Abstract Production of a hydrolysis solution used to form titanium oxyhydrate and in turn titanium dioxide pigments having a high degree of whiteness, by digesting titanium dioxide-containing raw material with sulfuric acid at a weight ratio of TiO2 to H2SO4 of about 1:1-20, crystallizing the digested titanium in the form of titanyl sulfate dihydrate by adjusting the acid concentration, separating and redissolving the crystals to form an aqueous hydrolysis solution, and separating the hydrolysis solution from any undissolved constitutents present, to permit subsequent hydrolysis of the titanium content in the hydrolysis solution to form titanium oxyhydrate, and recovery of the oxyhydrate thereby formed for producing in turn TiO2 pigment.
Process according to claim 1, wherein the titanium content in such hydrolysis solution, after separation from such undissolved constituents, is hydrolyzed to form titanium oxyhydrate and such oxyhydrate is recovered.
Claim 2
Dependent Claim
22 words
Process according to claim 2, wherein thehydrolyzing of said titanium content is carried out at a temperature substantially between about 50*-100* C.
Claim 3
Dependent Claim
27 words
Process according to claim 1, wherein the titanium-containing raw material is digested with about 45-55% by weight sulfuric acid at the boiling point of the digesting solution.
Claim 4
Dependent Claim
23 words
Process according to claim 4, wherein the digesting is carried out at a ratio by weight of TiO2 to H2SO4 of about 1:2-10.
Claim 5
Dependent Claim
19 words
Process according to claim 5, wherein the titanyl sulfate dihydrate is crystallized at a temperature of about 100*-130* C.
Claim 6
Dependent Claim
41 words
Process according to claim 6, wherein the titanyl sulfate dihydrate is crystallized by the further addition of acid to adjust the acid concentration such that on completion of the crystallization the acid concentration of the remaining solution is about 6-8 molar.
Claim 7
Dependent Claim
23 words
Process according to claim 1, wherein the crystallization of the titanium sulfate dihydrate is accelerated by inoculation with seed crystals of TiOSO4.2 H2O.