US 12,139,775 B2
Process for purifying and concentrating rare earths from phosphogypsum
Hamid Mazouz, Casablanca (MA); Rachid Boulif, El Jadida (MA); and Essaid Bilal, Saint-Etienne (FR)
Assigned to OCP SA, (MA)
Appl. No. 17/279,932
Filed by OCP SA, Casablanca (MA)
PCT Filed Sep. 30, 2019, PCT No. PCT/MA2019/000008
§ 371(c)(1), (2) Date Mar. 25, 2021,
PCT Pub. No. WO2020/067856, PCT Pub. Date Apr. 2, 2020.
Claims priority of application No. 1858946 (FR), filed on Sep. 28, 2018.
Prior Publication US 2021/0388466 A1, Dec. 16, 2021
Int. Cl. C22B 59/00 (2006.01); C01F 17/10 (2020.01); C22B 3/06 (2006.01); C22B 3/08 (2006.01); C22B 3/44 (2006.01)
CPC C22B 59/00 (2013.01) [C01F 17/10 (2020.01); C22B 3/065 (2013.01); C22B 3/08 (2013.01); C22B 3/44 (2013.01)] 15 Claims
 
1. Process for purifying and concentrating rare earths contained in phosphogypsum comprising providing a phosphogypsum and further comprising the steps of:
a) leaching the phosphogypsum with a solution of one or more strong acid(s) selected from the group consisting of sulphuric acid, nitric acid and hydrochloric acid, in order to obtain a leaching mixture comprising a liquid phase formed by a leaching solution containing rare earths originating from the phosphogypsum and the leaching acid, and a solid phase comprising the phosphogypsum,
b) adding, to the phosphogypsum, an oxidising agent selected from the group consisting of sodium chlorate and potassium chlorate to promote passage of the rare earths from the phosphogypsum into the leaching solution, and a reducing agent selected from the group consisting of powder iron and metal zinc to reduce solubility of mineral impurities contained in the leaching solution in order to allow their passage from the leaching solution into the solid phase,
c) separating the liquid phase enriched in rare earths and depleted in mineral impurities, and the solid phase enriched in mineral impurities.