A new copper pressure oxidation (Cu POX) leaching process aims to address the changing needs of the copper extraction industry, faced by the ongoing depletion of deposits and increasing environmental and efficiency demands.

The Metso Cu POX process is a hydrometallurgical method for the treatment of copper sulfide concentrates at lower capacities which aims to maximise copper recovery while also reducing environmental impact. The company’s proprietary OKTOP autoclave unit is used to oxidise copper concentrate under high pressure and temperature, resulting in a copper-bearing pregnant leach solution (PLS) to be further treated in solvent extraction and electrowinning (SX-EW) processes, where copper is recovered as high-purity London Metal Exchange, or LME, grade A cathodes.

“Copper sulfide minerals require specialised leaching conditions to achieve high recovery rates. Metso’s Cu POX leaching utilises high-temperature oxidation to convert sulphide sulphur into sulphate and sulphuric acid, ensuring efficient copper dissolution. This technology offers a high-performance solution with high, up to 99%, copper recovery rates, ensuring maximum extraction of valuable metals from the ore. The process also minimizes environmental impact by reducing emissions and optimizing the use of resources through, for example, closed loop process steps reducing the use of water,” says Metso technology manager: copper hydrometallurgy Petteri Pesonen.

The flexible and scalable Cu POX process accommodates various capacities and raw material compositions. The pre-designed process and equipment package is designed to enable fast ramp-up to production and integrates with SX-EW infrastructure. The Cu POX plant can also be implemented to improve existing heap leaching SX-EW operations to complete depleting heap leaching PLS production.

Metso notes that it can provide full support from batch tests, modelling and pilot tests to engineering, equipment deliveries and plant commissioning, and training. In addition, it provides services, spare parts and digital solutions to help optimise continuous process and plant performance.