Recovery of valuable metals from lepidolite by atmosphere leaching and kinetics on dissolution of lithium

锂云母矿中有价金属的常压提取及锂的溶出动力学（英文）

The lepidolite located in Yichun, Jiangxi Province, China, was adopted to investigate the recovery of alkali metals and leaching kinetics of lithium with sulphuric acid solution under atmospheric pressure. The results show that the recoveries of alkali metals were achieved under the leaching conditions: mass ratio of lepidolite with particle size less than 180 μm to sulphuric acid 1.2, leaching temperature 411 K, liquid-solid ratio 2.5∶1, and leaching time 10 h. Under the selected conditions for leaching experiment, the leaching rates of lithium, potassium, rubidium and caesium are 94.18%, 93.70%, 91.81% and 89.22%, respectively. The X-ray diffraction analysis for leaching residue indicates that no insoluble product forms during leaching. The chemical compositions of leaching residue reveal that trace iron, manganese and calcium disappear after acid leaching. The kinetics of leaching process for lithium follows shrinking core model of mixed control and the apparent activation energy is 17.21 kJ/mol. The reaction orders with respect to sulphuric acid concentration and liquid-solid ratio are determined to be 2.85 and 1.66, respectively. A semi-empirical rate equation was obtained to describe the leaching process. The kinetic analysis shows that the leaching process is controlled by diffusion through the insoluble layer of the associated minerals.

研究产于江西省宜春市的锂云母矿在硫酸体系常压浸出过程中有价碱金属元素的提取,建立该反应过程中锂的溶出动力学方程。结果表明:在粒径小于180μm物料与硫酸质量比为1.2?1、温度为411 K、液固比为2.5?1的条件下浸出10 h,锂、钾、铷和铯的浸出率分别为94.18%、93.70%、91.81%和89.22%。浸出矿渣的X射线衍射分析结果表明,浸出过程中无不溶物产生,浸出渣化学组分表明矿相中微量的铁、锰、钙等随酸浸过程的进行逐步消失。锂的浸出动力学行为符合混合控制的收缩核模型,反应的表观活化能为17.21k J/mol,硫酸浓度和液固比相应的反应级数分别为2.85和1.66。得到半经验速率方程以描述整个浸出过程。动力学分析结果表明,浸出过程由伴生矿物的不溶层扩散控制。