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. 29, 1977
Filed:
Jun. 15, 1976
John B Sardisco, Shreveport, LA (US);
Erhart Karl Drechsel, Houston, TX (US);
Pennzoil Company, Shreveport, LA (US);
Abstract
In a process for the reaction of phosphate rock and sulfuric acid in the presence of potassium ion to form a mixture of phosphoric acid and a precipitated gypsum wherein the presence of the potassium ion causes precipitation of fluorides from the phosphate rock as potassium silicofluoride as a coprecipitate with the gypsum, and the phosphoric acid is separated from the gypsum slurry, the potassium silicofluoride is separated from the gypsum by extraction with phosphoric acid which may contain from 0-25 weight percent of sulfuric acid based on the amount of gypsum to be extracted or such phosphoric acid which may contain some fluorine. This extraction procedure provides a substantially fluoride-free gypsum product and an extraction solution containing recoverable potassium silicofluoride.