TiO 2 based scrubbing granules, and methods of making and using such TiO 2 based scrubbing granules are described. TiO 2 -based scrubbing granules include granulated TiO 2 and about 0.5% to about 20% dry weight inorganic salt binder. Other TiO 2 based scrubbing granules include unsintered granulated TiO 2 and about 0.5% to about 20% dry weight inorganic salt binder. Inorganic salt binder include sodium aluminate. Methods of making TiO 2 based scrubbing granules include i) combining TiO 2 particles with inorganic salt binder to form TiO 2 -binder mixture comprising from about 0.5% to about 20% dry weight binder; ii) granulating the TiO 2 -binder mixture; and drying the granulated TiO 2 -binder mixture to form TiO 2 -based scrubbing granules. Methods of using such TiO 2 -based scrubbing granules include introducing TiO 2 -based scrubbing granules to remove adherent deposits on an inner surface of a reactor or heat exchanger during processes of forming TiO 2 particles and finishing the formed TiO 2 particles into finished pigment products.
1. A method of removing deposits on an inner surface of the heat exchanger comprising:
i. introducing TiCl 4 into a TiO 2 reaction zone of a reactor to form TiO 2 particles;
ii. introducing TiO 2 -based scrubbing granules into the reactor or a heat exchanger, thereby resulting in a TiO 2 product stream comprising the TiO 2 -based scrubbing granules and formed TiO 2 particles,
wherein TiO 2 -based scrubbing granules consist of:
a. granulated TiO 2 ; and
b. sodium aluminate binder comprising from about 0.5% to about 20% by dry weight of the TiO 2 -based scrubbing granules; and
wherein the introduced TiO 2 -based scrubbing granules are unsintered; and
iii. cooling the TiO 2 product stream via the heat exchanger,
wherein the TiO 2 -based scrubbing granules in the TiO 2 product stream removes deposits on an inner surface of the heat exchanger as the TiO 2 product stream comprising the TiO 2 -based scrubbing granules passes through the heat exchanger.
2. The method of claim 1 , further comprising recovering the cooled TiO 2 particles and TiO 2 -based scrubbing granules from the heat exchanger.
3. The method of claim 2 , further comprising finishing the recovered TiO 2 particles into finished TiO 2 pigment via a wet finishing process.
4. The method of claim 3 , comprising finishing the recovered TiO 2 particles by introducing the recovered TiO 2 particles and recovered TiO 2 -based scrubbing granules into a slurry tank to form the finished TiO 2 pigment.
5. The method of claim 3 , further comprising not removing the TiO 2 -based scrubbing granules from the finished TiO 2 pigment.
6. The method of claim 1 , further comprising introducing a nucleating agent to the TiO 2 reaction mixture before, during, or after the TiO 2 -based scrubbing granules are introduced.
7. The method of claim 6 , wherein the nucleating agent comprises a salt or halide of a group IA metal.
8. The method of claim 6 , wherein the nucleating agent is selected from the group consisting of potassium, cesium, and combinations thereof.
9. The method of claim 6 , wherein the nucleating agent is selected from a group consisting of KCl, CsCl, and combinations thereof.
10. The method of claim 1 , wherein the TiO 2 -scrubbing granules are free flowing.
11. The method of claim 1 , wherein the TiO 2 -based scrubbing granules are introduced in an amount in range from about 1% to 10% weight percent of the total TiO 2 production rate in the reactor.
12. TiO 2 -based scrubbing granules consisting of:
i. granulated TiO 2 ; and
ii. sodium aluminate binder comprising from about 0.5% to about 20% by dry weight of the TiO 2 -based scrubbing granules; and
wherein the TiO 2 -based scrubbing granules are unsintered.
13. TiO 2 -based scrubbing granules of claim 12 , wherein the TiO 2 -based scrubbing granules have an average size from about 1 mm to about 25 mm.
14. TiO 2 -based scrubbing granules consisting of:
i. granulated TiO 2 ;
ii. sodium aluminate binder comprising from about 0.5% to about 20% by dry weight of the TiO 2 -based scrubbing granules; and
iii. an inorganic metal salt.
15. TiO 2 -based scrubbing granules of claim 14 , wherein the inorganic metal salt is selected from the group consisting of sodium sulfate, sodium phosphate, sodium silicate, sodium chloride, sodium hexametaphosphate, aluminum sulfate, and combinations thereof.
16. TiO 2 -based scrubbing granules of claim 14 , wherein the TiO 2 -based scrubbing granules are unsintered.
17. TiO 2 -based scrubbing granules of claim 16 , wherein the TiO 2 -based scrubbing granules have an average size from about 1 mm to about 25 mm.
18. A method of removing deposits on an inner surface of the heat exchanger comprising:
i. introducing TiCl 4 into a TiO 2 reaction zone of a reactor to form TiO 2 particles;
ii. introducing TiO 2 -based scrubbing granules of claim 14 into the reactor or a heat exchanger, thereby resulting in a TiO 2 product stream comprising the TiO 2 -based scrubbing granules and formed TiO 2 particles; and
iii. cooling the TiO 2 product stream via the heat exchanger,
wherein the TiO 2 -based scrubbing granules in the TiO 2 product stream removes deposits on an inner surface of the heat exchanger as the TiO 2 product stream comprising the TiO 2 -based scrubbing granules passes through the heat exchanger.