摘要
四川甲基卡、李家沟等地锂辉石储量丰富,为下游锂电池储能材料等领域提供了重要的原料来源。传统锂辉石制碳酸锂工艺中,采用氢氧化钠中和法除去铁、铝等杂质,但是副产硫酸钠附加值低,导致生产成本较高,本论文研究了以氨气替代强氧化钠中和法除杂制碳酸锂工艺,发现在精制锂溶液沉淀结晶过程中存在LiNH_(4)SO_(4)复盐产生,影响了锂的收率和碳酸锂产品品质。为解决此问题,本论文采用等温溶解平衡法研究了三元体系Li^(+),NH_(4)^(+)∥SO_(4)^(2-)-H_(2)O在298 K下的稳定相平衡关系,测定了平衡液相中各组分溶解度、密度和折光率数据,并绘制了该体系的相图、密度-组成图和折光率-组成图。结果表明该三元体系为复杂三元体系,有复盐LiNH_(4)SO_(4)形成;其稳定相图由3个固相结晶区,3条单变量曲线和2个共饱点组成,3个结晶区分别为(NH_(4))_(2)SO_(4),Li_(2)SO_(4)·H_(2)O和LiNH_(4)SO_(4),且LiNH_(4)SO_(4)复盐的结晶区较大。研究结果表明,为了避免LiNH_(4)SO_(4)复盐的产生,需在锂辉石制工业级碳酸锂工艺前端通过钙离子沉淀法将锂溶液中锂硫比[Li_(2)SO_(4)·H_(2)O/(NH4)2SO4]降到1.6以下,研究结果为四川锂辉石湿法冶金工艺中采用氨中和除杂提供了理论指导。
Sichuan Jiajika,Lijiagou and other places have rich spodumene reserves,it provides an important source of raw materials for downstream lithium battery energy storage materials and other fields.In the traditional spodumene production process of lithium carbonate,sodium hydroxide neutralization method is used to remove impurities such as iron and aluminum.However,the added value of by-product sodium sulfate is low,resulting in high production costs.This paper studies the process of replacing strong sodium oxide with ammonia gas to neutralize impurities to prepare lithium carbonate,it was found that LiNH_(4)SO_(4)double salt was produced during the precipitation and crystallization process of refined lithium solution,which affected the yield of lithium and the quality of lithium carbonate products.In order to solve the problem,the stable phase equilibrium relationship of the ternary system Li^(+),NH_(4)^(+)∥SO_(4)^(2-)-H_(2)O at 298 K was studied by the isothermal dissolved equilibrium method.The solubility,density and refractive index data of each component of the equilibrium liquid phase were measured,and the phase diagram,density-composition diagram and refractive index composition diagram of the system were drawn.The results show that this system is a complex ternary system,with the formation of LiNH_(4)SO_(4)double salt;its stable phase diagram consists of 3 solid phase crystallization regions,3 univariate curves,2 invariant points,3 crystallization regions corresponding to(NH_(4))_(2)SO_(4),Li_(2)SO_(4)·H_(2)O and LiNH_(4)SO_(4),And double salt LiNH_(4)SO_(4)crystallization area is the largest.The research results show that in order to avoid the production of LiNH_(4)SO_(4)double salt,It is necessary to reduce the lithium-sulfur ratio(w(Li_(2)SO_(4))·H_(2)O/w(NH_(4))_(2)SO_(4))in the lithium solution to less than 1 through the calcium ion precipitation method at the front end of the spodumene-made industrial-grade lithium carbonate process,the research results provide theoretical guidance for the use of am
作者
程籽毅
魏卓
何智妍
肖淑云
王彦旭
周堃
CHENG Ziyi;WEI Zhuo;HE Zhiyan;XIAO Shuyun;WANG Yanxu;ZHOU Kun(College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059, China)
出处
《矿产保护与利用》
2021年第1期141-145,共5页
Conservation and Utilization of Mineral Resources
基金
四川省科技厅重点研发项目-四川锂辉石制工业级碳酸锂新工艺技术开发(2019YFG0133)。
关键词
硫酸锂
硫酸铵
相平衡
硫酸氨锂复盐
lithium sulfate
ammonium sulfate
phase equilibrium
lithium ammonium sulfate double salt
