Method for preparing aluminum fluoride from aluminum electrolysis fluorine-containing waste

The invention provides a method for preparing aluminum fluoride from aluminum electrolysis fluorine-containing waste, which comprises the following steps of: mixing overhaul slag and carbon slag for size mixing, and carrying out pressurized alkaline leaching, cyanogen removal and solid-liquid separation to obtain alkaline leaching liquid and alkaline leaching slag; carrying out acid leaching on the alkaline leaching residues, and carrying out solid-liquid separation to obtain acid leaching liquid and acid leaching residues; mixing the alkaline leaching solution and the acid leaching solution, neutralizing and precipitating, and separating to obtain regenerated cryolite; mixing the regenerated cryolite and an aluminum electrolyte, and treating to obtain mixed powder; reacting the mixed powder with concentrated sulfuric acid to obtain reaction residues and hydrogen fluoride; adding sodium hydroxide into filtrate obtained after the reaction residues are treated, and performing solid-liquid separation to obtain a