Hydrochloric acid leaching of an Elliot Lake uranium ore

CIM Bulletin, Vol. 73, No. 819, 1980

K.E. HAQUE and B.H. LUCAS, Research Scientists, G.M. RITCEY, Section Head, Extractive Metallurgy Section, Ore Processing Laboratory, CANMET, Energy, Mines and Resources Canada, Ottawa

Laboratory-scale hydrochloric acid leach tests were conducted on an Elliot Lake uranium ore. Hydrochloric acid leaches without an oxidant or with molecular oxygen (i.e., air or pure oxygen gas) as an oxidant favoured uranium and radium extractions. Conditions for maximum uranium, thorium and radium extractions with hydrochloric acid in the presence of sodium chlorate were determined. The highest extractions of uranium (96%), thorium (81%) and radium (91%) were obtained using a mixture of 44.0 kg HCl and 2.5 kg NaClO3 per tonne of ore at 75°C with 18 hours' retention. Flowsheets for two-stage leaching are proposed. The residues obtained from the second-stage leach contain uranium (0.002%), thorium (0.006%) and radium (15 to 20 pCi/g). Tailings of this nature are considered suitable for mine backfill, and, if pyrite is removed, suitable for surface disposal.
Keywords: Hydrometallurgy, Extractive metallurgy, Leaching, Hydrochloric acid leaching, Uranium extraction, Elliot Lake, Thorium extraction, Radium extraction, Ore processing, Environmental control.