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. 25, 1997
Filed:
Nov. 21, 1994
Donald Kendall Drummond, Glenmoore, PA (US);
Minerals Technologies Inc., New York, NY (US);
Abstract
A method for lowering the iron content of calcium carbonate is disclosed. The method involves addition of an iron chelating agent to an aqueous calcium carbonate slurry, reducing the pH of the aqueous calcium carbonate by employing carbon dioxide containing gas, while maintaining the aqueous calcium carbonate slurry at an elevated temperature. The slurry is stirred, filtered, washed and dried. The calcium carbonate product resulting from the process of the present invention has a reduced iron content. Calcium carbonate produced according to the method of this invention is particularly suitable for use as food or pharmaceutical additives and may also be useful as a filler in papermaking processes or as additives in plastic products.