METHOD FOR EXTRACTING RARE EARTH METALS FROM PHOSPHOGYPSUM

摘要

The invention relates to the field of recycling industrial waste and to the field of environmental protection and can be used in the chemical industry, in the production of building materials, and also in other production areas associated with the use of a gypsum binder and rare earth metals. The essence of the invention consists in that phosphogypsum is processed with a sulphuric acid solution, the solid phosphogypsum phase is separated from the solution, insoluble compounds of rare earth metals are precipitated from the resulting solution by the introduction of oxalic acid or soluble salts thereof in a stoichiometric amount of 250-300 mol% based on rare earth metals in solution, with the sulphuric acid solution being neutralized to a pH value of 1.0-2.5, after which the oxalate residue is separated from the parent solution, and is rinsed, dried and calcined. After separation from the sulphuric acid solution, the solid phosphogypsum phase is rinsed with water, and at least some of the rinsing water together with residual sulphuric acid washed out of the phosphogypsum is returned for processing the following batch of phosphogypsum.