METHOD OF PRODUCING SODIUM MONOCHROMATE Russian patent published in 2015 - IPC C01G37/14 

FIELD: chemistry.

SUBSTANCE: invention can be used in chemical industry. A method of producing sodium monochromate includes two-step calcination of a mixture which contains chromium ore and calcined soda, leaching the obtained sinter and filtering the sinter pulp. At the first step of preparing the mixture, the soda is taken in an amount of 60-70% of the stoichiometric amount for oxidation of Cr₂O₃, and at the second step in an amount of 90-110% of the stoichiometric amount for oxidation of Cr₂O₃. Part of the dried residue after leaching the sinter from the first step can be returned to the first step in amount of 30% of the weight of the ore. The mixture at both steps is calcined at 1200-1300°C.

EFFECT: invention prevents skull formation in calcining furnaces, increases output of sodium monochromate to 90%, increases efficiency by one and a half times, reduces the amount of wastes by more than double and toxicity of the wastes with respect to content of hexavalent chromium by 15 times.

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