METHOD OF PROCESSING SILICATE MATERIALS CONTAINING HEAVY NONFERROUS METALS Russian patent published in 1999 - IPC

FIELD: nonferrous metallurgy. SUBSTANCE: starting material is crushed, subjected to magnetic separation, and ground in two steps involving, after each step, sizing and gravitational separation of sands carried out on inertial separator with rotation speed 250-450 rpm. Material is then floated and valuable components are isolated in three steps. First, material is subjected to autoclave leaching with sodium hydroxide solution (380-450 g/l) at 180-250 C with curing for 45-60 min. First-step residue is caked with calcium oxide at CaO/SiO₂ ratio (1-1.5):1 and temperature 900-1000 C and cake is leached with alkali solution to form calcium-silicate product. The latter is treated with mineral acid solution at pH 1-1.5 for 30-60 min. Method is adequate for processing complex silicate materials containing ferrites and more than 10 wt % silicon oxide in the form of silicates and aluminosilicates, and also at least 0.2 wt % heavy nonferrous metals that are isolated with degree of recovery more than 98.5%. Silicate residues themselves are also commercial products. EFFECT: enhanced process efficiency. 5 cl, 3 tbl, 3 ex