Sample records for bastnaesite

  1. Kinetics of Rare Earth Extraction from Baotou Bastnaesite in Hydrochloric Acid and Aluminum Chloride (United States)

    Zhang, Xiao-Wei; Li, Mei; Liu, Zhao-Gang; Hu, Yan-Hong; Wang, Mi-Tang


    In this paper, the leaching kinetics of rare earth from Baotou bastnaesite in a HCl-AlCl3 solution was investigated. In addition, the effects of the HCl and AlCl3 concentrations, liquid to solid ratio, stirring speed, temperature, and time spent on the rare earth extraction were determined. The results indicated that the extraction was nearly independent of the stirring speed when it did not exceed 300 rpm, and the rate of leaching increased with increases in the HCl and AlCl3 concentrations, liquid to solid ratio, temperature, and time. The optimum dissolution conditions were determined under five experimental conditions. After leaching occurred, the progressive dissolution of the bastnaesite phase could be determined. The leaching kinetics was analyzed with a new variant of the shrinking core model in which both the interfacial transfer and diffusion across the product layer affected the rare earth extraction. The apparent activation energy was 35.57 kJ/mol, and the Arrhenius constant was 341.58 min-1. An empirical equation was derived to describe the extraction process of rare earth minerals.

  2. Physical and chemical mechanism underlying ultrasonically enhanced hydrochloric acid leaching of non-oxidative roasting of bastnaesite. (United States)

    Zhang, Dongliang; Li, Mei; Gao, Kai; Li, Jianfei; Yan, Yujun; Liu, Xingyu


    In this study, we investigated an alternative to the conventional hydrochloric acid leaching of roasted bastnaesite. The studies suggested that the rare earth oxyfluorides in non-oxidatively roasted bastnaesite can be selectively leached only at elevated temperatures Further, the Ce(IV) in oxidatively roasted bastnaesite does not leach readily at low temperatures, and it is difficult to induce it to form a complex with F - ions in order to increase the leaching efficiency. Moreover, it is inevitably reduced to Ce(III) at elevated temperatures. Thus, the ultrasonically-assisted hydrochloric acid leaching of non-oxidatively roasted bastnaesite was studied in detail, including, the effects of several process factors and the, physical and chemical mechanisms underlying the leaching process. The results show that the leaching rate for the ultrasonically assisted process at 55°C (65% rare earth oxides) is almost the same as that for the conventional leaching process at 85°C. Based on the obtained results, it is concluded that ultrasonic cavitation plays a key role in the proposed process, resulting not only in a high shear stress, which damages the solid surface, but also in the formation of hydroxyl radicals (OH) and hydrogen peroxide (H 2 O 2 ). Standard electrode potential analysis and experimental results indicate that Ce(III) isoxidized by the hydroxyl radicals to Ce(IV), which can be leached with F - ions in the form of a complex, and that the Ce(IV) can subsequently be reduced to Ce(III) by the H 2 O 2. This prevents the Cl - ions in the solution from being oxidized to form chlorine. These results imply that the ultrasonically-assisted process can be used for the leaching of non-oxidatively roasted bastnaesite at low temperatures in the absence of a reductant. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. On the Origin of Bastnaesite-(La,Nd,Y in the Nissi (Patitira Bauxite Laterite Deposit, Lokris, Greece

    Directory of Open Access Journals (Sweden)

    Sofia Kalatha


    Full Text Available A detailed geochemical study and a thorough mineralogical description of the rare-earth elements (REE-minerals and associated minerals were carried out in two vertical profiles of approximately 4 m length, from the Nissi (Patitira bauxite laterite deposit, Lokris, Greece, characterized by the presence of goethite in small sizes resembling bacterial cell coated by goethite and a significant REE enrichment. The enrichment of the REE concentrated in bastnaesite-group minerals, the intergrowths between REE-minerals and Al–Ni–silicates with significant sulfur contents and their association with goethite microtextures interpreted as bacteriomorphic, indicate REE remobilization along with iron bio-leaching and re-precipitation on karstified limestone. In addition to the previous-reported hydroxylbastnaesites, a (La,Nd,Y(CO3F member of the bastnaesite-group associated with Al–Ni–silicates were identified, the stability of which may reflect the dependence on the source rocks and the local variations of pH-Eh. Interaction between downward percolating water and carbonate rocks seems to be a very effective mechanism for REE fluorocarbonates deposition under alkaline and reducing conditions.

  4. Leaching of Light Rare Earth Elements from Sichuan Bastnaesite: A Facile Process to Leach Trivalent Rare Earth Elements Selectively from Tetravalent Cerium (United States)

    Shen, Yueyue; Jiang, Ying; Qiu, Xianying; Zhao, Shilin


    The effects of the nitric acid concentration, leaching time, leaching temperature, and solid-to-liquid ratio on leaching efficiency were examined. From those results, a facile process for the selective leaching of trivalent rare earth elements (RE(III)) from tetravalent cerium (Ce(IV)) was proposed. The roasted bastnaesite was used to leach 34.87% of RE(III) and 2.15% of Ce(IV) at 60°C for 0.5 h with an acid concentration of 0.5 mol/L. This selective leaching process can be described by the shrinking-core model that follows the kinetic model 1 - 2/3 α - (1 - α)2/3. Subsequently, the leached slag was hydrothermally treated and followed by thorough leaching with 4.0-mol/L nitric acid. Furthermore, the specific surface area of the final leached slag is 57.7 m2/g, which is approximately 650 times higher than that of raw ore. Finally, selective leaching of RE(III) (>90%) was achieved without using an organic solvent for extraction, whereas lower value Ce(IV)was presented in the leached slag (>92%).

  5. Process for rare earth separation

    International Nuclear Information System (INIS)

    Leveque, A.; Le Loarer, J.L.


    Separation process of neodymium and eventually praseodymium from rare earths contained in fluocarbonated ores and especially bastnaesite by calcination, leaching with nitric acid and liquid-liquid extraction [fr

  6. International strategic minerals inventory summary report; rare-earth oxides (United States)

    Jackson, W.D.; Christiansen, Grey


    Bastnaesite, monazite, and xenotime are currently the most important rare-earth minerals. Bastnaesite occurs as a primary mineral in carbonatites. Monazite and xenotime also can be found in primary deposits but are recovered principally from heavy-mineral placers that are mined for titanium or tin. Each of these minerals has a different composition of the 15 rare-earth elements. World resources of economically exploitable rare-earth oxides (REO) are estimated at 93.4 million metric tons in place, composed of 93 percent in primary deposits and 7 percent in placers. The average mineral composition is 83 percent bastnaesite, 13 percent monazite, and 4 percent of 10 other minerals. Annual global production is about 67,000 metric tons of which 41 percent is from placers and 59 percent is from primary deposits; mining methods consist of open pits (94 percent) and dredging (6 percent). This output could be doubled if the operations that do not currently recover rare earths would do so. Resources are more than sufficient to meet the demand for the predictable future. About 52 percent of the world's REO resources are located in China. Ranking of other countries is as follows: Namibia (22 percent), the United States (15 percent), Australia (6 percent), and India (3 percent); the remainder is in several other countries. Conversely, 38 percent of the production is in China, 33 percent in the United States, 12 percent in Australia, and 5 percent each in Malaysia and India. Several other countries, including Brazil, Canada, South Africa, Sri Lanka, and Thailand, make up the remainder. Markets for rare earths are mainly in the metallurgical, magnet, ceramic, electronic, chemical, and optical industries. Rare earths improve the physical and rolling properties of iron and steel and add corrosion resistance and strength to structural members at high temperatures. Samarium and neodymium are used in lightweight, powerful magnets for electric motors. Cerium and yttrium increase the

  7. A selective spectrophotometric determination of europium in mixtures with other lanthanides, yttrium and scandium

    International Nuclear Information System (INIS)

    Lyle, S.J.; Za'tar, N.A.


    Spectrophotometric methods are presented for the determination of 0.04-5 mg of europium in rare earth mixtures, following a group separation, or in lanthanide compounds. Europium(III) is selectively reduced on a Jones reductor to europium(II) which in turn reduces molybdophosphoric acid to a molybdenum blue. The absorbance is measured at 810 nm in aqueous solution or at 790 nm after extraction into n-amyl alcohol; optimal reaction conditions and times are reported. Other rare earth elements, and chloride, bromide, perchlorate, acetate and sulphate, are without effect when present in gram amounts but nitrate and iodide must be absent. The method is applied to the determination of europium in various lanthanide oxides and bastnaesite. (Auth.)

  8. Determination of Tb, Dy, Ho, Er and Yb in ores and concentrates by ICP-OES method

    International Nuclear Information System (INIS)

    Kanicky, V.; Toman, J.; Malecek, M.


    Optical emission spectroscopy was used (OES) to analyse apatite from the Kola peninsula with a total content of 0.9% oxides of heavy rare earth elements, the hydroxide concentrate of apatite, the oxide concentrate of rare earth elements, bastnaesite minerals and raw materials containing monasite. Measurements were made with a PV 8210/8280 spectrometer (width of spectral interval in the 1st order of the spectrum 0.028 mm) and an ICP PV 8490 generator. The spectra were measured of 19 most sensitive analytical lines of heavy rare earth elements (8 Tb, 3 Dy, 1 Ho, 3 Er, 4 Yb). The mutual interferences of the different elements, detection limits and resolution limits were determined. The results of the determination of rare earth elements and of certain general elements in the analysed raw materials are tabulated. (E.S.). 2 figs., 11 tabs., 10 refs

  9. Aeromagnetic expression of rare earth element (REE) deposits in New Mexico, USA (United States)

    Li, M.


    With the development of high-tech devices and the expanding demands in industrial production, rare earth elements(REE) has been playing an increasingly important role in the global economy in the past several decades. Different types of REE serve irreplaceable functions in high-tech industry, as well as for developing sustainable energy and catalysis of manufacturing. Given that the global supply of REE has become strained since 2009 and no known substitutes for REE have been found, exploration for new REE deposits is imperative for economic sustainability. Ten main regions have REE deposits in New Mexico, some of which have not been exploited, while some sites such as Gallinas mountains vein deposits are in early exploration stage. Exploration for the reserves and quantization of mineral compositions of New Mexico's REE depositional districts can have economic benefits in general. In this study, high-resolution airborne magnetic and gravity data were used for studying the Gallinas mountains REE deposit. The purposes of this study are to: (1) characterize specific aeromagnetic anomaly and gravity features from the REE deposits, and (2) apply the characterized features to suggest other areas among the ten REE depositional regions for further exploration. All REE deposits in the study area are found associated with alkaline to alkali-calcic volcanic rocks. A quantitative modeling based on aeromagnetic and gravity anomaly mapping was constructed with an assumption of three units: carbonatites, alkaline volcanic intrusions and REE-concentrated minerals (barite, bastnaesite, etc.). The results of this study show that alkaline deposit is characterized by negative magnetic anomalies and carbonatite is associated with gravity anomaly and vertical gravity gradient high. The area with significantly high aeromagnetic anomaly area and also gravity anomaly high supposed to reflect REE-concentrated minerals such as bastnaesite. For further research, hyperspectral information and

  10. Sedimentary carbonate-hosted giant Bayan Obo REE-Fe-Nb ore deposit of Inner Mongolia, China; a cornerstone example for giant polymetallic ore deposits of hydrothermal origin (United States)

    Chao, E.C.T.; Back, J.M.; Minkin, J.A.; Tatsumoto, M.; Junwen, Wang; Conrad, J.E.; McKee, E.H.; Zonglin, Hou; Qingrun, Meng; Shengguang, Huang


    Detailed, integrative field and laboratory studies of the textures, structures, chemical characteristics, and isotopically determined ages and signatures of mineralization of the Bayan Obo deposit provided evidence for the origin and characteristics favorable for its formation and parameters necessary for defining giant polymetallic deposits of hydrothermal origin. Bayan Obo is an epigenetic, metasomatic, hydrothermal rare earth element (REE)-Fe-Nb ore deposit that is hosted in the metasedimentary H8 dolostone marble of the Middle Proterozoic Bayan Obo Group. The metasedimentary sequence was deposited on the northern continental slope of the North China craton. The mine area is about 100 km south of the suture marking Caledonian subduction of the Mongolian oceanic plate from the north beneath the North China craton. The mineralogy of the deposit is very complex, consisting of more than 120 different minerals, some of which are epigenetic minerals introduced by hydrothermal solutions, and some of which are primary and secondary metamorphic minerals. The major REE minerals are monazite and bastnaesite, whereas magnetite and hematite are the dominant Fe-ore minerals, and columbite is the most abundant Nb mineral. Dolomite, alkali amphibole, fluorite, barite, aegirine augite, apatite, phlogopite, albite, and microcline are the most widespread gangue minerals. Three general types of ores occur at Bayan Obo: disseminated, banded, and massive ores. Broad zoning of these ore types occurs in the Main and East Orebodies. Disseminated ores are in the outermost zone, banded ores are in the intermediate zone, and massive ores are in the cores of the orebodies. On the basis of field relations, host rocks, textures, structures, and mineral assemblages, many varieties of these three types of ores have been recognized and mapped. Isotopic dating of monazite, bastnaesite, aeschynite, and metamorphic and metasomatic alkali amphiboles associated with the deposit provides constraints

  11. Technology development for recovery of individual rare earth elements at high purity from Dong-Pao rare earth concentrated ore of Vietnam

    International Nuclear Information System (INIS)

    Hoang Nhuan; Le Ba Thuan; Luu Xuan Dinh; Tran Hoang Mai; Tran Thi Hong Thai; Yoshiuyki Aiba; Hiroaki Nishimura


    In this work, the research results on RE processing process at laboratory scale and pilot scale was reported and discussed. Experimental research on thermal decomposition and sulfate process of bastnaesite ore with sulfuric acid in electric furnace was carried out, the different roasting conditions, mass transfer rate, reactions and RE and/or non-RE behaviors during roasting and leaching were investigated. The roasting temperatures were 450 o C and 550 o C. With higher roasting temperature and longer roasting time, the RE recovery yield reduced. The RE recovery yield reached the highest (over 94%) at roasting temperature of 550 o C for 2 hrs. The different extracting conditions for separation of REEs were investigated in laboratory scale as well as pilot scale. At pilot scale, the separation of REEs was performed on 120-stage extraction system produced by Japan, using PC88A solvent dissolved in IP2028. The volume of each stage was 20 L. The results showed that REEs were separated from RE resource of Vietnam and individual RE elements such as La, Ce, Pr, and Nd were obtained at high purity. The parameters for each extraction stage were reported in this work. The results indicated that in order to obtain highly purified Nd (>99%), it needs to use an extraction system with higher stage number, about 200 stages. The extraction data at pilot scale of this investigation was used as basic data for calculating parameters for extraction system in industrial scale. (author)

  12. Decoupling of Mg-C and Sr-Nd-O isotopes traces the role of recycled carbon in magnesiocarbonatites from the Tarim Large Igneous Province (United States)

    Cheng, Zhiguo; Zhang, Zhaochong; Hou, Tong; Santosh, M.; Chen, Lili; Ke, Shan; Xu, Lijuan


    The Tarim Large Igneous Province in NW China hosts numerous magmatic carbonatite dikes along its northern margin. The carbonatites are composed mainly of dolomite (90 vol.%) and minor calcite (5 vol.%), with apatite, barite, celestine, aegirine, monazite and bastnaesite as accessory minerals. The rocks correspond to magnesiocarbonatites with a compositional range of 13.73-19.59 wt.% MgO, and 20.03-30.11 wt.% CaO, along with 1.65-3.31 wt.% total Fe2O3, 0.02-2.39 wt.% SiO2 and other minor elements, such as P2O5, Na2O and K2O. These magnesiocarbonatites are characterized by extreme enrichment in incompatible elements with high total rare earth element (REE) contents of 372-36965 ppm. The strontium [(87Sr/86Sr)i = 0.70378-0.70386], neodymium [εNd(t) = +2.51 - +3.59] and oxygen (δ18OV-SMOW = 5.9‰-8.0‰) isotope values of these rocks are consistent with a mantle origin, whereas the magnesium (δ26Mg = -1.09‰ to -0.85‰) and carbon (δ13CV-PDB = -4.1‰ to -5.9‰) isotopes are decoupled from mantle values and reflect signature of recycled sedimentary carbonates. Global plate tectonic models predict that sedimentary carbonates in convergent margins are subducted to deep domains in the mantle, with phase transitions from calcite/dolomite to magnesite, and eventually to periclase/perovskite. The involvement of a mantle plume enhances the normal mantle geotherms and promotes decomposition reactions of magnesite. The decoupling of Mg-C and Sr-Nd-O isotopes in the mangesiocarbonatites provides insights on the origin of carbonatites, and also illustrates a case of interaction between mantle plume and subduction-related components.

  13. Fluorbritholite-(Y) and yttrialite-(Y) from silexites of the Keivy alkali granites, Kola Peninsula (United States)

    Lyalina, L. M.; Zozulya, D. R.; Savchenko, Ye. E.; Tarasov, M. P.; Selivanova, E. A.; Tarasova, E.


    Investigation of the morphology, anatomy, and chemical composition of fluorbritholite-(Y) and yttrialite-(Y) from silexites of the Keivy alkali granites in Kola Peninsula has shown that these minerals are the main REE concentrators in this area and that their content reaches 10-15 vol %. Britholite and yttrialite are associated with zircon, aeschynite-(Y), chevkinite-(Ce), fergusonite-(Y), thorite, monazite-(Ce), xenotime-(Y) and bastnaesite-(Ce). Three morphological types of fluorbritholite-(Y) have been identified: (I) subhedral crystals and grains, (II) anhedral grains intergrown with yttrialite-(Y), and (III) poikilitic crystals and skeletal aggregates. These morphological types of fluorbritholite-(Y) are characterized by successive (I to III type) decreases in P content down to the pure silicate fluorbritholite-(Y). Crystals of the first type are heterogenous: the P content decreases and the HREE content increases from core to rim. The total REE content increases insignificantly from types I to II and drastically decreases in fluorbritholite-(Y) of type III. The successive prevalence of HREE over LREE indicates the hydrothermal conditions of mineral crystallization. The chemical composition of yttrialite-(Y) is distinguished by the relatively high Th content and depletion in Al. The compositional trend (from core to rim) in heterogeneous grains of yttrialite-(Y) testifies that their heterogeneity was caused by metasomatic alteration of the mineral. The interrelation of fluorbritholite-(Y) and yttrialite-(Y) indicate that fluorbritholite-(Y) of types II and III were formed later than yttrialite-(Y). Evidence for fluorbritholite-(Y) and yttrialite-(Y) formation suggests the significant role of hydrothermal processes in the genesis of silexites.

  14. Host-rock controlled epigenetic, hydrothermal metasomatic origin of the Bayan Obo REEFe-Nb ore deposit, Inner Mongolia, P.R.C. (United States)

    Chao, E.C.T.; Back, J.M.; Minkin, J.A.; Yinchen, R.


    Bayan Obo, a complex rare earth element (REE)FeNb ore deposit, located in Inner Mongolia, P.R.C. is the world's largest known REE deposit. The deposit is chiefly in a marble unit (H8), but extends into an overlying unit of black shale, slate and schist unit (H9), both of which are in the upper part of the Middle Proterozoic Bayan Obo Group. Based on sedimentary structures, the presence of detrital quartz and algal fossil remains, and the 16-km long geographic extent, the H8 marble is a sedimentary deposit, and not a carbonatite of magmatic origin, as proposed by some previous investigators. The unit was weakly regionally metamorphosed (most probably the lower part of the green schist facies) into marble and quartzite prior to mineralization. Tectonically, the deposit is located on the northern flank of the Sino-Korean craton. Many hypotheses have been proposed for the origin of the Bayan Obo deposit; the studies reported here support an epigenetic, hydrothermal, metasomatic origin. Such an origin is supported by field and laboratory textural evidence; 232Th/208Pb internal isochron mineral ages of selected monazite and bastnaesite samples; 40Ar/39Ar incremental heating minimum mineral ages of selected alkali amphiboles; chemical compositions of different generations of both REE ore minerals and alkali amphiboles; and evidence of host-rock influence on the various types of Bayan Obo ores. The internal isochron ages of the REE minerals indicate Caledonian ages for various episodes of REE and Fe mineralization. No evidence was found to indicate a genetic relation between the extensive biotite granitic rocks of Hercynian age in the mine region and the Bayan Obo are deposit, as suggested by previous workers. ?? 1992.

  15. REE enrichment due to fenitization of Devonian granites, Rodeo de Los Molles, Central Argentina (United States)

    Lorenz, M.; Altenberger, U.; Trumbull, R. B.; Lira, R.; Lopez De Luchi, M. G.; Viñas, N.


    The Rodeo de Los Molles rare earth element (REE) mineralization is characterized by an uncommon REE-bearing assemblage located within a fenitized biotite-monzogranite. The fenitization is found in a NNE-SSW trending, possibly fault related elliptical body in the northern margin of the Devonian Las Chacras-Piedras Coloradas Batholith, San Luis province, Central Argentina. The fenite was produced by the metasomatic addition of K and Na, as well as the loss of Ca and Sr, leading to the transformation of monzogranite to (quartz) alkali-feldspar syenite composition. Whole-rock geochemistry revealed a local enrichment in light rare earth elements within the fenitized zone. Drill-core samples from a mineral exploration campaign (Lira et al., 1999) and new surface samples are the basis for the present investigation, which aims to decipher the fluid evolution and REE-mineralization. REE-bearing minerals are located in irregularly patches and nodules ranging from a few millimeters to more than one meter in diameter. The REE-rich assemblage comprises an intergrowth of primary britholite (Ce,Ca)5(SiO4, PO4)3(OH,F), allanite and apatite with aegirine-augite, titanite, fluorite, bastnaesite and, quartz as well as complex thorium-rich accessory minerals. In more intensely altered areas clinochlore, spherolitic quartz, calcite, kaolinite, hematite and phlogopite also occur. Britholite is an extraordinary mineral belonging to the apatite group, usually described as an accessory mineral. Aside from being one of only three localites in the world where it occurs in ore quantities, Rodeo de Los Molles further contains atypical huge aggregates of the rare mineral. In general, britholite is thought to form by late-magmatic crystallization or alteration of primary minerals in alkali-rich granites (Uher et al., 2015). Its origin as an abundant phase in the Rodeo de Los Molles mineralization is one focus of this study. Lira, R., Barbieri, M., Ripley, E.M., Viñas, N.A. (1999) Actas II South

  16. Radiological safety in extraction of rare earths in India: regulatory control

    International Nuclear Information System (INIS)

    Sinha, S.; Bhattacharya, R.


    The term 'rare earths' refers to a group of f-block elements in the periodic table including those with atomic numbers 57 (Lanthanum) to 71 (Lutetium), as well as the transition metals Yttrium (39) and Scandium (21). Economically extractable concentrations of rare earths are found in minerals such as monazite, bastnaesite, cerites, xenotime etc. Of these, monazite forms the main source for rare earths in India, which along with other heavy minerals is found abundantly in the coastal beach sands. However, in addition to rare earths, monazite also contains 0.35% U 3 O 8 and 8-9% ThO 2 . Hence, extraction of rare earths involves chemical separation of the rare earths from thorium and uranium which are radioactive. The processing and extraction of rare earths from monazite therefore invariably results in occupational radiation exposure to the workers involved in these operations. In addition, in the process of removal of radioactivity from rare earths, radioactive solid waste gets generated which has 2 2 8Ra concentration in the range 2000-5000 Bq/g. Unregulated disposal of such high active waste would not only result in contamination of the soil but the radionuclides would eventually enter the food chain and lead to internal exposure of the general public. Therefore such facilities involved in recovery of rare earths from monazite attract the provisions of radiological safety regulations. Atomic Energy Regulatory Board of India has been enforcing the provisions of The Atomic Energy (Radiation Protection) Rules, 2004 and The Atomic Energy (Safe Disposal of Radioactive Waste) Rules, 1987 in these facilities. This paper shall discuss the associated radiological hazard involved in recovery of rare earths from monazite. It shall also highlight the regulatory requirements for controlling the occupational exposure of workers during design stage such as requirements on lay out of the building, ventilation, containment of radioactivity, etc and also the during operational

  17. Mianningite, (□,Pb,Ce,Na) (U{sup 4+},Mn,U{sup 6+}) Fe{sup 3+}{sub 2}(Ti,Fe{sup 3+}){sub 18}O{sub 38}, a new member of the crichtonite group from Maoniuping REE deposit, Mianning county, southwest Sichuan, China

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Xiangkun; Fan, Guang; Chen, Zhangru; Ai, Yujie [Beijing Research Institute of Uranium Geology, Beijing (China); Li, Guowu [China Univ. of Geosciences, Beijing (China). Lab. of Crystal Structure; Shen, Ganfu [Chengdu Institute of Geology and Mineral Resources, Chengdu (China)


    Mianningite (IMA 2014-072), ideally (□,Pb,Ce,Na)(U{sup 4+},Mn,U{sup 6+}) Fe{sup 3+}{sub 2}(Ti,Fe{sup 3+}){sub 18}O{sub 38}, is a new member of the crichtonite group from the Maoniuping REE deposit, Mianning county, Sichuan province, China. It was found in fractures of lamprophyre veins and in the contact between lamprophyre and a later quartz-alkali feldspar syenite dyke with REE mineralization, and is named after its type locality. Associated minerals are microcline, albite, quartz, iron-rich phlogopite, augite, muscovite, calcite, baryte, fluorite, epidote, pyrite, magnetite, hematite, galena, hydroxylapatite, titanite, ilmenite, rutile, garnet-group minerals, zircon, allanite-(Ce), monazite-(Ce), bastnaesite-(Ce), parisite-(Ce), maoniupingite-(Ce), thorite, pyrochlore-group minerals and chlorite. Mianningite occurs as opaque subhedral to euhedral tabular crystals, up to 1-2 mm in size, black in color and streak, and with a submetallic luster. Mianningite is brittle, with a conchoidal fracture. Its average micro-indentation hardness is 83.8 kg/mm{sup 2} (load 0.2 kg), which is equivalent to ∝6 on the Mohs hardness scale. Its measured and calculated densities are 4.62 (8) g/cm{sup 3} and 4.77 g/cm{sup 3}, respectively. Under reflected light, mianningite is grayish white, with no internal reflections. It appears isotropic and exhibits neither bireflectance nor pleochroism. The empirical formula, calculated on the basis of 38 O atoms per formula unit (apfu), is [□{sub 0.322}(Pb{sub 0.215}Ba{sub 0.037}Sr{sub 0.036}Ca{sub 0.010}){sub Σ0.298}(Ce{sub 0.128}La{sub 0.077}Nd{sub 0.012}){sub Σ0.217} (Na{sub 0.127}K{sub 0.036}){sub Σ0.163}]{sub Σ01.000}(U{sup 4+}{sub 0.447}Mn{sub 00.293}U{sup 6} {sup +}{sub 0.112}Y{sub 0.091}Zr{sub 0.023}Th{sub 0.011}){sub Σ0.977}(Fe{sup 3+}{sub 1.224}Fe{sup 2+}{sub 0.243}Mg{sub 0.023}P{sub 0.008}Si{sub 0.006} □{sub 0.496}){sub Σ2.000}(Ti{sub 12.464}Fe{sup 3+}{sub 5.292}V{sup 5+}{sub 0.118}Nb{sub 0.083}Al{sub 0.026}Cr{sup 3

  18. Chemical and ceramic methods toward safe storage of actinides using monazite. 1998 annual progress report

    International Nuclear Information System (INIS)

    Boatner, L.A.; Morgan, P.E.D.


    'The use of ceramic monazite, (La,Ce)PO 4 , for sequestering actinides, especially plutonium, and some other radioactive waste elements (rare earths e.g.) and thus isolating them from the environment has been championed by Lynn Boatner of ORNL. It may be used alone or, as it is compatible with many other minerals in nature, can be used in composite combinations. Natural monazite, which almost invariably contains Th and U, is often formed in hydrothermal pegmatites and is extremely water resistant--examples are known where the mineral has been washed out of rocks (becoming a placer mineral as on the beach sands of India, Australia, Brazil etc.) then reincorporated into new rocks with new crystal overgrowths and then washed out again--being 2.5--3 billion years old. During this demanding water treatment it has retained Th and U. Where very low levels of water attack have been seen (in more siliceous waters), the Th is tied up as new ThSiO 4 and remains immobile. Lest it be thought that rare-earths are rare or expensive, this is not so. In fact, the less common lanthanides such as gadolinium, samarium, europium, and terbium, are necessarily extracted and much used by, e.g., the electronics industry, leaving La and Ce as not-sufficiently-used by-products. The recent development of large scale use of Nd in Nd-B-Fe magnets has further exaggerated this. Large deposits of the parent mineral bastnaesite are present in the USA and in China. (Mineral monazite itself is not preferred due to its thorium content.) In the last 5 years it has become apparent show that monazite (more specifically La-monazite) is an unrecognized/becoming-interesting ceramic material. PuPO4 itself has the monazite structure; the PO 4 3-unit strongly stabilizes actinides and rare earths in their trivalent state. Monazite melts without decomposition (in a closed system) at 2,074 C and, being compatible with common ceramic oxides such as alumina, mullite, zirconia and YAG, is useful in oxidatively

  19. Geology and description of thorium and rare-earth deposits in the southern Bear Lodge Mountains, northeastern Wyoming (United States)

    Staatz, M.H.


    areas that total 1.69 km 2 . These deposits could be mined by open pit. The Bear Lodge disseminated deposits have one of the largest resources of both total rare earths and thorium in the United States, and although the grade of both commodities is lower than some other deposits, their large size and relative cheapness of mining make them an important future resource. Vein deposits in the Bear Lodge Mountains include all tabular bodies at least 5 cm thick. Twenty-six veins were noted in this area. These veins are thin and short; the longest vein was traced for only 137 m. Minerals vary greatly in the amount present. Gangue minerals are commonly potassium feldspar, quartz, or cristobalite intermixed with varying amounts of limonite, hematite, and various manganese oxides. Rare earths and thorium occur in the minerals monazite, brockite, and bastnaesite. Thorium content of 35 samples ranged from 0.01 to 1.2 percent, and the total rare-earth content of 21 samples from 0.23 to 9.8 percent. Indicated reserves were calculated to a depth of one-third the exposed length of the vein. Inferred reserves lie in a block surrounding indicated reserves. Indicated reserves of all veins are only 50 t of Th0 2 and 1,360 t of total rare-earth oxides; inferred reserves are 250 t of Th0 2 and 6,810 t of total rare-earth oxides. The Bear Lodge dome, which underlies the greater part of this area, is formed by multiple intrusive bodies of Tertiary age that dome up the surrounding sedimentary rocks. In the southern part of the core, the younger intrusive bodies surround and partly replace a granite of Precambrian age. This granite is approximately 2.6 b.y. old. The sedimentary rocks around the core are (from oldest to youngest): Deadwood Formation of Late Cambrian and Early Ordovician age, Whitewood Limestone of Late Ordovician age, Pahasapa Limestone of Early Mississippian age, Minnelusa Sandstone of Pennsylvanian and Early Permian age, Opeche Formation of Permian age, Minnek

  20. Fluorine (United States)

    Hayes, Timothy S.; Miller, M. Michael; Orris, Greta J.; Piatak, Nadine M.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.


    fluorine concentrations in the more evolved or differentiated igneous rocks and in hydrothermal deposits associated with those evolved igneous rocks. In sedimentary rocks, fluorine’s highest concentrations are found in phosphorites because fluorine substitutes for hydroxyl ions in apatite, which leads to fluorine concentrations of, typically, from 2 to 4 weight percent in phosphorites. Because of the presence of fluorine, phosphate fertilizer manufacturers can produce a fluorosilicic acid byproduct. Most deposits mined for fluorine are hydrothermal, however, and consist of fluorine minerals that precipitated from hot water. Magmatic brines and brines from deep within sedimentary basins that have high concentrations of dissolved fluoride are the mineralizing fluids for various types of hydrothermal fluorspar deposits. Relatively dilute hydrothermal fluids that formed in some volcanic rocks can also transport sufficient fluoride to form a high-grade fluorspar deposit. Fluorite has low solubility in a common range of hydrothermal temperatures, particularly from about 160 degrees Celsius (°C) down to 60 °C. The increasing fluorite solubility below 60 °C partly explains why some water with exceptionally high levels of dissolved fluorine are found even at ambient temperatures in evaporitic lake basins in some East African Rift valleys in Kenya and Tanzania. The geologic conditions that led to the high concentrations there are known to exist in a number of other places in the world as well, including, perhaps, places in the Basin and Range province of the United States.Eight minerals or mineral groups have sufficient fluorine in their structures to be considered as possible ores of the element; they are bastnaesite (also spelled bastnäsite; and other fluorocarbonates), cryolite, sellaite, villiaumite, fluorite, fluorapatite (in phosphorites), various phyllosilicates, and topaz. Fluorite is currently the only mineral that is mined for fluorine, and nomineral except fluorite