GB1026691A - Improvements in or relating to the treatment of titanium bearing ores - Google Patents

Abstract

Metallic iron is obtained by heating a titanium bearing ore containing iron with a reducing agent in such a manner that a liquid slag is not produced, and where prior to the completion of the reduction at least one compound of magnesium in an amount from 0.25-10% by wt. of ore calculated as MgO is added. The reduction may be carried out in two stages, metallic iron being removed after each stage with the magnesium compound(s) being added after the first removal. The reduction may be effected by heating the ore at 800-1300 DEG C with coke or at 700-1000 DEG C with a gaseous reducing agent e.g. Co or H2. In order to facilitate the separation of metallic iron from the reduced ore, conventional conditioning agents e.g. CaF2, boron compounds, may be added. The metallic iron may be removed by leaching with acid, by electromechanical methods or by submerging the ore in an acidic medium, agitating, and contacting the ore with an oxidising gas.ALSO:Titanium dioxide is prepared from a titanium-and-iron-containin ore, e.g. ilmenite or leuccoxene, by heating the ore with a reducing agent in such a way that, without producing a liquid slag, at least part of the iron content is reduced to metallic iron, removing the latter, sulphating the enriched ore to bring the titanium and residual iron into water-soluble form, dissolving the latter in an aqueous medium, and precipitating titanium dioxide from the resulting solution by hydrolysis. The process is characterized by the addition of at least one magnesium compound in an amount from 0.25-10% by weight based on the ore, and calculated as MgO, to the ore prior to the completion of reduction. A water-insoluble magnesium compound, e.g. magnesite, dolomite, MgO or MgSiO4, may be admixed with the ore or a solution of a water-soluble magnesium compound, e.g. the chloride or a double salt, e.g. MgCl2.KCl.6H2O, may be added to the ore. In the latter instance, the wet ore is dried at 50-150 DEG C. before reduction. The reduction may, however, be carried out in two stages, metallic iron being removed after each stage and the magnesium compound(s) being added after the first removal. The reduction may be effected by heating the ore at 800-1300 DEG C. with coke or at 700-1000 DEG C. with a gaseous reducing agent, e.g. CO or H2. Metallic iron may be removed by leaching with acid or by electro-mechanical methods. In order to facilitate the removal of iron, a conditioning agent, e.g. CaF2, a boron compound (e.g. boron oxide or boric acid), a mixture of a boron compound with a phosphate-containing material or a sodium compound (e.g. NaOH or NaCl) may be added. In order to produce TiO2 pigment, the TiO2: Fe ratio of the solution to be hydrolysed is adjusted to 2: 1 to 6: 1 prior to precipitation of titanium dioxide. The desired ratio can be achieved by crystallizing out iron sulphate or by adding more ore to the reduced ore prior to sulphation.