Process for the separation of thorium and rare earth elements from radioactive waste residues using Cyanex (R) 572 as a new extractant

摘要

In this paper, a process for the separation of thorium (Th) and rare earth elements (REEs) from radioactive waste residues of ion-absorbed type rare earth minerals using Cyanex (R) 572 (C572) as a new extractant has been developed. The extraction and stripping properties of Th and REEs with Cyanex (R) 572 were studied systematically. The separation factor of Th to Lu, beta(Th/Lu), are higher than 80 and 1.46 x 10(3), when the equilibrium HCl concentration is larger than 03 and 1.0 mol/L, respectively. The separation selectivity of Th and REEs showed good performance in the extraction system consisting of C572 and isooctanol in 260# kerosene with the beta(Th/Sigma REEs), value of 438 x 10(4). The leaching rates of Th and REEs from the roasted waste residues by HCl were found to be 69.6% and 92.1%, respectively. Recovery of Th and REEs can be achieved by total 10 stages of extraction, scrubbing and stripping section. (C) 2017 Elsevier B.V. All rights reserved.