Centurion-based, family owned, pumping solutions provider Hazleton Pumps has patented a new pump technology that will dewater deep-level mine shafts more efficiently. The Hippo high head series submersible slurry pump system can remove acid mine drainage (AMD) water from flooded mine shafts in a series, with minimal limits on the depth at which the pumps can operate.

The system is ready to be marketed to the local and global market. “We realised that most of the mines, especially the local deep-level gold mines are already flooded,” Hazleton Pumps MD Thys Wehmeyer states. “And to evaluate the [mine] infrastructure already in place [for mining viability], we need to pump the water out.”

Currently, deep-level mines use a multistage horizontal pump system. There are a few issues that arise from this system, says Wehmeyer. Firstly, the costs of a permanent multistage pump station and high-pressure pumping are significant. Secondly, as horizontal multistage pumps cannot run dry and the inflow liquid supply is not constant, an underground dam or reservoir will be required for the pumps – also at significant cost.

In addition, if power at a mine were to fail, the pump station will be flooded and work would stop until the electric motors are brought to the surface, either repaired or replaced and then reinstalled, Wehmeyer points out. Another issue is the solids found in AMD water in the shafts, which will shorten the life of the pump, owing to the wear rate on the pumps parts and, in some cases, destroy the pumps, he continues.

Should multistage vertical spindle submersible pumps be used, only a limited volume of water can be pumped. This will increase the time needed to obtain the desired results.

Hazleton Pumps has designed and developed the Hippo system that uses the discharge of the first pump for the next pump in the series. “We started developing this series of pumps three years ago, and it was patented six months ago,” enthuses Wehmeyer. This pumping system can handle underground mine water contaminated with acids and containing solids, owing to the materials used to build the pumps as both acids and solids will wear down the parts, Wehmeyer points out.

How it Works

The first step in the system is to lower a Hippo slurry submersible pump into the flooded shaft to a point where it can work at optimum efficiency. Water is then pumped to the intake of a second pump, from where it is then pumped to a third pump and so on until the water reaches the surface or disposal area. The pumps are vertically spaced at intervals as required by the application so that the inlet pressure to the next pump does not exceed 1 bar, explains Wehmeyer.

“There are minimal limitations on the depth to which these pumps can be taken,” he enthuses. However, the mine’s lifting equipment might not be able to handle the weight of the pumps being lowered down the shaft one after the other, Wehmeyer claims. Another limitation is the amount of electrical power available: “If there is not sufficient power, a smaller pump will have to be used, which is less efficient,” he points out.

A major advantage is the materials used in the manufacture of the pumps, he continues. Several mines in South Africa, particularly the gold mines, have a high level of acidity. “Hazleton Pumps has developed the product in South Africa and every casting and part for the pump is manufactured in South Africa,” Wehmeyer notes.

As a result, Hazleton Pumps is able to vary and customise the materials needed for individual pumps, depending on the water quality and acidity level of a mine. The higher the quality of the water being less acidic, the cheaper the cost of the pump, he highlights. For example, stainless steel parts can be used for shafts that have a higher acidity or hardened chrome parts for shafts with a greater amount of solids.

Meanwhile, the pumps, which are exportable, have been sent to an oil sands operation in Fort McMurray, Canada, while two flame-proof pumps have been sold to an oil refinery in Houston, the US.

Wehmeyer maintains that the issue with exporting to North America and Canada is that they have different parameters, when it comes to mining. The mines in North America and Canada are not as deep as South African mines; therefore, the power and lifting requirements are different. Pumps for these markets also need to be larger to handle larger volumes efficiently.

“The Hippo pumping system will make the dewatering of deep-level mine shafts more effective and cost efficient,” he concludes.