SOLVENT EXTRACTION OF THORIUM FROM RARE EARTH ELEMENTS IN MONAZITE THORIUM CONCENTRATE

Solvent extraction is a powerful separation technique in the preparation of nuclear grade thorium.In this study, monazite thorium concentrates produced from Malaysian monazite were used.Thorium was extracted from an aqueous nitric acid medium with TBP (30%) in kerosene and Aliquat-336 (10%) in kerosene, respectively.Constant experimental conditions were used for the extraction in terms of the molarity of nitric acid, concentration of extractants in kerosene, organic/aqueous volumetric ratio, mixing time, and contact time between phases.The stripping process was carried out with distilled water.The determination of thorium and rare earth elements (REEs) in the monazite thorium concentrates and aqueous solutions were performed by using inductively coupled plasma mass spectrometry (ICP-MS).The concentrations of thorium in the thorium concentrate samples were in the range of 11.58 -83.56%.Three stages of extraction and three stages of stripping were carried out for the extraction of thorium from the REEs in the nitrate solution.The results of the study showed that the thorium extraction efficiency was in the range of 60.96 -99.75% using TBP (30%) in kerosene and Aliquat-336 (10%) in kerosene.Thorium was stripped from the loaded TBP (30%) in kerosene and Aliquat-336 (10%) in kerosene at an average stripping percentage of 89.04% and 75.75%, respectively.The stripped aqueous solutions were analysed, and it was shown that the thorium content was in the range of 29.49 -91.28%.This study indicated that both extractants can be successfully used to recover thorium from REEs, but in order to increase the purification of thorium, the extraction and stripping process cycle should be increased.