Processes for producing high-brightness kaolin in high yields, and kaolin materials produced therefrom

摘要

The present disclosure teaches improved processes to produce high-brightness kaolins at high yields from various natural sources of crude kaolin. In some embodiments, a process for treating mined kaolin comprises: blunging kaolin material with water at high shear to form a slurry; introducing the slurry to one or more beneficiation units for flocculation of titania (e.g., anatase) and titania-associated impurities (e.g., iron); introducing a sodium silicate composition, or precursors thereof, to the beneficiation units, wherein the sodium silicate composition is characterized by a Na2O/SiO2 ratio selected from about 0.25 to about 2.5; and recovering a suspension comprising at least 70% of the kaolin clay. The selected sodium silicate composition enhances flocculation of the titania while maintaining dispersion of the kaolin clay in the slurry. One or more chemical leaching reactions generate a treated kaolin that is characterized by a brightness of about 90 or higher.

主权项

1. A process for treating mined kaolin, said process comprising:
(a) providing a kaolin material comprising kaolin clay and titania with titania-associated impurities, wherein said kaolin material has a crude brightness less than 90; (b) blunging said kaolin material with water at high shear to form a slurry; (c) introducing said slurry to one or more beneficiation units for flocculation of said titania and said titania-associated impurities; (d) introducing a sodium silicate composition, or precursors thereof, to said one or more beneficiation units, wherein said sodium silicate composition has a Na2O/SiO2 ratio of about 0.25 to about 2.5, and wherein said sodium silicate composition enhances flocculation of said titania while maintaining dispersion of said kaolin clay in said slurry; and (e) recovering a suspension comprising at least 70% of said kaolin clay and subjecting said suspension to one or more chemical leaching reactions to generate a treated kaolin that has a brightness of about 90 or higher.