Extraction and back-extraction behaviors of 14 rare earth elements from sulfuric acid medium by TODGA

The unique physical and chemical properties of rare earth elements lay the foundation for their extensive application. N,N,N',N' Tetra-octyl-3-oxopentanediamide (TODGA) is excellent in its ability of extracting rare earth elements and it is favored for green initiative. In this paper, the extraction and back-extraction of 14 rare earth elements by TODGA were studied. Experiments show that in conditions of 6 mol/L sulfuric acid, the extraction temperature of 25 degrees C, the phase ratio of 1:1 and 0.04 mol/LTODGA (aviation kerosene as the diluent), the extraction rates of 14 rare earth elements including lanthanum, cerium, praseodymium, neodymium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium were 99.00%-99.73%. Mixed with hydrochloric acid and nitric acid (HCl 3.5 mol/L, HNO3 0.5 mol/L), the recoveries of the 14 rare earth elements are 91.52%-99.91% when the extraction temperature is 25 degrees C and the ratio is 1:1. The following application is based on the optimum conditions above with practical samples (from the roasting production line of China North Rare Earth High-tech Company Limited) for extraction and back-extraction experiments. Experiments show that TODGA has excellent enrichment effect on 14 rare earth elements, the extraction rates are 91.36%-99.80%, the back-extraction rates are 87.29%-99.64% and the total recoveries are 81.19%-99.44%. (C) 2018 Published by Elsevier B.V.