METHOD OF THE EXTRACTION OF RARE-EARTH MATERIALS DURING PROCESSING OF THE PHOSPHOGYPSUM

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FIELD : chemistry.SUBSTANCE : invention is meant for extracting rare-earth metals from phosphogypsum obtained in production of phosphorus fertiliser during sulphuric acid treatment of apatite. The method of extracting rare-earth metals from phosphogypsum involves converting phosphogypsum, dissolving the converted chalk to obtain an insoluble residue containing rare-earth metals. The obtained insoluble residue containing rare-earth metals is dissolved in nitric acid solution at solid-to-liquid ratio of 1 : 1.5 to obtain a solution and an insoluble residue. The insoluble residue is then washed with water; the obtained solution is mixed with the washing solution; the mixed solution is neutralised to acidity of 0.5-0.25 N with concentrated aqueous ammonia solution and taken for precipitation of rare-earth metal oxalates. The oxalates are precipitated with saturated oxalic acid solution; the residue is washed with 1.5-2.5% oxalic acid solution at solid-to-liquid ratio of 1 : 2-3. The oxalates are then dried and calcined until rare-earth metal oxides are obtained.EFFECT : high efficiency of the process of extracting rare-earth metals by cutting duration of the process, the amount of reagents, the size of the equipment, energy resources and avoiding labour-consuming processes.2 cl, 4 ex