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US 4,421,729 AGranted
Preparation of strontium carbonate
AssigneeFMC Corporation
InventorsJohn S. Chiang, David Goldstein
Life of this patent
Estimating the term…
Abstract
Strontium carbonate is prepared by the process of reacting strontium nitrate in an aqueous reaction medium with carbon dioxide to precipitate strontium carbonate product, the nitric acid byproduct that forms being neutralized by the introduction of lime to the reaction medium.
Claims14
The process of preparing strontium carbonate which comprises
- (a) reacting strontium nitrate in an aqueous reaction medium, that is concentrated with respect to strontium nitrate, with carbon dioxide to selectively precipitate strontium carbonate product;
- (b) neutralizing nitric acid byproduct which forms during the reaction by introducing sufficient lime into the aqueous reaction medium to obtain a molar ratio of dissolved calcium to dissolved strontium therein at from 0.1:1 to about 7:1 Ca:Sr;
- and
- (c) recovering the solid strontium carbonate product substantially free of lime and calcium carbonate from the reaction medium.
1 more element
The cyclic process of preparing strontium carbonate from celestite which comprises
- (a) mixing ground celestite ore with greater than a stoichiometric quantity of calcium nitrate in an aqueous mixture to react strontium sulfate in the celestite with calcium nitrate, the aqueous mixture containing insufficient water to solubilize all strontium values in the celestite as strontium nitrate;
- (b) contacting the aqueous mixture, quickly and with vigorous agitation, with additional water to rapidly dissolve and extract soluble strontium nitrate, the total amount of added water being at least equal to the amount required to solubilize essentially all of the strontium nitrate in the aqueous mixture;
- (c) separating the aqueous solution containing solubilized strontium nitrate and unreacted calcium nitrate from the undissolved mixture solids;
- (d) fractionally crystallizing strontium nitrate from the aqueous solution by evaporation of water from the solution;
- (e) separating the crystallized strontium nitrate, the aqueous calcium nitrate solution that remains being recycled to step (a) for reaction with celestite ore;
- (f) redissolving the crystallized strontium nitrate in an aqueous reaction medium;
- (g) reacting strontium nitrate in an aqueous reaction medium, that is concentrated with respect to strontium nitrate, with carbon dioxide to selectively precipitate strontium carbonate product;
- (h) neutralizing nitric acid byproduct which forms during the reaction by introducing sufficient lime into the aqueous reaction medium to obtain a molar ratio of dissolved calcium to dissolved strontium therein at from 0.1:1 to about 7:1 Ca:Sr;
- and
- (i) recovering the solid strontium carbonate product substantially free of lime and calcium carbonate, the aqueous mother liquor containing calcium nitrate and unreacted strontium nitrate that remains being recycled to step (d) or step (g) or both.
7 more elements
Dependencies are inferred from the claim text.