METHOD OF PROCESSING KYANITE CONCENTRATE Russian patent published in 2013 - IPC C22B5/10 

FIELD: chemistry.

SUBSTANCE: method involves mixing a concentrate, a carbonaceous reducing agent and a pore-forming additive in form of ammonium sulphate, pelletising the obtained mixture, firing and holding at maximum temperature with reduction of silicon dioxide to a gaseous monoxide, crushing the obtained sinter, treatment thereof with ammonium bifluoride and calcining the reaction mass to obtain an aluminium-containing product, wherein ammonium sulphate is taken in an amount of 10-20% of the mass of the concentrate; before pelletising, the mixture is milled to obtain particles with size of 50-75 mcm in amount of at least 80%; the mixture is fired at temperature of 1690-1750°C; ammonium bifluoride is taken in amount of 0.4-14% of the mass of the sinter; and the reaction mass is calcined at 700-900°C. Before treatment with ammonium bifluoride, the sinter can be treated with 10-20% hydrochloric acid. The degree of extraction of aluminium oxide from the concentrate is increased by 1.3-9.9%. Content of aluminium oxide in the end product reaches 97.7% with content of silicon oxide impurities of 0.13-1.0%.

EFFECT: high content of aluminium oxide in the end product while reducing content of silicon oxide impurities.

3 cl, 6 ex