METHOD OF ALUMINA RECEIVING FROM BAUXITE Russian patent published in 2009 - IPC C01F7/46 

FIELD: metallurgy.

SUBSTANCE: method of alumina receiving from bauxite by Baeyer process includes washing of aluminium hydrate by hot water from sodium oxalate, desoxalation of part or whole flow of industrial water by lime milk, separation of formed sediment from alkali solution and return of alkali solution into the process after evaporation. Desoxalation is implemented in two stages, herewith at the first stage treatment of industrial water is implemented by formed in the end of desoxalation process sediment in amount not less than 20 g/l of solid, and at the second stage - by lime milk, which is introduced up to finish of desoxalation process from the calculation of molecular ratio CaO_ak/Na₂O_ox=1÷1.1. Separation of formed sediment during the desoxalation process is implemented on chamber filter-press with return of filtrate for evaporation, of sediment - partly on the first stage of desoxalation, and excess is withdrawn from hydrochemical process.

EFFECT: minimisation of lime consumption, introduced into the process, losses of alumina and alkali with formed sediment, reduction of lime consumption in the form of lime milk 2-3 time and reduction of alumina losses in proportion to amount of introduced lime milk at redistribution of industrial water desoxalation.

1 dwg, 1 tbl, 2 ex, 2 cl