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US 4,944,936 AGranted
Titanium dioxide with high purity and uniform particle size and method therefore
AssigneeKemira Oy
InventorEarl R. Lawhorne
Life of this patent
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Abstract
High purity titanium dioxide having uniform controlled particle size and method therefor. Titanium tetrachloride is mixed with water to form titanium oxychloride, which in turn is precipitated from aqueous solution to form titanium dioxide.
Claims10
A method for producing uniform particle size titanium dioxide, comprising the steps of:
- (a) providing a quantity of titanium tetrachloride;
- (b) adding said titanium tetrachloride to water to form a titanium oxychloride solution having a molar ratio of chloride to titanium of from about 4.0 to about 2.5;
- (c) providing a seed suspension of titanium dioxide;
- (d) adding said seed suspension to said titanium oxychloride solution;
- (e) boiling said solution for a period sufficient to effect precipitation of titanium hydrolysate;
- (f) recovering the precipitated titanium hydrolysate at a temperature of less than or equal to about 110.degree. C.;
- (g) calcining said precipitated titanium hydrolysate to form free flowing, anhydrous, rutile titanium dioxide having a mean particle size substantially within the range of from about 10 .mu.m to about 40 .mu.m as the final product;
- and
- (h) controlling the rate of precipitation of titanium dioxide and the final product particle size by varying the concentration of the titanium oxychloride solution or the amount of seed added by way of said seed suspension.
6 more elements
A method for producing uniform particle size titanium dioxide, comprising the steps of:
- (a) providing a quantity of titanium tetrachloride;
- (b) adding said titanium tetrachloride to water to form a titanium oxychloride solution containing the equivalent of from about 100 grams to about 400 grams of titanium dioxide per liter of solution, and whose molar ratio of chloride to titanium is from about 4.0 to about 2.5;
- (c) providing a seed suspension of titanium hydrolysate containing the equivalent of from about 0.1 to about 5.0% titanium dioxide by weight in said seed solution;
- (d) adding said seed suspension to said titanium oxychloride solution;
- (e) boiling said solution for a period sufficient to effect precipitation of titanium hydrolysate;
- (f) recovering the precipitated titanium hydrolysate at a temperature of less than or equal to about 110.degree. C.;
- (g) calcining said precipitated titanium hydrolysate to form a free flowing, anhydrous, rutile titanium dioxide having a mean particle size substantially within the range of from about 10 .mu.m to about 40 .mu.m as the final product;
- and
- (h) controlling the rate of precipitation of titanium dioxide and the final product particle size by varying the concentration of the titanium oxychloride solution or the amount of seed added by way of said seed suspension or both.
6 more elements
Dependencies are inferred from the claim text.