摘要
风化壳淋积型稀土矿的开采主要通过浸矿剂离子与吸附在黏土矿物表面的稀土离子发生离子交换浸出反应实现。以(NH_(4))_(2)SO_(4)为浸矿剂,采用多级逆流浸取的方式研究了风化壳淋积型稀土矿的浸矿过程,通过在逐级浸取过程中浸出液组分的变化分析了矿土中稀土离子(RE^(3+))和主要杂质铝离子(Al^(3+))的浸出行为,并基于浸矿剂的消耗规律探讨了浸矿剂离子与RE^(3+)和Al^(3+)的离子交换反应机制以及原矿土的净吸附量。结果表明,在浸矿液逐级浸取新鲜矿土的过程中,浸出液中的RE^(3+)和Al^(3+)浓度逐渐增加,铵根离子(NH_(4)^(+))逐渐消耗,交换进入浸出液中的RE^(3+)和Al^(3+)逐级减少;同时,浸出液中的硫酸根离子(SO_(4)^(2-))逐级损耗,说明新鲜矿土除因发生离子交换反应消耗NH_(4)^(+)外,还存在对浸矿剂的净吸附,经计算,本实验原矿土中吸附稀土、吸附铝及净吸附的位点之比约为20∶41∶39。在两轮逆流浸取实验中,Al^(3+)在浸出液中的浸出规律始终与RE^(3+)类似,未表现出与浸出液p H变化(由4.5降低至4.0)的相关性。另外,分析显示,在浸矿反应的p H条件下,RE^(3+)为稀土的主要存在形态,而Al^(3+),Al OH^(2+),Al(OH)_(2)^(+)为铝的主要存在形态,结合物料关系推知NH_(4)^(+)与稀土发生离子交换反应的化学计量比应接近或等于3∶1,而NH_(4)^(+)与铝发生离子交换反应的化学计量比约为1.8∶1。
The leaching of weathered crust elution-deposited rare earth ore was mainly achieved by ion exchange reactions between leaching agent ions and rare earth ions adsorbed on the surface of clay.Using(NH_4)_(2)SO_(4) as leaching agent,the leaching process of weathered crust elution-deposited rare earth ore was studied by a multistage counterflow leaching experiment.The leaching behaviors of rare earth ions(RE^(3+)) and aluminum ions(Al^(3+),the major impurity) were investigated based on the composition variations of the leachates from each stage,and the reaction mechanisms of ammonium ions(NH_4^(+)) with both RE^(3+) and Al^(3+) as well as amount of net adsorption of the ore were discussed according to consumption of leaching agent.The results show that the concentration of both RE^(3+) and Al^(3+) in the leachates gradually increases in the stage-by-stage leaching of the fresh ore along with the consumption of NH^(4+),however the amount of them exchanged into the leachates in a single leaching gradually decreases with stage.Meanwhile,sulfate ions(SO_4^(2-)) in the leachates decrease stage-bystage,indicating that besides NH^(4+) consumption through ion exchange reactions there could also be net adsorption of NH^(4+) to the fresh ore.The ratio of adsorption sites in the fresh ore for rare earth,aluminum and net adsorption was calculated to be about 20∶41∶39.During the two series of counterflow leaching experiments,leaching of Al^(3+) always behaves similar to that of RE^(3+) and does not show correlation with pH variation of the leachates(from 4.5 to 4.0).In addition,the analysis shows that under pH of the leaching reactions RE^(3+) is the dominant specie of rare earth while Al^(3+),AlOH_(2)^(+),and Al(OH)_(2)^(+) are the main species of aluminum,thus it is inferred that the ion-exchange stoichiometric ratios of NH^(4+) to rare earth ions and to aluminum ions should be close or equal to 3∶1 and 1.8∶1 respectively according to mass balance during the leaching process.
作者
冯凯
程福祥
吴声
廖春生
严纯华
Feng Kai;Cheng Fuxiang;Wu Sheng;Liao Chunsheng;Yan Chunhua(CREG(Beijing)Research Institute of RE Co.,Ltd,Beijing 100085,China;College of Chemistry and Molecular En-gineering of Peking University,State Key Laboratory of Rare Earth Materials Chemistry and Applica-tions,Beijing National Laboratory for Molecular Sciences,Beijing 100871,China)
出处
《中国稀土学报》
EI
CAS
CSCD
北大核心
2024年第1期102-111,I0004,共11页
Journal of the Chinese Society of Rare Earths
基金
国家重点研发计划资助项目(2019YFC0605005)资助。
关键词
风化壳淋积型稀土矿
多级逆流浸取
离子交换
硫酸铵
净吸附
weathered crust elution-deposited rare earth ore
multistage counterflow leaching
ion exchange
ammonium sulfate
net adsorption
作者简介
冯凯(1994-),男,博士,工程师;通讯联系人:廖春生,男,教授级高级工程师,研究方向:稀土分离和材料化学。E-mail:liao@cre-ol.com。
