复杂铝电解质体系中锂盐和钾盐对氧化铝浓度的影响

我国铝电解企业所使用的原料氧化铝来源复杂,特别是富含锂、钾元素,造成锂盐、钾盐在铝电解质体系中大量富集,导致铝电解质成分复杂,对氧化铝的溶解过程造成极大影响。依据大量生产控制数据,解析了氟化锂、氟化钾在复杂铝电解质体系中对氧化铝的溶解性能的影响关系。结果表明,电解质体系中的锂盐、钾盐与冰晶石反应生成氟化锂、氟化钾。在低氟化锂浓度(3.00%)时,氧化铝浓度随着氟化锂浓度的增加而降低;在高氟化锂浓度(3.00%)时,氧化铝浓度随着氟化锂浓度的增加而增加。氧化铝的浓度随着氟化钾浓度的增加而增加;在复杂铝电解质体系中氟化锂的浓度控制在1.50%～2.50%可以保持铝电解过程的最优状态,铝电解质体系中尽量避免含氟化钾。

Effects of Lithium and Potassium Salts on Alumina Concentration in Complex Aluminum Electrolyte System

Due to complex sources of alumina in China, especially rich in Li and K elements, lithium salt and potassium salt enrich in aluminium electrolyte system and has a big impact on dissolution process of alumina. Based on a large number of production data, influences of LiF and KF on solubility of alumina in complex aluminium electrolyte system were analyzed. The results show that lithium salt and potassium salt in electrolyte system react with cryolite to form lithium fluoride and potassium fluoride. Concentration of alumina drops with increase of lithium fluoride concentration at low lithium fluoride concentration (<3.00%), and concentration of alumina rises with increase of lithium fluoride concentration at high lithium fluoride concentration (>3.00%). Concentration of alumina rises with increase of fluoride concentration in complex aluminium electrolyte system. Concentration of lithium fluoride in the range of 1.50%-2.50% can keep the optimal state of aluminium electrolysis process, and potassium fluoride should be avoided as much as possible.