URANIUM RECOVERY FROM SULPHATE LEACH SOLUTION CONTAINING CHLORIDE USING A MIXED SYSTEM OF D2EHPA AND CYPHOS IL-101

摘要

Uranium recovery from its sulphate leach solution containing high chloride concentration is a great challenge because traditional solvent extraction using tertiary amine suffers from low uranium extraction efficiency. A new solvent system consisting of D2EHPA and Cyphos IL-101 was studied to solve this problem.The organic system consisting of D2EHPA and Cyphos IL-101 formed an internal compound with two molar D2EHPA and one molar Cyphos IL-101. The mixed organic system performed well in uranium extraction and its separation from Fe(lll) in sulphate solutions. The mixed organic system demonstrated high tolerance to chloride up to 12 g/L in terms of uranium extraction and its separation from iron. More than 83% U was extracted with the organic system consisting of 0.05 M D2EHPA and 0.05 M Cyphos IL-101 in Shellsol D70 while less than 10% Fe(lll) was extracted within the pH range of 0.5-1.25, resulting in high separation factor of U over iron. Almost all co-extracted iron could be scrubbed using 0.5 M sulphuric acid. The co-extraction of vanadium was significant, but less at low pH of <0.5. The extraction of other metals including Al, Cu, Mn, Mg and Ca was insignificant, resulting in ready separation of uranium from them. Effective uranium stripping was achieved with 4 M H_2SO_4 or higher using multiple stages. The kinetics of uranium extraction and stripping was fast and good phase separation was observed.