CERIUM CONCENTRATE AND MIXED RARE-EARTH CHLORIDE BY THE OXIDATIVE DECOMPOSITION OF BASTNAESITE IN MOLTEN SODIUM-HYDROXIDE

Bastnaesite was treated in molten NaOH at 623-777 K for 10-60 min under atmosphere. Cerium(III) in the ore was easily oxidized 95 % or more within 30 min to give an oxidation product composed of solid solutions of CeO2-rich and CeO2-lean phases and Ce-free rare earth oxide phase. Simultaneously fluoride ion was removed 97 % or more. Cerium concentrate was prepared from the oxidation product by leaching with 0.1-3 M HCl solution. The yield of cerium concentrate and the CeO2 Content reached 55-57% and 70-72%, respectively. Mixed rare earth chloride is composed of about 90 % rare earth chloride and 10 % alkaline earth chloride, and the contents of CeCl3, LaCl3, NdCl3, and PrCl3 are 11.5, 58.5, 14.4, and 5.4%, respectively. The particle size of resulting cerium concentrate was fairly uniform and about 0.1 mum.