Anglo-American Clays Corporation

Alan J Nott

A method for brightening a natural dolomitic ore by removal of discoloring contaminants. The ore is crushed and formed into an aqueous slurry, which slurry is then coarse-milled to produce a product wherein no more than 1% of the particulate matter is +325 mesh. This coarse-milled product is then subjected to a further, wet-milling step, to alter the particulate such that at least 70% of the particles are less than 2 microns, E.S.D. thereby liberating substantial quantities of the discoloring contaminants. The liberated impurities are thereupon separated by subjecting the slurry to a high intensity magnetic field.

Brightening of natural dolomitic ores

A method for brightening a kaolin clay wherein an aqueous dispersion is initially formed of said clay, which dispersion is blunged and conditioned and the resultant slurry thereupon subjected to a froth flotation treatment to remove titaniferous impurities. The purified product from the froth flotation treatment is thereupon subjected to magnetic separation by passing such product through a slurry-pervious ferromagnetic matrix positioned in a high intensity magnetic field, which results in substantial, additional brightening of the clay.

Method for improving clay brightness utilizing magnetic separation

A method for improving the brightness and whiteness of kaolin clays or the like. An aqueous slurry of the clay is initially treated with a solution of sodium borohydride and sodium hydroxide at a pH of above 7.0 up to about 10.0. Sulphur dioxide is then bubbled through the slurry or otherwise brought into contact with same, the pH being permitted to attain a value of between 6.0 and 7.0. The pH may thereupon be adjusted to between 2.5 and 4.0 with an acid, at which pH the leach reaction may occur; or the application of gaseous sulphur dioxide may be continued to yield a pH of the indicated 2.5 to 4.0 range.

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Tennille, GA, United States of America

Alan J Nott