Using the incorrect equipment in pump applications is a key issue that a number of mines need to address, as it results in unnecessary and costly failures, says electric pumps and borehole motor supplier Ernest Electro Engineering MD Gert Schwaecke.
He maintains that for the managers who buy the pumping equipment there is often a disconnect between the purchase and the practical implications of using the pumps. “Pumps are some of the most misunderstood pieces of equipment in South Africa,” he avers.
Mines will often buy pumps and pump motors from different suppliers, which can result in compatibility problems. In many cases, inadequate borehole piping is installed that cannot handle the stresses of the application. In such cases, the equipment is easily damaged and must be replaced, resulting in unnecessary costs for mines.
To address this problem, Ernest Electro Engineering provides a holistic product offering, supplying pumps with a motor, controller and pipe that are carefully designed for the application at hand. As a result, Schwaecke states that, at some sites where the company’s units have been installed, they have lasted for as long as ten years without incident.
Robust Product Offering
“The pipe is the key to ensuring the pump motor lasts in the borehole,” Schwaecke stresses, adding that the borehole pipes supplied by Ernest Electro Engineering are ideally suited to applications that require installation at great depths. The pipes are made out of stainless steel to prevent corrosion and pump cabling can be secured along the pipe.
“In most installations, the cable, which, at 140 m, translates to almost 1 t of weight, simply hangs. “Thus, cabling is often ripped out of power boxes. With our pipe, the cabling is strapped down every 2 m, ensuring that its weight is supported for the entire length.”
The company completed a project in July for a prominent gold producer in South Africa, installing two 300 kW borehole pumps at a depth of 3 000 m underground, which extended a further 150 m down. These pumps will dewater the mine, enabling the company to reach the gold deposits currently under water.
Last year, Ernest Electro Engineering also introduced a semidirect current submersible motor, manufactured by German pumps supplier Oddesse, which is 30% more efficient than other motors currently on the market. Schwaecke explains that the motor is designed with a permanent magnet rotor and normal alternating current winding, which produces a higher torque and improves the performance of the motor.
Subsequently, a 55 kW motor could, for example, be used on a 75 kW pump, which results in an energy saving of about 30%, he adds. In addition, the motors are equipped with a variable speed drive, enabling the user to adjust pump speed at the touch of a button according to the application.
Despite these significant advantages, Schwaecke notes that demand for the motor in South Africa has been low, owing to the downturn in commodities prices, which has made the mining industry hesitant to invest in capital equipment. In addition, he points out that many mines are sceptical about investing in new technology, preferring instead to continue using equipment that is familiar to them.
The motors are, however, being used extensively in water systems in Germany, and Schwaecke believes that, once they have proven themselves locally, the motors will become standard in the South African mining industry.
Ernest Electro Engineering also supplies a submersible motor that can lie horizontally in a body of water, mounted underneath a float, to pump water to a chosen location. Schwaecke highlights that this produces large cost savings, compared with traditional centrifugal pumps that require more complicated engineering.
The installation of this submersible pump takes only a few hours, while traditional pumps can take a few weeks. In addition, the pump requires no maintenance, as there are no wearing parts such as bearings or mechanical seals. It is also not prone to mud blockages like return valves used in traditional pipes and, with just 55 kW, can pump the same amount of water as a 75 kW pump, making it more energy efficient.
At present, the pump has experienced great success in supplying water at diamond mines in Witbank, Mpumalanga, and the Northern Cape, as well as to grape farms along the Orange river, in the Northern Cape.