초록 ▼

A process for beneficiating a crude kaolinitic clay mineral to produce a clay filler for use in papermaking to improve the brightness, the color characteristics and the light scattering efficiency of the paper product. The crude kaolin clay is blunged with water containing a dispersing agent consist

A process for beneficiating a crude kaolinitic clay mineral to produce a clay filler for use in papermaking to improve the brightness, the color characteristics and the light scattering efficiency of the paper product. The crude kaolin clay is blunged with water containing a dispersing agent consisting of a blend of from about 20% to about 50% by weight of a water-soluble carbonate, about 20% to about 50% by weight of a water-soluble polyacrylate, and from 0% to about 60% by weight of a water-soluble anionic phosphate, to form a high solids fluid aqueous clay suspension having an acidic pH. This clay suspension is then fractionated to reduce the percentage of particles therein larger than 45 microns to not more than 0.2% by weight. The fractionated clay suspension is treated with an alkaline leaching solution containing a reducing agent effective in converting ferric ions to ferrous ions. The treated clay suspension has a solids content of at least 65% by weight, a low grit content, an acid pH, and a brightness of at least 84, and is suitable without further dewatering for use as a clay filler in making paper.

대표청구항 ▼

A process for treating a crude kaolinitic clay mineral comprising: a. forming a fluid aqueous suspension of crude kaolinitic clay mineral, said suspension having a solids content of at least about 65% by weight and an acid pH of at least about 5.5, said suspension containing a dispersing agent compr

A process for treating a crude kaolinitic clay mineral comprising: a. forming a fluid aqueous suspension of crude kaolinitic clay mineral, said suspension having a solids content of at least about 65% by weight and an acid pH of at least about 5.5, said suspension containing a dispersing agent comprising from about 20% to about 50% by weight of a water-soluble carbonate, from about 20% to about 50% by weight of a water-soluble orgainic polyarylate, and from 0% to about 60% by weight of a water-soluble anionic phosphate; b. subjecting said suspension to a degritting process to reduce the percentage by weight of the particles in said suspension larger than 45 microns to not more than 0.2% by weight; and c. treating said suspension having a solids content of at least about 65% by weight and an acid pH with an aqueous leaching solution containing a water-soluble reducing agent and having an alkaline pH for a time sufficient to increase the brightness and improve the coloration of the clay mineral therein, said suspension after treatment with said leaching solution having a solids content of at least about 65% by weight.