Sandton-based chemicals reagent supplier and distributor Axis House believes mining in Africa is moving towards process optimisation through innovation to reduce costs and increase profits, explains Axis House group general manager Justine Stubbs.

“Mines are optimising various processes to achieve the most value and becoming more environmentally conscious by improving water disposal, recycling water and using non-hazardous products,” she highlights.

This is as a result of the water sources in Africa that often contain high levels of impurities which negatively affect the extraction process. “Recycling of water reduces the need for fresh clean process water,” Axis House product manager Muhammed Vawda explains.

“The use of treated and recycled wastewater provides a saving on pumping and storage costs – this also prevents the risk of affecting downstream users and is necessary for mines situated in areas with water scarcity,” he adds.

Stubbs points out that restrictive mining plans and policies in different regions, as well as orebodies that are not well defined present a challenge to investors. Further, slow mining output as a result of inadequate timeframes between mining and mineral processing means that the maximum extraction efficiency is reached too late.

“Managing cost per million tons is also critical to survival in the mining industry,” she emphasises, noting that Axis House’s quality extraction products reduce wastage and have a capture rate which optimises yield-to-cost ratios.

Moving Forward

Axis House therefore focuses on creating reagents that selectively float specific minerals in the processing plants, rather than the collective minerals present in the feed, to improve optimisation and efficiencies, explains Stubbs. “As the feed composition changes, the processing conditions can be changed to accommodate [the feed] accordingly,” she adds.

Vawda believes that mines should apply new chemistry, such as replacing the current, hazardous reagents with better performing, non-hazardous reagents to gain more from mineral processing. “Axis House has biodegradable and non-hazardous reagents that are more environmentally friendly than the current technology used,” he highlights.

However, Vawda points out that, currently, biodegradable reagents are not the main focus of African mines; rather, mines focus on the performance of the chemicals and their hazardous nature to minimise transport and storage risks.

An example of Axis House’s biodegradable products is Rinkalore 10 – an oleochemical industrially derived from plant fats and oils. It has been purposefully designed to complement copper and/or cobalt oxide flotation circuits. It is a base metal oxide collector that targets slower moving copper, and is effective on hard-to-float copper and cobalt ores.

Axis House also has a range of frothers that are non- hazardous performance products which have a high flash point. The main advantage comes from the selectivity displayed by these custom-built frothers through a series of on-site tests carried out by their team of process engineers.

With significant potential growth that lies in sustainable and renewable energy within the mining industry, Axis House also focuses on the micro scale of production to support the trend of streamlining plants and increasing outputs, by creating products that are “ready-to-use” in the mineral processing and do not require additional ingredients or to be diluted.

Advantages of using these products mean that less energy is used, as the mixing plants are eliminated, Vawda puts forward. “We are also looking at improving solid-liquid separation processes, which translates to less moisture fed to the dryers in [mineral] processing, and less contaminants recycled to the flotation process,” Vawda adds. He explains that the flocculent Brontë range of products conducts this well.

The flocculent Brontë range constitutes polyacrylamides and polymers that aggregate particles to form larger particles that settle faster as they are heavier, explains Vawda. Clean water is drained from the top of the thickener once all the particles have settled, and can be reused by the mine.

As the flocculent Brontë range is a key component in recovering water from waste streams and separation processes, there is a high demand for this product range in Africa, he adds. “The flocculent Brontë range removes clean water from concentrate and tailing streams in a more cost effective and faster manner than drying the streams naturally,” Vawda highlights.

Improving solid-liquid separation processes will improve the flotation behaviour, while reducing the overall production cost per ton of ore, Stubbs concludes.