Gauteng East Rand-based, privately owned mining house Upward Spiral 1471 has introduced new belt filter technology at its ERPM operation, in Benoni, with the aim to lower operational costs, improve efficiency and deliver environmental benefits.

The filtration system is designed for mineral processing applications and eliminates the need to pump contaminated water from its mining operations to tailings dams off site, the company says in a statement.

While the technology itself is not new, applying it in gold processing is “innovative”, Upward Spiral asserts.

“Traditionally, filtration of mineral slurries happens on a laboratory scale. On a large industrial scale, however, gold plants typically don’t use belt filters. Instead, they rely on what’s called a tailings storage facility.

“This is effectively a large dam where waste material is pumped, allowing solids to settle while water is recovered and pumped back to the plant,” Upward Spiral 1471 metallurgical manager Thabang Masuku explains.

This approach requires considerable infrastructure, ongoing pumping and large areas of land and presents environmental risks, including potential ground contamination and water loss through evaporation, Upward Spiral avers.

It notes that the belt filtration system works by pulling slurry directly onto the belt filter inside the plant, while vacuum suction removes the water almost immediately, producing a filtered cake. That water is stored in concrete dams at ERPM and can instantly be reused in the process, rather than being pumped long distances and recovered later, the company highlights.

Upward Spiral says that, because the entire process takes place within the plant, there is minimal ground interaction and therefore a reduced risk of environmental contamination.

“Unlike traditional tailings facilities, which require extensive lining, ongoing management and long-term rehabilitation, this approach eliminates the need for large external storage infrastructure and the associated environmental risks,” the company posits.

“With this system, the only material that leaves the plant is the filtered cake. The water is continuously reused. There is no need for large dams, no risk of seepage into the soil and no evaporation losses,” Masuku points out, adding that the filtered cake itself can be sent for further processing, or it can be neutralised to remove any residual chemicals and then used responsibly to rehabilitate mined-out areas.

Upward Spiral says the belt filter is also more efficient and cost-effective.

“From an operational perspective, you save time and energy because everything happens in one closed circuit. You don’t need to pump material long distances, you don’t need heavy machinery to build and maintain tailings dams and you reduce overall water and power consumption.

“Although we are still finalising the detailed cost analysis, we expect this system to represent a significant reduction in operating expenses compared to conventional methods,” Masuku informs.

Upward Spiral says it is the first gold plant in its region to implement belt filtration at this scale.

“Other operations may use smaller filter press systems, which work on a similar principle, but those are not suitable for large volumes. The belt filter is designed specifically for high-throughput industrial applications like ours,” Masuku asserts.

The company expects to recover about 40% of the total processed water immediately through the filter.

“Because the filtration takes place indoors, we can even cover the system to further reduce any losses. Essentially, it allows us to operate in a near-closed water circuit, which is a major advantage in water-scarce environments,” Masuku highlights.