Abstract Lithium carbonate is the primary product of the lithium extraction process and is an important compound for the battery making industry. A major step in the conventional sulfuric acid extraction of lithium from mineral ore is the precipitation of lithium carbonate from lithium sulfate media by sodium carbonate addition. Because of the high solubility of lithium carbonate in water and challenges with separating and removing sodium sulfate from the product, this step has a low lithium recovery efficiency as lithium carbonate, and it is difficult to achieve the desirable product purity. In this study, the crystallization process of lithium carbonate is investigated thoroughly. The effect of several operating parameters, including initial salt concentration, reaction temperature, impurity presence, seeding, and feeding rate of sodium carbonate solution to lithium sulfate solution on the lithium recovery efficiency, product purity, reaction equilibrium time, product particle size and crystal morphology is investigated. Results indicate that mixing the lithium sulfate and sodium carbonate solutions both at 2.0 mol/L concentration at 45 °C and 300 rpm agitation rate followed by cooling crystallization of sodium sulfate byproduct produces lithium carbonate with 90% lithium recovery and 99.0% purity. With additional dissolution and recrystallization steps, a lithium carbonate product with over 99.5% purity is produced.

中文翻译：

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提锂过程中硫酸盐介质中碳酸锂结晶影响因素的分析与研究

摘要 碳酸锂是锂提取过程的主要产物，是电池制造行业的重要化合物。从矿物矿石中常规硫酸提取锂的一个主要步骤是通过添加碳酸钠从硫酸锂介质中沉淀碳酸锂。由于碳酸锂在水中的溶解度高，且产品中的硫酸钠分离脱除困难，因此该步骤作为碳酸锂的锂回收效率较低，难以达到理想的产品纯度。本研究对碳酸锂的结晶过程进行了深入研究。几个操作参数的影响，包括初始盐浓度、反应温度、杂质存在、晶种、考察了碳酸钠溶液向硫酸锂溶液的加料速率对锂回收效率、产物纯度、反应平衡时间、产物粒径和晶体形貌的影响。结果表明，将浓度为 2.0 mol/L 的硫酸锂和碳酸钠溶液在 45 °C 和 300 rpm 搅拌速率下混合，然后将硫酸钠副产物冷却结晶，产生具有 90% 锂回收率和 99.0% 纯度的碳酸锂。通过额外的溶解和重结晶步骤，生产出纯度超过 99.5% 的碳酸锂产品。结果表明，将浓度为 2.0 mol/L 的硫酸锂和碳酸钠溶液在 45 °C 和 300 rpm 搅拌速率下混合，然后将硫酸钠副产物冷却结晶，产生具有 90% 锂回收率和 99.0% 纯度的碳酸锂。通过额外的溶解和重结晶步骤，生产出纯度超过 99.5% 的碳酸锂产品。结果表明，将浓度为 2.0 mol/L 的硫酸锂和碳酸钠溶液在 45 °C 和 300 rpm 搅拌速率下混合，然后将硫酸钠副产物冷却结晶，产生具有 90% 锂回收率和 99.0% 纯度的碳酸锂。通过额外的溶解和重结晶步骤，生产出纯度超过 99.5% 的碳酸锂产品。