碱性萃取分离钨铝过程的热力学分析  

Mechanisms Research on W/Al Separation by Direct Extraction of Tungstate under Alkali Conditions

作　　者：肖超[1] 曾理 韦建华 肖连生 Xiao Chao;Zeng Li;Wei Jianghua;Xiao Liansheng(Guangxi Key Laboratory in Universities of Clean Metallurgy and Comprehensive Utilization for Non-Ferrous Metals Re- sources, Faculty of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, China;School of Metallurgy and Environment, Central South University, Changsha 410083, China)

机构地区：[1]桂林理工大学材料科学与工程学院、广西高校有色金属清洁冶炼与综合利用重点实验室,广西桂林541004 [2]中南大学冶金与环境学院,湖南长沙410083

出　　处：《稀有金属》2018年第3期291-298,共8页Chinese Journal of Rare Metals

基　　金：广西高校有色金属清洁冶炼与综合利用重点实验室开放基金项目(2016ZZKT-08);国家自然科学基金项目(51741403)资助

摘　　要：针对碱性萃取分离钨、铝过程,根据同时平衡和物质守恒定律,应用现有的热力学数据绘制了25℃时W/Al-H2O系的溶解组分浓度-pH图,Na2CO3-NaHCO3-H2O系R-pH图（R为萃取剂中（R4N）2CO3与（R4N）2CO3＋R4NHCO3物质量比例）,利用热力学平衡图对碱性萃取钨铝分离过程进行研究。结果表明：[W]T,[Al]T分别为0.5,0.1 mol·L-1,溶液pH为11.5~14.0时钨、铝分别以WO42-,Al（OH）-4存在;pH为4.0~11.5时铝部分以Al（OH）3（am）沉淀析出,钨以阴离子形态存在溶液中;Na2CO3-NaHCO3-H2O系中,NaHCO3含量增加,溶液pH值降低。试验表明,Al（OH）-4能与季铵盐形成萃合物存在有机相中,不会出现沉淀或影响萃取;季铵盐对WO42-的结合能力强于Al（OH）-4;碳酸氢型萃取剂参与钨萃取反应降低萃余液溶液pH值,萃余液pH值低于11.46时铝水解产生氢氧化铝沉淀。串级试验表明,控制萃余液pH为11.59,通过12级逆流萃取,钨、铝的萃取率分别为99.17%,1.20%,说明碱性萃取工艺能够高效地分离钨铝。According to the laws of simultaneous equilibria and mass conservation,the concentration-pH diagram of W/Al-H2O system and the R-pH diagram（R means mole ratio of（R4 N）2 CO3 to（R4 N）2 CO3＋ R4 NHCO3 in the system） of Na2CO3-NaHCO3-H2O system were established on the basis of thermodynamic data at 25 ℃. Thermodynamic analysis was carried out to show the effect of technical conditions on W/Al separation by direct extraction of tungstate under alkali conditions. The results showed that with pH value of 11. 5 ~ 14. 0,tungsten,aluminum existed as WO4^（2-）,Al（OH）-4,respectively. When pH value was 4. 0 ~ 11. 5,tungsten,aluminum existed as anion and aluminum hydroxide precipitation,respectively. W content was 0. 5 mol·L-1,while Al content was 0.1 mol·L-1 in the system. The pH value decreased with the increase of NaHCO3 concentration of the Na2CO3-NaHCO3-H2O system. The verification experiment results showed that Al（OH）-4 could keep stable in quaternary ammonium salt organic phase,and did not form precipitate or deteriorate phase separation. WO42- was extracted preferentially by quaternary ammonium salt for a sodium tungstate and sodium aluminate solution. The pH value of raffinate decreased since bicarbonate type extractant extracted WO42- for a sodium carbonate solution with W and Al. When the pH was a little lower than 11. 46,aluminum hydroxide sediment was created by aluminate hydrolyzing.The results showed that with the raffinate pH of 11. 59,after 12-stage counter current extraction,extraction rate of tungsten and aluminum reached 99. 17%,1. 20%,respectively. Which showed alkaline extraction technology could achieve high efficient separation of tungsten aluminum.

关 键 词：钨 铝 溶剂萃取 分离 季铵盐 

分 类 号：TF841.1[冶金工程—有色金属冶金]