Ultrasonic enhanced water washing method for extracting sodium fluoride from spent pot lining

Abstract A large amount of spent pot lining (SPL) is produced by cryolite-alumina melting electrolysis process, and the fluoride content in leaching solution up to 6000 mg/L, which belongs hazardous waste. If SPL not handled effectively, it will cause great harm environment. Because NaF rich an important raw material for synthesis cryolite carbonation, this paper uses as extract NaF. On basis exploring process conditions water washing NaF, ultrasonic wave was introduced enhance mass transfer effects cavitation on compared. The results show that waves can effectively shorten time reach equilibrium further improve efficiency leaching. Under optimal determined experiment, when power 400 W, shortened from 50 min 40 min, increased 67.25 % 70.42 %. While improving efficiency, consumption reduced, purity recovered product 96.82 This research provides a technical reference harmless low cost aluminium industry.