Several gold mines across sub-Saharan Africa are saving up to 70% in costs by switching from delivered oxygen to their own on-site systems, reports oxygen and nitrogen supplier O2Africa commercial director David Kempe.

The company’s pressure swing adsorption (PSA) technology is capable of producing high-purity oxygen at a mine site, reducing reliance on external suppliers and deliveries, consequently strengthening gold recovery in the process.

The company’s PSA system can separate oxygen from air using zeolite. This “guarantees a steady, cost-effective and reliable stream of oxygen” for gold extraction, especially for mines in remote areas, where oxygen delivery can be delayed or unreliable, he explains.

The main application of the technology is during the gold leaching process, where oxygen is fed into carbon-in-leach or carbon-in-pulp tanks, thereby helping to increase gold recovery by improving leaching kinetics, lowering retention time and reducing cyanide consumption while also strengthening profits.

“Maintaining a consistent flow of oxygen is a key factor in optimising gold extraction. O2Africa’s technology directly controls flow rate and purity, yielding faster leaching, greater recovery and less reliance on toxic chemicals,” Kempe explains.

The company’s systems can also be used in related applications, including wastewater treatment and oxygen-enriched combustion for smelting or refining gold.

He adds that mining operators appreciate the greater control over production processes without the complications stemming from delivery delays or disrupted supplier schedules.

“This really lets mines take control of their own process [while cutting] their operational costs,” says Kempe.

Installing a PSA generator at a mine brings significant environmental benefits, he says, adding that the need for delivery trucks is eliminated, thereby reducing emissions and lowering a mine’s carbon footprint.

Enhanced process control further translates into less cyanide being used and less toxic waste being produced, adding to the technology’s green credentials, says Kempe.

Easy Integration

O2Africa’s containerised systems can be deployed on site, with minimum site preparation, reducing their physical impact on operations.

“We’re helping mines become more environmentally responsible without adding additional operational complexities.”

Generating oxygen on site “resonates strongly” with growing pressures on many mining operations for responsible sourcing and sustainable operations, adds Kempe.

Also, the company’s equipment is designed and manufactured in South Africa, employing local skills and adding value to South Africa’s industrial transformation.

“This is a South Africa-specific solution designed for South Africa’s mines and for Africa’s mines in general, employing local expertise and boosting employment,” notes Kempe.

In terms of hurdles faced by some African mining operations, he says resistance to change and a lack of understanding about the benefits of an on-site oxygen plant “were high on the list”.

O2Africa overcomes these barriers by training operational teams to manage their own systems, employing redundancy measures and bolstering robustness to account for power fluctuations, and offering ongoing technical support from its team of engineers.

“Training is a big part of making sure the mines get the most from their investment and become less dependent on external suppliers of oxygen.”

Kempe adds that the adoption of on-site oxygen plants is growing, as mines appreciate the operational and financial benefits provided by such a solution, with gold operations in South Africa, Ghana and Guinea consulting O2Africa on PSA systems.

Some mines are choosing to combine on-site oxygen generation plants with delivery to account for peak-demand periods, adding greater flexibility and reducing reliance on a single supplier.

“This lets mines be much more adaptable and resilient under changing conditions, without putting their production at risk,” says Kempe.

O2Africa is developing smart monitoring systems for its PSA technology to enable mines to track performance in real time, predict maintenance needs and avoid unanticipated shutdowns.

From its operations base in South Africa, the company maintains a convenient inventory of spare parts, which also helps to reduce delivery lead times and operational bottlenecks.

“We want to enable mines to produce gold more efficiently, with less waste, while strengthening their financial performance and delivering a greater return for stakeholders and their communities,” he concludes.