| 简介 |
FIELD : chemistry.
SUBSTANCE : invention can be used in chemical industry. Method of processing calcium sulphate containing rare-earth elements involves leaching calcium sulphate dihydrate, containing rare-earth elements, with sulphuric acid to produce a suspension consisting of a solid phase containing said calcium sulphate dihydrate, and a liquid phase containing said rare-earth elements in a solution. Solid and liquid phases are separated. Sulphuric acid for leaching has concentration of 2 to 25 wt% per total weight of solution. Leaching is performed while stirring for a period of time from 0.5 to 4 hours. Before said leaching step, method includes a step of ripening calcium sulphate hemihydrate containing said rare-earth elements, with crystallisation to obtain calcium sulphate dihydrate during absorption of residual water and/or residual moisture. Ratio of sulphuric acid/ripened calcium sulphate at leaching step is 0.1-2.25. Leaching step precedes a step of grinding crystals of calcium sulphate dihydrate, formed during ripening, for a period of time from 5 to 20 minutes.
EFFECT : invention increases output of rare-earth elements when processing phosphogypsum and purity of phosphogypsum.
12 cl, 7 tbl, 8 ex |
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