METHOD FOR PREPARING SODIUM HEXAFLUOROSCANDIATE Russian patent published in 2004 - IPC

FIELD: inorganic chemistry, chemical technology.

SUBSTANCE: invention relates to technology for preparing chelate compounds of scandium. The parent scandium carbonate is dissolved in hydrochloric or nitric acid to pH = 1-2. Then ammonium fluoride and scandium-containing chloride or nitrate solution in the ratio (mole) sodium fluoride : ammonium fluoride : scandium = (3.1-3.2):(3.0-3.1):1, respectively, are added sequentially to the saturated and heated to 80-95^oC solution of sodium fluoride. Chelate scandium salt is precipitated. Pulp is kept at stirring for 20-40 min. Precipitated deposit of sodium hexafluoroscandiate is filtered off, washed out with acetone and dried at temperature 100-150^oC for 2-3 h. Mother liquor obtained after filtration of sodium hexafluoroscandiate is treated with hydrochloric or nitric acid up to the ratio (mol) fluoride ions : hydrogen ions = 1:(0.9-0.95). The obtained solution is used for treatment of the parent scandium carbonate, filtrate is separated and discarded and precipitate containing scandium carbonate and fluoride is fed to the process head. Invention provides preparing crystalline precipitates that promotes to formation more pure compounds and elevating filtration rate, diminishing amount of formed fluoro-containing sewage wherein the residual concentration of fluoride ions in discharge solutions doesn't exceed 3-5 mg/l.

EFFECT: improved preparing method.

2 tbl, 1 ex