独居石中铀铁钍稀土萃取分离的研究

EXTRACTION-SEPARATION PROCESS FOR U,Fe,Th AND RARE EARTH ELEMENTS IN MONAZITE

本文详细介绍了从独居石铀钍渣盐酸全溶的溶液中回收铀、钍和稀土的工艺.成功地研究出在1.5—2.0mol/L 盐酸介质中用20%DMHMP-5%TBP-煤油溶液有效地萃取铀、铁,与钍、稀土分离.萃取剂浓度和料液中盐酸浓度等是影响铀、铁萃取的主要因素.在研究中首次发现了在萃取铀、铁后含钍、稀土的盐酸介质中直接添加适量硝酸,用20%—40%DMHMP-煤油溶液能选择性地萃取钍,从而有效地与稀土分离.详细研究了 DMHMP、TBP 在盐酸-硝酸混合酸介质中的萃钍性能及其影响因素.同时对萃取铀、铁、钍后的水相,用 DMHMP、TBP 进行了苯取残留硝酸的比较研究.该研究成果已用于广东德庆稀土冶炼厂并投入生产,大量制备出符合国家标准的纱罩级硝酸钍和一级重铀酸铵.

The recovery process for U,Th,and RE from monazite U,Th resi- due hydrochloric acid solution is described in detail.When 20% DMHMP-5% TBP- kerosene is taken as the extractant in 1.5—2.0 mol/L HCl medium,U,Fe can be ex- tracted effectively so as to be separated from Th and RE.The concentrations of the extractant and HCl are the main factors influencing U,Fe extraction.For the first time,it is discovered that:after U,Fe are stripped,Th can be extracted selectively by means of adding proper amount of nitric acid directly into the HCl medium contain- ing Th and RE,and by using 20%—40% DMHMP-kerosene as extractant,which results in an effective separation of Th from RE.The properties of DMHMP and TBP in extracting Th in the mixed HCl-HNO_3 acid and their affecting factors are studied in detail.By use of DMHMP or TBP,a comparison research has been made for ex- tracting the HNO_3 raffinate in the water-phase formed after U,Fe,Th being extracted. This process has been put into operation by Deqing Smelter for Rare Earths,Guang- dong Province.A large amount of ammonium diuranate and thorium nitrate are pro- duced.Both of them have come up to the first grade by national standard,the technical requirement of mentle-grade,respectively.