Production of high-purity ThO2 from monazite ores for thorium fuel-based reactor

• Main Authors: Salehuddin, Ahmad Hayaton Jamely Mohd, Ismail, Aznan Fazli, Aziman, Eli Syafiqah, Mohamed, Nurul Aida, Teridi, Mohd Asri Mat, Idris, Wan Mohd Razi
• Format: Article
• Published: Elsevier 2021
• Subjects: Q Science (General); T Technology (General)
• Online Access: http://eprints.um.edu.my/28404/
• Institution: Universiti Malaya

The present study aims to investigate the optimum parameter in producing high-purity thorium dioxide (ThO2) using Di-2-ethylhexyl phosphoric acid (D(2)EHPA) and Aliquat-336 as solvent materials. The extraction and purification process was performed using l'h-RE](OH)(4) compound which was selectively precipitated from the monazite leach solution. Several parameters such as types of acid (HCl, HNO3 and H-2(SO4)), acid molarity (1M-6M), and solvent ratio (10%-30%) were investigated. The findings indicate that different solvents require a distinctive aqueous medium to extract thorium. The optimum concentrations of D 2 EHPA and Aliquat-336 in extracting thorium were identified to be at 1M H-2(SO4) and 4M HNO3 with 30% and 20% ratio, respectively. The multi-stage extraction process was successfully extracted and purified thorium at a purity of 96.8% (D(2)EHPA) and 98.0% (Aliquat-336). Subsequent conversion to ThO2 yielded a high-purity thorium dioxide at 99.1%. In general, the study elucidates that both solvents have the potential to be utilized as thorium extracting agents in preference to the conventional tri-butyl phosphate (TBP).