METHOD OF SPHENE CONCENTRATE PROCESSING Russian patent published in 2001 - IPC

FIELD: chemical industry. SUBSTANCE: method involves addition of 1300 ml of H₂SO₄ and (NH₄)₂SO₄ taken in the amount of 0.2-0.5% of concentrate mass to 1 kg of sphene concentrate. Mixture is heated to 80-90 C and in 2 h heated concentrated H₂SO₄ is added. Mixture is kept, cooled, precipitate (sulfate cake) is repulped in H₂SO₄ solution, filtered off and added to iron-free water. Suspension is heated to boiling point at the rate 10-20 degrees/h at stirring. Precipitate of titanium hydroxide applied on CaSO₄ and SiO₂ is separated, washed out and subjected for salt treatment. Salt treatment is carried out with modifying suspension. Suspension is obtained from liquid phase after thermal treatment where apatite and then nepheline are added to residual content of P₂O₅ in mixture 1-4 wt.- %. Suspension is taken on the basis of T : V_c = 1 : (1.0-1.5). Salt treatment is carried out at stirring and then ammonia is added to pH = 4.5. Precipitate is filtered off and calcined. Extraction of TiO₂ is 92-95%, content of water-soluble impurities is 0.92-2%, brightening ability is 400-450 conventional units. Invention can be used in producing pigments in leather, paint and varnish industry and in paper production. EFFECT: improved method of processing. 3 ex