The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 06, 1981
Filed:
Apr. 02, 1979
Herbert I Lewis, Wrens, GA (US);
Anthony D McConnell, Sandersville, GA (US);
William M Price, St. Austell, GB;
Anglo-American Clays Corporation, Sandersville, GA (US);
Abstract
A method is disclosed for processing a natural calcitic ore to yield a finely divided calcium carbonate particulate of very high brightness characteristics. The natural calcitic ore is initially coarse-milled to produce a product wherein no more than 5% by weight of the particulate is +325 mesh, and no more than 35% by weight of the particles are of less than 2 microns E.S.D. This coarse-milled product is then subjected as an aqueous slurry containing less than 40% and preferably less than 30% solids by weight, to a froth flotation, which separates with the froth the relatively coarse colorbodies liberated in the initial grinding. Preferable compositions for use in the froth flotation comprise 1-substituted-2-alkyl imidazolines or the salt derivatives thereof, with such compounds being utilized in admixture with a substantially non-polar aliphatic compound having from 10 to 20 carbon atoms in its longest straight chain. The purified underflow from the flotation step is dewatered to at least 60% solids by weight, and is wet-milled, as for example in a sand mill, to yield an output product wherein at least 80% by weight of the resultant particulate has an E.S.D. of less than 2 microns, the product being further characterized by a brightness of at least 95 on the G.E. scale.