STUDY OF SEPARATION OF THORIUM FROM IRON AND RARE EARTH METALS IN NITRIC ACID SOLUTION BY SOLVENT EXTRACTION USING TRIOCTYLPHOSPHINE OXIDE

• Main Author: (NIM : 12513042), BRILIANT
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/26156
• Institution: Institut Teknologi Bandung

Thorium is a metal that has radioactivity and potentially used as an alternative nuclear fuel to substitute uranium. Nuclear fuels are commonly used for electrical power plant and the development of this kind of power plant is very important especially for Indonesia. According to data from BATAN 2017, Indonesia is reported to have 130.974 tons of thorium reserves. In order to be suitable for nuclear fuel, thorium must be purified and separated from it’s impurities such as iron and rare earth element (REE). Processing route that has been effectively proven to extract thorium and separate it from the impurities is hydrometallurgical process through leaching followed by separataion of thorium from co-dissolved metals with certain methods. In this research, separation of thorium from iron and REE by solvent extraction using Trioctylphosphine Oxide (TOPO) is studied. Preparation of solution samples for the solvent extraction tests was started with acid digestion of thorium ore from Mamuju, West Sulawesi using 95% H2SO4 at 160oC for 60 minute. Gray mud produced from the acid digestion was then dissolved in water to separate silica and other gangue minerals that were not soluble in water with Th, Fe and LTJ-sulphate which were dissolved in water. Filtrate obtained from solid-liquid separation was neutralized by solution of ammonium hydroxide 25% until the solution pH reached 4.5. Precipitate from the precipitation process then re-dissolved in nitric acid solution for used in solvent extraction experiments. A series of solvent extraction experiments was carried out under variations of nitric acid concentration, extraction time, concentration of extractant in diluent (g/mL) and the ratio of organic solution volume to aqueous solution volume (O/A). Stripping experiments of loaded organic was conducted under variation of nitric acid concentration as stripping agent. <br /> <br /> <br /> The experimental results show that the best condition for thorium extraction was obtained at 3M nitric acid, 10 minutes extraction time, extractant concentration of 0.05 g/mL and O/A ratio 1 : 1 which resulted in Th extraction of 97.26%. At this condition, co-extracted Fe and REE were 7.97% and 62.15 %, with separation factor of &#946;Th-Fe and &#946;Th-LTJ were 273.62 and 14.43, respectively. Based on the constructed McCabe-Thiele diagram, 2 stage of extraction is needed to acquire thorium extraction level of &#61619;99% at nitric acid concentration of 3M, 10 minutes extraction time, 0,05 g/mL TOPO concentration and O/A ratio 1:1. For the stripping experiment, the highest stripped Th was 51.37% with co-stripped Fe and REE of 2.72% and 2.55%, respectively, which was obtained at nitric acid concentration of 0.3M. <br />