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US 4,288,418 AGranted
Process for manufacturing titanium dioxide
AssigneeNL Industries, Inc.
InventorsBrian R. Davis, Joseph A. Rahm
Life of this patent
Estimating the term…
Abstract
A process is provided for the manufacture of titanium dioxide pigment wherein excess ilmenite ore is reacted with dilute sulfuric acid having a concentration of between about 25% and about 60% by weight and in preferably at least two stages wherein the first stage is maintained at a temperature up to about 140.degree. C. and the second stage is conducted at a lower temperature (than the first stage) which is below about 100.degree. C. to provide a salt solution of titanium and iron. Thereafter, the titanium is hydrolyzed to provide titanium dioxide hydrate accompanied by recycling the spent acid from the hydrolysis for reaction with the ilmenite ore charged to the process. The titanium hydrate is calcined to provide titanium dioxide pigment.
Claims12
A process for producing titanium dioxide pigment which comprises
- (1) reacting
- ilmenite, in an amount between 10% and 400% in excess of the stoichiometric amount of ilmenite necessary to react with sulfuric acid to provide titanyl sulphate, and
- dilute sulfuric acid solution having a concentration between about 25% and about 60% by weight, based upon the total weight of said solution,
- at a temperature below about 140.degree. C.;
- (2) cooling the resulting reaction solution to a temperature below about 100.degree. C.;
- (3) removing iron sulphate from said reaction solution to provide a titanyl sulphate solution;
- (4) hydrolyzing said titanyl sulphate solution to provide a hydrate of titanium dioxide;
- (5) calcining said hydrate of titanium dioxide to provide titanium dioxide and (6) recovering titanium dioxide.
5 more elements
A continuous process for producing titanium dioxide pigment which comprises:
- (1) reacting (a) ilmenite, in an amount between 10% and 400% in excess of the stoichiometric amount of ilmenite necessary to react with sulfuric acid to provide titanyl sulphate, and (b) dilute sulfuric acid solution having a concentration between about 25% and about 60% by weight, based upon the total weight of said solution, at a temperature below about 140.degree. C.;
- (2) cooling the resulting reaction mixture from (1) to a temperature below about 100.degree. C. in a second reaction vessel;
- (3) separating unreacted ilmenite from the reaction mixture of (2) to provide a solution of iron sulphate and titanyl sulphate and recycling said unreacted ilmenite to (1);
- (4) removing iron sulphate from said solution of iron sulphate and titanyl sulphate to provide a solution of titanyl sulphate;
- (5) hydrolyzing said titanyl sulphate solution from (4) to provide a titanium dioxide hydrate, and recycling spent sulfuric acid to (1);
- (6) calcining said titanium dioxide;
- and
- (7) recovering titanium dioxide.
5 more elements
A continuous process for producing titanium dioxide pigment which comprises:
- (1) reacting (a) ilmenite, in an amount between 10% and 400% in excess of the stoichiometric amount of ilmenite necessary to react with sulphuric acid to provide titanyl sulphate, and (b) dilute sulfuric acid solution having a concentration between about 25% and about 60% by weight, based upon the total weight of said solution, in a first reaction vessel at a temperature below about 140.degree. C. to provide a reaction solution having a ratio of active acid to titanium dioxide of about 3.0;
- (2) continuously transporting said reaction solution from said first reaction vessel to a second reaction vessel, and recycling a portion of unreacted ilmenite to (1);
- (3) continuing said reaction of ilmenite and dilute sulfuric acid in said second reaction vessel at a temperature below about 90.degree. C. to provide a reaction solution having a ratio of active acid to titanium dioxide of about 2.0;
- (4) separating unreacted ilmenite from the reaction mixture of (3) to provide a solution of iron sulphate and titanyl sulphate, and recycling said unreacted ilmenite to (3) or (1);
- (5) cooling the reaction solution of (4) to crystallize iron sulphate;
- (6) filtering the reaction mixture of (5) to remove iron sulphate crystals and provide a solution of titanyl sulphate;
- (7) hydrolyzing said solution of titanyl sulphate from (6) to provide a titanium dioxide hydrate, and recycling spent sulfuric acid to (1);
- (8) calcining said titanium dioxide hydrate from (7) to provide titanium dioxide;
- and
- (9) recovering titanium dioxide.
7 more elements
A continuous process for producing titanium dioxide pigment which comprises:
- (1) reacting (a) ilmenite, in an amount between 10% and 400% in excess of the stoichiometric amount of ilmenite necessary to react with sulfuric acid to provide titanyl sulphate, and (b) dilute sulfuric acid solution having a concentration between about 25% and about 60% by weight, based upon the total weight of said solution, in a first reaction vessel at a temperature below about 140.degree. C. to provide a reaction solution having a ratio of active acid to titanium dioxide of between about 3.0 and about 7.0;
- (2) continuously transporting said reaction solution from said first reaction vessel to a second reaction vessel, and recycling a portion of unreacted ilmenite to (1);
- (3) continuing said reaction of ilmenite and dilute sulfuric acid in said second reaction vessel at a temperature of about 100.degree. C. to provide a reaction solution having a ratio of active acid to titanium dioxide of between about 2.4 and about 3.5;
- (4) continuously transporting said reaction solution from said second reaction vessel to a third reaction vessel and recycling a portion of unreacted ilmenite to (3);
- (5) continuing said reaction of ilmenite and dilute sulfuric acid in said third reaction vessel at a temperature of about 80.degree. C. to provide a reaction solution having a ratio of active acid to titanium dioxide of about 2.0;
- (6) separating unreacted ilmenite from the reaction mixture of (5) to provide a solution of iron sulphate and titanyl sulphate, and recycling said unreacted ilmenite to (5) or (1);
- (7) cooling the reaction solution of (5) to crystallize iron sulphate;
- (8) filtering the reaction mixture of (7) to remove iron sulphate crystals and provide a solution of titanyl sulphate;
- (9) hydrolyzing said solution of titanyl sulphate from (8) to provide a titanium dioxide hydrate and recycling spent sulfuric acid to (1);
- (10) calcining said titanium dioxide hydrate from (9) to provide titanium dioxide;
- and
- (11) recovering titanium dioxide.
9 more elements
Dependencies are inferred from the claim text.