Investigation of Thorium, Cerium and Lanthanum Separation from Oxalate Concantrates.
Project no. 222 · Status: Kapanmış · 2016
Summary
Turkey has important quantities of thorium and rare earths reserves in Eskişehir-Beylikahır region. In this study, a synthetic nitrate solution was prepared keeping Th-REEs composition similar to that of the thorium-rare earth data of the oxalate intermediate product previously obtained from the ore. The separation effectiveness of solvent impregnated XAD resins for the separation of Th, Ce, La existing in nitrate solution and the separation of these ions with inverse phase extraction in a HPLC system utilizing a C-18 column were investigated. At the result of the experiments realized with TBP-XAD2 and TBP-XAD16 SIRs although the high extraction yields were obtained, the re-extraction yields were considerably low. It was attributed to the hydrophobic structure of the mentioned resins. For this reason, a new SIR was prepared with the impregnation of TBP to a XAD7 resin exhibiting hydrophilic property and the extraction and re-extraction studies were realized to obtain better yields. As the results of the experiments realized at the V/m: 25, pH:3, time:60 min. conditions; It was determined that Th was completely extracted in the newly prepared column, in contrary Ce and La existing in very high concentration (1500 mgL-1 and 750 mgL-1, respectively) in the feed solutions were extracted in negligible levels (10 mgL-1 and 6.0 mgL-1, respectively). The 65.24±2.00 % of thorium was re-extracted with 0.015M HNO3 elution solution at one step. In the inverse phase extraction experiments, using C-18 column and mobile phase as HIBA, the HPLC chromatograms taken in the existence of chelating agent Arsenazo (III) and 0.4 M HIBA, at pH=3 conditions, Ce, La and Th arsenazo complexes retention times were determined as 2,93, 2,92 and 6,97, respectively. In chromatograms taken from the solution mixture including Th, Ce and La, Ce and La peaks overlapping at the 2.93 min. retention time, while thorium arsenazo complex peak with 6.97 min. retention time differ other peaks and this shows that thorium is easily separated from La and Ce. Keywords: Thorium, Cerium, Lanthanum, Solid-Liquid Extraction.