FIELD: chemistry.
SUBSTANCE: invention relates to production of calcium nitrate, which is used as fertilizer in greenhouses, in chemical/mining industry or as an initial reagent for obtaining pure calcium salts. Purified calcium nitrate solution is obtained by decomposing the apatite concentrate with nitric acid or recycled nitric acid solutions. Calcium nitrate is extracted by freezing out. Calcium nitrate tetrahydrate crystals are separated from the nitric-phosphoric acid solution by filtration and the calcium nitrate tetrahydrate crystals are dissolved. Calcium nitrate solution is treated with chalk, followed by separation of the impurity precipitate by filtration. Impurity precipitate is treated with nitric acid solution with subsequent neutralization with ammonium carbonate solution. Precipitate of phosphate and calcium fluoride is separated by filtration and returned to the stage of decomposition of the apatite concentrate with nitric acid or recycled nitric acid solutions.
EFFECT: enabling use of sediment of impurities in the main production, which allows returning valuable components and eliminating formation of wastes.
3 cl, 3 ex
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