Effectiveness study of thorium extraction from hydrochloric acid using di (2-Ethylhexyl) phosphoric acid (D 2 EHPA)

Abstract

Thorium extraction from thorium tetrachloride aqueous solution (ThCl4) was performed by using organic solution of Di-(2-ethylhexyl) phosphoric acid in kerosene (D 2 EHPA/K). The study aims to determine the organic concentration parameter in the solvent and the mixing time that influences the extraction efficiency. Mix thorium-rare earth hydroxide (Th-RE)(OH)4 from local monazite concentrates was dissolved in 3 M and 4 M of hydrochloric acid, respectively. The aqueous solution of (Th-RE)(OH)4 was mixed with the organic solvent D 2 EHPA/K at different concentrations of 10%, 20%, and 30%, respectively. The mixture was stirred for 5 to 20 min before the aqueous and organic phase were separated. Thorium concentrations before and after extraction were analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The result indicates that thorium concentrate in aqueous solution (Th-RE)OH4 is in a range of 119.40 ± 3.43-121.13 ± 3.18 ppm. The highest extraction efficiency for thorium was 99.8%, extracted using D 2 EHPA/K at 30% of concentration. The result indicated that the optimum mixing and separation times of thorium from aqueous solution into organic phase was 5 min, respectively. Therefore, this research proves that D 2 EHPA is potentially be used as thorium extraction agent digested in hydrochloric acid.