| 简介 |
FIELD : chemistry.SUBSTANCE : invention relates to a method of extracting rare-earth elements from nitrate-phosphate solutions from apatite processing. The method comprises dissolving apatite in nitric acid, freezing out calcium (strontium) nitrate, precipitating hydrate-phosphates of rare-earth elements and calcium (strontium), dissolving the precipitate in nitric acid, adding calcium (strontium) nitrate obtained from the freezing out step with concentration of 800-1000 g/l and heated to 40-50°C to the solution, wherein content of rare-earth elements (in terms of oxides) is kept at 40-60 g/l, and excess nitric acid 1-2 mol/l, followed by extraction of rare-earth elements with tributyl phosphate in the presence of calcium nitrate, washing and re-extraction, wherein the extract is washed with evaporated re-extraction product to rare-earth element concentration of 250-300 g/l. 70-90% of the obtained solution is removed in form of a finished product and the remaining solution is taken for washing, wherein the raffinate, which contains calcium nitrates and iron and aluminium impurities, is taken for recovering calcium (strontium) nitrate by freezing out or precipitating impurities with calcium oxide.EFFECT : invention enables to avoid use of concentrated and explosive ammonium nitrate solutions, reduces consumption of nitric acid and improves efficiency of using apatite processing by-products.2 cl, 6 tbl, 4 ex |
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