METHOD OF PRODUCING POTASSIUM SULPHATE FROM POLYHALITE ORE Russian patent published in 2015 - IPC C01D5/00 

FIELD: chemistry.

SUBSTANCE: potassium sulphate is produced by crushing polyhalite ore; washing off halite with water; calcining in a furnace; cooling; leaching the calcined polyhalite with water at 98-100°C; precipitating gypsum and filtering from the solution; adding potassium chloride to the obtained filtrate to convert, at 98-100°C, magnesium sulphate with potassium chloride and obtain potassium sulphate, which is filtered and dried. The polyhalite ore is crushed to particle size of 5-20 mm. The polyhalite from which halite is washed off is calcined at a temperature equal to 0.53-0.75 times the melting point of polyhalite. Polyhalite is then ground in hot water to particle size of 0.2-1.0 mm. After filtering gypsum, the obtained schoenite filtrate is mixed with wet schoenite for decomposition. Potassium chloride solution is added to the obtained schoenite solution. The convertible schoenite solution is evaporated.

EFFECT: invention simplifies extraction of potassium sulphate from polyhalite ore, improves quality and degree of extraction of potassium sulphate.

1 dwg, 1 tbl, 1 ex