Process for the production of titanium dioxide using aqueous fluoride

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.