Separation of thorium from a real acidic leach liquor solution by solvent extraction method with Di(2-ethylhexyl) phosphoric acid as extractant and chemical precipitation with ammonia

Due to the limited uranium reserves, the abundance of thorium compared to it, not being used in nuclear proliferation, and other advantages of thorium fuels over uranium fuels, the development of the thorium fuel cycle in various countries, including Iran, is considered. In this research, the separation and recovery processes of thorium from a real acidic leach liquor solution with a concentration of 500 mg/L thorium on a laboratory scale to produce thorium oxide precipitate were evaluated. The operating parameters affecting the extraction, stripping, and chemical precipitation processes of thorium include the type of extractant (acidic, basic, and neutral), the concentration of the extractant (0.05-1 M), aqueous phase acidity (0.032-6.92), equilibrium time (5-60 min), type and concentration of stripper (1-7 M) and precipitating agent were studied by the univariate method in each section. According to the experimental results, Di(2-ethylhexyl) phosphoric acid with a concentration of 1 M as extractant, aqueous phase acidity equal to 0.1, equilibrium time 60 min, sulfuric acid with a concentration of 5 M as a stripper, and ammonia as a precipitating agent were selected. Recovery of thorium from a real acidic leach liquor solution under obtained conditions resulted in the production of thorium oxide precipitate with a purity of 66%.