METHOD FOR PRODUCING CALCIUM CARBONATE Russian patent published in 2023 - IPC C01F11/18 C01B25/18 C01D5/00 B09B3/00 B09B101/00 

FIELD: raw materials hydrometallurgical processing.

SUBSTANCE: invention relates to hydrometallurgical processing of mineral raw materials and to environmental protection and can be used in the complex processing of phosphogypsum. First, phosphogypsum is washed with water for 1-2 hours at a temperature of 60 to 70°C. The resulting suspension is filtered to obtain a solution of sulfuric and phosphoric acids and washed phosphogypsum. A solution of sulfuric and phosphoric acids is sent to the phosphoric acid production cycle. The washed phosphogypsum is sent for conversion with a sodium carbonate solution, followed by separation of the precipitate from the solution. The solid phase is the target product - deoxidized calcium carbonate, and the liquid phase is a solution of sodium sulfate, which is sent for evaporation to obtain the sodium salt of sulfuric acid.

EFFECT: preliminary washing of phosphogypsum makes it possible to reduce the content of residual acids in the target product and increase its yield.

1 cl, 1 tbl, 17 ex