Hydrochem Developments Ltd.

Kenneth J Fair

John C Schneider

Gezinus Van Weert

A process for recovering gold from a refractory sulfidic ore which has been suspended in an aqueous slurry and oxidized using nitric acid so that substantially all of the gold in the ore is made available for recovery and at least a portion of the sulfidic components present during the oxidation are oxidized to elemental sulfur, comprises bubbling air as a discontinuous phase upwardly through the oxidized slurry, thereby creating a froth containing elemental gold and sulfur. The froth is separated from the slurry to provide a concentrate, and the gold is recovered from the concentrate.

Process for recovering gold from refractory sulfidic ores

An oxidation process for releasing a metal of interest in an ore is described. The process is especially useful for releasing a metal of interest entrapped in a refractory ore. The process comprises reacting the ore with nitric acid until sufficient oxidation has occurred to release the metal of interest so that it may be recovered by conventional techniques. Nitric acid is regenerated in situ by aerating the liquid medium and contacting it with the off gases generated by the oxidation. The process is continuous and the nitric acid is recycled to the reactor preferably after removal of accumulated sulfate.

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Willowdale, Canada

Kenneth J Fair