xygen-based control technology with the potential to increases gold mine profitability, reduce cyanide consumption and increase gold recovery in refractory ores.

Unlocking hidden reserves

Most gold occurs in tiny particles locked within rocks. These gold concentrations are so low that it typically takes about one ton of ore – usually brown, iron-stained rock – to yield just a few grams of gold.

Once this ore has been excavated from the mine, it is crushed to create small particles. The next step entails leaching the ore particles to recover the gold. Water and cyanide are typically added to the ore at this stage to transfer the gold from the solid phase to a water-based gold-cyanide complex. Oxygen is needed for the formation of this complex. However, side-reactions of the cyanide can occur in refractory ores, compromising process efficiency. In addition, cyanide is an expensive and hazardous chemical and its use is restricted or illegal in many parts of the world.

Adding value to the recovery process with GOLDOX®

GIGC has developed an innovative dissolved gas management solution to reduce the overall requirement for cyanide and increase the gold leach rate by raising dissolved oxygen levels. GOLDOX® not also oxidizes the gold itself (to create a water-soluble complex), it also oxidizes and deactivates other compounds, such as iron and copper salts, which would otherwise also compete with the available cyanide. It thus reduces the cyanide cost substantially, while simultaneously reducing the waste cyanide load to be destroyed. In some cases, GOLDOX raises the percent of gold recovered by reducing the volume of cyanide lost to side reactions. This, in turn, increases the rate of complex formation between gold and cyanide.

Leaching and beyond

Looking beyond the pre-oxidation and leaching steps, oxygen can optimize productivity and reduce costs by fine-tuning many other steps such as ore roasting, high-pressure pre-oxidation, atmospheric pressure pre-oxidation, cyanide destruction and waste(water) treatment. In some cases, carbon dioxide can be used to enhance dissolved gas floatation upstream of the hydrometallurgy (hydromet) process.