PURIFIED CALCIUM NITRATE SOLUTION PREPARATION METHOD Russian patent published in 2004 - IPC

FIELD: inorganic compounds technology.

SUBSTANCE: invention deals with production of calcium nitrate suitable for use as hothouse farming fertilizer and as intermediate for production of pure calcium salts, e.g. calcium carbonate. For that, calcium nitrate tetrahydrate isolated from nitric acid extract appearing in technology of nitric acid processing of phosphate stock into complex fertilizers is treated with calcium carbonate or aqueous suspension thereof at temperature above 20^оС, said calcium carbonate being, more specifically, solid product obtained by treating crude solution of calcium nitrate tetrahydrate with ammonium carbonate (to reach pH 3-5, preferably 4.1-5.0) and said suspension, before separation of impurity precipitate, being additionally treated with an alkali reagent, preferably calcium hydroxide, and still more preferably in the form of aqueous suspension thereof, to obtain pH 6-8. Impurity precipitate is then separated from desired product while maintaining calcium nitrate concentration in purified solution within a range of 35-45 wt %.

EFFECT: simplified process, increased fullness of impurity precipitation, and reduced expenses on reagents.

5 cl, 1 tbl, 3 ex