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:
Jun. 08, 1999
Filed:
Jul. 13, 1998
Walter Vladimir Cicha, Pittsburgh, PA (US);
Donald Keith Swanson, Sommerville, NJ (US);
E. I. du Pont de Nemours and Company, Wilmington, DE (US);
Abstract
A process suitable for producing high purity alkaline earth fluoride product is disclosed which involves (a) mixing (i) MgO, CaO, BaO, Mg(OH).sub.2, Ca(OH).sub.2, and/or Ba(OH).sub.2, (ii) NaOH, KOH and/or NH.sub.4 OH, and (iii) water, to form an aqueous slurry having a temperature of at least 20.degree. C. and an aqueous phase pH of at least 13; (b) adding fluosilicic acid, optionally adding additional water and optionally adding additional NaOH, KOH and/or NH.sub.4 OH to the slurry of (a) at a rate which maintains an aqueous phase pH of 11 or above, and in an amount to provide a molar ratio of Si: (Mg, Ca, and Ba) of at least 1:3.3, a molar ratio of (Na, K, and NH.sub.4):Si of at least 2:1, and a molar ratio of water:Si of at least 20:1, and to obtain a precipitate comprising an alkaline earth fluoride (MgF.sub.2, CaF.sub.2 and/or BaF.sub.2), and an aqueous solution of a soluble silicon anionic compound; and (c) recovering the alkaline earth fluoride product.