除钼渣浸出行为的热力学分析
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摘要
目前钨冶炼的主流除钼工艺是选择性沉淀法。基于钼亲硫钨亲氧的特点,硫离子优先与钼酸根反应生成硫代钼酸根,然后与铜的化合物反应生成沉淀,从而实现选择性除钼。针对这种除钼渣,基于现有的热力学数据,进行了相关的热力学计算,绘制了25℃的lgc-pH图。分析表明,钼的选择性沉淀渣在pH<10.5时才能生成, pH降低除钼效果会更好。相应的,除钼渣在较强的碱性条件下可有效浸出,随pH升高,钼所结合的硫逐渐被氧取代,形态逐渐由四硫代钼酸根向钼酸根转变:MoS■, MoOS■, MoO_2S■, MoO_3S~(2-), MoO■。而硫主要以硫离子的形态存在于溶液中。若体系中存在化学计量的铜离子,则pH>9时钼即全部以MoO■的形态进入溶液,铜以硫化物形态进入渣中。铜离子参与浸出的过程为钼的硫化过程的逆过程,称之为反硫化。反硫化浸出使除钼渣中的硫整体转变成为硫化铜渣而把硫固定下来;钼以及少量的钨成为含氧酸根离子进入溶液,有利于进一步回收。
Selective precipitation is the main process to get rid of molybdenum from tungstate solution in the tungsten industry. It is based on the character that molybdenum is sulfophile while tungsten is oxyphile, the addition of sulfur ions makes the molybdate change into thiomolybdate, and then the additive copper compounds react with them to form precipitation of copper molybdenum sludge. For this kind of sludge, based on the existing thermodynamic data, the thermodynamic calculation was carried out for the relative process. And the lgc-pH diagram of 25 ℃ was drawn. The analysis showed that the slag could be generated at pH<10.5, and the lower the pH, the better the effect of removing molybdenum. The leaching of the molybdenum slag was effective under high alkalinity. With the increase of pH, the Mo-S bonds were gradually replaced by Mo-O bond, and the morphology of molybdenum changed from tetrathiomolybdate to molybdate gradually: MoS■, MoOS■, MoO_2S■, MoO_3S~(2-), MoO■. In the presence of copper ions, when pH>9, all molybdenum were dissolved in the solution in the form of MoO■ with leaching residue as copper sulfur compounds. The leaching process copper ion involved was the reverse path of molybdenum sulfidation, which was called reverse sulfuration. In the process, sulfur was transformed into copper sulfide and fixed. Molybdenum and a small amount of tungsten were dissolved into the solution as oxyacid ions, which was favorable for further recovery.
Selective precipitation is the main process to get rid of molybdenum from tungstate solution in the tungsten industry. It is based on the character that molybdenum is sulfophile while tungsten is oxyphile, the addition of sulfur ions makes the molybdate change into thiomolybdate, and then the additive copper compounds react with them to form precipitation of copper molybdenum sludge. For this kind of sludge, based on the existing thermodynamic data, the thermodynamic calculation was carried out for the relative process. And the lgc-pH diagram of 25 ℃ was drawn. The analysis showed that the slag could be generated at pH<10.5, and the lower the pH, the better the effect of removing molybdenum. The leaching of the molybdenum slag was effective under high alkalinity. With the increase of pH, the Mo-S bonds were gradually replaced by Mo-O bond, and the morphology of molybdenum changed from tetrathiomolybdate to molybdate gradually: MoS■, MoOS■, MoO_2S■, MoO_3S~(2-), MoO■. In the presence of copper ions, when pH>9, all molybdenum were dissolved in the solution in the form of MoO■ with leaching residue as copper sulfur compounds. The leaching process copper ion involved was the reverse path of molybdenum sulfidation, which was called reverse sulfuration. In the process, sulfur was transformed into copper sulfide and fixed. Molybdenum and a small amount of tungsten were dissolved into the solution as oxyacid ions, which was favorable for further recovery.
引文
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[7] Li H G,Yang J G,Li K.Tungsten Metallurgy [M].Changsha:Central South University Press,2010.217.(李洪桂,羊建高,李昆.钨冶金学 [M].长沙:中南大学出版社,2010.217.)
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[9] Erickson B E,Helz G R.Molybdenum(VI) speciation in sulfidic waters:stability and lability of thiomolybdates [J].Geochimica et Cosmochimica Acta,2000,64(7):1149.
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[12] Osseo-Asare K.Solution chemistry of tungsten leaching systems [J].Metallurgical & Materials Transactions B,1992,21(13):555.
[13] Tytko K H,Baethe G,Cruywagen J J.Equilibrium studies of aqueous polymolybdate solutions in 1 M sodium chloride medium at 25 ℃ [J].Inorganic Chemistry,2002,24(20):3132.
[14] Sano M,Shibata J,Harada M,Nishimura S.Extraction of molybdenum and tungsten with D2EHPA and LIX63 [J].Journal of the Mining and Metallurgical Institute of Japan,1988,(104):475.
[15] Powell K J,Brown P L,Byrne,Robert H.Chemical speciation of environmentally significant metals with inorganic ligands.Part 2:the Cu2+-OH-,Cl-,CO,SO,and PO systems (IUPAC Technical Report) [J].Pure and Applied Chemistry,2007,79(5):895.
[16] Outotech.Hsc-Chemistry [CP/DK].http://www.outotec.com/products/digital-solutions/hsc-chemistry/,2006-08-10/2018-06-03.
[17] Chen A L.Study on Novel Technology and Basic Theory of Removing Copper from Nickel Sulfide Anodic Electrolyte [D].Changsha:Central South University,2006.43.(陈爱良.硫化镍电解阳极液净化除铜新工艺及其基础研究 [D].长沙:中南大学,2006.43.)
[18] Romberger S B,Barnes H L.Ore solution chemistry-(pt.) 3,solubility of CuS in sulfide solutions [J].Economic Geology,1970,(8):901.
[19] Mountain B W,Seward T M.The hydrosulphide/sulphide complexes of copper(I):experimental determination of stoichiometry and stability at 22 ℃ and reassessment of high temperature data [J].Geochimica et Cosmochimica Acta,1999,63(1):11.
[20] Fisher J F,Hall J L.Polarographic study of complexes of copper(II) ion with ammonia and various ethyl,ethanol,and ethylethanol-amines [J].Analytical Chemistry,2002,39(13):343.
[21] Zhang J L,Zhang L F.Thermodynamic equilibrium of Mo(VI)-V(V)-H2O system and its application for deep removal of vanadium from molybdate solution [J].Chinese Journal of Rare Metals,2016,40(7):701.(张家靓,张立峰.Mo(VI)-V(V)-H2O系的热力学平衡与钼酸盐深度除钒工艺的理论分析 [J].稀有金属,2016,40(7):701.)
[2] Sun M,Wang J,Jiang Y Y,Yang L F.Environmental impacts of APT copper molybdenum slag recycling process [J].Guangdong Chemical Industry,2012,39(7):145.(孙铭,王嘉,江英英,杨林峰.APT铜钼渣回收工艺过程及环境影响分析 [J].广东化工.2012,39(7):145.)
[3] Tang Z Y.New Technology of Recovering Copper and Molybdenum from Molybdenum Slag [D].Changsha:Central South University,2002.40.(唐忠阳.从除钼渣中回收铜、 钼新工艺的研究 [D].长沙:中南大学,2002.40.)
[4] Xiao C,Wu H G.Research on the technology of aged molybdenum slag treatment [J].China Molybdenum Industry,2012,36(6):25.(肖超,吴海国.陈化除钼渣处理工艺试验研究 [J].中国钼业,2012,36(6):25.)
[5] Fu W Q,Yang D J,Liu J C,Liao Y S,Mu X B.Leaching of tungsten and molybdenum from molybdenum slag [J].Hydrometallurgy of China,2015,(3):193.(付维琴,杨大锦,刘俊场,廖元双,牟兴兵.从除钼渣中浸出钨钼试验研究 [J].湿法冶金,2015,(3):193.)
[6] Gong D D,Huang Z H,Zhao L F,Xu G Z,Zhang Y.Experiments on molybdenum slag treatment technology [J].China Tungsten Industry,2015,(3):38.(龚丹丹,黄泽辉,赵立夫,徐国钻,张勇.钼渣处理工艺试验研究 [J].中国钨业,2015,(3):38.)
[7] Li H G,Yang J G,Li K.Tungsten Metallurgy [M].Changsha:Central South University Press,2010.217.(李洪桂,羊建高,李昆.钨冶金学 [M].长沙:中南大学出版社,2010.217.)
[8] Erickson B E.The Speciation of Molybdenum in Sulfidic Natural Waters [D].College Park:University of Maryland,1998.133.
[9] Erickson B E,Helz G R.Molybdenum(VI) speciation in sulfidic waters:stability and lability of thiomolybdates [J].Geochimica et Cosmochimica Acta,2000,64(7):1149.
[10] Dean J A.Lange′s Handbook of Chemistry [M].New York:McGraw-Hill,1999.687.
[11] Helz G R,Miller C V,Charnock J M,Mosselmans J F W,Pattrick R A D,Garner C D.Mechanism of molybdenum removal from the sea and its concentration in black shales:EXAFS evidence [J].Geochimica et Cosmochimica Acta,1996,60(19):3631.
[12] Osseo-Asare K.Solution chemistry of tungsten leaching systems [J].Metallurgical & Materials Transactions B,1992,21(13):555.
[13] Tytko K H,Baethe G,Cruywagen J J.Equilibrium studies of aqueous polymolybdate solutions in 1 M sodium chloride medium at 25 ℃ [J].Inorganic Chemistry,2002,24(20):3132.
[14] Sano M,Shibata J,Harada M,Nishimura S.Extraction of molybdenum and tungsten with D2EHPA and LIX63 [J].Journal of the Mining and Metallurgical Institute of Japan,1988,(104):475.
[15] Powell K J,Brown P L,Byrne,Robert H.Chemical speciation of environmentally significant metals with inorganic ligands.Part 2:the Cu2+-OH-,Cl-,CO,SO,and PO systems (IUPAC Technical Report) [J].Pure and Applied Chemistry,2007,79(5):895.
[16] Outotech.Hsc-Chemistry [CP/DK].http://www.outotec.com/products/digital-solutions/hsc-chemistry/,2006-08-10/2018-06-03.
[17] Chen A L.Study on Novel Technology and Basic Theory of Removing Copper from Nickel Sulfide Anodic Electrolyte [D].Changsha:Central South University,2006.43.(陈爱良.硫化镍电解阳极液净化除铜新工艺及其基础研究 [D].长沙:中南大学,2006.43.)
[18] Romberger S B,Barnes H L.Ore solution chemistry-(pt.) 3,solubility of CuS in sulfide solutions [J].Economic Geology,1970,(8):901.
[19] Mountain B W,Seward T M.The hydrosulphide/sulphide complexes of copper(I):experimental determination of stoichiometry and stability at 22 ℃ and reassessment of high temperature data [J].Geochimica et Cosmochimica Acta,1999,63(1):11.
[20] Fisher J F,Hall J L.Polarographic study of complexes of copper(II) ion with ammonia and various ethyl,ethanol,and ethylethanol-amines [J].Analytical Chemistry,2002,39(13):343.
[21] Zhang J L,Zhang L F.Thermodynamic equilibrium of Mo(VI)-V(V)-H2O system and its application for deep removal of vanadium from molybdate solution [J].Chinese Journal of Rare Metals,2016,40(7):701.(张家靓,张立峰.Mo(VI)-V(V)-H2O系的热力学平衡与钼酸盐深度除钒工艺的理论分析 [J].稀有金属,2016,40(7):701.)