Comparison of oxidants for the leaching of uranium ores in sulphuric acid

CIM Bulletin, Vol. 75, No. 841, 1982

K.E. HAQUE and G.M. RITCEY, Extractive Metallurgy Laboratory, Mineral Sciences Laboratories, CANMET, Energy, Mines and Resources Canada, Ottawa

Laboratory-scale sulphuric acid leach tests were conducted on Elliot Lake and Rabbit Lake ores in the presence of various oxidants, namely: Fe2(SO4)3, Cl2, H2O2, NaClO3, MnO2, H2SO5, HNO3, Oxone, K2Cr2O7, KMnO4, O3 and O2. Uranium extraction is significantly accelerated when an oxidant is present in the leach slurry. Uranium extraction of 96-99% can be achieved by maintaining the oxidation potential of the leach slurry in the range of 400 to 500 mV (S.H.E.). A rough cost comparison of all the oxidants indicates that the use of Fe2(SO4)3, O2, O3, Cl2, HNO3 or MnO2 is far less expensive than NaClO3 and the uranium extraction rates are similar to or better than with NaClO3. For uranium extraction, it is concluded that gaseous oxygen (i.e., air or oxygen) would be the most effective and economical oxidant for the 24- to 36-hour leach of Elliot Lake ore; whereas for the 8- to 12-hour leach of Rabbit Lake ore, a strong chemical oxidant (e.g. NaClO3, H2O2, O3, K2Cr207, H2SO5 or HNO3 would be a logical choice.
Keywords: Hydrometallurgy, Oxidants, Leaching, Uranium ores, Sulphuric acid, Elliot Lake, Rabbit Lake, Acid leaching.