Method for producing particulate titanium oxides

Claim 1

A method for producing particulate titanium dioxide from titanium tetrahalides comprising the steps of: forming a first aqueous solution comprised of a titanium tetrahalide and sulfuric acid and heating said first aqueous solution to a sufficiently elevated temperature whereby said titanium tetrahalide and said sulfuric acid react to produce in said first solution a dissolved intermediate product comprising titanyl sulfate and to produce a byproduct hydrogen halide gas; continuing the heating of said first aqueous solution at an elevated temperature and in the presence of a quantity of a previously prepared particulate titanyl sulfate whereby said dissolved titanyl sulfate intermediate is caused to crystallize from said first aqueous solution; separating said crystallized titanyl sulfate intermediate from said first aqueous solution to produce a wet filter cake comprising residual mother liquor and said crystallized titanyl sulfate intermediate; forming a second aqueous solution comprised of said filter cake dissolved in a quantity of an aqueous solvent medium, said quantity being sufficient to effect dissolution of the crystallized titanyl sulfate intermediate contained in said filter cake, but insufficient to effect hydrolysis thereof; subjecting said dissolved crystallized titanyl sulfate intermediate to hydrolysis by combining said second aqueous solution with a further quantity of said aqueous solvent medium heated to an elevated temperature whereby said dissolved crystallized titanyl sulfate intermediate contained in said second solution is hydrolyzed to produce a particulate amorphous titanium dioxide intermediate; separating said particulate amorphous titanium dioxide intermediate to provide a particulate crystalline titanium dioxide product and recovering said crystalline product substantially as produced.

Claim 2

A method for producing particulate titanium dioxide from titanium tetrahalides comprising the steps of: forming a first aqueous solution comprised of a titanium tetrahalide and sulfuric acid and heating said first aqueous solution to a sufficiently elevated temperature whereby said titanium tetrahalide and said sulfuric acid react to produce in said first solution a dissolved intermediate product comprising titanyl sulfate and to produce a byproduct hydrogen halide gas; continuing the heating of said first aqueous solution at an elevated temperature and in the presence of a quantity of a previously prepared particulate titanyl sulfate whereby said dissolved titanyl sulfate intermediate is caused to crystallize from said first aqueous solution; separating said crystallized titanyl sulfate intermediate from said first aqueous solution to produce a wet filter cake comprising residual mother liquor and said crystallized titanyl sulfate intermediate; forming a second aqueous solution comprised of said filter cake dissolved in a quantity of an aqueous solvent medium, said quantity being sufficient to effect dissolution of the crystallized titanyl sulfate intermediate contained in said filter cake, but insufficient to effect hydrolysis thereof; subjecting said dissolved crystallized titanyl sulfate intermediate to hydrolysis by combining said second aqueous solution with a further quantity of said aqueous solvent medium heated to an elevated temperature whereby said dissolved crystallized titanyl sulfate intermediate contained in said second solution is hydrolyzed to produce a particulate amorphous titanium dioxide intermediate; separating said particulate amorphous titanium dioxide intermediate to provide a particulate crystalline titanium dioxide product and recovering said crystalline product substantially as produced.