Improved Platinum-Group Element Extraction by NiS Fire Assay from Chromitite Ore Samples Using a Flux Containing Sodium Metaphosphate   总被引：1，自引：0，他引：1  

L. Paul Bédard  Sarah-Jane Barnes 《Geostandards and Geoanalytical Research》2004,28(2):311-316

Many chromite-rich rocks contain relatively high concentrations of the platinum-group elements (PGE). In many cases, the phases carrying PGE occur as either platinum-group minerals (PGM) or as base metal sulfides in solid solution in sulfides. In some cases, such as the UG-2 unit of the Bushveld Complex, the PGM are occluded inside chromite grains. Chromites are notably difficult to dissolve in most fluxes and if the chromite contains some PGM the possibility exists that not all the PGE will be recovered during fusion. In this work, shortcomings in published methods of analysis based on the nickel sulfide fire assay procedure were investigated and a new procedure developed based on the addition of sodium metaphosphate to the fusion mixture. Optimum composition of the fusion mixture was found to be 10 g sodium metaphosphate and 9 g silica to 10 g sample, 15 g sodium carbonate, 30 g lithium tetraborate, 7.5 g nickel and 4.5 g sulfur to achieve complete dissolution of chromite grains. The new flux mixture was evaluated by the analysis of reference material CHR-Pt+ (which is known to contain PGM inside chromite grains) and no undissolved chromite grains were found in the glassy slag. Analysis of the nickel sulfide beads from this fire assay using neutron activation analysis showed similar results for Rh and Ru when compared with published conventional true (or accepted) values, while Au, Ir, Os, Pd and Pt values determined here were 10 to 30% higher than the corresponding published conventional true values. It was concluded that the addition of sodium metaphosphate improved chromite dissolution in the flux and appears to improve PGE recovery.  相似文献   

Geochemistry of Late Cretaceous （ 60 - 67 Ma） igneous activities in the Hebrides Terrace seamount （guyot） area, Scotland     

M.El-Tokhi M.Omran A.E-Muslem 《中国地球化学学报》2005,24(1):9-17

Tholeiitic basalts in various stages of alteration were dredged from Late Cretaceous volcanic rocks (60 -67 Ma) in the Hebrides Terrace seamount area in the Atlantic Ocean. These rocks are extrusive olivine basalts, including high- and low-Al basalts. High-Al basalts are depleted in MgO, CaO, Cr,Sc, V, St, Zr and enriched in TiO2, Na2O, Nb, Rb as compared with low-A1 basalts. Petrography and bulk-rock composition (major, trace and rare-earth elements) data defined clear tholeiitic suites displaying possible liquid lines of descent related to different degrees of crystal fractionation and partial melting.Isotopic dating of dredged samples gave the guyot an age of 60 - 67 Ma, in support of the assumption that it was formed during the Late Cretaceous.  相似文献   

Experimental determination of argon solubility in silicate melts: An assessment of the effects of liquid composition and temperature     

Y. Marrocchi  M.J. Toplis 《Geochimica et cosmochimica acta》2005,69(24):5765-5776

The argon solubility of 38 liquids in the system Na₂O-CaO-MgO-Al₂O₃-SiO₂ (NCMAS) has been determined at 1873 K and 1 bar, the argon concentration of presaturated glasses being measured using a static mass spectrometer. For compositions in the subsystem diopside (CaMgSi₂O₆), nepheline (NaAlSiO₄), albite (NaAlSi₃O₈), anorthite (CaAl₂Si₂O₈), argon solubility is generally a linear function of the relative proportion of each end member, solubility being lowest in diopside melt (1.53 10⁻⁵ cm³ STP · g⁻¹ · bar⁻¹) and highest in albite melt (2.88 10⁻⁴ cm³ STP · g⁻¹ · bar⁻¹). For the tectosilicate joins studied (SiO₂-Na₂Al₂O₄, SiO₂-CaAl₂O₄, SiO₂-MgAl₂O₄) solubility decreases with decreasing silica content in all cases, being highest for Na-bearing liquids and lowest for Mg-bearing liquids at constant molar silica content. Where comparison is possible our results are in good agreement with data from the literature. When our data are considered in isolation we find that argon solubility shows an excellent correlation with calculated ionic porosity. The covariation of argon solubility and liquid density is also reasonable, that with molar volume less convincing and that with polymerization state (as defined by the ratio of the number of nonbridging oxygens and tetrahedral network forming cations; NBO/T) nonexistent. However, when our data are combined with those from the literature no well constrained correlation between argon solubility and ionic porosity is apparent. Based upon this observation and consideration of the temperature dependence of noble gas solubility it is concluded that ionic porosity is not a universally applicable parameter which may be used to predict noble gas solubility as a function of composition, temperature and pressure. Two new models for calculating argon solubility are proposed, both employing the notion of partial molar argon solubilities. The first uses oxide components, for which partial molar argon solubility is directly proportional to partial molar ionic porosity calculated at 1873 K, irrespective of the temperature of experimental equilibration. The second model, which offers the best fit to the available data, employs tetrahedral units rather than oxides as the proposed melt components. This latter model successfully accounts for reported argon solubilities in simple Al-free systems, in simple Al-bearing systems and in natural liquids. This is interpreted to infer that argon is incorporated in large sites in the liquid structure (such as the space within rings of n-tetrahedra) although further work is required to understand the quantitative links between melt structure and noble gas solubility.  相似文献   

高效液相色谱-电感耦合等离子体质谱联用检测土壤中的无机硒形态   总被引：3，自引：3，他引：0  

秦冲  施畅  万秋月  王磊  刘爱琴  安彩秀 《岩矿测试》2018,37(6):664-670

土壤样品中亚硒酸盐Se(Ⅳ)和硒酸盐Se(Ⅵ)的形态分析中,提取剂的选择和检测方法是技术的关键。以往的提取剂容易导致硒形态发生转变或无法同时提取Se(Ⅳ)和Se(Ⅵ),常用的氢化物发生原子荧光光谱法无法直接测定Se(Ⅵ),而是通过差减法得出Se(Ⅵ)含量。本文对比了不同提取剂的提取能力,确定使用0. 1 mol/L氢氧化钠溶液作为提取剂,在55℃超声萃取土壤样品30 min,提取液经高效液相色谱分离,电感耦合等离子体质谱检测,建立了土壤中Se(Ⅳ)和Se(Ⅵ)的形态分析方法。采用Hamilton PRP X-100色谱柱,以6 mmol/L柠檬酸为流动相,pH=5. 5,在8 min内可完全分离Se(Ⅳ)和Se(Ⅵ),两者的检出限分别为0. 15μg/L、0. 16μg/L,线性相关系数(r~2)均大于0. 999。以土壤为基体进行加标回收试验,Se(Ⅳ)和Se(Ⅵ)的回收率在84. 2%～95. 8%之间,相对标准偏差为1. 4%～5. 3%(n=6)。该方法简单快速,具有良好的精密度和准确度,适用于土壤中无机硒的形态分析。  相似文献   

钙同位素地球化学研究新进展及其在碳酸岩-共生硅酸盐研究中的应用     

向蜜  龚迎莉  刘涛  田世洪 《地质学报》2021,95(12):3937-3960

作为"非传统稳定同位素"家族成员,钙同位素正受到国际地学界日益广泛的关注.钙是主要的造岩元素,也是生物必需的元素.钙在地球各圈层广泛分布,研究钙同位素的地球化学行为将有助于提高我们对各种生物过程和地质过程的认识.钙同位素测定主要采用热电离质谱仪(TIMS)和多接收电感耦合等离子体质谱仪(MC-ICP-MS),分别表示为δ44/40 Ca和δ44/42Ca.目前自然界可观测到的δ44/40Ca变化范围为-2.0‰～6.75‰,约8.7‰.本文系统介绍了近年来钙同位素分析中样品溶解、化学分离、质谱测定以及高温地质过程中的钙同位素分馏及其地质应用等方面的研究成果,尤其对钙同位素在碳酸岩-共生硅酸盐岩研究中的意义、钙同位素组成以及取得的主要认识作了较为全面的介绍.阐述了放射成因40 Ca、部分熔融作用/分离结晶作用、地壳同化作用、古俯冲碳酸盐循环、热液蚀变作用、岩浆起源深度等对碳酸岩、硅酸盐岩的钙同位素组成造成的影响.最后,通过系统对比碳酸岩-共生硅酸盐岩的锂、镁、钙同位素研究成果,认为应该开展多元同位素体系的联合示踪.由于不同同位素体系存在相似性和差异性,而多元同位索体系相结合能有效地加强优势互补,将是同位素地球化学研究发展的一种必然趋势.  相似文献   

Petrogenesis and sedimentary environment of silicate in Late Paleozoic in Kala area of Western Sichuan Province     

LIU Daming  YAO Hongyou  HU Lin  YU Liang  LIU Yizhong 《中国地质调查》2021,7(6):68-78

In order to study the sedimentary environment characteristics of the Late Paleozoic in Kala area of Western Sichuan Province, the authors have conducted the petrological and geochemical analyses of the widely distributed silicate in Qiongyi Formation of Lower Carboniferous and Kawenggou Formation of Upper Permian. The results show that the silicate in the study area belongs to the pure siliceous rocks, with a continuous supply of land-based materials during the deposition process. The average Al/(Al+Fe+Mn) ratio is 0.62, and the silicate shows a biogenic origin by the Al-Fe-Mn diagram. The ratios of Al₂O₃/ (Al₂O₃+ Fe₂O₃), Th/U, Th/Sc, (La/Ce)_N and (La/Yb)_N and tectonic environment discriminant diagram demonstrate that the silicate developed in a shallow-slope depesitional environment in the continental margin. The Ce_anom value is -0.04 to 0.07, and it gradually increases from the Carboniferous to the Permian period, indicating the water body is in an anoxic environment with gradually increasing reducibility. The Garz--Litang basin opened in the Carboniferous period, in accordance with the regional geological evolution, and it continued to expand during the Permian period, with the gradually increasing depth of the seawater within the sedimentary basins.  相似文献   

Application of a Bayesian model to infer the contribution of coalbed natural gas produced water to the Powder River,Wyoming and Montana          下载免费PDF全文

Jason M. Mailloux  Kiona Ogle  Carol D. Frost 《水文研究》2014,28(4):2361-2381

The Powder River Basin (PRB) of Wyoming and Montana contains significant coal and coal bed natural gas (CBNG) resources. CBNG extraction requires the production of large volumes of water, much of which is discharged into existing drainages. Compared to surface waters, the CBNG produced water is high in sodium relative to calcium and magnesium, elevating the sodium adsorption ratio (SAR). To mitigate the possible impact this produced water may have on the quality of surface water used for irrigation, the State of Montana passed water anti‐degradation legislation, which could affect CBNG production in Wyoming. In this study, we sought to determine the proportion of CBNG produced water discharged to tributaries that reaches the Powder River by implementing a four end‐member mixing model within a Bayesian statistical framework. The model accounts for the ⁸⁷Sr/⁸⁶Sr, δ¹³C_DIC, [Sr] and [DIC] of CBNG produced water and surface water interacting with the three primary lithologies exposed in the PRB. The model estimates the relative contribution of the end members to the river water, while incorporating uncertainty associated with measurement and process error. Model results confirm that both of the tributaries associated with high CBNG activity are mostly composed of CBNG produced water (70–100%). The model indicates that up to 50% of the Powder River is composed of CBNG produced water downstream from the CBNG tributaries, decreasing with distance by dilution from non‐CBNG impacted tributaries from the point sources to ~10–20% at the Montana border. This amount of CBNG produced water does not significantly affect the SAR or electrical conductivity of the Powder River in Montana. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

沁县七星泉天然矿泉水水质特征     

李荣生 《华北地质矿产杂志》1994,9(4):405-410

沁县七星泉（后泉）饮用天然矿泉水是山西发现最早的天然矿泉水之一。１９８７年１１月经国家级鉴定为低钠、低矿化度、锶重碳酸－钙镁型饮用天然矿泉水。可作为瓶装天然矿泉水及矿泉饮料用水予以开发。  相似文献   

锰矿石中硅酸锰的分离和测定方法对比     

耿学道  李维翰 《岩矿测试》1994,13(1):49-51

文章对几种分离测量硅酸锰的方法进行了对比。指出硅酸锰测定失真的缘由。选择了浸取分离伴生铁矿物的浸取剂及浸取分离条件。  相似文献   

Biological and physical events involved in the origin,effects, and control of organic matter in solar saltworks     

Joseph S. Davis  Mario Giordano 《International Journal of Salt Lake Research》1995,4(4):335-347

Aspects of communities and events in the concentrating ponds (S.G. 1.130 to 1.214) and salt crystallizing ponds (S.G. 1.215 to 1.264) of solar saltworks pertinent to salt manufacture are described. Communities that aid salt manufacture enable continuous and efficient production of high quality salt at a saltworks' design capacity, and they provide important controls on levels of organic matter in the brine. Fluctuating salinities, high concentrations of nutrients, and petroleum products are disturbances that causeAphanothece halophytica andDunaliella salina to release excessive quantities of organic matter, and that suppress or cause death to nutrient stripping organisms. Disturbances result in decreased quality and quantity of salt and increased costs for salt harvest, washing, and pond upkeep. Organic matter can be controlled by management techniques that keep nutrient stripping communities at proper levels and maintain a narrow and unchanging range of salinities in each pond, by constructing pond dikes able to withstand wind and water erosion, and by preventing spills of petroleum products in the ponds.  相似文献