Comprehensive recovery of rare earth elements and gypsum from phosphogypsum:A wastewater free process combining gravity separation and hydrometallurgy  

作　　者：Jialin Qing Dapeng Zhao Li Zeng Guiqing Zhang Liang Zhou Jiawei Du Qinggang Li Zuoying Cao Shengxi Wu 

机构地区：[1]School of Metallurgy and Environment,Central South University,Changsha,410083,China [2]Key Laboratory of Metallurgical Separation Science and Engineering of Non-ferrous Metals Industry,Central South University,Changsha,410083,China [3]National Engineering Laboratory for Efficient Utilization of Refractory Non-ferrous Metals Resources,Central South University,Changsha,410083,China

出　　处：《Journal of Rare Earths》2025年第2期362-370,I0005,共10页稀土学报(英文版)

基　　金：Project supported by the National Natural Science Foundation of China(52104354);the National Natural Science Foundation of China(51674036);Joint Fund for Nuclear Technology Innovation Sponsored by the National Natural Science Foundation of China;the China National Nuclear Corporation(U2067201)。

摘　　要：Comprehensive utilization of phosphogypsum(PG)has attracted much attention,especially for the recovery of rare earth elements(REEs)and gypsum due to the issues of stockpile,environmental pollution,and waste of associated resources.Traditional utilization methods suffered the issues of low REEs leaching efficiency,huge amount of CaSO_(4)saturated wastewater and high recovery cost.To solve these issues,this study investigated the occurrence of REEs in PG and the leaching of REEs.The results show that REEs in PG are in the forms of(1)REEs mineral inclusions,(2)REEs isomorphous substitution of Ca^(2+)in gypsum lattice,(3)dispersed soluble REEs salts.Acid leaching results demonstrate that(1)the dissolution of gypsum matrix is the control factor of REEs leaching;(2)H_(2)SO_(4)is a promising leachant considering the recycle of leachate;(3)the gypsum matrix suffers a recrystallization during the acid leaching and releases the soluble REEs from PG to aqueous solution.For the recovery of the undissolved REEs mineral inclusions,wet sieving concentrated 37.1 wt%of the REEs in a 10.7 wt%mass,increasing REEs content from 309 to 1071 ppm.Finally,a green process combining gravity separation and hydrometallurgy is proposed.This process owns the merits of wastewater free,considerable REEs recovery(about 10%increase compared with traditional processes),excellent gypsum purification(>95 wt%CaSO_(4)·2H_(2)O,with<0.06 wt%of soluble P_(2)O_(5) and<0.015 wt%of soluble F)and reagent saving(about 2/3less reagent consumption than non-cyclical leaching).

关 键 词：PHOSPHOGYPSUM Rare earths Wastewater free Recrystallization reinforcement Gravity separation 

分 类 号：TF845[冶金工程—有色金属冶金]