Pressure Oxidation Process

Metso can provide a complete pressure oxidation plant including all auxiliary processes for refractory gold sulfide oxidation. Gold is efficiently released from the sulfide matrix for the subsequent leaching process, whether cyanidation or chloride leaching.

The Metso pressure oxidation main process steps:

• Carbonate and chloride removal    
• Pressure oxidation    
• Gas scrubbing    
• Conditioning (hot curing)    
• Solid-liquid separation    
• Arsenic removal and neutralization

Metso’s solutions consist of complete functional units integrated into the processing plant. The key equipment of the pressure oxidation process is the autoclave, equipped with Metso’s mixing technology, to enable efficient use of oxygen. All main and auxiliary equipment, from the autoclave feed to flash tanks, is included in the autoclave train package.

In refractory gold processing, efficient carbonate removal, conditioning, and neutralization steps are handled with the modular Metso OKTOP® reactor packages combining process, automation, and equipment know-how. If chloride enters the autoclave, it is efficiently washed out in the Metso Larox® filtration plant with minimum water consumption.

Metso thickeners for counter-current decantation provide a robust and low-cost solution for the oxidized slurry. The toughest environmental regulations are met with Metso’s vent gas technology, and harmful components captured from all autoclave exhaust gases.

Proprietary equipment for Metso's pressure oxidation process includes:

• Metso OKTOP® Autoclaves    
• Metso Atmospheric OKTOP® reactors with mixing technology    
• Thickeners and Metso Larox filters    
• Gas scrubbers
• Flash tanks    
• Automation and process control systems