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:
Jul. 02, 1991
Filed:
Jan. 25, 1990
Paul C Chieng, St. Louis, MO (US);
Vikram P Mehrotra, Terre Haute, IN (US);
Chin-Liang Chou, Ballwin, MO (US);
International Minerals & Chemical Corp., Northbrook, IL (US);
Abstract
A method of producing a high purity silica powder which can be fused to form transparent, bubble-free particles. An ammonium fluosilicate solution is purified preliminarily by removing colloidal-sized silica onto which impurities in the solution have been adsorbed. The high purity powder is produced by ammoniation of an unsaturated aqueous solution of ammonium fluosilicate. Silica powder produced is filtered, washed, and dried before fusion. Additional pre-fusion treatments such as washing, hydrothermal leaching, calcination, and a combination thereof, may be utilized to ensure that the concentration of volatile material is low.