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.

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

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.

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.

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.

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

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.

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.

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%.

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.

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.

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.

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.

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.

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)

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.

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.)

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.

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.

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)

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.

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.

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.

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.

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.

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.

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.

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.

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)

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.

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

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.

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

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.

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.

Final Report of the Advanced Coal Technology Work Group

Science.gov (United States)

The Advanced Coal Technology workgroup reported to the Clean Air Act Advisory Committee. This page includes the final report of the Advanced Coal Technology Work Group to the Clean Air Act Advisory Committee.

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.

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.

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)

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

Energy Technology Data Exchange (ETDEWEB)

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.

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.

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

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.

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.

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

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.

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.

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.

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)

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.

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

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

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

Pre-Concentration of Vanadium from Stone Coal by Gravity Using Fine Mineral Spiral

Directory of Open Access Journals (Sweden)

Xin Liu

2016-08-01

Full Text Available Due to the low grade of V2O5 in stone coal, the existing vanadium extraction technologies face challenges in terms of large handling capacity, high acid consumption and production cost. The pre-concentration of vanadium from stone coal before the extraction process is an effective method to reduce cost. In this study, detailed mineral characterization of stone coal was investigated. It has been confirmed that the vanadium mainly occurs in muscovite and illite. A significant demand for an effective pre-concentration process with simple manipulation for discarding quartz and other gangue minerals is expected. Based on the mineralogical study, a new vanadium pre-concentration process using a fine mineral spiral was investigated. The experimental results showed that the separation process, which was comprised of a rougher and scavenger, could efficiently discard quartz, pyrite and apatite. A final concentrate with V2O5 grade of 1.02% and recovery of 89.6% could be obtained, with 26.9% of the raw ore being discarded as final tailings.

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.

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.

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.

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.

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

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

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

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.

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

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

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)

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.

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

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.

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.

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

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

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)...

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.

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 (...

Pelletization of fine coals. Final report

Energy Technology Data Exchange (ETDEWEB)

Sastry, K.V.S.

1995-12-31

Coal is one of the most abundant energy resources in the US with nearly 800 million tons of it being mined annually. Process and environmental demands for low-ash, low-sulfur coals and economic constraints for high productivity are leading the coal industry to use such modern mining methods as longwall mining and such newer coal processing techniques as froth flotation, oil agglomeration, chemical cleaning and synthetic fuel production. All these processes are faced with one common problem area--fine coals. Dealing effectively with these fine coals during handling, storage, transportation, and/or processing continues to be a challenge facing the industry. Agglomeration by the unit operation of pelletization consists of tumbling moist fines in drums or discs. Past experimental work and limited commercial practice have shown that pelletization can alleviate the problems associated with fine coals. However, it was recognized that there exists a serious need for delineating the fundamental principles of fine coal pelletization. Accordingly, a research program has been carried involving four specific topics: (i) experimental investigation of coal pelletization kinetics, (ii) understanding the surface principles of coal pelletization, (iii) modeling of coal pelletization processes, and (iv) simulation of fine coal pelletization circuits. This report summarizes the major findings and provides relevant details of the research effort.

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.

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.

THE DEPRESSION OF PYRITE FLOTATION BY THIOBACILLUS FERROOXIDANS

Institute of Scientific and Technical Information of China (English)

无

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.

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.

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.

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.

Deposit Formation during Coal-Straw Co-Combustion in a Utility PF-Boiler

DEFF Research Database (Denmark)

Andersen, Karin Hedebo

1998-01-01

the combustion conditions, including the method of introduction of the straw to the boiler, as well as the amount of Fe introduced as Pyrite with the coal.No significant effect could be found in the deposition probe samples for an increase in probe metal temperature from 540°C to 620°C. The importance of deposit...... area. The evaluation was performed for an opposed-wall fired and tangentially fired boiler, which are compared to the wall-fired MKS1. Two major aspects were evaluated: The effect of flue gas temperatures and the effect of mixing. However, no final recommandation for choise of boilertype can be given...

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.

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.)

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.

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

EXPERIMENTS AND COMPUTATIONAL MODELING OF PULVERIZED-COAL IGNITION; FINAL

International Nuclear Information System (INIS)

Samuel Owusu-Ofori; John C. Chen

1999-01-01

Under typical conditions of pulverized-coal combustion, which is characterized by fine particles heated at very high rates, there is currently a lack of certainty regarding the ignition mechanism of bituminous and lower rank coals as well as the ignition rate of reaction. furthermore, there have been no previous studies aimed at examining these factors under various experimental conditions, such as particle size, oxygen concentration, and heating rate. Finally, there is a need to improve current mathematical models of ignition to realistically and accurately depict the particle-to-particle variations that exist within a coal sample. Such a model is needed to extract useful reaction parameters from ignition studies, and to interpret ignition data in a more meaningful way. The authors propose to examine fundamental aspects of coal ignition through (1) experiments to determine the ignition temperature of various coals by direct measurement, and (2) modeling of the ignition process to derive rate constants and to provide a more insightful interpretation of data from ignition experiments. The authors propose to use a novel laser-based ignition experiment to achieve their first objective. Laser-ignition experiments offer the distinct advantage of easy optical access to the particles because of the absence of a furnace or radiating walls, and thus permit direct observation and particle temperature measurement. The ignition temperature of different coals under various experimental conditions can therefore be easily determined by direct measurement using two-color pyrometry. The ignition rate-constants, when the ignition occurs heterogeneously, and the particle heating rates will both be determined from analyses based on these measurements

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.)

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.

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

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.)

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

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)

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

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

Selenium transformation in coal mine spoils: Its environmental impact assessment. Final report

Energy Technology Data Exchange (ETDEWEB)

Harness, J.; Atalay, A.; Koll, K.J.; Zhang, H.; Maggon, D.

1991-12-31

The objective of this program was to conduct an environmental impact assessment study for selenium from coal mine spoils. The use of in-situ lysimetry to predict selenium speciation, transformation, and mobility under natural conditions was evaluated. The scope of the study was to construct and test field-scale lysimeter and laboratory mini-column to assess mobility and speciation of selenium in coal mine overburden and soil systems; to conduct soil and groundwater sampling throughout the state of Oklahoma for an overall environmental impact assessment of selenium; and to conduct an in-depth literature review on the solubility, speciation, mobility, and toxicity of selenium from various sources. Groundwater and surface soil samples were also collected from each county in Oklahoma. Data collected from the lysimeter study indicated that selenium in the overburden of the abandoned mine site was mainly found in the selenite form. The amount of selenite found was too low and immobile to be of concern to the environment. The spoil had equilibrated long enough (over 50 years) that most of the soluble forms of selenium have already been lost. Examination of the overburden indicated the presence of pyrite crystals that precipitated over time. The laboratory mini-column study indicated that selenite is quite immobile and remained on the overburden material even after leaching with dilute acid. Data from groundwater samples indicated that based on the current permissible level for selenium in groundwater (0.01 mg Se/L), Oklahoma groundwater is widely contaminated with the element. However, according to the new regulation (0.05 mg Se/L), which is to be promulgated in 1992, only 9 of the 77 counties in the state exceed the limit.

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.

Nuclear techniques in the coal industry. Proceedings of a final research co-ordination meeting

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-11-01

With the aim of promoting advanced research and facilitating a more extensive application of nuclear techniques for environmental protection in the exploration and exploitation of coal, the IAEA established the present co-ordinated research programme (CRP) in 1989. This report includes an assessment of the current status and trends in nuclear techniques in the coal industry and the results obtained by the participants at the CRP. Proceedings of the final CRP on ``Nuclear Techniques in Exploration and Exploitation of Coal: On-line and Bulk Analysis and Evaluation of Potential Environmental Pollutants in Coal and Coke``, was held in Krakow, Poland, from 9 to 12 May 1994. Refs, figs, tabs.

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.

Characterization and evaluation of washability of Alaskan coals: Fifty selected seams from various coal fields: Final technical report, September 30, 1976-February 28, 1986. [50 coal seams

Energy Technology Data Exchange (ETDEWEB)

Rao, P.D.

1986-09-01

This final report is the result of a study initiated in 1976 to obtain washability data for Alaskan coals, to supplement the efforts of the US Department of Energy in their ongoing studies on washability of US coals. Washability characteristics were determined for fifty coal samples from the Northern Alaska, Chicago Creek, Unalakleet, Nenana, Matanuska, Beluga, Yentna and Herendeen Bay coal fields. The raw coal was crushed to 1-1/2 inches, 3/8 inch, 14 mesh and 65 mesh top sizes, and float-sink separations were made at 1.30, 1.40 and 1.60 specific gravities. A limited number of samples were also crushed to 200 and 325 mesh sizes prior to float-sink testing. Samples crushed to 65 mesh top size were also separated at 1.60 specific gravity and the float and sink products were characterized for proximate and ultimate analyses, ash composition and ash fusibility. 72 refs., 79 figs., 57 tabs.

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.

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.

Coal combustion aerothermochemistry research. Final report

Energy Technology Data Exchange (ETDEWEB)

Witte, A.B.; Gat, N.; Denison, M.R.; Cohen, L.M.

1980-12-15

On the basis of extensive aerothermochemistry analyses, laboratory investigations, and combustor tests, significant headway has been made toward improving the understanding of combustion phenomena and scaling of high swirl pulverized coal combustors. A special attempt has been made to address the gap between scientific data available on combustion and hardware design and scaling needs. Both experimental and theoretical investigations were conducted to improve the predictive capability of combustor scaling laws. The scaling laws derived apply to volume and wall burning of pulverized coal in a slagging high-swirl combustor. They incorporate the findings of this investigation as follows: laser pyrolysis of coal at 10/sup 6/ K/sec and 2500K; effect of coal particle shape on aerodynamic drag and combustion; effect of swirl on heat transfer; coal burnout and slag capture for 20 MW/sub T/ combustor tests for fine and coarse coals; burning particle trajectories and slag capture; particle size and aerodynamic size; volatilization extent and burnout fraction; and preheat level. As a result of this work, the following has been gained: an increased understanding of basic burning mechanisms in high-swirl combustors and an improved model for predicting combustor performance which is intended to impact hardware design and scaling in the near term.

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.

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.

Wabash River Coal Gasification Repowering Project: A DOE Assessment; FINAL

International Nuclear Information System (INIS)

National Energy Technology Laboratory

2002-01-01

The goal of the U.S. Department of Energy (DOE) Clean Coal Technology Program (CCT) is to furnish the energy marketplace with a number of advanced, more efficient, and environmentally responsible coal utilization technologies through demonstration projects. These projects seek to establish the commercial feasibility of the most promising advanced coal technologies that have developed beyond the proof-of-concept stage. This document serves as a DOE post-project assessment (PPA) of a project selected in CCT Round IV, the Wabash River Coal Gasification Repowering (WRCGR) Project, as described in a Report to Congress (U.S. Department of Energy 1992). Repowering consists of replacing an existing coal-fired boiler with one or more clean coal technologies to achieve significantly improved environmental performance. The desire to demonstrate utility repowering with a two-stage, pressurized, oxygen-blown, entrained-flow, integrated gasification combined-cycle (IGCC) system prompted Destec Energy, Inc., and PSI Energy, Inc., to form a joint venture and submit a proposal for this project. In July 1992, the Wabash River Coal Gasification Repowering Project Joint Venture (WRCGRPJV, the Participant) entered into a cooperative agreement with DOE to conduct this project. The project was sited at PSI Energy's Wabash River Generating Station, located in West Terre Haute, Indiana. The purpose of this CCT project was to demonstrate IGCC repowering using a Destec gasifier and to assess long-term reliability, availability, and maintainability of the system at a fully commercial scale. DOE provided 50 percent of the total project funding (for capital and operating costs during the demonstration period) of$438 million. Construction for the demonstration project was started in July 1993. Pre-operational tests were initiated in August 1995, and construction was completed in November 1995. Commercial operation began in November 1995, and the demonstration period was completed in December

Chemical Interactions of Hydraulic Fracturing Biocides with Natural Pyrite

Science.gov (United States)

Consolazio, Nizette A.

In conjunction with horizontal drilling, hydraulic fracturing or fracking has enabled the recovery of natural gas from low permeable shale formations. In addition to water, these fracking fluids employ proppants and up to 38 different chemical additives to improve the efficiency of the process. One important class of additives used in hydraulic fracturing is biocides. When applied appropriately, they limit the growth of harmful microorganisms within the well, saving energy producers 4.5 billion dollars each year. However, biocides or their harmful daughter products may return to the surface in produced water, which must then be appropriately stored, treated and disposed of. Little is known about the effect of mineral-fluid interactions on the fate of the biocides employed in hydraulic fracturing. In this study, we employed laboratory experiments to determine changes in the persistence and products of these biocides under controlled environments. While many minerals are present in shale formations, pyrite, FeS2(s) is particularly interesting because of its prevalence and reactivity. The FeII groups on the face of pyrite may be oxidized to form FeIII phases. Both of these surfaces have been shown to be reactive with organic compounds. Chlorinated compounds undergo redox reactions at the pyrite-fluid interface, and sulfur-containing compounds undergo exceptionally strong sorption to both pristine and oxidized pyrite. This mineral may significantly influence the degradation of biocides in the Marcellus Shale. Thus, the overall goal of this study was to understand the effect of pyrite on biocide reactivity in hydraulic fracturing, focusing on the influence of pyrite on specific functional groups. The first specific objective was to demonstrate the effect of pyrite and pyrite reaction products on the degradation of the bromine-containing biocide, DBNPA. On the addition of pyrite to DBNPA, degradation rates of the doubly brominated compound were found to increase

Recovery of Rare Earth Elements from Coal and Coal Byproducts via a Closed Loop Leaching Process: Final Report

Energy Technology Data Exchange (ETDEWEB)

Peterson, Richard [Battelle Memorial Inst., Columbus, OH (United States); Heinrichs, Michael [Battelle Memorial Inst., Columbus, OH (United States); Argumedo, Darwin [Battelle Memorial Inst., Columbus, OH (United States); Taha, Rachid [Battelle Memorial Inst., Columbus, OH (United States); Winecki, Slawomir [Battelle Memorial Inst., Columbus, OH (United States); Johnson, Kathryn [Battelle Memorial Inst., Columbus, OH (United States); Lane, Ann [Battelle Memorial Inst., Columbus, OH (United States); Riordan, Daniel [Battelle Memorial Inst., Columbus, OH (United States)

2017-08-31

REEs using the ADP technology. In AOI 1, Ohio coal sources with the potential to provide a consistent source of rare earth element concentrations above 300 parts per million will be identified. Coal sample inventories from West Virginia and Pennsylvania will also be assessed for purposes of comparison. Three methods of preparing the coal ash will be evaluated for their potential to enhance the technical feasibility and economics of REE recovery. Three sources of coal ash are targeted for evaluation of the economics of REE recovery in this project: (1) coal ash from power generation stations, to include fly ash and/or bottom ash, (2) ash generated in a lower temperature ashing process, and (3) ash residual from Battelle’s coal liquefaction process. Making use of residual ash from coal liquefaction processes directly leverages work currently being conducted by Battelle for DOE NETL in response to DE-FOA-0000981 entitled “Greenhouse Gas Emissions Reductions Research and Development Leading to Cost-Competitive Coal-to-Liquids Based Jet Fuel Production.” Using the sample characterization results and regional information regarding REE concentration, availability and cost, a TEA will be developed. The previously generated laboratory testing results for leaching and REE recovery via the ADP will be used to perform the TEA, along with common engineering assumptions for scale up of equipment and labor costs. Finally, upon validation of the economic feasibility of the process by the TEA, limited laboratory testing will be performed to support the design of a bench scale system. In a future project phase, it is envisioned that the bench scale system will be constructed and operated to prove the process on a continuous basis.

Coal rebounds for the final quarter

Energy Technology Data Exchange (ETDEWEB)

Soras, C.; Stodden, J.

1987-11-01

Coal production in the USA is up 0.3% by the end of September 1987 from the pace of one year ago. Most impressive has been the growth in demand at power plants where coal consumption is up by 13.5 million tons through the month of July. The coal markets turnabout is based upon the entire economic spectrum not upon a single large market. US steel mills represent intense power consuming activities as do the US chemicals, plastics, paper and pulp industries.

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

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.

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.

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.

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

E-commerce finally finds the coal industry

Energy Technology Data Exchange (ETDEWEB)

Hudson, M.

2000-12-01

In the last few months, new web sites have come online which are not only showcase for coal mining products and equipment but also act as sales platforms. A large set of sites deal with the purchase of coal and other raw materials. Most of them offer 24-hour news updates, a coal library and a reference section to help with financing, insurance and transportation of purchased coal. Another group focuses on the sale of equipment. Short writeups are given of 18 web sites. 1 photo.

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.

Formation and retention of methane in coal. Final report

Energy Technology Data Exchange (ETDEWEB)

Hucka, V.J.; Bodily, D.M.; Huang, H.

1992-05-15

The formation and retention of methane in coalbeds was studied for ten Utah coal samples, one Colorado coal sample and eight coal samples from the Argonne Premium Coal Sample Bank.Methane gas content of the Utah and Colorado coals varied from zero to 9 cm{sup 3}/g. The Utah coals were all high volatile bituminous coals. The Colorado coal was a gassy medium volatile bituminous coal. The Argonne coals cover a range or rank from lignite to low volatile bituminous coal and were used to determine the effect of rank in laboratory studies. The methane content of six selected Utah coal seams and the Colorado coal seam was measured in situ using a special sample collection device and a bubble desorbometer. Coal samples were collected at each measurement site for laboratory analysis. The cleat and joint system was evaluated for the coal and surrounding rocks and geological conditions were noted. Permeability measurements were performed on selected samples and all samples were analyzed for proximate and ultimate analysis, petrographic analysis, {sup 13}C NMR dipolar-dephasing spectroscopy, and density analysis. The observed methane adsorption behavior was correlated with the chemical structure and physical properties of the coals.

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.

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

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.

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.

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

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.

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.

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

Molecular accessibility in solvent swelled coals. Final report

Energy Technology Data Exchange (ETDEWEB)

Kispert, L.D.

1994-04-01

The conversion of coal by an economically feasible catalytic method requires the catalyst to diffuse into the coal sample so that hydrogenation catalysis can occur from within as well as the normal surface catalysis. Thus an estimate of the size, shape, and reactivity, of the pores in the coal before and after the swelling with different solvents is needed so that an optimum sized catalyst will be used. This study characterizes the accessible area found in Argonne Premium Coal Samples (APCS) using a EPR spin probe technique. The properties deduced in this manner correlate well with the findings deduced from SANS, NMR, SEM, SAXS and light scattering measurements. The use of nitroxide spin probes with swelling solvents is a simple way in which to gain an understanding of the pore structure of coals, how it changes in the presence of swelling solvents and the chemistry that occurs at the pore wall. Hydrogen bonding sites occur primarily in low-rank coals and vary in reactive strength as rank is varied. Unswelled coals contain small, spherical pores which disappear when coal is swelled in the presence of polar solvents. Swelling studies of polystyrene-divinyl benzene copolymers implied that coal is polymeric, contains significant quantities of covalent cross-links and the covalent cross-link density increases with rank.

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.

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.

Petrography and geochemistry of Oligocene bituminous coal from the Jiu Valley, Petrosani basin (southern Carpathian Mountains), Romania

Energy Technology Data Exchange (ETDEWEB)

Belkin, Harvey E.; Tewalt, Susan J. [U.S. Geological Survey, 956 National Center, Reston, VA 20192 (United States); Hower, James C. [University of Kentucky Center for Applied Energy Research, 2540 Research Park Drive, Lexington, KY 40511 (United States); Stucker, J.D. [University of Kentucky Center for Applied Energy Research, 2540 Research Park Drive, Lexington, KY 40511 (United States); University of Kentucky Department of Earth and Environmental Sciences, Lexington, KY 40506 (United States); O' Keefe, Jennifer M.K. [Morehead State University, Morehead, KY, 40351 (United States); Tatu, Calin A. [University of Medicine and Pharmacy, Department of Immunology, Clinical Laboratory No. 1, Pta. E. Murgu No. 2, RO-1900 Timisoara (Romania); Buia, Grigore [University of Petrosani, Department of Geology, University St. 20, RO-2675 Petrosani (Romania)

2010-05-01

Belt samples of Oligocene (Chattian) bituminous coal from 10 underground mines located in the Jiu Valley, Hunedoara County, Petrosani basin, Romania, have been examined and analyzed for proximate and ultimate analysis, major-, minor- and trace-element chemistry, organic petrography, and vitrinite reflectance. The mineral chemistry and mode of occurrence of trace elements also have been investigated using SEM and electron microprobe techniques. Twenty coal beds occur in the Jiu Valley and most of the samples are from bed no. 3, the most productive bed of the Dilja-Uricani Formation of Oligocene age. The Petrosani basin, oriented SW-NE, is 48-km long, 10-km wide at the eastern part and 2-km wide at the western part. The coal mines are distributed along the center of the valley generally following the Jiu de Vest River. Reflectance measurements indicate that the rank of the coals ranges from high-volatile B to high-volatile A bituminous. Overall, rank decreases from the southwest to the northeast. In bed no. 3, R{sub max} varies from 0.75% in the northeast to 0.93% in the southwest. Although, most Oligocene coals in Romania and adjacent countries are lignite in rank, the Jiu Valley bituminous coals have been affected by regional metamorphism and attending hydrothermal fluids related to the Alpine orogenic event. The coals are all dominated by vitrinite; resinite and funginite are important minor macerals in most of the coals. Pyrite and carbonate generally dominate the mineral assemblages with carbonate more abundant in the northwest. Siderite occurs as nodules and masses within the macerals (generally vitrinite). Dolomite and calcite occur as fracture fillings, plant-cell fillings, and in other authigenic forms. Late-stage fracture fillings are siderite, dolomite, calcite, and ankerite. In one instance, two populations of siderite ({proportional_to} 35 and {proportional_to} 45 wt.% FeO) plus ankerite fill a large fracture. Late-stage pyrite framboid alteration is Ni

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.

Toxic substances from coal combustion -- A comprehensive assessment

Energy Technology Data Exchange (ETDEWEB)

Senior, C.L.; Huggins, F.E.; Huffman, G.P.; Shan, N.; Yap, N.; Wendt, J.O.L.; Seames, W.; Ames, M.R.; Sarofim, A.F.; Swenson, S.; Lighty, J.; Kolker, A.; Finkelman, R.; Palmer, C.; Mroczkowski, S.; Helble, J.; Mamani-Paco, R.; Sterling, R.; Dunham, G.; Miller, S.

2000-08-17

The final program review meeting of Phase II was held on June 22 in Salt Lake City. The goals of the meeting were to present work in progress and to identify the remaining critical experiments or analyses, particularly those involving collaboration among various groups. The information presented at the meeting is summarized in this report. Remaining fixed bed, bench-scale experiments at EERC were discussed. There are more ash samples which can be run. Of particular interest are high carbon ash samples to be generated by the University of Arizona this summer and some ash-derived sorbents that EERC has evaluated on a different program. The use of separation techniques (electrostatic or magnetic) was also discussed as a way to understand the active components in the ash with respect to mercury. XAFS analysis of leached and unleached ash samples from the University of Arizona was given a high priority. In order to better understand the fixed bed test results, CCSEM and Moessbauer analyses of those ash samples need to be completed. Utah plans to analyze the ash from the single particle combustion experiments for those major elements not measured by INAA. USGS must still complete mercury analyses on the whole coals and leaching residues. Priorities for further work at the SHRIMP-RG facility include arsenic on ash surfaces and mercury in sulfide minerals. Moessbauer analyses of coal samples from the University of Utah were completed; samples from the top and bottom layers of containers of five different coals showed little oxidation of pyrite in the top relative to the bottom except for Wyodak.

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)

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.

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.

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 ...

Low severity conversion of activated coal. Final report

Energy Technology Data Exchange (ETDEWEB)

Hirschon, A.S.; Ross, D.S.

1990-01-01

The results suggest that coal contains regions with structural components significantly reactive under the hydrothermal environment. Although the specific mechanism for this process remains to be developed, this activity is reminiscent of findings in studies of accelerated maturation of oil shale, where hydrothermal treatment (hydrous pyrolysis) leads to the production of petroleum hydrocarbons. In line with what has been seen in the oil shale work, the pretreatment-generated hydrocarbons and phenols appear to represent a further or more complete maturation of some fraction of the organic material within the coal. These observations could have an impact in two areas. The first is in the area of coal structure, where immature, reactive regions have not been included in the structures considered at present. The second area of interest is the more practical one of conversions to coal liquids and pyrolytic tars. It seems clear that the hydrothermal pretreatment changes the coal in some manner that favorably affects the product quality substantially and, as in the CO/water liquefaction case, favorably affects the yields. The conversions of coals of lower rank, i.e., less mature coals, could particularly benefit in terms of both product quality and product quantity. The second portion of this project also shows important benefits to coal conversion technology. It deals with synthesizing catalysts designed to cleave the weak links in the coal structure and then linking these catalysts with the pretreatment methods in Task 2. The results show that highly dispersed catalysts can effectively be used to increase the yields of soluble material. An important aspect of highly dispersed catalysts are that they can effectively catalyze coal conversion even in poor liquefaction solvents, thus making them very attractive in processes such as coprocessing where inexpensive liquefaction media such as resids are used.

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.

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

Healy Clean Coal Project: Healy coal firing at TRW Cleveland Test Facility. Final report

Energy Technology Data Exchange (ETDEWEB)

Koyama, T.; Petrill, E.; Sheppard, D.

1991-08-01

A test burn of two Alaskan coals was conducted at TRW`s Cleveland test facility in support of the Healy Clean Coal Project, as part of Clean Coal Technology III Program in which a new power plant will be constructed using a TRW Coal Combustion System. This system features ash slagging technology combined with NO{sub x} and SO{sub x} control. The tests, funded by the Alaska Industrial Development and Export Authority (AIDEA) and TRW, were conducted to verify that the candidate Healy station coals could be successfully fired in the TRW coal combustor, to provide data required for scale-up to the utility project size requirements, and to produce sufficient flash-calcined material (FCM) for spray dryer tests to be conducted by Joy/NIRO. The tests demonstrated that both coals are viable candidates for the project, provided the data required for scale-up, and produced the FCM material. This report describes the modifications to the test facility which were required for the test burn, the tests run, and the results of the tests.

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.

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

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

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.

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

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.

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.

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.

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

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

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.

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

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.

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

Fundamental study for improvement of dewatering of fine coal/refuse. Final report, August 1981-December 1984

Energy Technology Data Exchange (ETDEWEB)

Chiang, S.H.; Klinzing, G.E.; Morsi, B.I.; Tierney, J.W.; Binkley, T.; Chi, S.M.; Huang, S.; Qamar, I.; Venkatadri, R.

1984-12-01

Fine coal in slurry form must be dewatered to minimize handling and transportation problems and be reduced to a desirable level for subsequent preparation of coal/water mixtures as a substitute utility fuel. The current practice is inadequate for the dewatering of fine coal, particularly for coal particles with sizes smaller than 400 mesh. Therefore, it is most desirable to develop improved mechanical methods for reducing the moisture content of fine coal. In the light of this, a fundamental study of the dewatering of fine coal/refuse was initiated in June 1979 and continued through 1984. The overall objective of the study is to seek improved methods of dewatering through a better understanding of the filtration and post-filtration processes. As a first step, efforts have been focused on the mechanism of dewatering in terms of the basic properties of coal (and refuse) particles and the microstructures of filter cakes, and their relations to filtration rate and final moisture content. Pittsburgh seam-Bruceton Mine coal was used as a base coal. During the past year, filter cakes from coals with widely varying size ranges were micrographically characterized. The effects of a number of surface active agents and of entrapped air bubbles on the filter cake properties were also studied. Modules of the network model for calculating single phase and two phase permeabilities were formulated and tested. The report is divided into four parts: summary and deliverables; work forecast for 1984-1985; detailed description of technical progress; and appendices. 21 refs., 55 figs., 17 tabs.

Wyoming coal-conversion project. Final technical report, November 1980-February 1982. [Proposed WyCoalGas project, Converse County, Wyoming; contains list of appendices with title and identification

Energy Technology Data Exchange (ETDEWEB)

None

1982-01-01

This final technical report describes what WyCoalGas, Inc. and its subcontractors accomplished in resolving issues related to the resource, technology, economic, environmental, socioeconomic, and governmental requirements affecting a project located near Douglas, Wyoming for producing 150 Billion Btu per day by gasifying sub-bituminous coal. The report summarizes the results of the work on each task and includes the deliverables that WyCoalGas, Inc. and the subcontractors prepared. The co-venturers withdrew from the project for two reasons: federal financial assistance to the project was seen to be highly uncertain; and funds were being expended at an unacceptably high rate.

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.

Coal surface structure and thermodynamics. Final report

Energy Technology Data Exchange (ETDEWEB)

Larsen, J.W.; Wernett, P.C.; Glass, A.S.; Quay, D.; Roberts, J.

1994-05-01

Coals surfaces were studied using static surface adsorption measurements, low angle x-ray scattering (LAXS), inverse gas chromatography (IGC) and a new {sup 13}C NMR relaxation technique. A comparison of surface areas determined by hydrocarbon gas adsorption and LAXS led to the twin conclusions that the hydrocarbons had to diffuse through the solid to reach isolated pores and that the coal pores do not form interconnected networks, but are largely isolated. This conclusion was confirmed when IGC data for small hydrocarbons showed no discontinuities in their size dependence as usually observed with porous solids. IGC is capable of providing adsorption thermodynamics of gases on coal surfaces. The interactions of non-polar molecules and coal surfaces are directly proportioned to the gas molecular polarizability. For bases, the adsorption enthalpy is equal to the polarizability interaction plus the heat of hydrogen bond formation with phenol. Amphoteric molecules have more complex interactions. Mineral matter can have highly specific effects on surface interactions, but with most of the molecules studied is not an important factor.

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.

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

Heterotrophic Bioleaching of Sulfur, Iron, and Silicon Impurities from Coal by Fusarium oxysporum FE and Exophiala spinifera FM with Growing and Resting Cells.

Science.gov (United States)

Etemadzadeh, Shekoofeh Sadat; Emtiazi, Giti; Etemadifar, Zahra

2016-06-01

Coal is the most abundant fossil fuel containing sulfur and other elements which promote environmental pollution after burning. Also the silicon impurities make the transportation of coal expensive. In this research, two isolated fungi from oil contaminated soil with accessory number KF554100 (Fusarium oxysporum FE) and KC925672 (Exophiala spinifera FM) were used for heterotrophic biological leaching of coal. The leaching were detected by FTIR, CHNS, XRF analyzer and compared with iron and sulfate released in the supernatant. The results showed that E. spinifera FM produced more acidic metabolites in growing cells, promoting the iron and sulfate ions removal while resting cells of F. oxysporum FE enhanced the removal of aromatic sulfur. XRF analysis showed that the resting cells of E. spinifera FM proceeded maximum leaching for iron and silicon (48.8, 43.2 %, respectively). CHNS analysis demonstrated that 34.21 % of sulfur leaching was due to the activities of resting cells of F. oxysporum FE. Also F. oxysporum FE removed organic sulfur more than E. spinifera FM in both growing and resting cells. FTIR data showed that both fungi had the ability to remove pyrite and quartz from coal. These data indicated that inoculations of these fungi to the coal are cheap and impurity removals were faster than autotrophic bacteria. Also due to the removal of dibenzothiophene, pyrite, and quartz, we speculated that they are excellent candidates for bioleaching of coal, oil, and gas.

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

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.

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)

Gold and trace element zonation in pyrite using a laser imaging technique: Implications for the timing of gold in orogenic and carlin-style sediment-hosted deposits

Science.gov (United States)

Large, R.R.; Danyushevsky, L.; Hollit, C.; Maslennikov, V.; Meffre, S.; Gilbert, S.; Bull, S.; Scott, R.; Emsbo, P.; Thomas, H.; Singh, B.; Foster, J.

2009-01-01

Laser ablation ICP-MS imaging of gold and other trace elements in pyrite from four different sediment- hosted gold-arsenic deposits has revealed two distinct episodes of gold enrichment in each deposit: an early synsedimentary stage where invisible gold is concentrated in arsenian diagenetic pyrite along with other trace elements, in particular, As, Ni, Pb, Zn, Ag, Mo, Te, V, and Se; and a later hydrothermal stage where gold forms as either free gold grains in cracks in overgrowth metamorphic and/or hydrothermal pyrite or as narrow gold- arsenic rims on the outermost parts of the overgrowth hydrothermal pyrite. Compared to the diagenetic pyrites, the hydrothermal pyrites are commonly depleted in Ni, V, Zn, Pb, and Ag with cyclic zones of Co, Ni, and As concentration. The outermost hydrothermal pyrite rims are either As-Au rich, as in moderate- to high- grade deposits such as Carlin and Bendigo, or Co-Ni rich and As-Au poor as in moderate- to low-grade deposits such as Sukhoi Log and Spanish Mountain. The early enrichment of gold in arsenic-bearing syngenetic to diagenetic pyrite, within black shale facies of sedimentary basins, is proposed as a critical requirement for the later development of Carlin-style and orogenic gold deposits in sedimentary environments. The best grade sediment-hosted deposits appear to have the gold climax event, toward the final stages of deformation-related hydrothermal pyrite growth and fluid flow. ?? 2009 Society of Economic Geologists, Inc.

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.

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.

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

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.

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.

Technical data. Final technical report, November 1980-May 1982. [Proposed WyCoalGas project, Converse County, Wyoming

Energy Technology Data Exchange (ETDEWEB)

None

1982-01-01

This volume includes a description of the railway to transport the coal; possible unbalance in the electrical power supply is considered in detail, as well as communications, signalling, etc. The railway will also be used to transport ashes and sludges for waste disposal. Coal fines in the coal supply will be burned to generate power. A very brief description of the coal gasification plant and its components is accompanied by a printout of the dates final engineering is to be completed. Permit applications are listed and socio-economic factors are discussed. The financing plan is discussed in some detail: basically, a loan guarantee from the Synthetic Fuels Corporation; equity provided by investment tax credit, deferred taxes, AFUDC and the sponsors; price support; and gas purchase agreement (this whole section includes several legal details.). (LTN)

National Coal Utilization Assessment: a preliminary assessment of coal utilizaton in the South. [Southern USA to 2020; forecasting

Energy Technology Data Exchange (ETDEWEB)

Berry, L. B.; Bjornstad, D. J.; Boercker, F. D.

1978-01-01

Some of the major problems and issues related to coal development and use in the South are identified and assessed assuming a base-case energy scenario for the next 45 years. This scenario assumes a midrange of coal use and a relatively high rate of nuclear use over the forecast period. The potential impacts from coal development and use are significant, particularly in the 1990-2020 time period. Practically all available sites suitable for power plant development in the assessment will be utilized by 2020. Overall, sulfur dioxide will be well below the annual primary standard; however, several local hot-spot areas were identified. In addition, sulfate concentrations will be increased significantly, particularly over Virginia, West Virginia, and northern Kentucky. Coal mining is expected to affect 6 of the 12 major ecological regions. Coal mining will lead to increased average suspended sediment concentrations in some river basins, and special measures will be required to control acid discharges from active mines in pyritic regions. The increased mining of coal and subsequent sulfur dioxide increases from its combustion may also give rise to a land-use confrontation with food and fiber production. Potential health effects from exposure to sulfur dioxide and sulfates are expected to increase rapidly in several areas, particularly in parts of Kentucky, Maryland, District of Columbia, and Georgia. Regional social costs should be relatively low, although some site-specific costs are expected to be very high. Alternative energy technologies, careful siting selection, and deployment of environmental control technologies and operating policies will be required to reduce or mitigate these potential impacts.

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

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.

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

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)

Mathematical modelling of demineralisation of high sulphur coal by bioleaching

Energy Technology Data Exchange (ETDEWEB)

Weerasekara, N.S.; Frutos, F.J.G.; Cara, J.; Lockwood, F.C. [University of London Imperial College of Science Technology & Medicine, London (United Kingdom)

2008-02-15

During coal combustion various toxic compounds are generated from its sulphur content. Their environmental impacts are considered to be very important. While there are various conventional preparation methods to remove the sulphur in the fuel, recent work reveals that newly-isolated micro-organisms, naturally present in coal, have the ability to reduce its sulphur content. The removal of sulphur using biological leaching involving acidophilic iron oxidising bacteria like Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans are examined and a computational technique based on computational fluid dynamics is developed to model the biological leaching of sulphur from coal. The model was validated against a pack-column experiment carried out for iron separation during 60 days. The mathematical model predicted iron separation over time is similar to experimental measurements, with an average difference of 5.5%. According to the experimental results, there was an overall reduction of 33% of pyrite, whereas the model prediction was 32%. The model results shows overall good agreement with pack-column experimental data.

Nuclear assay of coal. Volume 6. Mass flow devices for coal handling. Final report

International Nuclear Information System (INIS)

Gozani, T.; Elias, E.; Bevan, R.

1980-04-01

The mass of coal entering the boiler per unit time is an essential parameter for determining the total rate of heat input. The mass flow rate of coal on a conveyor belt is generally determined as a product of the instantaneous mass of material on a short section of the belt and the belt velocity. Belt loading could be measured by conventional transducers incorporating mechanical or electromechanical weighers or by gamma-ray attenuation gauge. This report reviews the state of the art in mass flow devices for coal handling. The various methods are compared and commented upon. Special design issues are discussed relative to incorporating a mass flow measuring device in a Continuous On-Line Nuclear Analysis of Coal (CONAC) system

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−.

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.

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.

Effects of pyrite and sphalerite on population compositions, dynamics and copper extraction efficiency in chalcopyrite bioleaching process.

Science.gov (United States)

Xiao, Yunhua; Liu, Xueduan; Dong, Weiling; Liang, Yili; Niu, Jiaojiao; Gu, Yabing; Ma, Liyuan; Hao, Xiaodong; Zhang, Xian; Xu, Zhen; Yin, Huaqun

2017-07-01

This study used an artificial microbial community with four known moderately thermophilic acidophiles (three bacteria including Acidithiobacillus caldus S1, Sulfobacillus thermosulfidooxidans ST and Leptospirillum ferriphilum YSK, and one archaea, Ferroplasma thermophilum L1) to explore the variation of microbial community structure, composition, dynamics and function (e.g., copper extraction efficiency) in chalcopyrite bioleaching (C) systems with additions of pyrite (CP) or sphalerite (CS). The community compositions and dynamics in the solution and on the ore surface were investigated by real-time quantitative PCR (qPCR). The results showed that the addition of pyrite or sphalerite changed the microbial community composition and dynamics dramatically during the chalcopyrite bioleaching process. For example, A. caldus (above 60%) was the dominant species at the initial stage in three groups, and at the middle stage, still dominated C group (above 70%), but it was replaced by L. ferriphilum (above 60%) in CP and CS groups; at the final stage, L. ferriphilum dominated C group, while F. thermophilum dominated CP group on the ore surface. Furthermore, the additions of pyrite or sphalerite both made the increase of redox potential (ORP) and the concentrations of Fe 3+ and H + , which would affect the microbial community compositions and copper extraction efficiency. Additionally, pyrite could enhance copper extraction efficiency (e.g., improving around 13.2% on day 6) during chalcopyrite bioleaching; on the contrary, sphalerite restrained it.

Modelling temperature-dependent heat production over decades in High Arctic coal waste rock piles

DEFF Research Database (Denmark)

Hollesen, Jørgen; Elberling, Bo; Jansson, P.E.

2011-01-01

Subsurface heat production from oxidation of pyrite is an important process that may increase subsurface temperatures within coal waste rock piles and increase the release of acid mine drainage, AMD. Waste rock piles in the Arctic are especially vulnerable to changes in subsurface temperatures...... such as heat production from coal oxidation may be equally important....... as the release of AMD normally is limited by permafrost. Here we show that temperatures within a 20 year old heat-producing waste rock pile in Svalbard (78°N) can be modelled by the one-dimensional heat and water flow model (CoupModel) with a new temperature-dependent heat-production module that includes both...

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)

Mössbauer study of Fe mineralogy with respect to rank, type and Colombian carboniferous zone

International Nuclear Information System (INIS)

Caballero, F. Reyes; Martínez Ovalle, S. A.; Díaz Lagos, M.; Gómez, O. P.; Blandón, A.

2017-01-01

The transmission mode of Fe-57 Mössbauer spectroscopy was used to identify iron bearing minerals and establish relationships between and among these minerals and the ranks and types of various carboniferous zones in Colombia. Maceral and mineral compositions vary significantly among Colombian carboniferous zones. These variations determine some of the final characteristics and potential uses of coal, and therefore significantly contribute to defining coal quality. A comparison of spectroscopy results shows that the thermal maturity of the Colombian coals ranges from lignite to semianthracite. Similarities and differences exist with respect to conventional parameters. The coals of Córdoba and Cauca have higher sulfur contents > 2 % ash contents. Iron bearing minerals identified included pyrite, which was, found everywhere, and illite, ankerite, siderite, iron sulfates were found in particular areas. Coals from Valle del Cauca, Córdoba, Caldas and Santander are characterized by oxidation of pyrite and its transformation into ferrous or ferric sulfate.

Mössbauer study of Fe mineralogy with respect to rank, type and Colombian carboniferous zone

Energy Technology Data Exchange (ETDEWEB)

Caballero, F. Reyes, E-mail: carefa4@hotmail.com; Martínez Ovalle, S. A., E-mail: s.agustin.martinez@uptc.edu.co [Universidad Pedagógica y Tecnológica de Colombia, Grupo de Física Nuclear Aplicada y Simulación (Colombia); Díaz Lagos, M., E-mail: mercedes.diaz@uptc.edu.co [Universidad Pedagógica y Tecnológica de Colombia, Escuela de Ingeniería Geológica (Colombia); Gómez, O. P., E-mail: olgapatricia.gomez@uptc.edu.co [Universidad Pedagógica y Tecnológica de Colombia, Escuela de Ingeniería de Minas (Colombia); Blandón, A., E-mail: asblando@unal.edu.co [Universidad Nacional de Colombia, Departamento de Materiales y Minerales, Facultad de Minas (Colombia)

2017-11-15

The transmission mode of Fe-57 Mössbauer spectroscopy was used to identify iron bearing minerals and establish relationships between and among these minerals and the ranks and types of various carboniferous zones in Colombia. Maceral and mineral compositions vary significantly among Colombian carboniferous zones. These variations determine some of the final characteristics and potential uses of coal, and therefore significantly contribute to defining coal quality. A comparison of spectroscopy results shows that the thermal maturity of the Colombian coals ranges from lignite to semianthracite. Similarities and differences exist with respect to conventional parameters. The coals of Córdoba and Cauca have higher sulfur contents > 2 % ash contents. Iron bearing minerals identified included pyrite, which was, found everywhere, and illite, ankerite, siderite, iron sulfates were found in particular areas. Coals from Valle del Cauca, Córdoba, Caldas and Santander are characterized by oxidation of pyrite and its transformation into ferrous or ferric sulfate.

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.

Applied research and evaluation of process concepts for liquefaction and gasification of western coals. Final report

Energy Technology Data Exchange (ETDEWEB)

Wiser, W. H.

1980-09-01

Fourteen sections, including five subsections, of the final report covering work done between June 1, 1975 to July 31, 1980 on research programs in coal gasification and liquefaction have been entered individually into EDB and ERA. (LTN)

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.

CATALYTIC GASIFICATION OF COAL USING EUTECTIC SALT MIXTURES; FINAL

International Nuclear Information System (INIS)

Dr. Yaw D. Yeboah; Dr. Yong Xu; Dr. Atul Sheth; Dr. Pradeep Agrawal

2001-01-01

The Gas Research Institute (GRI) estimates that by the year 2010, 40% or more of U.S. gas supply will be provided by supplements including substitute natural gas (SNG) from coal. These supplements must be cost competitive with other energy sources. The first generation technologies for coal gasification e.g. the Lurgi Pressure Gasification Process and the relatively newer technologies e.g. the KBW (Westinghouse) Ash Agglomerating Fluidized-Bed, U-Gas Ash Agglomerating Fluidized-Bed, British Gas Corporation/Lurgi Slagging Gasifier, Texaco Moving-Bed Gasifier, and Dow and Shell Gasification Processes, have several disadvantages. These disadvantages include high severities of gasification conditions, low methane production, high oxygen consumption, inability to handle caking coals, and unattractive economics. Another problem encountered in catalytic coal gasification is deactivation of hydroxide forms of alkali and alkaline earth metal catalysts by oxides of carbon (CO(sub x)). To seek solutions to these problems, a team consisting of Clark Atlanta University (CAU, a Historically Black College and University, HBCU), the University of Tennessee Space Institute (UTSI) and Georgia Institute of Technology (Georgia Tech) proposed to identify suitable low melting eutectic salt mixtures for improved coal gasification. The research objectives of this project were to: Identify appropriate eutectic salt mixture catalysts for coal gasification; Assess agglomeration tendency of catalyzed coal; Evaluate various catalyst impregnation techniques to improve initial catalyst dispersion; Determine catalyst dispersion at high carbon conversion levels; Evaluate effects of major process variables (such as temperature, system pressure, etc.) on coal gasification; Evaluate the recovery, regeneration and recycle of the spent catalysts; and Conduct an analysis and modeling of the gasification process to provide better understanding of the fundamental mechanisms and kinetics of the process

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.

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...

Potential for thermal coal and Clean Coal Technology (CCT) in the Asia-Pacific. Final technical report

Energy Technology Data Exchange (ETDEWEB)

Johnson, C.J.; Long, S.

1991-11-22

The Coal Project was able to make considerable progress in understanding the evolving energy situation in Asia and the future role of coal and Clean Coal Technologies. It is clear that there will be major growth in consumption of coal in Asia over the next two decades -- we estimate an increase of 1.2 billion metric tons. Second, all governments are concerned about the environmental impacts of increased coal use, however enforcement of regulations appears to be quite variable among Asian countries. There is general caution of the part of Asian utilities with respect to the introduction of CCT`s. However, there appears to be potential for introduction of CCT`s in a few countries by the turn of the century. It is important to emphasize that it will be a long term effort to succeed in getting CCT`s introduced to Asia. The Coal Project recommends that the US CCT program be expanded to allow the early introduction of CCT`s in a number of countries.

Characterization of desulfurization, denitrogenation and process sulfur transfer during hydropyrolysis of Chinese high sulfur coals

Energy Technology Data Exchange (ETDEWEB)

Sun Chenggong; Li Baoqing [Chinese Academy of Sciences, Taiyuan (China). State Key Lab. of Coal Conversion; Snape, C.E. [Strathclyde Univ., Glasgow (United Kingdom). Dept. of Pure and Applied Chemistry

1997-12-31

The process desulphurization and denitrogenation of Chinese high sulfur coals and the characteristics of sulfur transformation during non-catalytic hydropyrolysis were investigated by a 10 g fixed-bed reactor and a small-scaled reactor with online spectrometry respectively. It was indicated that more than 70% of the total sulfur of the two high sulfur coals and almost all pyritic sulfur are removed as H{sub 2}S, leaving the char and tar products with much less sulfur distribution. The liability of sulfur transformation to tar products is closely related to the thiophenic structure forms rather than sulfidic forms. At the same time, the formation of trace amount of sulfur dioxide indicates the presence of inherent sulfur oxidation reactions inside coal frame structures even under H{sub 2} pressure. (orig.)

Depositional environments of the Jurassic Maghara main coal seam in north central Sinai, Egypt

Science.gov (United States)

Edress, Nader Ahmed Ahmed; Opluštil, Stanislav; Sýkorová, Ivana

2018-04-01

Twenty-eight channel samples with a cumulative thickness of about 4 m collected from three sections of the Maghara main coal seam in the middle Jurassic Safa Formation have been studied for their lithotype and maceral compositions to reconstruct the character of peat swamp, its hydrological regime and the predominating type of vegetation. Lithotype composition is a combination of dully lithotypes with duroclarain (19% of total cumulative thickness), clarodurain (15%), black durain (15%), and shaly coal (15%) and bright lithotypes represented by clarain (23%), vitrain (12%) and a small proportion of wild fire-generated fusain (1%). Maceral analyses revealed the dominance of vitrinite (70.6% on average), followed by liptinite (25.2%) and inertinite (8.1%). Mineral matter content is ∼9% on average and consists of clay, quartz and pyrite concentrate mostly at the base and the roof of the seam. Dominantly vitrinite composition of coal and extremely low fire- and oxidation-borne inertinite content, together with high Gelification Indices imply predomination of waterlogged anoxic conditions in the precursing mire with water tables mostly above the peat surface throughout most of the time during peat swamp formation. Increases in collotelinite contents and Tissue Preservation Index up the section, followed by a reversal trend in upper third of the coal section, further accompanied by a reversal trend in collodetrinite, liptodetrinite, alginite, sporinite and clay contents records a transition from dominately limnotelmatic and limnic at the lower part to dominately limnotelmatic with increase telmatic condition achieved in the middle part of coal. At the upper part of coal seam an opposite trend marks the return to limnic and limnotelmatic conditions in the final phases of peat swamp history and its subsequent inundation. The proportion of arborescent (mostly coniferous) and herbaceous vegetation varied throughout the section of the coal with tendency of increasing

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.

Fiscal 1993 report. Coal liquefaction committee; 1993 nendo sekitan ekika iinkai hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-03-01

The committee in this fiscal year had the 1st meeting in July 1993, the 2nd in December 1993, and the 3rd in March 1994, when fiscal 1993 research and development programs and results were reported and discussed. Reported and discussed at the 2nd meeting were the compilation of brown coal liquefaction technology development project results, evaluation report on the same, hydrorefining of oil from brown coal and the research and development of application technologies for the same, and an environmental safety evaluation test on the same. In selecting a standard coal for the operation of the 150 ton/day pilot plant, PSU (process supporting unit)-aided studies were made on the analytical values presented by coals, yield of the liquid, yield of the liquefaction residue, yield of the generated gas, amount of the hydrogen consumed, coal oil properties, liquefaction residue properties, operationality, etc. On-site investigations were conducted also in Indonesia, and a conclusion was reached that Tanito Harum coal would be the most suitable for the pilot plant. Concerning the liquefaction catalyst for the pilot plant, a report was given on a comparison made between the activity of a synthetic iron sulfide and that of natural pyrite. (NEDO)

Final Safety Assessment of Coal Tar as Used in Cosmetics

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

Coal Tar is a semisolid by-product obtained in the destructive distillation of bituminous coal, which functions in cosmetic products as a cosmetic biocide and denaturant-antidandruff agent is also listed as a function, but this is considered an over-the-counter (OTC) drug use. In 2002, Coal Tar was reported to the Food and Drug Administration (FDA) to be used in four formulations, all of which appear to be OTC drug products. Coal Tar is monographed by the FDA as Category I (safe and effective) OTC drug ingredient for use in the treatment of dandruff, seborrhoea, and psoriasis. Coal Tar is absorbed through the skin of animals and humans and is systemically distributed. Although the Cosmetic Ingredient Review (CIR) Expert Panel believes that Coal Tar use as an antidandruff ingredient in OTC drug preparations is adequately addressed by the FDA regulations, the Panel also believes that the appropriate concentration of use of Coal Tar in cosmetic formulations should be that level that does not have a biological effect in the user. Additional data needed to make a safety assessment include product types in which Coal Tar is used (other than as an OTC drug ingredient), use concentrations, and the maximum concentration that does not induce a biological effect in users.

Development of enhanced sulfur rejection processes

Energy Technology Data Exchange (ETDEWEB)

Yoon, R.H.; Luttrell, G.H.; Adel, G.T.; Richardson, P.E.

1996-03-01

Research at Virginia Tech led to the development of two complementary concepts for improving the removal of inorganic sulfur from many eastern U.S. coals. These concepts are referred to as Electrochemically Enhanced Sulfur Rejection (EESR) and Polymer Enhanced Sulfur Rejection (PESR) processes. The EESR process uses electrochemical techniques to suppress the formation of hydrophobic oxidation products believed to be responsible for the floatability of coal pyrite. The PESR process uses polymeric reagents that react with pyrite and convert floatable middlings, i.e., composite particles composed of pyrite with coal inclusions, into hydrophilic particles. These new pyritic-sulfur rejection processes do not require significant modifications to existing coal preparation facilities, thereby enhancing their adoptability by the coal industry. It is believed that these processes can be used simultaneously to maximize the rejection of both well-liberated pyrite and composite coal-pyrite particles. The project was initiated on October 1, 1992 and all technical work has been completed. This report is based on the research carried out under Tasks 2-7 described in the project proposal. These tasks include Characterization, Electrochemical Studies, In Situ Monitoring of Reagent Adsorption on Pyrite, Bench Scale Testing of the EESR Process, Bench Scale Testing of the PESR Process, and Modeling and Simulation.

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

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.)

Whole rock and discrete pyrite geochemistry as complementary tracers of ancient ocean chemistry: An example from the Neoproterozoic Doushantuo Formation, China

Science.gov (United States)

Gregory, Daniel D.; Lyons, Timothy W.; Large, Ross R.; Jiang, Ganqing; Stepanov, Aleksandr S.; Diamond, Charles W.; Figueroa, Maria C.; Olin, Paul

2017-11-01

windows of opportunity. For example, unlike the potential vulnerability of whole rock data to secondary alteration, the pyrite record may survive greenschist facies metamorphism. Furthermore, early-formed pyrite can be identified through textural relationships as a proxy of primary marine chemistry even in the presence of hydrothermal overprints on whole rock chemistry via secondary fluids. Finally, pyrite analyses may allow for the possibility of more quantitative interpretations of the ancient ocean once the elemental partitioning between the mineral and host fluids are better constrained. Collectively, these advances can greatly increase the number of basins that may be investigated for early ocean chemistry, especially those of Precambrian age.

Geochemistry of Early Frasnian (Late Devonian) pyrite-ammonoid level in the Kostomłoty Basin, Poland, and a new proxy parameter for assessing the relative amount of syngenetic and diagenetic pyrite

Science.gov (United States)

Pisarzowska, Agnieszka; Berner, Zsolt A.; Racki, Grzegorz

2014-07-01

Pyrite geochemistry (isotope and trace element composition, degree of pyritization, S/Corg ratio) was used in context of selected lithogeochemical parameters (major and trace elements, including sulphur, organic carbon, and δ13C of carbonate carbon) to constrain fluctuations in depositional conditions during the Early to Middle Frasnian carbon isotopic perturbation (punctata Event) in the Kostomłoty Basin, Poland. Based on the ratio between the sum of oxyanionic elements and transition metals in pyrite, a new proxy parameter (index of syngenetic pyrite, ISYP) is proposed for assessing the relative amount of syngenetic pyrite in a sample. The distribution of the ISYP along the Kostomłoty - Małe Górki section (upper Szydłówek to the basal Kostomłoty beds) is in concert with conclusions inferred from paleoecologic data and other geochemical parameters (degree of pyritization, S/Corg, δ34Spyrite). According to these, the lower segment of the Szydłówek Beds was deposited in a normally oxygenated environment, but undergoing increasing primary productivity in surface water, as indicated by an increase in δ13Ccarb and in Cu/Zr ratio in bulk rock, which triggered the periodic deposition of sediments slightly enriched in organic matter, notably within the pyrite-ammonoid level (= Goniatite Level). Fluctuating, but in general high S/Corg ratios, DOPR values and ISYP values suggest that during this time - against the background of a generally dysoxic environment - shorter or longer lasting episodes of more restricted (anoxic and possibly even euxinic) bottom water conditions developed. Low sedimentation rates enabled a continuous and practically unlimited supply of sulphate during bacterial sulphate reduction (BSR), which in turn led to a strong depletion of pyrite sulphur in 34S in this interval (constantly around -29‰). In contrast, below and above the Goniatite Level, higher δ34S values (up to + 3‰), are compatible with closed system conditions and higher

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.

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

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

Quantification of mineral matter in commercial cokes and their parent coals

Energy Technology Data Exchange (ETDEWEB)

Sakurovs, Richard; French, David; Grigore, Mihaela [CRC for Coal in Sustainable Development, CSIRO Energy Technology, PO Box 330 Newcastle 2300 (Australia)

2007-10-01

The nature of mineral matter in coke is an important factor in determining the behaviour of coke in the blast furnace. However, there have been few quantitative determinations of the types of mineral matter in coke and the feed coal. Here we use a technique of quantitative X-ray diffraction - SIROQUANT trademark - to determine the nature and quantity of mineral matter in eleven cokes and their parent materials, using samples of coals and their cokes utilised commercially in blast furnaces around the world. In some of these coals a considerable proportion of the phosphorus was present as goyazite, an aluminium phosphate. In the cokes, most of the iron was incorporated into amorphous aluminosilicate material; metallic iron accounted for about 15% of the iron present, and a similar amount was present as sulfides. Potassium and sodium were largely present as amorphous aluminosilicate material. Most of the quartz in the coal was unaffected by the coking, but a small fraction was transformed into other minerals. Quartz is not completely inert during coking. The amount of the catalytic forms of iron in the coke - iron, iron oxides and iron sulfides - was not related to the amount of pyrite and siderite in the starting coal, indicating that estimation of catalytic iron requires investigation of the mineral matter in coke directly and cannot be estimated from the minerals in the coal. (author)

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

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

Chemical kinetics and transport processes in supercritical fluid extraction of coal. Final report, August 10, 1990--December 30, 1992

Energy Technology Data Exchange (ETDEWEB)

McCoy, B.J.; Smith, J.M.; Wang, M.; Zhang, C.J.

1993-02-01

The overall objective of this project was to study the supercritical fluid extraction of hydrocarbons from coal. Beyond the practical concern of deriving products from coal, the research has provided insights into the structure, properties, and reactivities of coal. Information on engineering fundamentals of coal thermolysis and extraction, including physical and chemical processes, is presented in this final report. To accomplish the goals of the project we developed continuous-flow experiments for fixed-bed samples of coal that allow two types of analysis of the extract: continuous spectrophotometric absorbance measurements of the lumped concentration of extract, and chromatographic determinations of molecular-weight distributions as a function of time. Thermolysis of coal yields a complex mixture of many extract products whose molecular-weight distribution (MWD) varies with time for continuous-flow, semibatch experiments. The flow reactor with a differential, fixed bed of coal particles contacted by supercritical t-butanol was employed to provide dynamic MWD data by means of HPLC gel permeation chromatography of the extract. The experimental results, time-dependent MWDs of extract molecules, were interpreted by a novel mathematical model based on continuous-mixture kinetics for thermal cleavage of chemical bonds in the coal network. The parameters for the MWDs of extractable groups in the coal and the rate constants for one- and two-fragment reaction are determined from the experimental data. The significant effect of temperature on the kinetics of the extraction was explained in terms of one- and two-fragment reactions in the coal.

Petrographic characteristics and depositional environment of Miocene Can coals, Canakkale-Turkey

Energy Technology Data Exchange (ETDEWEB)

Guerdal, Guelbin; Bozcu, Mustafa [Canakkale Onsekiz Mart University, Engineering and Architecture Faculty (Turkey)

2011-01-01

In this study, petrographic examinations along with proximate, calorific value, ultimate, sulphur form and XRD analyses were performed in order to determine the coal characteristics and the depositional environment of the Miocene Can coals. Seventy coal samples were taken from cores and open pit mines. The investigated Can coals are humic coals and classified as lignite to sub-bituminous coal based on the random huminite reflectance (0.38-0.54% R{sub r}), volatile matter (45.50-62.25 wt.%, daf) and calorific value (3419-6479 kcal/kg, maf). The sulphur content of the Can coals changes from 0.30 up to 12.23 wt.%, and a broad range of ash contents was observed varying between 2.46 wt.% and 41.19 wt.%. Huminite is the most abundant maceral group (74-95 vol.% mmf) consisting of mostly humocollinite (gelinite) which is followed by relatively low liptinite (2-18 vol.% mmf) and inertinite content (2-13 vol.% mmf). In general, major mineral contents of coal samples are clay minerals, quartz, mica, pyrite and feldspar. The Can-Etili lignite basin consists of mainly volcano-clastics, fluviatile and lacustrine clastic sediments and contains only one lignite seam with 17 m average thickness. In order to assess the development of paleo-mires, coal facies diagrams were obtained from maceral composition. According to the Vegetation Index (VI) and Ground Water Index (GWI), the Can coal accumulated in inundated marsh, limnic and swamp environments under a rheotrophic hydrological regime. In general, the facies interpretations are in accordance with the observed sedimentalogical data. (author)

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.

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.

Nuclear assay of coal. Volume 4. Moisture determination in coal: survey of electromagnetic techniques. Final report

International Nuclear Information System (INIS)

Bevan, R.; Luckie, P.; Gozani, T.; Brown, D.R.; Bozorgmanesh, H.; Elias, E.

1979-01-01

This survey consists of two basic parts. The first consists of a survey of various non-nuclear moisture determination techniques. Three techniques are identified as promising for eventual on-line application with coal; these are the capacitance, microwave attenuation, and nuclear magnetic resonance (NMR) techniques. The second part is devoted to an in-depth analysis of these three techniques and the current extent to which they have been applied to coal. With a given coal type, accuracies of +- 1% absolute in moisture content are achievable with all three techniques. The accuracy of the two electromagnetic techniques has been demonstrated in the laboratory and on-line in coal burning plants, whereas only small samples have been analyzed with NMR. The current shortcoming of the simple electromagnetic techniques is the sensitivity of calibrations to physical parameters and coal type. NMR is currently limited by small sample sizes and non-rugged design. These findings are summarized and a list of manufacturers of moisture analyzers is given in the Appendix

Nuclear assay of coal. Volume 7. Coal rheology and its impact on nuclear assay. Final report

International Nuclear Information System (INIS)

Hogg, R.; Luckie, P.; Gozani, T.

1979-01-01

A number of possible techniques for introducing coal to a continuous on-line nuclear analysis of coal (CONAC) system have been evaluated, including flow methods and nonflow methods. A modified flat-belt feeder system was recommended. The success of such a coal-presentation technique would rely on proper entry to the feed hopper, shape of the withdrawal opening from the feed hopper, and a slow belt speed to minimize demixing

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

Directory of Open Access Journals (Sweden)

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.

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

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.

Evaluation of dense-phase ultrafine coal (DUC) as a fuel alternative for oil- and gas-designed boilers and heaters. Final report

Energy Technology Data Exchange (ETDEWEB)

1986-12-01

Utility and industrial firms currently using oil- and gas-fired boilers have an interest in substitution of coal for oil and gas as the primary boiler fuel. This interest stems from coal`s two main advantages over oil and gas-lower cost and security of supply. Recent efforts in the area of coal conversion have been directed to converting oil- and gas- fired boilers which were originally designed for coal-firing or were designed with some coal-firing capability. Boilers designed exclusively for oil- or gas-firing have not been considered viable candidates for coal conversion because they generally require a significant capacity derating and extensive and costly modifications. As a result, conversion of boilers in this class to coal-firing has generally been considered unattractive. Renewed interest in the prospects for converting boilers designed exclusively for oil- and gas-firing to coal firing has centered around the concept of using ``ultra fine`` coal as opposed to ``conventional grind`` pulverized coal. The main distinction being the finer particle size to which the former is ground. This fuel type may have characteristics which ameliorate many of the boiler problems normally associated with pulverized coal-firing. The overall concept for ultrafine coal utilization is based on a regional large preparation plant with distribution of a ready to fire fuel directly to many small users. This differs from normal practice in which final coal sizing is performed in pulverizers at the user`s site.

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.

Permeability changes in coal resulting from gas desorption. Final report

Energy Technology Data Exchange (ETDEWEB)

Levine, J.R.; Johnson, P.W.

1992-11-30

This report documents studies on the effects of gas sorption on coal, with the intent of eventually evaluating how sorption and strain affect permeability. These studies were, carried out at the University of Alabama during the period from 1989 through 1992. Two major experimental methods were developed and used. In the strain experiments, electronic strain gauges were attached to polished blocks of coal in order to measure linear and volumetric swelling due to gas sorption. The effects of bedding plane orientation, of gas type, and of coal type were investigated. In the gravimetric experiment the weight of small samples of coal was measured during exposure to high pressure gases. Sample measurements were corrected for buoyancy effects and for sample swelling, and the results were plotted in the form of Langmuir isotherms. Experiments were conducted to determine the effect of grain size, coal type, moisture, and of sorbant gas. The advantage of this method is that it can be applied to very small samples, and it enabled comparison liptinite versus vitrinite concentrates, and kerogen rich versus kerogen depleted oil shales. Also included is a detailed discussion of the makeup of coal and its effect on gas sorption behavior.

Influence of the Interaction between Sphalerite and Pyrite on the Copper Activation of Sphalerite

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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.

Nuclear assay of coal. Volume 8. Continuous nuclear assay of coal (CONAC). Final report

International Nuclear Information System (INIS)

Lagarias, J.; Irminger, P.; Dodson, W.

1979-01-01

Using californium-252 as a source of exciting neutrons, prompt gamma photons emitted by elemental nuclei in the coal have been measured using several detectors, including sodium-iodide and germanium-lithium. Several coal types, including bituminous, subbituminous lignite and anthracite were crushed to various top sizes and analyzed carefully by traditional ASTM wet chemistry techniques at two or three different laboratories. The elements (sulfur, hydrogen, carbon, aluminum, silicon, iron, calcium, sodium, nitrogen, and chlorine) were determined by prompt neutron activations and the quantities compared with those of the wet chemical analyses. Since satisfactory correlation has been obtained at bench-scale level using 100 to 200 kG samples, an apparatus has been designed to analyze a coal stream of up to 50 ton/hour, at an electric power generating station

STUDY OF SOLVENT AND CATALYST INTERACTIONS IN DIRECT COAL LIQUEFACTION; FINAL

International Nuclear Information System (INIS)

Michael T. Klein; William H. Calkins; Jasna Tomic

2000-01-01

To provide a better understanding of the roles of a solid catalyst and the solvent in Direct Coal Liquefaction, a small reactor was equipped with a porous-walled basket which was permeable to the solvent but was not permeable to the coal or solid catalyst. With this equipment and a high volatile bituminous coal it was found that direct contact between the catalyst in the basket and the coal outside the basket is not required for catalyzed coal liquefaction. The character of the solvent in this system makes a significant difference in the conversion of the coal, the better solvents being strong donor solvents. Because of the extensive use of thermogravimetric analysis in this laboratory, it was noted that the peak temperature for volatiles evolution from coal was a reliable measure of coal rank. Because of this observation, a variety of coals of a range of ranks was investigated. It was shown in this work that measuring the peak temperature for volatiles evolution was a quite precise indicator of rank and correlated closely with the rank value obtained by measuring vitrinite reflectance, a more difficult measurement to make. This prompted the desire to know the composition of the volatile material evolved as a function of coal rank. This was then measured by coupling a TGA to a mass spectrometer using laser activation and photoionization detection TG-PI-MS. The predominant species in volatiles of low rank coal turned out to be phenols with some alkenes. As the rank increases, the relative amounts of alkene and aromatic hydrocarbons increases and the oxygenated species decrease. It was shown that these volatiles were actually pyrolytic products and not volatilization products of the coal. Solvent extraction experiments coupled with Thermogravimetric-photoionization-mass spectrometry (TG-PI-MS) indicated that the low boiling and more extractable material are essentially similar in chemical types to the non-extractable portions but apparently higher molecular weight

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,

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

Australian black coal statistics 1991

Energy Technology Data Exchange (ETDEWEB)

1992-01-01

This third edition of Australian black coal statistics covers anthracite, bituminous and subbituminous coals. It includes maps and figures on resources and coal fields and statistics (mainly based on the calendar year 1991) on coal demand and supply, production, employment and productivity in Australian coal mines, exports, prices and ports, and domestic consumption. A listing of coal producers by state is included. A final section presents key statistics on international world trade in 1991. 54 tabs.

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.

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

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.

Mineralization and trace element distribution in pyrite using EMPA in exploration drill holes from Cheshmeh Zard gold district, Khorasan Razavi Province, Iran

Directory of Open Access Journals (Sweden)

Zahra Alaminia

2015-10-01

-bearing pyrite stage with sericite, chalcedony and quartz. The pyrite isframboidal.. 4. Finally, a carbonate-dominated stage. The pyrite is euhedral to anhedral and coarse grained. The Au concentration in Stages 2 and 3 pyrite is higher than that in Stage 4 pyrite. Conclusions The gangue mineral assemblages of carbonate, chlorite, quartz, and minor sericite and potassium feldspar in the ore-forming process of the CheshmehZard gold district suggest that the pH value of the hydrothermal fluids was near neutral to slightly acid (approximately 4.5 to 5.3 under 250 to 300 °C and 1 kbar conditions and that gold would be transported mainly as Au(HS2- (Stefansson and Seward, 2004. Three types of pyrite based on the chemical composition have been investigated: As- bearing pyrite, Ti-V - bearing pyrite and pure or barren pyrite. EMPA analyses of the pyrite in gold veins show maximum concentrations of As (3.62 wt.%, Ti (3.91 wt.% and V (0.53 wt.% respectively. The occurrence of the gold is usually associated with arsenian pyrite and Ti-V - bearing pyrite. Veinlets of the Py1 coexisting with arseno-pyrite and gold Py2 implies the substitution of sulfur by arsenic. Gold precipitated under relatively reducing conditions in framboidal pyrite. Py3 formed prior to barren pyrite (IV. References Alaminia, Z., Karimpour, M.H., Homam, S.M. and Finger, F., 2013a. The magmatic record in the Arghash region, NE Iran, and tectonic implications. International Journal of Earth Sciences, 102(6:1603-1625. Ashrafpour, E., Ansdell, K.M. and Alirezaei, S., 2012. Hydrothermal fluid evolution and ore genesis in the Arghash epithermal gold prospect, northeastern Iran. Journal of Asian Earth Sciences, 51(1:30–44. Butler, I.B. and Rickard, D., 2000. Framboidal pyrite formation via the oxidation of iron (II monosulfide by hydrogen sulphide. Geochimica et Cosmochimica Acta, 64(15: 2665–2672. Samadi, M., 2001. Exploration in Arghash Gold Prospect. Geological Survey of Iran, unpublished report, Tehran, 73 pp. (in

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

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,

Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction. Final report

Energy Technology Data Exchange (ETDEWEB)

Chunshan Song; Schobert, H.H.; Parfitt, D.P. [and others

1997-11-01

Development of new catalysts is a promising approach to more efficient coal liquefaction. It has been recognized that dispersed catalysts are superior to supported catalysts for primary liquefaction of coals, because the control of initial coal dissolution or depolymerization requires intimate contact between the catalyst and coal. This research is a fundamental and exploratory study on catalytic coal liquefaction, with the emphasis on exploring novel bimetallic dispersed catalysts for coal liquefaction and the effectiveness of temperature-programmed liquefaction using dispersed catalysts. The primary objective of this research was to explore novel bimetallic dispersed catalysts from organometallic molecular precursors, that could be used in low concentrations but exhibit relatively high activity for efficient hydroliquefaction of coals under temperature-programmed conditions. We have synthesized and tested various catalyst precursors in liquefaction of subbituminous and bituminous coals and in model compound studies to examine how do the composition and structure of the catalytic precursors affect their effectiveness for coal liquefaction under different reaction conditions, and how do these factors affect their catalytic functions for hydrogenation of polyaromatic hydrocarbons, for cleavage of C-C bonds in polycyclic systems such as 4-(1-naphthylmethyl)bibenzyl, for hydrogenolysis of C-O bond such as that in dinaphthylether, for hydrodeoxygenation of phenolic compounds and other oxygen-containing compounds such as xanthene, and for hydrodesulfurization of polycyclic sulfur compounds such as dibenzothiophene. The novel bimetallic and monometallic precursors synthesized and tested in this project include various Mo- and Fe-based compounds.

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.

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

Mineral distribution in two southwest colombian coals using cyclone separation and oxidation at low temperature

International Nuclear Information System (INIS)

Rojas Andres F; Barraza, Juan M; Rojas, Andres F.

2010-01-01

It was studied the mineral distribution of two Colombian coals using a cyclone separation and oxidation at low temperature, OLT. The cyclone separation was carried out at two densities (1.3 and 1.4), three particle size (1000+ 600?m, 600+ 425?m and 425+ 250?m) and two processing stages. To determine the mineral matter, feed and under flow fractions from hydrocyclone were concentrated in mineral matter by OLT in a fluidized bed (T<300 celsius degrade). 18 minerals were identified by X Ray Diffraction, XRD. XRD results showed 13 minerals from Golondrinas and 15 minerals from Guachinte coal. It was found that kaolinite and quartz were the most abundant minerals in coal fractions from Golondrinas and Guachinte. Furthermore, it was found that mainly minerals kaolinite, quartz, dolomite, jarosite, gypsum and pyrite, exhibited affinity towards mineral matter, while siderite and valerite showed affinity towards organic matter.

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.

Wabash River Coal Gasification Repowering Project: A DOE Assessment; FINAL

International Nuclear Information System (INIS)

National Energy Technology Laboratory

2002-01-01

The goal of the U.S. Department of Energy (DOE) Clean Coal Technology Program (CCT) is to furnish the energy marketplace with a number of advanced, more efficient, and environmentally responsible coal utilization technologies through demonstration projects. These projects seek to establish the commercial feasibility of the most promising advanced coal technologies that have developed beyond the proof-of-concept stage. This document serves as a DOE post-project assessment (PPA) of a project selected in CCT Round IV, the Wabash River Coal Gasification Repowering (WRCGR) Project, as described in a Report to Congress (U.S. Department of Energy 1992). Repowering consists of replacing an existing coal-fired boiler with one or more clean coal technologies to achieve significantly improved environmental performance. The desire to demonstrate utility repowering with a two-stage, pressurized, oxygen-blown, entrained-flow, integrated gasification combined-cycle (IGCC) system prompted Destec Energy, Inc., and PSI Energy, Inc., to form a joint venture and submit a proposal for this project. In July 1992, the Wabash River Coal Gasification Repowering Project Joint Venture (WRCGRPJV, the Participant) entered into a cooperative agreement with DOE to conduct this project. The project was sited at PSI Energy's Wabash River Generating Station, located in West Terre Haute, Indiana. The purpose of this CCT project was to demonstrate IGCC repowering using a Destec gasifier and to assess long-term reliability, availability, and maintainability of the system at a fully commercial scale. DOE provided 50 percent of the total project funding (for capital and operating costs during the demonstration period) of$438 million

Temperature effects on chemical structure and motion in coal. Final report

Energy Technology Data Exchange (ETDEWEB)

Maciel, G.E.

1996-09-30

The objective of this project was to apply recently developed, state-of-the-art nuclear magnetic resonance (NMR) techniques to examine in situ changes in the chemical structure and molecular/macromolecular motion in coal as the temperature is increased above room temperature. Although alterations in the chemical structure of coal have been studied previously by {sup 13}C NMR, using quenched samples, the goal of this project was to examine these chemical structural changes, and changes in molecular/macromolecular mobility that may precede or accompany the chemical changes, at elevated temperatures, using modern {sup 13}C and {sup 1}H NMR techniques, especially {sup 1}H dipolar-dephasing techniques and related experiments pioneered in the laboratory for examining pyridine-saturated coals. This project consisted of the following four primary segments and related efforts on matters relevant to the first four tasks. (1) {sup 1}H NMR characterization of coal structure and mobility as a function of temperature variation over a temperature range (30--240 C) for which substantial chemical transformations were not anticipated. (2) {sup 1}H NMR characterization of coal structure, mobility and conversion as a function of temperature variation over a temperature range (240--500 C) for which chemical transformations of coal are known to occur. (3) {sup 13}C NMR investigation of coal structure/mobility as a function of temperature over a temperature range (30--240 C) for which substantial chemical transformations were not anticipated. (4) {sup 13}C NMR investigation of coal structure, dynamics and conversion as a function of temperature variation over a range (240--500 C) for which chemical transformations of coal are known to occur. (5) Related matters relevant to the first four tasks: (a) {sup 1}H CRAMPS NMR characterization of oil shales and their kerogen concentrates; and (b) improved quantitation in {sup 13}C MAS characterization of coals.

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

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.

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.

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.

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

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 ...

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.

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.

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.

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

The ENCOAL Mild Coal Gasification Project, A DOE Assessment; FINAL

International Nuclear Information System (INIS)

National Energy Technology Laboratory

2002-01-01

This report is a post-project assessment of the ENCOAL(reg s ign) Mild Coal Gasification Project, which was selected under Round III of the U.S. Department of Energy (DOE) Clean Coal Technology (CCT) Demonstration Program. The CCT Demonstration Program is a government and industry cofunded technology development effort to demonstrate a new generation of innovative coal utilization processes in a series of commercial-scale facilities. The ENCOAL(reg s ign) Corporation, a wholly-owned subsidiary of Bluegrass Coal Development Company (formerly SMC Mining Company), which is a subsidiary of Ziegler Coal Holding Company, submitted an application to the DOE in August 1989, soliciting joint funding of the project in the third round of the CCT Program. The project was selected by DOE in December 1989, and the Cooperative Agreement (CA) was approved in September 1990. Construction, commissioning, and start-up of the ENCOAL(reg s ign) mild coal gasification facility was completed in June 1992. In October 1994, ENCOAL(reg s ign) was granted a two-year extension of the CA with the DOE, that carried through to September 17, 1996. ENCOAL(reg s ign) was then granted a six-month, no-cost extension through March 17, 1997. Overall, DOE provided 50 percent of the total project cost of$90,664,000. ENCOAL(reg s ign) operated the 1,000-ton-per-day mild gasification demonstration plant at Triton Coal Company's Buckskin Mine near Gillette, Wyoming, for over four years. The process, using Liquids From Coal (LFC(trademark)) technology originally developed by SMC Mining Company and SGI International, utilizes low-sulfur Powder River Basin (PRB) coal to produce two new fuels, Process-Derived Fuel (PDF(trademark)) and Coal-Derived Liquids (CDL(trademark)). The products, as alternative fuel sources, are capable of significantly lowering current sulfur emissions at industrial and utility boiler sites throughout the nation thus reducing pollutants causing acid rain. In support of this overall

New coal-based energy systems

International Nuclear Information System (INIS)

Barnert, H.

1986-01-01

Conversion of coal into liquid fuels or into coal gas is considered and the use of high temperature nuclear reactors whose waste heat can be used for remote (district) heating mentioned. The use of high temperature reactors as energy source for coal gasification is also examined and, finally, the extraction of heat from combined coal, steel and high temperature nuclear reactors is suggested. (G.M.E.)

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.

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.

Characterization and suitability of superclean coals for hydroliquefaction feedstocks: Final report

Energy Technology Data Exchange (ETDEWEB)

Kim, Nam

1989-05-30

Superclean coals have been studied for their suitability as liquefaction feedstocks. The effects of ash and sulfur contents and two catalysts on a hydrogen donor solvent liquefaction reaction have been studied. Experiments were run using a unique coal of small particle size (90% <22 microns). The coal was characterized in terms of its chemical and its physical properties. This information made it possible to determine the effects of the static tube flotation separation on the coal. Once characterized the coals were liquefied in the hydrogen donor tetralin under a hydrogen atmosphere of 500 psig. The first series of experiments was to determine the effects of the ash on the liquefaction reaction. The second group of experiments dealt with the effects of catalysts (ammonium molybdate and titanium carbide) on low ash coals at various conditions. A model for batch liquefaction in a hydrogen donor solvent is then developed. This model is based on the assumption that the reaction is due to two competing mechanisms; (1) a thermal decomposition of the coal and (2) a catalytic reaction. The thermal reaction produces unwanted products while the catalytic reaction produces the desired products. To accurately model the batch system, mass transfer is considered. 51 refs., 50 figs., 29 tabs.

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)

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...

Influence of coal mine tips on the chalk aquifer. Sampling methods for three dimensional sulphate infiltration study

Energy Technology Data Exchange (ETDEWEB)

Barrez, F.; Mania, J. [Polytech' Lille, Dept. Genie Civil, UMR CNRS 8107 (LML), 59 - Villeneuve d' Ascq (France); Mansy, J.L. [Lille-1 Univ., Lab. de Sedimentologie et de Geodynamique, UMR CNRS 8110 (PBDS), 59 - Villeneuve d' Ascq (France); Piwakowski, B. [Ecole Centrale de Lille, Groupe Electronique Acoustique IEMN-DOAE, UMR CNRS 8520, 59 - Villeneuve d' Ascq (France)

2005-07-01

The coal basin of the Nord-Pas-de-Calais region (France) shows a very strong deterioration of the Chalk aquifer quality. In order to better model the hydro-dynamism and to improve knowledge on the chemical interactions, sampling according to depth of the groundwater is undertaken. The low-flow sampling and the profiles of the in-situ physicochemical parameters allow the observation of various vertical heterogeneities of the aquifer. The areas where the coal mine tips are localised appear very interesting to study. The sulphates released by the pyrite oxidation allow a 'artificial tracing' and give a visualization of the flow as well as information on the implied chemical processes between the oxidizing and reducing zones. (authors)

Influence of coal mine tips on the chalk aquifer. Sampling methods for three dimensional sulphate infiltration study

International Nuclear Information System (INIS)

Barrez, F.; Mania, J.; Mansy, J.L.; Piwakowski, B.

2005-01-01

The coal basin of the Nord-Pas-de-Calais region (France) shows a very strong deterioration of the Chalk aquifer quality. In order to better model the hydro-dynamism and to improve knowledge on the chemical interactions, sampling according to depth of the groundwater is undertaken. The low-flow sampling and the profiles of the in-situ physicochemical parameters allow the observation of various vertical heterogeneities of the aquifer. The areas where the coal mine tips are localised appear very interesting to study. The sulphates released by the pyrite oxidation allow a 'artificial tracing' and give a visualization of the flow as well as information on the implied chemical processes between the oxidizing and reducing zones. (authors)

Mineralogical and Geochemical Characteristics of Late Permian Coals from the Mahe Mine, Zhaotong Coalfield, Northeastern Yunnan, China

Directory of Open Access Journals (Sweden)

Xibo Wang

2015-07-01

Full Text Available This paper reports the mineralogical and geochemical compositions of the Late Permian C2, C5a, C5b, C6a, and C6b semianthracite coals from the Mahe mine, northeastern Yunnan, China. Minerals in the coals are mainly made up of quartz, chamosite, kaolinite, mixed-layer illite/smectite (I/S, pyrite, and calcite; followed by anatase, dolomite, siderite, illite and marcasite. Similar to the Late Permian coals from eastern Yunnan, the authigenic quartz and chamosite were precipitated from the weathering solution of Emeishan basalt, while kaolinite and mixed-layer I/S occurring as lenses or thin beds were related to the weathering residual detrital of Emeishan basalt. However, the euhedral quartz and apatite particles in the Mahe coals were attributed to silicic-rock detrital input. It further indicates that there has been silicic igneous eruption in the northeastern Yunnan. Due to the silicic rock detrital input, the Eu/Eu* value of the Mahe coals is lower than that of the Late Permian coals from eastern Yunnan, where the detrital particles were mainly derived from the basalt. The high contents of Sc, V, Cr, Co, Ni, Cu, Ga, and Sn in the Mahe coals were mainly derived from the Kangdian Upland.

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.

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

Coal-fired high performance power generating system. Final report

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-08-31

As a result of the investigations carried out during Phase 1 of the Engineering Development of Coal-Fired High-Performance Power Generation Systems (Combustion 2000), the UTRC-led Combustion 2000 Team is recommending the development of an advanced high performance power generation system (HIPPS) whose high efficiency and minimal pollutant emissions will enable the US to use its abundant coal resources to satisfy current and future demand for electric power. The high efficiency of the power plant, which is the key to minimizing the environmental impact of coal, can only be achieved using a modern gas turbine system. Minimization of emissions can be achieved by combustor design, and advanced air pollution control devices. The commercial plant design described herein is a combined cycle using either a frame-type gas turbine or an intercooled aeroderivative with clean air as the working fluid. The air is heated by a coal-fired high temperature advanced furnace (HITAF). The best performance from the cycle is achieved by using a modern aeroderivative gas turbine, such as the intercooled FT4000. A simplified schematic is shown. In the UTRC HIPPS, the conversion efficiency for the heavy frame gas turbine version will be 47.4% (HHV) compared to the approximately 35% that is achieved in conventional coal-fired plants. This cycle is based on a gas turbine operating at turbine inlet temperatures approaching 2,500 F. Using an aeroderivative type gas turbine, efficiencies of over 49% could be realized in advanced cycle configuration (Humid Air Turbine, or HAT). Performance of these power plants is given in a table.

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

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.

Identification and quantification of radionuclides in coal ash. Final report

International Nuclear Information System (INIS)

Alleman, J.E.; Clikeman, F.M.; Skronski, T.

1998-01-01

One of the important environmental issues raised recently in regard to coal ash reuse for highway construction purposes (e.g., embankment development) is that of worker, and public, exposure to radiation which might possibly be emitted by these types of residues. This research project subsequently addressed the associated issue of radiation emission by coal ash residuals generated within the State of Indiana, covering both fly ash and bottom ash materials. Samples were obtained at sixteen different coal-fired power generating facilities within Indiana and subjected to quantitative analysis of their associated gamma-ray emission levels. After identifying the responsible radionuclides, a conservative approximation was then developed for the worst-case potential occupational exposure with construction employees working on this type of high-volume, coal ash embankment. In turn, these potential emissions levels were compared to those of other traditional construction materials and other common sources

Temporal geochemical variations in above- and below-drainage coal mine discharge

Science.gov (United States)

Burrows, Jill E.; Peters, Stephen C.; Cravotta,, Charles A.

2015-01-01

Water quality data collected in 2012 for 10 above- and 14 below-drainage coal mine discharges (CMDs), classified by mining or excavation method, in the anthracite region of Pennsylvania, USA, are compared with data for 1975, 1991, and 1999 to evaluate long-term (37 year) changes in pH, SO42−, and Fe concentrations related to geochemistry, hydrology, and natural attenuation processes. We hypothesized that CMD quality will improve over time because of diminishing quantities of unweathered pyrite, decreased access of O2 to the subsurface after mine closure, decreased rates of acid production, and relatively constant influx of alkalinity from groundwater. Discharges from shafts, slopes, and boreholes, which are vertical or steeply sloping excavations, are classified as below-drainage; these receive groundwater inputs with low dissolved O2, resulting in limited pyrite oxidation, dilution, and gradual improvement of CMD water quality. In contrast, discharges from drifts and tunnels, which are nearly horizontal excavations into hillsides, are classified as above-drainage; these would exhibit less improvement in water quality over time because the rock surfaces continue to be exposed to air, which facilitates sustained pyrite oxidation, acid production, and alkalinity consumption. Nonparametric Wilcoxon matched-pair signed rank tests between 1975 and 2012 samples indicate decreases in Fe and SO42− concentrations were highly significant (p water quality presented in this paper can help prioritize CMD remediation and facilitate selection and design of the most appropriate treatment systems.

Cleavage and crosslinking of polymeric coal structures during pyrolysis. Final report

Energy Technology Data Exchange (ETDEWEB)

McMillen, D.F.; Malhotra, R.

1992-02-01

The ultimate objective of this project was to develop a better understanding of volatiles production to help optimize the yield and character of condensable coproducts during coal pyrolysis or mild gasification. The specific objectives were to (1) Develop pyrolysis procedures that minimize secondary reactions; and (2) Develop coal pretreatments that current knowledge suggests will prorate bond scission or prevent retrograde reactions. Our approach was to study the pyrolysis of coals and tar-loaded coals by using several techniques that span a range of heating rates and pressures. Slow-heating pyrolyses were performed at low pressures in the inlet of a field ionization mass spectrometer and at atmospheric pressures in a thermogravimetric analyzer. Moderately rapid-heating pyrolyses were performed in a vacuum TGA apparatus and in sealed silica ampules heated in a molten-salt bath. The fastest heating rates were achieved with laser pyrolysis at about 30,000 X/s. The high tar yield seen in this work where the entire volume of the coal particle becomes hot and fluid at very nearly the same time, taken together with the evident non-vapor transport of the tar under these conditions, emphasizes the importance of better understanding the development of fluidity during coal heating. This specifically includes the profound effects--long-recognized but poorly understood that mild oxidation has in suppressing coal fluidity. It also includes the more recently recognized fact that heating in the presence of an inert gas produced substantially greater fluidity than does heating in the presence of combustion gases, even if the conditions are very fuel rich and all the oxygen itself has already been consumed when the coal particles are encountered.

Too Much Coal, Too Little Oil

OpenAIRE

Frederick van der Ploeg; Cees Withagen

2011-01-01

Optimal climate policy is studied. Coal, the abundant resource, contributes more CO2 per unit of energy than the exhaustible resource, oil. We characterize the optimal sequencing oil and coal and departures from the Herfindahl rule. "Preference reversal" can take place. If coal is very dirty compared to oil, there is no simultaneous use. Else, the optimal outcome starts with oil, before using oil and coal together, and finally coal on its own, The "laissez-faire" outcome uses coal forever or ...

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....

Sulfur amino acids and alanine on pyrite (100) by X-ray photoemission spectroscopy: Surface or molecular role?

Science.gov (United States)

Sanchez-Arenillas, M.; Galvez-Martinez, S.; Mateo-Marti, E.

2017-08-01

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 NH2 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 NH3+ adsorption due to the sulfur vacancies in the pyrite being replaced by sulfur atom dimers (S22-) on the surface. Furthermore, even if the surface chemistry (monosulfide or disulfide species enrichment) is the main factor promoting a partial conversion from NH2 to NH3+ species, the unique chemical structure of each amino acid provides a particular fingerprint in the process.

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.

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.

Production development and utilization of Zimmer Station wet FGD by-products. Final report. Volume 4, A laboratory study conducted in fulfillment of Phase 2, Objective 1 titled. Inhibition of acid production in coal refuse amended with calcium sulfite and calcium sulfate - containing FGD solids

Energy Technology Data Exchange (ETDEWEB)

Hao, Y. L. [Ohio State Univ., Wooster, OH (United States); Dick, W. A. [Ohio State Univ., Wooster, OH (United States); Stehouwer, R. C. [Ohio State Univ., Wooster, OH (United States); Bigham, J. M. [Ohio State Univ., Wooster, OH (United States)

1998-06-30

Control of S0₂ emission from coal combustion requires desulfurization of coal before its combustion to produce coal refuse. Alternatively, gaseous emissions from coal combustion may be scrubbed to yield flue gas desulfurization (FGD) by-products that include calcium sulfite (CaSO₃∙0.5H₂O or simply CaS0₃). Acid production in coal refuse due to pyrite oxidation and disposal of large amounts of FGD can cause environmental degradation. Addition of CaS0₃ and CaS0₃-containing FGD to coal refuse may reduce the amounts of oxygen and ferric ion available to oxidize pyrite because the sulfite moiety in CaS0₃ is a strong reductant and thus may mitigate acid production in coal refuse. In Chapter 1, it was shown that CaS0₃ efficiently scavenged dissolved oxygen and ferric ion in water under the conditions commonly encountered in a coal refuse disposal environment. In the presence ofCaS0₃, the concentration of dissolved oxygen in water exposed to the atmosphere declined to below 0.01 mg L"1 at pH <8.0. In Chapter 2, it was demonstrated that CaS0₃ prevented a pH drop in coal refuse slurry when 0.2 gCaS0₃ was added to a 2% fresh coal refuse slurry every three days. Calcium sulfite also inhibited acid leaching from fresh coal refuse in bench-scale columns under controlled conditions. During the initial 13 weeks of leaching, the total amounts of titratable acidity, soluble H\\ Fe, and Al from CaS0₃-treated refuse (6.4 gin 50 g fresh coal refuse) were only 26%,10%, 32%, and 39% of those of the control columns, respectively. A combination of CaS0₃ with CaC0₃ or fly ash enhanced the inhibitory effect of CaS0₃ on acid leaching. Calcium sulfite-containing FGD which combined CaS0₃, CaC0₃, fly ash, and gypsum showed a much stronger inhibitory effect on acid leaching than CaS0₃ alone. This

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.

Evaluation, engineering and development of advanced cyclone processes

Energy Technology Data Exchange (ETDEWEB)

Durney, T.E.; Cook, A. [Coal Technology Corporation, Bristol, VA (United States); Ferris, D.D. [ICF Kaiser Engineers, Inc., Pittsburgh, PA (United States)] [and others

1995-11-01

This research and development project is one of three seeking to develop advanced, cost-effective, coal cleaning processes to help industry comply with 1990 Clean Air Act Regulations. The specific goal for this project is to develop a cycloning technology that will beneficiate coal to a level approaching 85% pyritic sulfur rejection while retaining 85% of the parent coal`s heating value. A clean coal ash content of less than 6% and a moisture content, for both clean coal and reject, of less than 30% are targeted. The process under development is a physical, gravimetric-based cleaning system that removes ash bearing mineral matter and pyritic sulfur. Since a large portion of the Nation`s coal reserves contain significant amounts of pyrite, physical beneficiation is viewed as a potential near-term, cost effective means of producing an environmentally acceptable fuel.

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

Precombustion desulfurization using Microcel{trademark} and multi-gravity separator

Energy Technology Data Exchange (ETDEWEB)

Yoon, R.H.; Luttrell, G.H.; Venkatraman, P. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)

1994-12-31

Studies conducted at the Center for Coal and Minerals Processing (CCMP) indicate that surface-based processes such as froth flotation are inefficient in removing pyrite from fine coal. This shortcoming has been attributed to the fact that pyrite can become hydrophobic under certain conditions and to the inability of flotation to reject middling particles. To overcome these deficiencies, a new processing scheme has been developed at CCMP which involved the use of the Microcel{trademark} flotation column in combination with a centrifugal flowing-film separator, called a Multi-Gravity Separator (MGS). The flotation column removes ash-forming minerals such as clay, while the MGS is effective in removing pyrite. Preliminary test data obtained with high-sulfur coals shows that this processing scheme can nearly double the pyritic sulfur rejection with little loss in clean coal yield. This article discusses the underlying principles of the new circuit and provides test results obtained using eastern U.S. coals.

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.

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.

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.

Depositional setting, petrology and chemistry of Permian coals from the Parana Basin: 2. South Santa Catarina Coalfield, Brazil

Energy Technology Data Exchange (ETDEWEB)

Kalkreuth, W.; Mexias, A.; Balbinot, M.; Levandowski, J. [Instituto de Geociencias, UFRGS, Porto Alegre (Brazil); Holz, M. [Inst. de Geociencias, UFBA, Salvador, Bahia (Brazil); Willett, J.; Finkelman, R. [U.S. Geological Survey, Reston, VA (United States); Burger, H. [Freie Universitaet Berlin, Geoinformatik, (Germany)

2010-12-01

In Brazil economically important coal deposits occur in the southern part of the Parana Basin, where coal seams occur in the Permian Rio Bonito Formation, with major coal development in the states of Rio Grande de Sul and Santa Catarina. The current paper presents results on sequence stratigraphic interpretation of the coal-bearing strata, and petrological and geochemical coal seam characterization from the South Santa Catarina Coalfield, Parana Basin. In terms of sequence stratigraphic interpretation the precursor mires of the Santa Catarina coal seams formed in an estuarine-barrier shoreface depositional environment, with major peat accumulation in a high stand systems tract (Pre-Bonito and Bonito seams), a lowstand systems tract (Ponta Alta seam, seam A, seam B) and a transgressive systems tract (Irapua, Barro Branco and Treviso seams). Seam thicknesses range from 1.70 to 2.39 m, but high proportions of impure coal (coaly shale and shaley coal), carbonaceous shale and partings reduce the net coal thickness significantly. Coal lithoypes are variable, with banded coal predominant in the Barro Branco seam, and banded dull and dull coal predominantly in Bonito and Irapua seams, respectively. Results from petrographic analyses indicate a vitrinite reflectance range from 0.76 to 1.63 %Rrandom (HVB A to LVB coal). Maceral group distribution varies significantly, with the Barro Branco seam having the highest vitrinite content (mean 67.5 vol%), whereas the Irapua seam has the highest inertinite content (33.8 vol%). Liptinite mean values range from 7.8 vol% (Barro Branco seam) to 22.5 vol% (Irapua seam). Results from proximate analyses indicate for the three seams high ash yields (50.2 - 64.2 wt.%). Considering the International Classification of in-Seam Coals, all samples are in fact classified as carbonaceous rocks (> 50 wt.% ash). Sulfur contents range from 3.4 to 7.7 wt.%, of which the major part occurs as pyritic sulfur. Results of X-ray diffraction indicate the

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

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.

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.

Extractive de-sulfurization and de-ashing of high sulfur coals by oxidation with ionic liquids

International Nuclear Information System (INIS)

Saikia, Binoy K.; Khound, Kakoli; Baruah, Bimala P.

2014-01-01

Highlights: • Extractive de-sulfurization and de-ashing process for cleaning high sulfur coals. • The process removes inorganic as well as organic sulfur components from high sulfur coals. • The process has less risk to chemists and other surroundings. - Abstract: The environmental consequences of energy production from coals are well known, and are driving the development of desulfurization technologies. In this investigation, ionic liquids were examined for extractive desulfurization and de-ashing in industrially important high sulfur sub-bituminous Indian coals. The ionic liquids, namely, 1-n-butyl-3-methylimidazolium tetrafluoroborate (IL1) and 1-n-butyl 3-methylimidazolium chloride (IL2) were employed for desulfurization of a few Indian coal samples in presence of HCOOH/H 2 O 2 and V 2 O 5 . Results show the maximum removal of 50.20% of the total sulfur, 48.00% of the organic sulfur, and 70.37 wt% of the ash in this process. The ionic liquids were recovered and subsequently used for further desulfurization. FT-IR spectra reveal the transformation of organic sulfur functionalities into the sulfoxides (S=O) and sulfones (-SO 2 ) due to the oxidative reactions. The sulfate, pyrite and sulfides (aryls) signals in the near edge X-ray absorption fine structure (NEXAFS) of the oxidized coal samples showed sulfur transformation during the desulfurization process. The study demonstrates the removal of significant amount of inorganic as well as organic sulfur (aryls) components from the original high sulfur coal samples to make them cleaner

COFIRING BIOMASS WITH LIGNITE COAL; FINAL

International Nuclear Information System (INIS)

Darren D. Schmidt

2002-01-01

The University of North Dakota Energy and Environmental Research Center, in support of the U.S. Department of Energy's (DOE) biomass cofiring program, completed a Phase 1 feasibility study investigating aspects of cofiring lignite coal with biomass relative to utility-scale systems, specifically focusing on a small stoker system located at the North Dakota State Penitentiary (NDSP) in Bismarck, North Dakota. A complete biomass resource assessment was completed, the stoker was redesigned to accept biomass, fuel characterization and fireside modeling tests were performed, and an engineering economic analysis was completed. In general, municipal wood residue was found to be the most viable fuel choice, and the modeling showed that fireside problems would be minimal. Experimental ash deposits from firing 50% biomass were found to be weaker and more friable compared to baseline lignite coal. Experimental sulfur and NO(sub x) emissions were reduced by up to 46%. The direct costs savings to NDSP, from cogeneration and fuel saving, results in a 15- to 20-year payback on a$1,680,000 investment, while the total benefits to the greater community would include reduced landfill burden, alleviation of fees for disposal by local businesses, and additional jobs created both for the stoker system as well as from the savings spread throughout the community

Pyrite oxidation in the presence of hematite and alumina: I. Batch leaching experiments and kinetic modeling calculations.

Science.gov (United States)

Tabelin, Carlito Baltazar; Veerawattananun, Suchol; Ito, Mayumi; Hiroyoshi, Naoki; Igarashi, Toshifumi

2017-02-15

Pyrite is one of the most common and geochemically important sulfide minerals in nature because of its role in the redox recycling of iron (Fe). It is also the primary cause of acid mine drainage (AMD) that is considered as a serious and widespread problem facing the mining and mineral processing industries. In the environment, pyrite oxidation occurs in the presence of ubiquitous metal oxides, but the roles that they play in this process remain largely unknown. This study evaluates the effects of hematite (α-Fe 2 O 3 ) and alumina (α-Al 2 O 3 ) on pyrite oxidation by batch-reactor type experiments, surface-sensitive characterization of the oxidation layer and thermodynamic/kinetic modeling calculations. In the presence of hematite, dissolved sulfur (S) concentration dramatically decreased independent of the pH, and the formation of intermediate sulfoxy anionic species on the surface of pyrite was retarded. These results indicate that hematite minimized the overall extent of pyrite oxidation, but the kinetic model could not explain how this suppression occurred. In contrast, pyrite oxidation was enhanced in the alumina suspension as suggested by the higher dissolved S concentration and stronger infrared (IR) absorption bands of surface-bound oxidation products. Based on the kinetic model, alumina enhanced the oxidative dissolution of pyrite because of its strong acid buffering capacity, which increased the suspension pH. The higher pH values increased the oxidation of Fe 2+ to Fe 3+ by dissolved O 2 (DO) that enhanced the overall oxidative dissolution kinetics of pyrite. Copyright © 2016 Elsevier B.V. All rights reserved.

A preliminary study of mineralogy and geochemistry of four coal samples from northern Iran

Energy Technology Data Exchange (ETDEWEB)

Goodarzi, F.; Sanei, H.; Stasiuk, L.D.; Reyes, J. [Natural Resources Canada, Geological Survey of Canada-Calgary Division, Calgary, Alberta (Canada); Bagheri-Sadeghi, H. [Department of Chemistry, Faculty of Science, Azad University, Central Campus, Tehran (Iran)

2006-01-03

This study is related to four Jurassic-age bituminous coal (0.69-1.02 Ro%) samples collected from coal mines from the west, central and east of central, Alborz in northern Iran. Geological settings played key roles in determining the geochemistry and mineralogy of coals from the central Alborz region of northern Iran. The mineralogy of coals from the eastern part of the region is dominated by kaolinite; halloysite; and carbonates such as calcite, dolomite/ankerite, and siderite. The coals were deposited in a lacustrine environment. In the western part of the region, where the depositional setting was also lacustrine with volcanic input and tonstein deposition (glass shards present), the coal primarily contains kaolinite (68%) and fluorapatite (26%). In contrast, coal from the central part of the region, which was deposited in a terrestrial environment and on eroded limestone and dolomite rocks, is dominated by dolomite (98%) with little input by kaolinite. These coals have low sulphur (0.35-0.70 wt.%), which is mostly in the organic form (0.34-0.69 wt.%). Pyritic sulphur is detected only in one coal and in small quantities. The boron contents of these coals range from 9 to 33 mg/kg, indicating that deposition occurred in a fresh water environment. Coal with higher concentrations of Ba, Sr, and P contain fluorapatite and goyazite-gorceixite series [BaAl{sub 3} (PO{sub 4}){sub 2} (OH){sub 5}, H{sub 2}O] minerals, which indicates volcanoclastic input. Compared to world coal averages, these coals exhibit low concentrations of elements of environmental concern, such as As (1.3-5.9 mg/kg), Cd (<0.02-0.06 mg/kg), Hg (<0.01-0.07 mg/kg) Mo (<0.6-1.7 mg/kg), Pb (4.8-13 mg/kg), Th (0.5-21 mg/kg), Se (<0.2-0.8 mg/kg) and U (0.2-4.6 mg/kg). Two of the northern Iranian coals have concentrations of Cl (2560 and 3010 mg/kg) that are higher than world coal average. (author)

Cooperative research in coal liquefaction. Final report, May 1, 1990-- April 30, 1991

Energy Technology Data Exchange (ETDEWEB)

Huffman, G.P. [ed.

1992-02-15

The Consortium for Fossil Fuel Liquefaction Science (CFFLS) is currently engaged in a three year contract with the US Department of Energy investigating a range of research topics dealing with direct coal liquefaction. This report summarizes the results of this program in its second year, from May 1, 1990 to April 30, 1991. Accomplishments for this period are presented for the following tasks: Iron-based catalysts for coal liquefaction, exploratory research on coal conversion, novel coal liquefaction concepts, and novel catalysts for coal liquefaction.

Evaluation, engineering and development of advanced cyclone processes

International Nuclear Information System (INIS)

Durney, T.E.; Cook, A.; Ferris, D.D.

1995-01-01

This research and development project is one of three seeking to develop advanced, cost-effective, coal cleaning processes to help industry comply with 1990 Clean Air Act Regulations. The specific goal for this project is to develop a cycloning technology that will beneficiate coal to a level approaching 85% pyritic sulfur rejection while retaining 85% of the parent coal's heating value. A clean coal ash content of less than 6% and a moisture content, for both clean coal and reject, of less than 30% are targeted. The process under development is a physical, gravimetric-based cleaning system that removes ash bearing mineral matter and pyritic sulfur. Since a large portion of the Nation's coal reserves contain significant amounts of pyrite, physical beneficiation is viewed as a potential near-term, cost effective means of producing an environmentally acceptable fuel

Berau coal in East Kalimantan; Its petrographics characteristics and depositional environment

Directory of Open Access Journals (Sweden)

Nana Suwarna

2014-06-01

Full Text Available http://dx.doi.org/10.17014/ijog.vol2no4.20071To asses the characteristics of the Early to Middle Miocene Berau coal in the Berau Basin, leading to interpretation of coal depositional environments, some fresh outcrop and subcrop samples and also drill cores of the coals have been analyzed microscopically. Coal petrographic analysis was performed on twenty four coal samples from the Middle Miocene Lati Formation. Vitrinite, present in a high value, and ranging between 66.2 - 96.2%, is dominated by vitrinite B. On the other hand, inertinite and exinite, showing a similar value, exist in a low to moderate amount. Vitrinite reflectance, present in a low value, varies from 0.40 - 0.58%. Low mineral matter content is dominated by clay minerals (0.4 - 6.6% with minor pyrite. Transitions from wet and very wet forested swamps to drier conditions with lower tree density are indicated by the higher content of vitrinite B, whilst a reverse trend is indicated by the lower content of vitrinite A. Petrographic indices obtained from facies diagnostic macerals show that an accumulation of the ancient peats under prevailing relatively wet limited influx clastic marsh to very wet forest swamps or moors is considered. The composition of the coal samples supports the interpretation of a system of fluvial to meandering streams in an upper delta plain environment. The original peat-forming vegetation was composed mainly of cellulose rich, shrub-like plants, tree ferns, herbaceous plant communities, with minor amount of trees. Thereby, the organic facies concept is thus applicable in basin studies context and has potential to become an additional tool for depositional environment interpretation.  

Early diagenetic high-magnesium calcite and dolomite indicate that coal balls formed in marine or brackish water: Stratigraphic and paleoclimatic implications

Science.gov (United States)

Raymond, Anne

2016-04-01

Coal balls are carbonate and pyrite permineralizations of peat that contain three-dimensional plant fossils preserved at the cellular level. Coal balls, which occur in Pennsylvanian and earliest Permian equatorial coals, provide a detailed record of terrestrial ecology and tropical climate during the Late Paleozoic Ice Age; yet their depositional environment remains controversial. The exquisite preservation of some coal-ball fossils, e.g. pollen with pollen tubes and leaves with mesophyll, indicates rapid formation. The presence of abundant, cement-filled, void spaces within and between the plant debris in most coal balls indicates that they formed in uncompacted peat, near the surface of the mire. Botanical, taphonomic and isotopic evidence point to a freshwater origin for coal balls. The nearest living relatives of coal ball plants (modern lycopsids, sphenopsids, marratialean ferns and conifers) grow in fresh water. Coal-ball peat contains a high percentage of aerial debris, similar to modern freshwater peat. The stable oxygen isotopes of coal-ball carbonate (δ18O = 16 to 3 per mil) suggest a freshwater origin. However, the widespread occurrence of marine invertebrates and early diagenetic framboidal pyrite in coal balls suggests that many formed in close proximity to marine water. Indeed, carbonate petrology points to a marine or brackish water origin for the first-formed carbonate cements in coal balls. Petrographic and geochemical (microprobe) analysis of coal-ball carbonates in Pennsylvanian coals from the midcontinent of North America (Western Interior Basin, West Pangaea) and the Ruhr and Donets Basins (East Pangaea) indicate that the first formed carbonate is either radaxial, nonstochiometric dolomite or high magnesium calcite (9 - 17 mol % MgCO3, indicating precipitation in marine or brackish water. Although both primary dolomite and high magnesium calcite can form in lacustrine settings, the lakes in which these minerals form occur in carbonate terranes

Non-matrix corrected organic sulfur determination by energy dispersive X-ray spectroscopy for western Kentucky coals and residues

International Nuclear Information System (INIS)

Clark, C.P.; Freeman, G.B.; Hower, J.C.

1984-01-01

A method for non-matrix corrected organic sulfur analysis by energy dispersive X-ray spectroscopy has been developed using petroleum coke standards. Typically, electron beam microanalysis is a rapid, nondestructive analytical technique to quantitatively measure organic sulfur in coal. The results show good correlation to ASTM values for numerous well characterized coals with a wide range in total and pyritic sulfur content. This direct analysis is capable of reducing error commonly associated with the present ASTM method which relies on an indirect measure of organic sulfur by difference. The precision of the organic sulfur values determined in the present study is comparable to that obtained by ZAF matrix corrected microanalysis. The energy dispersive microanalysis is capable of measuring micro as well as bulk organic sulfur levels

Final report on dust monitoring near Kellingley coal mine, North Yorkshire

International Nuclear Information System (INIS)

Vallack, H.W.

1992-06-01

Dust deposition was monitored at a residential location near Kellingley Coal Mine over two four-weekly periods (November/December 1991 and March/April 1992) using a wet Frisbee dust deposit gauge. The mean rates of dust deposition for both periods (696.4 and 415.5 mg m -2 day -1 respectively) were well in excess of a proposed acceptable upper limit (195 mg m -2 day -1 ) for residential conditions. Mean estimated coal dust content during both periods (80.9 and 49.7 per cent) was also high. It is concluded that coal dust from Kellingley Coal Mine gave rise to excessively high levels of dust deposition at the monitoring site, especially during the first four-weekly period. The situation would appear to have deteriorated since a similar monitoring exercise was carried out in 1989. 4 refs, 2 figs, 2 tabs

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)

Coal in Europe: what future?: prospects of the coal industry and impacts study of the Kyoto Protocol

International Nuclear Information System (INIS)

Rudianto, E.

2006-12-01

From the industrial revolution to the 1960's, coal was massively consumed in Europe and its utilization was constantly raised. In the aftermath of World War II, coal had also an important part in reconstruction of Western Europe's economy. However, since the late 1960's, its demand has been declining. There is a (mis)conception from a number of policy makers that saying coal mining and utilizations in Europe is unnecessary. Therefore in the European Union (EU) Green Paper 2000, coal is described as an 'undesirable' fuel and the production of coal on the basis of economic criteria has no prospect. Furthermore, the commitment to the Kyoto Protocol in reducing greenhouse gases emission has aggravated this view. Faced with this situation, the quest for the future of coal industry (mining and utilization) in the lines of an energy policy is unavoidable. This dissertation did a profound inquiry trying to seek answers for several questions: Does the European Union still need coal? If coal is going to play a part in the EU, where should the EU get the coal from? What should be done to diminish negative environmental impacts of coal mining and utilization? and finally in regard to the CO 2 emission concerns, what will the state of the coal industry in the future in the EU? To enhance the analysis, a system dynamic model, called the Dynamics Coal for Europe (the DCE) was developed. The DCE is an Energy-Economy-Environment model. It synthesizes the perspectives of several disciplines, including geology, technology, economy and environment. It integrates several modules including exploration, production, pricing, demand, import and emission. Finally, the model emphasizes the impact of delays and feed-back in both the physical processes and the information and decision-making processes of the system. The calibration process for the DCE shows that the model reproduces past numbers on the scale well for several variables. Based on the results of this calibration process, it can

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...

Prevention of formation of acid drainage from high-sulfur coal refuse by inhibition of iron- and sulfur-oxidizing microorganisms. II. Inhibition in run of mine refuse under simulated field conditions

Energy Technology Data Exchange (ETDEWEB)

Dugan, P.R.

1987-01-01

The combination of sodium lauryl sulfate and benzoic acid effectively inhibits iron- and sulfur-oxidizing bacteria in coal refuse and prevents the conversion of iron pyrite to sulfate, ferric iron, and sulfuric acid, thereby significantly reducing the formation of acidic drainage from coal refuse. The inhibitors were effective in a concentration of 1.1. mg/kg refuse, and data indicate that the SLS was in excess of the concentration required. The treatment was compatible with the use of lime for neutralization of acid present prior to inhibition of its formation.

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 (water samples from sludge-treated spoil, frequently exceeding 10 mg/L. Downgradient decreases in nitrate to less than 3 mg/L and increases in sulfate concentrations in underlying ground water could result from 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.

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

Sequential solvent extraction for the modes of occurrence of selenium in coals of different ranks from the Huaibei Coalfield, China

Directory of Open Access Journals (Sweden)

Wang Lei

2007-12-01

Full Text Available Abstract Forms of selenium in bituminous coal, anthracite, and cokeite (natural coke from Huaibei Coalfield, Anhui, China, have been determined by sequential solvent extraction. The selenium content in bulk samples is 4.0, 2.4, and 2.0 μg/g in bituminous coal, anthracite, and cokeite, respectively. The six forms of selenium determined by six-step solvent extraction are water-leachable, ion-exchangeable, organic matter-associated, carbonate-associated, silicate-associated, and sulfide-associated. The predominant forms of selenium in bituminous coal are organic matter-associated (39.0%, sulfide-associated (21.1%, and silicate bound (31.8%; these three forms account for 92% of the total. The organic matter bound-selenium decrease dramatically from bituminous coal (39.0% to anthracite (11.6% and to cokeite (0%, indicating that organic matter bound selenium is converted to other forms during metamorphism of the coal, most likely sulfide-form. The sulfide-associated form increased remarkably from bituminous coal (21.1% to anthracite (50.4% and cokeite (54.5%, indicating the formation of selenium sulfide, possibly in pyrite during the transformation of bituminous coal to anthracite and cokeite. The silicate-associated selenium in bituminous coal (31.8% is much higher than that in anthracite (16.4% and cokeite (15.8%, indicating that silicate-associated selenium is partly converted to sulfide during metamorphism.

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

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

New improvements in the characterization of refractory gold in pyrites: an electron microprobe, Moessbauer spectrometry and ion microprobe study

International Nuclear Information System (INIS)

Marion, P.; Holliger, P.; Boiron, M.C.; Cathelineau, M.; Wagner, F.E.

1991-01-01

Studies of pyrites by Moessbauer spectroscopy have shown the presence of gold in a combined state probably inserted within the lattice. In order to enhance detection limits for in-situ quantitative gold analyses, new SIMS investigations have been made thanks to a Resistive Anode Encorder record of the ion emissions, which provides digital images or scans of any part of the analyzed volume. Quantitative analysis of gold have been carried out thanks to 2 MeV ion implantation of gold in reference sulfide crystals, and the bulk composition of a pyrite grain has been determined. Some strong enrichments in gold and arsenic at the crystal margin attest fluctuations in the fluid chemistry and may be interpreted as a final growth zone, which is similar to that observed on arsenopyrite crystals. This multidisciplinary approach constitutes a powerful tool for the investigation of the insertion and distribution of trace elements within crystals, especially gold in sulfides at low contents down to a few ppm. (author)

Chemostratigraphy and trace element pattern of authigenic pyrite in a Frasnian-Fammenian transition section (Büdesheimer bach, Germany)

Science.gov (United States)

Pujol, F.; Berner, Z.; Neumann, T.; Stüben, D.

2003-04-01

Trace element contents in authigenic pyrite were investigated in relationship to the geochemistry of host rocks in a 160 m deep drilling at Büdesheimer Bach (Prümer Mulde, Germany), in order to put constrains on possible changes in depositional conditions and seawater composition related to the Kellwasser events (Frasnian/Fammenian transition). The approach is based on the observation that the trace element pattern of authigenic pyrite is controlled by genetic conditions (Stüben et al., 2002) and that the content of elements with generally high degree of pyritization (DTMP, degree of trace metal pyritization, like As, Mo, Co, Ni, etc.) depends on their availability at the site of pyrite formation (e.g. Huerta-Diaz and Morse, 1992). The distribution of trace elements in the bulk rock essentially reflects mineralogical composition and redox conditions which are mainly controlled by the flux of organic matter entering the sediment. The lower and upper Kellwasser horizons are marked by an increase in carbonate and organic carbon content (up to 2%), coupled with an increase in the degree of pyritization of Fe (DOP: 0.4-0.8), indicating a change from normal marine to suboxic/anoxic conditions. A simultaneous drop in the Ba content of the host lithology, which usually is used as a proxy for paleoproductivity, can be explained by the removal of Ba dissolved in pore water under anoxic conditions (McManus et al., 1998). While low in the host rock, the Ba content of authigenic pyrite is high in these horizons, suggesting that pyrite may preserve the initial composition of pore water even for some elements with generally low DTMP, like Ba. Consequently, Ba content in pyrite may serve as indicator for productivity even when the Ba content of sediment can not be used due to its poor preservation. During these anoxic episodes also a significant increase in the content of As, U, V was registered in pyrite. Opposite to these, others like Ni, Co, Ag show a decrease in their

Dewatering of ultrafine coal: Final report, August 1984-December 1986

Energy Technology Data Exchange (ETDEWEB)

Chiang, Shiao-Hung; Klinzing, G.E.; Morsi, B.I.; Tierney, J.W.; Badgujar, M.; Binkley, T.; Cheng, Yisun; Huang, Suxuan; Qamar, I.; Venkatadri, R.

1986-12-01

The surfactant, Aerosol-OT, was used to wash distilled water cakes. In previous studies, cakes were washed with Triton X-114. The dewatering performance and influence on cake structure of the two reagents are compared. Also, filter cakes were analyzed using an image analysis system and micrographic analysis of coal particles was initiated. In the area of theoretical modelling, the concept of bond-flow correlation greatly improved the network model predicting the experimental desaturation curves. Predicted results for treated cakes suggested that the effect of the presence of surface-active agents was adequately accounted for. The effects of the various operating conditions on the filtration/dewatering characteristics of the 10 ..mu..m coal particles were assessed and comparisons with the -32 mesh coal were made as to its trends in response to changes in the operating conditions. 20 refs., 75 figs., 17 tabs.

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.

The environment, public relations and coal

Energy Technology Data Exchange (ETDEWEB)

Wood, W.J. (Coal Association of Canada, Calgary, AB (Canada))

1990-09-01

Information is presented in note format. The presentation covers world environmental issues such as the greenhouse effect, an overview of the coal industry's role in atmospheric emissions of CO{sub 2}, and finally, the need for the coal industry to make the public aware of coal's current and future role in our economic and energy future.

Effects of long-term coal supply contracts on technology adoption and improvements in the mining of coal. Final technical report

Energy Technology Data Exchange (ETDEWEB)

Walton, D.R.; Hawkins, S.A.; Webb, P.F.; Kauffman, P.W.

1979-08-01

The relationship between long-term coal supply contracts and the adoption of new technology in the coal mining industry is a complex one. From this study certain conclusions can be drawn. New technologies and improvements in the mining of coal can be logically categorized into three areas: evolutionary technology, transitional technology, or innovative technology. Evolutionary improvements in technology can be categorized as improvements, or increased production capacities, in existing equipment. Transitional technology involves the adoption of existing or proven technologies into new conditions, or, proceeding from one technology type to a newer type for the same function. Innovative technology includes equipment, concepts, and systems not readily available, or untried, in the existing mining environment (seam conditions, etc.). Technology adoption is an economic decision. This point was repeatedly emphasized by industry representatives contacted during the study. The long-term coal supply contract influences the decision to adopt new technology and mining improvements in several ways depending on the technology type (i.e., evolutionary, transitional, or innovative), and also the coal supplier type (i.e., captive or independent producer). Several examples of the adoption of new technologies in mines under long-term coal supply contracts are discussed. (LTN)

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.

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

A convenient method for the quantitative determination of elemental sulfur in coal by HPLC analysis of perchloroethylene extracts

Science.gov (United States)

Buchanan, D.H.; Coombs, K.J.; Murphy, P.M.; Chaven, C.

1993-01-01

A convenient method for the quantitative determination of elemental sulfur in coal is described. Elemental sulfur is extracted from the coal with hot perchloroethylene (PCE) (tetrachloroethene, C2Cl4) and quantitatively determined by HPLC analysis on a C18 reverse-phase column using UV detection. Calibration solutions were prepared from sublimed sulfur. Results of quantitative HPLC analyses agreed with those of a chemical/spectroscopic analysis. The HPLC method was found to be linear over the concentration range of 6 ?? 10-4 to 2 ?? 10-2 g/L. The lower detection limit was 4 ?? 10-4 g/L, which for a coal sample of 20 g is equivalent to 0.0006% by weight of coal. Since elemental sulfur is known to react slowly with hydrocarbons at the temperature of boiling PCE, standard solutions of sulfur in PCE were heated with coals from the Argonne Premium Coal Sample program. Pseudo-first-order uptake of sulfur by the coals was observed over several weeks of heating. For the Illinois No. 6 premium coal, the rate constant for sulfur uptake was 9.7 ?? 10-7 s-1, too small for retrograde reactions between solubilized sulfur and coal to cause a significant loss in elemental sulfur isolated during the analytical extraction. No elemental sulfur was produced when the following pure compounds were heated to reflux in PCE for up to 1 week: benzyl sulfide, octyl sulfide, thiane, thiophene, benzothiophene, dibenzothiophene, sulfuric acid, or ferrous sulfate. A sluury of mineral pyrite in PCE contained elemental sulfur which increased in concentration with heating time. ?? 1993 American Chemical Society.

Sulfur-oxidizing bacteria dominate the microbial diversity shift during the pyrite and low-grade pyrolusite bioleaching process.

Science.gov (United States)

Han, Yifan; Ma, Xiaomei; Zhao, Wei; Chang, Yunkang; Zhang, Xiaoxia; Wang, Xingbiao; Wang, Jingjing; Huang, Zhiyong

2013-10-01

The microbial ecology of the pyrite-pyrolusite bioleaching system and its interaction with ore has not been well-described. A 16S rRNA gene clone library was created to evaluate changes in the microbial community at different stages of the pyrite-pyrolusite bioleaching process in a shaken flask. The results revealed that the bacterial community was disturbed after 5 days of the reaction. Phylogenetic analysis of 16S rRNA sequences demonstrated that the predominant microorganisms were members of a genus of sulfur-oxidizing bacteria, Thiomonas sp., that subsequently remained dominant during the bioleaching process. Compared with iron-oxidizing bacteria, sulfur-oxidizing bacteria were more favorable to the pyrite-pyrolusite bioleaching system. Decreased pH due to microbial acid production was an important condition for bioleaching efficiency. Iron-oxidizing bacteria competed for pyrite reduction power with Mn(IV) in pyrolusite under specific conditions. These results extend our knowledge of microbial dynamics during pyrite-pyrolusite bioleaching, which is a key issue to improve commercial applications. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Coal-related research, organic chemistry, and catalysis

International Nuclear Information System (INIS)

Anon.

1980-01-01

Coal chemistry research topics included: H exchange at 400 0 C, breaking C-C bonds in coal, molecular weight estimation using small-angle neutron scattering, 13 C NMR spectra of coals, and tunneling during H/D isotope effects. Studies of coal conversion chemistry included thermolysis of bibenzyl and 1-naphthol, heating of coals in phenol, advanced indirect liquefaction based on Koelbel slurry Fischer-Tropsch reactor, and plasma oxidation of coal minerals. Reactions of PAHs in molten SbCl 3 , a hydrocracking catalyst, were studied. Finally, heterogeneous catalysis (desulfurization etc.) was studied using Cu, Au, and Ni surfaces. 7 figures, 6 tables

Micronized Coal Reburning Demonstration for NOx Control: A DOE Assessment; FINAL

International Nuclear Information System (INIS)

National Energy Technology Laboratory

2001-01-01

The goal of the U.S. Department of Energy's (DOE) Clean Coal Technology (CCT) program is to furnish the energy marketplace with a number of advanced, more efficient, and environmentally responsible coal utilization technologies through demonstration projects. These projects seek to establish the commercial feasibility of the most promising advanced coal technologies that have developed beyond the proof-of-concept stage. This document serves as a DOE post-project assessment of a project selected in CCT Round IV, the Micronized Coal Reburning (MCR) Demonstration for NO(sub x) Control, as described in a report to Congress (U.S. Department of Energy 1999). The need to meet strict emissions requirements at a minimum cost prompted the Tennessee Valley Authority (TVA), in conjunction with Fuller Company, Energy and Environmental Research Corporation (EER), and Fluor Daniel, to submit the proposal for this project to be sited at TVA's Shawnee Fossil Plant. In July 1992, TVA entered into a cooperative agreement with DOE to conduct the study. However, because of operational and environmental compliance strategy changes, the Shawnee site became unavailable

Modeling of integrated environmental control systems for coal-fired power plants. Final report

Energy Technology Data Exchange (ETDEWEB)

Rubin, E.S.; Salmento, J.S.; Frey, H.C.; Abu-Baker, A.; Berkenpas, M.

1991-05-01

The Integrated Environmental Control Model (IECM) was designed to permit the systematic evaluation of environmental control options for pulverized coal-fired (PC) power plants. Of special interest was the ability to compare the performance and cost of advanced pollution control systems to ``conventional`` technologies for the control of particulate, SO{sub 2} and NO{sub x}. Of importance also was the ability to consider pre-combustion, combustion and post-combustion control methods employed alone or in combination to meet tough air pollution emission standards. Finally, the ability to conduct probabilistic analyses is a unique capability of the IECM. Key results are characterized as distribution functions rather than as single deterministic values. (VC)

Prevention of formation of acid drainage from high-sulfur coal refuse by inhibition of iron- and sulfur-oxidizing microorganisms. 1. Preliminary experiments in controlled shaken flasks

Energy Technology Data Exchange (ETDEWEB)

Dugan, P.R.

1987-01-01

Changes of pH and sulfate concentration in high-sulfur coal refuse slurries are used as measurements of microbial pyrite oxidation in the laboratory. Sodium lauryl sulfate (SLS), alkylbenzene sulfonate (ABS), benzoic acid (BZ) and combinations of SLS plus BZ and ABS plus BZ effectively inhibited formation of sulfate and acid when added in concentrations greater than 50 mg/l to inoculated 20 or 30% coal refuse slurries. Here 25 mg/l concentrations of SLS, ABS and ABS plus BZ stimulated acid production. Formic, hexanoic, oxalic, propionic, and pyruvic acids at 0.1% concentrations were also effective inhibitors. Four different lignin sulfonates were only slightly effective inhibitors at 0.1% concentrations. It was concluded that acid formation resulting from microbial oxidation in high-sulfur coal refuse can be inhibited. 22 references.

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.

Arsenopyrite and pyrite bioleaching: evidence from XPS, XRD and ICP techniques.

Science.gov (United States)

Fantauzzi, Marzia; Licheri, Cristina; Atzei, Davide; Loi, Giovanni; Elsener, Bernhard; Rossi, Giovanni; Rossi, Antonella

2011-10-01

In this work, a multi-technical bulk and surface analytical approach was used to investigate the bioleaching of a pyrite and arsenopyrite flotation concentrate with a mixed microflora mainly consisting of Acidithiobacillus ferrooxidans. X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and X-ray-induced Auger electron spectroscopy mineral surfaces investigations, along with inductively coupled plasma-atomic emission spectroscopy and carbon, hydrogen, nitrogen and sulphur determination (CHNS) analyses, were carried out prior and after bioleaching. The flotation concentrate was a mixture of pyrite (FeS(2)) and arsenopyrite (FeAsS); after bioleaching, 95% of the initial content of pyrite and 85% of arsenopyrite were dissolved. The chemical state of the main elements (Fe, As and S) at the surface of the bioreactor feed particles and of the residue after bioleaching was investigated by X-ray photoelectron and X-ray excited Auger electron spectroscopy. After bioleaching, no signals of iron, arsenic and sulphur originating from pyrite and arsenopyrite were detected, confirming a strong oxidation and the dissolution of the particles. On the surfaces of the mineral residue particles, elemental sulphur as reaction intermediate of the leaching process and precipitated secondary phases (Fe-OOH and jarosite), together with adsorbed arsenates, was detected. Evidence of microbial cells adhesion at mineral surfaces was also produced: carbon and nitrogen were revealed by CHNS, and nitrogen was also detected on the bioleached surfaces by XPS. This was attributed to the deposition, on the mineral surfaces, of the remnants of a bio-film consisting of an extra-cellular polymer layer that had favoured the bacterial action. © Springer-Verlag 2011

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...

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.)

Studies for the stabilization of coal-oil mixtures. Final report, August 1978-May 1981

Energy Technology Data Exchange (ETDEWEB)

Botsaris, G.D.; Glazman, Y.M.; Adams-Viola, M.

1981-01-01

A fundamental understanding of the stabilization of coal-oil mixtures (COM) was developed. Aggregation of the coal particles was determined to control both the sedimentation and rheological properties of the COM. Sedimentation stability of COM prepared with coal, 80% < 200 mesh, is achieved by particle aggregation, which leads to the formation of a network of particles throughout the oil. The wettability of coal powders was evaluated by the Pickering emulsion test and a spherical agglomeration test to assess its effect on the stability of various COM formulations. Sedimentation stability of hydrophilic coal-oil-water mixtures (COWM) involves the formation of water bridges between the coal particles, while less stabilization of oleophilic COWM is achieved by the formation of an emulsion. Anionic SAA were least sensitive to the coal type and enhanced the aggregation stability of the suspension. The effect of cationic SAA, nonionic SAA and polymer additives depended upon the specific chemical structure of the SAA, the water content of the COM and the type of coal. The sedimentation stability of ultrafine COM was not directly due to the fineness of the powder but due to the formation of a network of flocculated particles.

Effect of sewage sludge on formation of acidic ground water at a reclaimed coal mine

International Nuclear Information System (INIS)

Cravotta, C.A. III

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 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 (< 5-m depth) from sludge-treated spoil (pH 5.9) were not elevated relative to untreated spoil (pH 4.4). In contrast, concentrations of nitrate were elevated in vadose water samples from sludge-treated spoil, frequently exceeding 10 mg/L. Downgradient decreases in nitrate to less than 3 mg/L and increases in sulfate concentrations in underlying ground water could result from 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

Coal supply and transportation markets during Phase One: Change, risk and opportunity. Final report

International Nuclear Information System (INIS)

Heller, J.N.; Kaplan, S.

1996-01-01

The Clean Air Act Amendments of 1990 (CAAA) required many utilities to sharply reduce sulfur emissions by January 1, 1995. This study describes and analyzes how the coal and transportation markets responded to this major development. The study focuses on five key coal supply regions and their associated transportation networks: the Uinta Basin (Colorado/Utah), Wyoming Powder River Basin, Illinois Basin, Monongahela region (Pittsburgh seam) and the central Appalachian region. From these regional studies, the report identifies key risk areas for future coal planning and general lessons for the fuels planning process. The study provides statistical information on coal production, demand, and transportation flows for each region. The analysis for each region focuses on developments which were generally unexpected; e.g., the relatively large volumes of medium-sulfur coal produced in the Illinois Basin and Monongahela region, the eastern penetration of Utah and Colorado coals, and the relatively modest growth in demand for central Appalachian coals. These developments generally worked to the advantage of utilities; i.e., medium- and low-sulfur coal was available at a lower price, in greater volumes and from a wider range of sources than many had expected. Utilities both took advantage of and helped to encourage these developments in the coal and transportation market. Looking ahead to Phase 11 strategies and future coal procurement, a major challenge will be to maintain the choice among supply and transportation alternatives which was so important to utility success in Phase 1. The report identifies rail transportation to be the major area of risk in most regions

Microbial desulfurization of coal

International Nuclear Information System (INIS)

Bos, P.; Boogerd, F.C.; Kuenen, J.G.

1992-01-01

In recent years, studies have been initiated to explore the possibilities of the use of biological systems in coal technology. This chapter discusses the principles behind the bioprocessing of coal, the advantages and disadvantages, and the economic feasibility of the process. For large-scale, coal-using, energy-producing plants, stack gas cleaning should be the treatment of choice. Biodesulfurization is preferable with industrial, small-scale, energy-producing plants. Treatment of the stack gases of these plants is not advisable because of high investment costs. Finally, it should be realized that biodesulfurization produces a waste stream that needs further treatment. 91 refs

Determining the radiative properties of pulverized-coal particles from experiments. Final report

Energy Technology Data Exchange (ETDEWEB)

Menguec, M.P.

1992-02-01

A comprehensive coupled experimental-theoretical study has been performed to determine the effective radiative properties of pulverized-coal/char particles. The results obtained show that the ``effective`` scattering phase function of coal particles are highly forward scattering and show less sensitivity to the size than predicted from the Lorenz-Mie theory. The main reason for this is the presence of smaller size particles associated with each larger particle. Also, the coal/char particle clouds display more side scattering than predicted for the same size range spheres, indicating the irregular shape of the particles and fragmentation. In addition to these, it was observed that in the visible wavelength range the coal absorption is not gray, and slightly vary with the wavelength. These two experimental approaches followed in this study are unique in a sense that the physics of the problem are not approximated. The properties determined include all uncertainties related to the particle shape, size distribution, inhomogeneity and spectral complex index of refraction data. In order to obtain radiative property data over a wider wavelength spectrum, additional ex-situ experiments have been carried out using a Fourier Transform Infrared (FT-IR) Spectrometer. The spectral measurements were performed over the wavelength range of 2 to 22 {mu}m. These results were interpreted to obtain the ``effective`` efficiency factors of coal particles and the corresponding refractive index values. The results clearly show that the coal/char radiative properties display significant wavelength dependency in the infrared spectrum.

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.

Unpacking paleoenvironmental change across OAE2 using paired d34S records of pyrite and organic matter

Science.gov (United States)

Raven, M. R.; Gomes, M.; Fike, D. A.

2017-12-01

Pyrite sulfur isotopes have proven to be a powerful tool for reconstructing major changes in global redox state and the emergence of microbial metabolisms. Still, pyrite can be a challenging archive, as its formation depends on the availability of reactive iron species and can occur over multiple generations of sedimentary processes. Accordingly, pyrite δ34S records commonly have large point-to-point variability reflecting local processes. By pairing pyrite δ34S records with those of coexisting organic matter (OM), including both kerogens and extractable bitumens, we can begin to parse the various potential causes of this variability and gain greater insights into changes in the sedimentary paleoenvironment. Here, we present the first collection of records of OM δ34S for the Cretaceous, focusing on sections spanning Ocean Anoxic Event 2 (OAE2, 94 Mya), a period of globally widespread marine anoxia and carbon cycle disruption. In carbonates and shales from OAE2 in Pont d'Issole, France, pyrite and OM δ34S values vary in parallel throughout most of the section, consistent with their shared sulfide source. There are also distinct exceptions: In one interval, an excursion in pyrite δ34S is entirely absent from the organic sulfur record but associated with unusual organic sulfur redox speciation (by XAS), potentially reflecting later exposure to oxic porewaters. Across the core interval of shale deposition during OAE2, the offset between pyrite and OM δ34S values declines smoothly from +17.4 to -7.9‰, which we interpret in terms of changes in the speciation of detrital iron minerals that may have regional implications. We then compare these results with data for other well-characterized OAE2 sections, including Cismon (Italy), Tarfaya (Morocco), and the Demerara Rise (offshore Brazil), which represent environments with a variety of apparent redox states. These paired pyrite - OM δ34S profiles yield new information about how the local and global forcings

Nuclear assay of coal. Volume 1. Coal composition by prompt neutron activation analysis: basic experiments. Final report

International Nuclear Information System (INIS)

Reynolds, G.; Bozorganesh, H.; Elias, E.; Gozani, T.; Maung, T.; Orphan, V.

1979-01-01

Using californium-252 as a source of exciting neutrons, prompt gamma photons emitted by elemental nuclei in the coal have been measured using several detectors, including sodium--iodide and germanium--lithium. Several coal types, including bituminous, subbituminous lignite and anthracite were crushed to various top sizes and analyzed carefully be traditional ASTM wet chemistry techniques at two or three different laboratories. The elements (sulfur, hydrogen, carbon, aluminum, silicon, iron, calcium, sodium, nitrogen, and chlorine) were determined by prompt neutron activations and the quantities compared with those of the wet chemical analyses

Too little oil, too much coal: Optimal carbon tax and when to phase in oil, coal and renewables

OpenAIRE

van der Ploeg, Frederick; Withagen, Cees A.

2011-01-01

Our main message is that it is optimal to use less coal and more oil once one takes account of coal being a backstop which emits much more CO2 than oil. The way of achieving this is to have a steeply rising carbon tax during the initial oil-only phase, a less-steeply rising carbon tax during the intermediate phase where oil and coal are used alongside each other and the following coal-only phase, and a flat carbon tax during the final renewables-only phase. The "laissez-faire" outcome uses co...

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.

Coal distribution, January--June 1991

International Nuclear Information System (INIS)

1991-01-01

The Coal Distribution report provides information on coal production, distribution, and stocks in the United States to a wide audience including Congress, Federal and State agencies, the coal industry, and the general public. The data in this report are collected and published by the Energy Information Administration (EIA) to fulfill its data collection and dissemination responsibilities as specified in the Federal Energy Administration Act of 1974 (Public Law 93-275, Sections 5 and 13, as amended). This issue presents information for January through June 1991. Coal distribution data are shown (in Tables 1--34) by coal-producing Sate of origin, consumer use, method of transportation, and State of destination. All data in this report were collected by the EIA on Form EIA-6, ''Coal Distribution Report.'' A copy of the form and the instructions for filing appear in Appendix B. All data in this report for 1991 are preliminary. Data for previous years are final. 6 figs., 34 tabs

Black coal. Annual report 1997

International Nuclear Information System (INIS)

1997-01-01

An overview is given of the situation of the world energy industry with regard to all energy carriers. Then energy-political conclusions are drawn for German black coal and the resulting prospects are detailed. Finally, some socio-political aspects are considered with regard to German black-coal mining: Workforce policy, tariff policy, social security and social safeguards for the adaptation process. (orig.) [de

A study of Multistage/Multifunction Column for Fine Coal Cleaning CRADA PC93-005, Final Report; FINAL

International Nuclear Information System (INIS)

Ralph Lai; Shiao-Hung Chiang; Daxin He; Yuru Feng

1998-01-01

The overall objective of the this research project is to explore the potential applicability of a multistage column for fine coal cleaning and other applications in fluid particle separation. The research work identifies the design parameters and their effects on the performance of the separation device. The results of this study provide an engineering data basis for further development of this technology in coal cleaning and in general areas of fluid and particle separations

Oxygen isotope evidence for sorption of molecular oxygen to pyrite surface sites and incorporation into sulfate in oxidation experiments

International Nuclear Information System (INIS)

Tichomirowa, Marion; Junghans, Manuela

2009-01-01

Experiments were conducted to investigate (i) the rate of O-isotope exchange between SO 4 and water molecules at low pH and surface temperatures typical for conditions of acid mine drainage (AMD) and (ii) the O- and S-isotope composition of sulfates produced by pyrite oxidation under closed and open conditions (limited and free access of atmospheric O 2 ) to identify the O source/s in sulfide oxidation (water or atmospheric molecular O 2 ) and to better understand the pyrite oxidation pathway. An O-isotope exchange between SO 4 and water was observed over a pH range of 0-2 only at 50 deg. C, whereas no exchange occurred at lower temperatures over a period of 8 a. The calculated half-time of the exchange rate for 50 deg. C (pH = 0 and 1) is in good agreement with former experimental data for higher and lower temperatures and excludes the possibility of isotope exchange for typical AMD conditions (T ≤ 25 deg. C, pH ≥ 3) for decades. Pyrite oxidation experiments revealed two dependencies of the O-isotope composition of dissolved sulfates: O-isotope values decreased with longer duration of experiments and increasing grain size of pyrite. Both changes are interpreted as evidence for chemisorption of molecular O 2 to pyrite surface sites. The sorption of molecular O 2 is important at initial oxidation stages and more abundant in finer grained pyrite fractions and leads to its incorporation in the produced SO 4 . The calculated bulk contribution of atmospheric O 2 in the dissolved SO 4 reached up to 50% during initial oxidation stages (first 5 days, pH 2, fine-grained pyrite fraction) and decreased to less than 20% after about 100 days. Based on the direct incorporation of molecular O 2 in the early-formed sulfates, chemisorption and electron transfer of molecular O 2 on S sites of the pyrite surface are proposed, in addition to chemisorption on Fe sites. After about 10 days, the O of all newly-formed sulfates originates only from water, indicating direct interaction

Cooperative research in coal liquefaction. Final report, May 1, 1992--April 30, 1993

Energy Technology Data Exchange (ETDEWEB)

Huffman, G.P. [ed.

1996-03-01

Research on sulfate and metal (Mo, Sn) promoted Fe{sub 2}O{sub 3} catalysts in the current year focused on optimization of conditions. Parameters varied included temperature, solvent, solvent-to-coal ratio, and the effect of presulfiding versus in situ sulfiding. Oil yields were found to increase approximately proportionately with both temperature and solvent-to-coal ratio. The donor solvent, tetralin, proved to give better total conversion and oil yields than either 1-methylnaphthalene or Wilsonville recycle oil. A significant enhancement of both total liquefaction yields and oil yields from lignites and subbituminous coals has been achieved by incorporating iron into the coal matrix by cation exchange. A study has been conducted on the synthesis of iron, molybdenum, and tungsten catalysts using a laser pyrolysis technique.

Characterization and supply of coal based fuels. Volume 1, Final report and appendix A (Topical report)

Energy Technology Data Exchange (ETDEWEB)

1992-06-01

Studies and data applicable for fuel markets and coal resource assessments were reviewed and evaluated to provide both guidelines and specifications for premium quality coal-based fuels. The fuels supplied under this contract were provided for testing of advanced combustors being developed under Pittsburgh Energy Technology Center (PETC) sponsorship for use in the residential, commercial and light industrial (RCLI) market sectors. The requirements of the combustor development contractors were surveyed and periodically updated to satisfy the evolving needs based on design and test experience. Available coals were screened and candidate coals were selected for further detailed characterization and preparation for delivery. A team of participants was assembled to provide fuels in both coal-water fuel (CWF) and dry ultrafine coal (DUC) forms. Information about major US coal fields was correlated with market needs analysis. Coal fields with major reserves of low sulfur coal that could be potentially amenable to premium coal-based fuels specifications were identified. The fuels requirements were focused in terms of market, equipment and resource constraints. With this basis, the coals selected for developmental testing satisfy the most stringent fuel requirements and utilize available current deep-cleaning capabilities.

Width design for gobs and isolated coal pillars based on overall burst-instability prevention in coal mines

Directory of Open Access Journals (Sweden)

Junfei Zhang

2016-08-01

Full Text Available An investigation was conducted on the overall burst-instability of isolated coal pillars by means of the possibility index diagnosis method (PIDM. First, the abutment pressure calculation model of the gob in side direction was established to derive the abutment pressure distribution curve of the isolated coal pillar. Second, the overall burst-instability ratio of the isolated coal pillars was defined. Finally, the PIDM was utilized to judge the possibility of overall burst-instability and recoverability of isolated coal pillars. The results show that an overall burst-instability may occur due to a large gob width or a small pillar width. If the width of the isolated coal pillar is not large enough, the shallow coal seam will be damaged at first, and then the high abutment pressure will be transferred to the deep coal seam, which may cause an overall burst-instability accident. This approach can be adopted to design widths of gobs and isolated coal pillars and to evaluate whether an existing isolated coal pillar is recoverable in skip-mining mines.

Simulated aerobic pedogenesis in pyritic overburden with a positive acid-base account

Energy Technology Data Exchange (ETDEWEB)

Doolittle, J.J.; Hossner, L.R.; Wilding, L.P. (South Dakota State University, Brookings, SD (United States). Dept. of Plant Science)

Reclamation of surface-mined land is often hindered by the excess salts and acidity produced by the weathering of pyritic overburden. This study was conducted to document the initial transformations that occur when pyritic overburden containing excess acid neutralizing potential is used as parent material in minesoil construction. An overburden containing 0.8% FeS[sub 2] (pyrite) and 1.6% inorganic carbonate (predominantly dolomite) was collected from the highwall of an active lignite surface mine in Panola County, Texas. The overburden was lightly crushed through a 13-mm sieve and packed into three replicate lysimeters (0.75 by 0.75 by 1.2 m). The lysimeters were leached monthly with 63.5 mm of deionized water for 24 mo. The initial material had a pH of 8.3 and an excess acid neutralizing potential. Progressive FeS[sub 2] oxidation released H[sub 2]SO[sub 4], and the pH decreased to 6.8. The dolomite dissolved, neutralizing the acidity, with subsequent release of Ca and Mg ions into solution. Leachate Ca[sup 2+] and SO[sub 4][sup 2-] concentrations exceeded the ion activity product of gypsum in the lower 60 cm of the lysimeters. Thin-section analysis revealed that gypsum crystals precipitated along margins of residual pyrite particles and in conductive vughs and channels. The continued accumulation of gypsum in minesoil development could eventually lead to the formation of a gypsic or a petrogypsic horizon. A restrictive layer such as this would decrease vertical movement of water and O[sub 2] which would reduce vegetative growth, increase runoff and erosion, and thus increase the probability of reclamation failure.

Analysis of ecological environment impact of coal exploitation and utilization

Science.gov (United States)

Zhang, Baoliu; Luo, Hong; Lv, Lianhong; Wang, Jian; Zhang, Baoshi

2018-02-01

Based on the theory of life cycle assessment, the ecological and environmental impacts of coal mining, processing, utilization and transportation will be analyzed, with analysing the status of china’s coal exploitation and utilization as the basis, it will find out the ecological and environmental impact in the development and utilization of coal, mainly consist of ecological impact including land damage, water resource destructionand biodiversity loss, etc., while the environmental impact include air, water, solid waste pollutions. Finally with a summary of the ecological and environmental problems, to propose solutionsand countermeasures to promote the rational development and consumption of coal, as well as to reduce the impact of coal production and consumption on the ecological environment, finally to achieve the coordinated development of energy and the environment.

Chemomechanical phenomena in the grinding of coal. Final report, February 1, 1976--May 31, 1977

Energy Technology Data Exchange (ETDEWEB)

Macmillan, N.H.

1977-08-01

Vickers microhardness, drilling rate, grinding rate and zeta-potential measurements have been made on coals of various rank in both aqueous and organic environments in order to determine whether: (a) chemomechanical (Rebinder) effects exist in coal; and (b) any such effects as do exist can be used to improve the comminution of coal. The results reveal the mechanical behavior of coal to be remarkably environment-insensitive as compared to inorganic non-metals. As a result, it is concluded that chemomechanical phenomena offer little prospect of reducing the cost of comminuting coal.

Gelatin/DMSO. A new approach to enhancing the performance of a pyrite electrode in a lithium battery

Energy Technology Data Exchange (ETDEWEB)

Montoro, L.A.; Rosolen, J.M. [Department of Chemistry, FFCLRP-University of Sao Paulo, 14040-901 Ribeirao Preto, Sao Paulo (Brazil)

2003-04-01

We have studied the electrochemical behavior of natural pyrite (FeS{sub 1.9}, n-type semiconductor) treated nonaqueously with dimethylsulfoxide (DMSO) solvent and also with a gelatin/DMSO solution. Composite electrodes (comprised of pyrite, polyvinilidene fluoride, polyethylene oxide and carbon) were characterized in a lithium cell at room temperature by cyclic voltammetry and galvanostatic measurements; the electrolyte used was LiPF{sub 6} in a solution of ethylene carbonate and dimethyl carbonate (1 mol l{sup -1}). The gelatin/DMSO treatment greatly improved the reversible specific capacity of a pyrite electrode. For galvanostatic discharge/charge at a current density of 0.4 mA cm{sup -2} and between voltage limits of 3.2 and 1.1 V, its reversible specific capacity at the 15th cycle equaled 275 mA h g{sup -1}, an impressive value compared to less than 25 mA h g{sup -1} for a pristine pyrite electrode.

British coal-down to the line

International Nuclear Information System (INIS)

Anon.

1993-01-01

The long-running saga of British Coal's decline is in its final stages with virtually no change from last October when the British government announced plants to close 31 of the 50 remaining mines. That announcement produced a political outcry but having privatized the electricity industry in 1990 the government had effectively left itself up the creek without a paddle. It had no powers to force the generators to buy more coal. The status of the British coal industry is discussed

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.

Mercury stable isotope signatures of world coal deposits and historical coal combustion emissions.

Science.gov (United States)

Sun, Ruoyu; Sonke, Jeroen E; Heimbürger, Lars-Eric; Belkin, Harvey E; Liu, Guijian; Shome, Debasish; Cukrowska, Ewa; Liousse, Catherine; Pokrovsky, Oleg S; Streets, David G

2014-07-01

Mercury (Hg) emissions from coal combustion contribute approximately half of anthropogenic Hg emissions to the atmosphere. With the implementation of the first legally binding UNEP treaty aimed at reducing anthropogenic Hg emissions, the identification and traceability of Hg emissions from different countries/regions are critically important. Here, we present a comprehensive world coal Hg stable isotope database including 108 new coal samples from major coal-producing deposits in South Africa, China, Europe, India, Indonesia, Mongolia, former USSR, and the U.S. A 4.7‰ range in δ(202)Hg (-3.9 to 0.8‰) and a 1‰ range in Δ(199)Hg (-0.6 to 0.4‰) are observed. Fourteen (p coal Hg emissions tracing. A revised coal combustion Hg isotope fractionation model is presented, and suggests that gaseous elemental coal Hg emissions are enriched in the heavier Hg isotopes relative to oxidized forms of emitted Hg. The model explains to first order the published δ(202)Hg observations on near-field Hg deposition from a power plant and global scale atmospheric gaseous Hg. Yet, model uncertainties appear too large at present to permit straightforward Hg isotope source identification of atmospheric forms of Hg. Finally, global historical (1850-2008) coal Hg isotope emission curves were modeled and indicate modern-day mean δ(202)Hg and Δ(199)Hg values for bulk coal emissions of -1.2 ± 0.5‰ (1SD) and 0.05 ± 0.06‰ (1SD).

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.

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.

1988 coal price negotiation

Energy Technology Data Exchange (ETDEWEB)

Senmura, Akira

1988-12-01

In the negotiation on raw coal price for 1988, which began at the end of 1987, Australia requested price rise of 4 - 5 dollars for the reason of rise of Australian dollars, conditions of mines, price drop in the past five years, and world supply/demand of coal. Japan insisted to maintain the price of preceding year. The talk ended in a dead lock which could last a long time. Negotiation on the Canadian coal price also encountered difficulties but an agreement was obtained in March as Japan accepted the increased price. After which, Japan and Australia agreed to raise the price by 2.90 dollars and an increase over last year. Producing countries also requested a wide price rise as 7.50 dollars for general coal, making in this area very difficult to progress. Finally, they agreed to raise the price by 6.30 dollars and the electric power utility in Japan responded by importing of U.S. coal, which has a lower heat output but is also cheaper. It depends on Australia for 70% of coal supply but started to diversify the source. 3 tabs.

Collaborative Studies for Mercury Characterization in Coal and Coal Combustion Products, Republic of South Africa

Science.gov (United States)

Kolker, Allan; Senior, Constance L.; van Alphen, Chris

2014-12-15

Mercury (Hg) analyses were obtained for 42 samples of feed coal provided by Eskom, the national electric utility of South Africa, representing all 13 coal-fired power stations operated by Eskom in South Africa. This sampling includes results for three older power stations returned to service starting in the late 2000s. These stations were not sampled in the most recent previous study. Mercury concentrations determined in the present study are similar to or slightly lower than those previously reported, and input Hg for the three stations returned to service is comparable to that for the other 10 power stations. Determination of halogen contents of the 42 feed coals confirms that chlorine contents are generally low, and as such, the extent of Hg self-capture by particulate control devices (PCDs) is rather limited. Eight density separates of a South African Highveld (#4) coal were also provided by Eskom, and these show a strong mineralogical association of Hg (and arsenic) with pyrite. The density separates were used to predict Hg and ash contents of coal products used in South Africa or exported. A suite of 48 paired samples of pulverization-mill feed coal and fly ash collected in a previous (2010) United Nations Environment Programme-sponsored study of emissions from the Duvha and Kendal power stations was obtained for further investigation in the present study. These samples show that in each station, Hg capture varies by boiler unit and confirms that units equipped with fabric filters for air pollution control are much more effective in capturing Hg than those equipped with electrostatic precipitators. Apart from tracking the performance of PCDs individually, changes resulting in improved mercury capture of the Eskom fleet are discussed. These include Hg reduction through coal selection and washing, as well as through optimization of equipment and operational parameters. Operational changes leading to increased mercury capture include increasing mercury

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)

Integrated coal preparation

International Nuclear Information System (INIS)

Buchanan, D.J.; Jones, T.F.

1992-01-01

Perceptions of quality have changed over the years. The attributes of a certain coal (its rank, slagging propensity, ash content etc) are traditionally referred to as its quality. However, the subject of this paper is quality in a much wider sense: quality as fitness for purpose: and all that such a wide definition entails. British Standard BS 5750 (ISO 9000) Quality Systems defines a systems approach to quality, and includes both the supplier of raw materials and the final customer within this boundary. Coal preparation starts at the production face. The greater the proportion of dirt in run-of-mine product the greater the challenge in satisfying the customer's needs. Significant advances have been made in minimizing mined dirt. For example, the sue of vertical steering on longwall faces improves productivity and quality. Unfortunately modern mining methods produce large quantities of fines, despite efforts to reduce them at the point of production and during transportation to the surface. Coal preparation also produces further fines. It has been estimated that fine coal costs 2.5 times as much to clean as large coal, and the costs of handing wet fine coal product will inflate this estimate. Handling considerations rightly concern our customers and are part of the wider meaning of quality. In this paper the authors address some novel solutions to the challenge posed by fines

Element geochemistry and cleaning potential of the No. 11 coal seam from Antaibao mining district

Energy Technology Data Exchange (ETDEWEB)

Wang, W.F.; Qin, Y.; Song, D.Y.; Sang, S.X.; Jiang, B.; Zhu, Y.M.; Fu, X.H. [China University of Mining & Technology, Xuzhou (China). College for Resources & Geoscience

2005-12-15

Based on the analyses of sulfur and 41 other elements in 8 channel samples of the No. 11 coal seam from Antaibao surface mine, Shanxi, China and 4 samples from the coal preparation plant of this mine, the distribution of the elements in the seam profile, their geochemical partitioning behavior during the coal cleaning and the genetic relationships between the both are studied. The coal-forming environment was probably invaded by sea water during the post-stage of peatification, which results in the fact that the contents of As, Fe, S, etc. associated closely with sea water tend to increase toward the top of the seam. These elements studied are dominantly associated with kaolinite, pyrite, illite, montmorillonite, etc., of which the As, Pb, Mn, Cs, Co, Ni, etc. are mainly associated with sulfides, the Mo, V, Nb, Hf, REEs, Ta etc. mainly with kaolinite, the Mg, Al etc. mainly with epigenetic montmorillonite, and the Rb, Cr, Ba, Cu, K, Hg, etc. mainly with epigenetic illite. The physical coal cleaning is not only effective in the removal of ash and sulfur, but also in reducing the concentration of most major and trace elements. The elements Be, U, Sb, W, Br, Se, P, etc. are largely or partly organically bound showing a relatively low removability, while the removability of the other elements studied is more than 20%, of which the Mg, Mn, Hg, Fe, As, K, AI, Cs, and Cr associated mostly with the coarser or epigenetic minerals show a higher removability than that of ash. The distribution of the elements in the seam profile controls their partitioning behavior to a great degree during the coal cleaning processes.

Mobilisation and attenuation of boron during coal mine rehabilitation, Wangaloa, New Zealand

International Nuclear Information System (INIS)

Craw, D.; Rufaut, C.G.; Haffert, L.; Todd, A.

2006-01-01

Environmental mobility and fate of boron has been traced from source to discharge waters through the rehabilitated Wangaloa coal mine in southern New Zealand. The boron is derived initially from coal, which has up to 450 mg/kg B. The coal also contains pyrite (2-5 wt.% S), which oxidizes to yield a low-pH environment (typical pH 2-5). Weathering of coal-bearing waste rock liberates B into rainwater that infiltrates into waste rock or evaporates to leave a gypsum crust enriched in B, possibly as boric acid or colemanite as inferred from geochemical modelling. Surface waters dissolve this evaporative material periodically, yielding total B concentrations up to 6 mg/L, at pH<4.5. Some of the available B is taken up by plants that have been established on the waste rock, resulting in foliage B concentrations of up to 230 mg/kg (dry weight). Partial attenuation of dissolved B by adsorption to iron oxyhydroxide occurs as groundwater passes through waste rock, but this is inhibited by adsorption competition with dissolved sulphate (up to 600 mg/L). Groundwater flows from the mine through a pit lake and wetland, with total dissolved B near 1 mg/kg after dilution and limited adsorption attenuation has occurred. Despite the widespread B mobility throughout the rehabilitated mine, there is little evidence of B toxicity in plants. The B concentrations in discharging waters are in the environmentally safe range for most aquatic organisms, being neither deficient in B as a micronutrient, nor boron-toxic. (author)

Transformation of sulfur during pyrolysis and hydropyrolysis of coal

Energy Technology Data Exchange (ETDEWEB)

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

1998-05-01

It is reported that the transformation of sulfur during pyrolysis (Py) under nitrogen and hydropyrolysis (HyPy) of Chinese Yanzhou high sulfur bituminous coal and Hongmiao lignite was studied in a fixed-bed reactor. The volatile sulfur-containing products were determined by gas chromatography with flame photometric detection. The sulfur in initial coal and char (mainly aliphatic and thiophenic sulfur forms) was quantitatively analyzed using X-ray photoelectron spectroscopy (XPS). The desulfurization yield was calculated by elemental analysis. The main volatile sulfur-containing gas was H{sub 2}S in both Py and HyPy. Both the elemental analysis and XPS results indicated that more sulfur was removed in HyPy than in Py under nitrogen. Thiophenic sulfur can be partially hydrogenated and removed in HyPy. Pyrite can be reduced to a ferrous sulfide completely even as low as 400{degree}C in HyPy while in Py the reduction reaction continues up to 650{degree}C. Mineral matter can not only fix H{sub 2}S produced in Py and HyPy to form higher sulfur content chars but also catalyses the desulfurization reactions to form lower sulfur content tars in HyPy. 24 refs., 8 figs., 4 tabs.

Effects of calcium magnesium acetate on the combustion of coal-water slurries. Final project report, 1 September 1989--28 February 1993

Energy Technology Data Exchange (ETDEWEB)

Levendis, Y.A.; Wise, D.; Metghalchi, H.; Cumper, J.; Atal, A.; Estrada, K.R.; Murphy, B.; Steciak, J.; Hottel, H.C.; Simons, G.

1993-07-01

To conduct studies on the combustion of coal water fuels (CWFs) an appropriate facility was designed and constructed. The main components were (1) a high-temperature isothermal laminar flow furnace that facilitates observation of combustion events in its interior. The design of this system and its characterization are described in Chapter 1. (2) Apparatus for slurry droplet/agglomerate particle generation and introduction in the furnace. These devices are described in Chapters 1 and 3 and other attached publications. (3) An electronic optical pyrometer whose design, construction theory of operation, calibration and performance are presented in Chapter 2. (4) A multitude of other accessories, such as particle fluidization devices, a suction thermometer, a velocimeter, high speed photographic equipment, calibration devices for the pyrometer, etc., are described throughout this report. Results on the combustion of CWF droplets and CWF agglomerates made from micronized coal are described in Chapter 3. In the same chapter the combustion of CWF containing dissolved calcium magnesium acetate (CMA) axe described. The combustion behavior of pre-dried CWF agglomerates of pulverized grain coal is contrasted to that of agglomerates of micronized coal in Chapter 4. In the same chapter the combustion of agglomerates of carbon black and diesel soot is discussed as well. The effect of CMA on the combustion of the above materials is also discussed. Finally, the sulfur capture capability of CMA impregnated micronized and pulverized bituminous coals is examined in Chapter 5.

NEW SOLID FUELS FROM COAL AND BIOMASS WASTE; FINAL

International Nuclear Information System (INIS)

Hamid Farzan

2001-01-01

Under DOE sponsorship, McDermott Technology, Inc. (MTI), Babcock and Wilcox Company (B and W), and Minergy Corporation developed and evaluated a sludge derived fuel (SDF) made from sewage sludge. Our approach is to dry and agglomerate the sludge, combine it with a fluxing agent, if necessary, and co-fire the resulting fuel with coal in a cyclone boiler to recover the energy and to vitrify mineral matter into a non-leachable product. This product can then be used in the construction industry. A literature search showed that there is significant variability of the sludge fuel properties from a given wastewater plant (seasonal and/or day-to-day changes) or from different wastewater plants. A large sewage sludge sample (30 tons) from a municipal wastewater treatment facility was collected, dried, pelletized and successfully co-fired with coal in a cyclone-equipped pilot. Several sludge particle size distributions were tested. Finer sludge particle size distributions, similar to the standard B and W size distribution for sub-bituminous coal, showed the best combustion and slagging performance. Up to 74.6% and 78.9% sludge was successfully co-fired with pulverized coal and with natural gas, respectively. An economic evaluation on a 25-MW power plant showed the viability of co-firing the optimum SDF in a power generation application. The return on equity was 22 to 31%, adequate to attract investors and allow a full-scale project to proceed. Additional market research and engineering will be required to verify the economic assumptions. Areas to focus on are: plant detail design and detail capital cost estimates, market research into possible project locations, sludge availability at the proposed project locations, market research into electric energy sales and renewable energy sales opportunities at the proposed project location. As a result of this program, wastes that are currently not being used and considered an environmental problem will be processed into a renewable

Evaluation of technology modifications required to apply clean coal technologies in Russian utilities. Final report

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-12-01

The report describes the following: overview of the Russian power industry; electric power equipment of Russia; power industry development forecast for Russia; clean coal technology demonstration program of the US Department of Energy; reduction of coal TPS (thermal power station) environmental impacts in Russia; and base options of advanced coal thermal power plants. Terms of the application of clean coal technology at Russian TPS are discussed in the Conclusions.

Acid-base properties of a limed pyritic overburden during simulated weathering

Energy Technology Data Exchange (ETDEWEB)

Doolittle, J.J.; Hossner, L.R. [South Dakota State University, Brookings, SD (United States). Plant Science Dept.

1997-11-01

Surface-mine reclamation is often hindered by the formation of acid mine soil and acid mine drainage from FeS{sub 2} oxidation. Surface soils containing FeS{sub 2} are often treated with crushed limestone (predominately CaCO{sub 3}) to prevent aid minesoil formation. The main objective of this study was to evaluate the long-term effectiveness of liming pyritic minesoil to prevent the formation of acid minesoil and acid mine drainage. Pyritic minesoils that did not receive lime became acidic very rapidly and produced acidic leachate. Almost all of the FeS{sub 2} in this treatment oxidized during the first 200 d. The addition of lime at a rate of 25% of the theoretical acid-base account (ABA) significantly slowed FeS{sub 2} oxidation, but rapid oxidation ensued after the added lime was neutralized. Treatments receiving a liming rate of 50% ABA or greater remained neutral to alkaline throughout the study. Acid-base values and residual FeS{sub 2}-CO{sub 3} data, however, indicate that the lime was dissolving from the system faster than the FeS{sub 2} was oxidizing, and all the treatments would eventually become acidic. The results indicate that the liming of a pyritic overburden to an ABA of 125% is not a sustainable solution to preventing acid minesoil and acid mine drainage. 25 refs., 6 figs., 3 tabs.

Terrestrial sedimentary pyrites as a potential source of trace metal release to groundwater – A case study from the Emsland, Germany

International Nuclear Information System (INIS)

Houben, Georg J.; Sitnikova, Maria A.; Post, Vincent E.A.

2017-01-01

Pyrite is a common minor constituent of terrestrial freshwater sediments and a sink for trace elements. Different amounts and morphological types (framboids and euhedral crystals) of sedimentary pyrites were found in the heavy mineral fraction of cores obtained from several drillholes located in the Emsland region, NW Germany. Their trace element contents were investigated to assess their potential for groundwater contamination after oxidation, e.g. induced by dewatering or autotrophic denitrification. Nickel, arsenic and cadmium were found in significant concentrations in pyrite. Geochemical modeling showed that elevated trace metal concentrations in groundwater, potentially exceeding drinking water standards, should preferentially occur in a less than 1 m thick zone situated around the depth of the redoxcline, where nitrate is reduced by pyrite. This was confirmed by depth-specific groundwater sampling in the Emsland and by previously published studies. The absolute concentration of released trace metals depends on their content in the pyrite but also strongly on the nitrate load of groundwater. - Highlights: • Pyrite from heavy mineral fraction of aquifer sediment analyzed for trace metal content. • Pyrites contain significant concentration of trace metals, such as nickel, arsenic, cadmium. • Trace elements are released by autotrophic denitrification. • Reactive transport model predicts small zone of trace element accumulation. • Release of trace elements strongly dependent on nitrate content of groundwater.

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.

Surface chemistry of pyrite during the pre-processing for the flotation in alkaline sodium carbonate medium during uranium ore processing

International Nuclear Information System (INIS)

Neudert, A.; Sommer, H.; Schubert, H.

1991-01-01

It is often necessary during processing of uranium ore to flotate pyrite at sodium carbonate alkaline pH value caused by the subsequent hydrometallurgical process stages. It was found out by ESCA analyses that the pyrite surface changes chemically prior to the addition of flotation agents. FeS 2 becomes FeO within a few hours in the case of storage in process water; limonite and/or geothite result from pyrite. The copper ions of the activator CuSO 4 are exclusively monovalent on the pyrite surface. The resulting heavy metal xanthogenate is Cu(I) xanthogenate. Conclusions are derived for the flotation practice for the intensification of the reagent regime. (orig./HP) [de

Belgium's burning coal tips. Coupling thermographic ASTER imagery with topography to map debris slide susceptibility

Energy Technology Data Exchange (ETDEWEB)

Nyssen, Jan; Diependaele, Stijn; Goossens, Rudi [Ghent Univ. (Belgium). Dept. of Geography

2012-03-15

Burning coal tips and the debris slides induced by this combustion are a potential danger for local residents and visitors, and a method is required to identify areas of susceptibility. The relatively easy circulation of air, enhanced by the poor compaction of the spoil heaps, and the exothermic reaction of pyrite with oxygen may ignite coal tips. Rainwater infiltration and subsequent evaporation inside burning coal tips may create steam pressure, which, combined with humidity and slope steepness can then trigger landsliding. Based on mapping of debris slides and susceptibility factors such as burning (represented by positive surface temperature anomalies on thermographic imagery) and slope gradient, this study aims to define thresholds for debris slide susceptibility on coal tips and to map potential debris slide source areas on spoil heaps. The Belgian coal tips were used as study area. A DTM as well as ASTER Kinetic Surface Temperature products were used to measure slope gradients and temperature anomaly. Locations with typical characteristics of combustion (heat, red soil colour, steam and gases), and debris slides were recorded in the field, and were used to identify thresholds beyond which debris sliding is generally observed: a temperature anomaly of > 0.5 K, when comparing the debris slide areas to the average temperature of the coal tip, and a slope gradient {>=} 28 . The susceptibility zones for debris slide detachment were mapped by considering the imagery pixels that exceeded the thresholds for temperature and slope gradient; the results fitted well when compared with the observed debris slides. The method can be improved by using more coal tips for calibration, and by taking into account rain depth and slope aspect. (orig.)

Low-rank coal research: Volume 2, Advanced research and technology development: Final report

Energy Technology Data Exchange (ETDEWEB)

Mann, M.D.; Swanson, M.L.; Benson, S.A.; Radonovich, L.; Steadman, E.N.; Sweeny, P.G.; McCollor, D.P.; Kleesattel, D.; Grow, D.; Falcone, S.K.

1987-04-01

Volume II contains articles on advanced combustion phenomena, combustion inorganic transformation; coal/char reactivity; liquefaction reactivity of low-rank coals, gasification ash and slag characterization, and fine particulate emissions. These articles have been entered individually into EDB and ERA. (LTN)

Quarterly coal statistics of OECD countries

Energy Technology Data Exchange (ETDEWEB)

1992-04-27

These quarterly statistics contain data from the fourth quarter 1990 to the fourth quarter 1991. The first set of tables (A1 to A30) show trends in production, trade, stock change and apparent consumption data for OECD countries. Tables B1 to B12 show detailed statistics for some major coal trade flows to and from OECD countries and average value in US dollars. A third set of tables, C1 to C12, show average import values and indices. The trade data have been extracted or derived from national and EEC customs statistics. An introductory section summarizes trends in coal supply and consumption, deliveries to thermal power stations; electricity production and final consumption of coal and tabulates EEC and Japanese steam coal and coking coal imports to major countries.

Impact of Sulphur Content on Coal Quality at Delta Plain Depositional Environment: Case study in Geramat District, Lahat Regency, South Sumatra

Directory of Open Access Journals (Sweden)

Siska Linda Sari

2017-09-01

Full Text Available The research was conducted in Geramat District of Lahat Regency, South Sumatra. An evaluation of the geological condition of the research area shown that the coal deposits were found in Muara Enim Formation as a coal-bearing formation. The method used was literature study, field observation and the laboratory work includes proximate and petrography analysis. The aim of this research is to determine the environmental condition of coal based on the change of total sulphur content and to know the relation between ash content to calorific value.  As the result of proximate analysis conducted on five samples of coal, the research area obtained total sulphur (0,21-1,54% adb, ash content (3,16 - 71,11% adb and gross calorific value (953 - 5676 cal/g. adb. Based on the result of maceral analysis showed the maceral percentage of coal in research area composed by vitrinite (77,8-87,4 %, liptinite (0,6 %, inertinite (8,0 – 17,6 % and mineral matter concentration in the form of pyrite (1,6-4,6 %. The average reflectance value of vitrinite (Rv of coal in the research area (0.54%. the results analysis shows that the coal in Muara Enim Formation on the research area is in the transitional lower delta plain depositional environment phase. Any changes in the sedimentary environment affected by sea water will be followed by changes in total sulphur and the higher ash content, on the contrary, the lower calorific value of the coal.

The origin of copiapite from chlorite pyritic schist (Wiesciszowice, Lower Silesia, Poland) in the light of Moessbauer analysis

Energy Technology Data Exchange (ETDEWEB)

Adamczyk, Z., E-mail: zdzislaw.adamczyk@polsl.pl [Silesian University of Technology, Institute of Applied Geology (Poland); Komraus, J. L., E-mail: komraus@us.edu.pl [University of Silesia, Institute of Physics (Poland)

2008-01-15

This work presents the results of the analysis of copiapite, formed from weathering and oxidation of pyrite in pyritic schist from Wiesciszowice, Lower Silesia (Poland). The pure phase of copiapite was found in secondary minerals after pyrite and identified by optical microscopy, XRD and Moessbauer spectroscopy. In the analyzed copiapite major cations appear to be Fe{sup 2+} and Fe{sup 3+}. Some Fe{sup 3+} is substituted by other cations, mainly Al{sup 3+}. Al{sup 3+} probably comes from leaching of chlorite from which hydrated sulphates of iron, mainly szomolnokite, form followed by hydrated sulphates fibroferrite, which is replaced by copiapite.

In situ remediation of hexavalent chromium with pyrite fines : bench scale demonstration

International Nuclear Information System (INIS)

Cathum, S.; Wong, W.P.; Brown, C.E.

2002-01-01

An in situ remediation technique for chromium contaminated soil with pyrite fines was presented. Past industrial activities and lack of disposal facilities have contributed to a serious problem dealing with chromium, which cannot be eliminated from the environment because it is an element. Both bench-scale and laboratory testing was conducted to confirm the efficiency of the proposed process which successfully converted Cr(VI) into Cr(III) in soil and water. Cr(III) is less toxic and immobile in the environment compared to Cr(VI) which moves freely in the soil matrix, posing a risk to the groundwater quality. pH in the range of 2.0 to 7.6 has no effect on the reactivity of pyrite towards Cr(VI). The optimization of the bench-scale treatment resulted in a large volume of chromium waste, mostly from the control experiments and column hydrology testing. These waste streams were treated according to municipal guidelines before disposal to the environment. Samples of chromium waste before and after treatment were analyzed. Cr (VI) was completely mineralized to below guideline levels. It was determined that several conditions, including contact time between pyrite and Cr(VI), are crucial for complete mineralization of Cr(VI). 13 refs., 8 tabs., 9 figs

Prediction of acid mine drainage generation potential of various lithologies using static tests: Etili coal mine (NW Turkey) as a case study.

Science.gov (United States)

Yucel, Deniz Sanliyuksel; Baba, Alper

2016-08-01

The Etili neighborhood in Can County (northwestern Turkey) has large reserves of coal and has been the site of many small- to medium-scale mining operations since the 1980s. Some of these have ceased working while others continue to operate. Once activities cease, the mining facilities and fields are usually abandoned without rehabilitation. The most significant environmental problem is acid mine drainage (AMD). This study was carried out to determine the acid generation potential of various lithological units in the Etili coal mine using static test methods. Seventeen samples were selected from areas with high acidic water concentrations: from different alteration zones belonging to volcanic rocks, from sedimentary rocks, and from coals and mine wastes. Static tests (paste pH, standard acid-base accounting, and net acid generation tests) were performed on these samples. The consistency of the static test results showed that oxidation of sulfide minerals, especially pyrite-which is widely found not only in the alteration zones of volcanic rocks but also in the coals and mine wastes-is the main factor controlling the generation of AMD in this mine. Lack of carbonate minerals in the region also increases the occurrence of AMD.

Fate of the naturally occurring radioactive materials during treatment of acid mine drainage with coal fly ash and aluminium hydroxide.

Science.gov (United States)

Madzivire, Godfrey; Maleka, Peane P; Vadapalli, Viswanath R K; Gitari, Wilson M; Lindsay, Robert; Petrik, Leslie F

2014-01-15

Mining of coal is very extensive and coal is mainly used to produce electricity. Coal power stations generate huge amounts of coal fly ash of which a small amount is used in the construction industry. Mining exposes pyrite containing rocks to H2O and O2. This results in the oxidation of FeS2 to form H2SO4. The acidic water, often termed acid mine drainage (AMD), causes dissolution of potentially toxic elements such as, Fe, Al, Mn and naturally occurring radioactive materials such as U and Th from the associated bedrock. This results in an outflow of AMD with high concentrations of sulphate ions, Fe, Al, Mn and naturally occurring radioactive materials. Treatment of AMD with coal fly ash has shown that good quality water can be produced which is suitable for irrigation purposes. Most of the potentially toxic elements (Fe, Al, Mn, etc) and substantial amounts of sulphate ions are removed during treatment with coal fly ash. This research endeavours to establish the fate of the radioactive materials in mine water with coal fly ash containing radioactive materials. It was established that coal fly ash treatment method was capable of removing radioactive materials from mine water to within the target water quality range for drinking water standards. The alpha and beta radioactivity of the mine water was reduced by 88% and 75% respectively. The reduced radioactivity in the mine water was due to greater than 90% removal of U and Th radioactive materials from the mine water after treatment with coal fly ash as ThO2 and UO2. No radioisotopes were found to leach from the coal fly ash into the mine water. Copyright © 2013 Elsevier Ltd. All rights reserved.

77 FR 56717 - Specifications for Medical Examinations of Underground Coal Miners

Science.gov (United States)

2012-09-13

... CFR Part 37 Specifications for Medical Examinations of Underground Coal Miners; Final Rule #0;#0... 0920-AA21 Specifications for Medical Examinations of Underground Coal Miners AGENCY: Centers for... medical examinations of underground coal miners. Existing regulations established specifications for...

Isotopic Tracing of Thallium Contamination in Soils Affected by Emissions from Coal-Fired Power Plants.

Science.gov (United States)

Vaněk, Aleš; Grösslová, Zuzana; Mihaljevič, Martin; Trubač, Jakub; Ettler, Vojtěch; Teper, Leslaw; Cabala, Jerzy; Rohovec, Jan; Zádorová, Tereza; Penížek, Vít; Pavlů, Lenka; Holubík, Ondřej; Němeček, Karel; Houška, Jakub; Drábek, Ondřej; Ash, Christopher

2016-09-20

Here, for the first time, we report the thallium (Tl) isotope record in moderately contaminated soils with contrasting land management (forest and meadow soils), which have been affected by emissions from coal-fired power plants. Our findings clearly demonstrate that Tl of anthropogenic (high-temperature) origin with light isotope composition was deposited onto the studied soils, where heavier Tl (ε(205)Tl ∼ -1) naturally occurs. The results show a positive linear relationship (R(2) = 0.71) between 1/Tl and the isotope record, as determined for all the soils and bedrocks, also indicative of binary Tl mixing between two dominant reservoirs. We also identified significant Tl isotope variations within the products from coal combustion and thermo-desorption experiments with local Tl-rich coal pyrite. Bottom ash exhibited the heaviest Tl isotope composition (ε(205)Tl ∼ 0), followed by fly ash (ε(205)Tl between -2.5 and -2.8) and volatile Tl fractions (ε(205)Tl between -6.2 and -10.3), suggesting partial Tl isotope fractionations. Despite the evident role of soil processes in the isotope redistributions, we demonstrate that Tl contamination can be traced in soils and propose that the isotope data represent a possible tool to aid our understanding of postdepositional Tl dynamics in surface environments for the future.

Primary immigration and succession of soil organisms on reclaimed opencast coal mining areas in eastern Germany

Energy Technology Data Exchange (ETDEWEB)

Wanner, M.; Dunger, W. [Staatliches Museum Naturkunde, Gorlitz (Germany)

2002-07-01

Immigration to and colonisation of recultivated opencast coal mining areas by soil organisms were investigated in eastern Germany during the period 1996-1998 in freshly exposed substrates (immigration test) and two up to 46-year-old afforested mine soils (stage-dependent succession). The results indicate that immigration by air is characteristic for protists, soil microarthropods and spiders, while active locomotion is more important for the soil macrofauna. Testate amoebae assemblages showed no evident differences between 30-37-year-old Tertiary afforestations (ash-ameliorated, pyrite-rich, low soil pH) and 46-year-old Pleistocene sites (liming, low pyrite content, moderate soil pH), while comparisons in soil animals revealed pronounced differences in abundance, biomass and species composition. Generally, all investigated soil animal groups indicated taxon-specific immigration and colonisation strategies with pronounced site preferences, dependent on substrate quality, age and afforestation. Within 40 years, a consistent trend is visible from an open pioneer to a woodland community. Furthermore, it was demonstrated that long-term investigations as well as numerous taxa of different trophic levels are essential for a comprehensive evaluation of recultivated mine dumps.

Coal geology and assessment of coal resources and reserves in the Powder River Basin, Wyoming and Montana

Science.gov (United States)

Luppens, James A.; Scott, David C.

2015-01-01

This report presents the final results of the first assessment of both coal resources and reserves for all significant coal beds in the entire Powder River Basin, northeastern Wyoming and southeastern Montana. The basin covers about 19,500 square miles, exclusive of the part of the basin within the Crow and Northern Cheyenne Indian Reservations in Montana. The Powder River Basin, which contains the largest resources of low-sulfur, low-ash, subbituminous coal in the United States, is the single most important coal basin in the United States. The U.S. Geological Survey used a geology-based assessment methodology to estimate an original coal resource of about 1.16 trillion short tons for 47 coal beds in the Powder River Basin; in-place (remaining) resources are about 1.15 trillion short tons. This is the first time that all beds were mapped individually over the entire basin. A total of 162 billion short tons of recoverable coal resources (coal reserve base) are estimated at a 10:1 stripping ratio or less. An estimated 25 billion short tons of that coal reserve base met the definition of reserves, which are resources that can be economically produced at or below the current sales price at the time of the evaluation. The total underground coal resource in coal beds 10–20 feet thick is estimated at 304 billion short tons.

A spatial analysis of China's coal flow

International Nuclear Information System (INIS)

Mou Dunguo; Li Zhi

2012-01-01

The characteristics of China's energy structure and the distribution of its coal resources make coal transportation a very important component of the energy system; moreover, coal transportation acts as a bottleneck for the Chinese economy. To insure the security of the coal supply, China has begun to build regional strategic coal reserves at some locations, but transportation is still the fundamental way to guaranty supply security. Here, we study China's coal transportation quantitatively with a linear programming method that analyses the direction and volume of China's coal flows with the prerequisite that each province's supply and demand balance is guaranteed. First, we analyse the optimal coal transportation for the status quo coal supply and demand given the bottleneck effects that the Daqin Railway has on China's coal flow; second, we analyse the influence of future shifts in the coal supply zone in the future, finding that China's coal flows will also change, which will pressure China to construct railways and ports; and finally, we analyse the possibility of exploiting Yangtze River capacity for coal transportation. We conclude the paper with suggestions for enhancing China's coal transportation security. - Highlights: ► We use linear programming to study China's coal transportation. ► First, analyse the optimal coal flow under the status quo condition. ► Second, analyse influences of coal supply zone shifts to Neimeng and Xinjiang. ► Third, analyse the influence of using Yangtze River for coal transportation. ► At last, we give suggestions about infrastructure construction to guaranty China's long-run coal supply security.

Influence of Sulfobacillus thermosulfidooxidans on Initial Attachment and Pyrite Leaching by Thermoacidophilic Archaeon Acidianus sp. DSM 29099

Directory of Open Access Journals (Sweden)

Jing Liu

2016-07-01

Full Text Available At the industrial scale, bioleaching of metal sulfides includes two main technologies, tank leaching and heap leaching. Fluctuations in temperature caused by the exothermic reactions in a heap have a pronounced effect on the growth of microbes and composition of mixed microbial populations. Currently, little is known on the influence of pre-colonized mesophiles or moderate thermophiles on the attachment and bioleaching efficiency by thermophiles. The objective of this study was to investigate the interspecies interactions of the moderate thermophile Sulfobacillus thermosulfidooxidans DSM 9293T and the thermophile Acidianus sp. DSM 29099 during initial attachment to and dissolution of pyrite. Our results showed that: (1 Acidianus sp. DSM 29099 interacted with S. thermosulfidooxidansT during initial attachment in mixed cultures. In particular, cell attachment was improved in mixed cultures compared to pure cultures alone; however, no improvement of pyrite leaching in mixed cultures compared with pure cultures was observed; (2 active or inactivated cells of S. thermosulfidooxidansT on pyrite inhibited or showed no influence on the initial attachment of Acidianus sp. DSM 29099, respectively, but both promoted its leaching efficiency; (3 S. thermosulfidooxidansT exudates did not enhance the initial attachment of Acidianus sp. DSM 29099 to pyrite, but greatly facilitated its pyrite dissolution efficiency. Our study provides insights into cell-cell interactions between moderate thermophiles and thermophiles and is helpful for understanding of the microbial interactions in a heap leaching environment.

Methane emissions from coal mining

International Nuclear Information System (INIS)

Williams, A.; Mitchell, C.

1993-01-01

This paper outlines some of the problems associated with the prediction of levels of methane emission from underground and surface coal mines. Current knowledge of coal mining emissions sources is outlined. On the basis of this information the methodology proposed by the IPCC/OECD Programme on National Inventories is critically examined and alternatives considered. Finally, the technical options for emissions control are examined together with their feasibility. 8 refs., 6 figs., 2 tabs

Matrix composition and community structure analysis of a novel bacterial pyrite leaching community.

Science.gov (United States)

Ziegler, Sibylle; Ackermann, Sonia; Majzlan, Juraj; Gescher, Johannes

2009-09-01

Here we describe a novel bacterial community that is embedded in a matrix of carbohydrates and bio/geochemical products of pyrite (FeS(2)) oxidation. This community grows in stalactite-like structures--snottites--on the ceiling of an abandoned pyrite mine at pH values of 2.2-2.6. The aqueous phase in the matrix contains 200 mM of sulfate and total iron concentrations of 60 mM. Micro-X-ray diffraction analysis showed that jarosite [(K,Na,H(3)O)Fe(3)(SO(4))(2)(OH)(6)] is the major mineral embedded in the snottites. X-ray absorption near-edge structure experiments revealed three different sulfur species. The major signal can be ascribed to sulfate, and the other two features may correspond to thiols and sulfoxides. Arabinose was detected as the major sugar component in the extracellular polymeric substance. Via restriction fragment length polymorphism analysis, a community was found that mainly consists of iron oxidizing Leptospirillum and Ferrovum species but also of bacteria that could be involved in dissimilatory sulfate and dissimilatory iron reduction. Each snottite can be regarded as a complex, self-contained consortium of bacterial species fuelled by the decomposition of pyrite.

An experimental study on the geochemical behavior of highly siderophile elements (HSE) and metalloids (As, Se, Sb, Te, Bi) in a mss-iss-pyrite system at 650 °C: A possible magmatic origin for Co-HSE-bearing pyrite and the role of metalloid-rich phases in the fractionation of HSE

Science.gov (United States)

Cafagna, Fabio; Jugo, Pedro J.

2016-04-01

Pyrite, the most abundant sulfide in the Earth's crust, is an accessory mineral in several magmatic sulfide deposits. Although most pyrite is hydrothermal, previous experimental studies have shown that pyrite can also have a primary magmatic origin, by exsolving from monosulfide solid solution (mss) during cooling of a sulfide melt, if sulfur fugacity is sufficiently high. Pyrite from some localities has significant amounts of Co, and complex zonation in some low-melting-point chalcophile elements (LMCE), such as As, Se, Sb, Te, Bi (henceforth referred to as metalloids) and some platinum-group elements (PGE: Ru, Rh, Pd, Os, Ir, Pt). However, the origin of such pyrite and the causes of zonation are not clear. Because the distribution of some of these elements is heterogeneous and seems to be developed in concentric zones, the zonation has been interpreted to represent growth stages, some of them secondary and caused partly by hydrothermal fluids. Better constraints on the origin of Co-PGE-bearing pyrite could help unravel the geochemical processes affecting the sulfide assemblages in which it is found; thus, an experimental study was undertaken to characterize pyrite formation in magmatic sulfide environments and its relationship with metalloids and highly siderophile elements (HSE: PGE, Re, Au). Natural pyrrhotite, chalcopyrite, pentlandite and elemental S were mixed and doped with approximately 50 ppm of each HSE. A mixture of metalloids was added at 0.2 wt.% or 3 wt.% to aliquots of sulfide mixtures. Starting materials were sealed in evacuated silica tubes and fused at 1200 °C. The temperature was subsequently reduced to 750 °C (at 60 °C/h), then to 650 °C (at 0.5 °C/h) to produce relatively large euhedral pyrite crystals, then quenched. The experiments were analyzed using reflected light, SEM, EPMA and LA-ICP-MS. Experimental products contained euhedral pyrite, mss, intermediate solid solution (iss) and metalloid-rich phases, interpreted as quench product

Computer application in coal preparation industry in China

Energy Technology Data Exchange (ETDEWEB)

Lu, M.; Wu, L.; Ni, Q. (China Univ. of Mining and Technology, Xuzhou (China))

1990-01-01

This paper describes several packages of microcomputer programs developed for designing and managing the coal preparation plants. Three parts are included: Coal Cleaning Package (CCP), Coal Preparation Optimization Program (CPO) and Coal Preparation Computer Aided Design System (CPCAD). The function of CCP is: evaluating and predicting coal cleaning result. Coal presentation process modelling and optimization; coal preparation flowsheet design and optimization. The CPO is a nonlinear optimization program. It can simulate and optimize the profit for different flowsheet to get the best combination of the final products. The CPCAD was developed based upon AutoCAD and makes full use of AutoLISP, digitizer menus and AutoCAD commands, combining the functions provided by AutoCAD and the principle used in conventional coal preparation plant design, forming a designer-oriented CPCAD system. These packages have proved to be reliable, flexible and easy to learn and use. They are a powerful tool for coal preparation plant design and management. (orig.).

H-coal fluid dynamics. Final report, August 1, 1977-December 31, 1979

Energy Technology Data Exchange (ETDEWEB)

1980-04-16

This report presents the results of work aimed at understanding the hydrodynamic behavior of the H-Coal reactor. A summary of the literature search related to the fluid dynamic behavior of gas/liquid/solid systems has been presented. Design details of a cold flow unit were discussed. The process design of this cold flow model followed practices established by HRI in their process development unit. The cold fow unit has been used to conduct experiments with nitrogen, kerosene, or kerosene/coal char slurries, and HDS catalyst, which at room temperature have properties similar to those existing in the H-Coal reactor. Mineral oil, a high-viscosity liquid, was also used. The volume fractions occupied by gas/liquid slurries and catalyst particles were determined by several experimental techniques. The use of a mini-computer for data collection and calculation has greatly accelerated the analysis and reporting of data. Data on nitrogen/kerosene/HDS catalyst and coal char fines are presented in this paper. Correlations identified in the literature search were utilized to analyze the data. From this analysis it became evident that the Richardson-Zaki correlation describes the effect of slurry flow rate on catalyst expansion. Three-phase fluidization data were analyzed with two models.

Materials, process, product analysis of coal process technology. Phase I final report

Energy Technology Data Exchange (ETDEWEB)

Saxton, J. C.; Roig, R. W.; Loridan, A.; Leggett, N. E.; Capell, R. G.; Humpstone, C. C.; Mudry, R. N.; Ayres, E.

1976-02-01

The purpose of materials-process-product analysis is a systematic evaluation of alternative manufacturing processes--in this case processes for converting coal into energy and material products that can supplement or replace petroleum-based products. The methodological steps in the analysis include: Definition of functional operations that enter into coal conversion processes, and modeling of alternative, competing methods to accomplish these functions; compilation of all feasible conversion processes that can be assembled from combinations of competing methods for the functional operations; systematic, iterative evaluation of all feasible conversion processes under a variety of economic situations, environmental constraints, and projected technological advances; and aggregative assessments (economic and environmental) of various industrial development scenarios. An integral part of the present project is additional development of the existing computer model to include: A data base for coal-related materials and coal conversion processes; and an algorithmic structure that facilitates the iterative, systematic evaluations in response to exogenously specified variables, such as tax policy, environmental limitations, and changes in process technology and costs. As an analytical tool, the analysis is intended to satisfy the needs of an analyst working at the process selection level, for example, with respect to the allocation of RDandD funds to competing technologies.

Solvent-refined-coal (SRC) process. Volume II. Sections V-XIV. Final report

Energy Technology Data Exchange (ETDEWEB)

1982-05-01

This report documents the completion of development work on the Solvent Refined Coal Process by The Pittsburgh and Midway Coal Mining Co. The work was initiated in 1966 under Office of Coal Research, US Department of Interior, Contract No. 14-01-0001-496 and completed under US Department of Energy Contract No. DE-AC05-79ET10104. This report discusses work leading to the development of the SRC-I and SRC-II processes, construction of the Fort Lewis Pilot Plant for the successful development of these processes, and results from the operation of this pilot plant. Process design data generated on a 1 ton-per-day Process Development Unit, bench-scale units and through numerous research projects in support of the design of major demonstration plants are also discussed in summary form and fully referenced in this report.

Dandruff, seborrheic dermatitis, and psoriasis drug products containing coal tar and menthol for over-the-counter human use; amendment to the monograph. Final rule

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-03-15

The Food and Drug Administration (FDA) is issuing a final rule amending the final monograph (FM) for over-the-counter (OTC) dandruff, seborrheic dermatitis, and psoriasis drug products to include the combination of 1.8 percent coal tar solution and 1.5 percent menthol in a shampoo drug product to control dandruff. FDA did not receive any comments or data in response to its previously proposed rule to include this combination. This final rule is part of FDA's ongoing review of OTC drug products.

Optimal carbon tax with a dirty backstop: Oil, coal, or renewables?

OpenAIRE

van der Ploeg, Frederick; Withagen, Cees A.

2011-01-01

Optimal climate policy is studied. Coal, the abundant resource, contributes more CO2 per unit of energy than the exhaustible resource, oil. We characterize the optimal sequencing oil and coal and departures from the Herfindahl rule. "Preference reversal" can take place. If coal is very dirty compared to oil, there is no simultaneous use. Else, the optimal outcome starts with oil, before using oil and coal together, and finally coal on its own. The "laissez-faire" outcome uses coal forever or ...

Australian coal prospects and response to air quality issues

International Nuclear Information System (INIS)

Cain, D.A.

1992-01-01

Australia is unique in its high dependency on coal as a domestic energy source and as a major export commodity. Coal provides about 41% of Australia's primary energy and is the country's largest export. Australia's domestic air quality issues and standards are reviewed and current Australian research aimed at reducing emissions from both bituminous and brown coal combustion is summarized. Australia's greenhouse policy is also discussed. The future role of coal in the world, particularly in the Asia-Pacific region, where three quarters of Australia's coal exports are sold, is reviewed. Forecasts of the world import demand for both metallurgical coal and thermal coal to the year 2000 are provided. The supply capacity of major coal exporting countries in summarized and estimates of export coal market shares in 2000 given. Finally, the future of Australia's domestic use of coal is discussed, in the light of climate change concerns

Evaluation, engineering and development of advanced cyclone processes. Final separating media evaluation and test report (FSMER)

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-05-19

{open_quotes}Evaluation Engineering and Development of Advanced Cyclone Processes{close_quotes} is one of the DOE-PETC sponsored advanced coal cleaning projects, which share a number of specific goals. These goals are to produce a 6% ash product, reject 85% of the parent coal`s pyritic sulfur, recover 85% of the parent coal`s Btu value, and provide products that are less than 30% moisture. The process in this project, as the name implies, relies on a cyclone or cyclonic separator to achieve physical beneficiation based on the gravimetric differences between clean coal and its impurities. Just as important as the cyclonic separator, if not more so, is the selection of a parting liquid or medium for use in the separator. Selection of a separating medium is regarded as a significant portion of the project because it has a profound impact on the required unit operations, the performance of the separator, and economics of the process. The choice of medium especially influences selection of media recovery system(s), and the characteristics of clean coal and refuse products. Since medium selection is such an important aspect of the project, portions of the project are dedicated to the study, evaluation, and selection of the most desirable medium. Though separators are an important component, this project initially focused on media study, rather than the separators themselves. In coal processing, discussion of media requires description of the handling and recovery system(s), separation performance, interaction with coal, cost, and health, environmental and safety issues. In order to be effective, a candidate must perform well in all of these categories.

Model-based analysis of δ34S signatures to trace sedimentary pyrite oxidation during managed aquifer recharge in a heterogeneous aquifer