Her Majesty the Queen in Right of Canada, as Represented by the Minister

Canadian Patents & Development Ltd.

Kazi E Haque

Gordon M Ritcey

Bernard H Lucas

James M Skeaff

Peter D Kondos

Daniel Laforest

Wesley F Griffith

Joe Iuliano

John C MacDonald

A process is disclosed for the direct recovery of gold from cyanide leach liquor, thiourea leach liquor or Bio-D leach liquor. The process comprises reduction precipitation of the gold from solution by the addition of stabilized alkali metal borohydride, preferably sodium, potassium, lithium or ammonium borohydride, at ambient temperature and pressure. High purity gold is obtained by heating the reduced precipitate to about 1200.degree. C. The barren solution is in a condition such that it can be recycled to the upstream process.

Recovery of dissolved gold by sodium borohydride (NaBH.sub.4) reduction

A method of eliminating the foam above a slurry of a corrosive liquid and solid matter where the foam is caused by a gas evolved by the reaction between the heated corrosive liquid and the solid matter comprising providing the heating energy by microwaves. This method has been found to be particularly useful in the sulphuric acid leaching of an ore concentrate in the production of beryllium hydroxide.

Use of microwave radiation to eliminate foam in ore leaching

Uranium ores, concentrates, calcines or tailings are processed to remove radium and thorium as well as uranium. Selected ores, concentrates or tailings, or if more appropriate, chlorination calcines thereof, are leached by selected aqueous chlorine-containing media (preferably in two stages) until uranium, radium and thorium are substantially all dissolved, with the insoluble residual solids being suitable for disposal. The leach solution is treated to recover sequentially uranium, usually thorium, and radium by selected techniques. The radium recovered can be disposed of in any environmentally-acceptable manner. The amount of iron in the residual leach liquor should be controlled to avoid iron build-up, with the barren leach solution being suitable for recycle.

Uranium ore processing

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Ottawa, Canada

Kazi E Haque