US4944936A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Titanium dioxide with high purity and uniform particle size and method therefore
Assignee: Kemira Inc
•
Filing: 1988-07-29
•
Granted: 1990-07-31
•
Expires: 2008-07-29
Abstract
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.
Inventors
- 👤 Earl R. Lawhorne
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:59
CPC Classifications
C; C01; C01G; C01G23/00; C01G23/04; C01G23/047; C01G23/053; C01G23/0536; C01G23/0538; C01P; C01P2004/00; C01P2004/51; C01P2004/60; C01P2004/61; C01P2006/00; C01P2006/11; C01P2006/12; C01P2006/20; C01P2006/80
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
171 words
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° 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 μm to about 40 μm 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.
Claim 2
Independent Claim
171 words
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° 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 μm to about 40 μm 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.
Claim 3
Dependent Claim
32 words
A method as claimed in claim 1, including the step of introducing hydrogen sulfide into the titanium oxychloride solution to remove impurities thereon prior to said addition to water in step (b).
Claim 4
Dependent Claim
34 words
A method as claimed in claim 1, wherein the amount of seed suspension added in step (d) is from about 0.1 to about 5.0% by weight based on titanium dioxide concentration in said solution.
Claim 5
Dependent Claim
22 words
A method as claimed in claim 1, wherein said boiling step has a duration of from about 1 to about 7 hours.
Claim 6
Dependent Claim
36 words
A method as claimed in claim 1 wherein the calcination step is carried out at a temperature of from about 600 to about 1000° C. for a period of from about 0.5 to about 3.0 hours.
Claim 7
Dependent Claim
31 words
A method as claimed in claim 1, wherein the concentration of said titanium oxychloride solution is from about 100 to about 400 g of titanium dioxide equivalent per liter of solution.
Claim 8
Dependent Claim
44 words
A method as claimed in claim 1, wherein the seed suspension provided in step (c) is prepared separately by neutralizing a portion of the titanium oxychloride solution with ammonium hydroxide and then stabilized by heating to between about 70° C. and about 80° C.
Claim 9
Independent Claim
211 words
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° 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 μm to about 40 μm 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.
Claim 10
Independent Claim
211 words
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° 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 μm to about 40 μm 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.
Claim 11
Dependent Claim
24 words
A method as claimed in claim 1, wherein the final product of free flowing, anhydrous, rutile titanium dioxide has a purity greater than 99.5%.
Claim 12
Dependent Claim
24 words
A method as claimed in claim 8, wherein the final product of free flowing, anhydrous, rutile titanium dioxide has a purity greater than 99.5%.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-30 | 1994-01-29 | 1994-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-30 | 1998-01-29 | 1998-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-30 | 2002-01-29 | 2002-07-31 | $7700.00 | Window Closed / Lapsed |