Method of treating clay to improve its whiteness

A method of treating clay to remove therefrom titanium mineral impurities, said method comprising the steps of:

• (a) mixing said clay in the form of an aqueous slurry having a solids content of clay and said impurities of at least 20% by weight with a collector for the titanium mineral impurities, and an activator for the titanium mineral impurities comprising a water-soluble salt of a metal chosen from the alkaline earth metals and the heavy metals;
• (b) conditioning the aqueous clay slurry at a solids content of at least 20% by weight for a time sufficient to dissipate therein at least 25 horsepower hours of energy per ton of solids at a pH below 7;
• (c) mixing a polyacrylate salt deflocculant with the resulting conditioned aqueous clay slurry after conditioning;
• (d) subjecting the resulting mixture of conditioned aqueous slurry having a solids content of at least 20 wt. % and the polyacrylate salt deflocculant to an air flotation process by passing air bubbles upwardly through the conditioned aqueous slurry and removing titanium mineral impurities with the froth;
• and
• (e) recovering clay having a reduced titanium minerals impurities content.