-stranded peptide nucleic acid (ssPNA) on a natural pyrite surface, as well as the further adsorption of ssDNA on a PNA-modified pyrite surface. The characterization has been performed by means of reflection absorption infrared spectroscopy (RAIRS), atomic force microscopy (AFM) and X-ray photoemission spectroscopy (XPS) techniques. The N(1s) and S(2p) XPS core level peaks of PNA and PNA + DNA have been decomposed in curve-components that we have assigned to different chemical species. RAIRS spectra recorded for different concentrations show the presence of positive and negative adsorption bands, related to the semiconducting nature of the surface. The combination of the information gathered by these techniques confirms that PNA adsorbs on pyrite surface, interacting through nitrogen-containing groups of the nucleobases and the iron atoms of the surface, instead of the thiol group of the molecule. The strong PNA/pyrite interaction inhibits further hybridization of PNA with complementary ssDNA, contrary to the behavior reported on gold surfaces

  3. Nucleic acid interactions with pyrite surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mateo-Marti, E. [Centro de Astrobiologia (CSIC-INTA), Ctra. Ajalvir, Km. 4, 28850-Torrejon de Ardoz, Madrid (Spain)], E-mail: mateome@inta.es; Briones, C.; Rogero, C. [Centro de Astrobiologia (CSIC-INTA), Ctra. Ajalvir, Km. 4, 28850-Torrejon de Ardoz, Madrid (Spain); Gomez-Navarro, C. [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049-Madrid (Spain); Methivier, Ch.; Pradier, C.M. [Laboratoire de Reactivite de Surface, UMR CNRS 7609. Universite Pierre et Marie Curie, 4, Pl Jussieu, 75005-Paris (France); Martin-Gago, J.A. [Centro de Astrobiologia (CSIC-INTA), Ctra. Ajalvir, Km. 4, 28850-Torrejon de Ardoz, Madrid (Spain); Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049-Madrid (Spain)

    2008-09-03

    The study of the interaction of nucleic acid molecules with mineral surfaces is a field of growing interest in organic chemistry, origin of life, material science and biotechnology. We have characterized the adsorption of single-stranded peptide nucleic acid (ssPNA) on a natural pyrite surface, as well as the further adsorption of ssDNA on a PNA-modified pyrite surface. The characterization has been performed by means of reflection absorption infrared spectroscopy (RAIRS), atomic force microscopy (AFM) and X-ray photoemission spectroscopy (XPS) techniques. The N(1s) and S(2p) XPS core level peaks of PNA and PNA + DNA have been decomposed in curve-components that we have assigned to different chemical species. RAIRS spectra recorded for different concentrations show the presence of positive and negative adsorption bands, related to the semiconducting nature of the surface. The combination of the information gathered by these techniques confirms that PNA adsorbs on pyrite surface, interacting through nitrogen-containing groups of the nucleobases and the iron atoms of the surface, instead of the thiol group of the molecule. The strong PNA/pyrite interaction inhibits further hybridization of PNA with complementary ssDNA, contrary to the behavior reported on gold surfaces.

  4. Genesis of uranium-gold pyritic conglomerates

    International Nuclear Information System (INIS)

    Myers, W.B.

    1981-01-01

    The ancient pyritic ore conglomerates have a common origin best exemplified by the Witwatersrand deposits. All contain detrital pyrite and uraninite, which are unstable in modern oxygenated environments and were deposited in a reducing atmosphere. The Rand reefs are not similar to modern gold placers. Placers result from the near incapacity of streams and currents to transport coarse gold. Placers as rich as Rand reef occur only in narrow paystreaks within 15 kilometers of a coarse-gold source. The board dispersion of gold in the reefs is due to solution transport of metal complexed as aurous sulfide, leached anoxygenically from crustal rocks, probably from sea-floor basalt, and precipitated by a slow reaction driven by the radioactive decay of detrital uraninite. Radiolysis of water on shallow marine unconformities resulted in diffusion of hydrogen to the atmosphere and a slight excess of hydroxyl free radical in the reef environment. The mild oxidizing tendency slowly dissolved uranium, precipitated gold, and oxygenated thucholite. These actions define a maturing process. A uraninite placer accumulating on an unconformity becomes progressively converted to a gold reef with little residual uraninite. The most mature reefs tend to grade toward the thucholite-seam type, very thin but exceedingly rich in gold. A combination of chemical attack and physical reworking accounts for the general thinness of mature reefs. Pyrite, like uraninite, decreases in abundance with increasing maturity; buffering by pyrite moderated the oxidative depletion of uranium. Where pyrite was scanty or absent, uraninite was completely dissolved by the effects of radiolysis and no ore formed

  5. Treatment of Egyptian Maghara coal by plasma ozone synthesized by silent discharge

    CERN Document Server

    Salem, M A; Garamoon, A A; Hassouba, M A

    2003-01-01

    A sample of pyrite rich bituminous coal collected from the main coal seam of Maghara mine, northern sinai, was treated by ozone plasma. The latter was synthesized using silent discharge method (10 kv a.c. and 50 hz). The room temperature Moessbauer spectra of untreated coal sample was easily fitted to two doublet, whose parameters matched those of pyrite (FeS sub 2) and sulfate (FeSO sub 4.H sub 2 O) in addition to hematite. After treatment by ozone plasma, a doublet ascribed to pyrite was observed. The extent of pyrite oxidation to jarosite (Fe sub 2 (SO sub 4) sub 3. nH sub 2 O) was monitored by their relative spectral areas, the incomplete oxidation of pyrite may be attributed to the presence of calcium sulfate layer which acts a screen of ozone.

  6. Action time effect of lime on its depressive ability for pyrite

    Institute of Scientific and Technical Information of China (English)

    Tichang Sun

    2004-01-01

    Two sample groups of bulk concentrates consisting mainly of pyrite and chalcopyrite from Daye and Chenghchao Mines in Hubei Province of China were used to investigate the effect of the action time of lime on its depressive ability for pyrite. The experimental results conducted with different samples and collectors showed that the action time between lime and pyrite markedly influences the depressive ability of lime. The depressive ability of lime increased with the action time increasing. It was also proved that the depressive results obtained at a large lime dosage after a shorter action time are similar to those obtained at a small lime dosage after a longer action time. The increase of depressive ability of lime after a longer action time is because that there are different mechanisms in different action time. The composition on the surface of pyrite acted for different time with lime was studied by using ESCA (Electron Spectroscopic Chemical Analysis). The results showed that iron hydroxide and calcium sulphate formed on the pyrite surface at the presence of lime in the pulp but the amounts of iron hydroxide and calcium sulphate were different at different action time. At the beginning action time the compound formed on the pyrite surface was mainly calcium sulphate and almost no iron hydroxide formed; but with the action time increasing, iron hydroxide formed. The longer the action time, the more iron hydroxide and the less calcium sulphate formed. It was considered that the stronger depressive ability of lime after a longer action time is because more iron hydroxide forms on the pyrite surface.

  7. ORGANIZATIONAL AND ECONOMIC MECHANISM OF MANAGING COMPETITIVENESS OF THE COAL-MINING ENTERPRISE

    Directory of Open Access Journals (Sweden)

    Viktoriya V. Dyachkova

    2017-06-01

    Full Text Available In the present article the authors propose the organizational and economic mechanism of managing competitiveness of the coal-mining enterprise. This mechanism has been worked out on the basis of the analysis of business processes of competitiveness management in mines of the Donbass region with the aim of supporting, arranging and managing effectively these processes. During the research the common faults complicating exact and timely assessment of competitiveness of the enterprise were revealed and the structural and functional model of business processes was offered. This model includes a complex of actions with a certain algorithm of the actions aimed to increase the level of competitiveness by assessment of the current level of enterprise’s competitiveness, to identify strengths andweaknesses of the enterprise, and to elaborate the strategy of subsequent implementation. The basis of the proposed mechanism is represented by economic and mathematical model of competitiveness assessment. This model includes the use of the method for assessing the enterprise’s competitiveness on the basis of three indicators: 1 financial and economic conditions; 2 production and technological conditions; 3 mining-and-geological conditions. This model gained further development in the treelike structure of factors and indicators for ensuring the possibility of identification of the priority directions and problems of enterprise’s activity. As a result, the authors proposed the method of defining disproportions among current and potential opportunities of the enterprise by modeling a sample enterprise, and also the method of definition of stability of the enterprise by comparison of competitiveness indicators for the last and report period. The last stage of formation of the organizational and economic mechanism of management of competitiveness of the coal-mining enterprise is development of a matrix of the choice of the development strategy of the

  8. A study on the reduction in the production cost of the long-running collieries and mechanization of coal mining

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Shik; Hong, Jee Sang; Lee, Kyung Woon; Kim, Oak Hwan; Kim, Dae Kyung [Korea Inst. of Geology Mining and Materials, Taejon (Korea, Republic of)

    1995-12-01

    The reducing coal market has been enforcing the coal industry to make exceptional rationalization and restructuring efforts since the end of the eighties. To the competition from crude oil and natural gas has been added the growing pressure from rising wages and production cost. To improve the competitive position of the coal mines against oil and gas through cost reduction, studies on mining technology have been carried out. Investigations and analyses on the technologies used in Hanbo Colliery which was designated one of the long term running mines were done and recommendations were made. And also a site test of plough were implemented at the KyungDong Colliery. The mechanization program of 1994 were analyzed and evaluated separately. (author). 38 refs.

  9. Role of non-ferrous coal minerals and by-product metallic wastes in coal liquefaction. Technical progress report, June 1, 1980-August 31, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Garg, D; Givens, E N; Schweighardt, F K; Clinton, J H; Tarrer, A R; Guin, J A; Curtis, C W; Huang, W J; Shridharani, K

    1980-09-01

    Additional data on the pyrite catalysis of liquefaction of Elkhorn number 3 coal are presented. The liquefaction of Elkhorn number 3 coal was significantly catalyzed by the presence of pyrite. Coal conversion, oil yield and preasphaltene conversion all increased when pyrite was added. An increase in hydrocarbon gas make accompanied by a higher hydrogen consumption were also observed. The higher activity in the presence of pyrite could be utilized by running the liquefaction step at milder conditions which would mean a lower gas make. Although we had heard reports that sulfur elimination from the SRC was improved by use of pyrite, our data showed only very small changes. Nitrogen removal from the solvent, however, was definitely observed. At 850/sup 0/F nitrogen in the oil product went from 1.61 to 1.12 on adding pyrite. This increased nitrogen removal was also seen in the added ammonia yields. Kentucky number 9 coal also responded very well to the presence of pyrite. Conversions and oil yields increased while the hydrocarbon yields decreased at both temperatures that were tested, i.e., 825 and 850/sup 0/F. Hydrogen consumptions also increased. In the screening program the results from testing a number of materials are reported. None of the zeolites gave any significant improvement over coal itself. The iron, molybdenum, nickel, and cobalt rich materials had significant activity, all 85 to 90% conversion with high oil yields.Among materials specifically reported this period the clays failed to show any significant catalytic effect.

  10. Sumpor u ugljenu (Sulphur in Coal

    Directory of Open Access Journals (Sweden)

    Rađenović, A.

    2004-12-01

    Full Text Available The presence of sulphur in coal possesses important environmetal problems in its usage. The sulphur dioxide (S02 emissions produced during coal combustion account for a significant proportion of the total global output of anthropogenic SO2. The extent of sulphur separation depends on several variables such as the form of sulphur in coal, intimacy of contact between minerals and the products of devolatilization. The total sulphur in coal varies in the range of 0.2 - 11 wt %, although in most cases it is beetwen 1 and 3 wt %. Sulphur occurs in a variety of both inorganic and organic forms. Inorganic sulphur is found mainly as iron pyrite, marcasite, pyrrhotite, sphalerite, galena, chalcopirite and as sulphates (rarely exceeds w = 0,1 %. Organic sulphur is found in aromatic rings and aliphatic functionalities usually as mercaptans, aliphatic and aryl sulfides, disulfides and thiophenes. Organic and pyritic sulphur quantities depend on coal rank. Higher rank coals tend to have a high proportion of labile sulphur. All the organic sulphur is bivalent and it is spread throughout the organic coal matrix. Sulphur occurs in all the macerals and most minerals. Vitrinite contains the major part of organic sulphur and metals. Elemental sulphur is produced during coal weathering. The depolymerization methods as pyrolysis and hydrogenation are very drastic methods wich change the structure of the coal and the sulphur groups. In the case of pyrolysis, high levels of desulphurization, in chars and additional production of liquid hydrocarbon can be achieved. Thiophenes and sulphides were the major sulphur components of tars from coal pyrolysis. Hyrdogen sulphide and the lower mercaptans and sulphides were found in the volatile matters. Hydrogen sulphide and thiophenes are practically the only sulphur products of coal hydrogenation. H2S is produced in char hydrodesulphurization. A number of options are available for reducing sulphur emissions including the

  11. Deformation mechanisms in a coal mine roadway in extremely swelling soft rock.

    Science.gov (United States)

    Li, Qinghai; Shi, Weiping; Yang, Renshu

    2016-01-01

    The problem of roadway support in swelling soft rock was one of the challenging problems during mining. For most geological conditions, combinations of two or more supporting approaches could meet the requirements of most roadways; however, in extremely swelling soft rock, combined approaches even could not control large deformations. The purpose of this work was to probe the roadway deformation mechanisms in extremely swelling soft rock. Based on the main return air-way in a coal mine, deformation monitoring and geomechanical analysis were conducted, as well as plastic zone mechanical model was analysed. Results indicated that this soft rock was potentially very swelling. When the ground stress acted alone, the support strength needed in situ was not too large and combined supporting approaches could meet this requirement; however, when this potential released, the roadway would undergo permanent deformation. When the loose zone reached 3 m within surrounding rock, remote stress p ∞ and supporting stress P presented a linear relationship. Namely, the greater the swelling stress, the more difficult it would be in roadway supporting. So in this extremely swelling soft rock, a better way to control roadway deformation was to control the releasing of surrounding rock's swelling potential.

  12. Converting coal

    Energy Technology Data Exchange (ETDEWEB)

    Avigliano, A. [Bedeschi (Italy)

    2006-10-15

    In September 2005, Bedeschi was commissioned to design and supply a coal unloading, conveying and storage facility for a new raw coal line system within Hatien II Cement Co. The new plant is composed of a grab unloader, a conveyor system, a storage shed with stacking and reclaiming facilities, a complete dedusting system and civil and steel structure engineering. The scope of supply includes a local fabrication portion; however, main components will be imported. The project will be completed in 21 months. The paper looks into the mechanics of loading and unloading coal. 4 figs., 4 photos.

  13. Mechanism underlying the action of waterglass in the flotation of Karaganda coals

    Energy Technology Data Exchange (ETDEWEB)

    Vlasova, N S; Shchegoleva, E N

    1979-05-01

    The effectiveness of activated waterglass in the flotation of coals containing a considerable amount of clay is governed basically by the selectivity of the silicic acid and its dissociation products in relation to the coal surface and the surface of the dirt, as well as its stability and the degree of hydration of the fixed layer of reagent.

  14. Mechanism of the action of water glass in the flotation of Karaganda coals

    Energy Technology Data Exchange (ETDEWEB)

    Vlasova, N S; Shchegoleva, E N

    1979-01-01

    The effectiveness of activated waterglass in the flotation of coals containing a considerable amount of clay is governed basically by the selctivity of the silicic acid and its dissociation products in relation to the coal surface and the surface of the dirt, as well as its stability and the degree of hydration of the fixed layer of reagent.

  15. Pyrite Passivation by Triethylenetetramine: An Electrochemical Study

    Directory of Open Access Journals (Sweden)

    Yun Liu

    2013-01-01

    Full Text Available The potential of triethylenetetramine (TETA to inhibit the oxidation of pyrite in H2SO4 solution had been investigated by using the open-circuit potential (OCP, cyclic voltammetry (CV, potentiodynamic polarization, and electrochemical impedance (EIS, respectively. Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that the inhibition efficiency is more pronounced with the increase of TETA. The data from potentiodynamic polarization show that the inhibition efficiency (η% increases from 42.08% to 80.98% with the concentration of TETA increasing from 1% to 5%. These results are consistent with the measurement of EIS (43.09% to 82.55%. The information obtained from potentiodynamic polarization also displays that the TETA is a kind of mixed type inhibitor.

  16. 40Ar/39Ar dating of pyrite

    International Nuclear Information System (INIS)

    York, D.; Masliwec, A.; Kuybida, P.; Hanes, J.A.; Hall, C.M.; Kenyon, W.J.; Spooner, E.T.C.; Scott, S.D.

    1982-01-01

    To overcome difficulties encountered in the customary method of determining the age of mineralization of sulphide ore deposits by analysing silicate material, the sulphide minerals themselves have been examined to see if they contained sufficient potassium and argon for 40 Ar/ 39 Ar age determination. Initial results indicate that this is the case for pyrite from the Geco ore body in northwestern Ontario, Canada. (U.K.)

  17. In situ characterization of natural pyrite bioleaching using electrochemical noise technique

    Science.gov (United States)

    Chen, Guo-bao; Yang, Hong-ying; Li, Hai-jun

    2016-02-01

    An in situ characterization technique called electrochemical noise (ECN) was used to investigate the bioleaching of natural pyrite. ECN experiments were conducted in four active systems (sulfuric acid, ferric-ion, 9k culture medium, and bioleaching solutions). The ECN data were analyzed in both the time and frequency domains. Spectral noise impedance spectra obtained from power spectral density (PSD) plots for different systems were compared. A reaction mechanism was also proposed on the basis of the experimental data analysis. The bioleaching system exhibits the lowest noise resistance of 0.101 MΩ. The bioleaching of natural pyrite is considered to be a bio-battery reaction, which distinguishes it from chemical oxidation reactions in ferric-ion and culture-medium (9k) solutions. The corrosion of pyrite becomes more severe over time after the long-term testing of bioleaching.

  18. Bacterial leaching of pyritic gold ores

    International Nuclear Information System (INIS)

    Gagliardi, F.M.; Cashion, J.D.; Brown, J.; Jay, W.H.

    1998-01-01

    Full text: Pyritic ores (pyrite and arsenopyrite) containing gold concentrations in excess of 50g Au/t can be processed to recover the gold by the removal of the sulphur from the ore. This may be achieved by roasting (producing sulphur dioxide emissions), pressure oxidation (expensive and suitable for large high grade deposits), pressure leaching (still currently being developed) or bacterial oxidation. The bacterial oxidation process is a well known process in nature but has only recently come under investigation as a economically viable and relatively clean method of gold recovery from deep low grade sulphidic ores. Samples were obtained from the Wiluna Gold Mine in Western Australia consisting of the original ore, six successive bacterial reactors and the final products. Moessbauer experiments have been performed at room temperature, liquid nitrogen and liquid helium temperatures, and in applied magnetic fields. The main components of the iron phases which were present during the bacterial treatment were pyrite and arsenopyrite which were readily oxidised by the bacteria. Ferric sulfates and ferric arsenates were identified as by-products of the process with a small amount of the oxyhydroxide goethite. These results are in contrast to the similar study of the Fairview Mine in South Africa where principally Fe(II) species were observed

  19. Microprobe channeling analysis of pyrite crystals

    International Nuclear Information System (INIS)

    Jamieson, D.N.; Ryan, C.G.

    1992-01-01

    Nuclear microprobe analysis has provided much useful information about the composition of microscopic inclusions in minerals, mainly through the use of Particle Induced X-ray Emission (PIXE). However this technique, while powerful, does not provide any direct information about the chemical state, in particular the lattice location, of the elements in the mineral. This information is often of crucial importance in understanding the ore genesis. The technique of ion channeling may be used to identify lattice location, but many minerals occur as microscopic crystals. Therefore it is necessary to utilize a nuclear microprobe with the technique of Channeling Contrast Microscopy (CCM). As many minerals contain interesting trace elements, it is necessary to measure both the yield of backscattered particles and the induced x-rays to get a clear picture of the lattice location of the elements in the crystal. CCM with PIXE was used to analyse natural pyrite crystals containing a variety of substitutional and non-substitutional elements and natural pyrite crystals from a gold bearing ore. In the latter case, evidence was obtained for two habits for Au in the 400 μm crystals: one as inclusions of Au rich minerals, the other substituted on the pyrite lattice sites. 31 refs., 3 tabs., 6 figs

  20. XAS studies on selenite reduction by pyrite

    International Nuclear Information System (INIS)

    Kang Mingliang; Liu Chunli; Chen Fanrong; Charlet, Laurnet

    2012-01-01

    The interaction of aqueous Se (IV) with pyrite were systematically investigated in light of thermodynamic calculations and X-ray Absorption Spectroscopy (XAS). The results from the speciation study reveal that the reduction product is Se (O) when natural pyrite reacts with Se (N) at pH≤5.65, while small amount of FeSeO 3 or iron selenides may be formed at pH 6.1. At pH≥6.94, due to the precipitation of Fe (Ⅲ) -oxyhydroxide, the formation of the thermodynamically most stable species, FeSe 2 , is inhibited. However, when the reactive nanopyrite-greigite was used for reaction, the thermodynamically most stable species, FeSe 2 , was found for the first time as the predominant product in the present study, suggesting that 79 Se can be immobilized in its most insoluble form, FeSe 2 , in Fe (Ⅱ) -sulfide containing environment. This study confirms that pyrite can significantly attenuate the mobility of Se by reductive precipitation, and that the reaction process does not produce protons under acidic or neutral condition when Se (O) is formed. (authors)

  1. Evaluation of pyrite and pyrrhotite in concretes

    Directory of Open Access Journals (Sweden)

    A. P. Marcelino

    Full Text Available ABSTRACT It is well known that aggregate characteristics can intensively interfere in concrete behavior especially when sulfides are presented in the aggregates. The lack of consensus to content limit value of these deleterious sulfur compounds in concrete structures for dams has motivated several investigations worldwide. Within this scenario, this work presents a methodology to evaluate the presence of pyrite and pyrrhotite in concretes produced with aggregates containing sulfides. For the study, rock samples from the Irapé hydroelectric power plant area in Minas Gerais (Brazil were used. This plant was built in a geological site where the rock presented sulfide levels of at least 3%. These rock samples were first ground and then used as aggregates in mortars, which were, during almost one year, subjected to three different exposed conditions: temperature of 23° ± 2°C and relative humidity of 95 to 100%; calcium hydroxide solution diluted in water kept at two different temperatures: room temperature and 50° C. The presence and amount of pyrrhotite were obtained from a leaching process of the material (aggregate or mortar in a solution of hydrochloric acid. This procedure allowed also the evaluation of the pyrite content. The results showed that the amount of pyrite has remained virtually constant over time in the three exposure situations. This finding indicates that sulfur limits in aggregates should be set according to the type of iron sulfide presented and not solely by the total amount of sulfur.

  2. Coal surface control for advanced physical fine coal cleaning technologies

    Energy Technology Data Exchange (ETDEWEB)

    Morsi, B.I.; Chiang, S.H.; Sharkey, A.; Blachere, J.; Klinzing, G.; Araujo, G.; Cheng, Y.S.; Gray, R.; Streeter, R.; Bi, H.; Campbell, P.; Chiarlli, P.; Ciocco, M.; Hittle, L.; Kim, S.; Kim, Y.; Perez, L.; Venkatadri, R.

    1992-01-01

    This final report presents the research work carried out on the Coal Surface Control for Advanced Physical Fine Coal Cleaning Technologies project, sponsored by the US Department of Energy, Pittsburgh Energy Technology Center (DOE/PETC). The project was to support the engineering development of the selective agglomeration technology in order to reduce the sulfur content of US coals for controlling SO[sub 2] emissions (i.e., acid rain precursors). The overall effort was a part of the DOE/PETCs Acid Rain Control Initiative (ARCI). The overall objective of the project is to develop techniques for coal surface control prior to the advanced physical fine coal cleaning process of selective agglomeration in order to achieve 85% pyrite sulfur rejection at an energy recovery greater than 85% based on run-of-mine coal. The surface control is meant to encompass surface modification during grinding and laboratory beneficiation testing. The project includes the following tasks: Project planning; methods for analysis of samples; development of standard beneficiation test; grinding studies; modification of particle surface; and exploratory R D and support. The coal samples used in this project include three base coals, Upper Freeport - Indiana County, PA, Pittsburgh NO. 8 - Belmont County, OH, and Illinois No. 6 - Randolph County, IL, and three additional coals, Upper Freeport - Grant County- WV, Kentucky No. 9 Hopkins County, KY, and Wyodak - Campbell County, WY. A total of 149 drums of coal were received.

  3. The Adsorption of Cu Species onto Pyrite Surface and Its Effect on Pyrite Flotation

    Directory of Open Access Journals (Sweden)

    Bo Yang

    2016-01-01

    Full Text Available The adsorption of Cu species onto pyrite surface and its effect on flotation were investigated by using microflotation tests, first-principle calculations, and XPS surface analysis. The results indicated that the flotation of pyrite appears to be activated with CuSO4 only at alkaline pH, while being depressed at acidic and neutral pH. The adsorption of copper ions on pyrite surface was pH-dependent, and the adsorption magnitude of copper ions at alkaline pH is higher than that at acidic and neutral pH due to a strong interaction between O atom in Cu(OH2 and surface Fe atom except for the interaction between Cu atom and surface S atom. At acidic and neutral pH, there is only an interaction between Cu atom and surface S atom. The adsorption was relatively weak, and more copper ions in solution precipitated the collector and depressed the flotation of pyrite. XPS analysis confirmed that more copper ionic species (Cu(I and Cu(II are adsorbed on the pyrite surface at alkaline pH than that at acidic and neutral pH.

  4. Macromolecule simulation and CH{sub 4} adsorption mechanism of coal vitrinite

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Song, E-mail: songyu10094488@126.com [School of Resources and Earth Science, China University of Mining & Technology, Xuzhou 221116 (China); Key Laboratory of Coal bed Methane Resource & Reservoir Formation Process, Ministry of Education, Xuzhou 221008 (China); Yan-ming, Zhu; Wu, Li [School of Resources and Earth Science, China University of Mining & Technology, Xuzhou 221116 (China); Key Laboratory of Coal bed Methane Resource & Reservoir Formation Process, Ministry of Education, Xuzhou 221008 (China)

    2017-02-28

    Highlights: • Molecular model of single maceral vitrinite was obtained by {sup 13}C NMR, FT IR and HRTEM. • An optimal configuration was obtained through calculation of MM and MD. • The adsorption parameters for methane and vitrinite were determined with DFT and GCMC. - Abstract: The microscopic mechanism of interactions between CH{sub 4} and coal macromolecules is of significant practical and theoretical importance in CBM development and methane storage. Under periodic boundary conditions, the optimal energy configuration of coal vitrinite, which has a higher torsion degree and tighter arrangement, can be determined by the calculation of molecular mechanics (MM) and molecular dynamics (MD), and annealing kinetics simulation based on ultimate analysis, {sup 13}C NMR, FT IR and HRTEM. Macromolecular stabilization is primarily due to the van der Waals energy and covalent bond energy, mainly consisting of bond torsion energy and bond angle energy. Using the optimal configuration as the adsorbent, GCMC simulation of vitrinite adsorption of CH{sub 4} is conducted. A saturated state is reached after absorbing 17 CH{sub 4}s per coal vitrinite molecule. CH{sub 4} is preferentially adsorbed on the edge, and inclined to gathering around the branched chains of the inner vitrinite sites. Finally, the adsorption parameters are calculated through first principle DFT. The adsorbability order is as follows: aromatic structure> heteroatom rings > oxygen functional groups. The adsorption energy order is as follows: Top < Bond < Center, Up < Down. The order of average RDF better reflects the adsorption ability and that of [-COOH] is lower than those of [−C=O] and [C−O−C]. CH{sub 4} distributed in the distance of 0.99–16 Å to functional groups in the type of monolayer adsorption and the average distance order manifest as [−C=O] (1.64 Å) < [C−O−C] (1.89 Å) < [−COOH] (3.78 Å) < [-CH{sub 3}] (4.11 Å) according to the average RDF curves. CH{sub 4} enriches

  5. Regional-scale geomechanical impact assessment of underground coal gasification by coupled 3D thermo-mechanical modeling

    Science.gov (United States)

    Otto, Christopher; Kempka, Thomas; Kapusta, Krzysztof; Stańczyk, Krzysztof

    2016-04-01

    Underground coal gasification (UCG) has the potential to increase the world-wide coal reserves by utilization of coal deposits not mineable by conventional methods. The UCG process involves combusting coal in situ to produce a high-calorific synthesis gas, which can be applied for electricity generation or chemical feedstock production. Apart from its high economic potentials, UCG may induce site-specific environmental impacts such as fault reactivation, induced seismicity and ground subsidence, potentially inducing groundwater pollution. Changes overburden hydraulic conductivity resulting from thermo-mechanical effects may introduce migration pathways for UCG contaminants. Due to the financial efforts associated with UCG field trials, numerical modeling has been an important methodology to study coupled processes considering UCG performance. Almost all previous UCG studies applied 1D or 2D models for that purpose, that do not allow to predict the performance of a commercial-scale UCG operation. Considering our previous findings, demonstrating that far-field models can be run at a higher computational efficiency by using temperature-independent thermo-mechanical parameters, representative coupled simulations based on complex 3D regional-scale models were employed in the present study. For that purpose, a coupled thermo-mechanical 3D model has been developed to investigate the environmental impacts of UCG based on a regional-scale of the Polish Wieczorek mine located in the Upper Silesian Coal Basin. The model size is 10 km × 10 km × 5 km with ten dipping lithological layers, a double fault and 25 UCG reactors. Six different numerical simulation scenarios were investigated, considering the transpressive stress regime present in that part of the Upper Silesian Coal Basin. Our simulation results demonstrate that the minimum distance between the UCG reactors is about the six-fold of the coal seam thickness to avoid hydraulic communication between the single UCG

  6. Process analysis and mechanism of multi-stage hydropyrolysis of coal

    Energy Technology Data Exchange (ETDEWEB)

    Li, W.; Wang, N.; Li, B.Q. [Chinese Academy of Science, Taiyuan (China). Inst. of Coal Chemistry, State Key Laboratory of Coal Conversion

    2002-07-01

    The mechanism of multi-stage hydropyrolysis of coal was probed through detailed analysis of products of hydropyrolysis with different holding methods. The results showed that the holding method significantly affects the product distributions, thus making an apparent difference in hydrogen utilization efficiency. The holding temperature should be about 350-500{degree}C during which more free radicals are produced rapidly. Pore-riched structures are formed at the holding stage at 350{degree}C due to the evolution of large amount of volatiles, which is favorable to the subsequent hydrogenation reaction. The holding at a low temperature favors the reaction of hydrogen with oxygen-containing groups, leading to the formation of phenol and avoiding the formation of water at a high temperature. The cleavage of chemical bonds in the char is mainly dependent-on the pyrolysis temperature. The effect of holding stage is to change the distribution and components of products via stabilizing the free radicals and hydrogenating the heavier products.

  7. 57Fe NGR studies on three-stage hydroliquefaction of coals

    International Nuclear Information System (INIS)

    Jamond, M.; Bacaud, R.; Bussiere, P.; Charcosset, H.; Nickel-Pepin-Donat, B.

    1990-01-01

    Iron Moessbauer spectroscopy has been performed on liquefaction residues of two different French coals. In a three-stage liquefaction of high volatile bituminous coal (Freyming), without an added catalyst, the coal pyrite is not entirely converted into pyrrhotites, whereas in the presence of an added catalyst, coal pyrite is totally transformed into more dispersed pyrrhotites than those from the sample without an added catalyst; furthermore, the whole added catalyst precursor is reduced into pyrrhotites. In the case of liquefaction of subbituminous coal (Gardanne), full conversion of coal pyrite into pyrrhotites (even without an added catalyst) occurs. In addition, in the presence of the added catalyst, besides pyrrhotites, FeS is evidenced. When molybdenum-iron oxide is added as a catalyst precursor, no mixed Fe-Mo phase is detected. (orig.)

  8. Determination of the Content of Heavy Metals in Pyrite Contaminated Soil and Plants

    Directory of Open Access Journals (Sweden)

    Miroslava Marić

    2008-09-01

    Full Text Available Determination of a pyrite contaminated soil texture, content of heavy metals in the soil and soil pH, was the aim in the investigation. Acidification of damaged soil was corrected by calcium carbonate. Mineral nutrients and organic matter (NPK, dung, earthworm cast, straw and coal dust were added to damaged soil. Afterwards, the soil was used for oat production. Determination of total heavy metal contents (Cu, Pb, Zn, Fe in soil was performed by atomic absorption spectrofotometry. Plant material (stems, seeds was analysed, too. Total concentration of the heavy metals in the plant material were greater than in crop obtained in unaffected soil.

  9. A strategic approach to selecting policy mechanisms for addressing coal mine methane emissions: A case study on Kazakhstan

    Energy Technology Data Exchange (ETDEWEB)

    Roshchanka, Volha; Evans, Meredydd; Ruiz, Felicia; Kholod, Nazar

    2017-12-01

    Coal production globally is projected to grow in the foreseeable future. Countries with heavy reliance on coal could reduce methane and other emissions through the capture and utilization of coal mine methane (CMM) in the short and medium term, while they pursue structural and long-term economic changes. Several countries have successfully implemented policies to promote CMM capture and utilization; however, some countries still struggle to implement projects. This paper outlines key factors to consider in adapting policies for CMM mitigation. The authors propose an approach for selecting adequate mechanisms for stimulating CMM mitigation that involves reviewing global best practices and categorizing them functionally either as mechanisms needed to improve the underlying conditions or as CMM-specific policies. It is important to understand local policy frameworks and to consider whether it is more feasible to improve underlying policy conditions or to provide targeted incentives as an interim measure. Using Kazakhstan as a case study, the authors demonstrate how policymakers could assess the overall policy framework to find the most promising options to facilitate CMM projects. Kazakhstan’s emissions from underground coal mines have been increasing both in total and per tonne of coal production, while overall production has been declining. CMM mitigation presents an opportunity for the country to reduce its greenhouse gas emissions in the near and medium term, while the government pursues sustainable development goals. Analysis shows that policymakers in Kazakhstan can leverage existing policies to stimulate utilization by extending feed-in tariffs to cover CMM and by developing working methodologies for companies to obtain emission reduction credits from CMM projects.

  10. Coal background paper. Coal demand

    International Nuclear Information System (INIS)

    1997-01-01

    Statistical data are presented on coal demands in IEA and OECD member countries and in other countries. Coal coaking and coaking coal consumption data are tabulated, and IEA secretariat's coal demand projections are summarized. Coal supply and production data by countries are given. Finally, coal trade data are presented, broken down for hard coal, steam coal, coking coal (imports and export). (R.P.)

  11. Mechanism of obtaining carbon monoxide and hydrogen during brown coal radiolysis. [Gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Rustamov, V R; Kurbanov, M A; Dzantiev, B T; Kerimov, V K; Musaeva, P F

    1982-05-01

    This article analyzes effects of gamma radiation on the yield of products of coal gasification: hydrogen and carbon monoxide. Samples of brown coal from the Kansk-Achins basin were treated by gamma radiation with cobalt 60 radiation source. Analyses show that accumulation of hydrogen and carbon monoxide in brown coal under influence of gamma radiation is characterized by a constant rate. Yields of carbon monoxide and hydrogen amount to 0.16 molecule/100 electro volt and 0.21 molecule/electro volt respectively. Reducing radiation dose from 2.5 to 0.7 millirad/h reduces yields of hydrogen and carbon monoxide. Increasing temperature of vacuum brown coal pyrolysis from 200 to 600 C causes decrease of hydrogen yield. Hydrogen yield decrease during temperature increase is caused by a high content of aromatic nuclei in the samples used in the radiolysis. (5 refs.)

  12. Biochemical Removal of HAP Precursors From Coal

    International Nuclear Information System (INIS)

    Olson, G.; Tucker, L.; Richards, J.

    1997-07-01

    This project addresses DOE's interest in advanced concepts for controlling emissions of air toxics from coal-fired utility boilers. We are determining the feasibility of developing a biochemical process for the precombustion removal of substantial percentages of 13 inorganic hazardous air pollutant (HAP) precursors from coal. These HAP precursors are Sb, As, Be, Cd, Cr, Cl, Co, F, Pb, Hg, Mn, Ni, and Se. Although rapid physical coal cleaning is done routinely in preparation plants, biochemical processes for removal of HAP precursors from coal potentially offer advantages of deeper cleaning, more specificity, and less coal loss. Compared to chemical processes for coal cleaning, biochemical processes potentially offer lower costs and milder process conditions. Pyrite oxidizing bacteria, most notably Thiobacillusferrooxidans, are being evaluated in this project for their ability to remove HAP precursors from U.S. coals

  13. Biochemical Removal of HAP Precursors From Coal

    Energy Technology Data Exchange (ETDEWEB)

    Olson, G.; Tucker, L.; Richards, J.

    1997-07-01

    This project addresses DOE`s interest in advanced concepts for controlling emissions of air toxics from coal-fired utility boilers. We are determining the feasibility of developing a biochemical process for the precombustion removal of substantial percentages of 13 inorganic hazardous air pollutant (HAP) precursors from coal. These HAP precursors are Sb, As, Be, Cd, Cr, Cl, Co, F, Pb, Hg, Mn, Ni, and Se. Although rapid physical coal cleaning is done routinely in preparation plants, biochemical processes for removal of HAP precursors from coal potentially offer advantages of deeper cleaning, more specificity, and less coal loss. Compared to chemical processes for coal cleaning, biochemical processes potentially offer lower costs and milder process conditions. Pyrite oxidizing bacteria, most notably Thiobacillusferrooxidans, are being evaluated in this project for their ability to remove HAP precursors from U.S. coals.

  14. Thermodynamic comparison and efficiency enhancement mechanism of coal to alternative fuel systems

    International Nuclear Information System (INIS)

    Ji, Xiaozhou; Li, Sheng; Gao, Lin; Jin, Hongguang

    2016-01-01

    Highlights: • Energy and exergy analysis are presented to three coal-to-alternative-fuels systems. • Internal reasons for performance differences for different systems are disclosed. • The temperature and heat release of synthesis reactions are key to plant efficiency. • The distillation unit and purge gas recovery are important to efficiency enhancement. - Abstract: Coal to alternative fuels is an important path to enforce energy security and to provide clean energy. In this paper, we use exergy analysis and energy utilization diagram (EUD) methods to disclose the internal reasons for performance differences in typical coal to alternative fuel processes. ASPEN plus software is used to simulate the coal-based energy systems, and the simulation results are verified with engineering data. Results show that coal to substitute natural gas (SNG) process has a higher exergy efficiency of 56.56%, while the exergy efficiency of traditional coal to methanol process is 48.65%. It is indicated that three key factors impact the performance enhancement of coal to alternative fuel process: (1) whether the fuel is distillated, (2) the synthesis temperature and the amount of heat release from reactions, and (3) whether the chemical purge gases from synthesis and distillation units are recovered. Distillation unit is not recommended and synthesis at high temperature and with large heat release is preferable for coal to alternative fuel systems. Gasification is identified as the main source of exergy destruction, and thereby how to decrease its destruction is the key direction of plant efficiency improvement in the future. Also, decreasing the power consumption in air separation unit by seeking for advanced technologies, i.e. membrane, or using another kind of oxidant is another direction to improve plant performance.

  15. Microbiological desulfurization and conversion of coal

    International Nuclear Information System (INIS)

    Quigley, D.R.; Stoner, D.L.; Dugan, P.R.

    1991-01-01

    Bio processing of coal is a young and emerging technology. Until the early 1980's it consisted primarily of coal depyritization using Thiobacillus ferro oxidans to either oxidize pyritic sulfur or to alter particle wettability or floatation properties by binding to exposed pyrite inclusions. Since then, other major avenues of research have been pursued. One of these is the microbiologically mediated liquefaction of coal. Initial work indicated that microorganisms were able to transform low rank coal into a black liquid that was later identified as water solubilized by alkaline substances produced by the microbes and could be enhanced by the removal of multi valent cations from coal. Current work at the INEL involves of the identification and characterization of microorganisms that are able to alter the structure of polymeric desulfurization of coal. This work initially focused on the ability of microorganisms to oxidatively remove organic sulfur from model compounds that were representative of those sulfur containing moieties identified as being in coals (e.g., dibenzo thiophene). The work also focused on those organisms that were could remove the organic sulfur without degrading the carbon structure. While some organisms that are able to perform such these reactions will effectively remove organo sulfur from coal. These concerns stem from steric hindrance considerations and the thermodynamically unfavourable nature of reaction. Current work at the INEL involves the isolation and biochemical characterization of microorganisms that are able to desulfurize and solubilized coals that have high organic sulfur contents. (author)

  16. Mechanism of Wandoan coal liquefaction by the use of tritium and 14C tracer method

    International Nuclear Information System (INIS)

    Kabe, Toshiaki; Nitoh, Osamu; Kawakami, Akira; Marumoto, Motoi; Nakagawa, Kouhei

    1986-01-01

    In order to make the behavior of hydrogen donor solvent clear, Wandoan coal was liquefied in tritium labeled tetralin solvent contained a small amount of 14 C labeled naphthalene, under initial H 2 pressure : 5.9 MPa, reaction temperature range : 400-440 deg C and with or without Ni-Mo-Al 2 O 3 catalyst. The concentration of 14 C in tetralin indicated that the hydrogenation of naphthalene to tetralin occurred. From tritium and hydrogen distributions in coal products, solvents and molecular hydrogen, the amounts of hydrogen which transferred by hydrogen addition and exchange reactions were estimated, and the effects of the catalyst and reaction temperature were examined. Without catalyst, the coal liquefaction proceeded mainly by the hydrogen addition from hydrogen donor solvent to coal and the hydrogen addition from molecular hydrogen to coal products hardly occurred. The catalyst was effective in the hydrocracking of preasphaltenes, but did not promote the hydrocracking of oil. Furthermore, the catalyst promoted the hydrogen addition from molecular hydrogen to coal products and solvents, and activated the hydrogen exchange between molecular hydrogen and solvents, but the hydrogen exchanges did not reach to equilibrium under the condition of 440 deg C. (author)

  17. Disposing of coal combustion residues in inactive surface mines: Effects on water quality

    International Nuclear Information System (INIS)

    Kim, A.G.; Ackman, T.E.

    1994-01-01

    The disposal of coal combustion residues (CCR) in surface and underground coal mines can provide a stable, low-maintenance alternative to landfills, benefiting the mining and electric power industries. The material may be able to improve water quality at acid generating abandoned or reclaimed coal mine sites. Most combustion residues are alkaline, and their addition to the subsurface environment could raise the pH, limiting the propagation of pyrite oxidizing bacteria and reducing the rate of acid generation. Many of these CCR are also pozzolanic, capable of forming cementitious grouts. Grouts injected into the buried spoil may decrease its permeability and porosity, diverting water away from the pyritic material. Both mechanisms, alkaline addition and water diversion, are capable of reducing the amount of acid produced at the disposal site. The US Bureau of Mines is cooperating in a test of subsurface injection of CCR into a reclaimed surface mine. Initially, a mixture of fly ash, lime, and acid mine drainage (AMD) sludge was injected. Lime was the source of calcium for the formation of the pozzolanic grout. Changes in water quality parameters (pH, acidity, anions, and trace metals) in water samples from wells and seeps indicate a small but significant improvement after CCR injection. Changes in the concentration of heavy metals in the water flowing across the site were apparently influenced by the presence of flyash

  18. Solvent extraction of elemental sulfur from coal and a determination of its source using stable sulfur isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Hackley, K.C.; Buchanan, D.H.; Coombs, K.; Chaven, C.; Kruse, C.W. (Eastern Illinois University, Charleston, IL (USA). Chemistry Dept.)

    1990-01-01

    Hot tetrachloroethene (perchloroethylen PCE) extracts significant amounts of elemental sulfur (S{sup o}) from weathered coals but not from pristine coals. The objective of this study was to determine whether S{sup o} extracted by PCE is an oxidation product of pyrite or whether it originates in some way from unstable, organically-bound sulfur. The isotopic composition of the PCE-extracted S{sup o} was compared to the isotopic compositions of the pyritic and the organic sulfur in a coal. The S{sup o} was shown to have an isotopic signature similar to the pyritic sulfur. Additionally, the isotopic differences observed between the pyritic, S{sup o} and sulfatic sulfur were consistent with bacterial mediated oxidation of sulfide sulfur (pyrite) as the source of both the sulfatic and elemental sulfur. 21 refs., 2 tabs.

  19. Solvent extraction of elemental sulfur from coal and a determination of its source using stable sulfur isotopes

    Science.gov (United States)

    Hackley, Keith C.; Buchanan, D.H.; Coombs, K.; Chaven, C.; Kruse, C.W.

    1990-01-01

    Hot tetrachloroethene (perchloroethylene, PCE) extracts significant amounts of elemental sulfur (So) from weathered coals but not from pristine coals. The objective of this study was to determine whether So extracted by PCE is an oxidation product of pyrite or whether it originates in some way from unstable, organically-bound sulfur. The isotopic composition of the PCE-extracted So was compared to the isotopic compositions of the pyritic and the organic sulfur in a coal. The So was shown to have an isotopic signature similar to the pyritic sulfur. Additionally, the isotopic differences observed between the pyritic, So and sulfatic sulfur were consistent with bacterial mediated oxidation of sulfide sulfur (pyrite) as the source of both the sulfatic and elemental sulfur. ?? 1990.

  20. Numerical simulation of head top coal's stability control of fully mechanized longwall mining with sublevel caving face in large dip seam

    Energy Technology Data Exchange (ETDEWEB)

    Li, W.; Wan, Z.; Jiang, F.; Jia, P. [Beijing Science and Technology University, Beijing (China)

    2008-07-01

    Stability control of the head face's top-coal is one of the key techniques of realising high production and high efficiency in coal mining in fully mechanized top-coal caving face. The characteristics of the stress in the overlying strata of the fully mechanized top-coal caving face and the top coal were analysed using FLAC{sup 3D}. The results show that the tip-to-face top-coal generates a large deformation while it is in the stress-relaxed area. The top-coal in the front of the wall appears to be the failure area for the effect of the abutment pressure that spreads over the coal seam. The surrounding rock of the upper face end is the key part strengthened the control of the rib spalling. The first and frequent appearing phenomenon of losing stability of the powered supports is that the back base of the hydraulic power supports in the top of the face slips. Increasing the quality of support and so on can maintain the stability of surrounding rock. 4 refs., 7 figs., 1 tab.

  1. Correlation of Surface Adsorption and Oxidation with a Floatability Difference of Galena and Pyrite in High-Alkaline Lime Systems.

    Science.gov (United States)

    Niu, Xiaopeng; Ruan, Renman; Xia, Liuyin; Li, Li; Sun, Heyun; Jia, Yan; Tan, Qiaoyi

    2018-02-27

    When it comes to Pb-Zn ores with high amounts of pyrite, the major problem encountered is the low separation efficiency between galena and pyrite. By virtue of high dosage of lime and collector sodium diethyl dithiocarbamate (DDTC), pyrite and zinc minerals are depressed, allowing the galena to be floated. However, there have been significant conflicting reports on the flotation behavior of galena at high pH. In this context, correlation of the surface adsorption and oxidation with the floatability difference of galena and pyrite in high-alkaline lime systems would be a key issue for process optimization. Captive bubble contact angle measurements were performed on freshly polished mineral surfaces in situ exposed to lime solutions of varying pH as a function of immersion time. Furthermore, single mineral microflotation tests were conducted. Both tests indicated that the degree of hydrophobicity on the surfaces of galena and pyrite increased in the presence of DDTC at natural or mild pulp pH. While in a saturated lime solution, at pH 12.5, DDTC only worked for galena, but not for pyrite. Surface chemistry analysis by time-of-flight secondary ion mass spectrometry (Tof-SIMS) confirmed the preference of DDTC on the galena surface at pH 12.5, which contributed to a merit recovery. Further important evidence through measurements of Tof-SIMS, ion chromatography, and high-performance liquid chromatography indicated that in high-alkaline lime systems, the merit floatability of galena could exclude the insignificant contribution of elemental sulfur (S 8 ) and was dominantly attributed by the strong adsorption of DDTC. In contrast, the poor flotation response of pyrite at high pH was due to the prevailing adsorption of CaOH + species. This study provides an important surface chemistry evidence for a better understanding of the mechanism on the better selectivity in the galena-pyrite separation adopting high-alkaline lime systems.

  2. Hydration mechanism and leaching behavior of bauxite-calcination-method red mud-coal gangue based cementitious materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Na; Li, Hongxu [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Laboratory of Rare and Precious Metals Green Recycling and Extraction, University of Science and Technology Beijing, Beijing 100083 (China); Liu, Xiaoming, E-mail: liuxm@ustb.edu.cn [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Laboratory of Rare and Precious Metals Green Recycling and Extraction, University of Science and Technology Beijing, Beijing 100083 (China)

    2016-08-15

    Highlights: • Nanocrystalline regions in size of ∼5 nm were found in the amorphous C-A-S-H gel. • A hydration model was proposed to clarify the hydration mechanism. • The developed cementitious materials are environmentally acceptable. - Abstract: A deep investigation on the hydration mechanism of bauxite-calcination-method red mud-coal gangue based cementitious materials was conducted from viewpoints of hydration products and hydration heat analysis. As a main hydration product, the microstructure of C-A-S-H gel was observed using high resolution transmission electron microscopy. It was found that the C-A-S-H gel is composed of amorphous regions and nanocrystalline regions. Most of regions in the C-A-S-H gel are amorphous with continuous distribution, and the nanocrystalline regions on scale of ∼5 nm are dispersed irregularly within the amorphous regions. The hydration heat of red mud-coal gangue based cementitious materials is much lower than that of the ordinary Portland cement. A hydration model was proposed for this kind of cementitious materials, and the hydration process mainly consists of four stages which are dissolution of materials, formation of C-A-S-H gels and ettringite, cementation of hydration products, and polycondensation of C-A-S-H gels. There are no strict boundaries among these four basic stages, and they proceed crossing each other. Moreover, the leaching toxicity tests were also performed to prove that the developed red mud-coal gangue based cementitious materials are environmentally acceptable.

  3. Rent-seeking mechanism for safety supervision in the Chinese coal industry based on a tripartite game model

    International Nuclear Information System (INIS)

    Chen, Hong; Feng, Qun; Cao, Jing

    2014-01-01

    There are extensive governmental rent-seeking activities in safety supervision of the Chinese coal industry. The rents come from industry safety barriers, low resource taxes, and privilege policies for coalmining enterprises. The rent-seeking mechanism was analyzed using a model comprising dynamic games with incomplete information. The equilibrium results indicate that the probability of national supervision is influenced by penalties and bribery: there is negative correlation with penalties and positive correlation with bribery. The rent-seeking probability of a governmental safety supervision department is influenced by several factors, and positively correlates with the cost of national supervision. The probability of bribery of coalmining enterprises is influenced by several factors, and positively correlates with wages of governmental departments and a reasonable rent-seeking range. Reversed rent-seeking reduces the probability of bribery, but it's not worth recommending. Some recommendations are proposed. - Highlights: • We analyze rent-seeking mechanism for safety supervision in the coal industry. • A dynamic game with incomplete information for Chinese coal industry is built. • Reversed rent-seeking is proposed as a new rent-seeking form. • We analyze the selection probability of the three participants. • We give some policies about how to enhance safety supervision

  4. Hydration mechanism and leaching behavior of bauxite-calcination-method red mud-coal gangue based cementitious materials

    International Nuclear Information System (INIS)

    Zhang, Na; Li, Hongxu; Liu, Xiaoming

    2016-01-01

    Highlights: • Nanocrystalline regions in size of ∼5 nm were found in the amorphous C-A-S-H gel. • A hydration model was proposed to clarify the hydration mechanism. • The developed cementitious materials are environmentally acceptable. - Abstract: A deep investigation on the hydration mechanism of bauxite-calcination-method red mud-coal gangue based cementitious materials was conducted from viewpoints of hydration products and hydration heat analysis. As a main hydration product, the microstructure of C-A-S-H gel was observed using high resolution transmission electron microscopy. It was found that the C-A-S-H gel is composed of amorphous regions and nanocrystalline regions. Most of regions in the C-A-S-H gel are amorphous with continuous distribution, and the nanocrystalline regions on scale of ∼5 nm are dispersed irregularly within the amorphous regions. The hydration heat of red mud-coal gangue based cementitious materials is much lower than that of the ordinary Portland cement. A hydration model was proposed for this kind of cementitious materials, and the hydration process mainly consists of four stages which are dissolution of materials, formation of C-A-S-H gels and ettringite, cementation of hydration products, and polycondensation of C-A-S-H gels. There are no strict boundaries among these four basic stages, and they proceed crossing each other. Moreover, the leaching toxicity tests were also performed to prove that the developed red mud-coal gangue based cementitious materials are environmentally acceptable.

  5. Bacterial leaching of pyritic gold ores

    Energy Technology Data Exchange (ETDEWEB)

    Gagliardi, F.M.; Cashion, J.D.; Brown, L.J. [Monash Univ., Clayton, VIC (Australia). Dept. of Physics; Jay, W.H. [Monash Univ., Clayton, VIC (Australia). Chemical Engineering Department

    1996-12-31

    The bacterial oxidation process is well known in nature but has only recently come under investigation as a viable and relatively clean method of gold recovery from ores. However there is currently little information about the process at an atomic scale. It is known that the bacterial attack progresses preferentially along grain boundaries which is precisely where the gold has been deposited from aqueous infiltration. Samples have been obtained from the Wiluna mine in Western Australia consisting of the original ore, 2 pre-treatments, and from six successive bacterial reactors. {sup 57}Fe Moessbauer spectra taken at room temperature show only two quadrupole split doublets which can be ascribed to pyrite, FeS{sub 2}, and arsenopyrite, FeAsS. However, the presence of any superparamagnetic oxide or oxyhydroxide species would be expected to give a spectrum very similar to that of pyrite and would be undetectable in small quantities. At a temperature of 5K, a broad magnetically split sextet is observable with a mean hyperfine field of approximately 50T. This field is characteristic of magnetically ordered ferric iron surrounded by an octahedron of oxygens. The intensity and characteristics of this subspectrum alters through the series and interpretations will be given on the oxidation products of the bacterial leaching

  6. Bacterial leaching of pyritic gold ores

    International Nuclear Information System (INIS)

    Gagliardi, F.M.; Cashion, J.D.; Brown, L.J.; Jay, W.H.

    1996-01-01

    The bacterial oxidation process is well known in nature but has only recently come under investigation as a viable and relatively clean method of gold recovery from ores. However there is currently little information about the process at an atomic scale. It is known that the bacterial attack progresses preferentially along grain boundaries which is precisely where the gold has been deposited from aqueous infiltration. Samples have been obtained from the Wiluna mine in Western Australia consisting of the original ore, 2 pre-treatments, and from six successive bacterial reactors. 57 Fe Moessbauer spectra taken at room temperature show only two quadrupole split doublets which can be ascribed to pyrite, FeS 2 , and arsenopyrite, FeAsS. However, the presence of any superparamagnetic oxide or oxyhydroxide species would be expected to give a spectrum very similar to that of pyrite and would be undetectable in small quantities. At a temperature of 5K, a broad magnetically split sextet is observable with a mean hyperfine field of approximately 50T. This field is characteristic of magnetically ordered ferric iron surrounded by an octahedron of oxygens. The intensity and characteristics of this subspectrum alters through the series and interpretations will be given on the oxidation products of the bacterial leaching

  7. Thin film preparation of semiconducting iron pyrite

    Science.gov (United States)

    Smestad, Greg P.; Ennaoui, Ahmed; Fiechter, Sebastian; Hofmann, Wolfgang; Tributsch, Helmut; Kautek, Wolfgang

    1990-08-01

    Pyrite (Fe52) has been investigated as a promising new absorber material for thin film solar cell applications because of its high optical absorption coefficient of 1OL cm1, and its bandgap of 0.9 to 1.0 eV. Thin layers have been prepared by Metal Organic Chemical Vapor Deposition, MOCVD, Chemical Spray Pyrolysis, CSP, Chemical Vapor Transport, CVT, and Sulfurization of Iron Oxide films, 510. It is postulated that for the material FeS2, if x is not zero, a high point defect concentration results from replacing 2 dipoles by single S atoms. This causes the observed photovoltages and solar conversion efficiencies to be lower than expected. Using the Fe-O-S ternary phase diagram and the related activity plots, a thermodynamic understanding is formulated for the resulting composition of each of these types of films. It is found that by operating in the oxide portion of the phase diagram, the resulting oxidation state favors pyrite formation over FeS. By proper orientation of the grains relative to the film surface, and by control of pinholes and stoichiometry, an efficient thin film photovolatic solar cell material could be achieved.

  8. Coal chemistry and technology. Komur Kimyasi ve Teknolojisi

    Energy Technology Data Exchange (ETDEWEB)

    Kural, O [ed.

    1988-01-01

    The 18 chapters cover the following topics: mining in Turkey; formation, petrography and classification of coal; chemical and physical properties of coal; mechanical properties of coal; spontaneous combustion of coal and the methods of prevention; sampling of coal; coal preparation and plants; desulfurization of coal; bituminous coal and its consumption; lignite and its consumption; world coal trade and transportation; other important carbon fuels; briquetting of coal; carbonization and coking formed coke; liquefaction of coal; gasification of coal; underground gasification of coal; and combustion models, fluidized-bed combustion, furnaces. An English-Turkish coal dictionary is included. 641 refs., 244 figs., 108 tabs.

  9. Kinetics of coal combustion: Part 3, Mechanisms and kinetics of char combustion

    Energy Technology Data Exchange (ETDEWEB)

    Gavalas, G. R.; Flagan, R. C. [California Inst. of Tech., Pasadena, CA (USA)

    1988-09-01

    This report summarizes a three-year research program aimed at developing this level of understanding of char combustion through a combination of detailed analysis of chars as produced during devolatilization and as they evolve during oxidation, and theoretical studies of the porous microstructures and of pore diffusion and reaction within the coal particles. A small number of coals have been studied in detail, namely a HVA bituminous (PSOC 1451), a sub-bituminous (PSOC 1488), and a lignite (PSOC 1443). Chars have been generated from size-classified samples of these coals by pyrolysis in an inert atmosphere in a drop tube furnace. The chars were then characterized both chemically and physically. Subsequent oxidation studies were performed on these chars. 42 refs., 54 figs., 4 tabs.

  10. An experimental study on the hazard assessment and mechanical properties of porous concrete utilizing coal bottom ash coarse aggregate in Korea.

    Science.gov (United States)

    Park, Seung Bum; Jang, Young Il; Lee, Jun; Lee, Byung Jae

    2009-07-15

    This study evaluates quality properties and toxicity of coal bottom ash coarse aggregate and analyzes mechanical properties of porous concrete depending on mixing rates of coal bottom ash. As a result, soundness and resistance to abrasion of coal bottom ash coarse aggregate were satisfied according to the standard of coarse aggregate for concrete. To satisfy the standard pertaining to chloride content, the coarse aggregates have to be washed more than twice. In regards to the result of leaching test for coal bottom ash coarse aggregate and porous concrete produced with these coarse aggregates, it was satisfied with the environment criteria. As the mixing rate of coal bottom ash increased, influence of void ratio and permeability coefficient was very little, but compressive and flexural strength decreased. When coal bottom ash was mixed over 40%, strength decreased sharply (compressive strength: by 11.7-27.1%, flexural strength: by maximum 26.4%). Also, as the mixing rate of coal bottom ash increased, it was confirmed that test specimens were destroyed by aggregate fracture more than binder fracture and interface fracture. To utilize coal bottom ash in large quantities, it is thought that an improvement method in regards to strength has to be discussed such as incorporation of reinforcing materials and improvement of aggregate hardness.

  11. Studies on the effect of coal particle size on biodepyritization of high sulfur coal in batch bioreactor

    Directory of Open Access Journals (Sweden)

    Singh Sradhanjali

    2015-03-01

    Full Text Available The moderate thermophilic mix culture bacteria were used to depyritize the Illinois coal of varying particle sizes (-100 μm, 100-200 μm, +200 μm. Mineral libration analysis showed the presence of pyrite along with other minerals in coal. Microbial depyritization of coal was carried out in stirred tank batch reactors in presence of an iron-free 9K medium. The results indicate that microbial depyritization of coal using moderate thermophiles is an efficient process. Moreover, particle size of coal is an important parameter which affects the efficiency of microbial depyritization process. At the end of the experiment, a maximum of 75% pyrite and 66% of pyritic sulphur were removed from the median particle size. The XRD analysis showed the absence of pyrite mineral in the treated coal sample. A good mass balance was also obtained with net loss of mass ranging from 5-9% showing the feasibility of the process for large scale applications.

  12. Investigating the formation of acid mine drainage of Toledo pyrite concentrate using column cells

    Science.gov (United States)

    Aguila, Diosa Marie

    2018-01-01

    Acid mine drainage (AMD) is an inevitable problem in mining and has adverse effects in water quality. Studying AMD formation will be valuable in controlling the composition of mine waters and in planning the rehabilitation method for a mine. In this research, kinetics of AMD formation of Toledo pyrite was studied using two column experiments. The mechanisms of AMD formation and the effects of various factors on pH drop were first studied. Another column test was done for validation and to study the role of Fe2+/Fe3+ ratio in the change of leachate pH. The first experiment revealed that time and particle size are the most significant factors. It was also observed that the sudden pH drop during the starting hours was due to cracks formed from beneficiation, and the formation of Fe(OH)3. The laddered behavior of pH thereafter was due to decrease in formation of Fe(OH)3, and the precipitates in pyrite surface that lowered the surface area available for pyrite oxidation. The results of the second experiment validated the laddered behavior of pH. It was also observed that particle size distribution and pyrite surface were affected by the change in pH. Fe2+/Fe3+ ratio of leachate generally decreased as pH dropped.

  13. Pyrite-coated granite cobbles at Lee Bay, Stewart Island

    International Nuclear Information System (INIS)

    Brathwaite, R.L.; Skinner, D.N.B.; Faure, K.; Edwards, E.

    2014-01-01

    On the west side of Lee Bay on the northeast coast of Stewart Island, ventifact cobbles of pyrite-coated granite occur on the beach near the high tide mark and appear to be derived from a sand-cemented gravel deposit that forms a low bank at the back of the beach. The pyrite coat (up to 1 mm thick) completely covers the granitic cobbles and is zoned, with an inner zone of fine-grained colloform pyrite and an outer framboidal zone. Framboidal pyrite is typically formed in anoxic sedimentary environments. Subrounded grains of hematite, ilmenite with hematite blebs, magnetite, feldspar, biotite, quartz and zircon are present in the outer framboidal zone, with some ilmenite and hematite grains being partially replaced by pyrite. The assemblage of ilmenite-hematite-magnetite-biotite-zircon is similar both in mineralogy and size range to that found in heavy mineral beach sands. Sulphur isotope values of the pyrite coat are consistent with formation of the pyrite by microbial sulphate reduction of seawater sulphate. The framboidal texture together with the presence of grains of beach sand in the pyrite coating indicate that it was deposited in a low-temperature sedimentary environment. (author)

  14. Catalytic mechanism of sodium compounds in black liquor during gasification of coal black liquor slurry

    International Nuclear Information System (INIS)

    Kuang Jianping; Zhou Junhu; Zhou Zhijun; Liu Jianzhong; Cen Kefa

    2008-01-01

    The coal black liquor slurry (CBLS) was composed of coal and black pulping liquor, which has plenty of sodium compounds, lignin and cellulose. The sodium compounds have a catalytic effect on the gasification process of coal black liquor slurry, while lignin and cellulose enhance the heat value. Alkali-catalyzed gasification experiments of CBLS and CWS (coal water slurry) are investigated on the thermobalance and fixed bed reactor. The residues of the gasification of CBLS and CWS are analyzed by XRD, SEM and FT-IR. It is found that many micro- and mesopores and zigzag faces exist in the surface of the CBLS coke, which play a key role in the catalytic gasification. Sodium can enhance the reaction potential, weaken the bond of C-O and improve the gasification reaction rate. XRD results show that sodium aluminum silicate and nepheline are the main crystal components of the CBLS and CWS. The C-O stretching vibration peak in the 1060 cm -1 band in the CBLS shifts to 995.65 cm -1 in the CBLS coke after partial gasification. This means that the energy of the C-O stretching vibration in the CBLS carbon matrix decreases, so the structure of the carbon matrix is more liable to react with an oxygen ion or hydroxide ion. The amplitude of the C-O stretching vibration peak is augmented step by step due to the ground-excited level jump of the C-O band

  15. Investigation on Mechanical Behaviour of Coal and Overburden Rock for UCG

    NARCIS (Netherlands)

    Shojai Kaveh, N.; Barnhoorn, A.; Wolf, K.H.A.A.

    2015-01-01

    In recent years, the coupled UCG-CCS process has been considered as another potential CCS option, which can offer integrated energy recovery from coal and storage of CO2. However, existing potential problems may counteract its potential benefits. To develop a generic UCG-CCS site characterisation

  16. Numerical Investigation of Influences of Drilling Arrangements on the Mechanical Behavior and Energy Evolution of Coal Models

    Directory of Open Access Journals (Sweden)

    Tong-bin Zhao

    2018-01-01

    Full Text Available Destress drilling method is one of the commonly used methods for mitigating rock bursts, especially in coal mining. To better understand the influences of drilling arrangements on the destress effect is beneficial for rock burst mitigation. This study first introduced the rock burst mitigation mechanism of the destress drilling method and then numerically investigated the influences of drilling arrangements on the mechanical properties of coal models through uniaxial compression tests. Based on the test results, the energy evolution (i.e., the energy dissipation and bursting energy indexes influenced by different drilling arrangements was analyzed. When the drilling diameter, the number of drilling holes in one row, or the number of drilling rows increases, the bearing capacity of specimens nonlinearly decreases, but the energy dissipation index increases. In addition, the drilling diameter or the number of drilling holes in one row affects the failure mode weakly, which is different from that of the number of drilling rows. Consequently, the bursting energy index decreases as increasing the drilling diameter or the number of drilling holes in one row, but as increasing the number of drilling rows, the variation law of bursting energy index is not obvious. At last, the influencing mechanism of drilling arrangement on the rock burst prevention mechanism of the destress drilling method was discussed and revealed.

  17. Enhancement of Biofilm Formation on Pyrite by Sulfobacillus thermosulfidooxidans

    Directory of Open Access Journals (Sweden)

    Qian Li

    2016-07-01

    Full Text Available Bioleaching is the mobilization of metal cations from insoluble ores by microorganisms. Biofilms can enhance this process. Since Sulfobacillus often appears in leaching heaps or reactors, this genus has aroused attention. In this study, biofilm formation and subsequent pyrite dissolution by the Gram-positive, moderately thermophilic acidophile Sulfobacillus thermosulfidooxidans were investigated. Five strategies, including adjusting initial pH, supplementing an extra energy source or ferric ions, as well as exchanging exhausted medium with fresh medium, were tested for enhancement of its biofilm formation. The results show that regularly exchanging exhausted medium leads to a continuous biofilm development on pyrite. By this way, multiply layered biofilms were observed on pyrite slices, while only monolayer biofilms were visible on pyrite grains. In addition, biofilms were proven to be responsible for pyrite leaching in the early stages.

  18. Selective separation of pyrite and chalcopyrite by biomodulation.

    Science.gov (United States)

    Chandraprabha, M N; Natarajan, K A; Modak, Jayant M

    2004-09-01

    Selective separation of pyrite from other associated ferrous sulphides at acidic and neutral pH has been a challenging problem. This paper discusses the utility of Acidithiobacillus ferrooxidans for the selective flotation of chalcopyrite from pyrite. Consequent to interaction with bacterial cells, pyrite remained depressed even in the presence of potassium isopropyl xanthate collector while chalcopyrite exhibited significant flotability. However, when the minerals were conditioned together, the selectivity achieved was poor due to the activation of pyrite surface by the copper ions in solution. The selectivity was improved when the sequence of conditioning with bacterial cells and collector was reversed, since the bacterial cells were able to depress collector interacted pyrite effectively, while having negligible effect on chalcopyrite. The observed behaviour is analysed and discussed in detail. The separation obtained was significant both at acidic and alkaline pH. This selectivity achieved was retained when the minerals were interacted with both bacterial cells and collector simultaneously.

  19. Mechanism and Prevention of a Chock Support Failure in the Longwall Top-Coal Caving Faces: A Case Study in Datong Coalfield, China

    Directory of Open Access Journals (Sweden)

    Zhu Li

    2018-01-01

    Full Text Available Longwall chock support failures seriously restrain the safety and high-efficiency of mining of extra thick coal seams, as well as causing a great waste of coal resources. During longwall top-coal caving (LTCC, the influential effect of the properties and the movement regulation of top-coal on strata behavior cannot be ignored, since the top-coal is the medium through which the load of the overlying strata is transferred to the chock supports. Taking Datong coalfield as an example, the mechanism of a chock support failure in the LTCC face was investigated. Research findings indicated that the hard top-coal and insufficient chock support capacity were primary reasons for chock support failure accidents. On account of the field-measured results, a new method to determine support capacity was proposed, which fully took the impact of the top-coal strength into consideration. The calculation revealed that the required support capacity had exceeded the existing production maximum, at about 22,000 KN. Since it was unrealistic to simply increase chock support capacity, other approaches, according to the theoretical analysis, were proposed, such as lowering the integrity and strength of the top-coal, and upgrading its crushing effect to weaken the support load effectively during the weighting period, which reduces the likelihood of chock support accidents occurring. Based on this, hydraulic fracturing for hard top-coal and optimization of the caving process (chock supports raised up and down repeatedly by manual operation before moving forward were presented. The proposed solutions were successfully applied in LTCC-west8101 for subsequent mining and achieved substantial benefits. The above research provides valuable references and ideas for the control of strata behavior to ensure safe and highly efficient mining in extremely thick and hard coal seams with the LTCC method.

  20. Evaluation of the effect of macerals on coal permeability in Tazareh and Parvadeh mines

    Directory of Open Access Journals (Sweden)

    Farhang Sereshki

    2016-08-01

    Full Text Available In recent decades, the subject of gas emission in underground coal mines in many countries is an important subject. Many factors affect in gas emissions in coal seams. Geological and physical structures of coal are affecting on gas emissions'. Also, composition and mineralization of coal, affect in coal permeability for different gases. In this study, the relationship between maceral composition and coal permeability in Tazareh and Parvadeh mines has been studied. Accordingly, a laboratory studies to investigate the relationship between coal composition and coal permeability was done. In coal samples, with MFORR equipment the permeability test was done. With microscopic analysis, the maceral contents of coal such as Inertinite and Vitrinite have been measured. Accordingly, many coal samples of Parvadeh and Tazareh coal mines have the pyrite as the dominant mineral matter. Parvadeh coal samples has the average percentage of Vitrinite equal 81.34% and 10.52% Inertinite. Also, in the Tazareh coal samples in Eastern Alborz coal mines, the average percentage of Vitrinite is 69.31% and inertinite is 22.47%. The average percentage of Pyrite content in Parvadeh coal samples in Tabas coal mines is 2.38% and in the Tazareh coal samples in Eastern Alborz coal mines is 2.62%.  The permeability test results have been shown, which, with increase of Inertinite contents, the permeability of coal is increasing. Also, test results have been shown, there was a reduction in the coal permeability with increasing of mineral contents and carbonate contents of the coal. So, the coal permeability in Tabas coal samples is more than Eastern Alborz coal samples.

  1. Role of non-ferrous coal minerals and by-product metallic wastes in coal liquefaction. Technical progress report, September 1, 1980-November 30, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Garg, D.; Givens, E.N.; Schweighardt, F.K.; Curtis, C.W.; Guin, J.A.; Shridharani, K.; Huang, W.J.

    1981-02-01

    The effects of minerals and inexpensive ores or by-products (pyrites, red mud, flue dust, speculites, zinc sulfides, calcium oxide, dolomites, mica, molybdenite) in catalysing coal liquefaction or the hydrogenation of process solvents was studied with different cokes and solvents. Improved results were obtained in several cokes and th results are given in terms of oil fields, hydrogen consumption, desulfurization of SRC, etc. The addition of pyrite resulted in increased production of oils and increased conversion of coal; however, the effects varied from coal to coal. Dolomite, mica and molybdenite had insignificant catalytic activity. The reduction of pyrite, Fe/sub 2/O/sub 3/ and Fe/sub 3/O/sub 4/ at process conditions was studied. (LTN)

  2. Mechanism and Thermochemistry of Coal Char Oxidation and Desorption of Surface Oxides

    DEFF Research Database (Denmark)

    Levi, Gianluca; Causà, Mauro; Lacovig, Paolo

    2017-01-01

    The present study investigates the coal char combustion by a combination of thermochemical and X-ray photoemission spectroscopy (XPS) analyses. Thermoanalytical methods (differential thermogravimetry, differential scanning calorimetry, and temperature-programmed desorption) are used to identify...... the key reactive steps that occur upon oxidation and heating of coal char (chemisorption, structural rearrangement and switchover of surface oxides, and desorption) and their energetics. XPS is used to reveal the chemical nature of the surface oxides that populate the char surface and to monitor...... functionalities prevail. The rearrangement of epoxy during preoxidation goes together with activation of the more stable and less reactive carbon sites. Results are in good agreement with semi-lumped kinetic models of carbon oxidation, which include (1) formation of "metastable" surface oxides, (2) complex...

  3. Mechanism and kinetics of uranium adsorption onto soil around coal-fired power plant

    Science.gov (United States)

    Yasim, Nurzulaifa Shaheera Erne Mohd; Ariffin, Nik Azlin Nik; Mohammed, Noradila; Ayob, Syafina

    2017-11-01

    Coal is the largest source of energy in Malaysia providing approximately 80 % of all entire power needs. The combustion of coal concentrates a high content of heavy metals and radioactive elements in the ashes and sludge. Hazardous emissions from coal combustion were deposited into the soil and most likely transported into the groundwater system. The presence of radioactive materials in the ground water system can cause a wide range of environmental impacts and adverse health effects like cancer, impairment of neurological function and cardiovascular disease. However, the soil has a natural capability in adsorption of radioactive materials. Thus, this study was evaluated the adsorption capacity of Uranium onto the soil samples collected nearby the coal-fired power plants. In the batch experiment, parameters that were set constant include pH, the amount of soil and contact time. Various initial concentrations of radionuclides elements in the range of 2 mg/L - 10 mg/L were used. The equilibrium adsorption data was analyzed by the Freundlich isotherm and Langmuir isotherms. Then, the influences of solution pH, contact time and temperature on the adsorption process were investigated. The kinetics of radioactive materials was discussed by pseudo-first-order and pseudo-second-order rate equation. Thus, the data from this study could provide information about the potentiality of soil in sorption of radioactive materials that can be leached into groundwater. Besides that, this study could also be used as baseline data for future reference in the development of adsorption modeling in the calculation of distribution coefficient.

  4. The design of a mechanical referencing system for the rear drum of the Longwall Shearer Coal Miner

    Science.gov (United States)

    Jones, E. W.; Yang, T. C. H.

    1981-01-01

    The design of two systems which reference the position of a longwall shearer coal miner to the mine roof of the present cut and of the last cut are presented. This system is part of an automation system that will guide the rear cutting drum in such a manner that the total depth of cut remains constant even though the front drum may be following an undulating roof profile. The rear drum referencing mechanism continually monitors the distance from the mine roof to the floor for the present cut. This system provides a signal to control a constant depth of cut. The last cut follower mechanism continually monitors the distance from the mine roof of the prior cut to the cutting drum. This latter system provides a signal to minimize the step height in the roof between cuts. The dynamic response of this hydraulic-pneumatic and mechanical system is analyzed to determine accumulator size and precharge pressure.

  5. Coal geopolitics

    International Nuclear Information System (INIS)

    Giraud, P.N.; Suissa, A.; Coiffard, J.; Cretin, D.

    1991-01-01

    This book divided into seven chapters, describes coal economic cycle. Chapter one: coals definition; the principle characteristics and properties (origin, calorific power, international classification...) Chapter two: the international coal cycle: coal mining, exploration, coal reserves estimation, coal handling coal industry and environmental impacts. Chapter three: the world coal reserves. Chapter four: the consumptions, productions and trade. Chapter five: the international coal market (exporting mining companies; importing companies; distributors and spot market operators) chapter six: the international coal trade chapter seven: the coal price formation. 234 refs.; 94 figs. and tabs [fr

  6. Study of catalytic effects of mineral matter level on coal reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Mazzocco, Nestor J.; Klunder, Edgar B.; Krastman, Donald

    1981-03-01

    Coal liquefaction experiments using a 400-lb/day bubble-column reactor tested the catalytic effects of added mineral matter level on coal conversion, desulfurization, and distillate yields in continuous operation under recycle conditions, with specific emphasis on the use of a disposable pyrite catalyst indigenous to the feed coal. Western Kentucky No. 11 run-of-mine (ROM) and washed coals were used as feedstocks to determine the effects of levels of mineral matter, specifically iron compounds. Liquefaction reactivity as characterized by total distillate yield was lower for washed coal, which contained less mineral matter. Liquefaction reactivity was regained when pyrite concentrate was added as a disposable catalyst to the washed coal feed in sufficient quantity to match the feed iron concentration of the run-of-mine coal liquefaction test run.

  7. Formation of N2 in the fixed-bed pyrolysis of low rank coals and the mechanisms; Koteisho netsubunkai ni okeru teitankatan kara no N2 no sisei

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z.; Otsuka, Y. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

    1996-10-28

    In order to establish coal NOx preventive measures, discussions were given on formation of N2 in the fixed-bed pyrolysis of low rank coals and the mechanisms thereof. Chinese ZN coal and German RB coal were used for the discussions. Both coals do not produce N2 at 600{degree}C, and the main product is volatile nitrogen. Conversion into N2 does not depend on heating rates, but increases linearly with increasing temperature, and reaches 65% to 70% at 1200{degree}C. In contrast, char nitrogen decreases linearly with the temperature. More specifically, these phenomena suggest that the char nitrogen or its precursor is the major supply source of N2. When mineral substances are removed by using hydrochloric acid, their catalytic action is lost, and conversion into N2 decreases remarkably. Iron existing in ion-exchanged condition in low-rank coal is reduced and finely diffused into metallic iron particles. The particles react with heterocyclic nitrogen compounds and turn into iron nitride. A solid phase reaction mechanism may be conceived, in which N2 is produced due to decomposition of the iron nitride. 5 refs., 4 figs., 1 tab.

  8. Soil amendments promote vegetation establishment and control acidity in coal combustion waste

    Science.gov (United States)

    R.M. Danker; D.C. Adriano; Bon-Jun Koo; C.D. Barton

    2003-01-01

    The effects of adding various soil amendments and a pyrite oxidation inhibitor to aid in the establishment of vegetation and to reduce acid drainage (AD) from coal fly ash and coal reject (FA + CR*) were assessed in an outdoor mesocosm study. Preliminary greenhouse experiments and field observations at the U.S. Department of Energy's Savannah River Site (SRS)...

  9. Desulphurisation of coal pyrolysis and magnetic separation. Desulfuracion de carbones mediante pirolisis y separacion magnetica

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, J.C.; Ayala, N.; Ibarra, J.V.; Moliner, R.; Miranda, J.L.; Vazquez, A. (CENIM, Madrid (Spain))

    1991-07-01

    The desulphurisation of coal intended for use inthermal power stations is a priority issue in the national strategy for the reduction of acid rain. This article studies the feasibility of eliminating pyritic sulphur from coal by physical methods using high intensity pyrolysis and magnetic separation. 6 refs., 9 figs., 4 tabs.

  10. Mechanical characterization of Portland cement mortars containing petroleum or coal tar

    Directory of Open Access Journals (Sweden)

    Garcés, P.

    2007-08-01

    Full Text Available This article discusses experimental data on the flexural and compressive strength of Portland cement mortars containing additions or cement replacements consisting in petroleum or coal tar, by-products of the oil and coal industries. The materials studied were two coal (BACA and BACB and two petroleum (BPP and BPT tars. The results show that it is feasible to use such materials as a partial replacement for cement in mortar manufacture. This should lead to the design of a new sustainable product that will contribute to lowering the environmental impact of construction materials while at the same time opening up an avenue for the re-use of this type of industrial by-products.En este artículo se presentan datos experimentales de resistencia a flexión y a compresión de morteros de cemento Portland con adición y sustitución de breas de petróleo y de alquitrán de carbón, que son subproductos de la industria del carbón o del petróleo. Los materiales estudiados son breas de alquitrán de carbón A (BACA y B (BACB, y dos breas de petróleo (BPP y (BPT. Los datos demuestran la viabilidad del uso de estas breas en la fabricación de morteros con menores contenidos de cemento, permitiendo diseñar un nuevo material sostenible con el medio ambiente y que contribuya a reducir el impacto ambiental de los materiales de construcción, hecho que permite abrir una nueva vía de valorización de estos subproductos.

  11. Practical considerations of pyrite oxidation control in uranium tailings

    International Nuclear Information System (INIS)

    1984-05-01

    The problems posed by the oxidation of pyrite in uranium tailings include the generation of sulfuric acid and acid sulfate metal salts. These have substantial negative impacts on watercourse biota by themselves, and the lowered pH levels tend to mobilize heavy metals present in the tailings the rate of oxidation of pyrite at lower pH levels is catalyzed by sulfur and iron oxidizing bacteria present in soils. No single clear solution to the problems came from this study. Exclusion of air is a most important preventative of bacterial catalysis of oxidation. Bactericides, chemically breaking the chain of integrated oxidation reactions, maintaining anaerobic conditions, or maintaining a neutral or alkaline pH all reduce the oxidation rate. Removal of pyrite by flotation will reduce but not eliminate the impact of pyrite oxidation. Controlled oxidation of the remaining sulfide in the flotation tails would provide an innocuous tailing so far as acidity generation is concerned

  12. Chemical and sulphur isotope compositions of pyrite in the ...

    Indian Academy of Sciences (India)

    sulphide mineralization and their chemical evo- lution in relative .... properties and chemical compositions. Electron ..... from the sulphide lode provide clues to the chang- ing fluid ..... Raymond O L 1996 Pyrite composition and ore geneis in.

  13. Nonlinear Dynamics Mechanism of Rock Burst Induced by the Instability of the Layer-Crack Plate Structure in the Coal Wall in Deep Coal Mining

    Directory of Open Access Journals (Sweden)

    Yanlong Chen

    2017-01-01

    Full Text Available The instability of layer-crack plate structure in coal wall is one of the causes of rock burst. In the present paper, we investigate the formation and instability processes of layer-crack plate structure in coal wall by experiments and theoretical analysis. The results reveal that layer-crack plate structure formed near the free surface of the coal wall during the loading. During the formation of the layer-crack plate structure, the lateral displacement curve of the coal wall experiences a jagged variation, which suggests the nonlinear instability failure of the coal wall with a sudden release of the elastic energy. Then, a dynamic model for the stability analysis of the layer-crack plate structure was proposed, which takes consideration of the dynamic disturbance factor. Based on the dynamic model, the criterion for dynamic instability of the layer-crack plate structure was determined and demonstrated by an example. According to the analytical results, some control methods of dynamic stability of the layer-crack plate structure was put forward.

  14. Thermal dynamic analysis of sulfur removal from coal by electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.; Gao, J.; Meng, F. [Qinghua University, Beijing (China). Dept. of Thermal Engineering

    2002-06-01

    The electrolytic reactions about sulfur removal from coal were studied by using chemical thermal dynamic analysis. According to the thermodynamical data, the Gibbs free energy value of the electrolytic reactions of pyritic and organic sulfur removal from coal is higher than zero. So, these electrolytic reactions are not spontaneous chemical reactions. In order to carry out desulfurisation by electrolysis, a certain voltage is necessary and important. Because theoretic decomposition voltage of pyrite and some parts of organic sulfur model compound is not very high, electrolysis reactions are easily to be carried out by using electrolysis technology. Mn ion and Fe ion are added into electrolysis solutions to accelerate the desulfurisation reaction. The electrolytic decomposition of coal is discussed. Because the theoretical decomposition voltage of some organic model compound is not high, the coal decomposition might happen. 17 refs., 4 tabs.

  15. Spoil pile instabilities with reference to a strip coal mine in Turkey: mechanisms and assessment of deformations

    Science.gov (United States)

    Kasmer, Ozgu; Ulusay, Resat; Gokceoglu, Candan

    2006-02-01

    With the increasing adoption of the surface mining of coal, problems associated with spoil pile instability, which affects resource recovery, mining cost, and safety and presents environmental hazards, have become a matter of prime concern to mine planners and operators. The study of geotechnical aspects is thus very important in the rational planning for the disposal, reclamation, treatment and utilization of spoil material. A strip coal mine, one of the largest open pit mines in Turkey, is located in Central Anatolia and provides coal to a thermal power station. Coal production is carried out in two adjacent open pits, the Central Pit and South Pit. A large-scale spoil pile instability over an area of 0.3 km2 occurred within the dumping area of the Central pit. In addition, small-scale movement occurred in the outside dumping area. This paper outlines the results of field and laboratory investigations to describe the mechanisms of the spoil pile instabilities and to assess deformations monitored over a long period following the failure. Shear test results indicate that the interface between the floor and spoil material dumped by dragline has a negligible cohesion and is the most critical plane of weakness for spoil pile instability. Back analyses based on the method of limit equilibrium and the numerical modelling technique, and observations in the pit revealed that failure occurred along a combined sliding surface consisting of a circular surface through the spoil material itself and a planar surface passing along the interface between the spoil piles and floor. The analyses also indicated that pore water pressure ratios of about 0.25 satisfy limiting equilibrium condition and that rainfall about one month before the failure may be a contributing factor to the instability. Movement monitoring data obtained following the failure over a 1.5-year period suggested that the ongoing deformations were mainly due to compaction of the spoil material. Based on the

  16. Case Study on Incentive Mechanism of Energy Efficiency Retrofit in Coal-Fueled Power Plant in China

    Directory of Open Access Journals (Sweden)

    Donghai Yuan

    2012-01-01

    Full Text Available An ordinary steam turbine retrofit project is selected as a case study; through the retrofit, the project activities will generate emission reductions within the power grid for about 92,463 tCO2e per annum. The internal rate of return (IRR of the project is only −0.41% without the revenue of carbon credits, for example, CERs, which is much lower than the benchmark value of 8%. Only when the unit price of carbon credit reaches 125 CNY/tCO2, the IRR could reach the benchmark and an effective carbon tax needs to increase the price of carbon to 243 CNY/tce in order to make the project financially feasible. Design of incentive mechanism will help these low efficiency enterprises improve efficiency and reduce CO2 emissions, which can provide the power plants sufficient incentive to implement energy efficiency retrofit project in existing coal-fuel power generation-units, and we hope it will make a good demonstration for the other low efficiency coal-fueled power generation units in China.

  17. Case Study on Incentive Mechanism of Energy Efficiency Retrofit in Coal-Fueled Power Plant in China

    Science.gov (United States)

    Yuan, Donghai; Guo, Xujing; Cao, Yuan; He, Liansheng; Wang, Jinggang; Xi, Beidou; Li, Junqi; Ma, Wenlin; Zhang, Mingshun

    2012-01-01

    An ordinary steam turbine retrofit project is selected as a case study; through the retrofit, the project activities will generate emission reductions within the power grid for about 92,463 tCO2e per annum. The internal rate of return (IRR) of the project is only −0.41% without the revenue of carbon credits, for example, CERs, which is much lower than the benchmark value of 8%. Only when the unit price of carbon credit reaches 125 CNY/tCO2, the IRR could reach the benchmark and an effective carbon tax needs to increase the price of carbon to 243 CNY/tce in order to make the project financially feasible. Design of incentive mechanism will help these low efficiency enterprises improve efficiency and reduce CO2 emissions, which can provide the power plants sufficient incentive to implement energy efficiency retrofit project in existing coal-fuel power generation-units, and we hope it will make a good demonstration for the other low efficiency coal-fueled power generation units in China. PMID:23365532

  18. Case study on incentive mechanism of energy efficiency retrofit in coal-fueled power plant in China.

    Science.gov (United States)

    Yuan, Donghai; Guo, Xujing; Cao, Yuan; He, Liansheng; Wang, Jinggang; Xi, Beidou; Li, Junqi; Ma, Wenlin; Zhang, Mingshun

    2012-01-01

    An ordinary steam turbine retrofit project is selected as a case study; through the retrofit, the project activities will generate emission reductions within the power grid for about 92,463 tCO(2)e per annum. The internal rate of return (IRR) of the project is only -0.41% without the revenue of carbon credits, for example, CERs, which is much lower than the benchmark value of 8%. Only when the unit price of carbon credit reaches 125 CNY/tCO(2), the IRR could reach the benchmark and an effective carbon tax needs to increase the price of carbon to 243 CNY/tce in order to make the project financially feasible. Design of incentive mechanism will help these low efficiency enterprises improve efficiency and reduce CO(2) emissions, which can provide the power plants sufficient incentive to implement energy efficiency retrofit project in existing coal-fuel power generation-units, and we hope it will make a good demonstration for the other low efficiency coal-fueled power generation units in China.

  19. Mobility of the element aluminium in the weathering of hard coal material containing pyrites. Investigations on piled-up clay and silt stones of the Upper Carbon layer. Mobilitaet des Elementes Aluminium bei der Verwitterung von pyrithaltigem Steinkohlenbergematerial. Untersuchungen an aufgehaldeten Ton- und Siltsteinen des Oberkarbons

    Energy Technology Data Exchange (ETDEWEB)

    Finke, G

    1992-06-17

    In connection with the recultivation problems of mining material, investigations were made of the mobility and toxicity of aluminium in the course of weathering of mining material containing upper carbonic pyrites, and particular attention was paid to interaction of the aluminium with other ions in the weathering solution. From the aluminium type, from the ratios of Ca/Al, Al/SO[sub 4] and Al/TOC, and based on these investigations, the aluminium factor can probably be excluded as the main cause of the difficult recultivation and re-greening of mining material in the first decade of weathering. Only certain types of aluminium have toxic effects. These include ionic aluminium and different aluminium hydroxy compounds. Sulphate, fluoride, nitrate compounds of aluminium and organic aluminium compounds have not proved to be toxic. The proportion of aluminium in the ion pool can be decisive, as shown by the Ca/Al ratio. The ratio of these two cations determines the degree of danger from aluminium, depending on the type of plant. (orig.)

  20. The Effect of Water Vapor on the Thermal Decomposition of Pyrite in N2 Atmosphere

    Directory of Open Access Journals (Sweden)

    Nesrin BOYABAT

    2009-03-01

    Full Text Available In this study, the effect of water vapor on the thermal decomposition of pyrite mineral in nitrogen atmosphere has been investigated in a horizontal tube furnace. Temperature, time and water vapor concentration were used as experimental parameters. According to the data obtained at nitrogen/ water vapor environment, it was observed that the water vapor on the decomposition of pyrite increased the decomposition rate. The decomposition reaction is well represented by the "shrinking core" model and can be divided into two regions with different rate controlling step. The rate controlling steps were determined from the heat transfer through the gas film for the low conversions, while it was determined from the mass transfer through product ash layer for the high conversions. The activation energies of this gas and ash film mechanisms were found to be 77 and 81 kJ/mol-1, respectively.

  1. Preparation of Metallic Iron Powder from Pyrite Cinder by Carbothermic Reduction and Magnetic Separation

    Directory of Open Access Journals (Sweden)

    Hongming Long

    2016-04-01

    Full Text Available The reduction and magnetic separation procedure of pyrite cinder in the presence of a borax additive was performed for the preparation of reduced powder. The effects of borax dosage, reduction temperature, reduction time and grinding fineness were investigated. The results show that when pyrite cinder briquettes with 5% borax were pre-oxidized at 1050 °C for 10 min, and reduced at 1050 °C for 80 min, with the grinding fineness (<0.44 mm passing 81%, the iron recovery was 91.71% and the iron grade of the magnetic concentrate was 92.98%. In addition, the microstructures of the products were analyzed by optical microscope, scanning electron microscope (SEM, and mineralography, and the products were also studied by the X-ray powder diffraction technique (XRD to investigate the mechanism; the results show that the borax additive was approved as a good additive to improve the separation of iron and gangue.

  2. Moessbauer investigation of gold-bearing pyrite-rich concentrates

    International Nuclear Information System (INIS)

    Wagner, F.E.; Harris, D.C.

    1994-01-01

    A gold-bearing pyrite-rich concentrate of a refractory ore from the Golden Bear mine, northwestern British Columbia, and a pyrite-rich concentrate from Newhawk's west zone, Brucejack Lake area, northern British Columbia, containing 38 and 316 ppm Au and 0.57% and 0.19% As, respectively, have been investigated using 197 Au and 57 Fe Moessbauer spectroscopy. In the Golden Bear sample, the gold is mainly chemically bound in the pyrite with minor amounts present as an Au-Ag alloy, whereas in the Newhawk sample, the gold occurs mainly as an Au-Ag alloy with a composition close to Au 0.5 Ag 0.5 and is only partly bound in the pyrite. Having mean isomer shifts of +3.2 and +4.0 mm/s with respect to a Pt metal source, the gold in pyrite exhibits shifts similar to those observed for gold in arsenopyrite. The nature of the lattice sites occupied by the gold in pyrite is discussed. (orig.)

  3. The effect of lizardite surface characteristics on pyrite flotation

    International Nuclear Information System (INIS)

    Feng Bo; Feng Qiming; Lu Yiping

    2012-01-01

    Highlights: ► Two kinds of lizardite samples have different effect on the flotation of pyrite. ► Acid leaching changed the surface characteristics of lizardite mineral. ► The leached lizardite has less magnesium on its surface. ► The electro-kinetic behavior of lizardite aqueous suspensions is mainly a function of the Mg/Si atomic ratio on mineral surface. - Abstract: The effect of lizardite surface characteristics on pyrite flotation has been investigated through flotation tests, adsorption tests, zeta potential measurements, FTIR study, X-ray photoelectron spectroscopy (XPS) and sedimentation tests. The flotation results show that at pH value 9, where flotation of nickel sulfide ores is routinely performed, two kinds of lizardite samples (native lizardite and leached lizardite) have different effects on the flotation of pyrite. The native lizardite adheres to the surface of pyrite and reduces pyrite flotation recovery while the leached lizardite does not interfere with pyrite flotation. Infrared analyses and XPS tests illustrate that acid leaching changed the surface characteristics of lizardite mineral and the leached lizardite has less magnesium on its surface. It has been determined that the electro-kinetic behavior of lizardite aqueous suspensions is mainly a function of the Mg/Si atomic ratio on lizardite surface. So, the low isoelectric point observed in the leached sample has been linked to values of this ratio lower than that of the native lizardite.

  4. Spectral Induced Polarization of Disseminated Pyrite Particles in Soil

    Science.gov (United States)

    Slater, L. D.; Kessouri, P.; Seleznev, N. V.

    2017-12-01

    Disseminated metallic particles in soil, particularly pyrite, occur naturally or are enhanced by anthropogenic activities. Detecting their presence and quantifying their concentration and location is of interest for numerous applications such as remediation of hydrocarbon contamination, mine tailings assessment, detection of oil traps, and archaeological studies. Because pyrite is a semiconductor, spectral induced polarization (SIP) is a promising geophysical method for sensing it in porous media. Previous studies have identified relations between pyrite properties (e.g., volumetric content, grain size) and SIP parameters (e.g., chargeability, relaxation time). However, the effect of pyrite grains in porous media on the SIP response is not fully understood over the entire low-frequency range. We tested the relationship between the presence of pyrite grains and the change in electrical properties of the medium through an extended series of laboratory measurements: (1) variation of grain size, (2) variation of grain concentration, (3) variation of electrolyte conductivity, (4) change in the diffusion properties of the host medium. For the fourth set of measurements, we compared sand columns to agar gel columns. Our experimental design included more than 20 different samples with multiple repeats to ensure representative results. We confirm the strong relation between grain size and relaxation time and that between grain concentration and chargeability in both the sand and agar gel samples. Furthermore, our results shed light on the significance of the diffusion coefficient and the recently hypothesized role of pyrite grains as resistors at frequencies lower than the relaxation frequency.

  5. SULPHIDE MINERALIZATION IN UPPER WESTPHALIAN COAL SEAMS FROM THE EASTERN PART OF THE UPPER SILESIAN COAL BASIN

    Directory of Open Access Journals (Sweden)

    Lipiarski Ireneusz

    1997-10-01

    Full Text Available Morphologically diversified sulphide mineralization has been found in No. 301 and 302 coal seams (Westphalian B. The main sulphide is pyrite which forms veinlets cross-cutting the sedimentary fabrics of the coal, encrusts the cellular structures and intergrowths with oxysulphides. Two generations of pyrites were observed: the preceding and the following the oxysulphides. Pyrite composition is stoichiometric, rare admixtures are up to(in wt.%: Mn - 0.19, Co - 0.48, Ni - 0.42 and As - 1.41. Iron oxysulphides contain up to 35.06 wt.% oxygen. Their composition varies between FeS2O and FeS2O3. Increased contents of As (up to 1.46 wt.% and Pb (up to 0.96 wt.% were detected.

  6. Effect of Phospholipid on Pyrite Oxidation and Microbial Communities under Simulated Acid Mine Drainage (AMD) Conditions.

    Science.gov (United States)

    Pierre Louis, Andro-Marc; Yu, Hui; Shumlas, Samantha L; Van Aken, Benoit; Schoonen, Martin A A; Strongin, Daniel R

    2015-07-07

    The effect of phospholipid on the biogeochemistry of pyrite oxidation, which leads to acid mine drainage (AMD) chemistry in the environment, was investigated. Metagenomic analyses were carried out to understand how the microbial community structure, which developed during the oxidation of pyrite-containing coal mining overburden/waste rock (OWR), was affected by the presence of adsorbed phospholipid. Using columns packed with OWR (with and without lipid adsorption), the release of sulfate (SO4(2-)) and soluble iron (FeTot) was investigated. Exposure of lipid-free OWR to flowing pH-neutral water resulted in an acidic effluent with a pH range of 2-4.5 over a 3-year period. The average concentration of FeTot and SO4(2-) in the effluent was ≥20 and ≥30 mg/L, respectively. In contrast, in packed-column experiments where OWR was first treated with phospholipid, the effluent pH remained at ∼6.5 and the average concentrations of FeTot and SO4(2-) were ≤2 and l.6 mg/L, respectively. 16S rDNA metagenomic pyrosequencing analysis of the microbial communities associated with OWR samples revealed the development of AMD-like communities dominated by acidophilic sulfide-oxidizing bacteria on untreated OWR samples, but not on refuse pretreated with phospholipid.

  7. Effects of coal and wheat husk additives on the physical, thermal and mechanical properties of clay bricks

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, S.; Iqbal, Y.; Muhammad, R.

    2017-07-01

    The use of by-products as additives in brick industry is gaining increased research attention due to their effective role in decreasing the total energy needs of industrial furnaces. In addition, these additives leave pores upon burning, causing a decrease in thermal conductivity and affect the mechanical properties of bricks as well. In the present study, various proportions of coal and wheat husk were used as additives in the initial ingredients of clay bricks. Microstructure, thermal conductivity, coefficient of thermal diffusivity, water absorption, shrinkage, compressive strength and bulk density of fired clay bricks with and without additives were investigated. Clay bricks containing 5–15wt.% additives were found to be within the permissible limits for most of the recommended standard specifications. (Author)

  8. Mechanical properties of coal deformation and its influence on permeability%煤岩变形力学特性及其对渗透性的控制

    Institute of Scientific and Technical Information of China (English)

    孟召平; 王保玉; 谢晓彤; 薛彦东; 杜星原

    2012-01-01

    By the mechanical tests of the coal samples, the physical and mechanical properties of coal and the law of permeability during the complete stress-strain process were studied. It is shown that, compared with the rocks from coal roof and floor, the coal is more prone to plastic deformation with the property of lower mechanical strength, lower elastic modulus and higher Poisson' s ratio. For the coal samples which have obvious strain-softening character during the complete stress-strain process,first,the coal sample volume is compressed and the permeability of coal with stress in- creases slightly or permeability changes little in the micro-cracks closure and elastic deformation stage. After the stress increases higher than the elastic limit, the coal sample gets into the crack propagation stage. The volume strain of coal changs from compression to expansion. The permeability of coal first slowly and then sharply increases with an increas- ing of crack extension. During the strain-softening stage ,the coal permeability achieves the maximum and follows by a sharp decrease. The coal pel~neability after the peak strength is generally greater than that before the peak. For coal samples which have little strain-softening character or strain-hardening during the complete stress-strain process, the maximum permeability is mainly achieved in the plastic deformation stage before the peak. During the strain-hardening stage after the peak strength, the permeability decreases with an increasing of stress. Commonly, the coal permeability after the peak strength is generally less than that before the peak.%通过煤岩力学试验研究了煤岩物理力学性质和煤岩全应力-应变过程中的渗透规律。研究结果表明:煤的力学强度相对煤层顶底板岩石具有低强度、低弹性模量和高泊松比特性,易于产生塑性变形;在全应力-应变过程中具有明显应变软化现象的煤样,在微裂隙闭合和弹性变形阶段,煤岩体积被

  9. Control Mechanism of Rock Burst in the Floor of Roadway Driven along Next Goaf in Thick Coal Seam with Large Obliquity Angle in Deep Well

    Directory of Open Access Journals (Sweden)

    Yunhai Cheng

    2015-01-01

    Full Text Available This paper deals with the theoretical aspects combined with stress analysis over the floor strata of coal seam and the calculation model for the stress on the coal floor. Basically, this research presents the relevant results obtained for the rock burst prevention in the floor of roadway driven along next goaf in the exploitation of thick coal seam with large obliquity in deep well and rock burst tendency. The control mechanism of rock burst in the roadway driven along next goaf is revealed in the present work. That is, the danger of rock burst can be removed by changing the stress environment for the energy accumulation of the floor and by reducing the impact on the roadway floor from the strong dynamic pressure. This result can be profitable being used at the design stage of appropriate position of roadway undergoing rock burst tendency in similar conditions. Based on the analysis regarding the control mechanism, this paper presents a novel approach to the prevention of rock burst in roadway floor under the above conditions. That is, the return airway is placed within the goaf of the upper working face that can prevent the rock burst effectively. And in this way, mining without coal pillar in the thick coal seam with large obliquity and large burial depth (over a thousand meters is realized. Practice also proves that the rock burst in the floor of roadway driven along next goaf is controlled and solved.

  10. Experimental study of desulfurization of Zhong Liang Shau high sulfur coal by flotation

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Z.; Huang, B.; Cao, J. [China University of Mining and Technology (China). Beijing Graduate School

    1994-12-01

    Emission of large amount of SO{sub 2} from combustion of high sulfur coal causes serious environmental pollution. Pre-combustion desulfurization of high sulfur coal has become a necessity. This paper reports test results of fine coal desulfurization with different flotation technology and the effect of pyrite depressant. Test work showed that when the coal sample from Zhong Liang Shau was processed with a Free Jet Flotation Column its pyritic sulfur content was reduced from 3.08% to 0.84%, with 72.22% recovery of combustible matter in clean coal. The concept of Desulfurization Efficiency Index E{sub ds} for comprehensive evaluation of desulfurization process is proposed, which is defined as the product of the ratio of sulfur content reduction of clean coal and the recovery of combustible matters. 6 refs., 4 figs., 3 tabs.

  11. Influence of mechanical activation on the synthesis of Sr-Celsian employing a precursor mixture containing coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Badillo, C. M.; Lopez-Cuevas, J.; Rodriguez-Galicia, J. L.; Gutierrez-Chavarria, C. A.; Pech-Canul, M. I.

    2013-05-01

    Strontium aluminosilicate, SrAl{sub 2}Si{sub 2}O{sub 8} (SAS), was synthesized by a solid state reaction using coal fly ash (CFA) as main raw material. A precursor mixture of SrCO{sub 3}, CFA and Al{sub 2}O{sub 3} was mechanically-activated for times of up to 12 h using an attrition mill, and subsequently sintered at temperatures of 900-1300 degree centigrade. The CFA and the mechanical activation were employed with the aim to promote the transformation from the hexagonal (Sr-Hexacelsian) into the monoclinic (Sr-Celsian) polymorphic form of SAS, since the latter phase is associated with better physical and mechanical properties but the former tends to be the first one to appear. The mean particle size, the crystallite size and the temperature at the end of the curve of weight loss (Tf) decreased, while the specific surface area and the degree of amorphization increased, with increasing milling time. Samples milled for at least 4 h and then sintered at 1100 degree centigrade achieved full transformation into Sr-Celsian. The same result was obtained for sintering temperatures higher than 1100 degree centigrade, independently of milling time. An increment in both the milling time and the sintering temperature allowed us to improve the densification and the mechanical properties of the synthesized materials. (Author) 24 refs.

  12. Influence of mechanical activation on the synthesis of Sr-Celsian employing a precursor mixture containing coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Badillo, C. M.; Lopez-Cuevas, J.; Rodriguez-Galicia, J. L.; Gutierrez-Chavarria, C. A.; Pech-Canul, M. I.

    2013-06-01

    Strontium aluminosilicate, SrAl{sub 2}Si{sub 2}O{sub 8} (SAS), was synthesized by a solid state reaction using coal fly ash (CFA) as main raw material. A precursor mixture of SrCO{sub 3}, CFA and Al{sub 2}O{sub 3} was mechanically-activated for times of up to 12 h using an attrition mill, and subsequently sintered at temperatures of 900-1300 degree centigrade. The CFA and the mechanical activation were employed with the aim to promote the transformation from the hexagonal (Sr-Hexacelsian) into the monoclinic (Sr-Celsian) polymorphic form of SAS, since the latter phase is associated with better physical and mechanical properties but the former tends to be the first one to appear. The mean particle size, the crystallite size and the temperature at the end of the curve of weight loss (Tf) decreased, while the specific surface area and the degree of amorphization increased, with increasing milling time. Samples milled for at least 4 h and then sintered at 1100 degree centigrade achieved full transformation into Sr-Celsian. The same result was obtained for sintering temperatures higher than 1100 degree centigrade, independently of milling time. An increment in both the milling time and the sintering temperature allowed us to improve the densification and the mechanical properties of the synthesized materials. (Author)

  13. Influence of mechanical activation on the synthesis of Sr-Celsian employing a precursor mixture containing coal fly ash

    International Nuclear Information System (INIS)

    Lopez-Badillo, C. M.; Lopez-Cuevas, J.; Rodriguez-Galicia, J. L.; Gutierrez-Chavarria, C. A.; Pech-Canul, M. I.

    2013-01-01

    Strontium aluminosilicate, SrAl 2 Si 2 O 8 (SAS), was synthesized by a solid state reaction using coal fly ash (CFA) as main raw material. A precursor mixture of SrCO 3 , CFA and Al 2 O 3 was mechanically-activated for times of up to 12 h using an attrition mill, and subsequently sintered at temperatures of 900-1300 degree centigrade. The CFA and the mechanical activation were employed with the aim to promote the transformation from the hexagonal (Sr-Hexacelsian) into the monoclinic (Sr-Celsian) polymorphic form of SAS, since the latter phase is associated with better physical and mechanical properties but the former tends to be the first one to appear. The mean particle size, the crystallite size and the temperature at the end of the curve of weight loss (Tf) decreased, while the specific surface area and the degree of amorphization increased, with increasing milling time. Samples milled for at least 4 h and then sintered at 1100 degree centigrade achieved full transformation into Sr-Celsian. The same result was obtained for sintering temperatures higher than 1100 degree centigrade, independently of milling time. An increment in both the milling time and the sintering temperature allowed us to improve the densification and the mechanical properties of the synthesized materials. (Author)

  14. Advanced physical fine coal cleaning spherical agglomeration. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1990-09-01

    The project included process development, engineering, construction, and operation of a 1/3 tph proof-of-concept (POC) spherical agglomeration test module. The POC tests demonstrated that physical cleaning of ultrafine coal by agglomeration using heptane can achieve: (1) Pyritic sulfur reductions beyond that possible with conventional coal cleaning methods; (2) coal ash contents below those which can be obtained by conventional coal cleaning methods at comparable energy recoveries; (3) energy recoveries of 80 percent or greater measured against the raw coal energy content; (4) complete recovery of the heptane bridging liquid from the agglomerates; and (5) production of agglomerates with 3/8-inch size and less than 30 percent moisture. Test results met or exceeded all of the program objectives. Nominal 3/8-inch size agglomerates with less than 20 percent moisture were produced. The clean coal ash content varied between 1.5 to 5.5 percent by weight (dry basis) depending on feed coal type. Ash reductions of the run-of-mine (ROM) coal were 77 to 83 percent. ROM pyritic sulfur reductions varied from 86 to 90 percent for the three test coals, equating to total sulfur reductions of 47 to 72 percent.

  15. Research on mechanism of and catalysts for extraction liquefaction of coal using coal-based solvents; Sekitankei yozai ni yoru sekitan no chushutsu ekika kiko to shokubai no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1981-07-01

    Papers of Professor Yoshio Kamiya of Tokyo University are compiled into this report. The list of the papers includes (1) Synthesis of heavy fuel oils from coal; (2) Research and development of coal liquefaction; (3) Dissolution reaction of coal by hydrogen-donating aromatic solvents (I); (4) Effect of hydrogen-donor solvent on the liquefaction of coal; (5) Recent studies on the chemical structure of solvent refined coal; (6) Dissolution reaction of coal by hydrogen-donating aromatic solvents (II); (7) Future of coal as energy material; (8), (9), (10) same as (6) in the subject discussed; (11) Recent studies on coal liquefaction catalysts; (12) Environmental problems and drain treatment to accompany processes of converting fossil resources into fuels; (13) Chemistry of coal oxidation; (14) Fractionation and analysis of solvent refined coal by gel permeation chromatography; (15) Current state of research and development of coal liquefaction; (16) Properties and components of coal oils from coal liquefaction processes under development; (17) Solvent effect of coal derived aromatic compounds on the liquefaction of Akabira coal; (18) Chemistry of coal liquefaction; (19) Research and development of coal liquefaction in the U.S.; (20) Thermal treatment of coal-related aromatic ethers in tetralin solution; (21) Recent technology of utilizing heavy carbon resources; (22) Chemical properties and reactivity of coal; (23) Current state and future of development of coal liquefaction processes; and (24) Development of overseas coal liquefaction projects. (NEDO)

  16. Surface Chemical Characterisation of Pyrite Exposed to Acidithiobacillus ferrooxidans and Associated Extracellular Polymeric Substances

    Directory of Open Access Journals (Sweden)

    Sian M. La Vars

    2018-03-01

    Full Text Available A. ferrooxidans and their metabolic products have previously been explored as a viable alternative depressant of pyrite for froth flotation; however, the mechanism by which separation is achieved is not completely understood. Scanning electron microscopy (SEM, photoemission electron microscopy (PEEM, time-of-flight secondary ion mass spectrometry (ToF-SIMS and captive bubble contact angle measurements have been used to examine the surface physicochemical properties of pyrite upon exposure to A. ferrooxidans grown in HH medium at pH 1.8. C K-edge near edge X-ray absorption fine structure (NEXAFS spectra collected from PEEM images indicate hydrophilic lipids, fatty acids and biopolymers are formed at the mineral surface during early exposure. After 168 h, the spectra indicate a shift towards protein and DNA, corresponding to an increase in cell population and biofilm formation on the surface, as observed by SEM. The Fe L-edge NEXAFS show gradual oxidation of the mineral surface from Fe(II sulfide to Fe(III oxyhydroxides. The oxidation of the iron species at the pyrite surface is accelerated in the presence of A. ferrooxidans and extracellular polymeric substances (EPS as compared to HH medium controls. The surface chemical changes induced by the interaction with A. ferrooxidans show a significant decrease in surface hydrophobicity within the first 2 h of exposure. The implications of these findings are the potential use of EPS produced during early attachment of A. ferrooxidans, as a depressant for bioflotation.

  17. Effects of fractal pore on coal devolatilization

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yongli; He, Rong [Tsinghua Univ., Beijing (China). Dept. of Thermal Engineering; Wang, Xiaoliang; Cao, Liyong [Dongfang Electric Corporation, Chengdu (China). Centre New Energy Inst.

    2013-07-01

    Coal devolatilization is numerically investigated by drop tube furnace and a coal pyrolysis model (Fragmentation and Diffusion Model). The fractal characteristics of coal and char pores are investigated. Gas diffusion and secondary reactions in fractal pores are considered in the numerical simulations of coal devolatilization, and the results show that the fractal dimension is increased firstly and then decreased later with increased coal conversions during devolatilization. The mechanisms of effects of fractal pores on coal devolatilization are analyzed.

  18. Method selection for mercury removal from hard coal

    Directory of Open Access Journals (Sweden)

    Dziok Tadeusz

    2017-01-01

    Full Text Available Mercury is commonly found in coal and the coal utilization processes constitute one of the main sources of mercury emission to the environment. This issue is particularly important for Poland, because the Polish energy production sector is based on brown and hard coal. The forecasts show that this trend in energy production will continue in the coming years. At the time of the emission limits introduction, methods of reducing the mercury emission will have to be implemented in Poland. Mercury emission can be reduced as a result of using coal with a relatively low mercury content. In the case of the absence of such coals, the methods of mercury removal from coal can be implemented. The currently used and developing methods include the coal cleaning process (both the coal washing and the dry deshaling as well as the thermal pretreatment of coal (mild pyrolysis. The effectiveness of these methods various for different coals, which is caused by the diversity of coal origin, various characteristics of coal and, especially, by the various modes of mercury occurrence in coal. It should be mentioned that the coal cleaning process allows for the removal of mercury occurring in mineral matter, mainly in pyrite. The thermal pretreatment of coal allows for the removal of mercury occurring in organic matter as well as in the inorganic constituents characterized by a low temperature of mercury release. In this paper, the guidelines for the selection of mercury removal method from hard coal were presented. The guidelines were developed taking into consideration: the effectiveness of mercury removal from coal in the process of coal cleaning and thermal pretreatment, the synergy effect resulting from the combination of these processes, the direction of coal utilization as well as the influence of these processes on coal properties.

  19. Development of decision- making mechanism in engineering design of phased coal mines technical upgrade

    Science.gov (United States)

    Kulak, V. Yu; Petrova, T. V.; Novichikhin, A. V.

    2017-09-01

    The approach to a choice of a new mine design and technical upgrade of operating coal mines is substantiated. The choice of the option is made in the following way: the elements of the mine technological system are defined, for each element of the system two levels of costs are allocated - capital and operational; a graph of alternative options of the system is formed by matrix enumeration taking into account the possibility of simultaneous application of different elements, up to 10 000 scenarios are formed; capital and operating costs of options are estimated in the form of coefficients as the cost-to-cost ratio in the base variant, which has already been implemented and the costs of which are already known; ranking of the options at the level of costs and the definition of the 10 preferred are performed. It is established that the application of partial enumeration allows the costs relative to the base variant to be reduced by 10 %; the main constraint of costs reduction is the need to comply with all conditions that ensure industrial safety.

  20. Seventh symposium on coal mine drainage research. NCA/BCR coal conference and Expo IV

    Energy Technology Data Exchange (ETDEWEB)

    None

    1977-01-01

    The Seventh Symposium on Coal Mine Drainage Research, sponsored by the National Coal Association and Bituminous Coal Research, Inc., was held at the Kentucky Fair and Exposition Center, Louisville, Kentucky, October 18-20, 1977. Seventeen papers from the proceedings have been entered individually into EDB and ERA. Topics covered include chemical reactions of pyrite oxidation and acid formation in spoil banks, abandoned mines, etc., formation of small acid lakes from the drainage and their neutralization by natural and other neutralization measures, trace elements in acid mine drainage, ground water contamination, limnology, effects of surface mined ground reclamation and neutralization, water purification and treatment, mining and coal preparation plant waste disposal, ash and fly ash disposal (to minimize leaching from the wastes), runoff from large coal storage stockpiles during storms (prevention of environmental effects by collection and neutralization by passing through an ash pond). (LTN)

  1. Pyritic ash-flow tuff, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Castor, S.B.; Tingley, J.V.; Bonham, H.F. Jr.

    1994-01-01

    The Yucca Mountain site is underlain by a 1,500-m-thick Miocene volcanic sequence that comprises part of the southwestern Nevada volcanic field. Rocks of this sequence, which consists mainly of ash-flow tuff sheets with minor flows and bedded tuff, host precious metal mineralization in several areas as near as 10 km from the site. In two such areas, the Bullfrog and Bare Mountain mining districts, production and reserves total over 60 t gold and 150 t silver. Evidence of similar precious metal mineralization at the Yucca Mountain site may lead to mining or exploratory drilling in the future, compromising the security of the repository. The authors believe that most of the pyrite encountered by drilling at Yucca Mountain was introduced as pyroclastic ejecta, rather than by in situ hydrothermal activity. Pyritic ejecta in ash-flow tuff are not reported in the literature, but there is no reason to believe that the Yucca Mountain occurrence is unique. The pyritic ejecta are considered by us to be part of a preexisting hydrothermal system that was partially or wholly destroyed during eruption of the tuff units. Because it was introduced as ejecta in tuff units that occur at depths of about 1,000 m, such pyrite does not constitute evidence of shallow mineralization at the proposed repository site; however, the pyrite may be evidence for mineralization deep beneath Yucca Mountain or as much as tens of kilometers from it

  2. Hydrogeologic and environmental impact of amjhore pyrite mines, India

    Science.gov (United States)

    Choubey, Vishnu D.; Rawat, Rajendra K.

    1991-01-01

    Drainage from active and inactive pyrite mines has produced chemical and physical pollution of both ground- and surface water in Amjhore region. In the present case, chemical pollution is caused by exposing pyrite minerals to oxidation or leaching, resulting in undesirable concentrations of dissolved materials. Pyrite mining suddenly exposed large quantities of sulfides to direct contact with oxygen, and oxidation proceeds rapidly, resulting in acidity and release of metal (Fe) and sulfates to the water system, eventually resulting in water pollution in the region. The magnitude and impact of the problem is just being recognized and, as the present and the future projected demand for clean water is of top priority, the present studies were undertaken. Mine drainage includes water flowing from the surface and underground mines and runoff or seepage from the pyrite mines. This article describes the various hydrologic factors that control acid water formation and its transport. The mine drainage is obviously a continuing source of pollution and, therefore, remedial measures mainly consisting of a double-stage limestone-lime treatment technique have been suggested. The present results will be used to develop an alternative and more effective abatement technology to mitigate acid production at the source, namely, the technique of revegetation of the soil cover applied to the waste mine dump material. Water quality change is discussed in detail, with emphasis on acidity formed from exposed pyrite material and on increase in dissolved solids. Preventive and treatment measures are recommended.

  3. The flotation of gold, uranium, and pyrite from Witwatersrand ores

    International Nuclear Information System (INIS)

    Lloyd, P.J.D.

    1981-01-01

    The Witwatersrand reefs contain gold, uranium, and pyrite in the following average concentrations: 0,001 per cent, 0,02 per cent, and 1,7 per cent respectively. The paper discusses the flotation of pyrite to produce a sulphide concentrate, reviews work done on the production of gold concentrates, discusses attempts to produce maximum concentrates, and closes with a review of processes for the simultaneous flotation of these three species. It is concluded that high recoveries of all three species can be achieved only if a rougher concentrate of perhaps 20 per cent of the feed (by mass) is produced, and it is suggested that reverse leaching (leaching before cyanidation) of this concentrate, followed by a cleaning flotation step for the recovery of the pyrite, would be more efficient than the routes employed at present [af

  4. Mercury distribution in coals influenced by magmatic intrusions, and surface waters from the Huaibei Coal Mining District, Anhui, China

    International Nuclear Information System (INIS)

    Yan, Zhicao; Liu, Guijian; Sun, Ruoyu; Wu, Dun; Wu, Bin; Zhou, Chuncai

    2013-01-01

    Highlights: • Hg concentrations in coal and surface water samples were determined. • Hg is enriched in the Huaibei coals. • Magmatic activities imparted influences on Hg content and distribution. • Hg contents in surface waters are relative low at the present status. - Abstract: The Hg concentrations in 108 samples, comprising 81 coal samples, 1 igneous rock, 2 parting rock samples and 24 water samples from the Huaibei Coal Mining District, China, were determined by cold-vapor atomic fluorescence spectrometry. The abundance and distribution of Hg in different coal mines and coal seams were studied. The weighted average Hg concentration for all coal samples in the Huaibei Coalfield is 0.42 mg/kg, which is about twice that of average Chinese coals. From southwestern to northeastern coalfield, Hg concentration shows a decreasing trend, which is presumably related to magmatic activity and fault structures. The relatively high Hg levels are observed in coal seams Nos. 6, 7 and 10 in the southwestern coal mines. Correlation analysis indicates that Hg in the southwestern and southernmost coals with high Hg concentrations is associated with pyrite. The Hg concentrations in surface waters in the Huaibei Coal Mining District range from 10 to 60 ng/L, and display a decreasing trend with distance from a coal waste pile but are lower than the regulated levels for Hg in drinking water

  5. Biodesulphurisation of high sulphur coal by heap leaching

    Energy Technology Data Exchange (ETDEWEB)

    J. Cara; M.T. Carballo; A. Moran; D. Bonilla; O. Escolano; F.J. Garcia Frutos [Universidad de Leon, Leon (Spain). Departamento de Ingenieria Quimica

    2005-10-01

    The biodesulphurisation of coal carried out in pile could be an interesting option to clean coal. In view of the good results obtained in biodesulphurisation test column at lab scale on a sample of semianthracite coal that proceed of an industrial plant with a high sulphur content, mainly pyritic sulphur, the feasibility of the process at pilot plant scale was studied. The pile was formed with 6 ton of gravity middlings coal sample with a grain size -12+0.5 mm from S.A. Hullera Vasco-Leonesa industrial plant. The coal has a total sulphur content of 3.78% and a pyritic sulphur content of 2.88%, the rest of sulphur is organic sulphur. The biodesulphurisation process in pilot plant follows three stages: stabilization of the pile, biodesulphurisation and washing. Heap was sampled twice during stabilisation stage, at the end of desulphurisation process and finally once washed. A pyritic sulphur removal of 39% and total sulphur removal of 23% was obtained. To complete the bioleaching process, the treatment of purge of leachate was carried out with the objective to recycling to head of process. The best treatment was a pre-treatment of the leachate until pH 4, and further treatment by reverse osmosis of the clarified water. Comparing this process with conventional precipitation to reach disposal limits, the reagents consumption and sludges were reduced considerably and due to the high quality of permeate it permits to recycle it to head of process. 18 refs., 6 figs., 6 tabs.

  6. Influence of heterotrophic microbial growth on biological oxidation of pyrite

    Energy Technology Data Exchange (ETDEWEB)

    Marchand, E.A.; Silverstein, J. [University of Nevada, Reno, NV (United States). Dept. of Civil Engineering

    2002-12-15

    Experiments were carried out to examine the possibility that enhanced growth of heterotrophic (non-iron-oxidising) bacteria would inhibit pyrite oxidation by Acidithiobacillus ferroxidans by out-competing the more slowly growing autotrophs for oxygen, nutrients or even attachment sites on the mineral surface. Glucose was added to microcosms containing pyrite, acidic mineral solution and cultures of A-ferrooxidans and Acidiphilium acidophilus under various experimental conditions. Results suggest that encouraging the growth of heterotrophic microorganisms under acid mine drainage conditions may be a feasible strategy for decreasing both the rate and the extent of sulfide mineral oxidation. 43 refs., 8 figs., 3 tabs.

  7. Causes of coal degradation at working faces

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, W

    1985-01-01

    Coal comminution by shearer loaders at working faces and factors influencing it are analyzed. Three groups of factors are evaluated: coal mechanical properties, design and specifications of shearer loaders and mining schemes. On the basis of analyses, recommendations for increasing proportion of coarse coal and reducing coal comminution in underground coal mines in Poland are made. Increasing output of coarse coal in coal seams with a high proportion of dull coal is most economic. Increasing power of drive systems for shearer loaders to 500 kW or more decisively influences grain size distribution of coal and increases proportion of coarse coal, especially in seams of dull coal. Gradually increasing cutting depth of a shearer loader negatively influences haulage speed and coarse coal output. Replacing gradual cutting depth increase by attack at the full cutting depth increases proportion of coarse coal. When medium or thick coal seams are mined a coal bench from 0.3 to 0.5 m thick should be left in the roof or between 2 benches cut by 2 cutting drums. The coal bench left in the face disintegrates under the influence of gravity and the proportion of coarse coal increases. Optimizing yield strength of powered supports at a working face is a further method for improving grain size distribution of coal and increasing proportion of coarse coal. 2 references.

  8. New coal

    Energy Technology Data Exchange (ETDEWEB)

    1979-07-01

    Specially dedicated to coal, this edition comprises a series of articles of general interest dealing with the position of the French coalmining industry (interview with M.P. Gardent), the coal market in France, the work of CERCHAR, etc. New techniques, in-situ gasification of deep coal, gasification of coal by nuclear methods, the conversion of coal into petrol, the Emile Huchet power plant of Houilleres du Bassin de Lorraine, etc., are dealt with.

  9. Coal upgrading

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, S. [IEA Clean Coal Centre, London (United Kingdom)

    2009-10-15

    This report examines current technologies and those likely to be used to produce cleaner coal and coal products, principally for use in power generation and metallurgical applications. Consideration is also given to coal production in the leading coal producing countries, both with developed and developing industries. A range of technologies are considered. These include the coal-based liquid fuel called coal water mixture (CWM) that may compete with diesel, the production of ultra-clean coal (UCC) and coal liquefaction which competes with oil and its products. Technologies for upgrading coal are considered, especially for low rank coals (LRC), since these have the potential to fill the gap generated by the increasing demand for coal that cannot be met by higher quality coals. Potential advantages and downsides of coal upgrading are outlined. Taking into account the environmental benefits of reduced pollution achieved through cleaner coal and reduced transport costs, as well as other positive aspects such as a predictable product leading to better boiler design, the advantages appear to be significant. The drying of low rank coals improves the energy productively released during combustion and may also be used as an adjunct or as part of other coal processing procedures. Coal washing technologies vary in different countries and the implications of this are outlined. Dry separation technologies, such as dry jigging and electrostatic separation, are also described. The demonstration of new technologies is key to their further development and demonstrations of various clean coal technologies are considered. A number of approaches to briquetting and pelletising are available and their use varies from country to country. Finally, developments in upgrading low rank coals are described in the leading coal producing countries. This is an area that is developing rapidly and in which there are significant corporate and state players. 81 refs., 32 figs., 3 tabs.

  10. Gasifier feed: Tailor-made from Illinois coals

    Energy Technology Data Exchange (ETDEWEB)

    Ehrlinger, H.P. III.

    1991-01-01

    The purpose of this research is to develop a coal slurry from waste streams using Illinois coal that is ideally suited for a gasification feed. The principle items to be studied are (1) methods of concentrating pyrite and decreasing other ash forming minerals into a high grade gasification feed using froth flotation and gravity separation techniques; (2) chemical and particle size analyses of coal slurries; (3) determination of how that slurry can be densified and to what degree of densification is optimum from the pumpability and combustibility analyses; and (4) reactivity studies.

  11. Sulfur isotope evidence for the contemporary formation of pyrite in a coastal acid sulfate soil

    International Nuclear Information System (INIS)

    Bush, R.T.; Sullivan, L.A.; Prince, K.; White, I.

    2000-01-01

    The sulfur isotopic composition of pyrite (FeS 2 ), greigite (Fe 3 S 4 ) and pore-water sulfate was determined for a typical coastal acid sulfate soil (ASS). Greigite occurs only in the partially oxidised upper-most pyrite sediments as blackish clusters within vertical fissures and other macro-pores. The concentration of pyrite was an order of magnitude greater than greigite in this layer, continuing through the underlying reduced estuarine sediments. δ 34 S of pyrite (0.45 per mil) associated with greigite accumulations were distinctly different to the bulk average for pyrite (-3.7 per mil), but similar to greigite (0.9 per mil). Greigite is meta-stable under reducing conditions, readily transforming to pyrite. The transformation of iron monosulfides (including greigite) to pyrite is a sulfur-isotope conservative process and therefore, these observations indicate that pyrite is forming from greigite at the oxic/anoxic boundary

  12. Mineralogical and geochemical characterization of the Jurassic coal from Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Baioumy, H.M. [Central Metallurgical Research and Development Institute, Cairo (Egypt)

    2009-06-15

    The Jurassic coal deposit in the Maghara area, Sinai, Egypt contains at least 11 coal seams of lenticular shape. The thickness of the main coal seams ranges from 130 cm to 2 m and are underlain and overlain by thin black shale beds. Mineralogical analysis indicated that this coal is characterized by low mineral matter with traces of quartz in some samples. However, coal ash is made up of quartz with traces of calcite, anhydrite, and hematite. Analysis of coal rank parameters indicated that the Maghara coal can be classified as medium volatile bituminous coal. The high sulfur contents and the relatively high proportion of pyritic sulfur suggest a possible marine transgression after the deposition of precursor peat. This interpretation is supported by the relatively high B contents. The relatively high Ge in the Maghara coal could be attributed to an infiltration of Ge enriched water from the surrounding siliceous sediments probably during diagenesis. The high Au contents were contributed to an Au-rich provenance of the ash contents of this coal. Rare earth elements geochemistry indicated low concentrations of these elements with slight enrichment of light rare earth elements (LREEs), slight negative Eu anomaly, and relatively flat heavy rare earth elements (HREEs) patterns. The low contents of trace and rare earth elements, particularly those with environmental relevance, compared to the usual concentration ranges in worldwide coal gives an advantage for this coal.

  13. Use of stable sulphur isotopes to monitor directly the behaviour of sulphur in coal during thermal desulphurization

    Science.gov (United States)

    Liu, Chao-Li; Hackley, Keith C.; Coleman, D.D.

    1987-01-01

    A method has been developed using stable sulphur isotope analyses to monitor the behaviour of sulphur forms in a coal during thermal desulphurization. In this method, the natural stable isotopic composition of the pyritic and organic sulphur in coal is used as a tracer to follow their mobility during the desulphurization process. This tracer method is based on the fact that the isotopic compositions of pyritic and organic sulphur are significantly different in some coals. Isotopic results of pyrolysis experiments at temperatures ranging from 350 to 750 ??C indicate that the sulphur released with the volatiles is predominantly organic sulphur. The pyritic sulphur is evolved in significant quantities only when pyrolysis temperatures exceed 500 ??C. The presence of pyrite seems to have no effect on the amount of organic sulphur evolved during pyrolysis. The chemical and isotopic mass balances achieved from three different samples of the Herrin (No. 6) coal of the Illinois Basin demonstrate that this stable isotope tracer method is quantitative. The main disadvantage of this tracing technique is that not all coals contain isotopically distinct organic and pyritic sulphur. ?? 1987.

  14. A model of pyritic oxidation in waste rock dumps

    International Nuclear Information System (INIS)

    Davis, G.B.; Ritchie, A.I.M.

    1983-01-01

    The oxidation of pyrite can lead to high acid levels and high concentrations of trace metals in the water that runs off and percolates through pyritic material. This is the situation at the abandoned uranium mine at Rum Jungle in the Northern Territory of Australia, where pyritic oxidation in the waste rock dumps resulting from open cut mining of the uranium orebody has led to pollution of the nearby East Branch of the Finniss River, with trace metals such as copper, manganese and zinc. Mathematical equations are formulated which describe a model of pyritic oxidation within a waste rock dump, where it is assumed that oxygen transport is the rate limiting step in the oxidation process and that oxygen is transported by gaseous diffusion through the pore space of the dump, followed by diffusion into oxidation sites within the particles that comprise the dump. The equations have been solved numerically assuming values for such parameters as porosity, sulphur density and oxygen diffusion coefficients which are applicable to the waste rock dumps at Rum Jungle. An approximate solution to the equations is also presented. Calculations of the heat source distribution and the total SO 4 production rate are presented for both single size particles and for a range of particle sizes in the dump. The usefulness of the approximate solution, and of calculations based on single size particles in the dump in assessing the effectiveness of strategies to reduce pollution from such waste rock dumps are discussed

  15. Modelling the reactive-path between pyrite and radioactive nuclides

    International Nuclear Information System (INIS)

    Kang Mingliang; Wu Shijun; Dou Shunmei; Chen Fanrong; Yang Yongqiang

    2008-01-01

    The mobility of redox sensitive nuclides is largely dependent on their valence state. The radionuclides that make the dominant contributions to final dose calculations are redox sensitive. Almost all the radionuclides (except 129 I) have higher mobility at high valence state, and correspond to immobilization at low valence state due to the much lower solubility. Pyrite is an ubiquitous and stable mineral in geological environment, and would be used as a low-cost long time reductant for the immobilization of radionuclides. However, pyrite oxidation is supposed to generate acid, which will enhance the mobility of nuclides. In this paper, the reaction path of the reactions between radionuclides (U, Se and Tc) and pyrite in the groundwater from Wuyi well in Beishan area of China has been simulated using geochemical modeling software. According to the results, pyrite can reduce high valence nuclides to a dinky-level effectively, with the pH slightly increasing under anaerobic condition that is common in deep nuclear waste repositories. (authors)

  16. Using X-ray methods to evaluate the combustion sulfur minerals and graphitic carbon in coals and ashes

    International Nuclear Information System (INIS)

    Wertz, D.L.; Collins, L.W.

    1988-01-01

    Coals are complex mixtures of vastly different materials whose combustion kinetics may well exhibit symbiotic effects. Although the sulfur oxide gases produced during the combustion of coals may have a variety of sources, they are frequently caused by the thermal degradation of inorganic minerals to produce ''acid rain''. Since many of the minerals involved either as reactants or products in coal combustion produce well defined x-ray power diffraction (XRPD) patterns, the fate of these minerals may be followed by measuring the XRPD patterns of combustion products. Coal 1368P, a coal with an unusually high pyrite (FeS/sub 2/) fraction, has been the subject materials in our investigations of the fate of the inorganic minerals during combustion. These studies include measuring the fate of pyrite and of graphitic carbon in coal 1368P under varying combustion conditions. The results discussed in this paper were obtained by standard XRPD methods

  17. Coal-92

    International Nuclear Information System (INIS)

    Hillring, B.; Sparre, C.

    1992-11-01

    Swedish consumption of coal and coke during 1991 and trends in technology, environment and market aspects of coal use are reported. Steam coal use in the heating sector was unchanged from 1991, 1.2 Mtons. Reduced consumption in smaller district heating units (due to conversion to biofuels and gas) was compensated by increased use for power generation in cogeneration plants. Coal consumption in industry fell 0.10 Mton to 0.84 Mton due to lower production in one industry branch. Import of steam coal was 1.1 Mton (down 0.5 Mton from 1990) since new rules for strategic reserves allowed a reduction of stocks. During the last five years stocks have been reduced by 2 Mtons. Import of metallurgical coal was 1.6 Mton, unchanged from 1990. The report also gives statistics for the coal using plants in Sweden, on coal R and D, and on emission laws for coal firing. (9 tabs., 2 figs.)

  18. Special requirements for the fluid mechanical design of hard coal-fired SCR retrofit units

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The system design of high-dust SCR units for retrofits is a challenge that is to be mastered in order to meet the fluid mechanical requirements. Retrofitting power plants with NOx control technologies is a cost-intensive adventure that many utilities are undertaking. Except for a few recent new boiler installations, SCR installations must be considered as retrofit projects. In most cases the limitation of space on site entails unfavorable conditions that do not allow appropriate upstream conditions for SCR catalysts. To comply with the requirements of high performance DeNOx systems and to lower the investment costs for retrofit units, several technical solutions and concepts for the reactor layout, for NOx and dust distribution, for flow stabilization in diffusers, and advanced ammonia injection systems are explained in this paper. Balcke-Duerr offers customer-tailored solutions for flow optimization, which are evaluated by model studies. Physical flow and dust model tests in an appropriate scale provide flexibility to test various engineering concepts. The experience of Balcke-Duerr is based on continuous research and development activities over the last 25 years and more than 350 executed projects for gas flow optimization applications. The success of these installations is a direct result of the key decisions based on the improved fluid mechanical design and proper system integration. This paper also identifies the sensible design particularities and solutions that have two be considered in the fluid mechanical design of high-dust SCR retrofit units. This article demonstrates that the layout of SCR units must be carefully reviewed in order to meet the performance requirements and to avoid problems, i.e. wear, catalyst plugging and ammonia slip. 9 refs., 18 figs.

  19. The mechanism of coking pressure generation II: Effect of high volatile matter coking coal, semi-anthracite and coke breeze on coking pressure and contraction

    Energy Technology Data Exchange (ETDEWEB)

    Merrick Mahoney; Seiji Nomura; Koichi Fukuda; Kenji Kato; Anthony Le Bas; David R. Jenkins; Sid McGuire [BHP Billiton Technology, Shortland, NSW (Australia)

    2010-07-15

    One of the most important aspects of the cokemaking process is to control and limit the coking pressure since excessive coking pressure can lead to operational problems and oven wall damage. Following on from a previous paper on plastic layer permeability we have studied the effect of contraction of semi-coke on coking pressure and the effect of organic additives on contraction. A link between contraction (or simulated contraction) outside the plastic layer and coking pressure was demonstrated. The interaction between this contraction, local bulk density around the plastic layer and the dependence of the permeability of the plastic layer on bulk density was discussed as possible mechanisms for the generation of coking pressure. The effect of blending either a high volatile matter coal or one of two semi-anthracites with low volatile matter, high coking pressure coals on the coking pressure of the binary blends has been explained using this mechanism. 25 refs., 10 figs., 4 tabs.

  20. Pyrite sulfur isotopes reveal glacial-interglacial environmental changes

    Science.gov (United States)

    Pasquier, Virgil; Sansjofre, Pierre; Rabineau, Marina; Revillon, Sidonie; Houghton, Jennifer; Fike, David A.

    2017-06-01

    The sulfur biogeochemical cycle plays a key role in regulating Earth’s surface redox through diverse abiotic and biological reactions that have distinctive stable isotopic fractionations. As such, variations in the sulfur isotopic composition (δ34S) of sedimentary sulfate and sulfide phases over Earth history can be used to infer substantive changes to the Earth’s surface environment, including the rise of atmospheric oxygen. Such inferences assume that individual δ34S records reflect temporal changes in the global sulfur cycle; this assumption may be well grounded for sulfate-bearing minerals but is less well established for pyrite-based records. Here, we investigate alternative controls on the sedimentary sulfur isotopic composition of marine pyrite by examining a 300-m drill core of Mediterranean sediments deposited over the past 500,000 y and spanning the last five glacial-interglacial periods. Because this interval is far shorter than the residence time of marine sulfate, any change in the sulfur isotopic record preserved in pyrite (δ34Spyr) necessarily corresponds to local environmental changes. The stratigraphic variations (>76‰) in the isotopic data reported here are among the largest ever observed in pyrite, and are in phase with glacial-interglacial sea level and temperature changes. In this case, the dominant control appears to be glacial-interglacial variations in sedimentation rates. These results suggest that there exist important but previously overlooked depositional controls on sedimentary sulfur isotope records, especially associated with intervals of substantial sea level change. This work provides an important perspective on the origin of variability in such records and suggests meaningful paleoenvironmental information can be derived from pyrite δ34S records.

  1. Investigation of virgin coals and coals subjected to a mild acid treatment

    Energy Technology Data Exchange (ETDEWEB)

    Clark, T.M.; Evans, B.J.; Wynter, C.; Pollak, H.; Taole, S.; Radcliffe, D. [University of Michigan, Ann Arbor, MI (United States). Dept. of Chemistry

    1998-06-01

    A quantitative determination of the relative marcasite/pyrite contents in virgin coals is possible by means of {sup 57}Fe Moessbauer spectroscopy. Complications arise however, when iron-containing silicates, carbonates, or other salts are present. The application of a mild chemical treatment involving hydrofluoric acid has been employed to remove these Fe-containing phases while leaving the iron-disulfide phases unaffected. Several South African coal samples with non-iron disulfide, Fe-containing phases ranging from 18 to 30 weight percent were subjected to a hydrofluoric acid leaching at room temperature. The loss of mineral matter with HF leaching correlates well with the mineral matter residue following low temperature ashing. The {sup 57}Fe Moessbauer spectra of the resulting coal samples indicate that only FeS{sub 2} phases are present and the absence of appreciable quantities of marcasite in the coals.

  2. Methane of the coal

    International Nuclear Information System (INIS)

    Vasquez, H.

    1997-01-01

    In the transformation process of the vegetable material to the coal (Carbonization), the products that are generated include CH 4, CO2, N2 and H2. The methane is generated by two mechanisms: below 50 centigrade degree, as product of microbial decomposition, the methanogenic is generated; and above 50 centigrade degree, due to the effects of the buried and increase of the range of the coal, the thermogenic methane is detachment, as a result of the catagenic. The generated methane is stored in the internal surfaces of the coal, macro and micro pores and in the natural fractures. The presence of accumulations of gas of the coal has been known in the entire world by many years, but only as something undesirable for its danger in the mining exploitation of the coal

  3. A high-pyrite semianthracite of Late Permian age in the Songzao Coalfield, southwestern China: Mineralogical and geochemical relations with underlying mafic tuffs

    Science.gov (United States)

    Dai, S.; Wang, X.; Chen, W.; Li, D.; Chou, C.-L.; Zhou, Y.; Zhu, Chen; Li, H.; Zhu, Xudong; Xing, Y.; Zhang, W.; Zou, J.

    2010-01-01

    The No. 12 Coal (Late Permian) in the Songzao Coalfield, Chongqing, southwestern China, is characteristically high in pyrite and some trace elements. It is uniquely deposited directly above mafic tuff beds. Samples of coal and tuffs have been studied for their mineralogy and geochemistry using inductively coupled plasma-mass spectrometry, X-ray fluorescence, plasma low-temperature ashing plus powder X-ray diffraction, and scanning electron microscopy equipped with energy-dispersive X-ray analysis.The results show that the minerals of the No. 12 Coal are mainly composed of pyrite, clay minerals (kaolinite, chamosite, and illite), ankerite, calcite, and trace amounts of quartz and boehmite. Kaolinite and boehmite were mainly derived from sediment source region of mafic tuffs. Chamosite was formed by the reaction of kaolinite with Fe-Mg-rich fluids during early diagenesis. The high pyrite (Sp,d=8.83%) in the coal was related to marine transgression over peat deposits and abundant Fe derived from the underlying mafic tuff bed. Ankerite and calcite were precipitated from epigenetic fluids.Chemical compositions of incompatible elements indicate that the tuffs were derived from enriched mantle and the source magmas had an alkali-basalt character. Compared to other coals from the Songzao Coalfield and common Chinese coals, the No. 12 Coal has a lower SiO2/Al2O3 (1.13) but a higher Al2O3/Na2O (80.1) value and is significantly enriched in trace elements including Sc (13.5??g/g), V (121??g/g), Cr (33.6??g/g), Co (27.2??g/g), Ni (83.5??g/g), Cu (48.5??g/g), Ga (17.3??g/g), Y (68.3??g/g), Zr (444??g/g), Nb (23.8??g/g), and REE (392??g/g on average). Above mineralogical compositions, as well as similar ratios of selected elements (e.g., SiO2/Al2O3 and Al2O3/Na2O) and similar distribution patterns of incompatible elements (e.g., the mantle-normalized diagram for incompatible elements and chondrite-normalized diagram for rare earth elements) of coal and tuff, indicated that

  4. A high-pyrite semianthracite of Late Permian age in the Songzao Coalfield, southwestern China: Mineralogical and geochemical relations with underlying mafic tuffs

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Shifeng; Wang, Xibo; Chen, Wenmei [State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing 100083, (China); Li, Dahua [Research Center of State Key Laboratory of Coal Resources and Safe Mining, Chongqing 400042, (China); Chou, Chen-Lin [Illinois State Geological Survey (Emeritus), 615 East Peabody Drive, Champaign, IL 61820, (United States); Zhou, Yiping [Yunnan Institute of Coal Geology Prospection, Kunming 650218, (China); Zhu, Changsheng; Li, Hang [Research Center of State Key Laboratory of Coal Resources and Safe Mining, Chongqing 400042, (China); Zhu, Xingwei; Xing, Yunwei; Zhang, Weiguo; Zou, Jianhua [State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing 100083, (China)

    2010-09-01

    The No. 12 Coal (Late Permian) in the Songzao Coalfield, Chongqing, southwestern China, is characteristically high in pyrite and some trace elements. It is uniquely deposited directly above mafic tuff beds. Samples of coal and tuffs have been studied for their mineralogy and geochemistry using inductively coupled plasma-mass spectrometry, X-ray fluorescence, plasma low-temperature ashing plus powder X-ray diffraction, and scanning electron microscopy equipped with energy-dispersive X-ray analysis. The results show that the minerals of the No. 12 Coal are mainly composed of pyrite, clay minerals (kaolinite, chamosite, and illite), ankerite, calcite, and trace amounts of quartz and boehmite. Kaolinite and boehmite were mainly derived from sediment source region of mafic tuffs. Chamosite was formed by the reaction of kaolinite with Fe-Mg-rich fluids during early diagenesis. The high pyrite (S{sub p,d} 8.83%) in the coal was related to marine transgression over peat deposits and abundant Fe derived from the underlying mafic tuff bed. Ankerite and calcite were precipitated from epigenetic fluids. Chemical compositions of incompatible elements indicate that the tuffs were derived from enriched mantle and the source magmas had an alkali-basalt character. Compared to other coals from the Songzao Coalfield and common Chinese coals, the No. 12 Coal has a lower SiO{sub 2}/Al{sub 2}O{sub 3} (1.13) but a higher Al{sub 2}O{sub 3}/Na{sub 2}O (80.1) value and is significantly enriched in trace elements including Sc (13.5 {mu}g/g), V (121 {mu}g/g), Cr (33.6 {mu}g/g), Co (27.2 {mu}g/g), Ni (83.5 {mu}g/g), Cu (48.5 {mu}g/g), Ga (17.3 {mu}g/g), Y (68.3 {mu}g/g), Zr (444 {mu}g/g), Nb (23.8 {mu}g/g), and REE (392 {mu}g/g on average). Above mineralogical compositions, as well as similar ratios of selected elements (e.g., SiO{sub 2}/Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/Na{sub 2}O) and similar distribution patterns of incompatible elements (e.g., the mantle-normalized diagram for

  5. Coal 1992

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    ACR's Coal 1992, the successor to the ACR Coal Marketing Manual, contains a comprehensive set of data on many aspects of the Australian coal industry for several years leading up to 1992. Tables and text give details of coal production and consumption in New South Wales, Queensland and other states. Statistics of the Australian export industry are complemented by those of South Africa, USA, New Zealand, Canada, Indonesia, China, Colombia, Poland and ex-USSR. Also listed are prices of Australian coking and non-coking coal, Australian coal stocks (and those of other major countries), loading port capacities, freight rates and coal quality requirements (analysis of coals by brand and supplier). A listing of Australian coal exporting companies is provided. A description of the spot Coal Screen Dealing System is given. World hard coal imports are listed by country and coal imports by major Asian countries tabulated. A forecast of demand by coal type and country up to the year 2000 is included.

  6. Distribution and mode of occurrence of selenium in US coals

    Science.gov (United States)

    Coleman, L.; Bragg, L.J.; Finkelman, R.B.

    1993-01-01

    Selenium excess and deficiency have been established as the cause of various health problems in man and animals. Combustion of fossil fuels, especially coal, may be a major source of the anthropogenic introduction of selenium in the environment. Coal is enriched in selenium relative to selenium's concentration in most other rocks and relative to selenium in the Earth's crust. Data from almost 9,000 coal samples have been used to determine the concentration and distribution of selenium in US coals. The geometric mean concentration of selenium in US coal is 1.7 ppm. The highest mean selenium value (geometric mean 4.7 ppm) is in the Texas Region. Atlantic Coast (Virginia and North Carolina) and Alaska coals have the lowest geometric means (0.2 and 0.42 ppm, respectively). All western coal regions have mean selenium concentrations of less than 2.0 ppm. In contrast, all coal basins east of the Rocky Mountains (except for several small basins in Rhode Island, Virginia, and North Carolina) have mean selenium values of 1.9 or greater. Generally, variations in selenium concentration do not correlate with variations in ash yield, pyritic sulphur, or organic sulphur concentrations. This may be the result of multiple sources of selenium; however, in some non-marine basins with restricted sources of selenium, selenium has positive correlations with other coal quality parameters. Selenium occurs in several forms in coal but appears to be chiefly associated with the organic fraction, probably substituting for organic sulphur. Other important forms of selenium in coal are selenium-bearing pyrite, selenium-bearing galena, and lead selenide (clausthalite). Water-soluble and ion-exchangeable selenium also have been reported. ?? 1993 Copyright Science and Technology Letters.

  7. Coal pump

    Science.gov (United States)

    Bonin, John H.; Meyer, John W.; Daniel, Jr., Arnold D.

    1983-01-01

    A device for pressurizing pulverized coal and circulating a carrier gas is disclosed. This device has utility in a coal gasification process and eliminates the need for a separate collection hopper and eliminates the separate compressor.

  8. The composition of pyrite in volcanogenic massive sulfide deposits as determined with the proton microprobe

    International Nuclear Information System (INIS)

    Huston, D.L.; Sie, S.H.; Suter, G.F.; Ryan, C.G.

    1993-01-01

    Pixeprobe analysis of pyrite from Australian volcanogenic massive sulfide (VMS) deposits indicate significant levels of Cu, Zn, Pb, Ba, Ag, Sb, Bi (from inclusions), As, Tl, Mo, Au, In, Cd (from nonstoichiometric substitution), Co, Ni, Se and Te (from stoichiometric substitution). Pyrite in massive sulfide lenses is enriched in trace elements compared to that in the stringer zone owing to hydrothermal recrystallization. Metamorphic recrystallization also 'cleans' pyrite of trace elements. High Au values occur in pyrite with high As content. Pyrite in stringer zones is enriched in Se relative to the overlying massive sulfide lenses and the surrounding alteration zones. (orig.)

  9. Bioprocessing of lignite coals using reductive microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, D.L.

    1992-03-29

    In order to convert lignite coals into liquid fuels, gases or chemical feedstock, the macromolecular structure of the coal must be broken down into low molecular weight fractions prior to further modification. Our research focused on this aspect of coal bioprocessing. We isolated, characterized and studied the lignite coal-depolymerizing organisms Streptomyces viridosporus T7A, Pseudomonas sp. DLC-62, unidentified bacterial strain DLC-BB2 and Gram-positive Bacillus megaterium strain DLC-21. In this research we showed that these bacteria are able to solubilize and depolymerize lignite coals using a combination of biological mechanisms including the excretion of coal solublizing basic chemical metabolites and extracellular coal depolymerizing enzymes.

  10. Trace metal pyritization variability in response to mangrove soil aerobic and anaerobic oxidation processes.

    Science.gov (United States)

    Machado, W; Borrelli, N L; Ferreira, T O; Marques, A G B; Osterrieth, M; Guizan, C

    2014-02-15

    The degree of iron pyritization (DOP) and degree of trace metal pyritization (DTMP) were evaluated in mangrove soil profiles from an estuarine area located in Rio de Janeiro (SE Brazil). The soil pH was negatively correlated with redox potential (Eh) and positively correlated with DOP and DTMP of some elements (Mn, Cu and Pb), suggesting that pyrite oxidation generated acidity and can affect the importance of pyrite as a trace metal-binding phase, mainly in response to spatial variability in tidal flooding. Besides these aerobic oxidation effects, results from a sequential extraction analyses of reactive phases evidenced that Mn oxidized phase consumption in reaction with pyrite can be also important to determine the pyritization of trace elements. Cumulative effects of these aerobic and anaerobic oxidation processes were evidenced as factors affecting the capacity of mangrove soils to act as a sink for trace metals through pyritization processes. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Source of arsenic-bearing pyrite in southwestern Vermont, USA: Sulfur isotope evidence

    Energy Technology Data Exchange (ETDEWEB)

    Mango, Helen, E-mail: helen.mango@castleton.edu [Department of Natural Sciences, Castleton State College, 233 South Street, Castleton, VT 05735 (United States); Ryan, Peter, E-mail: pryan@middlebury.edu [Department of Geology, Middlebury College, 276 Bicentennial Way, Middlebury, VT 05753 (United States)

    2015-02-01

    Arsenic-bearing pyrite is the source of arsenic in groundwater produced in late Cambrian and Ordovician gray and black slates and phyllites in the Taconic region of southwestern Vermont, USA. The aim of this study is to analyze the sulfur isotopic composition of this pyrite and determine if a relationship exists between pyrite δ{sup 34}S and arsenic content. Pyrite occurs in both sedimentary/diagenetic (bedding-parallel layers and framboids) and low-grade metamorphic (porphyroblast) forms, and contains up to > 2000 ppm As. The sulfur isotopic composition of arsenic-bearing pyrite ranges from − 5.2‰ to 63‰. In the marine environment, the sulfur in sedimentary pyrite becomes increasingly enriched in {sup 34}S as the geochemical environment becomes increasingly anoxic. There is a positive correlation between δ{sup 34}S and arsenic content in the Taconic pyrite, suggesting that uptake of arsenic by pyrite increased as the environment became more reducing. This increased anoxia may have been due to a rise in sea level and/or tectonic activity during the late Cambrian and Ordovician. Low-grade metamorphism appears to have little effect on sulfur isotope composition, but does correlate with lower arsenic content in pyrite. New groundwater wells drilled in this region should therefore avoid gray and black slates and phyllites that contain sedimentary/diagenetic pyrite with heavy δ{sup 34}S values. - Highlights: • Pyrite is the source of arsenic in groundwater in the Taconic region of Vermont, USA. • As-bearing pyrite δ{sup 34}S = – 5.2 to 63‰ with higher {sup 34}S as environment becomes more anoxic. • High sea level, tectonic activity create anoxia, with incorporation of As into pyrite. • New wells should avoid slate/phyllite containing sedimentary pyrite with heavy δ{sup 34}S.

  12. Source of arsenic-bearing pyrite in southwestern Vermont, USA: Sulfur isotope evidence

    International Nuclear Information System (INIS)

    Mango, Helen; Ryan, Peter

    2015-01-01

    Arsenic-bearing pyrite is the source of arsenic in groundwater produced in late Cambrian and Ordovician gray and black slates and phyllites in the Taconic region of southwestern Vermont, USA. The aim of this study is to analyze the sulfur isotopic composition of this pyrite and determine if a relationship exists between pyrite δ 34 S and arsenic content. Pyrite occurs in both sedimentary/diagenetic (bedding-parallel layers and framboids) and low-grade metamorphic (porphyroblast) forms, and contains up to > 2000 ppm As. The sulfur isotopic composition of arsenic-bearing pyrite ranges from − 5.2‰ to 63‰. In the marine environment, the sulfur in sedimentary pyrite becomes increasingly enriched in 34 S as the geochemical environment becomes increasingly anoxic. There is a positive correlation between δ 34 S and arsenic content in the Taconic pyrite, suggesting that uptake of arsenic by pyrite increased as the environment became more reducing. This increased anoxia may have been due to a rise in sea level and/or tectonic activity during the late Cambrian and Ordovician. Low-grade metamorphism appears to have little effect on sulfur isotope composition, but does correlate with lower arsenic content in pyrite. New groundwater wells drilled in this region should therefore avoid gray and black slates and phyllites that contain sedimentary/diagenetic pyrite with heavy δ 34 S values. - Highlights: • Pyrite is the source of arsenic in groundwater in the Taconic region of Vermont, USA. • As-bearing pyrite δ 34 S = – 5.2 to 63‰ with higher 34 S as environment becomes more anoxic. • High sea level, tectonic activity create anoxia, with incorporation of As into pyrite. • New wells should avoid slate/phyllite containing sedimentary pyrite with heavy δ 34 S

  13. Biochemical removal of HAP precursors from coal. Quarterly technical progress report, April--June 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    Analytical methods were finalized and all analyses completed on shake flask tests with Indiana No. 5 and Pittsburgh No. 8 coal. A column leaching-rotating biological contractor (RBC) unit was used to bioleach pyrite and hazardous air pollutant precursors from Pittsburgh No. 8 coal. Shake flask tests with Rosebud subbituminous coal were begun. In connection with upcoming slurry column reactor tests, coal was prepared and shipped to INEL, and a detailed work plan was developed for operation and sampling for the tests. A manuscript and poster was prepared for presentation at the PETC contractors conference.

  14. Effect of mixes made of coal bottom ash and fly ash on the mechanical strength and porosity of Portland cement

    Directory of Open Access Journals (Sweden)

    Argiz, C.

    2013-03-01

    Full Text Available New additions to the cement are needed to achieve a more sustainable and durable construction material. Within this context, bottom ashes can be used as a main constituent of Portland cements when it is mixed in an optimized proportion with fly ashes. The mechanical characteristics of standarized mortars made of mixes of pulverized coal combustion bottom and fly ashes are studied. The mortars were made of ordinary Portland cement (CEM I 42.5 N and mixes of bottom ashes with fly ashes in similar proportions to those of CEM II/A-V, CEM II/B-V and CEM IV/A (V. Summing up, it can be said that the utilization of bottom ashes mixed with fly ashes in replacement levels from 0% to 100% do not affect significantively on the mechanical caracteristics of the mortars considered in the present study which had an addition maximum content of 35%.

    La utilización de nuevas adiciones en el cemento es necesaria con el fin de obtener un material más sostenible y durable. En este sentido, las cenizas de fondo o cenicero de las centrales termoeléctricas de carbón se podrían reciclar siendo empleadas como un componente principal de los cementos Portland. Se han estudiado las propiedades mecánicas de unos morteros normalizados elaborados con mezclas de cenizas volantes con cenizas de fondo fabricados con unos porcentajes similares a los correspondientes de los CEM II/A-V, CEM II/B-V y CEM IV/A (V. En conclusión, la utilización de mezclas de cenizas de fondo o cenicero con cenizas volantes sustituyendo a éstas últimas entre el 0% y el 100%, no influye significativamente en el comportamiento mecánico de los morteros estudiados en los que el contenido máximo de adición ha sido del 35%, si bien afecta a determinados aspectos microestructurales, como la cantidad y distribución de poros capilares.

  15. Production of pyrite nanoparticles using high energy planetary ball milling for sonocatalytic degradation of sulfasalazine.

    Science.gov (United States)

    Khataee, Alireza; Fathinia, Siavash; Fathinia, Mehrangiz

    2017-01-01

    Sonocatalytic performance of pyrite nanoparticles was evaluated by the degradation of sulfasalazine (SSZ). Pyrite nanoparticles were produced via a high energy mechanical ball milling (MBM) in different processing time from 2h to 6h, in the constant milling speed of 320rpm. X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR) analysis and Brunauer-Emmett-Teller (BET) confirmed the production of pyrite nanoparticles during 6h of ball milling with the average size distribution of 20-80nm. The effects of various operational parameters including pH value, catalyst amount (mg/L), SSZ concentration (mg/L), ultrasonic frequency (kHz) and reaction time on the SSZ removal efficiency were examined. The obtained results showed that the maximum removal efficiency of 97.00% was obtained at pH value of 4, catalyst dosage of 0.5g/L, SSZ concentration of 10mg/L and reaction time of 30min. Experimental results demonstrated that the kinetic of the degradation process can be demonstrated using Langmuir-Hinshelwood (L-H) kinetic model. The effect of different inorganic ions such as Cl - , CO 3 2- and SO 4 2- was investigated on the L-H reaction rate (k r ) and adsorption (K s ) constants. Results showed that the presence of the mentioned ions significantly influenced the L-H constants. The impact of ethanol as a OH radical scavenger and some enhancers including H 2 O 2 and K 2 S 2 O 8 was investigated on the SSZ removal efficiency. Accordingly, the presence of ethanol suppressed SSZ degradation due to the quenching of OH radicals and the addition of K 2 S 2 O 8 and H 2 O 2 increased the SSZ removal efficiency, due to the formation of SO 4 - and additional OH radicals, respectively. Under the identical conditions of operating parameters, pyrite nanoparticles maintained their catalytic activity during four consecutive runs. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Abiotic pyrite reactivity versus nitrate, selenate and selenite using chemical and electrochemical methods

    International Nuclear Information System (INIS)

    Ignatiadis, I.; Betelu, S.; Gaucher, E.; Tournassat, C.; Chainet, F.

    2010-01-01

    Document available in extended abstract form only. This work is part of ReCosy European project (www.recosy.eu), whose main objectives are the sound understanding of redox phenomena controlling the long-term release/retention of radionuclides in nuclear waste disposal and providing tools to apply the results to performance assessment/safety case. Redox is one of the main factor affecting speciation and mobility of redox-sensitive radionuclides. Thus, it is of a great importance to investigate the redox reactivity of the host radioactive waste formations, particularly when exposed to redox perturbations. Callovo-Oxfordian formation (COx), a clay rock known as an anoxic and reducing system, was selected in France as the most suitable location to store nuclear waste. Iron (II) sulfide, mostly constituted of pyrite (FeS 2 ), iron (II) carbonate, iron(II) bearing clays and organic matter are considered to account almost entirely for the total reducing capacity of the rock. We report here the redox reactivity of pyrite upon exposure to nitrate (N(V)), selenate (Se(VI)) and selenite (Se(IV)) that possibly occur in the nuclear storage. Both, chemical and electrochemical kinetic approaches were simultaneously conducted such as to (i) determine the kinetics parameters of the reactions and (ii) understand the kinetic mechanisms. In order to reach similar conditions that are encountered in the storage system, all experiments were realised in NaCl 0.1 M, near neutral pH solutions, and an abiotic glove box (O 2 less than 10 -8 M). Chemical approach has consisted to set in contact pyrite in grains with solutions containing respectively nitrate, selenate and selenite. Reactants and products chemical analyses, conducted at different contact times, allowed us to assess the kinetics of oxidant reduction. Electrochemical approach has consisted in the continuous or semi-continuous analysis of large surface pyrite electrodes immersed in solutions with or without oxidant (nitrate

  17. Lattice location of gold in natural pyrite crystals

    International Nuclear Information System (INIS)

    Besten, Jacinta den; Jamieson, David N.; Ryan, Chris G.

    1999-01-01

    The lattice location of gold atoms in naturally occurring Au-doped pyrite crystals has been investigated with a nuclear microprobe using ion channeling. The specimens consisted of 300-μm diameter pyrite crystals in veins embedded in a quartz matrix from the Emperor mine in Fiji. The specimens were prepared by standard geological specimen preparation techniques and the pyrite crystals were analysed in situ in the quartz matrix. Significant trace elements in the crystals, determined by Proton Induced X-ray Emission with a 3 MeV H + microprobe, were Cu, As, Mo, Zn, Te, Au and Pb. The Au concentration was about 0.2 wt%. By the use of 2 MeV He + ion channeling, the Miller indices of the lowest order crystal axes nearest to the normal were determined from backscattering yield maps from two-dimensional angular scanning and comparison of the resulting patterns with published gnomonic projections. Channeling angular yield curves were obtained from Fe, S, As and Au signals. The results indicate that at least 35% of the Au is substituted onto lattice sites

  18. Heterocoagulation of chalcopyrite and pyrite minerals in flotation separation.

    Science.gov (United States)

    Mitchell, Timothy K; Nguyen, Anh V; Evans, Geoffrey M

    2005-06-30

    Heterocoagulation between various fine mineral particles contained within a mineral suspension with different structural and surface chemistry can interfere with the ability of the flotation processes to selectively separate the minerals involved. This paper examines the interactions between chalcopyrite (a copper mineral) and pyrite (an iron mineral often bearing gold) as they approach each other in suspensions with added chemicals, and relates the results to the experimental data for the flotation recovery and selectivity. The heterocoagulation was experimentally studied using the electrophoretic light scattering (ELS) technique and was modelled by incorporating colloidal forces, including the van der Waals, electrostatic double layer and hydrophobic forces. The ELS results indicated that pyrite has a positive zeta potential (zeta) up to its isoelectric point (IEP) at approximately pH 2.2, while chalcopyrite has a positive zeta up to its IEP at approximately pH 5.5. This produces heterocoagulation of chalcopyrite with pyrite between pH 2.2 and pH 5.5. The heterocoagulation was confirmed by the ELS spectra measured with a ZetaPlus instrument from Brookhaven and by small-scale flotation experiments.

  19. Thermoluminescence kinetics of pyrite (FeS2)

    International Nuclear Information System (INIS)

    Silverman, A.N; Levy, P.W.; Kierstead, J.A.

    1990-01-01

    Thermoluminescence of pyrite (FeS 2 ) has been investigated to study the kinetics of single peak glow curves. The material used normally exhibits one large and four small peaks. However a glow curve can be obtained with only the large single peak that is suitable for testing thermoluminescence kinetics. Glow curves from aliquots of a single natural pyrite crystal studied in detail contain two low intensity thermoluminescence (TL) peaks at ∼90 degree and ∼250 degree C, and two chemiluminescence (CL) peaks at ∼350 degree and ∼430 degree C. The CL peaks are largely removable by initially heating the sample chamber under vacuum, pumping through liquid nitrogen traps, and recording glow curves immediately after helium is introduced, procedures which reduce system contaminants that react with pyrite. The shape, the variation of the temperature of the peak maximum (T max ) with dose, and the retrapping to recombination cross section ratio σ of the large 250 degree C peak are better described by the general one trap (GOT) kinetic equation, the basic equation from which the 1st and 2nd order kinetic equations are obtained as special cases (see text), than by the 1st and 2nd order equations. 12 refs., 7 figs

  20. Self-Scrubbing Coal -- an integrated approach to clean air

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, K.E. [Custom Coals Corp., Pittsburgh, PA (United States)

    1997-12-31

    Carefree Coal is coal cleaned in a proprietary dense-media cyclone circuit, using ultrafine magnetite slurries, to remove noncombustible material, including up to 90% of the pyritic sulfur. Deep cleaning alone, however, cannot produce a compliance fuel from coals with high organic sulfur contents. In these cases, Self-Scrubbing Coal will be produced. Self-Scrubbing Coal is produced in the same manner as Carefree Coal except that the finest fraction of product from the cleaning circuit is mixed with limestone-based additives and briquetted. The reduced ash content of the deeply-cleaned coal will permit the addition of relatively large amounts of sorbent without exceeding boiler ash specifications or overloading electrostatic precipitators. This additive reacts with sulfur dioxide (SO{sub 2}) during combustion of the coal to remove most of the remaining sulfur. Overall, sulfur reductions in the range of 80--90% are achieved. After nearly 5 years of research and development of a proprietary coal cleaning technology coupled with pilot-scale validation studies of this technology and pilot-scale combustion testing of Self-Scrubbing Coal, Custom Coals Corporation organized a team of experts to prepare a proposal in response to DOE`s Round IV Program Opportunity Notice for its Clean Coal Technology Program under Public Law 101-121 and Public Law 101-512. The main objective of the demonstration project is the production of a coal fuel that will result in up to 90% reduction in sulfur emissions from coal-fired boilers at a cost competitive advantage over other technologies designed to accomplish the same sulfur emissions and over naturally occurring low sulfur coals.

  1. Influence of mechanical activation on the synthesis of Sr-Celsian employing a precursor mixture containing coal fly ash

    Directory of Open Access Journals (Sweden)

    López-Badillo, C. M.

    2013-04-01

    Full Text Available Strontium aluminosilicate, SrAl2Si2O8 (SAS, was synthesized by a solid state reaction using coal fly ash (CFA as main raw material. A precursor mixture of SrCO3, CFA and Al2O3 was mechanically-activated for times of up to 12 h using an attrition mill, and subsequently sintered at temperatures of 900-1300 °C. The CFA and the mechanical activation were employed with the aim to promote the transformation from the hexagonal (Sr-Hexacelsian into the monoclinic (Sr-Celsian polymorphic form of SAS, since the latter phase is associated with better physical and mechanical properties but the former tends to be the first one to appear. The mean particle size, the crystallite size and the temperature at the end of the curve of weight loss (Tf decreased, while the specific surface area and the degree of amorphization increased, with increasing milling time. Samples milled for at least 4 h and then sintered at 1100 °C achieved full transformation into Sr-Celsian. The same result was obtained for sintering temperatures higher than 1100 °C, independently of milling time. An increment in both the milling time and the sintering temperature allowed us to improve the densification and the mechanical properties of the synthesized materials.Aluminosilicato de estroncio, SrAl2Si2O8 (SAS, fue sintetizado por reacción en el estado sólido empleando ceniza volante (CFA como materia prima principal. Una mezcla precursora de SrCO3, CFA y Al2O3 fue activada mecánicamente por tiempos de hasta 12 h en un molino de atrición, y después sinterizada a temperaturas de 900-1300 °C. El empleo de la CFA y la activación mecánica tuvieron el propósito de promover la transformación polimórfica de la fase hexagonal (Hexacelsiana de Sr a la monoclínica (Celsiana de Sr del SAS, ya que esta última se asocia con mejores propiedades físicas y mecánicas pero la primera tiende a aparecer primero. El tamaño promedio de partícula y de cristalita, así como la temperatura al

  2. The experimental modeling of gas percolation mechanisms in a coal-measure tight sandstone reservoir: A case study on the coal-measure tight sandstone gas in the Upper Triassic Xujiahe Formation, Sichuan Basin, China

    Directory of Open Access Journals (Sweden)

    Shizhen Tao

    2016-12-01

    Full Text Available Tight sandstone gas from coal-measure source rock is widespread in China, and it is represented by the Xujiahe Formation of the Sichuan Basin and the Upper Paleozoic of the Ordos Basin. It is affected by planar evaporative hydrocarbon expulsion of coal-measure source rock and the gentle structural background; hydrodynamics and buoyancy play a limited role in the gas migration-accumulation in tight sandstone. Under the conditions of low permeability and speed, non-Darcy flow is quite apparent, it gives rise to gas-water mixed gas zone. In the gas displacing water experiment, the shape of percolation flow curve is mainly influenced by core permeability. The lower the permeability, the higher the starting pressure gradient as well as the more evident the non-Darcy phenomenon will be. In the gas displacing water experiment of tight sandstone, the maximum gas saturation of the core is generally less than 50% (ranging from 30% to 40% and averaging at 38%; it is similar to the actual gas saturation of the gas zone in the subsurface core. The gas saturation and permeability of the core have a logarithm correlation with a correlation coefficient of 0.8915. In the single-phase flow of tight sandstone gas, low-velocity non-Darcy percolation is apparent; the initial flow velocity (Vd exists due to the slippage effect of gas flow. The shape of percolation flow curve of a single-phase gas is primarily controlled by core permeability and confining pressure; the lower the permeability or the higher the confining pressure, the higher the starting pressure (0.02–0.08 MPa/cm, whereas, the higher the quasi-initial flow speed, the longer the nonlinear section and the more obvious the non-Darcy flow will be. The tight sandstone gas seepage mechanism study shows that the lower the reservoir permeability, the higher the starting pressure and the slower the flow velocity will be, this results in the low efficiency of natural gas migration and accumulation as well as

  3. LOW CONCENTRATION MERCURY SORPTION MECHANISMS AND CONTROL BY CALCIUM-BASED SORBENTS; APPLICATION IN COAL-FIRED PROCESSES

    Science.gov (United States)

    The capture of elemental mercury (Hgo) and mercuric chloride (HgCl2) by three types of calcium (Ca)-based sorbents was examined in this bench-scale study under conditions prevalent in coal fired utilities. Ca-based sorbent performances were compared to that of an activated carbon...

  4. Mercury and trace element contents of Donbas coals and associated mine water in the vicinity of Donetsk, Ukraine

    Science.gov (United States)

    Kolker, A.; Panov, B.S.; Panov, Y.B.; Landa, E.R.; Conko, K.M.; Korchemagin, V.A.; Shendrik, T.; McCord, J.D.

    2009-01-01

    Mercury-rich coals in the Donets Basin (Donbas region) of Ukraine were sampled in active underground mines to assess the levels of potentially harmful elements and the potential for dispersion of metals through use of this coal. For 29 samples representing c11 to m3 Carboniferous coals, mercury contents range from 0.02 to 3.5 ppm (whole-coal dry basis). Mercury is well correlated with pyritic sulfur (0.01 to 3.2 wt.%), with an r2 of 0.614 (one outlier excluded). Sulfides in these samples show enrichment of minor constituents in late-stage pyrite formed as a result of interaction of coal with hydrothermal fluids. Mine water sampled at depth and at surface collection points does not show enrichment of trace metals at harmful levels, indicating pyrite stability at subsurface conditions. Four samples of coal exposed in the defunct open-cast Nikitovka mercury mines in Gorlovka have extreme mercury contents of 12.8 to 25.5 ppm. This coal was formerly produced as a byproduct of extracting sandstone-hosted cinnabar ore. Access to these workings is unrestricted and small amounts of extreme mercury-rich coal are collected for domestic use, posing a limited human health hazard. More widespread hazards are posed by the abandoned Nikitovka mercury processing plant, the extensive mercury mine tailings, and mercury enrichment of soils extending into residential areas of Gorlovka.

  5. Study of the pyritized surfaces of the carbon steel components in heavy water production facilities

    International Nuclear Information System (INIS)

    Radulescu, Maria; Parvan, Ioana; Lucan, Dumitra; Fulger, Manuela; Dinu, Alice; Blanatui, A.

    1998-01-01

    The components used in the Girldler Sulfide (GS) process of heavy water production are made of carbon steel covered by iron sulfide layers of different compositions (mackinawite, troilite, pyrrhotite or pyrite) of variable thicknesses. The most protective layers which provide an acceptable corrosion resistance of the subjacent metal are the mixtures of pyrrhotite and pyrite. In the present work, the corrosion resistance of carbon steel samples covered by different types of sulfides was investigated by the following methods: X ray diffraction, metallography and electrochemical methods (potential-dynamical and electrochemical impedance). In order to carry out the electrochemical measurements in the same conditions as those of the operation of carbon steel components in D 2 O production facilities, the experiments were performed with Na 2 S solutions, at pH=4 - 13 and S 2- concentration value between 1 and 1000 mg/l. The dependence of corrosion rate kinetics on pH and S 2- concentration of the testing solution was investigated for sulfide covered samples comparatively with the uncovered ones. Corrosion rates determined gravimetrically were compared with those determined by electrochemical measurements. The uniformity and thickness of the sulfide layers were checked by metallographic methods. The composition of the sulfides formed in various environment conditions was established by X-ray diffraction. Reaction mechanisms specific for sulfide formation environments have been proposed. (authors)

  6. Coal surface control for advanced physical fine coal cleaning technologies. Final report, September 19, 1988--August 31, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Morsi, B.I.; Chiang, S.H.; Sharkey, A.; Blachere, J.; Klinzing, G.; Araujo, G.; Cheng, Y.S.; Gray, R.; Streeter, R.; Bi, H.; Campbell, P.; Chiarlli, P.; Ciocco, M.; Hittle, L.; Kim, S.; Kim, Y.; Perez, L.; Venkatadri, R.

    1992-12-31

    This final report presents the research work carried out on the Coal Surface Control for Advanced Physical Fine Coal Cleaning Technologies project, sponsored by the US Department of Energy, Pittsburgh Energy Technology Center (DOE/PETC). The project was to support the engineering development of the selective agglomeration technology in order to reduce the sulfur content of US coals for controlling SO{sub 2} emissions (i.e., acid rain precursors). The overall effort was a part of the DOE/PETCs Acid Rain Control Initiative (ARCI). The overall objective of the project is to develop techniques for coal surface control prior to the advanced physical fine coal cleaning process of selective agglomeration in order to achieve 85% pyrite sulfur rejection at an energy recovery greater than 85% based on run-of-mine coal. The surface control is meant to encompass surface modification during grinding and laboratory beneficiation testing. The project includes the following tasks: Project planning; methods for analysis of samples; development of standard beneficiation test; grinding studies; modification of particle surface; and exploratory R&D and support. The coal samples used in this project include three base coals, Upper Freeport - Indiana County, PA, Pittsburgh NO. 8 - Belmont County, OH, and Illinois No. 6 - Randolph County, IL, and three additional coals, Upper Freeport - Grant County- WV, Kentucky No. 9 Hopkins County, KY, and Wyodak - Campbell County, WY. A total of 149 drums of coal were received.

  7. Characterization of Coal Porosity for Naturally Tectonically Stressed Coals in Huaibei Coal Field, China

    Science.gov (United States)

    Li, Xiaoshi; Hou, Quanlin; Li, Zhuo; Wei, Mingming

    2014-01-01

    The enrichment of coalbed methane (CBM) and the outburst of gas in a coal mine are closely related to the nanopore structure of coal. The evolutionary characteristics of 12 coal nanopore structures under different natural deformational mechanisms (brittle and ductile deformation) are studied using a scanning electron microscope (SEM) and low-temperature nitrogen adsorption. The results indicate that there are mainly submicropores (2~5 nm) and supermicropores (coal and mesopores (10~100 nm) and micropores (5~10 nm) in brittle deformed coal. The cumulative pore volume (V) and surface area (S) in brittle deformed coal are smaller than those in ductile deformed coal which indicates more adsorption space for gas. The coal with the smaller pores exhibits a large surface area, and coal with the larger pores exhibits a large volume for a given pore volume. We also found that the relationship between S and V turns from a positive correlation to a negative correlation when S > 4 m2/g, with pore sizes coal. The nanopore structure (coal. PMID:25126601

  8. Dressing coals, shales, and the like

    Energy Technology Data Exchange (ETDEWEB)

    Osawa, H

    1938-12-28

    A process for dressing coals, shales, and like carbonaceous substances with the use of floating and sinking phenomena caused by differences in the specific gravities of the substances to be separated in the dressing operation is characterized by the use as the dressing medium of an aqueous suspension of clay and finely ground pyrite or iron ore cinder, or finely ground easily pulverizable iron ore, such as earthy or granular limonite. The aqueous suspension has a low viscosity and a specific gravity between 1.35 and 1.70.

  9. Australian coal

    Energy Technology Data Exchange (ETDEWEB)

    1985-11-01

    Total export shipments of coal in Australia in the year ending June 30 1985 reached a record of 83.8 Mt. The export trade is expected to bring in an income of 4 billion Australian dollars in the current year making coal Australia's biggest revenue-earning export commodity. This article presents a brief overview of the Australian coal industry with production and export statistics and information on major open pit and underground mines.

  10. Study on Gas Field Optimization Distribution with Parameters Adjustment of the Air Duct Outlet for Mechanized Heading Face in Coal Mine

    Science.gov (United States)

    Gong, Xiao-Yan; Zhang, Xin-Yi; Wu, Yue; Xia, Zhi-Xin; Li, Ying

    2017-12-01

    At present, as the increasingly drilling dimensions with cross-section expansion and distance prolong in coal mine, the situation of gas accumulation in mechanized heading face becomes severe. In this paper, optimization research of gas distribution was carried out by adjusting parameters of the air duct outlet, including angle, caliber and the front and rear distance of air duct outlet. Mechanized heading face of Ningtiaota coal mine was taken as the research object, simulated and analyzed the problems of original gas field, the reasonable parameters range of the air duct outlet was determined according to the allowable range of wind speed and the effect of gas dilution, the adjustment range of each parameter of the air duct outlet is preliminarily determined. Base on this, the distribution of gas field under different parameters adjustment of air duct outlet was simulated. The specific parameters under the different distance between the air duct outlet and the mechanized heading face were obtained, and a new method of optimizing the gas distribution by adjusting parameters of the air duct outlet was provided.

  11. Coal - 96

    International Nuclear Information System (INIS)

    Sparre, C.

    1996-09-01

    The report deals mainly with coal consumption, but also gives some information about technology, environmental aspects and markets. Data have been collected by questionnaires or via telephone. The use of steam coal for heating was 0.8 Mtons (down 20% from 1994). Cogeneration plants were the main users. Taxes and environmental reasons cause a reduction of the coal use that will probably continue the next years. Use of steam coal in industry has been constant at a level of 0.7 Mtons. The import of metallurgical coal rests constant at a level of 1.6 Mtons. 1.2 Mtons of coke was produced, and 0.3 Mtons imported. The PFBC-plant at Vaertan, Stockholm used 0.13 Mtons of coal, while some coal fired power plants have been converted to peat and wood fuels. The average price of steam coal imported to Sweden in 1995 was 333 SEK/ton, 6% higher than in 1994. The contract prices for delivery 1996 are about the same as at the end of 1995. All cogeneration plants have some sort of SO 2 removal system, mostly wet-dry. The largest plant, at Vaesteraas, has recently invested in a SCR system for NO x removal. Most other plants are using low NO x burners or SNCR systems, based on ammonia or urea, which reduce the emissions 50 - 70%. Some statistic about the world coal market is also given in the report

  12. Venezuelan coal

    International Nuclear Information System (INIS)

    Vazquez, L.U.

    1991-01-01

    The existence of coal deposits in Venezuela has been known since the early nineteenth century, when the Naricual Mines were discovered in the State of Anzoategui Eastern Venezuela. Through the years the Venezuelan coal business had its ups and downs, but it was not until 1988 that we could properly say that our coal began to play a role in the international market. This paper reports that it is only now, in the nineties, that Venezuelan coal projects have come under a planning, promotional and developmental policy preparing the ground for the great projects Venezuela will have in the not-too-distant future

  13. Quantitative analysis of sulfur forms of coal and the pyrolysis behavior of sulfur compounds; Sekitanchu no io kagobutsu no keitaibetsu gan`yuryo no teiryo to sono netsubunkai kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Mae, K.; Miura, K.; Shimada, M. [Kyoto University, Kyoto (Japan). Faculty of Engineering

    1996-10-28

    As part of the studies on coal utilization basics, considerations were given on quantification of sulfur forms of coal and the pyrolysis behavior of sulfur compounds. With the temperature raising oxidation method, a thermo-balance was connected directly to a mass analyzer, and the coal temperature was raised at a rate of 5{degree}C per minute and gasified. Peak division was performed on SO2 and COS production to derive sulfur forms of coal. Using the slow-speed pyrolysis method, production rates of H2S, COS, SO2 and mercaptans were measured at a temperature raising rate of 20{degree}C per minute. Sulfur content in char was also measured. With the quick pyrolysis method, a Curie point pyrolyzer was connected directly to a gas chromatograph, by which secondary reaction is suppressed, and initial pyrolytic behavior can be tracked. All kinds of coals produce a considerable amount of SO2 in the slow-speed pyrolysis, but very little in the quick pyrolysis. Instead, H2S and mercaptans are produced. Sulfur compound producing mechanisms vary depending on the temperature raising rates. By using a parallel primary reaction model, analysis was made on reactions of H2S production based on different activation energies, such as those generated from pyrite decomposition and organic sulfur decomposition. The analytic result agreed also with that from the temperature raising oxidation method. 4 refs., 6 figs., 1 tab.

  14. Removal of organic and inorganic sulfur from Ohio coal by combined physical and chemical process. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Attia, Y.A.; Zeky, M.El.; Lei, W.W.; Bavarian, F.; Yu, S. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    1989-04-28

    This project consisted of three sections. In the first part, the physical cleaning of Ohio coal by selective flocculation of ultrafine slurry was considered. In the second part, the mild oxidation process for removal of pyritic and organic sulfur.was investigated. Finally, in-the third part, the combined effects of these processes were studied. The physical cleaning and desulfurization of Ohio coal was achieved using selective flocculation of ultrafine coal slurry in conjunction with froth flotation as flocs separation method. The finely disseminated pyrite particles in Ohio coals, in particular Pittsburgh No.8 seam, make it necessary to use ultrafine ({minus}500 mesh) grinding to liberate the pyrite particles. Experiments were performed to identify the ``optimum`` operating conditions for selective flocculation process. The results indicated that the use of a totally hydrophobic flocculant (FR-7A) yielded the lowest levels of mineral matters and total sulfur contents. The use of a selective dispersant (PAAX) increased the rejection of pyritic sulfur further. In addition, different methods of floc separation techniques were tested. It was found that froth flotation system was the most efficient method for separation of small coal flocs.

  15. Iron isotope fractionation during pyrite formation in a sulfidic Precambrian ocean analogue

    Science.gov (United States)

    Rolison, John M.; Stirling, Claudine H.; Middag, Rob; Gault-Ringold, Melanie; George, Ejin; Rijkenberg, Micha J. A.

    2018-04-01

    The chemical response of the Precambrian oceans to rising atmospheric O2 levels remains controversial. The iron isotope signature of sedimentary pyrite is widely used to trace the microbial and redox states of the ocean, yet the iron isotope fractionation accompanying pyrite formation in nature is difficult to constrain due to the complexity of the pyrite formation process, difficulties in translating the iron isotope systematics of experimental studies to natural settings, and insufficient iron isotope datasets for natural euxinic (i.e. anoxic and sulfidic) marine basins where pyrite formation occurs. Herein we demonstrate, that a large, permil-level shift in the isotope composition of dissolved iron occurs in the Black Sea euxinic water column during syngenetic pyrite formation. Specifically, iron removal to syngenetic pyrite gives rise to an iron isotope fractionation factor between Fe(II) and FeS2 of 2.75 permil (‰), the largest yet reported for reactions under natural conditions that do not involve iron redox chemistry. These iron isotope systematics offer the potential to generate permil-level shifts in the sedimentary pyrite iron isotope record due to partial drawdown of the oceanic iron inventory. The implication is that the iron stable isotope signatures of sedimentary pyrites may record fundamental regime shifts between pyrite formation under sulfur-limited conditions and pyrite formation under iron-limited conditions. To this end, the iron isotope signatures of sedimentary pyrite may best represent the extent of euxinia in the past global ocean, rather than its oxygenation state. On this basis, the reinterpreted sedimentary pyrite Fe isotope record suggests a fundamental shift towards more sulfidic oceanic conditions coincident with the 'Great Oxidation Event' around 2.3 billion years ago. Importantly, this does not require the chemical state of the ocean to shift from mainly de-oxygenated to predominantly oxygenated in parallel with the permanent rise

  16. Production of ferric sulphate from pyrite by thiobacillus ferrooxidans. Application to uranium ore leaching

    International Nuclear Information System (INIS)

    Rouas, C.

    1988-12-01

    A process for uranium extraction by oxidizing solutions of ferric sulphate produced by T. ferrooxidans from pyrite is developed. A new counting method specific of T. ferrooxidans is designed. An uranium resistant wild strain, with oxidizing properties as high as the strain ATCC 19859, is isolated. Optimal conditions for ferric sulphate production from pyrite are defined (pH 1.8, density of the medium 1.2%, pyrite granulometry [fr

  17. Non-covalent associative structure of coal

    Energy Technology Data Exchange (ETDEWEB)

    Shui, H. [Anhui University of Technology, Maanshan (China). School of Chemistry and Chemical Engineering

    2004-06-01

    The recent progress of non-covalent associative structure of coal and the mechanisms of the carbon disulphide-N-methyl-2-pyrrolidone (CS{sub 2}/NMP) are mixed solvent and the additive addition enhancing the extraction yield of coals are reviewed, and the aggregation behaviour of coal in solid and solution states are presented, and the aggregation behavior of coal in solid and solution states are introduced in this paper. Coal extraction and swelling in organic solvents at room temperature were the most useful methods to understand the associative structure of coal. CS{sub 2}/NMP is a unique solvent to give high extraction yields for some bituminous coals. Some additives such as tetracyanoethylene (TCNE) can dissociate the stronger interactions among coal molecules and enhance the extraction yields of coal in the mixed solvent. 37 refs., 1 fig.

  18. Mechanical/thermal dehydration - a new process for treatment of peat and coal; Mechanisch/Thermische Entwaesserung - ein neues Verfahren zur Veredelung von Torf und Kohlen

    Energy Technology Data Exchange (ETDEWEB)

    Bergins, C; Berger, S; Strauss, K [Dortmund Univ. (Germany); Elsen, R O [RWE Energie, Essen (Germany); Erken, M [Rheinbraun AG, Koeln (Germany); Bielfeldt, F B [Dieffenbacher, Eppingen (Germany)

    1998-09-01

    In order to keep German brown coal competitive, new technologies for enhanced efficiency of power generation from brown coal were developed in the past few years. At a water content of 50-60 percent by weight, much energy is lost for evaporation. Reduction of the water content will incur a 5 percent effiency enhancement. A new process was developed at Dortmund university, i.e. mechanical/thermal dehydration in which the water contained in brown coal is removed by heat and mechanical pressure. The process is described, and its applicability for other moist fuels, e.g. peat or waste from the paper and wood processing industry ist discussed. (orig./SR) [Deutsch] Damit Braunkohle in Deutschland als heimischer und subventionsfreier Energietraeger diesen Stellenwert behaupten und in Zukunft weiter ausbauen kann, wurde in den letzten Jahren verstaerkt die Entwicklung neuer Technologien zur Effizienzsteigerung der Braunkohleverstromung vorangetrieben. Bei der Verbrennung von Braunkohlen mit Wassergehalten von 50-60 Gew.-% ist in herkoemmlichen Kraftwerken ein erheblicher Teil des Energieinhaltes zur Verdampfung des Wassers mit Hilfe von heissen Rauchgasen in sogenannten Mahltrockungsanlagen erforderlich. Durch eine energetisch guenstige Reduzierung des Wassergehaltes vor der Verbrennung sind hier Wirkungsgradsteigerungen um bis zu 5 Prozentpunkte moeglich. Ein neues, fuer diese Aufgabenstellung einsetzbares Verfahren ist das am Lehrstuhl Energieprozesstechnik und Stroemungsmechanik der Universitaet Dortmund entwickelte Mechanisch/Thermische Entwaesserungsverfahren (MTE-Verfahren). Durch die kombinierte Anwendung von Waerme und mechanischem Druck laesst sich das in der Kohle enthaltene Wasser in fluessiger Form entfernen. Neben der Darstellung des MTE-Verfahrens am Beispiel von Braunkohle soll im folgenden auch auf die Moeglichkeiten der Anwendung des Verfahrens fuer andere feuchte Brennstoffe wie Torf und Abfaelle aus der Papier- und Holzverarbeitung eingegangen werden

  19. Gaseous emissions from coal stockpiles

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-01-15

    Stockpiled coal undergoes atmospheric oxidation and desorption processes during open air storage. These processes release gases to the environment which may effect health and safety by their toxicity and flammability. In extreme cases, this could lead to a fire. This report discusses gaseous emissions from coal stockpiles. It covers gas emission mechanisms, and gas sampling and testing methods, before examining in more detail the principal gases that have been emitted. It concludes that there is limited research in this area and more data are needed to evaluate the risks of gaseous emissions. Some methods used to prevent coal self-heating and spontaneous combustion can be applied to reduce emissions from coal stockpiles.

  20. Cleaning and dewatering fine coal

    Science.gov (United States)

    Yoon, Roe-Hoan; Eraydin, Mert K.; Freeland, Chad

    2017-10-17

    Fine coal is cleaned of its mineral matter impurities and dewatered by mixing the aqueous slurry containing both with a hydrophobic liquid, subjecting the mixture to a phase separation. The resulting hydrophobic liquid phase contains coal particles free of surface moisture and droplets of water stabilized by coal particles, while the aqueous phase contains the mineral matter. By separating the entrained water droplets from the coal particles mechanically, a clean coal product of substantially reduced mineral matter and moisture contents is obtained. The spent hydrophobic liquid is separated from the clean coal product and recycled. The process can also be used to separate one type of hydrophilic particles from another by selectively hydrophobizing one.

  1. Spectroscopic study of cystine adsorption on pyrite surface: From vacuum to solution conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Arenillas, M.; Mateo-Marti, E., E-mail: mateome@cab.inta-csic.es

    2015-09-08

    Highlights: • Successful adsorption of cystine on pyrite surface under several conditions. • Detailed XPS spectroscopic characterization of cystine adsorption on pyrite surface. • Spectroscopy evidence, oxidation and anoxic conditions adjust molecular adsorption. • Molecular chemistry on pyrite is driven depending on the surrounding conditions. • The cystine/pyrite(100) model is in good agreement with Wächtershäuser’s theory. - Abstract: We characterized the adsorption of cystine molecules on pyrite surface via X-ray photoelectron spectroscopy. Anoxic conditions were simulated under ultra-high-vacuum conditions. In contrast, to simulate oxidation conditions, the molecules were adsorbed on pyrite surface from solution. A novel comparative analysis revealed remarkable differences with respect to molecular adsorption and surface chemistry induced by environmental conditions. Molecular adsorption under anoxic conditions was observed to be more favorable, concentrating a large number of molecules on the surface and two different chemical species. In contrast, the presence of oxygen induced an autocatalytic oxidation process on the pyrite surface, which facilitated water binding on pyrite surface and partially blocked molecular adsorption. Pyrite is a highly reactive surface and contains two crucial types of surface functional groups that drive molecular chemistry on the surface depending on the surrounding conditions. Therefore, the system explored in this study holds interesting implications for supporting catalyzed prebiotic chemistry reactions.

  2. Spectroscopic study of cystine adsorption on pyrite surface: From vacuum to solution conditions

    International Nuclear Information System (INIS)

    Sanchez-Arenillas, M.; Mateo-Marti, E.

    2015-01-01

    Highlights: • Successful adsorption of cystine on pyrite surface under several conditions. • Detailed XPS spectroscopic characterization of cystine adsorption on pyrite surface. • Spectroscopy evidence, oxidation and anoxic conditions adjust molecular adsorption. • Molecular chemistry on pyrite is driven depending on the surrounding conditions. • The cystine/pyrite(100) model is in good agreement with Wächtershäuser’s theory. - Abstract: We characterized the adsorption of cystine molecules on pyrite surface via X-ray photoelectron spectroscopy. Anoxic conditions were simulated under ultra-high-vacuum conditions. In contrast, to simulate oxidation conditions, the molecules were adsorbed on pyrite surface from solution. A novel comparative analysis revealed remarkable differences with respect to molecular adsorption and surface chemistry induced by environmental conditions. Molecular adsorption under anoxic conditions was observed to be more favorable, concentrating a large number of molecules on the surface and two different chemical species. In contrast, the presence of oxygen induced an autocatalytic oxidation process on the pyrite surface, which facilitated water binding on pyrite surface and partially blocked molecular adsorption. Pyrite is a highly reactive surface and contains two crucial types of surface functional groups that drive molecular chemistry on the surface depending on the surrounding conditions. Therefore, the system explored in this study holds interesting implications for supporting catalyzed prebiotic chemistry reactions

  3. Silane-based coatings on the pyrite for remediation of acid mine drainage.

    Science.gov (United States)

    Diao, Zenghui; Shi, Taihong; Wang, Shizhong; Huang, Xiongfei; Zhang, Tao; Tang, Yetao; Zhang, Xiaying; Qiu, Rongliang

    2013-09-01

    Acid mine drainage (AMD) resulting from the oxidation of pyrite and other metal sulfides has caused significant environmental problems, including acidification of rivers and streams as well as leaching of toxic metals. With the goal of controlling AMD at the source, we evaluated the potential of tetraethylorthosilicate (TEOS) and n-propyltrimethoxysilane (NPS) coatings to suppress pyrite oxidation. The release of total Fe and SO4(-2) from uncoated and coated pyrite in the presence of a chemical oxidizing agent (H2O2) or iron-oxidizing bacteria (Acidithiobacillus ferrooxidans) was measured. Results showed that TEOS- and NPS-based coatings reduced chemical oxidation of pyrite by as much as 59 and 96% (based on Fe release), respectively, while biological oxidation of pyrite was reduced by 69 and 95%, respectively. These results were attributed to the formation of a dense network of Fe-O-Si and Si-O-Si bonds on the pyrite surface that limited permeation of oxygen, water, and bacteria. Compared with results for TEOS-coated pyrite, higher pH and lower concentrations of total Fe and SO4(-2) were observed for oxidation of NPS-coated pyrite, which was attributed to its crack-free morphology and the presence of hydrophobic groups on the NPS-based coating surface. The silane-based NPS coating was shown to be highly effective in suppressing pyrite oxidation, making it a promising alternative for remediation of AMD at its source. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Coal summit II

    Energy Technology Data Exchange (ETDEWEB)

    1983-01-01

    Various papers were presented on world coal trade. Papers include: Poland as a producer and exporter of coal; the dynamics of world coal trade; Cerrejon coal production perspectives; present state of the Australian coal industry; present state of the EC coal market and future prospects; prospects of US coal exports to Europe; forecast of Italian coal supply and demand through 1990; statistics from coal transportation outlook; status of world coal ports.

  5. Investigation into Mechanism of Floor Dynamic Rupture by Evolution Characteristics of Stress and Mine Tremors: A Case Study in Guojiahe Coal Mine, China

    Directory of Open Access Journals (Sweden)

    Guangjian Liu

    2018-01-01

    Full Text Available In order to explore the mechanism of floor dynamic rupture, the current study adopts a thin plate model to further investigate the condition of floor failure. One of the possible explanations could be floor buckling due to high horizontal stress and dynamic disturbance ultimately leading to rapid and massive release of elastic energy thus inducing dynamic rupture. Seismic computed tomography and 3D location were employed to explore the evolution characteristics of floor stress distribution and positions of mine tremors. In the regions of floor dynamic rupture, higher P-wave velocity was recorded prior to the dynamic rupture. On the contrary, relatively lower reading was observed after the dynamic rupture thus depicting a high stress concentration condition. Meanwhile, evolution of mine tremors revealed the accumulation and subsequent release of energy during the dynamic rupture process. It was further revealed that dynamic rupture was induced due to the superposition of static and dynamic stresses: (i the high static stress concentration due to frontal and lateral abutment stress from coal pillar and (ii dynamic stress from the fracture and caving of coal pillar, hard roof, and key stratum. In the later part of this study, the floor dynamic rupture occurrence process would be reproduced through numerical simulations within a 0.6 sec time frame. The above-mentioned findings would be used to propose a feasible mechanism for prewarning and prevention of floor dynamic rupture using seismic computed tomography and mine tremors 3D location.

  6. Variation in mineral composition of coal during enrichment and coking

    Energy Technology Data Exchange (ETDEWEB)

    M.L. Ulanovskii; A.N. Likhenko [Ukrkoks Coke Producers' Association, Dnepropetrovsk (Ukraine)

    2009-06-15

    The parameters I{sub b} and B{sub b} used in developing an optimal coking-batch composition are determined from data on the chemical composition of the ash in Donetsk Basin and other coal. It is found that, when the ash content is reduced in deeper enrichment of coal with an increased content of fine pyrite, there will be accompanying increase in the Fe{sub 2}O{sub 3} content and decrease in the SiO{sub 2} content of the ash in lighter fractions. This increases I{sub b}. In other words, reducing the ash content of the coal is an unpromising means of increasing CRI and CSR of the coke produced. Three ash-containing elements (silicon, aluminum, and iron) are experimentally proven to transfer from coal to coke. Specific behavior of calcium, magnesium, alkali metals, and sulfur during coking.

  7. Risk Analysis and Prediction of Floor Failure Mechanisms at Longwall Face in Parvadeh-I Coal Mine using Rock Engineering System (RES)

    Science.gov (United States)

    Aghababaei, Sajjad; Saeedi, Gholamreza; Jalalifar, Hossein

    2016-05-01

    The floor failure at longwall face decreases productivity and safety, increases operation costs, and causes other serious problems. In Parvadeh-I coal mine, the timber is used to prevent the puncture of powered support base into the floor. In this paper, a rock engineering system (RES)-based model is presented to evaluate the risk of floor failure mechanisms at the longwall face of E 2 and W 1 panels. The presented model is used to determine the most probable floor failure mechanism, effective factors, damaged regions and remedial actions. From the analyzed results, it is found that soft floor failure is dominant in the floor failure mechanism at Parvadeh-I coal mine. The average of vulnerability index (VI) for soft, buckling and compressive floor failure mechanisms was estimated equal to 52, 43 and 30 for both panels, respectively. By determining the critical VI for soft floor failure mechanism equal to 54, the percentage of regions with VIs beyond the critical VI in E 2 and W 1 panels is equal to 65.5 and 30, respectively. The percentage of damaged regions showed that the excess amount of used timber to prevent the puncture of weak floor below the powered support base is equal to 4,180,739 kg. RES outputs and analyzed results showed that setting and yielding load of powered supports, length of face, existent water at face, geometry of powered supports, changing the cutting pattern at longwall face and limiting the panels to damaged regions with supercritical VIs could be considered to control the soft floor failure in this mine. The results of this research could be used as a useful tool to identify the damaged regions prior to mining operation at longwall panel for the same conditions.

  8. Electrochemical Properties for Co-Doped Pyrite with High Conductivity

    Directory of Open Access Journals (Sweden)

    Yongchao Liu

    2015-09-01

    Full Text Available In this paper, the hydrothermal method was adopted to synthesize nanostructure Co-doped pyrite (FeS2. The structural properties and morphology of the synthesized materials were characterized using X-ray diffraction (XRD and scanning electron microscopy (SEM, respectively. Co in the crystal lattice of FeS2 could change the growth rate of different crystal planes of the crystal particles, which resulted in various polyhedrons with clear faces and sharp outlines. In addition, the electrochemical performance of the doping pyrite in Li/FeS2 batteries was evaluated using the galvanostatic discharge test, cyclic voltammetry and electrochemical impedance spectroscopy. The results showed that the discharge capacity of the doped material (801.8 mAh·g−1 with a doping ratio of 7% was significantly higher than that of the original FeS2 (574.6 mAh·g−1 because of the enhanced conductivity. Therefore, the doping method is potentially effective for improving the electrochemical performance of FeS2.

  9. International Coal Report's coal year 1991

    Energy Technology Data Exchange (ETDEWEB)

    McCloskey, G [ed.

    1991-05-31

    Following introductory articles on factors affecting trade in coal and developments in the freight market, tables are given for coal exports and coal imports for major countries worldwide for 1989 and 1990. Figures are also included for coal consumption in Canada and the Eastern bloc,, power station consumption in Japan, coal supply and demand in the UK, electric utility coal consumption and stocks in the USA, coal production in Australia, Canada and USA by state, and world hard coal production. A final section gives electricity production and hard coal deliveries in the EEC, sales of imported and local coal and world production of pig iron and steel.

  10. Elucidating the mechanism of Cr(VI) formation upon the interaction with metal oxides during coal oxy-fuel combustion.

    Science.gov (United States)

    Chen, Juan; Jiao, Facun; Zhang, Lian; Yao, Hong; Ninomiya, Yoshihiko

    2013-10-15

    The thermodynamics underpinning the interaction of Cr-bearing species with basic metal oxides, i.e. K2O, Fe2O3, MgO and CaO, during the air and oxy-fuel combustion of coal have been examined. The synchrotron-based X-ray adsorption near-edge spectroscopy (XANES) was used for Cr speciation. For the oxides tested, Cr(VI) formation is dominated by the reduction potential of the metals. The oxides of Ca(2+) with high reduction potential favored the oxidation of Cr(III), same for K(+). The other two basic metals, Fe2O3 and MgO with lower reduction potentials reacted with Cr(III) to form the corresponding chromites at the temperatures above 600°C. Coal combustion experiments in drop-tube furnace have confirmed the rapid capture of Cr vapors, either trivalent or hexavalent, by CaO into solid ash. The existence of HCl in flue gas favored the vaporization of Cr as CrO2Cl2, which was in turn captured by CaO into chromate. Both Fe2O3 and MgO exhibited less capability on scavenging the Cr(VI) vapor. Particularly, MgO alone exhibited a low capability for capturing the vaporized Cr(III) vapors. However, its co-existence with CaO in the furnace inhibited the Cr(VI) formation. This is beneficial for minimizing the toxicity of Cr in the coal combustion-derived fly ash. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Research of Dust Field Optimization Distribution Based on Parameters Change of Air Duct Outlet in Fully Mechanized Excavation Face of Coal Mine

    Science.gov (United States)

    Gong, Xiao-Yan; Xia, Zhi-Xin; Wu, Yue; Mo, Jin-Ming; Zhang, Xin-Yi

    2017-12-01

    Aiming at the problem of dust accumulation and pollution risk rising sharply in fully mechanized excavation face, which caused by the unreasonable air duct outlet airflow under the long distance driving, this paper proposes a new idea to optimize the distribution of dust by changing the angle, caliber and the front and rear distance of air duct outlet. Taking the fully mechanized excavation face of Ningtiaota coal mine which located in Shaanxi province as the research object, the numerical simulation scheme of dust field was established, the safety hazard of the distribution of original dust field was simulated and analyzed, the numerical simulation and optimization analysis of the dust distribution by changing the angle, caliber and the front and rear distance of air duct outlet was carried out, and the adjustment scheme of the optimized dust distribution was obtained, which provides a theoretical basis for reducing the probability of dust explosion and the degree of pollution.

  12. POC-SCALE TESTING OF A DRY TRIBOELECTROSTATIC SEPARATOR FOR FINE COAL CLEANING

    Energy Technology Data Exchange (ETDEWEB)

    R.H. Yoon; G.H. Luttrell; E.S. Yan; A.D. Walters

    2001-04-30

    Numerous advanced coal cleaning processes have been developed in recent years that are capable of substantially reducing both ash- and sulfur-forming minerals from coal. However, most of the processes involve fine grinding and use water as the cleaning medium; therefore, the clean coal products must be dewatered before they can be transported and burned. Unfortunately, dewatering fine coal is costly, which makes it difficult to deploy advanced coal cleaning processes for commercial applications. As a means of avoiding problems associated with the fine coal dewatering, the National Energy Technology Laboratory (NETL) developed a dry coal cleaning process in which mineral matter is separated from coal without using water. In this process, pulverized coal is subjected to triboelectrification before being placed in an electric field for electrostatic separation. The triboelectrification is accomplished by passing a pulverized coal through an in-line mixer made of copper. Copper has a work function that lies between that of carbonaceous material (coal) and mineral matter. Thus, coal particles impinging on the copper wall lose electrons to the metal thereby acquiring positive charges, while mineral matter impinging on the wall gain electrons to acquire negative charges. The charged particles then pass through an electric field where they are separated according to their charges into two or more products depending on the configuration of the separator. The results obtained at NETL showed that it is capable of removing more than 90% of the pyritic sulfur and 70% of the ash-forming minerals from a number of eastern U.S. coals. However, the BTU recoveries were less than desirable. The laboratory-scale batch triboelectrostatic separator (TES) used by NETL relied on adhering charged particles on parallel electrode surfaces and scraping them off. Therefore, its throughput will be proportional to the electrode surface area. If this laboratory device is scaled-up as is, it would

  13. Behavior of catalyst and mineral matter in coal liquefaction; Sekitan ekika hannochu no kobusshitsu to shokubai no kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Iwasaki, K.; Wang, J.; Tomita, A. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

    1996-10-28

    Mineral matter in coals is important in various senses for coal liquefaction. It is possible that the catalytic activity is affected by the interaction between catalyst and mineral matter. Iron-based catalyst forms pyrrhotite in the process of liquefaction, but the interaction between it and mineral matter is not known in detail. In this study, the interaction between mineral matter and catalyst and the selective reaction between them were investigated. Tanito Harum coal was used for this study. This coal contains a slight amount of siderite and jarosite besides pyrite as iron compounds. Liquefaction samples were obtained from the 1 t/d NEDOL process PSU. The solid deposits in the reactor mainly contained pyrrhotite and quartz. A slight amount of kaolinite was observed, and pyrite was little remained. It was found that the catalyst (pyrrhotite) often coexisted with quartz, clay and calcite. 8 figs., 2 tabs.

  14. Emission allowance trading under the Clean Air Act Amendments: An incentive mechanism for the adoption of Clean Coal Technologies

    International Nuclear Information System (INIS)

    South, D.W.; McDermott, K.A.

    1993-01-01

    Title IV of the Clean Air Act Amendments of 1990 (P.L. 101-549) uses tradeable SO 2 allowances as a means of reducing acidic emissions from the electricity generating industry. The use of emission allowances generates two important results; first, utilities are given the flexibility to choose their optimal (least cost) compliance strategies and second, the use of emission allowances creates greater incentives for the development and commercialization of innovative emissions control technology. Clean Coal Technologies (CCTs) are able to generate electricity more efficiently, use a wide variety of coal grades and types, and dramatically reduce emissions of SO 2 , NO x , CO 2 , and PM per kWh. However, development and adoption of the technology is limited by a variety of regulatory and technological risks. The use of SO 2 emission allowances may be able to provide incentives for utility (and nonutility) adoption of this innovative technology. Emission allowances permit the utility to minimize costs on a systemwide basis and provides rewards for addition emission reductions. As CCTs are a more efficient and low emitting source of electricity, the development and implementation of this technology is desirable. This paper will explore the relationship between the incentives created by the SO 2 allowance market and CCT development. Regulatory hindrances and boons for the allowance market shall also be identified to analyze how market development, state mandates, and incentive regulation will effect the ability of allowances to prompt CCT adoption

  15. Engineering development of advanced physical fine coal cleaning technologies - froth flotation

    Energy Technology Data Exchange (ETDEWEB)

    Ferris, D.D.; Bencho, J.R. [ICF Kaiser Engineers, Inc., Pittsburgh, PA (United States)

    1995-11-01

    In 1988, ICF Kaiser Engineers was awarded DOE Contract No. DE-AC22-88PC88881 to research, develop, engineer and design a commercially acceptable advanced froth flotation coal cleaning technology. The DOE initiative is in support of the continued utilization of our most abundant energy resource. Besides the goal of commercialability, coal cleaning performance and product quality goals were established by the DOE for this and similar projects. primary among these were the goals of 85 percent energy recovery and 85 percent pyrite rejection. Three nationally important coal resources were used for this project: the Pittsburgh No. 8 coal, the Upper Freeport coal, and the Illinois No. 6 coal. Following is a summary of the key findings of this project.

  16. Paleoredoc and pyritization of soft-bodied fossils in the Ordovician Frankfort Shale of New York

    DEFF Research Database (Denmark)

    Farrell, Una C.; Briggs, Derek E. G.; Hammarlund, Emma U.

    2013-01-01

    Multiple beds in the Frankfort Shale (Upper Ordovician, New York State), including the original "Beecher's Trilobite Bed," yield fossils with pyritized soft-tissues. A bed-by-bed geochemical and sedimentological analysis was carried out to test previous models of soft-tissue pyritization...

  17. Relationship between pyrite Stability and arsenic mobility during aquifer storage and recovery in southwest central Florida.

    Science.gov (United States)

    Jones, Gregg W; Pichler, Thomas

    2007-02-01

    Elevated arsenic concentrations are common in water recovered from aquifer storage and recovery (ASR) systems in west-central Florida that store surface water. Investigations of the Suwannee Limestone of the Upper Floridan aquifer, the storage zone for ASR systems, have shown that arsenic is highest in pyrite in zones of high moldic porosity. Geochemical modeling was employed to examine pyrite stability in limestone during simulated injections of surface water into wells open only to the Suwannee Limestone with known mineralogy and water chemistry. The goal was to determine if aquifer redox conditions could be altered to the degree of pyrite instability. Increasing amounts of injection water were added to native storage-zone water, and resulting reaction paths were plotted on pyrite stability diagrams. Native storage-zone water plotted within the pyrite stability field, indicating that conditions were sufficiently reducing to allow for pyrite stability. Thus, arsenic is immobilized in pyrite, and its groundwater concentration should be low. This was corroborated by analysis of water samples, none of which had arsenic concentrations above 0.036 microg/L. During simulation, however, as injection/native storage-zone water ratios increased, conditions became less reducing and pyrite became unstable. The result would be release of arsenic from limestone into storage-zone water.

  18. Isotopic and microbiological signatures of pyrite-driven denitrification in a sandy aquifer

    NARCIS (Netherlands)

    Zhang, Y.-C.; Slomp, C.P.; Broers, H.P.; Bostick, B.; Passier, H.F.; Böttcher, M.E.; Omoregie, E.O.; Lloyd, J.R.; Polya, D.A.; Van Cappellen, P.

    2012-01-01

    Denitrificationdriven by pyrite oxidation can play a major role in the removal of nitrate from groundwater systems. As yet, limited information is available on the interactions between the micro-organisms and aqueous and mineral phases in aquifers where pyrite oxidation is occurring. In this study,

  19. Isotopic and microbiological signatures of pyrite-driven denitrification in a sandy aquifer

    NARCIS (Netherlands)

    Zhang, Y.C.; Slomp, C.P.; Broers, H.P.; Bostick, B.; Passier, H.F.; Böttcher, M.E.; Omoregie, E.O.; Lloyd, J.R.; Polya, D.A.; Cappellen, P. van

    2012-01-01

    Denitrification driven by pyrite oxidation can play a major role in the removal of nitrate from groundwater systems. As yet, limited information is available on the interactions between the micro-organisms and aqueous and mineral phases in aquifers where pyrite oxidation is occurring. In this study,

  20. Gasifier feed: Tailor-made from Illinois coals. Technical report, September 1, 1991--November 30, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Ehrlinger, H.P. III

    1991-12-31

    The purpose of this research is to develop a coal slurry from waste streams using Illinois coal that is ideally suited for a gasification feed. The principle items to be studied are (1) methods of concentrating pyrite and decreasing other ash forming minerals into a high grade gasification feed using froth flotation and gravity separation techniques; (2) chemical and particle size analyses of coal slurries; (3) determination of how that slurry can be densified and to what degree of densification is optimum from the pumpability and combustibility analyses; and (4) reactivity studies.

  1. Mechanisms of Vanadium Recovery from Stone Coal by Novel BaCO3/CaO Composite Additive Roasting and Acid Leaching Technology

    Directory of Open Access Journals (Sweden)

    Zhenlei Cai

    2016-03-01

    Full Text Available In this report, the vanadium recovery mechanisms by novel BaCO3/CaO composite additive roasting and acid leaching technology, including the phase transformations and the vanadium leaching kinetics, were studied. The purpose of this manuscript is to realize and improve the vanadium recovery from stone coal using BaCO3/CaO as the composite additive. The results indicated that during the composite additive BaCO3/CaO roasting process, the monoclinic crystalline structure of muscovite (K(Al,V2[Si3AlO10](OH2 was converted into the hexagonal crystalline structure of BaSi4O9 and the tetragonal crystalline structure of Gehlenite (Ca2Al2SiO7, which could, therefore, facilitate the release and extraction of vanadium. Vanadium in leaching residue was probably in the form of vanadate or pyrovanadate of barium and calcium, which were hardly extracted during the sulfuric acid leaching process. The vanadium leaching kinetic analysis indicated that the leaching process was controlled by the diffusion through a product layer. The apparent activation energy could be achieved as 46.51 kJ/mol. The reaction order with respect to the sulfuric acid concentration was 1.1059. The kinetic model of vanadium recovery from stone coal using novel composite additive BaCO3/CaO could be finally established.

  2. Development of a phenomenological model for coal slurry atomization

    Energy Technology Data Exchange (ETDEWEB)

    Dooher, J.P. [Adelphi Univ., Garden City, NY (United States)

    1995-11-01

    Highly concentrated suspensions of coal particles in water or alternate fluids appear to have a wide range of applications for energy production. For enhanced implementation of coal slurry fuel technology, an understanding of coal slurry atomization as a function coal and slurry properties for specific mechanical configurations of nozzle atomizers should be developed.

  3. Environmental impact of differently remediated hard coal overburden and tailings dumps a few decades after remediation

    International Nuclear Information System (INIS)

    Willscher, S.; Felix, M.; Sohr, A.

    2010-01-01

    Coal mining in the Saxony region of Germany has caused heavy metal and arsenic pollution in adjacent groundwater and surface waters. Coal waste dumping sites are leaching heavy metals and metalloids in the form of fine precipitates into local rivers. This paper studied the different remediation strategies used at 3 different dump sites in the area. The aim of the study was to determine the environmental impact of the dumps and evaluate the long-term effects of remediation measures. The dumps consisted of coarse to fine-grained materials from former processing activities, and contained pyrite in varying concentrations. Samples from different depth as well as groundwater samples were taken from the sites and investigated for their mechanical, geological, geochemical, biogeochemical, and physico-chemical characteristics. Seepage formation rates and contaminant loads at the dump sites were compared. The study showed that the revegetation of dump surfaces can help to prevent against erosion, but cannot prevent acid mine drainage (AMD) generation. The additional seals and covers placed at 2 of the dumps resulted in a high reduction of seepage waters, and almost no acidification of dump materials. 5 refs., 1 fig.

  4. Coal competitiveness?

    International Nuclear Information System (INIS)

    Rogeaux, B.

    2006-01-01

    Will coal electrical plants be more competitive in the coming years? Answering this one cannot be limited to merely comparing estimates based on reference electricity production costs. The competitiveness of coal will indeed depend on the final product marketed, as the MWhs are not equal: is the purpose to produce base, half-base MWh? Does the electrical equipment structure require flexible MWh (for instance in the event of significant intermittent renewable energy amounts), and therefore plants able to adjust their power rapidly? But the competitiveness of coal will also depend on many factors that will correct reference cost estimates: uncertainties, risks, externalities. These factors will need to be appreciated on a case by case basis. We introduce some of the reasoning used to better appreciate the future competitiveness of coal, and the main factors conditioning it in three contrasting regions of the world: Europe, USA, china. (author)

  5. Production method test for the mechanizing exploitation of coal subvertical layer; Ensayo en produccion de un metodo para la explotacion altamente mecanizada de capas subverticales de carbon de mediana potencia (2-3 m)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    In the carboniferous locations and more concretely in those in that the disposition of the strata, is subvertical, a great problem is believed for its exploitation by interior mining. We remember that a very important part of the reservation of coal in the different Asturian basins has a disposition of this type. With the step of the time, what constituted 100% of conventional outburst in a principle, that is to say by means of hammer picador (system of headwall), they left mechanizing the different exploitations. A very important and decisive factor, besides other, was the power of the layer of coal to choose a mechanization system. We have this way that, for the layers of inferior powers (0,70 to 2,00 m) they can be mecanizables by means of coal cutter and pole or by means equipment of machine coal-mining (for example Asturfalia RST3). For those layers with superior powers to the 4 m, the most widespread method and that is supposes a high mechanization range, it is the horizontal and soutiraje of the key of coal for shot with explosive of security or compressed air to very high pressure. It exists a very important lagoon then as for their mechanization she refers, for those powers of the layers of coal of between 2 and 3. With this Project and thanks to the financing of OCICARBON, he seeks to start a denominated system of exploitation soutiraje of narrow layer, to attack the mechanization of the layers with powers from 2 to 3 m, what would close the mechanization of the whole fan of powers of the present layers of coal in our locations with the mentioned disposition. With this Project an increase is also sought as for the yields he refers, as well as a humanization of the works in mine interior, starting a miner of court strait for the advance of the subnivles, different pole types, as well as the application of several shot systems to the key of local. Everything should lead it to an optimization of the mechanization of layers subvertical of coal with powers of

  6. Coal - 97

    International Nuclear Information System (INIS)

    Sparre, C.

    1997-01-01

    The report deals with the use of coal and coke during 1996. Some information about techniques, environmental questions and markets are also given. Data have been collected by questionnaires to major users and by telephone to minor users. Preliminary statistical data from SCB have also been used. The use of steam coal for heating purposes during 1996 was 1,2 mill tons and 50% higher than in 1995. The increase is probably temporary and due to high prices of electricity because of lack of water power. The co-generation plants were the main users of coal. The minor plants have increased their use of forest fuels. Probably the use of steam coal will go down in the immediate years both in the heat generating and the co-generation plants. During the top year 1987 coal was used in 18 hotwater plants and 11 co-generation plants. 1996 these figures are 3 and 12. Taxes and environmental reasons explain this trend. The use of steam coal in the industry has been constant at the level 700 000 tons. This level is supposed to be constant or to vary with business cycles. The import of metallurgical coal in 1996 was 1,6 mill tons like the year before. 1,2 mill tons coke were produced. The coke consumption in the industry was 1,5 mill tons. 0,3 mill tons of coke were imported. The average price of steam coal imported in Sweden in 1996 was 340 SEK/ton or 2% higher than in 1995. For the world, the average import price was 51,5 USD/ton, nearly the same as the year before. The contract prices for delivery during 1997 are about equal as the end of 1996. All Swedish plants meet their emission limits of dust, SO 2 and NO x given by county administrations or concession boards

  7. Field tracer test for denitrification in a pyrite-bearing schist aquifer

    International Nuclear Information System (INIS)

    Pauwels, H.; Kloppmann, W.; Foucher, J.-C.; Martelat, A.; Fritsche, V.

    1998-01-01

    A small-scale artificial tracer test performed on a schist aquifer in Brittany has helped clarify mechanisms and kinetics of in situ autotrophic denitrification. NO 3 was injected as a pulse simultaneously with a conservative tracer - Br - . During the test, which lasted 210 h, 73% of the injected Br - was recovered, as against only 47% of the NO 3 . The 26% difference in the recovery of the two injected species is interpreted as being the result of denitrification, in part due to the direct oxidation of pyrite present in the solid aquifer according to the reaction: 5FeS 2 +14NO 3 - +4H + approaches7N 2 +10SO 4 2- +5Fe 2+ +2H 2 O, and in part due to subsequent iron oxidation according to the reaction: NO 3 - +5Fe 2+ +6H + approaches1/2N 2 +5Fe 3+ +3H 2 O. Despite the potential increase in SO 4 and Fe resulting from denitrification through pyrite oxidation, the concentrations of these elements in the groundwater remain moderate due to the precipitation of minerals such as jarosite and/or natroalunite. Tracer transfer takes place in a heterogeneous medium which, according to the breakthrough curves, can be simplified to a dual-porosity aquifer comprising a high-permeability (fractures or large fissures) medium of low porosity from which only minor denitrification of circulating NO 3 -bearing water was observed and a low-permeability (small fissures) medium of high porosity which induces a higher denitrification rate in the circulating NO 3 -bearing water. The kinetics of the denitrification reaction are high compared with results obtained for other environments and can be described by a first-order model with a half life of 7.9 days for the low-porosity medium and only 2.1 days for the high-porosity medium. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  8. Conditioning in the flotation of gold, uranium oxide, and pyrite

    International Nuclear Information System (INIS)

    Stassen, F.J.N.

    1991-01-01

    The effect of conditioning energy on the flotation of gold, U 3 O 8 , and pyrite was investigated in the range 0,1 to 100 kWh per tonne of dry ore for various combinations of conditioning time and impeller speed in a cylindrical conditioning tank. It was found that, when the conditioning energy was increased to between 5 and 10 kWh per tonne of dry ore, the total recovery and flotation rate of the valuable minerals (expressed as Klimpel parameters) increased substantially. The Klimpel parameters are dependent on conditioning energy, but are independent of conditioning time or impeller speed (at constant conditioning energy). The Klimpel parameters of the gangue are independent of conditioning energy. 23 refs., 7 tabs., 2 figs

  9. Coal -98

    International Nuclear Information System (INIS)

    Sparre, C.

    1998-01-01

    The following report deals with the use of coal and coke during 1997. Some information about technic, environmental questions and markets are also given. Data have been collected by questionnaires to major users and by telephone to minor users. Preliminary statistical data from SCB have also been used. The use of steam coal for heating purposes during 1997 was 730 000 tons and about 500 000 tons lower than in 1996. The extremely high figures of 1996 were due to twice the production of electricity because of lack of hydro power. The co-generation plants were the main users of coal. The minor plants have increased their use of forest fuels. Probably the use of steam coal will go down in the immediate years both in the heat generating and the co-generating plants. Some foreign analysts, however, estimate a doubled use of coal for energy use after 2020 because of the plans to phase out the nuclear power. During the top year 1987 coal was used in 18 hot water plants and 11 co-generation plants. 1997 these figures are 2 and 8. Taxes and environmental reasons explain this trend. The use of steam coal in the industry has been constant at the level 700 000 tons. This level is supposed to be constant or to vary with business cycles. The import of metallurgical coal in 1997 was 1.6 mill tons like the year before. 1.2 mill tons coke were produced. The coke consumption in the industry was 1.5 Mill tons. 0.3 mill tons of coke were imported. Several other plants have plans to replace the coal with forest fuels, waste fuels and NG. Even the biggest plant, Vaesteraas, has plans to build a block for bio fuels. Helsingborg has started to use wood pellets. The pellets replace most of the coal for the heat production in the co-generation plant. Norrkoeping Kraft AB has taken a fluid bed boiler for different fuels in operation, leading to more than half the coal consumption compared with previous years. They have also rebuilt one of their travelling grates for bio fuels. Stockholm

  10. The volcanic-sedimentary sequence of the Lousal deposit, Iberian Pyrite Belt (Portugal)

    Science.gov (United States)

    Rosa, Carlos; Rosa, Diogo; Matos, Joao; Relvas, Jorge

    2010-05-01

    dominant fragmentation mechanism. Unlike many locations of the IPB, fiamme-rich pyroclastic units were not identified at Lousal. The ore deposits occur in close proximity with this volcanic centre that may have driven hydrothermal circulation that led to ore formation. The volcanic rocks show intense chloritic alteration, indicating that the mineralizing event occurred after most of the rhyolitic units have emplaced. The massive sulfides show abundant sedimentary structures which is not typical in the massive sulfide deposits of the IPB. The Lousal 50 Mt massive sulfide deposit consists of at least 11 ore bodies and was exploited until 1988 mainly for pyrite. The ores mined averaged 0.7% Cu, 0.8%Pb e 1.4%Zn (Strauss, 1971). These relatively low base metal grades led to an evaluation of the contents and distribution of high-tech element in the ore bodies, which would improve the economic viability of mining the deposit. This evaluation is currently focusing on the distribution and mineralogy of selenium, as ores mined in the past were known to be rich in this element. This work benefits from research projects INCA (PTDC/CTE-GIN/67027/2006; Characterization of crucial mineral resources for the development of renewable energy technologies: The Iberian Pyrite Belt ores as a source of indium and other high-technology elements) and project ARCHYMEDES II (POCTI/CTA/45873/2002), both funded by the Fundação para a Ciência e Tecnologia. REFERENCES Strauss, G.K., 1970. Sobre la geologia de la provincia piritifera del Suroeste de la Peninsula Iberica y sus yacimientos, en especial sobre la mina de pirita de Lousal (Portugal): Memoria del IGME 77, 1-266. Tornos, F., 2006. Environment of formation and styles of volcanogenic massive sulfides: The Iberian Pyrite Belt. Ore Geology Reviews 28, 259-307.

  11. Modes of occurrence of potentially hazardous elements in coal: levels of confidence

    Science.gov (United States)

    Finkelman, R.B.

    1994-01-01

    The modes of occurrence of the potentially hazardous elements in coal will be of significance in any attempt to reduce their mobilization due to coal combustion. Antimony and selenium may be present in solid solution in pyrite, as minute accessory sulfides dispersed throughout the organic matrix, or in organic association. Because of these modes of occurrence it is anticipated that less than 50% of these elements will be routinely removed by conventional coal cleaning procedures. Arsenic and mercury occur primarily in late-stage coarse-grained pyrite therefore physical coal cleaning procedures should be successful in removing substantial proportions of these elements. Cadmium occurs in sphalerite and lead in galena. Both of these minerals exhibit a wide range of particle sizes and textural relations. Depending on the particle size and textural relations, physical coal cleaning may remove as little as 25% of these elements or as much as 75%. Manganese in bituminous coal occurs in carbonates, especially siderite. Physical coal cleaning should remove a substantial proportion of this element. More information is needed to elucidate the modes of occurrence of beryllium, chromium, cobalt, and nickel. ?? 1994.

  12. Potential use of pyrite cinders as raw material in cement production: results of industrial scale trial operations.

    Science.gov (United States)

    Alp, I; Deveci, H; Yazici, E Y; Türk, T; Süngün, Y H

    2009-07-15

    Pyrite cinders, which are the waste products of sulphuric acid manufacturing plants, contain hazardous heavy metals with potential environmental risks for disposal. In this study, the potential use of pyrite cinders (PyCs) as iron source in the production of Portland cement clinker was demonstrated at the industrial scale. The chemical and mineralogical analyses of the PyC sample used in this study have revealed that it is essentially a suitable raw material for use as iron source since it contains >87% Fe(2)O(3) mainly in the form of hematite (Fe(2)O(3)) and magnetite (Fe(3)O(4)). The samples of the clinkers produced from PyC in the industrial scale trial operation of 6 months were tested for the conformity of their chemical composition and the physico-mechanical performance of the resultant cement products. The data were compared with the clinker products of the iron ore, which is used as the raw material for the production Portland cement clinker in the plant. The chemical compositions of all the clinker products of PyC appeared to conform to those of the iron ore clinker, and hence, a Portland cement clinker. The mechanical performance of the mortars prepared from the PyC clinker was found to be consistent with those of the industrial cements e.g. CEM I type cements. It can be inferred from the leachability tests (TCLP and SPLP) that PyC could be a potential source of heavy metal pollution while the mortar samples obtained from the PyC clinkers present no environmental problems. These findings suggest that the waste pyrite cinders can be readily used as iron source for the production of Portland cement. The availability of PyC in large quantities at low cost provides further significant benefits for the management/environmental practices of these wastes and for the reduction of mining and processing costs of cement raw materials.

  13. Environmental Geochemistry and Acid Mine Drainage Evaluation of an Abandoned Coal Waste Pile at the Alborz-Sharghi Coal Washing Plant, NE Iran

    Energy Technology Data Exchange (ETDEWEB)

    Jodeiri Shokri, Behshad, E-mail: b.jodeiri@hut.ac.ir [Hamedan University of Technology (HUT), Department of Mining Engineering (Iran, Islamic Republic of); Doulati Ardejani, Faramarz [University of Tehran, School of Mining, College of Engineering (Iran, Islamic Republic of); Ramazi, Hamidreza [Amirkabir University of Technology (Tehran Polytechnic), Department of Mining and Metallurgical Engineering (Iran, Islamic Republic of)

    2016-09-15

    In this paper, an abandoned waste coal pile, which is resulted from Alborz-Sharghi coal washing plant, NE of Iran was mineralogically and geochemically characterized to evaluate pyrite oxidation, acid mine drainage (AMD) generation, and trace element mobility. After digging ten trenches and vertical sampling, a quantitative method including the atomic absorption test, and the quality-based methods including optical study were carried out for determination of pyrite fractions in the waste pile. The geochemical results revealed that the fraction of remaining pyrite increased with depth, indicating that pyrite oxidation is limited to the shallower depths of the pile which were confirmed by variations of sulfate, pH, EC, and carbonate with depth of the pile. To evaluate the trend of trace elements and mineralogical constituents of the waste particles, the samples were analyzed by using XRD, ICP-MS, and ICP-OES methods. The results showed the secondary and neutralizing minerals comprising gypsum have been formed below the oxidation zone. Besides, positive values of net neutralization potential indicated that AMD generation has not taken in the waste pile. In addition, variations of trace elements with depth reveal that Pb and Zn exhibited increasing trends from pile surface toward the bottom sampling trenches while another of them such as Cu and Ni had decreasing trends with increasing depth of the waste pile.

  14. Coal 95

    International Nuclear Information System (INIS)

    Sparre, C.

    1995-01-01

    The report deals with the use of coal and coke in Sweden during 1994. Some information about technology, environmental questions and markets are also given. Data have been collected by questionnaires to major users and by telephone to minor users. Preliminary statistical data from Statistics Sweden have also been used.The use of steam coal for heating purposes has been unchanged during 1994 at a level of 1 Mtons. The production in the cogeneration plants has been constant, but has increased for electricity production. The minor plants have increased their use of forest fuels. The use of steam coal will probably go down in the next years both for heat and cogeneration plants. During the top year 1987 coal was used in 18 hot water and 11 cogeneration plants. 1994 these figures are 3 and 12. Taxes and environmental reasons explain this trend. The use of steam coal in industry has been constant at the level 0.7 Mtons. The import of metallurgical coal in 1993 was 1.6 Mtons, like 1992. Import of 0.3 Mtons of coke gives the total consumption of coke in industry as 1.5 Mtons. the average price of steam coal imported to Sweden was 317 SEK/ton, 3% higher than 1993. All Swedish plants meet their emission limit of dust, SO 2 and NO x as given by county administrations or concession boards. The cogeneration plants all have some SO 2 removal system. The biggest cogeneration plant (Vaesteraas) has recently invested in a SCR NO x cleaning system. Most other plants use low NO x burners or SNR injection systems based on ammonia or urea. 2 figs, 13 tabs

  15. Management present situation and countermeasures of coal mines safety in production

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shu-dong; YU Chang-wu

    2008-01-01

    Analyzed of the present situation of Chinese coal mines safety in production and the reasons for coal mining accident, and realized the coal mines safety in production,which should increase the legal safeguards of coal mine safety in production, and safety input, established the comprehensive coal mine safety evaluation system, comprehensively enhance quality of coal mine workers, established and improved early warning mechanism of safety production of coal mine.

  16. Methodology used for the determination of physical and mechanical properties of crushed coal and new criteria for the selection of calculating parameters according to which coal bins in thermal power plants are dimensioned

    Energy Technology Data Exchange (ETDEWEB)

    Obradovic, R. [Mining Institute Belgrade, Belgrade (Yugoslavia)

    1997-07-01

    In order to acquire the data necessary for design engineering of coal bins in thermal power plants (TPP), an enhanced research method has been adopted, along with new criteria for the interpretation of the results obtained in the course of crushed coal testing, considering the shearing strength values and the expected elastic deformations of bin walls. The investigations presented in this paper have been carried out in the Thermal Power Plant - Nikola Tesla-B, (TPPNT) in Obrenovac, Yugoslavia. 6 refs., 1 tab.

  17. Research on desulfurisation of fine coal under compounding the physics force field

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Y.; Fu, D.; Tao, D.; Liu, J.; Zhao, Y. [China University of Mining and Technology, Xuzhou (China)

    2005-08-15

    Desulphurization experiment carried on under compounding the physics force field was described for -0.5 mm fine particle of high sulphur coal. The experiment factorial plan of desulphurization on centrifugal gravity Falcon separator was designed and its results were analyzed by using Design-Expert 6.0 software. The 2-reactor interaction relation model between comprehensive desulphurization efficiency of pyrite sulphur and different operation variable was drawn, i.e. 2 FI model, and the 2-factor interaction on pyrite desulphurization efficiency of the operation factors differently was analyzed. The interaction on pyrite desulphurization efficiency of feed rate and feed concentration is significant. The optimization test condition for desulphurization was proposed by Design-Expert 6.0, and comprehensive desulphurization efficiency of 86.90% can be achieved. 5 refs., 3 figs., 7 tabs.

  18. Production of hydroxyl radicals from abiotic oxidation of pyrite by oxygen under circumneutral conditions in the presence of low-molecular-weight organic acids

    Science.gov (United States)

    Zhang, Peng; Yuan, Songhu

    2017-12-01

    (II)-citrate- oxidation. Most soluble Fe3+ that is produced from pyrite oxidation hydrolyzes to Fe(III) hydroxide. Kinetic models that were developed according to the proposed mechanisms identified the relative importance of each reaction for radOH production. Using the kinetic model, the oxidation efficiencies of the redox-active substances that react with radOH at different reaction-rate constants were estimated in the presence of 1 mM citrate. This study presents on the overlooked role of LMWOAs in enhancing radOH production from pyrite oxidation by O2 in pyrite-rich circumneutral environments, such as marine and estuarine sediments and salt marshes.

  19. Particulate Pyrite Autotrophic Denitrification (PPAD) for Remediation of Nitrate-contaminated Groundwater

    Science.gov (United States)

    Tong, S.; Rodriguez-Gonzalez, L. C.; Henderson, M.; Feng, C.; Ergas, S. J.

    2015-12-01

    The rapid movement of human civilization towards urbanization, industrialization, and increased agricultural activities has introduced a large amount of nitrate into groundwater. Nitrate is a toxic substance discharged from groundwater to rivers and leads to decreased dissolved oxygen and eutrophication. For this experiment, an electron donor is needed to convert nitrate into non-toxic nitrogen gas. Pyrite is one of the most abundant minerals in the earth's crust making it an ideal candidate as an electron donor. The overall goal of this research was to investigate the potential for pyrite to be utilized as an electron donor for autotrophic denitrification of nitrate-contaminated groundwater. Batch studies of particulate pyrite autotrophic denitrification (PPAD) of synthetic groundwater (100 mg NO3--N L-1) were set up with varying biomass concentration, pyrite dose, and pyrite particle size. Reactors were seeded with mixed liquor volatile suspended solids (VSS) from a biological nitrogen removal wastewater treatment facility. PPAD using small pyrite particles (exhibited substantial nitrate removal rate, lower sulfate accumulation (5.46 mg SO42-/mg NO3--N) and lower alkalinity consumption (1.70 mg CaCO3/mg NO3--N) when compared to SOD (7.54 mg SO42-/mg NO3--N, 4.57 mg CaCO3/mg NO3--N based on stoichiometric calculation). This research revealed that the PPAD process is a promising technique for nitrate-contaminated groundwater treatment and promoted the utilization of pyrite in the field of environmental remediation.

  20. Coal preparation

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    The acid rain control legislation has prompted the Department of Energy (DOE) to seek new technology using the Clean Coal Technology program solicitation. The main goal of the program is to reduce SO 2 emissions below 9 Mt/a (10 million stpy) and NO x emission below 5.4 Mt/a (6 million stpy) by the year 2000. This would be accomplished by using precombustion, combustion, post combustion and conversion technology. Utilities are considering installing new scrubbers, switching fuel or possibly deep clean. However, the time required to implement the control technology is short. Due to the legislation, about 110 plants will have to adopt one of the approaches. This paper reports that in characterization of coal, Ames Laboratory used a scanning electron microscope- based, automated image analysis (SEM-AIA) technique to identify coal and mineral matter association. Various forms of organic sulfur were identified using peroxyacetic acid oxidation of coal. This was followed by subsequent microscopic, GC-MS, and HRMS analysis by Southern Illinois University. In ultrafine grinding of coal, it was reported by the Mining and Mineral Institute of Alabama that silica sand or flint shot used less energy compared to steel ball mills

  1. Technological procedure for chemical cleaning prior to re-pyritization of H2O-H2S isotopic exchange installations

    International Nuclear Information System (INIS)

    Stefanescu, I.; Smaranda, D.; Titescu, Gh.

    1996-01-01

    In normal operation the anti-corrosive shielding of the GS installations undergo a slow, irreversible degradation in time so that after 6 - 8 years their protection characteristics break down. In order to put them back in operation the regeneration of anti-corrosive is required. The procedure achieved at ICIS - Rm.Valcea consists in chemical cleaning of the impaired layers and re-pyritization of the interior surface of installations. Chemical cleaning include the following operations: - mechanical cleaning; - water washing; - alkaline washing with sodium hydroxide, tri-sodium phosphate and sodium tri-polyphosphate; - final mechanical cleaning; - neutralizing washing; - chemical cleaning with phosphoric acid solution; - neutralizing washing. After applying this procedure, the surface is prepared for the pyritization regeneration of the anti-corrosive shielding which ensures the prolongation of the equipment service lifetime with another six year period

  2. Carbonation-Induced Mineralogical Changes in Coal Mining Waste Blended Cement Pastes and Their Influence on Mechanical and Microporosity Properties

    Directory of Open Access Journals (Sweden)

    Moisés Frías

    2018-04-01

    Full Text Available The worldwide pursuit of new eco-efficient pozzolans is ongoing. Kaolinite-based waste is an eco-friendly source of recycled metakaolinite, a highly pozzolanic product. In this study, a blended cement paste containing 20% activated coal waste (ACW was exposed to a 100% CO2 atmosphere at 65% RH for 7 days. The variations in its phase composition and strength were studied and compared to an OPC control. Both pastes were cured for 28 days prior to the carbonation test. Reaction kinetics were assessed using XRD, SEM/EDX, TG/DTG, FT-IR, Micro-Raman spectroscopy, pore solution pH and the cumulative carbonated fraction. The blended cement carbonated 68% faster than the control. While portlandite carbonation was the main reaction in both cements, decalcification was also observed (more intensely in the 20% ACW paste in other hydraulic calcium phases (C-S-H gel, monocarboaluminate (C4AcH12, ettringite and tetracalcium aluminate (C4AH13. The end product of this reaction was calcium carbonate, mainly in the form of calcite, although traces of aragonite and amorphous carbonate were also detected. Compressive strength values rose with accelerated carbonation time and pore size reduction in both cement pastes.

  3. Biotoxicity assessment and toxicity mechanism on coal gasification wastewater (CGW): A comparative analysis of effluent from different treatment processes.

    Science.gov (United States)

    Ma, Weiwei; Han, Yuxing; Xu, Chunyan; Han, Hongjun; Zhu, Hao; Li, Kun; Zheng, Mengqi

    2018-05-04

    Even though coal gasification wastewater (CGW) treated by various biochemical treatment processes generally met the national discharge standard, its potential biotoxicity was still unknown. Therefore, in this study, bioassay with Tetrahymena thermophila (T. thermophila) was conducted to comprehensively evaluate the variation of biotoxicity in raw CGW and the treated effluent from lab-scale micro-electrolysis integrated with biological reactor (MEBR), single iron-carbon micro-electrolysis (ICME) and conventional activated sludge (CAS) processes. The results illustrated that raw CGW presented intensive acute toxicity with 24 h EC 50 value of 8.401% and toxic unit (TU) value of 11.90. Moreover, it performed significant cell membrane destruction and DNA damage even at 10% dilution concentration. The toxicant identification results revealed that multiple toxic polar compounds such as phenolic, heterocyclic and polycyclic aromatic compounds were the main contributors for biotoxicity. Furthermore, these compounds could accelerate oxidative stress, thereby inducing oxidative damage of cell membrane and DNA. As for treated effluent, TU value was decreased by 90.58% in MEBR process. An effective biotoxicity reduction was achieved in MEBR process owing to high removal efficiency in polar organic toxicants. In contrast, effluent from ICME and CAS processes presented relatively high acute toxicity and genotoxicity, because various heterocyclic and polycyclic aromatic compounds were difficult to be degraded in these processes. Therefore, it was suggested that MEBR was a potential and feasible process for improving CGW treatment and minimizing ecological risk. Copyright © 2018. Published by Elsevier B.V.

  4. Mechanical Properties of High Strength Concrete Containing Coal Bottom Ash and Oil-Palm Boiler Clinker as Fine Aggregates

    Directory of Open Access Journals (Sweden)

    Soofinajafi Mahmood

    2016-01-01

    Full Text Available This research aims to utilize Coal Furnace Bottom ash (CBA and Oil-Palm Boiler Clinker (OPBC as fine aggregate in concrete mix proportions. They are solid wastes from power plant and Oil Palm industry, respectively. Since these by-products do not have any primary use and are pure waste, an opportunity to use them as aggregate in concrete industry not only is economical but also will be an environmental friendly opportunity leading towards a more sustainable production chain. CBA and OPBC sands had similar grading to normal sand but have lower density and higher water absorption. In a high strength concrete, normal sand was replaced up to 25% with either CBA or OPBC. Test results showed that although water absorption of these wastes was more than normal sand but the slump value of concrete containing each of these wastes showed that these concretes had good workability. All mixes containing these wastes had slightly lower compressive strength at early ages and equivalent or higher compressive strength at later ages compared to control mix. The 28-day compressive strength of these concretes was in the range of 69–76 MPa which can be categorized as high strength concrete. In general, the performance of OPBC was better than CBA at 25% replacement level. However, it is recommended that at least 12.5% of total volume of fine aggregate in a high strength concrete is used of CBA or OPBC.

  5. Distilling coal

    Energy Technology Data Exchange (ETDEWEB)

    Blythe, F C

    1914-09-14

    In the destructive distillation of bituminous coal, heavy hydrocarbon oil, such as petroleum, kerosine, shale oil, and heavy tar oil, obtained in some cases during the process, is added to the coal, which is then distilled under pressure and at a comparatively low temperature regulated so as to produce a large proportion of hydrocarbon oils and a small proportion of permanent gas. In one method, about 5 to 10 parts of hydrocarbon oil are mixed with 100 parts of crushed or ground coal, and the mixture is heated in a closed vessel, provided in some cases with an agitator, under a pressure of about 60 lb/in/sup 2/, and the temperature may be gradually raised to 350/sup 0/C and then to about 500/sup 0/C. The heating may be by means of superheated steam with or without external heat.

  6. Adsorção de xantatos sobre pirita Adsorption of xanthate on pyrite

    Directory of Open Access Journals (Sweden)

    Fábio Garcia Penha

    2001-10-01

    Full Text Available This paper presents a study of adsorption of xanthate with alkyl chain of two (C2XK, four (C4XK and eight (C8XK atoms of carbon, on pyrite from Santa Catarina, Brazil. The results showed that pyrite surface changes from hydrophilic to hydrophobic when xanthate is adsorbed increasing the contact angle to 35º for C2XK, and to 90º for C4XK and C8XK. The rate of flotation of pyrite particles after adsorption increases with the increase of the number of carbon atoms in the alkyl chain in agreement with the results of contact angle measurements.

  7. Characterization of a coal tailing deposit for zero waste mine in the Brazilian coal field of Santa Catarina

    International Nuclear Information System (INIS)

    Amaral Filho, J.R.; Schneider, I.A.H.; Tubino, R.M.C.; Brum de, I.A.S.; Miltzarek, G.; Sampaio, C.H.

    2010-01-01

    Coal tailings deposits in Brazil are occupying large areas of land while also generating acid mine drainage (AMD) that includes heavy metals. This paper described an analytical study of a typical coal tailings deposit. The study objective was to separate low density, intermediate density, and high density fractions for future reuse. Particle size analysis, disymmetric studies, X-ray diffraction, and tests conducted to determine ash, total sulphur, and acid bases were conducted in order to characterize the coal tailings samples. Results of the study demonstrated a size distribution of 67 percent coarse, 14 percent fine, and 19 percent ultra-fine particles. The gravimetric concentration method was used to recover 34.2 percent of the total deposit for future energy use. Approximately 9.2 percent of the remaining deposit was a pyrite concentrate. The acid generating potential of the remaining materials was reduced by approximately 60 percent. 9 refs., 1 tab., 2 figs.

  8. Geochemical Characteristics of Trace Elements in the No. 6 Coal Seam from the Chuancaogedan Mine, Jungar Coalfield, Inner Mongolia, China

    Directory of Open Access Journals (Sweden)

    Lin Xiao

    2016-03-01

    Full Text Available Fourteen samples of No. 6 coal seam were obtained from the Chuancaogedan Mine, Jungar Coalfield, Inner Mongolia, China. The samples were analyzed by optical microscopic observation, X-ray diffraction (XRD, scanning electron microscope equipped with an energy-dispersive X-ray spectrometer (SEM-EDS, inductively coupled plasma mass spectrometry (ICP-MS and X-ray fluorescence spectrometry (XRF methods. The minerals mainly consist of kaolinite, pyrite, quartz, and calcite. The results of XRF and ICP-MS analyses indicate that the No. 6 coals from Chuancaogedan Mine are higher in Al2O3, P2O5, Zn, Sr, Li, Ga, Zr, Gd, Hf, Pb, Th, and U contents, but have a lower SiO2/Al2O3 ratio, compared to common Chinese coals. The contents of Zn, Sr, Li, Ga, Zr, Gd, Hf, Pb, Th, and U are higher than those of world hard coals. The results of cluster analyses show that the most probable carrier of strontium in the coal is gorceixite; Lithium mainly occurs in clay minerals; gallium mainly occurs in inorganic association, including the clay minerals and diaspore; cadmium mainly occurs in sphalerite; and lead in the No. 6 coal may be associated with pyrite. Potentially valuable elements (e.g., Al, Li, and Ga might be recovered as byproducts from coal ash. Other harmful elements (e.g., P, Pb, and U may cause environmental impact during coal processing.

  9. Role of non-ferrous coal minerals and by-product metallic wastes in coal liquefaction. Technical progress report, March 1, 1981-May 31, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Garg, D.; Givens, E.N.; Schweighardt, F.K.; Curtis, C.W.; Guin, J.A.; Huang, W.J.; Shridharani, K.

    1981-06-01

    This report covers results from both tubing-bomb experiments and continuous PDU runs. The following materials were evaluated in the PDU on Elkhorn No. 2 coal from Floyd County, Kentucky: Molybdic oxides; iron oxide; pyrite; pyrite/iron oxide mixture, and iron sulfate impregnation. A base case liquefaction run was also made for direct comparison. All of the above materials were examined at both 825 and 850/sup 0/F. Tubing-bomb experiments are reported on pyrite, red mud, sodium sulfide and organic compounds of cobalt, nickel, molybdenum, zinc, chromium and lead. Significant conclusions were drawn on the catalysis by different materials. Especially significant was the higher level of activity resulting from impregnation versus particle incorporation of the catalyst in the system. Impregnation of coal decreased the hydrocarbon gases yield and increased oil yield. Hydrogen consumption was significantly reduced by impregnation. Addition of molybdic oxide containing 90% MoO/sub 3/ and 10% silica to coal liquefaction reaction mixture had the following effect: coal conversion increased, oil yield increased by more than a factor of two at both temperatures, hydrogen consumption increased, solvent/oil fraction showed substantial increase in hydrogen content, and molybdenum in the resulting liquefaction residue was apparently transformed into an amorphous material. A more thorough evaluation of completely sulfided molybdenum will be made to see if its activity increases. In the tubing-bomb experiments organic compound of molybdenum showed the highest activity for coal conversion and oil production. Significant synergism was noted between red mud and sodium sulfide in the coal liquefaction reaction.

  10. Low temperature anaerobic bacterial diagenesis of ferrous monosulfide to pyrite

    Science.gov (United States)

    Donald, Ravin; Southam, Gordon

    1999-07-01

    In vitro enrichment cultures of dissimilatory sulfate-reducing bacteria precipitated FeS and catalyzed its transformation into FeS 2 at ambient temperature and pressure under anaerobic conditions. When compared to purely abiotic processes, the bacterially mediated transformation was shown to be more efficient in transforming FeS into FeS 2. This occurred due to the large, reactive surface area available for bacterially catalyzed diagenesis, where the biogenic FeS precursor was immobilized as a thin film (˜25 nm thick) on the μm-scale bacteria. The bacteria also contained the source(s) of sulfur for diagenesis to occur. Using a radiolabeled organic-sulfur tracer study, sulfur was released during cell autolysis and was immobilized at the bacterial cell surface forming FeS 2. The formation of FeS 2 occurred on both the inner and outer surfaces of the cell envelope and represented the first step of bacterial mineral diagenesis. Pyrite crystals, having linear dimensions of ˜1 μm, grew outward from the bacterial cell surfaces. These minerals were several orders of magnitude larger in volume than those originating abiotically.

  11. Biogeochemistry of pyrite and iron sulfide oxidation in marine sediments

    DEFF Research Database (Denmark)

    Schippers, A.; Jørgensen, BB

    2002-01-01

    as substrates and NO3- as electron acceptor, in the presence of (FeS2)-Fe-55, to test for co-oxidation of FeS2, but an anaerobic microbial dissolution of (FeS2)-Fe-55, could not been detected. FeS2 and FeS were not oxidized by amorphous Fe(III) oxide in the presence of Fe-complexing organic compounds......Pyrite (FeS2) and iron monosulfide (FeS) play a central role in the sulfur and iron cycles of marine sediments, They may be buried in the sediment or oxidized by O-2 after transport by bioturbation to the sediment surface. FeS2 and FeS may also be oxidized within the anoxic sediment in which NO3...... marine sediments and incubated at different temperatures for > 1 yr. Bacteria could not be enriched with FeS2 as substrate or with FeS and amorphous Fe(III) oxide. With FeS and NO3-, 14 enrichments were obtained. One of these enrichments was further cultivated anaerobically with Fe2+ and S-0...

  12. Copper-arsenic decoupling in an active geothermal system: A link between pyrite and fluid composition

    Science.gov (United States)

    Tardani, Daniele; Reich, Martin; Deditius, Artur P.; Chryssoulis, Stephen; Sánchez-Alfaro, Pablo; Wrage, Jackie; Roberts, Malcolm P.

    2017-05-01

    Over the past few decades several studies have reported that pyrite hosts appreciable amounts of trace elements which commonly occur forming complex zoning patterns within a single mineral grain. These chemical zonations in pyrite have been recognized in a variety of hydrothermal ore deposit types (e.g., porphyry Cu-Mo-Au, epithermal Au deposits, iron oxide-copper-gold, Carlin-type and Archean lode Au deposits, among others), showing, in some cases, marked oscillatory alternation of metals and metalloids in pyrite growth zones (e.g., of Cu-rich, As-(Au, Ag)-depleted zones and As-(Au, Ag)-rich, Cu-depleted zones). This decoupled geochemical behavior of Cu and As has been interpreted as a result of chemical changes in ore-forming fluids, although direct evidence connecting fluctuations in hydrothermal fluid composition with metal partitioning into pyrite growth zones is still lacking. In this study, we report a comprehensive trace element database of pyrite from the Tolhuaca Geothermal System (TGS) in southern Chile, a young and active hydrothermal system where fewer pyrite growth rims and mineralization events are present and the reservoir fluid (i.e. ore-forming fluid) is accessible. We combined the high-spatial resolution and X-ray mapping capabilities of electron microprobe analysis (EMPA) with low detection limits and depth-profiling capacity of secondary-ion mass spectrometry (SIMS) in a suite of pyrite samples retrieved from a ∼1 km drill hole that crosses the argillic (20-450 m) and propylitic (650-1000 m) alteration zones of the geothermal system. We show that the concentrations of precious metals (e.g., Au, Ag), metalloids (e.g., As, Sb, Se, Te), and base and heavy metals (e.g., Cu, Co, Ni, Pb) in pyrite at the TGS are significant. Among the elements analyzed, As and Cu are the most abundant with concentrations that vary from sub-ppm levels to a few wt.% (i.e., up to ∼5 wt.% As, ∼1.5 wt.% Cu). Detailed wavelength-dispersive spectrometry (WDS) X

  13. The role of sulfur-oxidizing bacteria Thiobacillus thiooxidans in pyrite weathering

    International Nuclear Information System (INIS)

    Sasaki, K.; Tsunekawa, M.; Ohtsuka, T.; Konno, H.

    1998-01-01

    The paper investigates the role of the sulfur-oxidizing bacteria Thiobacillus thiooxidans in pyrite weathering in order to clarify the effects of the bacteria on the dissolution behavior of pyrite and the formation of secondary minerals using Raman spectroscopy and powder X-ray diffraction (XRD) in addition to solution analysis. It was found that T. thiooxidans, when present with the iron-oxidizing bacteria Thiobacillus ferrooxidans, enhanced the dissolution of Fe and S species for pyrite, whereas T. thiooxidans alone did not oxidize pyrite. Enhancement of the consumption of elemental sulfur and regeneration of Fe(II) ions were also observed with T. thiooxidans together with T. ferrooxidans, while this did not occur with T. ferrooxidans alone

  14. Selective separation of arsenopyrite from pyrite by biomodulation in the presence of Acidithiobacillus ferrooxidans.

    Science.gov (United States)

    Chandraprabha, M N; Natarajan, K A; Somasundaran, P

    2004-08-15

    Effective methods for selective separation using flotation or flocculation of arsenopyrite from pyrite by biomodulation using Acidithiobacillus ferrooxidans are presented here. Adhesion of the bacterium to the surface of arsenopyrite was very slow compared to that to pyrite, resulting in a difference in surface modification of the minerals subsequent to interaction with cells. The cells were able to effectively depress pyrite flotation in presence of collectors like potassium isopropyl xanthate and potassium amyl xanthate. On the other hand the flotability of arsenopyrite after conditioning with the cells was not significantly affected. The activation of pyrite by copper sulfate was reduced when the minerals were conditioned together, resulting in better selectivity. Selective separation could also be achieved by flocculation of biomodulated samples.

  15. Effect of inversion layer at iron pyrite surface on photovoltaic device

    Science.gov (United States)

    Uchiyama, Shunsuke; Ishikawa, Yasuaki; Uraoka, Yukiharu

    2018-03-01

    Iron pyrite has great potential as a thin-film solar cell material because it has high optical absorption, low cost, and is earth-abundant. However, previously reported iron pyrite solar cells showed poor photovoltaic characteristics. Here, we have numerically simulated its photovoltaic characteristics and band structures by utilizing a two-dimensional (2D) device simulator, ATLAS, to evaluate the effects of an inversion layer at the surface and a high density of deep donor defect states in the bulk. We found that previous device structures did not consider the inversion layer at the surface region of iron pyrite, which made it difficult to obtain the conversion efficiency. Therefore, we remodeled the device structure and suggested that removing the inversion layer and reducing the density of deep donor defect states would lead to a high conversion efficiency of iron pyrite solar cells.

  16. Pyrite Iron Sulfide Solar Cells Made from Solution Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Law, Matt [Univ. of California, Irvine, CA (United States)

    2017-03-21

    This document summarizes research done under the SunShot Next Generation PV II project entitled, “Pyrite Iron Sulfide Solar Cells Made from Solution,” award number DE-EE0005324, at the University of California, Irvine, from 9/1/11 thru 11/30/16. The project goal was to develop iron pyrite (cubic FeS2) as an absorber layer for solution-processible p-n heterojunction solar cells with a pathway to >20% power conversion efficiency. Project milestones centered around seven main Tasks: (1) make device-quality pyrite thin-films from solar ink; (2) develop an ohmic bottom contact with suitable low resistivity; (3) produce a p-n heterojunction with VOC > 400 mV; (4) make a solar cell with >5% power conversion efficiency; (5) use alloying to increase the pyrite band gap to ~1.2-1.4 eV; (6) produce a p-n heterojunction with VOC > 500 mV; and finally (7) make a solar cell with >10% power conversion efficiency. In response to project findings, the Tasks were amended midway through the project to focus particular effort on passivating the surface of pyrite in order to eliminate excessively-strong surface band bending believed to be responsible for the low VOC of pyrite diodes. Major project achievements include: (1) development and detailed characterization of several new solution syntheses of high-quality thin-film pyrite, including two “molecular ink” routes; (2) demonstration of Mo/MoS2 bilayers as good ohmic bottom contacts to pyrite films; (3) fabrication of pyrite diodes with a glass/Mo/MoS2/pyrite/ZnS/ZnO/AZO layer sequence that show VOC values >400 mV and as high as 610 mV at ~1 sun illumination, although these high VOC values ultimately proved irreproducible; (4) established that ZnS is a promising n-type junction partner for pyrite; (5) used density functional theory to show that the band gap of pyrite can be increased from ~1.0 to a more optimal 1.2-1.3 eV by alloying with oxygen; (6) through extensive measurements of ultrahigh

  17. Bioenergetic studies of coal sulfur oxidation by extremely thermophilic bacteria. Final report, September 15, 1992--August 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, R.M.; Han, C.J.

    1997-12-31

    Thermoacidophilic microorganisms have been considered for inorganic sulfur removal from coal because of expected improvements in rates of both biotic and abiotic sulfur oxidation reactions with increasing temperature. In this study, the bioenergetic response of the extremely thermoacidophilic archaeon, Metallosphaera sedula, to environmental changes have been examined in relation to its capacity to catalyze pyrite oxidation in coal. Given an appropriate bioenergetic challenge, the metabolic response was to utilize additional amounts of energy sources (i.e., pyrite) to survive. Of particular interest were the consequences of exposing the organism to various forms of stress (chemical, nutritional, thermal, pH) in the presence of coal pyrite. Several approaches to take advantage of stress response to accelerate pyrite oxidation by this organism were examined, including attempts to promote acquired thermal tolerance to extend its functional range, exposure to chemical uncouplers and decouplers, and manipulation of heterotrophic and chemolithotrophic tendencies to optimize biomass concentration and biocatalytic activity. Promising strategies were investigated in a continuous culture system. This study identified environmental conditions that promote better coupling of biotic and abiotic oxidation reactions to improve biosulfurization rates of thermoacidophilic microorganisms.

  18. Exploratory research on solvent refined coal liquefaction. Annual technical progress report, January 1-December 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-09-01

    This report summarizes the progress of the Exploratory Research on Solvent Refined Coal Liquefaction project by The Pittsburg and Midway Coal Mining Co.'s Merriam Laboratory during 1979. In a series of experiments with varying feed gas composition, low levels (5 to 10 mole %) of carbon monoxide had little effect on the SRC II processing of Pittsburgh Seam coal (Powhatan No. 5 Mine) while higher levels (20 to 40 mole %) resulted in a general degradation of operability and reduced oil yields. Addition of finely divided (approx. 1 ..mu..m) pyrite to the reactive Powhatan coal had little effect on oil yields although the molecular weight of the distillation residue was apparently decreased. When finely divided pyrite and magnetite were added to the less reactive coals from the Loveridge and Blacksville No. 1 Mines (also Pittsburgh Seam), however, substantial increases in oil yields and product quality were obtained. In a comparison of upflow and downflow dissolver configurations with Powhatan coal in the SRC II mode, there was no difference in yields or product quality. A study characterizing specific reactors revealed a significantly higher conversion in the SRC I mode with a reactor approximating plug flow conditions compared to a completely backmixed reactor. In the SRC II mode there was only a slightly higher oil yield with the plug flow reactor.

  19. Mineral identification in Colombian coals using Moessbauer spectroscopy and X-ray diffraction

    International Nuclear Information System (INIS)

    Fajardo, M.; Mojica, J.; Barraza, J.; Perez Alcazar, G.A.; Tabares, J.A.

    1999-01-01

    Minerals were identified in three Colombian coal samples from the Southwest of the country using Moessbauer spectroscopy and X-ray diffraction. Original and sink separated coal fractions of specific gravity 1.40 and 1.60 with particle size less than 600 μm were used in the study. Using Moessbauer spectroscopy, the minerals identified in the original coal samples were pyrite jarosite, ankerite, illite and ferrous sulfate, whereas by means of X-ray diffraction, minerals identified were kaolinite, quartz, pyrite, and jarosite. Differences in mineral composition were found in the original and sink separated fractions using both techniques. Moessbauer spectra show that the mineral phases in low concentrations such as illite, ankerite and ferrous sulfate do not always appear in the spectra of sink coals, despite of those minerals occurring in the original coal, due to the fact that they are associated with the organic matter and not liberated in the grinding process. X-ray results show that the peak intensity grows as the specific gravity is increased indicating that the density separation method could be an effective process to clean coal

  20. The influence of reagent type on the kinetics of ultrafine coal flotation

    Science.gov (United States)

    Read, R.B.; Camp, L.R.; Summers, M.S.; Rapp, D.M.

    1989-01-01

    A kinetic study has been conducted to determine the influence of reagent type on flotation rates of ultrafine coal. Two ultrafine coal samples, the Illinois No. 5 (Springfield) and Pittsburgh No. 8, have been evaluated with various reagent types in order to derive the rate constants for coal (kc), ash (ka), and pyrite (kc). The reagents used in the study include anionic surfactants, anionic surfactant-alcohol mixtures, and frothing alcohols. In general, the surfactant-alcohol mixtures tend to float ultrafine coal at a rate three to four times faster than either pure alcohols or pure anionic surfactants. Pine oil, a mixture of terpene alcohols and hydrocarbons, was an exception to this finding; it exhibited higher rate constants than the pure aliphatic alcohols or other pure anionic surfactants studied; this may be explained by the fact that the sample of pine oil used (70% alpha-terpineol) acted as a frother/collector system similar to alcohol/kerosene. The separation efficiencies of ash and pyrite from coal, as evidenced by the ratios of kc/ka or kc/kp, tend to indicate, however, that commercially available surfactant-alcohol mixtures are not as selective as pure alcohols such as 2-ethyl-1-hexanol or methylisobutylcarbinol. Some distinct differences in various rate constants, or their ratios, were noted between the two coals studied, and are possibly attributable to surface chemistry effects. ?? 1989.

  1. Cu-As Decoupling in Hydrothermal Systems: A Link Between Pyrite Chemistry and Fluid Composition

    Science.gov (United States)

    Reich, M.; Tardani, D.; Deditius, A.; Chryssoulis, S.; Wrage, J.; Sanchez-Alfaro, P.; Andrea, H.; Cinthia, J.

    2016-12-01

    Chemical zonations in pyrite have been recognized in most hydrothermal ore deposit types, showing in some cases marked oscillatory alternation of metals and metalloids in pyrite growth zones (e.g., of Cu-rich, As-(Au)-depleted zones and As-(Au)-rich, Cu-depleted zones). This decoupled geochemical behavior of Cu and As has been interpreted as a result of chemical changes in ore-forming fluids, although direct evidence connecting fluctuations in hydrothermal fluid composition with metal partitioning into pyrite growth zones is still lacking. Here we report a comprehensive trace element database of pyrite from an active hydrothermal system, the Tolhuaca Geothermal System (TGS) in southern Chile. We combined high-spatial resolution and X-ray mapping capabilities of electron microprobe analysis (EMPA) with low detection limits and depth-profiling capabilities of secondary-ion mass spectrometry (SIMS) in a suite of pyrite samples retrieved from a 1 km drill hole that crosses the argillic and propylitic alteration zones of the geothermal system. We show that the concentrations of precious metals (e.g., Au, Ag), metalloids (e.g., As, Sb, Se, Te), and base and heavy metals (e.g., Cu, Co, Ni, Pb) in pyrite at the TGS are significant. Among the elements analyzed, arsenic, Cu and Co are the most abundant with concentrations that vary from sub-ppm levels to a few wt. %. Pyrites from the deeper propylitic zone do not show significant zonation and high Cu-(Co)-As concentrations correlate with each other. In contrast, well-developed zonations were detected in pyrite from the shallow argillic alteration zone, where Cu(Co)-rich, As-depleted cores alternate with Cu(Co)-depleted, As-rich rims. These microanalytical data were contrasted with chemical data of fluid inclusion in quartz veins (high Cu/Na and low As/Na) and borehole fluids (low Cu/Na and high As/Na) reported at the TGS, showing a clear correspondence between Cu and As concentrations in pyrite-forming fluids and chemical

  2. Coal Mines Security System

    OpenAIRE

    Ankita Guhe; Shruti Deshmukh; Bhagyashree Borekar; Apoorva Kailaswar; Milind E.Rane

    2012-01-01

    Geological circumstances of mine seem to be extremely complicated and there are many hidden troubles. Coal is wrongly lifted by the musclemen from coal stocks, coal washeries, coal transfer and loading points and also in the transport routes by malfunctioning the weighing of trucks. CIL —Coal India Ltd is under the control of mafia and a large number of irregularities can be contributed to coal mafia. An Intelligent Coal Mine Security System using data acquisition method utilizes sensor, auto...

  3. Coal at the crossroads

    International Nuclear Information System (INIS)

    Scaroni, A.W.; Davis, A.; Schobert, H.; Gordon, R.L.; Ramani, R.V.; Frantz, R.L.

    1992-01-01

    Worldwide coal reserves are very large but coal suffers from an image of being an environmentally unfriendly and inconvenient fuel. Aspects discussed in the article include: coal's poor image; techniques for coal analysis, in particular instrumented techniques; developments in clean coal technology e.g. coal liquefaction, fluidized bed combustion, co-generation and fuel slurries; the environmental impact of mining and land reclamation; and health aspects. It is considered that coal's future depends on overcoming its poor image. 6 photos

  4. Thermal stability and kinetics of decomposition of ammonium nitrate in the presence of pyrite

    International Nuclear Information System (INIS)

    Gunawan, Richard; Zhang Dongke

    2009-01-01

    The interaction between ammonium nitrate based industrial explosives and pyrite-rich minerals in mining operations can lead to the occurrence of spontaneous explosion of the explosives. In an effort to provide a scientific basis for safe applications of industrial explosives in reactive mining grounds containing pyrite, ammonium nitrate decomposition, with and without the presence of pyrite, was studied using a simultaneous Differential Scanning Calorimetry and Thermogravimetric Analyser (DSC-TGA) and a gas-sealed isothermal reactor, respectively. The activation energy and the pre-exponential factor of ammonium nitrate decomposition were determined to be 102.6 kJ mol -1 and 4.55 x 10 7 s -1 without the presence of pyrite and 101.8 kJ mol -1 and 2.57 x 10 9 s -1 with the presence of pyrite. The kinetics of ammonium nitrate decomposition was then used to calculate the critical temperatures for ammonium nitrate decomposition with and without the presence of pyrite, based on the Frank-Kamenetskii model of thermal explosion. It was shown that the presence of pyrite reduces the temperature for, and accelerates the rate of, decomposition of ammonium nitrate. It was further shown that pyrite can significantly reduce the critical temperature of ammonium nitrate decomposition, causing undesired premature detonation of the explosives. The critical temperature also decreases with increasing diameter of the blast holes charged with the explosive. The concept of using the critical temperature as indication of the thermal stability of the explosives to evaluate the risk of spontaneous explosion was verified in the gas-sealed isothermal reactor experiments.

  5. Thermal stability and kinetics of decomposition of ammonium nitrate in the presence of pyrite.

    Science.gov (United States)

    Gunawan, Richard; Zhang, Dongke

    2009-06-15

    The interaction between ammonium nitrate based industrial explosives and pyrite-rich minerals in mining operations can lead to the occurrence of spontaneous explosion of the explosives. In an effort to provide a scientific basis for safe applications of industrial explosives in reactive mining grounds containing pyrite, ammonium nitrate decomposition, with and without the presence of pyrite, was studied using a simultaneous Differential Scanning Calorimetry and Thermogravimetric Analyser (DSC-TGA) and a gas-sealed isothermal reactor, respectively. The activation energy and the pre-exponential factor of ammonium nitrate decomposition were determined to be 102.6 kJ mol(-1) and 4.55 x 10(7)s(-1) without the presence of pyrite and 101.8 kJ mol(-1) and 2.57 x 10(9)s(-1) with the presence of pyrite. The kinetics of ammonium nitrate decomposition was then used to calculate the critical temperatures for ammonium nitrate decomposition with and without the presence of pyrite, based on the Frank-Kamenetskii model of thermal explosion. It was shown that the presence of pyrite reduces the temperature for, and accelerates the rate of, decomposition of ammonium nitrate. It was further shown that pyrite can significantly reduce the critical temperature of ammonium nitrate decomposition, causing undesired premature detonation of the explosives. The critical temperature also decreases with increasing diameter of the blast holes charged with the explosive. The concept of using the critical temperature as indication of the thermal stability of the explosives to evaluate the risk of spontaneous explosion was verified in the gas-sealed isothermal reactor experiments.

  6. Application of fuel cell for pyrite and heavy metal containing mining waste

    Science.gov (United States)

    Keum, H.; Ju, W. J.; Jho, E. H.; Nam, K.

    2015-12-01

    Once pyrite and heavy metal containing mining waste reacts with water and air it produces acid mine drainage (AMD) and leads to the other environmental problems such as contamination of surrounding soils. Pyrite is the major source of AMD and it can be controlled using a biological-electrochemical dissolution method. By enhancing the dissolution of pyrite using fuel cell technology, not only mining waste be beneficially utilized but also be treated at the same time by. As pyrite-containing mining waste is oxidized in the anode of the fuel cell, electrons and protons are generated, and electrons moves through an external load to cathode reducing oxygen to water while protons migrate to cathode through a proton exchange membrane. Iron-oxidizing bacteria such as Acidithiobacillus ferrooxidans, which can utilize Fe as an electron donor promotes pyrite dissolution and hence enhances electrochemical dissolution of pyrite from mining waste. In this study mining waste from a zinc mine in Korea containing 17 wt% pyrite and 9% As was utilized as a fuel for the fuel cell inoculated with A. ferrooxidans. Electrochemically dissolved As content and chemically dissolved As content was compared. With the initial pH of 3.5 at 23℃, the dissolved As concentration increased (from 4.0 to 13 mg/L after 20 d) in the fuel cell, while it kept decreased in the chemical reactor (from 12 to 0.43 mg/L after 20 d). The fuel cell produced 0.09 V of open circuit voltage with the maximum power density of 0.84 mW/m2. Dissolution of As from mining waste was enhanced through electrochemical reaction. Application of fuel cell technology is a novel treatment method for pyrite and heavy metals containing mining waste, and this method is beneficial for mining environment as well as local community of mining areas.

  7. On the genesis of pyrite-polymetallic deposits of the Rudnyi Altai

    International Nuclear Information System (INIS)

    Puchkov, E.V.; Najdenov, B.M.

    1986-01-01

    Results of lead isotope composition measurements in pyrite-polymetallic deposits of the Rudnyi Altai are presented. Porphyr dating by zirconium has shown isochronous age of 552 million years. Lead of galenites of various generations and galenite form of lead of pyrit provide similar lead-isotope values with model age of 370 million years. The isotopic-geochemical data obtained are interpreted as applied to the deposit genesis

  8. The influence of pyrite on the solubility of minjingu and panda ...

    African Journals Online (AJOL)

    A laboratory study was conducted to investigate the effect of pyrite rock on the solubility of Minjingu and Panda phosphate rocks. The rocks were ground to 100 mesh (0.045 mm) after which each phosphate rock was mixed with pyrite at P:S ratios of 1:4, 1 :3, 1:2, 1:1, 2:1, and 3: 1. The mixtures were moistened and incubated ...

  9. Method to liquefy coal

    Energy Technology Data Exchange (ETDEWEB)

    Cronauer, D.C.; Kehl, W.L.

    1977-06-08

    In a method to liquify coal in the presence of hydrogen and hydrogen-transfer solvents, a hydrogenation catalyst is used in which an amorphous aluminium phosphate is taken as catalyst carrier. The particular advantage of aluminium phosphate catalyst carriers is their property of not loosing their mechanical strength even after manifold oxidizing regeneration (burning off the deposited carbon). The quantity of carbon deposited on the catalyst when using an aluminium phosphate carrier is considerably loss than with usual catalyst carriers.

  10. Application of fractal theory to top-coal caving

    International Nuclear Information System (INIS)

    Xie, H.; Zhou, H.W.

    2008-01-01

    The experiences of underground coal mining in China show that coal in a thick hard coal seam with a hard roof, the so-called 'double hard coal seam', is difficult to be excavated by top-coal caving technique. In order to solve the problem, a top-coal weakening technique is proposed in this paper. In the present study, fractal geometry provides a new description of the fracture mechanism for blasting. By means of theoretical analysis of the relationship between the fractal dimension of blasting fragments and the dynamite specific energy, a mechanical model for describing the size distribution of top-coal and the dissipation of blasting energy is proposed. The theoretical results are in agreement with laboratory and in situ test results. Moreover, it is shown that the fractal dimension of coal fragments can be used as an index for optimizing the blasting parameters for a top-coal weakening technique

  11. Super gene alternation of magnetite and pyrite and the role of their alternation products in the fixation of uranium from the circulating media. Vol. 3

    Energy Technology Data Exchange (ETDEWEB)

    El-Gemmizi, M A [Nuclear Materials Authority, Cairo, (Egypt)

    1996-03-01

    In most of the Egyptian altered radioactive granites, highly magnetic heavy particles were found to be radioactive. They are a mixture of several iron oxide minerals which are products of super gene alternation of the preexisting hypo gene iron-bearing minerals especially magnetite and pyrite. The end products of this super gene alternation are mainly hydrated iron oxide minerals limonite and/or goethite. During the alternation, deformation and defects in the mineral structure took place, thereby promoting diffusion of the substitutional and interstitial ions (uranium) towards these sites. The mechanism of the alternation of the hypo gene iron-bearing minerals, magnetite and pyrite to form the secondary mineral hematite, limonite and goethite; and the role of these secondary minerals in fixing uranium from the circulating media, and as indicators to the radioactivity of the host rocks are discussed. 2 figs.

  12. Super gene alternation of magnetite and pyrite and the role of their alternation products in the fixation of uranium from the circulating media. Vol. 3

    International Nuclear Information System (INIS)

    El-Gemmizi, M.A.

    1996-01-01

    In most of the Egyptian altered radioactive granites, highly magnetic heavy particles were found to be radioactive. They are a mixture of several iron oxide minerals which are products of super gene alternation of the preexisting hypo gene iron-bearing minerals especially magnetite and pyrite. The end products of this super gene alternation are mainly hydrated iron oxide minerals limonite and/or goethite. During the alternation, deformation and defects in the mineral structure took place, thereby promoting diffusion of the substitutional and interstitial ions (uranium) towards these sites. The mechanism of the alternation of the hypo gene iron-bearing minerals, magnetite and pyrite to form the secondary mineral hematite, limonite and goethite; and the role of these secondary minerals in fixing uranium from the circulating media, and as indicators to the radioactivity of the host rocks are discussed. 2 figs

  13. Pyrite oxidation in unsaturated aquifer sediments. Reaction stoichiometry and rate of oxidation

    DEFF Research Database (Denmark)

    Andersen, Martin Søgaard; Larsen, Flemming; Postma, Diederik Jan

    2001-01-01

    The oxidation of pyrite (FeS2) contained in unsaturated aquifer sediment was studied by sediment incubation in gas impermeable polymer laminate bags. Reaction progress was followed over a period of nearly 2 months by monitoring the gas composition within the laminate bag. The gas phase in the inc......The oxidation of pyrite (FeS2) contained in unsaturated aquifer sediment was studied by sediment incubation in gas impermeable polymer laminate bags. Reaction progress was followed over a period of nearly 2 months by monitoring the gas composition within the laminate bag. The gas phase...... in the incubation bags became depleted in O2 and enriched in CO2 and N2 and was interpreted as due to pyrite oxidation in combination with calcite dissolution. Sediment incubation provides a new method to estimate low rates of pyrite oxidation in unsaturated zone aquifer sediments. Oxidation rates of up to 9.4â10......-10 mol FeS2/gâs are measured, and the rates are only weakly correlated with the sediment pyrite content. The reactivity of pyrite, including the inhibition by FeOOH layers formed on its surface, apparently has a major effect on the rate of oxidation. The code PHREEQC 2.0 was used to calculate...

  14. Influence of the Interaction between Sphalerite and Pyrite on the Copper Activation of Sphalerite

    Directory of Open Access Journals (Sweden)

    Bo Yang

    2018-01-01

    Full Text Available In this paper, the effect of pyrite on the activation of sphalerite was investigated by micro-flotation, copper adsorption experiments, X-ray photoelectron spectroscopy (XPS, and electrochemical measurement. The micro-flotation test results showed that the recovery and flotation rate of sphalerite with copper sulphate as activator and butyl xanthate as collector were significantly decreased with the increasing content of pyrite in pulp. Cu2+ adsorption results indicated that the adsorption of Cu2+ on the sphalerite surface were decreased when pyrite was present in the pulp. XPS surface analysis demonstrated that the proportion of Cu+ species increased in the activation products on the sphalerite surface, but the total atomic concentration of Cu atom was decreased. Linear voltammetry measurement suggested that the current density of Cu+ species oxidizing to Cu2+ species was increased when sphalerite was electrically contacted with pyrite, which confirmed the increased proportion of Cu+ species on Cu-activation sphalerite surface when contacting with pyrite. These results indicated that there is not only a competitive adsorption for cupric ions (Cu2+, but the galvanic interaction between sphalerite and pyrite also has a significant influence on the copper activation of sphalerite.

  15. Spatial Mapping for Managing Oxidized Pyrite (FeS2 in South Sumatra Wetlands, Indonesia

    Directory of Open Access Journals (Sweden)

    M. Edi Armanto

    2016-02-01

    Full Text Available The research aimed to analyze spatial mapping for managing oxidized pyrite (FeS2 in South Sumatra wetlands, Indonesia. The field observations are done by exploring several transect on land units. The field description refers to Soil Survey Staff (2014. Water and soil samples were taken from selected key areas for laboratory analysis. The vegetation data was collected by making sample plots (squares method placed on each vegetation type with plot sizes depending on the vegetation type, namely 10 x 10 m for secondary forests and 5 x 5 m for shrubs and grass. The observations of surface water level were done during the river receding with units of m above sea level (m asl. The research results showed that pyrite formation is largely determined by the availability of natural vegetation as Sulfur (S donors, climate and uncontrolled water balance and supporting fauna such as crabs and mud shrimp.  Climate and water balance as well as supporting faunas is the main supporting factors to accelerate the process of pyrite formation. Oxidized pyrite serves to increase soil acidity, becomes toxic to fish ponds and arable soils, plant growth and disturbing the water and soil nutrient balances. Oxidized pyrite is predominantly accelerated by the dynamics of river water and disturbed natural vegetation by human activities.  The pyrite oxidation management approach is divided into three main components of technologies, namely water management, land management and commodity management.

  16. Radiation-thermal processes of conversion in the coals

    International Nuclear Information System (INIS)

    Mustafaev, I.I.

    2002-01-01

    effect in the generation of active hydrocarbons radicals from fuel oil, which play active role in the conversion of organic coal mass to the liquid and gas products. Under the optimal condition ( T=450 degrees centigrade, P=0,1 MPa, τ=20-25 minutes, (Rh/L)=3/1), up to 58% of the cleaned Yeni koy lignites converted to liquid and gaseous products. The fraction of liquid products of Co-pyrolysis of coals with oil fraction at optimal condition is determined. It is obvious that because of the destruction effect of the accelerated electron beam up to 19,2% liquid products are light fractions Tb 0 C. In these conditions, more than 55% sulphur content of the lignites is separated in the form of H 2 S and COS. b)Gasification: The radiation-thermal gasification reactions of various types of carbon (graphite, active coal and semi coke) with H 2 0 and CO 2 have been studied. The radiation effects are essential at the temperatures lower 500 degrees centigrade. It is connected to reactions of decomposition of gasified agents (H 2 O, CO 2 ) and intermediate products of their decomposition (OH, CO 2 * and other). Studies have been made of the formation of H 2 and CO at temperatures between 20 and 700 degrees centigrade on reacting graphite, activated carbon and semi coke with steam and carbon dioxide, respectively, in the presence of gamma radiation. The highest rates of H 2 and CO formation were observed on the gasification of semi coke. Investigation has been made of the temperature of semi coke production from lignite and also of the effect of preirradiation dose on the rate of CO formation in the semi coke/CO 2 system. An increase in the semi coke production temperature from 500 to 700 degrees centigrade reduced its reactivity with carbon dioxide by a factor of 1.4. Preirradiation of the semi coke with 200 kJ/kg decrease the reactivity by a factor of 2.8. A discussion is given of the mechanism of the effect of gamma-radiation on the gasification processes of different carbons in

  17. Coal industry annual 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-01

    Coal Industry Annual 1997 provides comprehensive information about US coal production, number of mines, prices, productivity, employment, productive capacity, and recoverable reserves. US Coal production for 1997 and previous years is based on the annual survey EIA-7A, Coal Production Report. This report presents data on coal consumption, coal distribution, coal stocks, coal prices, and coal quality for Congress, Federal and State agencies, the coal industry, and the general public. Appendix A contains a compilation of coal statistics for the major coal-producing States. This report includes a national total coal consumption for nonutility power producers that are not in the manufacturing, agriculture, mining, construction, or commercial sectors. 14 figs., 145 tabs.

  18. Coal industry annual 1997

    International Nuclear Information System (INIS)

    1998-12-01

    Coal Industry Annual 1997 provides comprehensive information about US coal production, number of mines, prices, productivity, employment, productive capacity, and recoverable reserves. US Coal production for 1997 and previous years is based on the annual survey EIA-7A, Coal Production Report. This report presents data on coal consumption, coal distribution, coal stocks, coal prices, and coal quality for Congress, Federal and State agencies, the coal industry, and the general public. Appendix A contains a compilation of coal statistics for the major coal-producing States. This report includes a national total coal consumption for nonutility power producers that are not in the manufacturing, agriculture, mining, construction, or commercial sectors. 14 figs., 145 tabs

  19. Sequential extraction of heavy metals in river sediments of an abandoned pyrite mining area: pollution detection and affinity series

    International Nuclear Information System (INIS)

    Pagnanelli, F.; Moscardini, E.; Giuliano, V.; Toro, L.

    2004-01-01

    In this paper heavy metal pollution at an abandoned Italian pyrite mine has been investigated by comparing total concentrations and speciation of heavy metals (Fe, Cu, Mn, Zn, Pb and As) in a red mud sample and a river sediment. Acid digestions show that all the investigated heavy metals present larger concentrations in the sediment than in the tailing. A modified Tessier's procedure has been used to discriminate heavy metal bound to organic fraction from those originally present in the mineral sulphide matrix and to detect a possible trend of metal mobilisation from red mud to river sediment. Sequential extractions on bulk and size fractionated samples denote that sediment samples present larger percent concentrations of the investigated heavy metals in the first extractive steps (I-IV) especially in lower dimension size fractionated samples suggesting that heavy metals in the sediment are significantly bound by superficial adsorption mechanisms. - Capsule: A modified Tessier's procedure, discriminating organic and sulphide bound metals, was used to detect pollutant mobilisation from red mud to river sediment in an abandoned pyrite mine

  20. Explanation for many of the unusual features of the massive sulfide deposits of the Iberian pyrite belt

    Science.gov (United States)

    Solomon, M.; Tornos, F.; Gaspar, O. C.

    2002-01-01

    Newly published fluid-inclusion data from quartz in stockwork veins beneath seven massive sulfide lenses in the Iberian pyrite belt suggest that the lenses were formed from fluids that on reaching the sea reversed buoyancy and ponded in basins. Sulfides quenched in the resulting brine pool would have settled to form a sulfide mud. This process provides a relatively efficient trapping mechanism for metal in the fluids and effectively excludes ambient seawater, accounting for the deposits tending to have the characteristics of large size, sheet-like form, absence of relict chimney structures, and a mineral content characterized by pyrite-arsenopyrite, and absence or scarcity of barite, marcasite, and Fe oxides. If total S was less than total metals in the stockwork fluids, some or all of the more soluble Zn and Pb could have been swept from the basin at the overflow, accounting for the variable but generally low Zn and Pb contents of the ores. The lack of sedimentary source for the high salinities implicates magmatic intrusions, possibly similar to those related to Sn-W mineralization.

  1. In situ phytoremediation of arsenic- and metal-polluted pyrite waste with field crops: effects of soil management.

    Science.gov (United States)

    Vamerali, Teofilo; Bandiera, Marianna; Mosca, Giuliano

    2011-05-01

    Sunflower, alfalfa, fodder radish and Italian ryegrass were cultivated in severely As-Cd-Co-Cu-Pb-Zn-contaminated pyrite waste discharged in the past and capped with 0.15m of unpolluted soil at Torviscosa (Italy). Plant growth and trace element uptake were compared under ploughing and subsoiling tillages (0.3m depth), the former yielding higher contamination (∼30%) in top soil. Tillage choice was not critical for phytoextraction, but subsoiling enhanced above-ground productivity, whereas ploughing increased trace element concentrations in plants. Fodder radish and sunflower had the greatest aerial biomass, and fodder radish the best trace element uptake, perhaps due to its lower root sensitivity to pollution. Above-ground removals were generally poor (maximum of 33mgm(-2) of various trace elements), with Zn (62%) and Cu (18%) as main harvested contaminants. The most significant finding was of fine roots proliferation in shallow layers that represented a huge sink for trace element phytostabilisation. It is concluded that phytoextraction is generally far from being an efficient management option in pyrite waste. Sustainable remediation requires significant improvements of the vegetation cover to stabilise the site mechanically and chemically, and provide precise quantification of root turnover. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Coal marketing manual 1987

    Energy Technology Data Exchange (ETDEWEB)

    1987-01-01

    This manual provides information on the international coal market in tabulated format. Statistics are presented for the Australian coal industry, exports, currency movements, world coal production, coal and coke imports and exports. Detailed information is provided on the Australian coal industry including mine specific summaries. Pricing summaries for thermal and coking coal in 1987, coal quality standards and specifications, trends in coal prices and stocks. Imports and exports for World coal and coke, details of shipping, international ports and iron and steel production. An exporters index of Australian and overseas companies with industry and government contacts is included. 15 figs., 67 tabs.

  3. Coal industry annual 1996

    International Nuclear Information System (INIS)

    1997-11-01

    This report presents data on coal consumption, coal distribution, coal stocks, coal prices, and coal quality, and emissions for Congress, Federal and State agencies, the coal industry, and the general public. Appendix A contains a compilation of coal statistics for the major coal-producing States.This report does not include coal consumption data for nonutility power producers that are not in the manufacturing, agriculture, mining, construction, or commercial sectors. Consumption for nonutility power producers not included in this report is estimated to be 24 million short tons for 1996. 14 figs., 145 tabs

  4. Coal industry annual 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-11-01

    This report presents data on coal consumption, coal distribution, coal stocks, coal prices, and coal quality, and emissions for Congress, Federal and State agencies, the coal industry, and the general public. Appendix A contains a compilation of coal statistics for the major coal-producing States.This report does not include coal consumption data for nonutility power producers that are not in the manufacturing, agriculture, mining, construction, or commercial sectors. Consumption for nonutility power producers not included in this report is estimated to be 24 million short tons for 1996. 14 figs., 145 tabs.

  5. Coal Industry Annual 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-10-01

    This report presents data on coal consumption, coal distribution, coal stocks, coal prices, coal quality, and emissions for Congress, Federal and State agencies, the coal industry, and the general public. Appendix A contains a compilation of coal statistics for the major coal-producing States. This report does not include coal consumption data for nonutility power producers that are not in the manufacturing, agriculture, mining, construction, or commercial sectors. Consumption for nonutility power producers not included in this report is estimated to be 21 million short tons for 1995.

  6. Coal Industry Annual 1995

    International Nuclear Information System (INIS)

    1996-10-01

    This report presents data on coal consumption, coal distribution, coal stocks, coal prices, coal quality, and emissions for Congress, Federal and State agencies, the coal industry, and the general public. Appendix A contains a compilation of coal statistics for the major coal-producing States. This report does not include coal consumption data for nonutility power producers that are not in the manufacturing, agriculture, mining, construction, or commercial sectors. Consumption for nonutility power producers not included in this report is estimated to be 21 million short tons for 1995

  7. Effect of Pyrite on Thiosulfate Leaching of Gold and the Role of Ammonium Alcohol Polyvinyl Phosphate (AAPP

    Directory of Open Access Journals (Sweden)

    Xiaoliang Liu

    2017-07-01

    Full Text Available The effect of pyrite and the role of ammonium alcohol polyvinyl phosphate (AAPP during gold leaching in ammoniacal thiosulfate solutions were investigated using pure gold foils. The results showed that pyrite catalyzed the decomposition and also significantly increased the consumption of thiosulfate. This detrimental effect became more severe with increasing pyrite content. Further, the presence of pyrite also substantially slowed the gold leaching kinetics and reduced the overall gold dissolution. The reduction in gold dissolution was found to be caused primarily by the surface passivation of the gold. The negative effects of pyrite, however, can be alleviated by the addition of AAPP. Comparison of zeta potentials of pyrite with and without AAPP suggests that AAPP had adsorbed on the surface of the pyrite and weakened the catalytic effect of pyrite on the thiosulfate decomposition by blocking the contact between the pyrite and thiosulfate anions. AAPP also competed with thiosulfate anions to complex with the cupric ion at the axial coordinate sites, and thus abated the oxidation of thiosulfate by cupric ions. Moreover, the indiscriminate adsorption of AAPP on the surfaces of gold and passivation species prevented the passivation of the gold surface by surface charge and electrostatic repulsion. Therefore, AAPP effectively stabilized the thiosulfate in the solution and facilitated the gold leaching in the presence of pyrite.

  8. Chalcopyrite Dissolution at 650 mV and 750 mV in the Presence of Pyrite

    Directory of Open Access Journals (Sweden)

    Yubiao Li

    2015-08-01

    Full Text Available The dissolution of chalcopyrite in association with pyrite in mine waste results in the severe environmental issue of acid and metalliferous drainage (AMD. To better understand chalcopyrite dissolution, and the impact of chalcopyrite’s galvanic interaction with pyrite, chalcopyrite dissolution has been examined at 75 °C, pH 1.0, in the presence of quartz (as an inert mineral and pyrite. The presence of pyrite increased the chalcopyrite dissolution rate by more than five times at Eh of 650 mV (SHE (Cu recovery 2.5 cf. 12% over 132 days due to galvanic interaction between chalcopyrite and pyrite. Dissolution of Cu and Fe was stoichiometric and no pyrite dissolved. Although the chalcopyrite dissolution rate at 750 mV (SHE was approximately four-fold greater (Cu recovery of 45% within 132 days as compared to at 650 mV in the presence of pyrite, the galvanic interaction between chalcopyrite and pyrite was negligible. Approximately all of the sulfur from the leached chalcopyrite was converted to S0 at 750 mV, regardless of the presence of pyrite. At this Eh approximately 60% of the sulfur associated with pyrite dissolution was oxidised to S0 and the remaining 40% was released in soluble forms, e.g., SO42−.

  9. Coal and Energy.

    Science.gov (United States)

    Bryant, Reba; And Others

    This teaching unit explores coal as an energy resource. Goals, student objectives, background information, and activity options are presented for each major section. The sections are: (1) an introduction to coal (which describes how and where coal was formed and explains the types of coal); (2) the mining of coal (including the methods and ways of…

  10. Application of Moessbauer spectroscopy for: (1) characterization of Egyptian Maghara coal; (2) evaluating the efficiency of different methods for coal desulphurization

    International Nuclear Information System (INIS)

    Eissa, N.A.; Sheta, N.H.; Ahmed, M.A.

    1992-01-01

    Coal has been recently discovered in Maghara mine at Northern Sinai, Egypt. Coal samples have been collected from different depths and were measured by XRD, XRF, and MS, in order to characterize this type of coal. It has been found that the iron bearing minerals are mainly pyrite and different sulphates depending on the depth of the sample. The second part contains the application of desulphurization techniques to Egyptian coal which are: floatation (one step and two steps), chemical [(HCl+HNO 3 ), and Fe 2 (SO 4 ) 3 ] and bacterial methods (Chromatium and Chlorobium species). The efficiency of each technique was calculated. A comparative discussion is given of each desulphurization method, from which the bacterial method has proved to be the most efficient one. (orig.)

  11. Oxy-coal Combustion Studies

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, J. [Univ. of Utah, Salt Lake City, UT (United States); Eddings, E. [Univ. of Utah, Salt Lake City, UT (United States); Lighty, J. [Univ. of Utah, Salt Lake City, UT (United States); Ring, T. [Univ. of Utah, Salt Lake City, UT (United States); Smith, P. [Univ. of Utah, Salt Lake City, UT (United States); Thornock, J. [Univ. of Utah, Salt Lake City, UT (United States); Y Jia, W. Morris [Univ. of Utah, Salt Lake City, UT (United States); Pedel, J. [Univ. of Utah, Salt Lake City, UT (United States); Rezeai, D. [Univ. of Utah, Salt Lake City, UT (United States); Wang, L. [Univ. of Utah, Salt Lake City, UT (United States); Zhang, J. [Univ. of Utah, Salt Lake City, UT (United States); Kelly, K. [Univ. of Utah, Salt Lake City, UT (United States)

    2012-01-06

    The objective of this project is to move toward the development of a predictive capability with quantified uncertainty bounds for pilot-scale, single-burner, oxy-coal operation. This validation research brings together multi-scale experimental measurements and computer simulations. The combination of simulation development and validation experiments is designed to lead to predictive tools for the performance of existing air fired pulverized coal boilers that have been retrofitted to various oxy-firing configurations. In addition, this report also describes novel research results related to oxy-combustion in circulating fluidized beds. For pulverized coal combustion configurations, particular attention is focused on the effect of oxy-firing on ignition and coal-flame stability, and on the subsequent partitioning mechanisms of the ash aerosol.

  12. Recrystallization Experiments of Pyrite From Circulating Hydrothermal Solution by Thermal Convection

    Science.gov (United States)

    Tanaka, K.; Isobe, H.

    2005-12-01

    Pyrite is one of the most common accessory minerals in many rocks and generally occurs in hydrothermal deposit. However, pyrite morphology and association with other sulfide minerals is not well known with respect to the solution condition, especially with the hydrothermal solution under circulation. In this study, recrystallization experiments of pyrite from circulating hydrothermal solution by thermal convection were carried out. A rectangular circuit (42.6 cm by 17.3 cm) of SUS316 pressure tubing with 5 mm in inner diameter was used as a reaction vessel. The volume of the circuit is approximately 24 ml. Long sides of the rectangular circuit were held to be 20 degrees inclination. One of the long sides was heated by an electric furnace. Solution in the circuit evaporates in the high temperature tubing and the vapor condenses in room temperature tubing. The solution backs to the bottom of the high temperature tubing. Thus, thermal convection of the solution produces circulation in the circuit. Starting material was filled in the high temperature tubing. The lower half was filled with mixture of 2 g of powdered natural pyrite and 4 g of quartz grains. The upper half was filled with quartz grains only. 9 ml of 5 mol/l NH4Cl solution was sealed in the circuit with the starting material. Temperature gradient of the sample was monitored by 6 thermocouples. Maximum temperature was controlled at 350°C. Experimental durations are 3, 5, 10 and 30 days. After the experiments, the run products are fixed with resin and cut every 2 cm. Thin sections of vertical cross-sections are made and observed by microscope and SEM. Tiny pyrite crystals occurred at the upper outside of the furnace, where temperature should be much lower than 200°C. In the lower half of the starting material, pyrite decomposed and pyrrhotite formed around pyrite grains. At higher temperature area, pyrite decomposition and pyrrhotite formation is remarkable. Circulating sulfur-bearing solution provided by

  13. Geochemical evolution of acidic ground water at a reclaimed surface coal mine in western Pennsylvania

    Science.gov (United States)

    Cravotta,, Charles A.

    1991-01-01

    Concentrations of dissolved sulfate and acidity in ground water increase downflow in mine spoil and underlying bedrock at a reclaimed surface coal mine in the bituminous field of western Pennsylvania. Elevated dissolved sulfate and negligible oxygen in ground water from bedrock about 100 feet below the water table suggest that pyritic sulfur is oxidized below the water table, in a system closed to oxygen. Geochemical models for the oxidation of pyrite (FeS2) and production of sulfate (SO42-) and acid (H+) are presented to explain the potential role of oxygen (O2) and ferric iron (Fe3+) as oxidants. Oxidation of pyrite by O2 and Fe3+ can occur under oxic conditions above the water table, whereas oxidation by Fe3+ also can occur under anoxic conditions below the water table. The hydrated ferric-sulfate minerals roemerite [Fe2+Fe43+(SO4)4·14H2O], copiapite [Fe2+Fe43+(SO4)6(OH)2·20H20], and coquimbite [Fe2(SO4)3·9H2O] were identified with FeS2 in coal samples, and form on the oxidizing surface of pyrite in an oxic system above the water table. These soluble ferric-sulfate 11 salts11 can dissolve with recharge waters or a rising water table releasing Fe3+, SO42-. and H+, which can be transported along closed-system ground-water flow paths to pyrite reaction sites where O2 may be absent. The Fe3+ transported to these sites can oxidize pyritic sulfur. The computer programs WATEQ4F and NEWBAL were used to compute chemical speciation and mass transfer, respectively, considering mineral dissolution and precipitation reactions plus mixing of waters from different upflow zones. Alternative mass-balance models indicate that (a) extremely large quantities of O2, over 100 times its aqueous solubility, can generate the observed concentrations of dissolved SO42- from FeS2, or (b) under anoxic conditions, Fe3+ from dissolved ferric-sulfate minerals can oxidize FeS2 along closed-system ground-water flow paths. In a system open to O2, such as in the unsaturated zone, the aqueous

  14. New method for reduction of burning sulfur of coal

    International Nuclear Information System (INIS)

    Lyutskanov, L.; Dushanov, D.

    1998-01-01

    The coal pyrolysis is key phase in the the pyrolysis-combustion cycle as it provides char for combustor. The behaviour of sulfur compounds during coal pyrolysis depends on factors as rank of coal, quantity of sulfur and sulfur forms distribution in the coal, quantity and kind of mineral matter and the process conditions. The mineral content of coal may inhibit or catalyze the formation of volatile sulfur compounds. The pyrolysis itself is a mean of removing inorganic and organic sulfur but anyway a portion of it remains in the char while the other moves into the tar and gas. The aim of this study was to determine an optimal reduction of burning sulfur at the coal pyrolysis by varying parametric conditions. The pyrolysis of different kinds of coal has been studied. The samples with size particles o C at atmospheric pressure and with a heating rate of 6-50 o C min -1 . They were treated with exhaust gas and nitrogen at an addition of steam and air. The char obtained remains up to 10 min at the final temperature. The char samples cool without a contact with air. Two methods of desulfurization-pyrolysis were studied - using 9-vertical tubular reactor and 9-horizontal turning reactor. The results obtained show that at all samples there is a decrease of burning sulfur with maximal removal efficiency 83%. For example at a pyrolysis of Maritsa Iztok lignite coal the burning sulfur is only 16% in comparison with the control sample. The remained is 90% sulfate, 10% organic and pyrite traces when a mixture 'exhaust gas-water stream-air' was used. The method of desulfurization by pyrolysis could be applied at different kinds of coal and different conditions. Char obtained as a clean product can be used for generating electric power. This innovation is in a stage of patenting

  15. Theoretical growth of framboidal and sunflower pyrite using the R-package frambgrowth

    Science.gov (United States)

    Merinero, Raul; Cárdenes, Víctor

    2017-12-01

    Framboids and sunflowers are the most ubiquitous shapes of sedimentary pyrite. Framboids are spherical aggregates of nanocrystals, while sunflowers are formed by overgrowth of framboids and represent intermediate stages in the transformation of framboids into euhedrae. The characterization of the size populations of these shapes provides critical information about the paleoredox conditions at time of formation and the subsequent changes in these conditions. This paper describes in detail an algorithm designed to model the growth and generate significant populations of both framboids and sunflowers, using functions of the statistical software R. The source code is provided as supplementary material to this paper. The algorithm uses several growth mechanisms based on dependence on or independence of the number of nanocrystals for framboids and the external diameter for sunflowers. Variability in the generated size populations depends on several parameters of the algorithm, such as the diameter of the nanocrystals, the initial diameter of the framboids and the maximum value of the random numbers. The resulting populations of framboids and sunflowers can be compared with data obtained from analysis of real samples in order to understand and model the genetic paleo-processes.

  16. Ore prospecting in the Iberian Pyrite Belt using seismic and potential-field data

    International Nuclear Information System (INIS)

    Carvalho, João; Pinto, Carlos; Sousa, Pedro; Matos, João Xavier

    2011-01-01

    Ore prospecting using gravimetric and magnetic data has become one of the traditional approaches used in past decades, often complemented with electric and electromagnetic methods. However, due to the problem of non-uniqueness inherent to potential-field modelling, constraints provided by structural methods such as seismic reflection are often used. During the exploration of polymetallic massive sulfide minerals in the Iberian Pyrite Belt, Figueira de Cavaleiros sector, located in the Sado Tertiary Basin, several gravimetric and magnetic anomalies were considered to be interesting targets. In order to reduce any ambiguity in the gravimetric modelling and to confirm the geological model of the area, two seismic reflection profiles were acquired. The interpretation of these profiles was assisted by three mechanical boreholes, two of which were located in the research area to make a seismostratigraphic interpretation. Unfortunately, the gravimetric modelling suggests that the anomaly has a lithological and structural origin and is not related to massive sulfides. Nevertheless, a good agreement between the seismic and potential-field data was achieved and new insights into the geological model for the region were obtained from this work, with accurate data about the Tertiary cover and Palaeozoic basement

  17. Coal -94

    International Nuclear Information System (INIS)

    Sparre, C.

    1994-05-01

    This report deals with use of coal and coke during 1993; information about techniques, environmental questions and markets are also given. Use of steamcoal for heating purposes has been reduced about 3 % during 1993 to 1,0 mill tons. This is the case especially for the heat generating boilers. Production in co-generation plants has been constant and has increased for electricity production. Minor plants have increased their use of forest fuels, LPG and NG. Use of steamcoal will probably go down in the immediate years both in heat generating and co-generating plants. Coal-based electricity has been imported from Denmark during 1993 corresponding to about 400 000 tons of coal, when several of our nuclear plants were stopped. Use of steamcoal in the industry has been constant at 700 000 tons. This level is supposed to be constant or to vary with business cycles. The import of metallurgical coal in 1993 was 1,6 mill tons like the year before. 1,2 mill tons coke were produced. Coke consumption in industry was 1,4 mill tons. 0,2 mill tons of coke were imported. Average price of steamcoal imported to Sweden in 1993 was 308 SEK/ton or 13 % higher than in 1992; this can be explained by the dollar price level increasing 34% in 1993. For the world, the average import price was 50,0 USD/ton, a decrease of 6 %. The coal market during 1993 was affected by less consumption in Europe, shut downs of European mines and decreasing prices. High freight price raises in Russia has affected the Russian export and the market in northern Europe. The prices have been stabilized recently. All Swedish plants meet emission limits of dust, SO 2 and NO x . Co-generation plants all have some sort of SO 2 -removal system; the wet-dry method is mostly used. A positive effect of the recently introduced NO x -duties is a 40% reduction

  18. Coal statistics 1977

    Energy Technology Data Exchange (ETDEWEB)

    Statistical Office of the European Communities

    1978-01-01

    Presents tables of data relating to the coal market in the European Community in 1977. The tables cover hard coal production, supply and trade; briquettes; cokes; lignite, brown coal briquettes and peat; and mines and coke ovens.

  19. Australian coal yearbook 1989

    Energy Technology Data Exchange (ETDEWEB)

    Aylward, A [ed.

    1989-01-01

    This yearbook contains a mine directory; details of coal export facilities and ports; annual coal statistics; a buyers' guide; names and addresses of industry organisations and an index of coal mine owners.

  20. Coal industry annual 1993

    Energy Technology Data Exchange (ETDEWEB)

    1994-12-06

    Coal Industry Annual 1993 replaces the publication Coal Production (DOE/FIA-0125). This report presents additional tables and expanded versions of tables previously presented in Coal Production, including production, number of mines, Productivity, employment, productive capacity, and recoverable reserves. This report also presents data on coal consumption, coal distribution, coal stocks, coal prices, coal quality, and emissions for a wide audience including the Congress, Federal and State agencies, the coal industry, and the general public. In addition, Appendix A contains a compilation of coal statistics for the major coal-producing States. This report does not include coal consumption data for nonutility Power Producers who are not in the manufacturing, agriculture, mining, construction, or commercial sectors. This consumption is estimated to be 5 million short tons in 1993.

  1. Coal industry annual 1993

    International Nuclear Information System (INIS)

    1994-01-01

    Coal Industry Annual 1993 replaces the publication Coal Production (DOE/FIA-0125). This report presents additional tables and expanded versions of tables previously presented in Coal Production, including production, number of mines, Productivity, employment, productive capacity, and recoverable reserves. This report also presents data on coal consumption, coal distribution, coal stocks, coal prices, coal quality, and emissions for a wide audience including the Congress, Federal and State agencies, the coal industry, and the general public. In addition, Appendix A contains a compilation of coal statistics for the major coal-producing States. This report does not include coal consumption data for nonutility Power Producers who are not in the manufacturing, agriculture, mining, construction, or commercial sectors. This consumption is estimated to be 5 million short tons in 1993

  2. Oxidation state of gold and arsenic in gold-bearing arsenian pyrite

    Energy Technology Data Exchange (ETDEWEB)

    Simon, G.; Huang, H.; Penner-Hahn, J.E.; Kesler, S.E.; Kao, L.S. [Univ. of Michigan, Ann Arbor, MI (United States)

    1999-07-01

    XANES measurements on gold-bearing arsenian pyrite from the Twin Creeks Carlin-type gold deposits show that gold is present as both Au{sup 0} and Au{sup 1+} and arsenic is present as As{sup 1{minus}}. Au{sup 0} is attributed to sub-micrometer size inclusions of free gold, whereas Au{sup 1+} is attributed to gold in the lattice of the arsenian pyrite. STEM observations suggest that As{sup 1{minus}} is probably concentrated in angstrom-scale, randomly distributed layers with a marcasite or arsenopyrite structure. Ionic gold (Au{sup 1+}) could be concentrated in these layers as well, and is present in both twofold- and fourfold-coordinated forms, with fourfold-coordinated Au{sup 1+} more abundant. Twofold-coordinated Au{sup 1+} is similar to gold in Au{sub 2}S in which it is linearly coordinated to two sulfur atoms. The nature of fourfold-coordinated Au{sup 1+} is not well understood, although it might be present as an Au-As-S compound where gold is bonded in fourfold coordination to sulfur and arsenic atoms, or in vacancy positions on a cation site in the arsenian pyrite. Au{sup 1+} was probably incorporated into arsenian pyrite by adsorption onto pyrite surfaces during crystal growth. The most likely compound in the case of twofold-coordinated Au{sup 1+} was probably a tri-atomic surface complex such as S{sub pyrite}-Au{sup 1+}-S{sub bi-sulfide}H or Au{sup 1+}-S-Au{sup 1+}. The correlation between gold and arsenic might be related to the role of arsenic in enhancing the adsorption of gold complexes of this type on pyrite surfaces, possibly through semiconductor effects.

  3. Australian black coal statistics 1990

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    This second edition of Australian black coal statistics replaces the Joint Coal Board's publication 'Black coal in Australia'. It includes an expanded international coal trade supplement. Sections cover resources of black coal, coal supply and demand, coal production, employment and productivity of mines, export data, coal consumption and a directory of producers.

  4. Volcanic ash in feed coal and its influence on coal combustion products

    Energy Technology Data Exchange (ETDEWEB)

    Brownfield, M.E.; Affolter, R.H.; Cathcart, J.D.; Brownfield, I.K.; Hower, J.C.; Stricker, G.D.; O' Connor, J.T.

    2000-07-01

    The US Geological Survey and the University of Kentucky Center for Applied Energy Research are collaborating with an Indiana Utility to determine the physical and chemical properties of feed coal and coal combustion products (CCPs) from a coal-fired power plant. The plant utilizes a low-sulfur (.23--.47 weight percent S) coal from the Powder River Basin, Wyoming. Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analysis of feed coal samples identified two mineral suites. A primary suite (not authigenic) consisting of quartz (detrital and volcanic beta-form grains), biotite, and minor zircon and a secondary authigenic mineral suite containing calcite, alumino-phosphates (crandallite and gorceixite), kaolinite, quartz, anatase, barite, and pyrite. The authigenic minerals are attributed to air-fall and reworked volcanic ash that was deposited in peat-forming mires. The Powder River Basin feed coals contain higher amounts of Ba, Ca, Mg, Na, Sr, and P compared to other analyzed eastern coals. These elements are associated with alumino-phosphate, biotite, calcite, and clay minerals. The element associations are indicative of coal that incorporated volcanic ash during deposition. XRD analysis of CCPs revealed a predominance of glass, perovskite, lime, gehlenite, quartz, and phosphates with minor amounts of periclase, anhydrite, hematite, and spinel group minerals in the fly ash; and quartz, plagioclase (albite and anorthite), pyroxene (augite and fassaite), rhodonite, and akermanite in the bottom ash. Microprobe and SEM analysis of fly ash samples revealed quartz, zircon, monazite, euhedral laths of corundum with merrillite, hematite, dendritic spinels/ferrites, and rounded grains of wollastonite with periclase. The abundant Ca and Mg mineral phases in the fly ashes are related to the presence of carbonate, clay, and phosphate minerals in the feed coal. The Ca- and Mg-rich mineral phases in the CCPs can be attributed to volcanic minerals deposited in the

  5. Experimental study on the mechanism of SO2 emission and calcium-based desulfurization in the coal oxygen-enriched combustion

    International Nuclear Information System (INIS)

    Tian, Luning; Chen, Hanping; Yang, Haiping; Wang, Xianhua; Zhang, Shihong

    2010-01-01

    Full text: The emission of SO 2 , CO 2 brings serious harm to the ecological environment, human health and the global climate change. The largest source of SO 2 , CO 2 is the combustion of fossil fuels for power generation. So developing the new technology for controlling pollutants emissions from coal combustion was imperative. Oxygen-enriched combustion technology is such a new technology which can realize CO 2 zero emission, enhance the combustion efficiency and reduce pollutants emission. Due to the high concentration of CO 2 , it has many different aspects in the SO 2 emission and calcium-based desulfurization compare with the conventional combustion. In this article, experiments have been done to investigate the behavior and mechanism of SO 2 emissions and removal in oxygen-enriched combustion. First, in TGA and fixed bed reactor, the SO 2 emission characteristics were investigated under various bed temperature, particle size and O 2 / CO 2 concentration. It was observed that SO 2 released faster and the emission peak was higher than air atmosphere. SO 2 emission concentration increased with the reaction temperature increasing. Simultaneously, the mechanism of SO 2 emission was obtained by analyzing the sulfur compounds in the gas products and solid products in different reaction times. Then, the impacts of reaction temperature, particle size, O 2 / CO 2 concentration and SO 2 concentration etc. on the efficiency of SO 2 removal were analyzed. The phase analysis, pore diameter distribution and microstructure of the solid product were investigated. The experimental results showed that the sulphur capture takes place by direct sulphation reaction at high CO 2 concentration which attributes to light sinter, better porous structure, higher optimal desulfurization temperature and high desulfurization efficiency of calcium-based sorbent. (author)

  6. 1982 Australian coal conference papers

    Energy Technology Data Exchange (ETDEWEB)

    1982-01-01

    This third Australian coal conference included papers discussing the market for coal, finance and investment, use of computers, mining, coal research, coal preparation and waste disposal, marketing and trade, and the transport of coal. All papers have been individually abstracted.

  7. Briquetting of Coke-Brown Coal Mixture

    Directory of Open Access Journals (Sweden)

    Ïurove Juraj

    1998-09-01

    Full Text Available The paper presents the results of the research of briquetting a coke-brown coal composite The operation consists of the feeding crushed coal and coke to moulds and pressing into briquettes which have been made in the Laboratories at the Mining Faculty of Technical University of Košice (Slovakia. In this research, all demands will be analyzed including the different aspects of the mechanical quality of briquettes, the proportion of fine pulverulent coal and coke in bricks, the requirements for briquetting the coke-brown coal materials.

  8. Rosebud syncoal partnership SynCoal{sup {reg_sign}} demonstration technology development update

    Energy Technology Data Exchange (ETDEWEB)

    Sheldon, R.W. [Rosebud SynCoal Company, Billings, MT (United States); Heintz, S.J. [Department of Energy, Pittsburgh, PA (United States)

    1995-12-01

    Rosebud SynCoal{reg_sign} Partnership`s Advanced Coal Conversion Process (ACCP) is an advanced thermal coal upgrading process coupled with physical cleaning techniques to upgrade high moisture, low-rank coals to produce a high-quality, low-sulfur fuel. The coal is processed through two vibrating fluidized bed reactors where oxygen functional groups are destroyed removing chemically bound water, carboxyl and carbonyl groups, and volatile sulfur compounds. After thermal upgrading, the SynCoal{reg_sign} is cleaned using a deep-bed stratifier process to effectively separate the pyrite rich ash. The SynCoal{reg_sign} process enhances low-rank western coals with moisture contents ranging from 2555%, sulfur contents between 0.5 and 1.5 %, and heating values between 5,500 and 9,000 Btu/lb. The upgraded stable coal product has moisture contents as low as 1 %, sulfur contents as low as 0.3%, and heating values up to 12,000 Btu/lb.

  9. Waterberg coal characteristics and SO2 minimum emissions standards in South African power plants.

    Science.gov (United States)

    Makgato, Stanford S; Chirwa, Evans M Nkhalambayausi

    2017-10-01

    Key characteristics of coal samples from the supply stock to the newly commissioned South African National Power Utility's (Eskom's) Medupi Power Station - which receives its supply coal from the Waterberg coalfield in Lephalale (Limpopo Province, South Africa) - were evaluated. Conventional coal characterisation such as proximate and ultimate analysis as well as determination of sulphur forms in coal samples were carried out following the ASTM and ISO standards. Coal was classified as medium sulphur coal when the sulphur content was detected in the range 1.15-1.49 wt.% with pyritic sulphur (≥0.51 wt.%) and organic sulphur (≥0.49 wt.%) accounted for the bulk of the total sulphur in coal. Maceral analyses of coal showed that vitrinite was the dominant maceral (up to 51.8 vol.%), whereas inertinite, liptinite, reactive semifusinite and visible minerals occurred in proportions of 22.6 vol.%, 2.9 vol.%, 5.3 vol.% and 17.5 vol.%, respectively. Theoretical calculations were developed and used to predict the resultant SO 2 emissions from the combustion of the Waterberg coal in a typical power plant. The sulphur content requirements to comply with the minimum emissions standards of 3500 mg/Nm 3 and 500 mg/Nm 3 were found to be ≤1.37 wt.% and ≤0.20 wt.%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Activity and structure of calcined coal gangue

    Energy Technology Data Exchange (ETDEWEB)

    Gong Chenchen; Li Dongxu; Wang Xiaojun; Li Zongjin [Nanjing University of Technology, Nanjing (China). College of Materials Science and Engineering

    2007-12-15

    Coal gangue was activated by means of calcination in seven temperature ranges. Systematic research was made about activation mechanism and structural evolution. The glycerin-ethanol method, SEM, MIP and XRD were used to determine the variation of structure and activation of coal gangue during calcination. The experimental results show that because of heat treatment in the range of calcination temperatures, mineral composition and microstructure of coal gangue are changed. In addition, its activity is improved. The amount of lime absorbed by the sample calcined at 700{sup o}C is 2-4 times that by uncalcined coal gangue in the course of hydration. When NaOH is added to coal gangue-lime system, the hydration reaction rate of the system is increased and the microstructure of hydrating samples of coal gangue is improved.

  11. Geochemistry of shale and sedimentary pyrite as a proxy for gold fertility in the Selwyn basin area, Yukon

    Science.gov (United States)

    Sack, Patrick J.; Large, Ross R.; Gregory, Daniel D.

    2018-01-01

    Selwyn basin area strata contain sedimentary pyrite with Au above background levels when analyzed by laser ablation-inductively coupled mass spectrometry. Hyland Group rocks contain framboidal pyrite contents of 670 ppb Au, 1223 ppm As, and 5.3 ppm Te; the mean of all types of sedimentary pyrite in the Hyland Group is 391 ppb Au, 1489 ppm As, and 3.8 ppm Te. These levels are similar to sedimentary pyrite in host lithologies from major orogenic gold districts in New Zealand and Australia. Comparison of whole rock and pyrite data show that rocks deposited in continental slope settings with significant terrigenous input contain pyrite that is consistently enriched in Au, As, Te, Co, and Cu. Although data are limited, whole rock samples of stratigraphic units containing Au-rich pyrite also contain high Au, indicating that most of the Au is within sedimentary pyrite. Based on geologic characteristics and comparison of pyrite chemistry data with whole rock chemistry, Selwyn basin area strata have the necessary ingredients to form orogenic gold deposits: Au-enriched source rocks, metamorphic conditions permissive of forming a metamorphic ore fluid, and abundant structural preparation for channeling fluids and depositing ore.

  12. Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS.

    Science.gov (United States)

    Lin, Zhiyong; Sun, Xiaoming; Peckmann, Jörn; Lu, Yang; Strauss, Harald; Xu, Li; Lu, Hongfeng; Teichert, Barbara M A

    2017-08-31

    Different sulfur isotope compositions of authigenic pyrite typically result from the sulfate-driven anaerobic oxidation of methane (SO4-AOM) and organiclastic sulfate reduction (OSR) in marine sediments. However, unravelling the complex pyritization sequence is a challenge because of the coexistence of different sequentially formed pyrite phases. This manuscript describes a sample preparation procedure that enables the use of secondary ion mass spectroscopy (SIMS) to obtain in situ δ 34 S values of various pyrite generations. This allows researchers to constrain how SO4-AOM affects pyritization in methane-bearing sediments. SIMS analysis revealed an extreme range in δ 34 S values, spanning from -41.6 to +114.8‰, which is much wider than the range of δ 34 S values obtained by the traditional bulk sulfur isotope analysis of the same samples. Pyrite in the shallow sediment mainly consists of 34 S-depleted framboids, suggesting early diagenetic formation by OSR. Deeper in the sediment, more pyrite occurs as overgrowths and euhedral crystals, which display much higher SIMS δ 34 S values than the framboids. Such 34 S-enriched pyrite is related to enhanced SO4-AOM at the sulfate-methane transition zone, postdating OSR. High-resolution in situ SIMS sulfur isotope analyses allow for the reconstruction of the pyritization processes, which cannot be resolved by bulk sulfur isotope analysis.

  13. Sulfur amino acids and alanine on pyrite (100) by X-ray photoemission spectroscopy: Surface or molecular role?

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Arenillas, M.; Galvez-Martinez, S.; Mateo-Marti, E., E-mail: mateome@cab.inta-csic.es

    2017-08-31

    Highlights: • Surface annealing pretreatment on pyrite surfaces can select molecular adsorption. • Enriched monosulfide species on pyrite (100) surface favors NH{sub 2} adsorption form. • Enriching disulfide species on pyrite (100) surface promotes NH{sub 3}{sup +} adsorption form. • Unique structure of each aminoacid provides a particular fingerprint in the process. • Spectroscopy evidence, pretreatment surface processes drives molecular adsorption. - Abstract: This paper describes the first successful adsorption of the cysteine, cystine, methionine and alanine amino acids on the pyrite (100) surface under ultra-high vacuum conditions with crucial chemical adsorption parameters driving the process. We have demonstrated by X-ray photoemission spectroscopy (XPS) that the surface pretreatment annealing process on pyrite surfaces is a critical parameter driving surface reactivity. The presence of enriched monosulfide species on the pyrite (100) surface favours the amino acid NH{sub 2} chemical form, whereas a longer annealing surface pretreatment of over 3 h repairs the sulfur vacancies in the pyrite, enriching disulfide species on the pyrite surface, which promotes NH{sub 3}{sup +} adsorption due to the sulfur vacancies in the pyrite being replaced by sulfur atom dimers (S{sub 2}{sup 2−}) on the surface. Furthermore, even if the surface chemistry (monosulfide or disulfide species enrichment) is the main factor promoting a partial conversion from NH{sub 2} to NH{sub 3}{sup +} species, the unique chemical structure of each amino acid provides a particular fingerprint in the process.

  14. The desulfurization mechanism of iron-manganese compound oxide desulfurizer for removal of COS from coal gas

    Energy Technology Data Exchange (ETDEWEB)

    Wang Fang-fang; Zhao Hai; Zhang De-xiang; Gao Jin-sheng [East China University of Science and Technology. Shanghai (China). School of Resource and Environmental Engineering

    2008-02-15

    The sorbent, atmospheric and components of outlet gas were analyzed by mass spectra, XRD, SEM, EDS etc. Desulfurisation performance of sorbents is good at 240 - 400 {sup o}C, atmospheric pressure and space speed of 500 - 2,000 h {sup -1}. The possible mechanism of desulfurisation reactions was obtained by analyzing the reduction- adsorption-sulfidation process. Carbon oxysulfide (COS) was converted to H{sub 2}S by hydrogen in strongly reducing atmosphere firstly. Then H{sub 2}S was adsorbed on the surface of desulfurizers, reacted with active component and transformed metal sulfides and water. Efficiency of removal of carbonyl sulfur is better in an atmosphere without carbonaceous oxide than in one with it, under test conditions. The existence of carbonaceous oxide restrains hydrogenation and the hydrolytic process of COS, which leads to a higher concentration of COS in the outlet. It is shown that chemical conversion is the main pathway in the reaction system of COS. Hydrogenation is the main process in the removal of COS from syngas. COS is preferentially catalyzed with active components n desulfurization sorbents, and generates H{sub 2}S which is subsequently absorbed. 13 refs., 4 figs., 2 tabs.

  15. A sustainable process to utilize ferrous sulfate waste from titanium oxide industry by reductive decomposition reaction with pyrite

    International Nuclear Information System (INIS)

    Huang, Penghui; Deng, Shaogang; Zhang, Zhiye; Wang, Xinlong; Chen, Xiaodong; Yang, Xiushan; Yang, Lin

    2015-01-01

    Highlights: • A newly developed treating process of ferrous sulfate was proposed. • The reaction process was discussed by thermodynamic analysis. • Thermodynamic analysis was compared with experiments results. • The kinetic model of the decomposition reaction was determined. • The reaction mechanism of autocatalytic reactions was explored. - Abstract: Ferrous sulfate waste has become a bottleneck in the sustainable development of the titanium dioxide industry in China. In this study, we propose a new method for the reductive decomposition of ferrous sulfate waste using pyrite. Thermodynamics analysis, tubular reactor experiments, and kinetics analysis were performed to analyze the reaction process. The results of the thermodynamic simulation showed that the reaction process and products were different when molar ratio of FeSO_4/FeS_2 was changed. The suitable molar ratio of FeSO_4/FeS_2 was 8–12. The reaction temperature of ferrous sulfate with pyrite was 580–770 K and the main products were Fe_3O_4 and SO_2. The simulation results agreed well with the experimental results. The desulphurization rate reached 98.55% and main solid products were Fe_3O_4 at 823.15 K when mole ratio of FeSO_4/FeS_2 was 8. Nano-sized magnetite was obtained at this condition. The kinetic model was investigated by isoconversional methods. The average E value was 244.34 kJ mol"−"1. The ferrous sulfate decomposition process can be treated as autocatalytic reaction mechanism, which corresponded to the expanded Prout–Tompson (Bna) model. The reaction mechanism of autocatalytic reactions during the process of ferrous sulfate decomposition were explored, the products of Fe oxide substances are the catalyst components.

  16. Trace element mapping of pyrite from Archean gold deposits – A comparison between PIXE and EPMA

    Energy Technology Data Exchange (ETDEWEB)

    Agangi, A., E-mail: aagangi@uj.ac.za [University of Johannesburg, Department of Geology, Auckland Park 2006 (South Africa); Przybyłowicz, W., E-mail: przybylowicz@tlabs.ac.za [Materials Research Department, iThemba LABS, National Research Foundation, Somerset West 7129 (South Africa); AGH University of Science and Technology, Faculty of Physics & Applied Computer Science, Al. A. Mickiewicza 30, 30-059 Krakow (Poland); Hofmann, A., E-mail: ahofmann@uj.ac.za [University of Johannesburg, Department of Geology, Auckland Park 2006 (South Africa)

    2015-04-01

    Chemical zoning of pyrites can record the evolution of mineralising fluids at widely varying P–T conditions ranging from diagenesis to medium-grade metamorphism. If preserved, zoning can reveal growth textures, brecciation and veining, resorption and recrystallisation events, thus shedding light on the processes that contributed to ore formation. Chemical zoning of sulfides is invisible in optical microscopy, but can be studied by chemical etching, high-contrast back-scattering electron images, and elemental imaging. In this study we compared micro-PIXE and WDS-EPMA elemental maps on the chemically zoned pyrites in mineralised vein-bearing samples from the Sheba and Fairview gold mines in the Barberton Greenstone Belt, South Africa. Elemental images show complex distribution of trace elements, suggesting multiple events of pyrite crystallisation and gold deposition. EPMA maps show fine-scale variations reflecting growth and recrystallisation textures marked, in particular, by variations of As, Ni, and Co. In PIXE maps, gold occurs both as finely-distributed and discrete inclusions, suggesting incorporation in the pyrite structure as solid solution, and deposition as electrum inclusions, respectively. Micro-PIXE and EPMA provide complementary information, forming together a powerful tool to obtain information on chemical zoning of pyrites in ore deposits.

  17. Ultravitrinite coals from Chukotka

    Energy Technology Data Exchange (ETDEWEB)

    Lapo, A.V.; Letushova, I.A.

    1979-03-01

    Chemical and petrographic analysis was conducted on coals from the Anadyrya and Bukhti Ugol'noi deposits. Characteristics of the most prevalent type of vitrinite coals in both regions are presented here. Anadyrya coals belong to a transitional phase between brown coal and long flame. Ultravitrinite coals predominate. Gas coals from Bukti Ugol'noi have a higher carbon content than Anadyrya coals. They also have a higher hydrogen content and yield of initial resin. In several cases there was also a higher yield of volatile substances. Chukotka coals are characterized by a 10 percent higher initial resin yield than equally coalified Donetsk coals, other indicators were equal to those of Donetsk coals. Because of this, Chukotka coals are suitable for fuel in power plants and as raw materials in the chemical industry. (15 refs.) (In Russian)

  18. Evaluation of the ignition behaviour of coals and blends

    Energy Technology Data Exchange (ETDEWEB)

    J. Faundez; F. Rubiera; X. Garcia; A. Arenillas; A.L. Gordon; J.J. Pis [CSIC, Instituto Nacional del Carbon, Oviedo (Spain). Department of Energy and Environment

    2003-07-01

    An experimental study about ignition of coals and blends was carried out by using an entrained flow reactor (EFR) with continuous feed. Seven coals of varying rank, from subbituminous to semianthracite, were tested and evolving gases (O{sub 2}, CO, CO{sub 2}, NO) were measured. The ignition temperature was evaluated from the evolution profiles of these gases, and correlated inversely to the reactivity of coals, as reflected by increasing values of ignition temperatures in the sequence subbituminous, high volatile bituminous, low volatile bituminous and semianthracite coals. Mechanism of ignition varied from an heterogeneous mechanism (for subbituminous, low volatile bituminous and semianthracite coals) to an homogeneous mechanism (for high volatile bituminous coal). Experiments with coal blends showed that if a low volatile bituminous coal is blended with a high volatile bituminous coal, the latter determines the value of the ignition temperature and ignition mechanism of the blend, when its percentage in the blend is 50% or higher. For blends of subbituminous and high volatile bituminous coals, the ignition mechanism of the blend is determined by the ignition mechanism of the coal with a higher content in the blend. 12 refs., 9 figs., 1 tab.

  19. Coal Tar and Coal-Tar Pitch

    Science.gov (United States)

    Learn about coal-tar products, which can raise your risk of skin cancer, lung cancer, and other types of cancer. Examples of coal-tar products include creosote, coal-tar pitch, and certain preparations used to treat skin conditions such as eczema, psoriasis, and dandruff.

  20. Content of arsenic, selenium, mercury in the coal, food, clay and drinking water on the Zhaotong fluorosis area, eastern Yunnan Province

    Energy Technology Data Exchange (ETDEWEB)

    Luo Kun-li; Li Hui-jie; Chen Tong-bin (and others) [Chinese Academy of Sciences, Beijing (China). Institute of Geographic Sciences and Natural Resources Research

    2008-03-15

    About 160 samples of coal, corn, capsicum and drinking water were collected from the endemic fluorosis area of Zhenxiong and Weixin County, Zhaotong City of Yunnan Province, to determine the arsenic (As), selenium (Se) and mercury (Hg) content by AAF-800. The study found that the As content in the main coal seam from the Late Permian coal mines in Zhaotong City is 8.84 mg/kg and some civil coal can reach 89.09 mg/kg. The Se and Hg in the coal samples of Late Permian is lower, but Se and Hg are more concentrated in the pyritic coal balls and the pyritic gangue of the coal seam. The As content in corn and capsicum dried by coal-burning is more than 0.7 mg/kg, the natural standard amount of arsenic content permitted in food by China. The Se and Hg content in corn dried by coal-burning is lower than the natural standard of Se and Hg content in food in China but the Se and Hg content of capsicum dried by coal-burning exceeds the amount permitted by the natural standard for food in China. Clay, used as an additive for the coal-burning process and as a binder in making briquettes, contains a high content of As, generally more than 16 mg/kg. However, the Se and Hg content of clay itself are low. The As, Se and Hg content of drinking water are lower than the natural standard of As, Se and Hg content in the drinking water. So, there is high-As content coal and high-As content dried corn and capsicum in the endemic fluorosis area of Zhaotong City of Yunnan Province. The high As content of the dried corn and capsicum might have originated from the high arsenic content of burnt coal and clay. 30 refs., 4 tabs.

  1. Tribocharging in electrostatic beneficiation of coal: Effects of surface composition on work function as measured by x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy in air

    International Nuclear Information System (INIS)

    Trigwell, S.; Mazumder, M.K.; Pellissier, R.

    2001-01-01

    The cleaning of coal by electrostatic beneficiation is based on tribocharging characteristics of pulverized coal particles with diameter smaller than 120 μm. The tribocharging process should be such that the organic coal particles must charge with a polarity opposite to that of the sulfur and the mineral containing particles so that coal can be separated from minerals by using a charge separator. However, the charge distribution of electrostatically separated coal particles indicates that coal exhibits bipolar charging. A significant fraction of the coal particles charges negatively which appears to be in conflict with expectations in that the organic coal particles should charge positively, and the mineral particles, present as impurities such as pyrite, charge negatively when tribocharged against copper. The relative work functions of the particles (coal and mineral) and that of the metal surface (copper or stainless steel) used for tribocharging predict these expected results. However, ultraviolet photoelectron spectroscopy (UPS) measurements in air on specimens of three different coal species, showed the work function to be approximately 5.4 eV, which is higher than a reported measured work function of 3.93 eV. Studies by UPS and x-ray photoelectron spectroscopy on copper, stainless steel, aluminum, and other commonly used tribocharging materials such as nylon and polytetrafluorethylene, as well as pure pyrite, showed that the work function varied considerably as a function of surface composition. Therefore, the reason for the bipolar charging of the coal particles may be the too small differences in work functions between coal powder and copper used as the charging material. The choice of a material for impaction triboelectric charging for coal or mineral separation should therefore depend upon the actual work function as modified by the ambient conditions such as moisture content and the oxidation of the surface

  2. Geochemistry of Toxic Elements and Their Removal via the Preparation of High-Uranium Coal in Southwestern China

    Directory of Open Access Journals (Sweden)

    Piaopiao Duan

    2018-02-01

    Full Text Available High-uranium (U coal is the dominant form of coal in Southwestern China. However, directly utilizing this resource can also harm the environment because this element is radioactive; it is, therefore, necessary to clean this kind of coal before burning. This research studied the geochemistry of toxic elements and their partitioning during the preparation of high-U coal in China. The results show that high-U coals are mainly distributed in Southwestern China and are characterized by a high organic sulfur (S content and vanadium (V-chromium (Cr-molybdenum (Mo-U element assemblage. These elements are well-correlated with one another, but are all negatively related to ash yield, indicating that all four are syngenetic in origin and associated with organic materials. A mineralogical analysis shows that U in Ganhe and Rongyang coal occurs within fine-grained anatase, clay minerals, guadarramite, and pyrite, while V occurs in clay minerals, pyrite, and dolomite, and Cr occurs in dolomite. Other elements, such as fluorine (F, lead (Pb, selenium (Se, and mercury (Hg, mainly occur in pyrite. By applying a gravity separation method to separate minerals from coal, the content of the enrichment element assemblage of V-Cr-Mo-U in Rongyang coal is still shown to be higher than, or close to, that of the original feed because this element assemblage is derived from hydrothermal fluids during syngenetic or early diagenetic phases, but other elements (beryllium [Be], F, manganese [Mn], zinc [Zn], Pb, arsenic [As], Se, Hg can be efficiently removed. Once cleaned, the coal obtained by gravity separation was subject to a flotation test to separate minerals; these results indicate that while a portion of V and Cr can be removed, Mo and U remain difficult to extract. It is evident that the two most commonly utilized industrialized coal preparation methods, gravity separation and flotation, cannot effectively remove U from coal where this element occurs in large

  3. Galvanic Interaction between Chalcopyrite and Pyrite with Low Alloy and High Carbon Chromium Steel Ball

    Directory of Open Access Journals (Sweden)

    Asghar Azizi

    2013-01-01

    Full Text Available This study was aimed to investigate the galvanic interaction between pyrite and chalcopyrite with two types of grinding media (low alloy and high carbon chromium steel ball in grinding of a porphyry copper sulphide ore. Results indicated that injection of different gases into mill altered the oxidation-reduction environment during grinding. High carbon chromium steel ball under nitrogen gas has the lowest galvanic current, and low alloy steel ball under oxygen gas had the highest galvanic current. Also, results showed that the media is anodic relative to pyrite and chalcopyrite, and therefore pyrite or chalcopyrite with a higher rest potential acted as the cathode, whilst the grinding media with a lower rest potential acted as the anode, when they are electrochemically contacted. It was also found that low alloy steel under oxygen produced the highest amount of EDTA extractable iron in the slurry, whilst high carbon chromium steel under nitrogen atmosphere led to the lowest amount.

  4. Microbial Oxidation of Pyrite Coupled to Nitrate Reduction in Anoxic Groundwater Sediment

    DEFF Research Database (Denmark)

    Jørgensen, Christian Juncher; Elberling, Bo; Jacobsen, Ole Stig

    2009-01-01

    denitrification process with pyrite as the primary electron donor. The process demonstrates a temperature dependency (Q10) of 1.8 and could be completely inhibited by addition of a bactericide (NaN3). Experimentally determined denitrification rates show that more than 50% of the observed nitrate reduction can...... be ascribed to pyrite oxidation. The apparent zero-order denitrification rate in anoxic pyrite containing sediment at groundwater temperature has been determined to be 2-3 µmol NO3- kg-1 day-1. The in situ groundwater chemistry at the boundary between the redoxcline and the anoxic zone reveals that between 65......-anoxic boundary in sandy aquifers thus determining the position and downward progression of the redox boundary between nitrate-containing and nitrate-free groundwater....

  5. Phytoremediation of spoil coal dumps in Western Donbass (Ukraine)

    Science.gov (United States)

    Klimkina, Iryna; Kharytonov, Mykola; Wiche, Oliver; Heilmeier, Hermann

    2017-04-01

    At the moment, in Ukraine about 150 thousand hectares of fertile land are occupied by spoil dumps. Moreover, this figure increases every year. According to the technology used about 1500 m3 of adjacent stratum is dumped at the surface per every 1000 tons of coal mined. Apart from land amortization, waste dumps drastically change the natural landscape and pollute air, soil and water sources as the result of water and wind erosion, as well as self-ignition processes. A serious concern exists with respect to the Western Donbass coal mining region in Ukraine, where the coal extraction is made by the subsurface way and solid wastes are represented by both spoil dumps and wastes after coal processing. Sulphides, mostly pyrite (up to 4% of waste material), are widely distributed in the waste heaps freshly removed due to coal mining in Western Donbass.The oxidation of pyrite with the presence of oxygen and water is accompanied by a sharp drop in the pH from the surface layer to the spoil dumps(from 5.2-6.2 to 3.9-4.2 in soil substrates with chernozen and from 8.3-8.4 to 6.7-7.2 in soil substrates with red-brown clay, stabilizing in dump material in both cases at 2.9-3.2). Low pH generates the transformation of a number of toxic metals and other elementspresent in waste rock (e.g. Fe, Al, Mn, Zn, Mo, Co, As, Cd, Bi, Pb, U) into mobile forms. To stabilize and reduce metal mobility the most resistant plants that occur naturally in specified ecosystems can be used. On coal spoil dumpsin Western Donbas the dominant species are Bromopsis inermis, subdominant Artemisia austriaca; widespread are also Festucas pp., Lathyrus tuberosus, Inula sp., Calamagrostis epigeios, Lotus ucrainicus, and Vicias pp. Identification of plants tolerant to target metals is a key issue in phytotechnology for soil restoration. It is hypothesized that naturally occurring plants growing on coal spoil dumps can be candidates for phytostabilization, phytoextraction (phytoaccumulation) and phytomining

  6. Environmental assessment and nano-mineralogical characterization of coal, overburden and sediment from Indian coal mining acid drainage

    Directory of Open Access Journals (Sweden)

    Madhulika Dutta

    2017-11-01

    the presence both of pyrite and marcasite which was also confirmed in XRD and Mossbauer spectral analysis. The presented data of the minerals and ultra/nano-particles present shows their ability to control the mobility of hazardous elements, suggesting possible use in environmental management technology, including restoration of the delicate Indian coal mine areas.

  7. Isotopic and elemental chemistry of sedimentary pyrite: A combined analytical and statistical approach to a novel planetary biosignature

    Science.gov (United States)

    Figueroa, M. C.; Gregory, D. D.; Lyons, T. W.; Williford, K. H.

    2017-12-01

    Life processes affect trace element abundances in pyrite such that sedimentary and hydrothermal pyrite have significantly different trace element signatures. Thus, we propose that these biogeochemical data could be used to identify pyrite that formed biogenetically either early in our planet's history or on other planets, particularly Mars. The potential for this approach is elevated because pyrite is common in diverse sedimentary settings, and its trace element content can be preserved despite secondary overprints up to greenschist facies, thus minimizing the concerns about remobilization that can plague traditional whole rock studies. We are also including in-situ sulfur isotope analysis to further refine our understanding of the complex signatures of ancient pyrite. Sulfur isotope data can point straightforwardly to the involvement of life, because pyrite in sediments is inextricably linked to bacterial sulfate reduction and its diagnostic isotopic expressions. In addition to analyzing pyrite of known biological origin formed in the modern and ancient oceans under a range of conditions, we are building a data set for pyrite formed by hydrothermal and metamorphic processes to minimize the risk of false positives in life detection. We have used Random Forests (RF), a machine learning statistical technique with proven efficiency for classifying large geological datasets, to classify pyrite into biotic and abiotic end members. Coupling the trace element and sulfur isotope data from our analyses with a large existing dataset from diverse settings has yielded 4500 analyses with 18 different variables. Our initial results reveal the promise of the RF approach, correctly identifying biogenic pyrite 97 percent of the time. We will continue to couple new in-situ S-isotope and trace element analyses of biogenic pyrite grains from modern and ancient environments, using cutting-edge microanalytical techniques, with new data from high temperature settings. Our ultimately goal

  8. Late Cretaceous coal overlying karstic bauxite deposits in the Parnassus-Ghiona Unit, Central Greece: Coal characteristics and depositional environment

    Energy Technology Data Exchange (ETDEWEB)

    Kalaitzidis, Stavros; Siavalas, George; Christanis, Kimon [Dept. of Geology, University of Patras, 26504 Rio-Patras (Greece); Skarpelis, Nikos [Dept. of Geology and Geoenvironment, University of Athens, 15784 Zografou (Greece); Araujo, Carla Viviane [Petrobras-Cenpes GEOQ/PDEXP, Rua Horacio Macedo n 950, Cidade Universitaria - Ilha do Fundao, 21941-915 Rio de Janeiro (Brazil)

    2010-04-01

    The Pera-Lakkos coal located on top of bauxite deposits in the Ghiona mining district (Central Greece), is the only known Mesozoic (Late Cretaceous) coal in the country. It was derived from herbaceous plants and algae growing in mildly brackish mires that formed behind a barrier system during a regression of the sea, on a karstified limestone partly filled in with bauxitic detritus. Petrological, mineralogical and geochemical data point to the predominance of reducing conditions and intense organic matter degradation in the palaeomires. O/C vs. H/C and OI vs. HI plots, based on elemental analysis and Rock-Eval data, characterize kerogen types I/II. This reflects the relatively high liptinite content of the coal. Besides kerogen composition, O/C vs. H/C plot for the Pera-Lakkos coals is in accordance with a catagenesis stage of maturation in contrast with vitrinite reflectance and T{sub max} from Rock-Eval pyrolysis, which indicate the onset of oil window maturation stage. Suppression of vitrinite reflectance should be considered and the high liptinite content corroborates this hypothesis. Despite some favourable aspects for petroleum generation presented by the Pera-Lakkos coal, its maximum thickness (up to 50 cm) points to a restricted potential for petroleum generation. Coal oxidation took place either during the late stage of peat formation, due to wave action accompanying the subsequent marine transgression, or epigenetically after the emergence of the whole sequence due to percolation of drainage waters. Both options are also supported by the REE shale-normalized profiles, which demonstrate an upwards depletion in the coal layer. Oxidation also affected pyrite included in the coal; this led to the formation of acidic (sulfate-rich) solutions, which percolated downwards resulting in bleaching of the upper part of the underlying bauxite. (author)

  9. Pyrite-enhanced methylene blue degradation in non-thermal plasma water treatment reactor

    Energy Technology Data Exchange (ETDEWEB)

    Benetoli, Luis Otavio de Brito, E-mail: luskywalcker@yahoo.com.br [Departamento de Quimica, Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil); Cadorin, Bruno Mena; Baldissarelli, Vanessa Zanon [Departamento de Quimica, Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil); Geremias, Reginaldo [Departamento de Ciencias Rurais, Universidade Federal de Santa Catarina (UFSC), Curitibanos, SC (Brazil); Goncalvez de Souza, Ivan [Departamento de Quimica, Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil); Debacher, Nito Angelo, E-mail: debacher@qmc.ufsc.br [Departamento de Quimica, Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2012-10-30

    Highlights: Black-Right-Pointing-Pointer We use O{sub 2} as the feed gas and pyrite was added to the non-thermal plasma reactor. Black-Right-Pointing-Pointer The methylene blue removal by NTP increased in the presence of pyrite. Black-Right-Pointing-Pointer The total organic carbon content decreased substantially. Black-Right-Pointing-Pointer The acute toxicity test showed that the treated solution is not toxic. Black-Right-Pointing-Pointer The dye degradation occurs via electron impact as well as successive hydroxylation. - Abstract: In this study, methylene blue (MB) removal from an aqueous phase by electrical discharge non-thermal plasma (NTP) over water was investigated using three different feed gases: N{sub 2}, Ar, and O{sub 2}. The results showed that the dye removal rate was not strongly dependent on the feed gas when the electrical current was kept the same for all gases. The hydrogen peroxide generation in the water varied according to the feed gas (N{sub 2} < Ar < O{sub 2}). Using O{sub 2} as the feed gas, pyrite was added to the reactor in acid medium resulting in an accentuated increase in the dye removal, which suggests that pyrite acts as a Fenton-like catalyst. The total organic carbon (TOC) content of the dye solution decreased slightly as the plasma treatment time increased, but in the presence of the pyrite catalyst the TOC removal increased substantially. The acute toxicity test using Artemia sp. microcrustaceans showed that the treated solution is not toxic when Ar, O{sub 2} or O{sub 2}-pyrite is employed. Electrospray ionization mass spectrometry analysis (ESI-MS) of the treated samples indicated that the dye degradation occurs via high energy electron impact as well as successive hydroxylation in the benzene rings of the dye molecules.

  10. Record coking coal settlements

    Energy Technology Data Exchange (ETDEWEB)

    Macdonald, C.

    2005-02-01

    The US$100/tonne psychological barrier in coking coal prices has been well and truly smashed. The article examines developments in coal pricing. It includes quotes from many senior executives in the coal industry as collected at McCloskey's Australian Coal.04 conference held in Sydney, 18-19 November 2004. 2 photos.

  11. COAL Conference Poster

    OpenAIRE

    Brown, Taylor Alexander; McGibbney, Lewis John

    2017-01-01

    COAL Conference Poster This archive contains the COAL conference poster for the AGU Fall Meeting 2017 by Taylor Alexander Brown. The Inkscape SVG source is available at https://github.com/capstone-coal/coal-conference-poster/ under the Creative Commons Attribution-ShareAlike 4.0 International license.

  12. Trace element geochemistry and mineralogy of coal from Samaleswari open cast coal block (S-OCB), Eastern India

    Science.gov (United States)

    Saha, Debasree; Chatterjee, Debashis; Chakravarty, Sanchita; Mazumder, Madhurina

    2018-04-01

    Coal samples of Samaleswari open cast coal block (S-OCB) are high ash (Aad, mean value 35.43%) and low sulphur content (St, on dry basis, mean value 0.91% analysis. The work is further supported by the use of chemical fractionation experiment that reveals the multi mode of occurrence of several environmentally concern and interested trace elements (Sb, As, Be, Cd, Cr, Co, Cu, Pb, Mn, Ni, Zn). Among the analysed trace elements Co, Mn and Zn have major silicate association along with significant carbonate/oxide/monosulfide association. Whereas As, Cd, Cu, Pb and Ni have dominant pyritic association with notable silicate and carbonate/oxide/monosulfide association. The rest three elements (Sb, Be, Cr) have principally organic association with minor silicate and carbonate/oxide/monosulfide association. The stratigraphic variation of organo-mineral matrix content and detrital-authigenic mineral ratio are primarily related to coal rank. Geochemical character of coal also reflects a light towards proper utilisation of S-OCB coal from technical and environmental view point.

  13. Arsenic, copper and zinc occurrence at the Wangaloa coal mine, southeast Otago, New Zealand

    International Nuclear Information System (INIS)

    Black, A.; Craw, D.

    2001-01-01

    Waste piles, created from open cast coal mining activities at the abandoned Wangaloa mine in SE Otago, have exposed pyrite (FeS 2 ) to atmospheric conditions. This has led to the acidification of the surface tailings and nearby drainage waters (acid mine drainage, AMD). Mobilisation of trace metals arsenic (As), copper (Cu), and zinc (Zn) has occurred, partly as a result of the low pH levels (ca. pH 2-4), leading to elevated concentrations of these metals in receiving waters. Authigenic pyrite deposited in a marginal marine coal-forming environment is enriched in As with levels reaching up to 100 ppm. Copper and Zn in solid solution are not elevated above background levels in either coal measures or associated pyrite. Water discharges, sediments, waste rock and background samples were sampled and analysed during the driest (summer) and wettest (winter) seasons of 1998 and 1999. During the winter season, water discharging from the waste piles contained up to 0.7 ppm (mg/kg) As, as measured in 1998. During the 1999 wettest season, no such levels of As were observed, with the highest level attaining 0.07 ppm As. Copper and Zn were locally elevated in waters, with Zn concentrations reaching 1 ppm. During the summer season of 1999, only one sampling site recorded elevated metal concentrations. Adverse effects from the remnant waste piles appear to be highly localised due to downstream natural remediation processes occurring in a wetland area. The absence of strongly elevated metal concentrations during the drier season is a result of strongly depressed water levels within the waste piles. Flushing of acid and metals occurs when the water levels increase with the onset of the winter season. During the summer season, pyrite within the waste piles has been readily decomposing from the increased availability and transport of atmospheric oxygen

  14. Bioleaching of low grade uranium ore containing pyrite using A. ferrooxidans and A. thiooxidans

    International Nuclear Information System (INIS)

    Alexey Borisovich Umanskii; Anton Mihaylovich Klyushnikov

    2013-01-01

    A process of uranium extraction from ore containing 3.1 % pyrite by bacterial leaching was investigated in shaken flasks during 90 days. The highest uranium recovery amounting to 85.1 % was obtained using binary mixture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans that was exceeding results obtained by traditional acid leaching technique up to 27 %. High uranium recovery was founded to be due to the high degree of pyrite dissolution that can be readily achieved by bacterial leaching (up to 98.0 %). (author)

  15. DFT study on the galvanic interaction between pyrite (100) and galena (100) surfaces

    International Nuclear Information System (INIS)

    Ke, Baolin; Li, Yuqiong; Chen, Jianhua; Zhao, Cuihua; Chen, Ye

    2016-01-01

    Graphical abstract: - Highlights: • Galvanic interaction is weakened with the increase of contact distance. • Electronic transfer mainly occurs on the contact layers. • Galvanic effect enhances nucleophilicity of galena and electrophilicity of pyrite. • Presence of H_2O increases the galvanic interaction. - Abstract: The galvanic interaction between pyrite and galena surface has been investigated using density functional theory (DFT) method. The calculated results show that galvanic interactions between pyrite and galena surface are decreased with the increase of contact distance. The galvanic interactions still occurs even the distance larger than the sum of two atoms radius (≈2.8 Å), and the limit distance of galvanic interaction between galena and pyrite surface is about 10 Å, which is consistent with the quantum tunneling effect. Through Mulliken charge population calculation, it is found that electrons transfer from galena to pyrite. For galena surface, Pb 6s and 6p states lose electrons and S 3p state loses a small amount of electrons, which causes the electron loss of galena. For pyrite surface, Fe 4p state obtains large numbers of electrons, resulting in the decrease of positive charge of Fe atom. However, the 3p state of S atom loses a small numbers of electrons. The reactivity of mineral surface has also been studied by calculating the frontier orbitals of minerals. Results suggest that the highest occupied molecular orbital (HOMO) coefficients of galena are increased whereas those of pyrite are decreased with the enhancing galvanic interaction, indicating that the oxidation of galena surface would be enhanced due to the galvanic interaction. The Fukui indices and dual descriptor values of surface atoms suggest that the nucleophilicity of the galena surface increases, meanwhile, the electrophilicity of pyrite surface increases with the decrease of the contact distance. In addition, the density of states (DOS) of atoms results show that the

  16. Coal option. [Shell Co

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-01

    This paper notes the necessity of developing an international coal trade on a very large scale. The role of Shell in the coal industry is examined; the regions in which Shell companies are most active are Australia, Southern Africa, Indonesia; Europe and North America. Research is being carried out on marketing and transportation, especially via slurry pipelines; coal-oil emulsions; briquets; fluidized-bed combustion; recovery of coal from potential waste material; upgrading of low-rank coals; unconventional forms of mining; coal conversion (the Shell/Koppers high-pressure coal gasification process). Techniques for cleaning flue gas (the Shell Flue Gas Desulfurization process) are being examined.

  17. Concerning coal: an anthology

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, M.; Hawse, M.L.; Maloney, P.J. [eds.

    1997-12-31

    The anthology takes a humanistic look at coal mining in Illinois. One of its goals is to increase public awareness of coal in American society; it also seeks to enhance understanding of the historical aspects of coal and to study the impact of coal on mining families. Many of the 25 selections in the anthology come from Coal Research Center publications, `Concerning coal` and `Mineral matters`. Articles are arranged in three parts entitled: life in the mining community; mining in folklore, story telling, literature, art and music; and technology as it affected the people of the coal fields. 117 refs., 25 photos. 1 map.

  18. A review of acidity generation and consumption in acidic coal mine lakes and their watersheds.

    Science.gov (United States)

    Blodau, Christian

    2006-10-01

    Lakes developing in former coal mine pits are often characterized by high concentrations of sulfate and iron and low pH. The review focuses on the causes for and fate of acidity in these lakes and their watersheds. Acidification is primarily caused by the generation of ferrous iron bearing and mineralized groundwater, transport through the groundwater-surface water interface, and subsequent iron oxidation and precipitation. Rates of acidity generation in mine tailings and dumps, and surface water are often similar (1 to >10 mol m(-2) yr(-1)). Weathering processes, however, often suffice to buffer groundwaters to only moderately acidic or neutral pH, depending on the suite of minerals present. In mine lakes, the acidity balance is further influenced by proton release from transformation of metastable iron hydroxysulfate minerals to goethite, and proton and ferrous iron sequestration by burial of iron sulfides and carbonates in sediments. These processes mostly cannot compensate acidity loading from the watershed, though. A master variable for almost all processes is the pH: rates of pyrite oxidation, ferrous iron oxidation, mineral dissolution, iron precipitation, iron hydroxide transformation, and iron and sulfate reduction are strongly pH dependent. While the principle mechanism of acidity generation and consumption and several controls are mostly understood, this cannot be said about the fate of acidity on larger spatial and temporal scales. Little is also known about critical loads and the internal regulation of biogeochemical iron, sulfur, and carbon cycling in acidic mine lakes.

  19. A review of acidity generation and consumption in acidic coal mine lakes and their watersheds

    International Nuclear Information System (INIS)

    Blodau, Christian

    2006-01-01

    Lakes developing in former coal mine pits are often characterized by high concentrations of sulfate and iron and low pH. The review focuses on the causes for and fate of acidity in these lakes and their watersheds. Acidification is primarily caused by the generation of ferrous iron bearing and mineralized groundwater, transport through the groundwater-surface water interface, and subsequent iron oxidation and precipitation. Rates of acidity generation in mine tailings and dumps, and surface water are often similar (1 to >10 mol m -2 yr -1 ). Weathering processes, however, often suffice to buffer groundwaters to only moderately acidic or neutral pH, depending on the suite of minerals present. In mine lakes, the acidity balance is further influenced by proton release from transformation of metastable iron hydroxysulfate minerals to goethite, and proton and ferrous iron sequestration by burial of iron sulfides and carbonates in sediments. These processes mostly cannot compensate acidity loading from the watershed, though. A master variable for almost all processes is the pH: rates of pyrite oxidation, ferrous iron oxidation, mineral dissolution, iron precipitation, iron hydroxide transformation, and iron and sulfate reduction are strongly pH dependent. While the principle mechanism of acidity generation and consumption and several controls are mostly understood, this cannot be said about the fate of acidity on larger spatial and temporal scales. Little is also known about critical loads and the internal regulation of biogeochemical iron, sulfur, and carbon cycling in acidic mine lakes. (author)

  20. Coal information 1995

    International Nuclear Information System (INIS)

    1996-01-01

    This volume is a comprehensive reference book on current world coal market trends and long-term prospects to 2010. It contains an in-depth analysis of the 1995 international coal market covering prices, demand, trade, supply and production capacity as well as over 450 pages of country specific statistics on OECD and key non-OECD coal producing and consuming countries. The book also includes a summary of environmental policies on climate change and on coal-related air quality issues as well as essential facts on coal-fired power stations in coal-importing regions, on coal ports world-wide and on emission standards for coal-fired boilers in OECD countries. Coal Information is one of a series of annual IEA statistical publications on major energy sources; other reports are Oil and Gas Information and Electricity Information. Coal Information 1995 is published in July 1996. (author)

  1. Coal yearbook 1993

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    This book is the first coal yearbook published by ATIC (France). In a first chapter, economical context of coal worldwide market is analyzed: comparative evaluations on coal exports and imports, coal industry, prices, production in USA, Australia, South Africa, China, former USSR, Poland, Colombia, Venezuela and Indonesia are given. The second chapter describes the french energy context: national coal production, imports, sectorial analysis, maritime transport. The third chapter describes briefly the technologies of clean coal and energy saving developed by Charbonnages de France: fossil-fuel power plants with combined cycles and cogeneration, fluidized beds for the recovery of coal residues, recycling of agricultural wastes (sugar cane wastes) in thermal power plant, coal desulfurization for air pollution abatement. In the last chapter, statistical data on coal, natural gas and crude oil are offered: world production, world imports, world exports, french imports, deliveries to France, coal balance, french consumption of primary energy, power generation by fuel type

  2. Coal plows in underground mines in Czechoslovakia

    Energy Technology Data Exchange (ETDEWEB)

    Vasek, J.; Klimek, M.

    1980-05-01

    This article discusses factors which influence the possibility of using coal plows for mining black coal seams in Czechoslovakia. Seams inclined at angles up to 40 degrees can be mined by plows. Another factor which influences plow work is ease of separating coal seam from the direct roof: the plow can be used in seams with good or average separation, and can not be used in seams with roofs difficult to separate from the seam. Quality of rocks surrounding the coal seam: If the stability of the roof is low and strength of rock is low and roof falls occur easily coal plows can not be used. From among three classes of rock in Czechoslovakia plows can be used only in the class characterized by the highest strength. Intense seam dislocations are one of the most important difficulties in using coal plows. Plows can be used if height of seam dislocations is not greater than 40% of the seam thickness. Further factors which influence the possibility of using coal plows (coal resistance to cutting, features of cutting elements of the plow, specific features of the plow mechanism etc.) are also discussed. A method for assessing advantages and disadvantages of using coal plows in given circumstances is presented. (10 refs.) (In Czech)

  3. ACR coal 1992

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    This publication is a comprehensive reference document on production, exports, prices and demand of coal in world markets. A forecast of demand by coal type and country up to the year 2000 is provided. Statistics of the Australian export industry are complemented by those of South Africa, USA, Canada, Indonesia, China, C.I.S. and Colombia. A very comprehensive coal quality specification for nearly all the coal brands exported from Australia, as well as leading non-Australian coal brands, is included.

  4. Assessing coal burnout

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, A. [Pacific Power, Sydney, NSW (Australia)

    1999-11-01

    Recent research has allowed a quantitative description of the basic process of burnout for pulverized coals to be made. The Cooperative Research Centre for Black Coal Utilization has built on this work to develop a coal combustion model which will allow plant engineers and coal company representatives to assess their coals for combustion performance. The paper describes the model and its validation and outlines how it is run. 2 figs.

  5. Thallium-rich pyrite ores from the Apuan Alps, Tuscany, Italy:constraints for their origin and environmental concerns

    Science.gov (United States)

    D'Orazio, Massimo; Biagioni, Cristian; Dini, Andrea; Vezzoni, Simone

    2017-06-01

    The southern sector of the Apuan Alps (AA) massif, Tuscany, Italy, is characterized by the occurrence of a series of baryte-pyrite-iron oxide orebodies whose Tl-rich nature was recognized only recently. The geochemistry of the pyrite ore was investigated through inductively coupled plasma mass spectrometry. In addition, lead isotope data for selected pyrite ores from AA were collected. Pyrite ores are characterized by a complex geochemistry, with high concentrations of Tl (up to 1100 μg/g) coupled with high As and Sb contents; the Co/Ni ratio is always <1. Geochemical data of pyrite and marcasite ore samples from other mining districts of Tuscany have been collected in order to compare them with those from the AA. These samples usually have very low Tl content (less than 2 μg/g) and high to very high Co/Ni and As/Sb ratios. Only some samples from the Sb-Hg ore deposits showed very high Tl concentrations (up to 3900 μg/g). Another difference is related to the lead isotope composition, with pyrite ores from AA markedly less radiogenic than those from the other deposits from Tuscany. Geochemical data of pyrite ores from AA give new insights on the genesis of the baryte-pyrite-iron oxide orebodies, relating their formation to low-temperature hydrothermal systems active during early Paleozoic; in addition, these data play a fundamental role in assessing the environmental impact of these deposits.

  6. Element migration of pyrites during ductile deformation of the Yuleken porphyry Cu deposit (NW-China)

    Science.gov (United States)

    Hong, Tao; Xu, Xing-Wang; Gao, Jun; Peters, Stephen; Li, Jilei; Cao, Mingjian; Xiang, Peng; Wu, Chu; You, Jun

    2017-01-01

    The strongly deformed Yuleken porphyry Cu deposit (YPCD) occurs in the Kalaxiangar porphyry Cu belt (KPCB), which occupies the central area of the Central Asian Orogenic Belt (CAOB) between the Sawu’er island arc and the Altay Terrane in northern Xinjiang. The YPCD is one of several typical subduction-related deposits in the KPCB, which has undergone syn-collisional and post-collisional metallogenic overprinting. The YPCD is characterized by three pyrite-forming stages, namely a hydrothermal stage A (Py I), a syn-ductile deformation stage B (Py II) characterized by Cu-Au enrichment, and a fracture-filling stage C (Py III). In this study, we conducted systematic petrographic and geochemical studies of pyrites and coexist biotite, which formed during different stages, in order to constrain the physicochemical conditions of the ore formation. Euhedral, fragmented Py I has low Pb and high Te and Se concentration and Ni contents are low with Co/Ni ratios mostly between 1 and 10 (average 9.00). Py I is further characterized by enrichments of Bi, As, Ni, Cu, Te and Se in the core relative to the rim domains. Anhedral round Py II has moderate Co and Ni contents with high Co/Ni ratios >10 (average 95.2), and average contents of 46.5 ppm Pb and 5.80 ppm Te. Py II is further characterized by decreasing Bi, Cu, Pb, Zn, Ag, Te, Mo, Sb and Au contents from the rim to the core domains. Annealed Py III has the lowest Co content of all pyrite types with Co/Ni ratios mostly <0.1 (average 1.33). Furthermore, Py III has average contents of 3.31 ppm Pb, 1.33 ppm Te and 94.6 ppm Se. In addition, Fe does not correlate with Cu and S in the Py I and Py III, while Py II displays a negative correlation between Fe and Cu as well as a positive correlation between Fe and S. Therefore, pyrites which formed during different tectonic regimes also have different chemical compositions. Biotite geothermometer and oxygen fugacity estimates display increasing temperatures and oxygen

  7. Effect of properties of iron compounds on the catalytic activity in direct coal liquefaction; Tetsu kagobutsu no keitai to sekitan ekika kassei

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, T.; Tazawa, K. [Mitsubishi Chemical Corp., Tokyo (Japan); Shimasaki, K. [Kobe Steel Ltd. (Japan)

    1998-08-20

    When considering merchandising scale of the coal liquefaction process, it is a preliminary condition that metal used for its catalyst is rich in resource volume, cheap in production cost, without pollution, and so forth, and application of cheap iron ore and ferrous compounds to disposable catalyst is desired. As liquefaction activity of the iron ore was hitherto improved by its micro crushing, its mechanical crush had a limit of about 2 {mu}m in mean particle diameter. However, together with recent crushing technique, crushers with high performance were developed, and then micro crushing by sub-micron became possible industri8ally even for iron ore. In this study, three kinds of Australian iron ores such as limonite of ferric hydroxide type iron ore, pyrite of ferrous sulfide type, and hematite of ferric oxide type were micro crushed to examine coal liquefaction activity and hydrogenation reaction activity of 1-methyl naphthalene (1-MN) and also relationship between properties and activity of catalyst for the latter before and after reaction. 11 refs., 8 figs., 5 tabs.

  8. Effect of sewage sludge on formation of acidic ground water at a reclaimed coal mine

    Science.gov (United States)

    Cravotta, C.A.

    1998-01-01

    Data on rock, ground water, vadose water, and vadose gas chemistry were collected for two years after sewage sludge was applied at a reclaimed surface coal mine in Pennsylvania to determine if surface-applied sludge is an effective barrier to oxygen influx, contributes metals and nutrients to ground water, and promotes the acidification of ground water. Acidity, sulfate, and metals concentrations were elevated in the ground water (6- to 21-m depth) from spoil relative to unmined rock because of active oxidation of pyrite and dissolution of aluminosilicate, carbonate, and Mn-Fe-oxide minerals in the spoil. Concentrations of acidity, sulfate, metals (Fe, Mn, Al, Cd, Cu, Cr, Ni, Zn), and nitrate, and abundances of iron-oxidizing bacteria were elevated in the ground water from sludge-treated spoil relative to untreated spoil having a similar mineral composition; however, gaseous and dissolved oxygen concentrations did not differ between the treatments. Abundances of iron-oxidizing bacteria in the ground water samples were positively correlated with concentrations of ammonia, nitrate, acidity, metals, and sulfate. Concentrations of metals in vadose water samples (oxidation of pyrite by nitrate. Thus, sewage sludge added to pyritic spoil can increase the growth of iron-oxidizing bacteria, the oxidation of pyrite, and the acidification of ground water. Nevertheless, the overall effects on ground water chemistry from the sludge were small and probably short-lived relative to the effects from mining only.

  9. Pyritization processes and greigite formation in the advancing sulfidization front in the Upper Pleistocene sediments of the Black Sea

    DEFF Research Database (Denmark)

    Neretin, LN; Bottcher, ME; Jørgensen, BB

    2004-01-01

    Pyritization in late Pleistocene sediments of the Black Sea is driven by sulfide formed during anaerobic methane oxidation. A sulfidization front is formed by the opposing gradients of sulfide and dissolved iron. The sulfidization processes are controlled by the diffusion flux of sulfide from above...... and by the solid reactive iron content. Two processes of diffusion-limited pyrite formation were identified. The first process includes pyrite precipitation with the accumulation of iron sulfide precursors with the average chemical composition of FeSn (n = 1.10-1.29), including greigite. Elemental sulfur...... and polysulfides, formed from H,S by a reductive dissolution of Fe(Ill)-containing minerals, serve as intermediates to convert iron sulfides into pyrite. In the second process, a "direct" pyrite precipitation occurs through prolonged exposure of iron-containing minerals to dissolved sulfide. Methane-driven sulfate...

  10. A new approach to precious metals recovery from brown coals: Correlation of recovery efficacy with the mechanism of metal-humic interactions

    Science.gov (United States)

    Bratskaya, Svetlana Yu.; Volk, Alexandra S.; Ivanov, Vladimir V.; Ustinov, Alexander Yu.; Barinov, Nikolay N.; Avramenko, Valentin A.

    2009-06-01

    The presence of gold and platinum group elements (PGE) in low-rank brown coals around the world has promoted interest in the industrial exploitation of this alternative source of precious metals. However, due to low efficacy of the methods traditionally used for the processing of mineral ores, there exists a high demand for new strategies of precious metal recovery from refractory carbonaceous materials that could significantly increase the economic potential of gold- and PGE-bearing organic resources. Here we discuss the possibility of gold and PGE recovery from alkaline extracts of brown coals using the difference in colloidal stability of bulk organic matter and its fractions enriched with precious metals. This approach enables one to avoid complete oxidation or combustion of brown coals prior to gold recovery, to minimize organic content in gold concentrate, and to obtain a valuable by-product - humic extracts. Using gold-bearing brown coals from several deposits located in the South Far East of Russia, we show that up to 95% of gold can be transferred to alkaline extracts of humic acids (HA) and up to 85% of this gold can be recovered by centrifugation at pH 4.0-6.0, when only 5-15% of HA precipitated simultaneously. We have shown that the high efficacy of gold recovery can be attributed to the occurrence of fine-dispersed elemental gold particles stabilized by HA, which differ significantly in colloidal stability from the bulk organic matter and, thus, can be separated by centrifugation.

  11. Extensive Sorption of Organic Compounds to Black Carbon, Coal and Kerogen in Sediments and Soils: Mechanisms and Consequences for Distribution, Bioaccumulation and Biodegradation (Critical Review)

    NARCIS (Netherlands)

    Cornelissen, G.; Gustafsson, O.; Bucheli, T.D.; Jonker, M.T.O.; Koelmans, A.A.; Noort, van P.C.M.

    2005-01-01

    Evidence is accumulating that sorption of organic chemicals to soils and sediments can be described by "dual-mode sorption": absorption in amorphous organic matter (AOM) and adsorption to carbonaceous materials such as black carbon (BC), coal, and kerogen, collectively termed "carbonaceous

  12. Microbial transformation of coal and coal relevant structures - presentation of a BMBF joint research project

    Energy Technology Data Exchange (ETDEWEB)

    Sinder, C.; Schacht, S.; Pfeifer, F.; Klein, J. [DMT-Gesellschaft fuer Forschung und Pruefung mbH, Essen (Germany)

    1997-12-31

    Investigations in the joint research project `Microbial transformation of coal and coal relevant structures` supported by the Ministry of Education, Science, Research and Technology (BMBF) of the Federal Republic of Germany and coordinated by the DMT-Gesellschaft fuer Forschung und Pruefung mbH (DMT) are focussed on research and development of biotechnological coal conversion processes. Up to now investigations carried out in the project lead to a number of important results. During work on the project a great number of different microorganisms was found able to degrade or solubilize coal or lignite. Enzymatic as well as regulation mechanisms of the microbial depolymerization processes have been characterized successfully. (orig.)

  13. Oxidation of dibenzothiophene as a model substrate for the removal of organic sulphur from fossil fuels by iron(III ions generated from pyrite by Acidithiobacillus ferrooxidans

    Directory of Open Access Journals (Sweden)

    VLADIMIR P. BESKOSKI

    2007-06-01

    Full Text Available Within this paper a new idea for the removal of organically bonded sulphur from fossil fuels is discussed. Dibenzothiophene (DBT was used as a model compound of organicmolecules containing sulphur. This form of (biodesulphurization was performed by an indirect mechanism in which iron(III ions generated from pyrite by Acidithiobacillus ferrooxidans performed the abiotic oxidation. The obtained reaction products, dibenzothiopene sulfoxide and dibenzothiophene sulfone, are more soluble in water than the basic substrate and the obtained results confirmed the basic hypothesis and give the posibility of continuing the experiments related to application of this (biodesulphurization process.

  14. Pyrite nanoparticles as a Fenton-like reagent for in situ remediation of organic pollutants

    Directory of Open Access Journals (Sweden)

    Carolina Gil-Lozano

    2014-06-01

    Full Text Available The Fenton reaction is the most widely used advanced oxidation process (AOP for wastewater treatment. This study reports on the use of pyrite nanoparticles and microparticles as Fenton reagents for the oxidative degradation of copper phthalocyanine (CuPc as a representative contaminant. Upon oxidative dissolution in water, pyrite (FeS2 particles can generate H2O2 at their surface while simultaneously promoting recycling of Fe3+ into Fe2+ and vice versa. Pyrite nanoparticles were synthesized by the hot injection method. The use of a high concentration of precursors gave individual nanoparticles (diameter: 20 nm with broader crystallinity at the outer interfaces, providing a greater number of surface defects, which is advantageous for generating H2O2. Batch reactions were run to monitor the kinetics of CuPc degradation in real time and the amount of H2O2. A markedly greater degradation of CuPc was achieved with nanoparticles as compared to microparticles: at low loadings (0.08 mg/L and 20 h reaction time, the former enabled 60% CuPc removal, whereas the latter enabled only 7% removal. These results confirm that the use of low concentrations of synthetic nanoparticles can be a cost effective alternative to conventional Fenton procedures for use in wastewater treatment, avoiding the potential risks caused by the release of heavy metals upon dissolution of natural pyrites.

  15. Degradation of Anthraquinone Dye Reactive Blue 4 in Pyrite Ash Catalyzed Fenton Reaction

    Directory of Open Access Journals (Sweden)

    Milena Becelic-Tomin

    2014-01-01

    Full Text Available Pyrite ash (PA is created by burning pyrite in the chemical production of sulphuric acid. The high concentration of iron oxide, mostly hematite, present in pyrite ash, gives the basis for its application as a source of catalytic iron in a modified Fenton process for anthraquinone dye reactive blue 4 (RB4 degradation. The effect of various operating variables such as catalyst and oxidant concentration, initial pH and RB4 concentration on the abatement of total organic carbon, and dye has been assessed in this study. Here we show that degradation of RB4 in the modified Fenton reaction was efficient under the following conditions: pH=2.5; [PA]0=0.2 g L−1; [H2O2]0=5 mM and initial RB4 concentration up to 100 mg L−1. The pyrite ash Fenton reaction can overcome limitations observed from the classic Fenton reaction, such as the early termination of the Fenton reaction. Metal (Pb, Zn, and Cu content of the solution after the process suggests that an additional treatment step is necessary to remove the remaining metals from the water. These results provide basic knowledge to better understand the modified, heterogeneous Fenton process and apply the PA Fenton reaction for the treatment of wastewaters which contains anthraquinone dyes.

  16. Pyrite-pyrrhotite intergrowths in calcite marble from Bistriški Vintgar, Slovenia

    International Nuclear Information System (INIS)

    Zavašnik, J

    2016-01-01

    Roman marble quarry in Bistrica gorge in southern Pohorje Mt. (north-eastern Slovenia) is situated in a 20 m thick lens of layered marble, at the contact zone between granodiorite and metamorphites. Grey and yellowish non-homogenous calcite marble is heavily included by mica, quartz, feldspars, zoisite, pyrite and amphiboles. In the present research, we have studied numerous pyrite (FeS 2 ) crystals associated with yellowish-bronze non-stoichiometric pyrrhotite (Fe 1−x S), not previously reported from this locality. SEM investigation revealed unusual sequence of crystallisation: primary skeletal pyrrhotite matrix is sparsely overgrown by well-crystalline pyrite, both being overgrown by smaller, well-developed hexagonal pyrrhotite crystals of the second generation. With TEM we identify the pyrrhotite as 5T-Fe 1-x S phase, where x is about 0.1 and is equivalent to Fe 9 S 10 . The pyrite-pyrrhotite coexistence allows us a construction of fO 2 -pH diagram of stability fields, which reflects geochemical conditions at the time of marble re-crystallisation. (paper)

  17. Advective and diffusive contributions to reactive gas transport during pyrite oxidation in the unsaturated zone

    NARCIS (Netherlands)

    Binning, P. J.; POSTMA, D; Russell, T. F.; Wesselingh, J. A.; Boulin, P. F.

    2007-01-01

    [1] Pyrite oxidation in unsaturated mine waste rock dumps and soils is limited by the supply of oxygen from the atmosphere. In models, oxygen transport through the subsurface is often assumed to be driven by diffusion. However, oxygen comprises 23.2% by mass of dry air, and when oxygen is consumed

  18. Enhanced photoresponse of FeS2 films: the role of Marcasite-Pyrite phase junctions

    NARCIS (Netherlands)

    Wu, L.; Dzade, N.Y.; Gao, L.; Scanlon, D.O.; Öztürk, Z.; Hollingsworth, N.; Weckhuysen, B.M.; Hensen, E.J.M.; De Leeuw, N.H.; Hofmann, J.P.

    2016-01-01

    The beneficial role of marcasite in iron-sulfide-based photo-electrochemical applications is reported for the first time. A spectacular improvement of the photoresponse observed experimentally for mixed pyrite/marcasite-FeS2 films can be ascribed to the presence of p/m phase junctions at the

  19. Enhanced Photoresponse of FeS2 Films : The Role of Marcasite–Pyrite Phase Junctions

    NARCIS (Netherlands)

    Wu, Longfei; Dzade, N.Y.; Gao, L.; Scanlon, D. O.; Özturk, Zafer; Hollingsworth, N.; Weckhuysen, B.M.; Hensen, E. J. M.; de Leeuw, Nora H.; Hofmann, J. P.

    2016-01-01

    The beneficial role of marcasite in iron sulfide-based photo-electrochemical applications is reported for the first time. A spectacular improvement of the photoresponse observed experimentally for mixed pyrite/marcasite-FeS2 films can be ascribed to the presence of p/m phase junctions at the

  20. The Influence of Pyrite on the Solubility of Minjingu and Panda ...

    African Journals Online (AJOL)

    28.5 million tons of sulphur. This study was ... bining PRs with elemental S, FYM ot 'and pyrite rock rere used.in this compost (Chien et al., ... Some of the possibility of using locally available the chemical properties of the rocks materials in ...

  1. Alternative reaction routes during coal hydrogenation and coal derived oil upgrading

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, H.; Kordokuzis, G.; Langner, M. (University of Karlsruhe, Karlsruhe (Germany, F.R.). Engler-Bunte-Institute)

    1989-10-01

    Alternative reaction routes have been traced for the hydrodenitrogenation and hydrodeoxygenation of coal structure related model compounds. Reaction pathways are very structure specific. It is shown how reaction mechanisms switch from one route to another with changes in reaction conditions and catalyst features. Optimization of coal liquefaction processes can make use of this detailed understanding of selectivity. 5 refs., 7 figs.

  2. Determination of Kinetic Parameters of Coal Pyrolysis to Simulate the Process of Underground Coal Gasification (UCG

    Directory of Open Access Journals (Sweden)

    Beata Urych

    2014-01-01

    Originality/value: The devolatilization of a homogenous lump of coal is a complex issue. Currently, the CFD technique (Computational Fluid Dynamics is commonly used for the multi-dimensional and multiphase phenomena modelling. The mathematical models, describing the kinetics of the decomposition of coal, proposed in the article can, therefore, be an integral part of models based on numerical fluid mechanics.

  3. The geochemistry of environmentally important trace elements in UK coals, with special reference to the Parkgate coal in the Yorkshire-Nottinghamshire Coalfield, UK

    Science.gov (United States)

    Spears, D.A.; Tewalt, S.J.

    2009-01-01

    The Parkgate coal of Langsettian age in the Yorkshire-Nottinghamshire coalfield is typical of many coals in the UK in that it has a high sulphur (S) content. Detailed information on the distribution of the forms of S, both laterally and vertically through the seam, was known from previous investigations. In the present work, 38 interval samples from five measured sections of the coal were comprehensively analysed for major, minor and trace elements and the significance of the relationships established using both raw and centered log transformed data. The major elements are used to quantify the variations in the inorganic and organic coal components and determine the trace element associations. Pyrite contains nearly all of the Hg, As, Se, Tl and Pb and is also the major source of the Mo, Ni, Cd and Sb. The clays contain the following elements in decreasing order of association: Rb, Cs, Li, Ga, U, Cr, V, Sc, Y, Bi, Cu, Nb, Sn, Te and Th. Nearly all of the Rb is present in the clay fraction, whereas for elements such as V, Cu and U, a significant amount is thought to be present in the organic matter, based on the K vs trace element regression equations. Only Ge, and possibly Be, would appear to have a dominant organic source. The trace element concentrations are calculated for pyrite, the clay fraction and organic matter. For pyrite it is noted that concentrations agree with published data from the Yorkshire-Nottinghamshire coalfield and also that Tl concentrations (median of 0.33 ppm) in the pyrite are greater than either Hg or Cd. Unlike these elements, Tl has attracted less attention and possibly more information is needed on its anthropogenic distribution and impacts on man and the environment. A seawater source is thought to be responsible for the high concentrations of S, Cl and the non-detrital trace elements in the Parkgate coal. Indicative of the seawater control is the Th/U ratio, which expresses the detrital to non-detrital element contributions. Using

  4. Coal information 1996

    International Nuclear Information System (INIS)

    1997-01-01

    Coal Information (1997 edition) is the latest edition of a publication that has been produced annually by the IEA since 1983. The report is intended to provide both Member countries of the OECD and those employed in all sectors of the coal industry with information on current world coal market trends and long-term prospects. It includes information on coal prices, demand, trade, supply, production capacity, transport, environmental issues (including emission standards for coal-fired boilers), coal ports, coal-fired power stations and coal used in non -OECD countries. Part I of the publication contains a wide ranging review of world coal market developments in 1996 and current prospects to 2010. The review is based on historical data of OECD energy supply and demand, data on other world regions, projections of OECD coal supply, demand and trade and information provided by the CIAB. Part II provides, in tabular and graphical form, a more detailed and comprehensive statistical picture of coal developments and future prospects for coal in the OECD, by region and for individual Member countries. Readers interested in projections are strongly advised to read the notes for individual countries in Principles and Definitions in Part II. Coal statistics for non-OECD countries are presented in Part III of the book. Summary data are available on hard coal supply and end-use statistics for about 40 countries and regions world-wide. Data are based on official national submissions to the United Nations in Geneva and New York, national energy publications, information provided to the IEA Secretariat by national statistical offices as well as other unofficial Secretariat sources. Further information on coal used in non-OECD countries is published annually by the IEA in Energy Statistics and Balances of Non-OECD Countries. Also included in Part III are the Survey of Coal Ports world-wide and the Survey of Coal-fired Power Stations in coal-importing countries

  5. Study of coal flash hydropyrolysis denitrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Lihua; Zhu, Zibin; Zhu, Hongbin; Zhang, Chengfang [Research Institute of Inorganic Chemical Technology, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China)

    2003-05-15

    The hydrodenitrogenation efficiency of 14 types of coals and the reaction mechanism of Zalainouer coal were studied in an experimental entrained bed reactor by flash hydropyrolysis (FHP). The results showed that flash hydropyrolysis is an efficient method for denitrogenation, and that the denitrogenation percentage increases with an increase in temperature and hydrogen pressure. For example, the denitrogenation percentage can reach up to about 60% for Zalainouer coal at 700 C and 6.0 MPa hydrogen pressure. The denitrogenation efficiency of different coal types is related to H/C. According to the conclusion of the study, the denitrogenation percentage increases with the increase in H/C ratio, reaching about 12% when H/C is equal to 0.6, and 40-55% when H/C is above 1.0. The results indicate that FHP is an efficient technique for removing nitrogen in coal.

  6. NMR spectroscopy of coal pyrolysis products

    Energy Technology Data Exchange (ETDEWEB)

    Polonov, V.M.; Kalabin, G.A.; Kushnarev, D.F.; Shevchenko, G.G.

    1985-12-01

    The authors consider the scope for using H 1 and C 13 NMR spectroscopy to describe the products from coal pyrolysis and hydrogenization. The accuracy of the structural information provided by the best NMR methods is also considered. The stuctural parameters derived from H 1 and C 13 NMR spectra are presented. Results demonstrate the high accuracy and sensitivity of the structural information provided by H 1 AND C 13 NMR spectra for coal products. There are substantial structural differences between the soluble products from medium-temperature coking of Cheremkhov coal and high-speed pyrolysis of Kan-Acha coal, and also differences in behavior during hydrogenation. These differences are related to the structure of the organic matter in the initial coal and to differences in the pyrolysis mechanisms.

  7. Assessing the impact of preload on pyrite-rich sediment and groundwater quality.

    Science.gov (United States)

    Karikari-Yeboah, Ohene; Addai-Mensah, Jonas

    2017-02-01

    Pyrite-rich sediments would, invariably, undergo redox reactions which would lead to acidic aqueous environment containing solubilized toxic metal species. When such sediments are subjected to preload, a technique employed by geotechnical engineers to improve the load-bearing capacity of highly compressible formation, transient flow of pore water, accompanied by acidity transfer, would occur as a response. Despite the concomitant environmental and socio-economic significance, to date, there has been limited interdisciplinary research on the underpinning geotechnical engineering and geo-environmental science issues for pyrite-rich sediments under preload. In this study, we investigate the effect of pyrite-rich sediment pore water transfer under preload surcharge on the receiving environment and the impact on the groundwater speciation and quality. Sediment samples were obtained at close depth intervals from boreholes established within pristine areas and those subjected to the preload application. Soil and pore water samples were subjected to solid/solution speciation, moisture contents, soil pH and the Atterberg Limits' analyses using standard analytical techniques and methods. Standpipes were also installed in the boreholes for groundwater sampling and in situ monitoring of water quality parameters. It is shown that the imposition of preload surcharge over pyritic sediment created a reducing environment rich in SO 4 2- , iron oxide minerals and organic matter. This reducing environment fostered organic carbon catabolism to generate excess pyrite and bicarbonate alkalinity, which would invariably impact adversely on soil quality and plant growth. These were accompanied by increase in pH, dissolved Al, Ca, Mg and K species beneath the surcharge.

  8. Pyrite deformation and connections to gold mobility: Insight from micro-structural analysis and trace element mapping

    Science.gov (United States)

    Dubosq, R.; Lawley, C. J. M.; Rogowitz, A.; Schneider, D. A.; Jackson, S.

    2018-06-01

    The metamorphic transition of pyrite to pyrrhotite results in the liberation of lattice-bound and nano-particulate metals initially hosted within early sulphide minerals. This process forms the basis for the metamorphic-driven Au-upgrading model applied to many orogenic Au deposits, however the role of syn-metamorphic pyrite deformation in controlling the retention and release of Au and related pathfinder elements is poorly understood. The lower amphibolite facies metamorphic mineral assemblage (Act-Bt-Pl-Ep-Alm ± Cal ± Qz ± Ilm; 550 °C) of Canada's giant Detour Lake deposit falls within the range of pressure-temperature conditions (450 °C) for crystal plastic deformation of pyrite. We have applied a complementary approach of electron backscatter diffraction (EBSD) mapping and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) 2D element mapping on pyrite from the Detour Lake deposit. Chemical element maps document an early generation of Au-rich sieve textured pyrite domains and a later stage of syn-metamorphic oscillatory-zoned Au-poor pyrite. Both pyrite types are cut by Au-rich fractures as a consequence of remobilization of Au with trace element enrichment of first-row transition elements, post-transition metals, chalcogens and metalloids during a late brittle deformation stage. However, similar enrichment in trace elements and Au can be observed along low-angle grain boundaries within otherwise Au-poor pyrite, indicating that heterogeneous microstructural misorientation patterns and higher strain domains are also relatively Au-rich. We therefore propose that the close spatial relationship between pyrite and Au at the microscale, features typical of orogenic Au deposits, reflects the entrapment of Au within deformation-induced microstructures in pyrite rather than the release of Au during the metamorphic transition from pyrite to pyrrhotite. Moreover, mass balance calculations at the deposit scale suggest that only a small percentage

  9. Petrology, Palynology, and Geochemistry of Gray Hawk Coal (Early Pennsylvanian, Langsettian in Eastern Kentucky, USA

    Directory of Open Access Journals (Sweden)

    James C. Hower

    2015-09-01

    Full Text Available This study presents recently collected data examining the organic petrology, palynology, mineralogy and geochemistry of the Gray Hawk coal bed. From the Early Pennsylvanian, Langsettian substage, Gray Hawk coal has been mined near the western edge of the eastern Kentucky portion of the Central Appalachian coalfield. While the coal is thin, rarely more than 0.5-m thick, it has a low-ash yield and a low-S content, making it an important local resource. The Gray Hawk coal palynology is dominated by Lycospora spp., and contains a diverse spectrum of small lycopods, tree ferns, small ferns, calamites, and gymnosperms. The maceral assemblages show an abundance of collotelinite, telinite, vitrodetrinite, fusinite, and semifusinite. Fecal pellet-derived macrinite, albeit with more compaction than is typically seen in younger coals, was observed in the Gray Hawk coal. The minerals in the coal are dominated by clay minerals (e.g., kaolinite, mixed-layer illite/smectite, illite, and to a lesser extent, pyrite, quartz, and iron III hydroxyl-sulfate, along with traces of chlorite, and in some cases, jarosite, szomolnokite, anatase, and calcite. The clay minerals are of authigenic and detrital origins. The occurrence of anatase as cell-fillings also indicates an authigenic origin. With the exception of Ge and As, which are slightly enriched in the coals, the concentrations of other trace elements are either close to or much lower than the averages for world hard coals. Arsenic and Hg are also enriched in the top bench of the coal and probably occur in pyrite. The elemental associations (e.g., Al2O3/TiO2, Cr/Th-Sc/Th indicate a sediment-source region with intermediate and felsic compositions. Rare metals, including Ga, rare earth elements and Ge, are highly enriched in the coal ashes, and the Gray Hawk coals have a great potential for industrial use of these metals. The rare earth elements in the samples are weakly fractionated or are characterized by heavy

  10. Coal liquefaction technologies for producing ultra clean fuel

    International Nuclear Information System (INIS)

    Tahir, M.S.; Haq, N.U.; Nasir, H.; Islam, N.

    2011-01-01

    The expanding demand for petroleum, accompanied by the diminishing petroleum reserves and the energy security, has intensified the significance in coal liquefaction technologies (CTL) globally and specially in Pakistan. Pakistan is rich in coal resources, but short of petroleum. The Geological Survey of Pakistan based on wide spread drilling over an area of 9000 sq. km, a total of 175 billion tons of coal resource potential has been assessed. This paper overviews a general introduction on the mechanisms and processes of CLT such as direct coal liquefaction (DCL) and indirect coal liquefaction (ICL) technologies. (author)

  11. Trends in Japanese coal trade

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, S

    1986-01-01

    The author discusses 1) the latest forecast for coal demand in Japan; 2) trends in Japanese steam coal demand, with breakdown by industry; 3) the organization of steam coal supply, with details of the distribution network and of the new coal cartridge system; 4) the demand for metallurgical coal. Other topics outlined include the current status of Japanese coal production, Japanese coal trade, and the development of overseas coal resources. 1 figure, 5 tables.

  12. Influence of Pyrolysis Temperature and Type of Ligno-Cellulose and Cellulose Biomass on Yield, Specific Surface Area and Mechanical Resistance of Active Coal

    OpenAIRE

    Pohořelý, Michael

    2012-01-01

    In the Czech Republic, there are many contaminated agricultural soils due to anthropogenic activity and geogenic origin. The contaminated biomass of plants grown on the contaminated soils needs to be appropriately disposed of to prevent the re-releace of heavy metals into the environment. One way of processing contaminated biomass is pyrolysis, where the heavy metals are concentrated in biochar (active coal). This can be applied to soil where it improves the physical properties. The aim of ...

  13. Contents and occurrence of cadmium in the coals from Guizhou province, China.

    Science.gov (United States)

    Song, Dangyu; Wang, Mingshi; Zhang, Junying; Zheng, Chuguang

    2008-10-01

    Eleven raw coal samples were collected from Liuzhi, Suicheng, Zunyi, Xingren, Xingyi, and Anlong districts in Guizhou Province, Southwest China. The content of cadmium (Cd) in coal was determined using inductively coupled plasma mass-spectrometry (ICP-MS). Cd contents ranged from 0.146 to 2.74 ppm (whole coal basis), with an average of 1.09 ppm. In comparison with the arithmetic means of Cd in Chinese coal (0.25 ppm), this is much higher. In order to find its occurrence in coal, float-sink analysis and a coal flotation test by progressive release were conducted on two raw coal samples. The content of the Cd and ash yield of the flotation products were determined. The organic matter was removed by low-temperature ashing (LTA). X-ray diffraction (XRD) was used to differentiate the main, minor, and trace minerals in the LTA from different flotation subproducts. Quartz, kaolinite, pyrite, and calcite were found to dominate the mineral matters, with a proportion of anatase, muscovite, and illite. Then quantitative analysis of minerals in LTA was conducted using material analysis using diffraction (MAUD) based on the Rietveld refinement method. Results show that Cd has a strong association with kaolinite.

  14. Contents and occurrence of cadmium in the coals from Guizhou Province, China

    Energy Technology Data Exchange (ETDEWEB)

    Dangyu Song; Mingshi Wang; Junying Zhang; Chuguang Zheng [Henan Polytechnic University, Jiaozuo (China). Institute of Resources and Environment

    2008-10-15

    Eleven raw coal samples were collected from Liuzhi, Suicheng, Zunyi, Xingren, Xingyi, and Anlong districts in Guizhou Province, Southwest China. The content of cadmium (Cd) in coal was determined using inductively coupled plasma mass-spectrometry (ICP-MS). Cd contents ranged from 0.146 to 2.74 ppm (whole coal basis), with an average of 1.09 ppm. In comparison with the arithmetic means of Cd in Chinese coal (0.25 ppm), this is much higher. In order to find its occurrence in coal, float-sink analysis and a coal flotation test by progressive release were conducted on two raw coal samples. The content of the Cd and ash yield of the flotation products were determined. The organic matter was removed by low-temperature ashing (LTA). X-ray diffraction (XRD) was used to differentiate the main, minor, and trace minerals in the LTA from different flotation subproducts. Quartz, kaolinite, pyrite, and calcite were found to dominate the mineral matters, with a proportion of anatase, muscovite, and illite. Then quantitative analysis of minerals in LTA was conducted using material analysis using diffraction (MAUD) based on the Rietveld refinement method. Results show that Cd has a strong association with kaolinite.

  15. Mineralogical and Geochemical Compositions of the No. 5 Coal in Chuancaogedan Mine, Junger Coalfield, China

    Directory of Open Access Journals (Sweden)

    Ning Yang

    2015-11-01

    Full Text Available This paper reports the mineralogy and geochemistry of the Early Permian No. 5 coal from the Chuancaogedan Mine, Junger Coalfield, China, using optical microscopy, scanning electron microscopy (SEM, Low-temperature ashing X-ray diffraction (LTA-XRD in combination with Siroquant software, X-ray fluorescence (XRF, and inductively coupled plasma mass spectrometry (ICP-MS. The minerals in the No. 5 coal from the Chuancaogedan Mine dominantly consist of kaolinite, with minor amounts of quartz, pyrite, magnetite, gypsum, calcite, jarosite and mixed-layer illite/smectite (I/S. The most abundant species within high-temperature plasma-derived coals were SiO2 (averaging 16.90%, Al2O3 (13.87%, TiO2 (0.55% and P2O5 (0.05%. Notable minor and trace elements of the coal include Zr (245.89 mg/kg, Li (78.54 mg/kg, Hg (65.42 mg/kg, Pb (38.95 mg/kg, U (7.85 mg/kg and Se (6.69 mg/kg. The coal has an ultra-low sulfur content (0.40%. Lithium, Ga, Se, Zr and Hf present strongly positive correlation with ash yield, Si and Al, suggesting they are associated with aluminosilicate minerals in the No. 5 coal. Arsenic is only weakly associated with mineral matter and Ge in the No. 5 coals might be of organic and/or sulfide affinity.

  16. Environmental geochemistry of acid mine drainage water at Indus coal mine at Lakhra, Sindh Pakistan

    International Nuclear Information System (INIS)

    Siddique, I.; Shah, M.T.

    2000-01-01

    The annual coal production of Pakistan is about 3,637, 825 tones which is about 6% of the country's energy resources, out of this 1,241, 965 tones of coal was produced/ mined from the Lakhra coal field, District Dadu, Sindh which after the Thar coal field is the second largest coal field of Pakistan. At this coal field more than 58 mining companies are engaged in exploring the hidden wealth of the country. The problem of acid mine drainage, is caused by the passage or seepage of water, through mines where iron disulfides, usually pyrites, are exposed to the oxidizing action of water, air and bacteria, is the main problem faced by the mining companies. The geochemical analysis of acid mine drainage water collected from Indus coal mine no. 6 shows that beside its higher pH, total Dissolved Solids and Sulfates, it also posses higher amount of heavy metals like Cd, Cu, Pb, Co, Ni and Fe. This acid mine drainage water not only damages the mine structures but is also harmful to soil and ecology. (author)

  17. Electric plants to gas, influence of both Mineral Matter and Air Oxidation in coal pyrolysis

    International Nuclear Information System (INIS)

    Mondragon, F.; Jaramillo, A.; Quintero, G.

    1995-01-01

    In this work some coal samples from different Colombia's deposits are analyzed. In first stage, material matter is removed from coal by acid treatment with HF/HCl, and aerial oxidation of coal is made with air in oven to 150 Centigrade degree temperature. In second stage, pyrolysis is carried out in two different techniques: 1. Thermogravimetric Analysis (TGA) and 2. Programmed Temperature Pyrolysis (PTP) in a pyrolyzer equipped with a quadrupole mass spectrometer. In both techniques, the coal samples are heated in different rates to 650 Centigrade degree. During PTP trials the evolution of CH4, H2S, hydrocarbons (m/z=42), CO2, benzene and toluene are monitored. Studied coal samples showed: 1). A gas conversion range between 48.8% to 21.8%; 2). A decrease in the gas conversion between 2% to 4%, when oxidation it is applied; 3). The temperature at the one which is presented the maximum evolution of CH4 is similar for all coal samples; 4). The maximum evolution of H2S depends on mineral matter composition, occurs between 480 to 550 Centigrade degrees and is presented due to pyrite decomposition. 5). The evolution of CO2 occurs between 100 to 650 Centigrade degree, its production is generated in different stage of the mentioned temperature range, and in some coal samples is presented due to inorganic origin

  18. Nitrogen in Chinese coals

    Science.gov (United States)

    Wu, D.; Lei, J.; Zheng, B.; Tang, X.; Wang, M.; Hu, Jiawen; Li, S.; Wang, B.; Finkelman, R.B.

    2011-01-01

    Three hundred and six coal samples were taken from main coal mines of twenty-six provinces, autonomous regions, and municipalities in China, according to the resource distribution and coal-forming periods as well as the coal ranks and coal yields. Nitrogen was determined by using the Kjeldahl method at U. S. Geological Survey (USGS), which exhibit a normal frequency distribution. The nitrogen contents of over 90% Chinese coal vary from 0.52% to 1.41% and the average nitrogen content is recommended to be 0.98%. Nitrogen in coal exists primarily in organic form. There is a slight positive relationship between nitrogen content and coal ranking. ?? 2011 Science Press, Institute of Geochemistry, CAS and Springer Berlin Heidelberg.

  19. Coal marketing manual 1986

    Energy Technology Data Exchange (ETDEWEB)

    1986-01-01

    This manual presents information for the use of marketers, consumers, analysts and investors. The information is presented in a series of tables and figures. Statistics are given for: Australian export tonnages and average export values for 1978-1985; international pig iron production 1976 to 1985; and international crude steel production 1979 to 1985. Trends in Australian export tonnages and prices of coal are reviewed. Details of international loading and discharge ports are given, together with a historical summary of shipping freight-rates since 1982. Long term contract prices for thermal and coking coal to Japan are tabulated. A review of coal and standards is given, together with Australian standards for coal and coke. A section on coal quality is included containing information on consumer coal quality preferences and Australian and Overseas coal brands and qualities. Finally an index is given of contact details of Australian and Overseas exporting companies, government departments, and the Australian Coal Association.

  20. Coal worker's pneumoconiosis

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000130.htm Coal worker's pneumoconiosis To use the sharing features on this page, please enable JavaScript. Coal worker's pneumoconiosis (CWP) is a lung disease that ...

  1. Development of world coal reserves, their registration and their utilization

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, H

    1979-10-01

    This paper examines statistics on world coal production and world coal reserves with figures from 1860 to 1974 provided in tables and graphs. Eighty percent of the total world coal reserves (92% of world brown coal reserves) lie in the USA and USSR. The recent increase in total coal reserve estimates is due to exploration in western USA and in the USSR east of the Urals. Depth and thickness of the world's coal seams are shown in graphs and variations in coal quality are discussed. Problems associated with the anticipated substantial increase in coal production up to the year 2000 are considered. Encouraging higher coal production is the successful development of highly mechanized underground mining techniques and highly productive heavy surface mining equipment which allows excavation at increased depths. Surface mining is expected to make up 50% of total world mining operations in the near future. More complete deposit exploitation also contributes to higher coal production. Low international ship freight rates would facilitate future world coal trade. Obstacles are seen as: high, long term investments due to the fact that coal reserves lie far from populated and industrialized areas; opening new mines; transportation costs and infrastructure development.

  2. Carbonation as a binding mechanism for coal/calcium hydroxide pellets. Final technical report, 1 September, 1992--31 August, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, D.; Lytle, J.; Hackley, K.; Dagamac, M. [Illinois State Geological Survey, Champaign, IL (United States); Berger, R. [Univ. of Illinois, Urbana, IL (United States); Schanche, G. [Army Construction Engineering Research Lab., Champaign, IL (United States)

    1993-12-31

    This research was an investigation of calcium hydroxide, a sulfur-capturing sorbent, as a binder for coal fines. The reaction of carbon dioxide with calcium hydroxide, referred to as carbonation, was studied as a method for improving pellet quality. Carbonation forms a cementitious matrix of calcium carbonate. Research has demonstrated that calcium hydroxide is a viable binder for coal fines and that a roller-and-die pellet mill is an effective method of pellet formation. From a minus 28 mesh preparation plant fine coal sample, a roller-and-die pellet mill produced strong pellets when 5 and 10% calcium hydroxide was used as a binder. The pellets containing 10% calcium hydroxide strengthened considerably when air cured. This increase in strength was attributed to carbonation via atmospheric carbon dioxide. Pellets containing 10 wt% calcium hydroxide were produced using an extruder but pellets formed in this manner were much weaker than pellets produced with the roller-and-die mill. In tests performed using a laboratory hydraulic press, the effect of particle size and compaction pressure on pellet strength was studied. Particle distributions with mean sizes of 200, 90 and 40 microns were tested. The results indicate that pellet strength increased with decreasing particle size and increasing compaction pressure when calcium hydroxide was used as a binder. Pellets containing 10 wt% calcium hydroxide increased in strength by approximately 40% when air dried for one day. As above, this increase in strength was attributed to carbonation of the calcium hydroxide via atmospheric carbon dioxide.

  3. Moessbauer and XRD Characterization of the Mineral Matter of Coal from the Guachinte Mine in Colombia

    International Nuclear Information System (INIS)

    Reyes, F.; Perez Alcazar, G. A.; Barraza, J. M.; Bohorquez, A.; Tabares, J. A.; Speziali, N. L.

    2003-01-01

    The aim of this work was the characterization and differentiation, using Moessbauer spectroscopy (MS) and X-ray diffraction (XRD), of coal samples with different ash and sulfur contents obtained in three places corresponding at cuts in different seams from the Guachinte mine, Valle, Colombia. The mineral phases identified by XRD were in general kaolinite, quartz, pyrite and gypsum, and in particular dolomite and calcite. MS confirms the presence of pyrite and kaolinite, besides evidences the additional presence of jarosite which was not detected by the XRD results due their low amounts. In the high mineral matter ash sample quartz and hematite was identified by XRD, the last one confirmed by MS results. A second phase in this sample was detected by Moessbauer spectroscopy, which could be superparamagnetic hematite. Rietveld refinement for XRD pattern from a sample is reported.

  4. Japan`s sunshine project. 17.. 1992 annual summary of coal liquefaction and gasification

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-01

    This report describes the achievement of coal liquefaction and gasification technology development in the Sunshine Project for FY 1992. It presents the research and development of coal liquefaction which includes studies on reaction mechanism of coal liquefaction and catalysts for coal liquefaction, the research and development of coal gasification technologies which includes studies on gasification characteristics of various coals and improvement of coal gasification efficiency, the development of bituminous coal liquefaction which includes engineering, construction and operation of a bituminous coal liquefaction pilot plant and research by a process supporting unit (PSU), the development of brown coal liquefaction which includes research on brown coal liquefaction with a pilot plant and development of techniques for upgrading coal oil from brown coal, the development of common base technologies which includes development of slurry letdown valves and study on upgrading technology of coal-derived distillates, the development of coal-based hydrogen production technology with a pilot plant, the development of technology for entrained flow coal gasification, the assessment of coal hydrogasification, and the international co-operation. 4 refs., 125 figs., 39 tabs.

  5. Bioprocessing of lignite coals using reductive microorganisms. Final technical report, September 30, 1988--March 29, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, D.L.

    1992-03-29

    In order to convert lignite coals into liquid fuels, gases or chemical feedstock, the macromolecular structure of the coal must be broken down into low molecular weight fractions prior to further modification. Our research focused on this aspect of coal bioprocessing. We isolated, characterized and studied the lignite coal-depolymerizing organisms Streptomyces viridosporus T7A, Pseudomonas sp. DLC-62, unidentified bacterial strain DLC-BB2 and Gram-positive Bacillus megaterium strain DLC-21. In this research we showed that these bacteria are able to solubilize and depolymerize lignite coals using a combination of biological mechanisms including the excretion of coal solublizing basic chemical metabolites and extracellular coal depolymerizing enzymes.

  6. Fording Canadian Coal Trust

    Energy Technology Data Exchange (ETDEWEB)

    Popowich, J.; Millos, R. [Elk Valley Coal Corporation, Calgary, AB (Canada)

    2004-07-01

    This is the first of five slide/overhead presentations presented at the Fording Canadian Coal Trust and Tech Cominco Ltd. investor day and mine tour. The Fording Canadian Coal Trust is described. The Trust's assets comprise six Elk Valley metallurgical coal mines and six wollastonite operations (in the NYCO Group). Trust structure, corporate responsibility, organizational structure, reserves and resources, management philosophy, operating strategies, steel market dynamics, coal market, production expansion, sales and distribution are outlined. 15 figs., 5 tabs.

  7. Coal. [1987 and 1989

    Energy Technology Data Exchange (ETDEWEB)

    1988-06-01

    Despite increases in recently negotiated coal prices in US dollar terms, unit export returns for Australian coal are expected to rise only marginally in 1988-89 due to the anticipated appreciation of the Australian dollar. Australian coal production is expected to recover in 1988-89, after falling in 1987-88. A table summarising coal statistics in 1985-