氯化钙-盐酸浸出氟化锂中的锂

Calcium Chloride-Hydrochloric Acid Leaching Lithium in Lithium Fluoride

使用无水氯化钙与盐酸浸出工业氟化锂中的锂,得到氯化锂溶液与氟化钙渣。分别研究了浸出时间、反应温度、盐酸浓度、初始液固比、氯化钙/氟化锂摩尔比对锂浸出率以及浸出液浸出效果的影响。实验结果显示,在温度为80℃、浸出时间2.5h、盐酸浓度0.2 mol·L^(-1)、液固比8 mL/g、CaCl_(2)/LiF摩尔比0.4、搅拌速率400 r·min^(-1)的条件下达到最佳浸出效果,浸出率达到73.3%,浸出液中锂浓度达到29.4 g·L^(-1),钙浓度10.5 g·L^(-1),氟浓度0.385 g·L^(-1)。浸出液后续经回调pH值以及除钙后,可通过加纯碱高温沉锂制备碳酸锂或者蒸发浓缩制备氯化锂,浸出渣可以通过二次酸浸的方式提高锂的回收率以及氟化钙的纯度。

Lithium in industrial lithium fluoride is leached with anhydrous calcium chloride and hydrochloric acid to obtain lithium chloride solution and calcium fluoride slag. The effects of leaching time, reaction temperature, hydrochloric acid concentration, initial liquid-to-solid ratio, calcium chloride/lithium fluoride molar ratio on the leaching rate of lithium and the leaching effect of the leaching solution were studied respectively. The experimental results show that the leaching effect is under the conditions of temperature 80 ℃, leaching time 2.5 h, hydrochloric acid concentration 0.2 mol·L^(-1), liquid-solid ratio 8 mL/g, CaCl_(2)/LiF molar ratio 0.4, and stirring rate 400r·min^(-1). Preferably, the leaching rate reaches 73.3 %, the lithium concentration in the leaching solution reaches 29.4 g·L^(-1), the calcium concentration is 10.5 g·L^(-1), and the fluorine concentration is 0.385 g·L^(-1). After the pH value of the leaching solution is adjusted and the calcium is removed,soda ash can be added to prepare lithium carbonate, or lithium chloride can be prepared by evaporation and concentration. The secondary acid leaching method improves the recovery rate of lithium and the purity of calcium fluoride.