废旧阴极碱性浸出液制备冰晶石

Preparation of Cryolite from Alkaline Leaching Solution of Spent Cathode

以废旧阴极碱性浸出液为原料,采用二氧化碳气体碳分制备冰晶石。结果表明:在二氧化碳流量0.7 L/min、室温、反应时间2.0 h、终点pH 9~10的条件下,碳分产物中冰晶石含量可达到60%,杂质为硅酸铝、结晶水和氢氧化铝。采用氢氟酸除杂,在氢氟酸用量1.75倍理论用量、反应时间2.0 h、反应温度60℃、液固比3的条件下除杂,冰晶石品位可提升至99.50%以上,满足铝电解质量要求,实现了从废旧阴极碱性浸出液中回收利用冰晶石。

Cryolite was prepared from alkaline leaching solution of spent cathode by carbonation with CO.The results show that content of cryolite in carbonation product can reach 60% under the conditions including COflow rate of 0.7 L/min, room temperature, reaction time of 2.0 h, and final pH value of 9—10.The main impurities are AlSiO,Al(OH)and crystal water.Using hydrofluoric acid to remove impurities, the grade of cryolite rises to 99.50% above under the conditions including 1.75 times of theoretical dosage of hydrofluoric acid, reaction temperature of 60 ℃,reaction time of 2.0 h, and L/S=3.This cryolite satisfies the requirement of aluminum electrolysis, and it realizes the recycling of cryolite from alkaline leaching solution of spent cathode.