Peristaltic pumps use less water, while traditional centrifugal pumps lose efficiency when the slurry has a specific gravity (SG) of 1.3, or 30% solids or more. Peristaltic pumps can efficiently circulate slurry with SGs of 1.6 to 1.8, or with up to 80% solid content.
Pumps supplier Verder Pumps South Africa stocks a variety of peristaltic pumps specifically designed for mining applications and states that, owing to their low SG limitation, slurry pumps have significant process demands.
The company points out that, on a plant processing slurry at 75 t/h containing 65% solids, every time a peristaltic pump replaces a process slurry pump, it saves over 1 100-million litres of water a year because of the slurry pump’s inefficiency.
The company explains that a peristaltic pump undertaking the same application requires less than 25% of the process water of a slurry pump.
On the same 75 t/h plant, on thickener underflow duty at full flow, a VF125 peristaltic pump uses around 35 kW, whereas a normal slurry pump needs over 70 kW, resulting in an energy saving of over 50%.
“Power rationing is a concern for many established mines. “At new developments, the infrastructure costs to import power can be considerable and can even cause significant delays and generate considerable nonmining environmental opposition,” Verder explains, noting that the peristaltic pump reduces yearly operating power demand by over 210 MWh in this application.
The company points out that peristaltic pumps also improve downline efficiency and reduce the overall plant size. Pulp density is critical to optimum plant performance; increased solid content can reduce the number of post thickening filter stages, saving on the initial capital cost and reducing the footprint of mineral processing operations.
Peristaltic pumps further reduce mining’s environmental impact. Many mineral recovery processes use cyanide-based leaching techniques, especially where gold is a key mineral.
“Cyanide has many adverse environmental consequences, including polluting the land surrounding the plant, contaminating aquifers and decimating life in water courses. The traditional dosing solution, progressing cavity pumps, has integral seals requiring regular replacement and represents a clear leakage risk,” the company explains.
Verder highlights that peristaltic pumps are seal-less and have a much lower contamination risk.
Peristaltic pumps also offer a gentle pumping action, which is ideal for biooxidation techniques, as it limits damage to fragile cell cultures. The Biox process uses a live culture to free gold from sulphide ores. This opportunity for reduced cyanide use, moreover, therefore, also improves process yields.
Further, the gentle pumping action decreases the amount of reagent use, lowering acid mine drainage waste treatment costs.
“Conventional high-shear technologies, such as progressive cavity or screw pumps, significantly increase reagent use, which increases operating costs and raises post-processing costs, owing to flotation reagent carry-over.”
Similarly, residual reagents can increase the waste remediation cost or increase the environmental damage from tailings dams or their resultant groundwater pollution.
Peristaltic pumps are also resistant to abrasion, which further lowers maintenance costs, compared with slurry pumps, which use impellers made from expensive and nonstandard materials and have service lives that are measured in days.O
n a peristaltic pump, only the rubber hose is in contact with the pumped liquid, the service life is measured in months – therefore, reducing pump downtime. As the hoses used can be changed on site, a peristaltic pump’s maintenance hours are reduced.
The company adds that to pump highly acidic slurries, hoses are made from several standard elastomers, each proven in the mining environment to withstand process chemicals, while also not requiring the use of expensive exotic metal impellers.When
using a Verder peristaltic pump, production costs and downtime are significantly reduced, providing a more cost- effective process, concludes the company.