A process for decomposing fluorine-containing rare earth molten salt waste slag

Abstract

The invention belongs to the field of resource recycling, and particularly relates to a method for recycling rare earth elements by processing fluorine-contained rare earth molten salt electrolytic waste residues through sodium hydroxide alkaline transfer and hydrochloric acid dissolving treatment. The method comprises the following steps that raw materials of the fluorine-contained rare earth molten salt electrolytic waste residues are dried and made into powder, roasting alkaline transfer and alkali fusant washing and fluoride removal are conducted to obtain calcium fluoride, hydrochloric acid dissolving is conducted, and the pH value of acid soluble material liquid is enabled to reach 12. Importantly, in the production process, low-temperature alkaline transfer, calcium fluoride recycle and caustic soda liquid recycle are conducted, so that compared with other processes, the method has the outstanding advantages that the procedure is simple, energy is saved, the environment is protected, and the primary recovery rate of rare earth is high so that the leaching rate of the rare earth elements can be 98% or above.

Description

technical field [0001] The invention belongs to the field of resource recycling and reuse, and in particular relates to a method for recovering rare earth elements from electrolytic waste residues of fluoride-containing rare earth molten salts by sodium hydroxide alkali conversion and hydrochloric acid dissolution. Background technique [0002] At present, single rare earth metals and functional rare earth alloys are mainly produced by fluoride system oxidation rare earth electrolytic molten salt process. A certain amount of molten salt waste slag will be produced in the rare earth electrolysis process, and these molten salt waste slags contain 20%-70% rare earth (calculated by REO), and most of the rare earth elements exist in the form of fluoride. At present, the most widely used method to deal with molten salt electrolysis waste residue is to burn concentrated sulfuric acid at high temperature to remove fluorine, then leach rare earth sulfate with water, and then recover ...

AI Technical Summary

Problems solved by technology

This method improves the leaching rate of rare earth, but the roasting temperature is too high, the energy consumption is large, the pot loss is large during burning, and the acid consumption is large due to excessive calcium hydroxide during acid dissolution, and the obtained solution contains a large amount of Ca, Ba, etc. Rare earth elements, resulting in high cost of extraction and separation in the later stage

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