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:
May. 31, 1977
Filed:
Dec. 11, 1975
Chemie Linz Aktiengesellschaft, Linz, OE;
Abstract
A process for purifying waste gypsum from the wet phosphoric acid process to a maximum fluorine content of 0.25 % by weight based on the anhydride, which comprises adding active silicic acid in two portions during the course of the phosphoric acid process, wherein at least half the total amount of silicic acid added is added during the decomposition of the crude phosphate and the remainder is added after the end of the decomposition but before the waste gypsum is filtered off, and the waste gypsum, after it has been filtered, is made into a suspension with water, separated from the liquid phase and dried.
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