METHOD FOR HYDROCHEMICAL PROCESSING OF ALUMINOSILICATE STOCK Russian patent published in 2002 - IPC

FIELD: nonferrous metallurgy. SUBSTANCE: invention, in particular, relates to processing into silica of low-grade aluminosilicate stock, for example high-silica low-ferriferous bauxites, off-balance bauxite ores, and red muds. Processing includes: preparing stock suspension in high-module aluminate solution, high-pressure leaching of Beyer-branch red muds in presence of lime-containing additive, separating hydro-garnet sludge from medium-module solution, adding recycled calcium hydroxide to medium-module aluminate solution to separate tricalcium hydroaluminate precipitate therefrom and to obtain highmodule solution, evaporating the latter and utilizing it for preparation of suspension of red mud and lime- containing additive, regenerating calcium hydroxide from tricalcium hydroaluminate and returning the former into the medium-module aluminate solution treatment stage. In particular, suspension of crushed calcium oxide and/or hydroxide/sodium ferrite mix in high-module solution is used as lime-containing additive during high-pressure red mud leaching operation; the latter operation in high-module solution with liquid/solids ratio from 3 to 7 is carried out in presence of lime-containing additive in amounts providing formation of medium-module solution with molar ratio Na₂O_ku/Al₂O₃ between 7.5 and 9.5; and regeneration of calcium hydroxide from tricalcium hydroaluminate precipitate is carried out under pressurized conditions and temperature 205-240 C utilizing high-module aluminate solution with Na₂O_ku concentration 240-280 g/cu.dm and molar ratio Na₂O_ku/Al₂O₃, between 25 and 35. EFFECT: reduced consumption of lime, increased alumina regeneration level, and increased productivity of red mud-leaching installations. 1 tbl