Method for efficiently recovering rare earth and fluorine elements from rare earth molten salt electrolysis slag

Abstract

The present application belongs to the technical field of rare earth electrolytic slag resource recycling, and relates to a method for efficiently recycling rare earth and fluorine elements from rare earth molten salt electrolytic slag. The rare earth molten salt electrolytic slag is mixed with a silicon source and calcined to obtain a defluorination calcination slag and a gas phase containing silicon tetrafluoride, the gas phase is introduced into an absorption liquid to react, and fluorosilicic acid dispersion and silicon dioxide are obtained; an acid liquid is added to the solid phase slag to perform leaching reaction, an aluminum source and a sodium source are added to the fluorosilicic acid solution, the pH value is controlled, and cryolite is prepared through precipitation reaction to realize high-value conversion of fluorine. The present application completely converts the insoluble rare earth fluoride into soluble oxide, improves the rare earth leaching rate to more than 98%, recycles and converts the fluorine element which pollutes the environment into high-value cryolite product, realizes the cyclic utilization of silicon dioxide, greatly reduces the raw material cost, has less three-waste emissions, and meets the concept of green production.