METHOD OF PROCESSING WASTE POTASSIUM BIFLUORIDE Russian patent published in 2017 - IPC C01D3/02 

FIELD: chemistry.

SUBSTANCE: exhaust potassium bifluoride (EBFP) is crushed, mixed with aqueous potassium hydroxide or potassium carbonate, or potassium bicarbonate, taken in stoichiometric ratio to the content of potassium bifluoride in EBFP. The resulting slurry is hold with stirring at 80-90°C for 20-24 hours, then it is filtered. A portion of the filtrate is directed to evaporation at a temperature of 120-135°C to get potassium fluoride dihydrate. Another portion of the filtrate is directed to a hydrofluorination stage where it is passed through the hydrogen fluoride to achieve pH 2. The resulting solution is stirred for another 2-3 hours, then cooled from 10 to 0°C. Potassium bifluoride precipitated crystals are filtered and dried at 130°C.

EFFECT: invention allows to recycle the spent potassium bifluoride to products having a demand in the industry, to obtain potassium hydrogen bifluoride and potassium fluoride dihydrate with qualifications not lower than pure.

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