Afrox has developed a unique and fully integrated end-to-end product service offering for the global gold mining industry to optimise metallurgical gold leach using oxygen. Rob de Zoeten, metallurgist at Afrox, says that understanding oxygen demand is absolutely critical to ensuring successful metallurgical gold leach optimisation.

Afrox Goldox“However, the importance of accurately establishing total oxygen requirement is often overlooked and, unfortunately, in many cases undersized on-site oxygen plants are installed. These cannot produce sufficient oxygen to optimise the leach,” he adds.

Afrox’s Goldox process performs a dual function. Through the introduction of pure oxygen in the preconditioning stage to the ore slurry, the dissolved oxygen concentration is increased, reducing the ore reactivity. This results in an increased gold leaching rate, which improves gold recovery and profitability.

The Goldox offering provides an oxygen demand test programme for specifying the oxygen demand requirements and the supply of oxygen using parent company Linde Engineering’s proprietary state-of-the-art onsite Vacuum Pressure Swing Adsorption (VPSA) technology. VPSA is an ambient temperature technology which takes advantage of the different binding capabilities of various gas molecules to a solid, porous material such as zeolites. The VPSA process cycles between adsorption and desorption of impurities as the feed gas flows through adsorber vessels in order to produce a continuous high purity product gas. Since heating or cooling is not required, cycle time can be short, usually less than a minute, which results in a long lifetime for the adsorbent material.

According to de Zoeten, VPSA has demonstrated excellent results in a variety of commercial applications in the mining, chemical and refining industries. “For low purity (<95%) applications with flow rates from 10 - 342 tpd, which are the typical requirements for gold mining applications, VPSA has proven to be the most cost-effective solution. The VPSA plants have a very low specific energy consumption, and operate at low pressure, with booster compressors to achieve customer pressure demands. They offer an extremely competitive capital and operating cost per tonne of oxygen produced.”

VPSA plants provide oxygen on demand with easy turndown from 0 - 100%, have high availability, are fully automatic, and can be remote controlled and monitored. VPSA plants are standardised through modular construction, enabling reduced field construction and commissioning time.

The Goldox offering also includes the supply, installation and commission of the oxygen reticulation network, flow control panels with safety interlocks and the oxygen injection system. Afrox can provide on-going maintenance and downstream oxygen control management if required.

As part of the Goldox product offering, Afrox provides a downstream oxygen management service through which Afrox operates and maintains the oxygen injection equipment to achieve the desired dissolved oxygen (DO) levels in the leach as required, freeing up the plant metallurgists to concentrate on managing the gold plant. Afrox will also, through Linde Engineering, manufacture, supply, deliver, install and commission plants throughout Africa and will operate and maintain these plants to supply oxygen to its customers.

Image credit:Copyright: kesu87 / 123RF Stock Photo


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