| 摘要 |
<p>The present invention relates to a process for obtaining titanium dioxide pigments, from a titanium-bearing raw material, which comprises the following operations: of using hydrochloric acid (HCl), to leach the titanium-bearing raw material, in 4 countercurrent stages, during which the set temperatures are 107°C in the first stage, 90°C in the second stage and 80°C in stages 3 and 4, wherein aluminium, magnesium, zinc or iron is added in powder form in the third or fourth countercurrent leaching stage, the mass of said addition being calculated on the basis of the stoichiometry of the reactions between the Fe(III) contained in the titanium raw material, followed by countercurrent washing, with water and in three stages, of the pulp originating from the leaching, wet grinding and dewatering of the washed pulp, filtering and drying of the filtered product and, lastly, micronization of the dry product. The metal-chloride-bearing liquor generated in the course of the leaching undergoes a three-stage evaporation process and is conveyed to a pyrohydrolysis operation, the hydrochloric acid being regenerated and recycled to the fourth stage of the leaching operation.</p> |
