Process for the preparation of a concentrate of titanium dioxide from titanium dioxide containing raw materials

摘要

The raw materials are leached with dilute mineral acid at elevated temperature, and the residue is reduced with reducing agents and subsequently leached with dilute mineral acid at elevated temperature. To produce a high-grade TiO2 concentrate, with the use and simultaneous disposal of the thin acid waste product, a) the raw material is leached in the first leaching stage at a temperature from 160 to 180 DEG C under elevated pressure with thin acid and the TiO2 content of an intermediate concentrate is adjusted to about 60%, b) the intermediate concentrate is filtered off and reduced with a solid carbonaceous fuel, if appropriate after a preceding oxidation, c) the reduced product (b) is leached at temperatures between 60 and 180 DEG C and, if necessary, under elevated pressure with the thin acid filtrate from the first leaching stage with a complete consumption of the free sulphuric acid and the TiO2 content of the concentrate is adjusted to more than 80% and d) the iron sulphate heptahydrate in the filtrate is crystallised out. IMAGE