Kaolin pigments and methods of making the same

1. A method of processing kaolin, comprising sequentially:

providing a kaolin crude comprising higher amount of gray kaolin and a lower amount of white kaolin;

degritting the kaolin crude;

subject the degritted kaolin crude to flotation to provide a kaolin having reduced titania content;

ozonating the kaolin having reduced titania content;

centrifuging the kaolin at high speeds to provide a coarse stream and fine stream, the course stream comprising kaolin wherein at least about 70% by weight has a size of 2 microns or less, the fine stream comprising kaolin wherein at least about 80% by weight has a size of 1 micron or less;

refining the coarse stream into a coarse engineered kaolin pigment, wherein the coarse engineered kaolin pigment has a surface area from about 15 to about 19 m 2 /g and about 0.75% by weight or less of titania; and

refining the fine stream into a fine glossing kaolin pigment;

with the proviso that the method does not comprise fractioning the kaolin.

2. The method of claim 1 , wherein centrifuging at high speeds involves using at “g” forces from about 2,000 to about 10,000.

3. The method of claim 1 , wherein the kaolin crude comprises at least about 70% of gray kaolin and less than about 30% of white kaolin.

4. The method of claim 1 , wherein flotation reduces the titania content of the kaolin to less than about 1% by weight.

5. The method of claim 1 , wherein ozonating comprises contacting from about 0.1 to about 20 pounds of ozone per ton of kaolin.

6. The method of claim 1 , further comprising centrifuging the kaolin at low speeds before flotation or after centrifuging the kaolin at high speeds.

7. The method of claim 6 , wherein centrifuging at low speeds involves using “g” forces from about 200 to about 2,000.

8. The method of claim 1 , wherein refining the fine stream comprises at least two of delamination, bleaching, filtering, and spray drying.

9. The method of claim 1 , wherein refining the fine stream comprises at least two of delamination, bleaching, filtering, and drying.

10. A method of processing kaolin, comprising sequentially:

providing a kaolin crude comprising at least about 60% of gray kaolin and less than about 40% of white kaolin;

degritting the kaolin crude;

subjecting the degritted kaolin crude to flotation to provide a kaolin having reduced titania content;

ozonating the kaolin having reduced titania content;

centrifuging the kaolin at high speeds to provide a coarse stream and find stream, the coarse stream comprising kaolin wherein at least about 80% by weight has a size of 2 microns or less, the fine stream comprising kaolin wherein at least about 80% by weight has a size of 1 micron or less; and

bleaching, filtering, and spray drying the coarse stream to provide a coarse engineered kaolin pigment, wherein the coarse engineered kaolin pigment has a surface area from about 15 to about 19 m 2 /g and about 0.75% by weight or less of titania;

with the proviso that the method does not comprise fractioning the kaolin.

11. The method of claim 10 , further comprising combining the fine stream with a white kaolin to provide a kaolin pigment having a brightness of at least about 90.

12. The method of claim 10 , wherein degritting the kaolin crude comprises passing the kaolin crude through at 325 mesh sieve or smaller.

13. The method of claim 10 , wherein flotation comprises one of froth flotation, ultraflotation, and TREP flotation.

14. The method of claim 10 , further comprising refining the fine stream into a line glossing kaolin pigment.

15. The method of claim 1 , wherein flotation is conducted using a solids contents from about 10% to about 50%, a pH from about 5 to about 11, and at a temperature from about 10° C. to about 90° C.

16. The method of claim 10 , wherein flotation is conducted using a solids content from about 20% to about 40%, a pH from about 6 to about 10, and at a temperature from about 20° C. to about 60° C.

17. The method of claim 10 , wherein flotation reduces the titania content of the kaolin to less than about 0.7% by weight and iron oxide to less than about 1.25% by weight.

18. The method of claim 1 , wherein the coarse engineered kaolin pigment has at least about 96% by weight of the particles having a size of 5 microns or less, at least about 90% by weight of the particles having a size of 2 microns or less, at least about 25% by weight of the particles having a size of 0.3 microns or less, a surface area from about 15 to about 19 m 2/ g, about 0.75% by weight or less of titania, about 1.25% by weight or less of iron oxide, and a brightness of about 87.5 or more; and the fine glossing kaolin pigment has at least about 90% by weight of the particles having a size of 1 micron or less, at least about 97% by weight of the particles having a size of 2 microns or less, at least about 98% by weight of the particles having a size of 5 microns or less, from about 65% to about 80% of the particles having a size of 0.3 microns or less, a surface area from about 22 to about 29 m 2/ g, about 0.5% by weight or less of titania, about 1.25% by weight or less of iron oxide, brightness of about 90 or more, and high shear viscosity of about 15 dynes/4400 rpm or less at 70% solids.

19. The method of claim 10 , wherein the coarse engineered kaolin pigment has at least about 97% by weight of the particles having a size of 5 microns or less, at least about 95% by weight of the particles having a size of 2 microns or less, from about 26% to about 33% by weight of the particles having a size of 0.3 microns or less, a surface area from about 16 to about 19 m 2/ g, about 0.5% by weight or less of titania, about 1% by weight or less of iron oxide, and a brightness of about 89 or more; and the fine glossing kaolin pigment has at least about 95% by weight of the particles having a size of 1 micron or less, at least about 99% by weight of the particles having a size of 2 microns or less, at least about 99.9% by weight of the particles having a size of 5 microns or less, from about 70% to about 75% of the particles having a size of 0.3 microns or less, a surface area from about 23 to about 28 m/g, about 0.4% by weight or less of titania, about 1% by weight or less of iron oxide, brightness of about 91 or more, and high shear viscosity of about 10 dynes/4400 rpm or less at 70% solids.