Afrox is assisting in gold extraction with the reliable supply of specialty gases to an industry that relies on having a high purity across a broad range of mining activities.

The specialty gases are required in a variety of sectors – including metallurgical processing, purification and refining of ore into gold bars.

Afrox is one of the leading suppliers of these gases into the local gold mining industry, providing instrument grade gases or gas mixtures for specific analytical requirements and can be made to order if required.

A key application of these custom-developed mixtures is checking the calibration of the sophisticated analytical instruments that monitor the quality of air breathed by personnel.

Specialty gases also operate and calibrate the underground gas detection sensors that continuously “sniff” for naturally occurring toxic and flammable gases such as methane and carbon monoxide, both of which are odourless and therefore undetectable by humans. 

The gas mixtures required to test and calibrate underground sensors located in key positions are transported in steel cylinders, rather than the traditional aluminium cylinders, which reduce the risk of sparking in this hazardous environment and are more cost efficient.

Afrox’s HiQ® 60 range of specialty gas products offers the mining industry flat-line stability for 60 months from date of manufacture.  The HiQ® 60 range has a longer shelf life than conventional products, so there is no need to recalibrate, and every mixture is certified to be pure.

Still in the all-important arena of safety, Afrox is a leader in the design of Self-Contained Self-Rescuers which enable mine personnel to breathe while escaping to a safe area, or return to the surface in the event of an unsafe underground atmosphere. Thelatest version of its award-winning design, the Afroxpac35i, is a closed-circuit, self-contained oxygen breathing apparatus that makes use of an efficient bi-directional re-breathing system in which exhaled gas makes two passes through the carbon dioxide removal/oxygen generation canister before the oxygen-rich gas returns to the user.

Metallurgy

A diversity of speciality gases also play a pivotal role in the laboratories servicing gold mining operations. Instrument grade pure gases such as synthetic air, helium, hydrogen or nitrogen are used to zero and purge analytical equipment. High purity gases are also used, for example, in inductively coupled plasma (ICP) analysis and atomic absorption spectroscopy measurements (AAS). Specialty gas equipment is used in many areas to control gas cylinder pressures, while ensuring purity is not compromised. ICP mass spectroscopy is typically used to determine the purity of the refined metals being produced by the mine. Techniques like this require high purity specialty gases with very low levels of impurities, such as ICP grade argon.

Environmental measurements for air, water and ground pollution in and around a mine use a number of individual calibration standards to measure nitric oxides, VOC and BTEX emissions. The requirement here is for low level reactive calibration with flat line stability, as well as other environmental mixtures produced to meet the requirements of regulatory agencies around the world.

Gold extraction

Several years ago Afrox innovated a new leach feed diagnostics system developed for in the field evaluation of oxygen demand characteristics. Goldox™ is a process developed for the use of oxygen in cyanide gold leaching. First introduced to South African gold mines in the mid-1980s, it is now used by mines in North America, Australia and South America, establishing it as an internationally-proven technology. Benefits include capital savings on new plant, optimised cyanide usage and potentially lower and stable residue grades. The technology can also be retrofitted unobtrusively to existing plants.

The 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, resulting in an increased gold leaching rate which improves gold recovery and profitability.

End to end solution

Afrox differentiates itself in the mining market by offering customers an end-to-end solution that is fully integrated.  Value is added to these processes, both from a financial and a productivity perspective, by sourcing the necessary consumables, equipment and gases, as well as on site customer-specific support and training, from a single supplier. Welding consumables for fabrication in the mining environment range from industry-leading general purpose and low hydrogen electrodes, to the more exotic nickel and chrome alloys for welding high corrosion resistant materials and duplex stainless steels.

This 360 degree solution is being recognised and exploited by the market, whether in combination as a fully-integrated bundle to complement clients’ processes, or provided on a menu-type basis.

Afrox’s quality range of gas equipment extensively utilised within the gold mining industry conforms to all relevant national and international safety standards. To further support the gas equipment products, the company offers dedicated training for the safe use of gases and gas equipment.