Abstract:Cryolite was prepared from alkaline leaching solution of spent cathode by carbonation with CO2. The results show that content of cryolite in carbonation product can reach 60% under the conditions including CO2 flow 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 Al2SiO5, Al(OH)3 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.