Placer Dome Technical Services Limited

Barrick Gold Corporation

Eldorado Gold Corporation

Jinxing Ji

Paul George West-Sells

Ralph Peter Hackl

Christopher Andrew Fleming

James A King

Cesare Giosue Ferron

Roman Berezowsky

Paul Skayman

A process for reducing arsenic content from arsenic-bearing gold concentrate or other arsenic-bearing gold materials to produce a low arsenic-bearing gold concentrate. The process may comprise adding oxygen, water, and/or acid to an acidulated arsenic-bearing gold concentrate slurry and reacting them together in an autoclave at an elevated pressure and temperature in a pressure oxidation step. In one or more examples, the process may further comprise processing the oxidized concentrate slurry in an arsenic re-dissolution step to dissolve unstable solid arsenic compounds, and applying a first solid/liquid separation and wash step to form a first washed slurry/solid and first acid-containing solutions. The process may further comprise reacting the first washed slurry/solid with sulfur dioxide in a reductive leach step, and applying a second solid/liquid separation and wash step to form a second washed slurry/solid and second acid-containing solutions. The second washed slurry/solid may be a low arsenic-bearing gold concentrate.

Method for reducing arsenic content in arsenic-bearing gold material

Processes are provided for recovering precious metals from refractory materials using thiosulfate lixiviants. The processes can employ lixiviants that include at most only small amounts of copper and/or ammonia and operate at a relatively low pH, reduction of polythionates, inert atmospheres to control polythionate production, and electrolytic solutions which provide relatively high rates of precious metal recovery.

Method for thiosulfate leaching of precious metal-containing materials

Processes are provided for recovering precious metals from refractory materials using thiosulfate lixiviants. The processes can employ heap leaching or lixiviants that include one or more blinding agents.

The present invention is directed to a multi-compartment autoclave using inter-compartment dividers having one or more underflow openings for passing a feed stream between compartments.

Autoclave with underflow dividers

The present invention is directed to a precious metal recovery process in which basic ferric sulphates and/or jarosites are controlled by a number of mechanisms, including control of the oxidation reaction conditions in the first autoclave compartment, hot curing of the autoclave discharge slurry, and/or contacting of the autoclave feed slurry with the hot cured discharge liquid.

Reduction of lime consumption when treating refractory gold ores or concentrates

Reduction of lime consumption when treating refractor gold ores or concentrates

The autoclave of the present invention includes an impeller having a conduit to recirculate or introduce a molecular oxygen-containing gas into the slurry. The outlets for the gas can be located in the blades of the impeller for thorough dispersion of the gas bubbles in the slurry. A sparge tube for introducing an additional molecular oxygen-containing gas into the slurry can be used in conjunction with the impeller to provide a high molecular oxygen transfer rate to the slurry.

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Burnaby, Canada

Jinxing Ji