混合硫酸稀土晶体在MgSO_(4)-H_(2)SO_(4)-H_(2)O溶液体系溶解行为  

Dissolution Behavior of Mixed Rare Earth Sulfate Crystal in MgSO_(4)-H_(2)SO_(4)-H_(2)O Solution System

作　　者：陈世梁 王猛 孙旭 赵岩岩 冯宗玉 黄小卫 Chen Shiliang;Wang Meng;Sun Xu;Zhao Yanyan;Feng Zongyu;Huang Xiaowei(National Engineering Research Center for Rare Earth,GRINM Group Co.,Ltd.,Beijing 100088,China;General Research Institute for Nonferrous Metals,Beijing 100088,China;Hebei Province Rare Earth Functional Materials Manufacturing Innovation Center,Xiongan 071700,China)

机构地区：[1]有研科技集团有限公司稀土国家工程研究中心,北京100088 [2]北京有色金属研究总院,北京100088 [3]河北省稀土功能材料制造业创新中心,河北雄安071700

出　　处：《稀有金属》2022年第11期1460-1468,共9页Chinese Journal of Rare Metals

基　　金：国家重点研发计划项目(2020YFC1909104);广西创新驱动发展专项资金项目(桂科AA18242022)资助。

摘　　要：目前包头混合型稀土精矿主要采用硫酸法冶炼分离,该工艺处理过程中,水浸液经氧化镁中和除杂后所得净化液中稀土浓度较低,是导致该工艺硫酸镁废水量大的因素之一,而硫酸稀土晶体在此溶液体系(MgSO_(4)-H_(2)SO_(4)-H_(2)O)的溶解行为尚不明确。对此,本文以包头硫酸化焙烧稀土矿水浸液经重结晶所得混合硫酸稀土晶体为原料,研究了其在MgSO_(4)-H_(2)SO_(4)-H_(2)O体系的再溶解回收性能。考察了平衡pH、结晶产物中自由水与结晶水、研磨、硫酸镁浓度对混合硫酸稀土晶体溶解行为的影响。结果表明:阴离子种类和数量的减少及结晶体活性的降低是导致该体系下稀土溶解度降低(<30 g·L^(-1))的主要原因,增加溶液体系硫酸镁浓度是显著提升硫酸稀土晶体再回收性能的关键影响因素,当MgSO_(4)浓度(MgO计)>15 g·L^(-1)时可实现再溶解液中稀土浓度>30 g·L^(-1)。研究结果可为循环利用现行工艺产生的硫酸镁废水及开发浸出液“重结晶-再溶解”分离与回收稀土新工艺提供新思路。Baotou mixed-type rare earth(RE)ore is one of the three typical RE minerals in China and the most important light RE resource.At present,about 90%of Baotou mixed-type RE concentrate is smelted and separated by sulfuric acid method.In this sulfuric acid treatment,the total concentration of RE in the purification liquid obtained after neutralization and impurity removal by MgO is low,and the dissolution behavior of RE2(SO4)3crystal in the solution system(MgSO_(4)-H_(2)SO_(4)-H_(2)O)is not clear enough and need to be deeply studied.The mixed RE2(SO4)3crystal was obtained from Baotou sulfuric acid roasted RE concentrate as raw material through water leaching and heating crystallization.The re-solubility and recovery performance of the mixed RE sulphate crystal in MgSO_(4)-H_(2)SO_(4)-H_(2)O system were studied by the control variable method.The effects of equilibrium pH,free water and crystal water,grinding and magnesium sulfate on the dissolution behavior of mixed RE2(SO4)3crystals were investigated.The results showed that:(1)The mixed RE2(SO4)3crystal obtained from recrystallization of RE sulphate leaching solution was mainly composed of La2(SO4)3·9H_(2)O,Ce2(SO4)3·9H_(2)O and Nd2(SO4)3·2H_(2)O with a small amount of impurities such as Fe(Fe2O3,1.17%),P(P2O5,1.58%),and Ca(CaO,0.46%).The crystal could truly reflect the dissolution behavior of the mixed RE2(SO4)3crystal in the purification and removal liquid system with low ionic strength;(2)With pH of the re-dissolved solution rising from 1.0 to 1.8,the concentration of total RE(in terms of RE oxides,REO)in the dissolution solution decreased from 20 to 18 g·L^(-1),which was lower than the concentration required by industrial production of more than 30 g·L^(-1);(3)The dissolution equilibrium time of RE2(SO4)3crystal for drying to remove free water was shortened from 45 to 15 min,and the total concentration of RE in the re-dissolved solution was maintained at about 25 g·L^(-1).The total RE concentration of re-dissolved solution after roasting for removing the co

关 键 词：硫酸稀土 硫酸镁 溶解度 

分 类 号：TF845[冶金工程—有色金属冶金]