Abstract: It is disclosed a process for the production of titanium dioxide comprising the following steps: (a) a titanium ore containing iron, preferably ilmenite, is reacted with an aqueous NH4F solution; (b) the aqueous suspension thus obtained is filtered with consequent separation of a sludge fraction, which contains ammonium fluoroferrates, and a filtrate fraction, which contains ammonium fluorotitanates; (c) the filtrate fraction thus obtained is subjected to an hydrolysis reaction; (d) the thus-obtained solid component is subjected to a thermal hydrolysis reaction. The plant and the reactors for performing the above process are also disclosed.

Abstract: A process is described for the production of titanium dioxide by the treatment with ammonium fluoride of titanium ores containing iron; the process comprises the following steps: (a) the titanium ore containing iron is reacted with an aqueous NH4F and/or NH4HF2 solution; (b) the aqueous dispersion thus obtained is filtered with consequent separation of a solid residue and an aqueous solution containing titanium salts; (c) the aqueous solution thus obtained is subjected to hydrolysis, the hydrolysis comprising a first stage at pH 7.0-8.5 and a second stage at pH 10.0-13.0; (d) the aqueous dispersion thus obtained is filtered and the solid residue is subjected to pyrohydrolysis, the pyrohydrolysis comprising a first stage at a maximum temperature of 450° C. and a second stage at a maximum temperature of 1000° C.

Abstract: A process is described for the production of titanium dioxide by the treatment with ammonium fluoride of titanium ores containing iron; the process comprises the following steps: (a) the titanium ore containing iron is reacted with an aqueous NH4F and/or NH4HF2 solution; (b) the aqueous dispersion thus obtained is filtered with consequent separation of a solid residue and an aqueous solution containing titanium salts; (c) the aqueous solution thus obtained is subjected to hydrolysis, the hydrolysis comprising a first stage at pH 7.0-8.5 and a second stage at pH 10.0-13.0; (d) the aqueous dispersion thus obtained is filtered and the solid residue is subjected to pyrohydrolysis, the pyrohydrolysis comprising a first stage at a maximum temperature of 450° C. and a second stage at a maximum temperature of 1000° C.