METHOD OF PROCESSING SPHENE Russian patent published in 2000 - IPC

FIELD: chemical industry, more particularly preparation of pigments for paper, plastics and paint materials. SUBSTANCE: sphene is added to H₂SO₄ solution with concentration of 350-550 g/l. 5-10 h later phosphate solution containing 25-30% of P₂O₅ is added to suspension heated to boiling temperature. Amount of phosphate solution binds 20-35% of TiO₂ in sphene phosphate. Phosphate solution is filtrate after sulfate stripping of apatite. During stirring operation TiO₂ nucleus and TiO₃ solution are added. The mixture is maintained during heating for 10 hours and diluted with hot water. Precipitate is separated, washed with water at S:L ratio of 1:(5-6), calcined at 650-750 C. Recovery of TiO₂ is about 95%. Filtration rate of suspension is 500-600 l/sq.m. Oil absorption of pigment is 25.8-27.4 g/100 g; covering power is 49.7-51.0 g/sq. m; content of water soluble salts is 0.55-0.98%. EFFECT: more efficient processing method. 2 cl, 4 ex, 2 tbl