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. 23, 1991
Filed:
Sep. 17, 1990
Applicant:
Inventors:
Francinet Cailly, Paris, FR;
Yves Mottot, Tremblay en France, FR;
Assignee:
Rhone-Poulenc Chimie, Courbevoie, FR;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C01F / ;
U.S. Cl.
CPC ...
423 211 ; 423555 ;
Abstract
Rare earth values are recovered from gypsum starting material by (i) dissolving such gypsum in water and separating therefrom the water-insoluble fractions which contain the rare earth elements (ii) treating such insoluble fractions with a solution of carbonate ions, (iii) next digesting the insoluble fractions thus treated with a mineral acid and converting at least the rear earth values into water-soluble salts thereof, and (iv) recovering such rear earth values from the medium of digestion.