METHOD OF TREATING NATURAL PHOSPHATE FOR EXTRACTION OF RARE-EARTH ELEMENTS Russian patent published in 2015 - IPC C22B59/00 C22B3/08 

FIELD: chemistry.

SUBSTANCE: invention relates to extraction of rare-earth elements from a natural phosphate. The method includes sulphuric acid decomposition of the phosphate into mineral fertilisers to obtain phosphogypsum. Further, the method includes separating the phosphogypsum and sulphuric acid decomposition of the phosphogypsum by successively treating multiple portions of phosphogypsum with one sulphuric acid solution. Further, the method includes separating the acid-resistant part of phosphogypsum, crystallising the rare-earth element concentrate, separating the rare-earth element concentrate by filtering to obtain a sulphuric acid filtrate and processing the rare-earth element concentrate. The separated acid-resistant part of phosphogypsum is treated with ammonia and carbon dioxide gas to obtain a calcium carbonate precipitate and ammonium sulphate solution. The calcium carbonate is separated, the ammonium sulphate is heat treated to obtain ammonium bisulphate and ammonia, which is returned for treating the acid-resistant part of phosphogypsum, and sulphuric acid solution, which is fed for decomposing the phosphate, is obtained from the obtained ammonium bisulphate and sulphuric acid filtrate with addition of sulphuric acid.

EFFECT: broader capabilities for extracting rare-earth elements from a natural phosphate, reduced formation of wastes and low consumption of sulphuric acid.

8 cl