METHOD OF PRODUCING CHROMIUM ANHYDRIDE Russian patent published in 2009 - IPC C01G37/33 

FIELD: chemistry.

SUBSTANCE: present invention can be used in making chromium anhydride, used in chemical, paint and coating, textile, metallurgical and other industries. The method of producing chromium anhydride involves leaching a chromite concentrate at 140-160 °C with a mixture of 60-62% sulphuric acid and a catalyst - chromium anhydride. The suspension undergoes centrifugal separation. Chromium sulphate, obtained from leaching, is oxidised to chromic acid through electrolysis. The electrolyte solution is evaporated at 140-150 °C temperature until 950-1100 g/l concentration of sulphuric acid in the evaporated solution is achieved. Crystals of chromium anhydride are separated from the mother solution through centrifugal separation and the end product is dried. Before sulphuric acid leaching, the chromite concentrate is concentrated through gravitation. The amount of catalyst when leaching is 70-100% of content of iron (II) oxide in the chromite concentrate. After separation from the mother solution, chromium anhydride crystals are further washed in sulphuric acid with 60-62% concentration at 140-150 °C.

EFFECT: invention allows for obtaining chromium anhydride from poor ore mixtures with high product output and low content of impurities.

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