METHOD OF PROCESSING BAUXITE Russian patent published in 1997 - IPC

FIELD: silica production. SUBSTANCE: sludge prepared from bauxite and return solution is heated with separator steam to 80-100 C and kept at this temperature to completion of desiliconization of sludge. The latter is then heated in heating autoclaves, leached with solution in reaction autoclaves, and cooled in separators to yield leached sludge, separator steam, and condensate. Leaching in reaction autoclaves is conducted in evaporation mode to increase sodium oxide concentration by 10-30 g/l thus producing secondary steam. Sludge to be kept at 80-100 C has sodium oxide concentration by 10-30 g/l lower than leaching solution concentration. Prior to be heated in heating autoclaves, sludge is heated in apparatuses with separator steam to 140-175 C, whereas, in heating autoclaves except the last one, heating is effected with secondary steam from reaction autoclaves to 180-230 C through heating surface. In the last heating autoclave, heating is effected with secondary steam in contact mode to 220-265 C. EFFECT: improved process flowsheet. 6 cl, 1 dwg