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:
Nov. 07, 2000
Filed:
Jul. 12, 1999
Gary Michael Freeman, Macon, GA (US);
John Mecaslin Harrison, Twiggs, CO (US);
Klaus A Lunden, Kokkedal, DK;
J. M. Huber Corporation, Edison, NJ (US);
Abstract
A method of significantly improving the brightness and shade properties of a high quality PCC product. The method includes providing a calcium containing feed source that contains discoloring impurities. The calcium containing feed source is formed into an aqueous slurry of calcium carbonate. Thereafter, the slurry is fine screened through a 325 mesh screen in order to yield a slurry of filler grade calcium carbonate. The filler grade calcium carbonate slurry is wet milled in order to liberate the discoloring impurities and reduce the median particle size of the calcium carbonate to less than 2 microns. The discoloring impurities are then magnetically separated from the milled calcium carbonate slurry by subjecting the slurry to a high intensity magnetic filed. After the magnetic separation step, the purified slurry may be de-watered to yield a dry powder; or alternatively, the slurry may be retained in aqueous form. In any event, the resultant calcium carbonate product has a median particle size of less than 2 microns and a TAPPI brightness of greater than 96.