铝系成型锂吸附剂性能测试评价与对比

Performance evaluation and comparison of aluminum-based granulated lithium adsorbent

我国察尔汗盐湖卤水中蕴含丰富的锂资源,但总体品位较低,具有锂浓度低、镁锂比高的特点,导致开发难度很大。吸附法是针对高镁锂比卤水进行提锂的有效方法,其中铝系锂吸附剂具有洗脱无溶损的优势,目前已在盐湖提锂工业中应用。分别对两种工业化铝系锂吸附剂A、B以及实验室自制吸附剂C进行了系统化表征与吸附性能评价。实验结果显示三种成型吸附剂的有效成分均是锂铝层状氢氧化物,在静态吸附条件下,25℃时吸附剂A、B、C对察尔汗老卤中锂的吸附量分别为2.23、0.45、4.90 mg·g^(-1),吸附动力学均符合拟二级动力学方程,不同温度下吸附等温线拟合结果表明Sips三参数模型能够准确描述三种吸附剂的吸附过程。

Lithium resources are abundant in Qarhan Salt Lake in China.However,the overall grade is low,with the characteristics of low lithium concentration and high magnesium-lithium ratio,which makes development difficult.It has been proved that the adsorption method is effective for extracting lithium from brines with an ultrahigh Mg/Li ratio,especially,the lithium aluminum double layered hydroxides is the only adsorbent for industrial application relying on the advantage of elution without dissolution.In this work,the laboratory-made granulated adsorbent(C)and other adsorbents(A,B)that have been industrialized are evaluated to compare the adsorption performances.Through the characterization analysis of these adsorbents,the adsorbent C displays a good mechanical strength without dissolution or powder lose,declaring a great granulation process.The adsorption capacities of adsorbent A,B and C are 2.23 mg·g^(-1),0.45 mg·g^(-1) and 4.90 mg·g^(-1),respectively.All adsorption courses are in accordance with the pseudo-second-order kinetic equation.The fitting results of adsorption isotherms at different temperatures show that the Sips three-parameter model can describe the adsorption of the three adsorbents accurately.