煤矸石酸溶液中稀土混合萃取优化实验研究

Study on optimized experiment of mixed extraction of rare earths from acid solution of coal gangue

为提高煤矸石多金属提取资源化利用价值,解决实际生产中煤矸石酸浸液中混合稀土分离困难的问题。本研究以贵州煤矸石中和渣酸溶液为原料,Cyanex272-P204为混合萃取剂,探究初始料液pH,Cyanex272体积分数,P204体积分数,相比以及振荡时间等因素对混合稀土RE 3+萃取率以及RE 3+与Fe 2+、Al 3+分离效果的影响,并初步探究了Cyanex272-P204萃取RE 3+的机理。结果表明:初始料液pH值为2.2,Cyanex272体积分数为6%,P204体积分数为8%,相比为1∶1,振荡时间为6 min时,Cyanex272-P204对RE 3+的萃取率达到最大,且此时分离因子β[RE 3+/Fe 2+]和β[RE 3+/Al 3+]有最大值,分别为245.47和41.69,能实现混合稀土与铁、铝的有效分离,混合稀土的萃取焓变ΔH为-3637.96 J/mol,表明萃取过程为放热反应。

In order to improve the value of multi-metal extraction and utilization of coal gangue and solve the problem of difficult separation of mixed rare earth in acid leaching solution of coal gangue in actual production,the extraction mechanism of RE 3+by Cyanex272-P204 preliminarily was explored.The acid leaching solution of Guizhou coal gangue neutralization slag as the raw material,Cyanex272-P204 as mixed extractant was used.The parameters of initial solution pH,Cyanex272 volume fraction,P204 volume fraction,O/A ratio,and extraction time on extraction rate and separation efficiency of mixed rare earth,Fe 2+and Al 3+were investigated.The results show that the extraction rate of mixed rare earth is the highest when the initial feed solution pH is 2.2,Cyanex272 volume fraction is 6%,P204 volume fraction is 8%,O/A ratio is 1∶1 and the extraction time is 6 min.Under this optimum extraction conditions,the separation factor of mixed rare earth is the largest,β(Re 3+/Fe 2+)andβ(Re 3+/Al 3+)reach 245.47 and 41.69,respectively.The effective separation of mixed rare earth,iron and aluminum could be achieved.The enthalpy of extraction of mixed rare earth in this system is-3637.96 J/mol,indicating that the extraction process is exothermic reaction.