• Analytical Science and Technology
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• v.8 no.4
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• pp.553-559
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• 1995

An extraction chromatographic method of separating rare earth impurities from high purity $Nd_2O_3$, $Sm_2O_3$, $Gd_2O_3$, $Er_2O_3$, $Dy_2O_3$ and $Yb_2O_3$ was studied by using $HCl-NH_4Cl$ as moving phase and P507 as stationary phase. After the impurities were enriched from the eluate by chelant-activated carbon, the active carbon was ashed and the ignited residue was used to prepare the sample electrode for spark source mass spectrometric determination. The impurities in 99.9999% rare earth oxide can be determined by the proposed method with recovery over 80%.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.2926-2936
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• 2021

Rare-earth (RE) industries generate a massive amount of radioactive residue containing high thorium concentrations. Due to the fact that thorium is considered a non-economic element, large volume of these RE processed residues are commonly disposed of without treatment. It is essential to study an appropriate treatment that could reduce the volume of waste for final disposition. To this end, this research investigates the applicability of carbon-based adsorbent in separating thorium from aqueous phase sulphate is obtained from the cracking and leaching process of solid rare-earth by-product residue. Adsorption of thorium from the aqueous phase sulphate by carbon-based electrodes was investigated through electrosorption experiments conducted at a duration of 180 minutes with a positive potential variable range of +0.2V to +0.6V (vs. Ag/AgCl). Through this research, the specific capacity obtained was equivalent to 1.0 to 5.14 mg-Th/g-Carbon. Furthermore, electrosorption of thorium ions from aqueous phase sulphate is found to be most favorable at a higher positive potential of +0.6V (vs. Ag/AgCl). This study's findings elucidate the removal of thorium from the rare-earth residue by carbon-based electrodes and simultaneously its potential to reduce disposal waste of untreated residue.

• Nuclear Engineering and Technology
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• v.56 no.11
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• pp.4611-4619
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• 2024

This study focuses on the development of a curated separation system aimed at separating thorium ions as part of a recovery plan for managing the thorium radionuclide in the rare earth element (REE) processing industry. As a step towards advancing technology readiness, the separation system employs the electrosorption technique, which involves the migration and storage of thorium ions in the electrical double layers on the porous surface of a carbon-based electrode. Using a prototype electrosorption cell operated at an applied voltage of 1.0 V, the system successfully achieved a thorium ion recovery rate of 84.5 ± 0.29 %, with an impressive electrosorption capacity of 105.26 mg-Th/1 g-carbon. Notably, despite the presence of higher concentrations of REE as competing ions, greater selectivity towards thorium was observed which likely attributable to its larger ionic radius, higher electron affinity, and greater distribution coefficient. These findings highlight the efficacy of the curated separation system and its potential to balance between REE economic significance as well as a protection to the environment.