独居石碱分解热力学研究  

Thermodynamics of alkali decomposition of monazite

作　　者：雷鑫 徐略渭 何秉轩 胡皓东 梁勇[1] LEI Xin;XU Luewei;HE Bingxuan;HU Haodong;LIANG Yong(Faculty of Materials Metallurgy and Chemistry,Jiangxi University of Science and Technology,Ganzhou 341000,China)

机构地区：[1]江西理工大学材料冶金化学学部,江西赣州341000

出　　处：《中国有色冶金》2023年第4期136-143,共8页China Nonferrous Metallurgy

基　　金：江西理工大学清江青年英才支持计划项目(JXUSTQJBJ2017004);江西省离子型稀土资源绿色开发与高值利用国家重点实验室培育计划项目(20194AFD44003)。

摘　　要：独居石是一种轻稀土含量丰富的磷酸盐稀土矿,热碱浸出法对独居石的分解率可达97%,具有较高的经济效益℃。目前关于独居石碱分解的理论相对较少,缺少对独居石中稀土元素(Ce、Pr、Nd)的转变规律研究。本文通过热力学计算,绘制了25℃与160℃温度条件下碱分解独居石RE-P-H_(2)O体系(RE为La、Ce、Pr、Nd)溶解组分lgc-pH平衡图,并利用热力学平衡相图对碱分解独居石进行分析,结果表明:25℃条件下,在所研究的pH值范围内,LaPO_(4)固相稳定存在的区域为0.08<pH<14.62,REPO_(4)(RE为Ce、Pr、Nd)固相稳定存在的区域为0<pH<14.62;当pH≥14.62时,Pr(OH)_(3)、Ce(OH)_(3)、La(OH)_(3)、Nd(OH)_(3)依次沉淀的pH值为14.62、15.06、15.24、15.46;体系温度升高至160℃后,RE(OH)_(3)初始沉淀pH值降为10.70,沉淀顺序依次为Ce(OH)_(3)、Nd(OH)_(3)、La(OH)_(3)、Pr(OH)_(3)。因此,从理论分析可知,常温常压下可以实现独居石碱分解,高温高压条件对该分解过程有明显促进作用,与现有独居石碱分解工艺相符。Monazite is a phosphate rare earth ore with abundant light rare earth content.The decomposition rate of monazite by hot alkali leaching method can reach 97%,which has high economic benefits.At present,there are relatively few theories on the alkali decomposition of monazite,and there is a lack of research on the transformation laws of rare earth elements(Ce,Pr,Nd)in monazite.This article uses thermodynamic calculations to draw the lgc-pH equilibrium diagram of the dissolved components of alkali decomposed monazite RE-P-H_(2)O system(RE is La,Ce,Pr,Nd)under temperature conditions of 25℃and 160℃.The thermodynamic equilibrium phase diagram is used to analyze alkali decomposed monazite.The results show that at 25℃,within the pH range studied,the region where LaPO_(4)solid-phase stability exists is 0.08<pH<14.62,The region where REPO_(4)(RE is Ce,Pr,Nd)solid-phase stability exists is 0<pH<14.62;When pH≥14.62,the pH values of Pr(OH)_(3),Ce(OH)_(3),La(OH)_(3),and Nd(OH)_(3)precipitated sequentially are 14.62,15.06,15.24,and 15.46;after the system temperature increased to 160℃,the initial precipitation pH of RE(OH)_(3)decreased to 10.70,and the precipitation order was Ce(OH)_(3),Nd(OH)_(3),La(OH)_(3),Pr(OH)_(3).Therefore,from theoretical analysis,it can be seen that the alkaline decomposition of solitary stones can be achieved at room temperature and pressure,and the high-temperature and high-pressure conditions have a significant promoting effect on this decomposition process,which is consistent with the existing alkaline decomposition process of solitary stones.

关 键 词：轻稀土 独居石 碱分解 沉淀反应 热力学计算 lgc-pH平衡图 

分 类 号：TF845[冶金工程—有色金属冶金] TF801.3