锂云母复合盐焙烧-水浸提取锂铷铯

采用复合盐焙烧-水浸工艺从锂云母中提取锂、铷、铯,研究了焙烧工艺参数及浸出工艺参数对锂、铷、铯浸出率的影响。结果表明,锂云母精矿焙烧时,复合盐焙烧效果优于单一盐添加剂,CaCl₂+Na₂CO₃组合添加剂具有焙烧时氯气排放少、焙烧矿浸出效果好等优点。从锂云母中回收锂、铷、铯,较佳的焙烧-浸出工艺条件为: CaCl₂+Na₂CO₃组合为焙烧添加剂,锂云母精矿∶CaCl₂∶Na₂CO₃(质量比)=1∶0.5∶0.2,锂云母精矿焙烧温度900 ℃、焙烧时间2 h,对焙烧矿进行室温水浸,浸出时间1 h、液固比2∶1,此时锂、铷、铯浸出率分别为86.64%、92.58%、85.37%。含锂浸出液经2次调节pH值净化除钙,升温至95 ℃后加入饱和Na₂CO₃溶液,结晶得到碳酸锂,样品纯度为99.08％,产品纯度及杂质含量达到一级碳酸锂标准。沉锂母液采用溶剂萃取法分离铷、铯,铯萃取率达到99%以上,铷洗脱率达到96%左右。

Extraction of Lithium,Rubidium and Cesium from Lepidolite Using Composite Salt Roasting and Aqueous Leach Process

A processing technique consisting of composite salt roasting and aqueous leach was adopted in the experiment to extract lithium, rubidium and cesium from lepidolite, and the effects of roasting processing conditions and leaching processing conditions on the leaching rates of lithium, rubidium and cesium were all investigated. The results show that the effect of composite salt additive is better than that of single salt additive in the roasting of lepidolite. It is shown that the combined additive of CaCl₂+Na₂CO₃ can lead to less chlorine emission during the roasting process, and also bring in a good leaching effect of roasted ore. Lithium, rubidium and cesium can be recovered from lepidolite with the optimal roasting and leaching conditions. The lepidolite concentrate is firstly subjected to roasting at 900 ℃ for 2 h, by adding a combination of CaCl₂+Na₂CO₃ as the additive, with lepidolite concentrate, CaCl₂ and Na₂CO₃ in a mass ratio of 1∶0.5∶0.2. The obtained roasted ore is subjected to an aqueous leach at the room temperature for 1 h with liquid-solid ratio of 2∶1, leading to the leaching rates of lithium, rubidium and cesium at 86.64%, 92.58% and 85.37%, respectively. The lithium-containing leaching solution is then purified to remove calcium by adjusting pH value twice, and saturated Na₂CO₃ is added after the temperature is raised to 95 ℃. The finally obtained product of lithium carbonate after crystallization can have purity up to 99.08%, showing that both its purity and impurity content reach the standard for first-class lithium carbonate. Then, rubidium and cesium can be separated from the mother liquor after lithium precipitation by solvent extraction, showing the extraction rate of cesium is over 99%, and the elution rate of rubidium is about 96%.