METHOD FOR PREPARING PIGMENT FROM SCHUNGITE Russian patent published in 2003 - IPC

FIELD: chemical industry. SUBSTANCE: 1000 kg of schungite with ash content 70% is crushed and ground to particles size 0.01-1 mm, treated with 10-20% HCl solution and washed out with water to pH value of aqueous extract 5.5-6.5. Washed out product is dried to moisture content 0.5-2.5%. During washing out classification ("wet classification") can be carried out simultaneously. After drying classification ("dry classification") can be carried out. Method is simple with respect to equipment using, it provides reducing hazard flows and allows using schungite with rather low carbon content from 30%. Pigment shows thermal stability at 900-1000 C. Method can be used for preparing both black and light-red pigments after additional roasting the prepared pigment in oxidative atmosphere. Invention can be used for preparing thermostable and chemically stable paint and varnish compositions, light-adsorbing panels, composition and building materials. EFFECT: improved preparing method. 3 cl, 4 tbl, 3 ex