Mo(Ⅵ)-V(Ⅴ)-H_2O体系的热力学分析
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摘要
通过热力学计算,绘制Mo(Ⅵ)-V(Ⅴ)-H_2O体系中不同Mo,V浓度下各物质随p H值变化的平衡图(25℃),为现行的钼钒分离技术提供理论依据。对计算结果分析可知,碱性溶液中Mo元素以单钼酸根形式存在,而V元素在弱碱性条件下即聚合为同多钒酸根。由于聚合阴离子与吸附剂的结合能力通常强于单核阴离子,故可从p H=7~8的溶液中实现Mo,V有效分离。当溶液p H值降至中性时,单钼酸根开始聚合成同多钼酸根;而p H值降至弱酸性时,同多钒酸根和同多钼酸根转变成多种钼钒杂多酸根。由于p H=6.5~7的溶液中杂多酸根的比例较少,添加试剂促进杂多酸根的解聚有助于钼钒的分离;p H=2~6的溶液中两者难以分离的原因在于杂多酸根的比例很大。
The thermodynamic equilibrium diagrams of Mo(Ⅵ)-V(Ⅴ)-H_2 O system on the distribution of substances at different p H and concentrations of Mo and V at 25 ℃ were drawn to provide theoretical explanation for the current separation technology of them. It is shown that Mo exists as single molybdate in alkaline solution, while V can be aggregate into isopoly vanadates in weak alkaline conditions. The binding power of polymeric anions and adsorbents is usually better than that of single anions and adsorbents, so the effective separation of Mo and V can be achieved in the p H=7~8 aqueous solution. When the p H is lowered to neutral, single molybdate begin to aggregate into isopoly molybdates; as the p H value is lowered to weak acid, isopoly molybdates and isopoly vanadates transform into a variety of heteropolyanions. Because the ratio of heteropolyanions is little in p H=6.5~7 solution, the addition of reagents which can promote the depolymerization of heteropolyanions may contribute to the separation. However, it is difficult to separate Mo and V in the p H=2~6 solutions, owing to a large proportion of heteropolyanions.
The thermodynamic equilibrium diagrams of Mo(Ⅵ)-V(Ⅴ)-H_2 O system on the distribution of substances at different p H and concentrations of Mo and V at 25 ℃ were drawn to provide theoretical explanation for the current separation technology of them. It is shown that Mo exists as single molybdate in alkaline solution, while V can be aggregate into isopoly vanadates in weak alkaline conditions. The binding power of polymeric anions and adsorbents is usually better than that of single anions and adsorbents, so the effective separation of Mo and V can be achieved in the p H=7~8 aqueous solution. When the p H is lowered to neutral, single molybdate begin to aggregate into isopoly molybdates; as the p H value is lowered to weak acid, isopoly molybdates and isopoly vanadates transform into a variety of heteropolyanions. Because the ratio of heteropolyanions is little in p H=6.5~7 solution, the addition of reagents which can promote the depolymerization of heteropolyanions may contribute to the separation. However, it is difficult to separate Mo and V in the p H=2~6 solutions, owing to a large proportion of heteropolyanions.
引文
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[21]ZHANG P,INOUE K,TSUYAMA H.Recovery of metal values from spent hydrodesulfurization catalysts by liquid-liquid extraction[J].Energy&Fuels,1995,9(2):231-239.
[22]ZHANG P,INOUE K,YOSHIZUKA K,et al.Extraction and selective stripping of molybdenum(Ⅵ)and vanadium(Ⅳ)from sulfuric acid solution containing aluminum(Ⅲ),cobalt(Ⅱ),nickel(Ⅱ)and iron(Ⅲ)by LIX 63 in Exxsol D80[J].Hydrometallurgy,1996,41(1):45-53.
[2]ZHAO Z,YANG L,HUO G,et al.Solvent extraction of molybdenum blue from alkaline leaching solution of the Ni-Mo ore[J].International Journal of Refractory Metals and Hard Materials,2011,29(2):232-236.
[3]HOU X,XIAO L,GAO C,et al.Kinetics of leaching selenium from Ni-Mo ore smelter dust using sodium chlorate in a mixture of hydrochloric and sulfuric acids[J].Hydrometallurgy,2010,104(1):76-80.
[4]ZENG L,CHENG C Y.Recovery of molybdenum and vanadium from synthetic sulphuric acid leach solutions of spent hydrodesulphurisation catalysts using solvent extraction[J].Hydrometallurgy,2010,101(3/4):141-147.
[5]ZHU Z,TULPATOWICZ K,PRANOLO Y,et al.Solvent extraction of molybdenum and vanadium from sulphate solutions with Cyphos IL 101[J].Hydrometallurgy,2015,154(1):72-77.
[6]NGUYEN T H,LEE M S.Separation of molybdenum and vanadium from acid solutions by ion exchange[J].Hydrometallurgy,2013,136(1):65-70.
[7]SAHU K K,AGRAWAL A,MISHRA D.Hazardous waste to materials recovery of molybdenum and vanadium from acidic leach liquor of spent hydroprocessing catalyst using alamine 308[J].Journal of Environmental Management,2013,125(1):68-73.
[8]WANG X,WANG M,SHI L,et al.Recovery of vanadium during ammonium molybdate production using ion exchange[J].Hydrometallurgy,2010,104(2):317-321.
[9]ROJAS-RODR GUEZ A D,FLORES-FAJARDO O,GONZ LEZ F S A,et al.Chemical treatment to recover molybdenum and vanadium from spent heavy gasoil hydrodesulfurization catalyst[J].Advances in Chemical Engineering and Science,2012,2(3):408-412.
[10]MISHRA D,CHAUDHURY G R,KIM D J,et al.Recovery of metal values from spent petroleum catalyst using leachingsolvent extraction technique[J].Hydrometallurgy,2010,101(1/2):35-40.
[11]LI X,WEI C,WU J,et al.Co-extraction and selective stripping of vavadium(Ⅳ)and molybdenum(Ⅵ)from sulfuric acid solution using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester[J].Separation and Purification Technology,2012,86(1):64-69.
[12]CRUYWAGEN J J.Protonation,oligomerization,and condensation reactions of vanadate(Ⅴ),molybdate(Ⅵ),and tungstate(Ⅵ)[J].Advances in Inorganic Chemistry,1999,49(1):127-182.
[13]张家靓,赵中伟.W(Ⅵ)-V(Ⅴ)-H2O体系钨钒分离的热力学分析[J].中国有色金属学报,2014,24(6):1656-1662.ZHANG Jialiang,ZHAO Zhongwei.Thermodynamic analysis for separation of tungsten and vanadium in W(Ⅵ)-V(Ⅴ)-H2O system[J].The Chinese Journal of Nonferrous Metals,2014,24(6):1656-1662.
[14]TYTKO K,BAETHE G,CRUYWAGEN J.Equilibrium studies of aqueous polymolybdate solutions in 1 M sodium chloride medium at 25℃[J].Inorganic Chemistry,1985,24(20):3132-3136.
[15]SANO M,SHIBATA J,HARADA M,et al.Extraction of molybdenum and tungsten with D2EHPA and LIX 63[J].J Min Metall Inst Jpn,1988,104(1205):475-479.
[16]HOWARTH O W,PETTERSSON L,ANDERSSON I.Aqueous molybdovanadates at high Mo:V ratio[J].Journal of the Chemical Society,Dalton Transactions,1991(7):1799-1812.
[17]曾理.酸性溶液中钼、钒、镍、钴的提取与分离研究[D].长沙:中南大学,2011:15-20.ZENG Li.Extraction and separation of molybdenum,vanadium,nickel,cobalt from acid leach solution[D].Changsha:Central South University,2011:15-20.
[18]张正斌,顾宏勘,刘莲生.海洋化学[M].上册.上海:上海科学技术出版社,1984:107-113.ZHANG Zhengbin,GU Hongkan,LIU Liansheng.Ocean Chemistry[M].Volume I.Shanghai:Shanghai Science and Technology Press,1984:107-113.
[19]БH拉斯科林.湿法冶金:加压浸出、吸附、萃取[M].张镛,夏润身,蒋铮民,译.北京:原子能出版社,1984:139-144.LAS COLINAS B H.Hydrometallurgy:Pressure Leaching,Adsorption,Extraction[M].ZHANG Yong,XIA Runsheng,JIANG Zhengmin,translate.Beijing:Atomic Energy Press,1984:139-144.
[20]曾理,肖连生,李青刚,等.离子交换法从钼酸铵溶液中分离钼钒的研究[J].稀有金属与硬质合金,2006,34(2):1-4.ZENG Li,XIAO Liansheng,LI Qinggang,et al.Study of separation of vanadium from ammonium molybdate solution by ion exchange[J].Rare Metals and Cemented Carbides,2006,34(2):1-4.
[21]ZHANG P,INOUE K,TSUYAMA H.Recovery of metal values from spent hydrodesulfurization catalysts by liquid-liquid extraction[J].Energy&Fuels,1995,9(2):231-239.
[22]ZHANG P,INOUE K,YOSHIZUKA K,et al.Extraction and selective stripping of molybdenum(Ⅵ)and vanadium(Ⅳ)from sulfuric acid solution containing aluminum(Ⅲ),cobalt(Ⅱ),nickel(Ⅱ)and iron(Ⅲ)by LIX 63 in Exxsol D80[J].Hydrometallurgy,1996,41(1):45-53.