METHOD OF PRODUCING IRON OXIDE PIGMENTS AND SULPHATE OF POTASSIUM FERTILISERS Russian patent published in 2015 - IPC C09C1/24 C01D5/00 C05D1/02 

FIELD: chemistry.

SUBSTANCE: invention can be used in chemical industry. A suspension of nucleating seeds is prepared to obtain iron oxide pigments. At the step of oxidising scrap metal in an acidic medium, 20% aqueous potassium hydroxide solution is used to neutralise the acid and adjust pH. The pigment is washed multiple times. Effluent with potassium sulphate concentration of 5-10% is fed into a vacuum crystallisation apparatus for evaporating solutions. The potassium sulphate-contaminated process water is converted to pure water with salt concentration of 150 g/m³ by evaporation and condensation. The water is used in producing iron oxide pigments. The potassium sulphate obtained from evaporation is used as potassium fertiliser.

EFFECT: invention enables to prevent formation of contaminated waste water, solid wastes and ammonia vapour emissions and to obtain potassium sulphate as an additional product.

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