Falconbridge Nickel Mines Limited

William Ronald Hatch

Ronald R Dunn

Sulphuric acid leaching has been used in the treatment of lateritic ores for the recovery of nickel and cobalt therefrom. However, in order to obtain good extraction from these ores, prolonged treatment using acid of high strength and also using high pressures and recycling steps have been necessary. In the improved method of the invention nickel and cobalt is solubilized from high-magnesia nickeliferous serpentine ores by leaching the ore with an aqueous solution of sulphuric acid while adding to the solution a reducing agent to maintain the redox potential of the solution at a value between 200 and 400 millivolts, measured against the saturated calomel electrode. This improved procedure increases the reactivity of the serpentine and results in maximum extraction of nickel consistent with minimum extraction of iron and magnesia and minimum acid consumption.

Acid leaching of nickel from serpentinic laterite ores

There is provided a cobalt ion exchange process for recovering cobalt from ammoniacal solutions comprising the steps of bringing the ammoniacal solution into contact with carbonaceous material, the redox potential of the solution being in the range +20 to -150 mV as measured by a platinum-calomel standard electrode pair, extracting the cobalt from the leach solution with a cationic ion exchange reagent, and recovering substantially all the cobalt from the ion exchange reagent by elution. The process of the invention enables cobalt to be removed from an ammoniacal leach solution which may also contain nickel and copper, in the form of a highly pure cobalt eluate.

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Bolton, Canada

William Ronald Hatch