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:
Apr. 25, 1978
Filed:
Aug. 29, 1975
Erhart K Drechsel, Houston, TX (US);
Pennzoil Company, Shreveport, LA (US);
Abstract
A method is disclosed for the acidulation of phosphate rock and the production of substantially pure alkali metal phosphates, calcium phosphates, and phosphoric acid which are essentially free of fluorides and recovery of the fluorine values from the starting phosphate rock in useful form. The steps of the method comprise initial acidulation of phosphate rock with a phosphoric acid solution containing sufficient alkali metal values to provide R.sub.2 O in the system, where R is alkali metal, to solubilize the phosphates and form an insoluble precipitate comprising a mixture of impurities, sand (SiO.sub.2) and the fluorides, from which the fluorides can be recovered in usable form. In preferred embodiments, after removal of the precipitate containing the fluorides, a portion of the solution of phosphoric acid and calcium phosphate is reacted with sulfuric acid and RHSO.sub.4 or R.sub.2 SO.sub.4 where R is alkali metal, to form a solution of RH.sub.2 PO.sub.4 and phosphoric acid and at least a portion of the RH.sub.2 PO.sub.4 and phosphoric acid solution is recycled to the initial acidulation to provide the R.sub.2 O and phosphoric acid makeup. The remainder of the solution of calcium phosphate and phosphoric acid may be further processed for recovery of useful products such as monocalcium phosphate and/or dicalcium phosphate, phosphoric acid, alkali metal phosphates, and calcium sulfate.