METHOD OF PRODUCING ALUMINA FROM CHROMIFEROUS BAUXITES Russian patent published in 2017 - IPC C01F7/08 C01G37/04 C22B3/04 

FIELD: chemistry.

SUBSTANCE: method of producing alumina from chromiferous bauxites comprises wet batch sintering, leaching of sintered material with flush water to produce aluminate solutions, whereof aluminum hydroxide is extracted. Bauxite is subjected to wet grinding on the concentrated reusable soda solution at a volume ratio of W:T=3:1 separate from the limestone. A pulp with a particle size of less than 0.05 mm is obtained. The pulp is subjected to magnetic separation to obtain magnetic and non-magnetic products. The magnetic product with chromium oxide (III) content from 25 to 30% is taken for processing to sodium chromate. The non-magnetic product with limestone fines and fresh soda is taken for the batch adjustment. Thereafter, the batch is sintered. The resulting sintered material is leached with flush water to produce aluminate solutions, whereof aluminium hydroxide is extracted. Aluminium hydroxide is filtered, washed and taken for calcination.

EFFECT: invention allows to increase the complexity of processing low-quality bauxite to produce alumina and sodium chromate, reduce the environmental pressure due to the extraction of the chromium compounds.

6 dwg, 3 ex