Pump Design And Its Effect On Mine Safety And Efficiency

The technology involved in coal mining around the world has advanced a great deal over the years, especially in terms of improving the health and safety of the miners

by Michael Sherman | Sunday 22 March 2015

At the same time mining efficiency and production rates have also improved.
Pumps, in their many different designs, perform a large number of vital tasks within the mining industry and as such they can be responsible for certain aspects of mine safety. However, with so many pumps in operation they can also make a considerable contribution towards improving the efficiency of the mine, especially in terms of energy consumption.

Mine safety, whether above or below ground, is the highest priority for all operators and maintaining a high standard requires considerable effort from all parties involved. This includes the manufacturers of equipment that forms part of the safety apparatus, requiring them to meet stringent performance criteria and successfully complete extended periods of testing.

With ever-tightening margins, the efficiency of individual pieces of equipment as well as that of operational and maintenance processes becomes more important. Making the right decision in terms of pump design can produce significant benefits for the safe and efficient operation of the mine.

Slurry pumping
Slurry pumps and pipelines form a crucial link between the mine itself and the processing and shipping operations. As such, the pumps must perform reliably in order for the mine to maintain operations. However, due to their size, energy consumption can be considerable and so improvements to their efficiency can have a substantial impact on operating costs.

The minerals are transported in suspension, in many cases over very long distances and the pumps must be designed to cope with large solids as well as corrosive fluids. These very harsh working conditions demand regular maintenance procedures to be conducted in order to keep the pump operating at its most efficient.

More recent designs are improving maintenance accessibility as well as using more durable materials to improve wear resistance and efficiency. With the aid of more sophisticated computer design systems, the development of slurry pumps is set to achieve efficiency levels close to those of clean water pumps.
Maintenance efficiency is also being improved with the introduction of condition monitoring technology which provides an early warning to the maintenance engineers about a potential issue. By addressing these before they develop into a serious breakdown, the downtime is greatly reduced, further improving the operating efficiency of the pumps.

Dewatering operations
Keeping any mine dry is a crucial aim for the operators and should form one of the key health and safety targets within the organisation. As such, the dewatering aspect of the mining operation requires very high levels of reliability which depends on selecting the most appropriate design and construction for the application in question.

For most requirements, the centrifugal pump remains the tried and tested solution. However, the need for improved efficiency and lower operating costs has led to some operators moving away from traditional centrifugal pumps and opting for alternative technologies such as oscillating discharge pumps.
As underground mine depths increase so the dewatering pumps have to be specified to cope with the new challenge. This can often come in the form of multi-stage, high pressure units, operating at around 100 bar, which are capable of maintaining the desired water levels.

All pumps and their associated pipework are affected by the fluids that they are required to transport, with solids content and pH posing a constant threat to reliable performance. Advances in materials technology have seen great improvements, with the use of chrome steels, duplex steels and high quality elastomers being used for more acidic applications.

In some applications, deposits can build up in the pipework which, if not resolved, can cause increased friction losses and therefore additional energy costs and a reduction in energy efficiency. One solution is to modify the pump arrangement to increase the fluid velocity, causing a scouring action to be created and, if properly managed, the rate of deposition can be equalised with the scouring rate.

Although this may increase the energy costs in order to attain the increased fluid velocity, this should be balanced against the maintenance costs of replacing or cleaning of all the dewatering pipework on a regular basis. These costs should also include the figures for lost production if the mine cannot be safely operated without the system under maintenance in operation.

More recent developments have seen the introduction of on-board electronics in dewatering systems designed to help with energy saving and reducing pump wear. Pump manufacturers are pursuing design improvements that can reduce the Total Cost of Ownership (TCO) and improve reliability.

Roof support systems
While the dewatering pumps manage with water levels, so it is equally important to ensure that the roof of an underground mine remains in position while the minerals are being mined. This responsibility falls to the roof support systems that are powered hydraulically by a number of high pressure pumps.

The principle of longwall mining is the use of a large cutting head or shearer which traverses the coal seam breaking it up and depositing the coal onto an armoured conveyor to transport the coal away from the face of the mine. This operation is protected by a series of hydraulic roof supports which prevent the mine roof from collapsing by applying huge pressures to support the rock above.
Each roof support is capable of independent movement so once the shearer has passed by, the support can lower itself away from the roof and advance forward to fill the space left by the shearer. In this way the roof support system maintains a safe haven for the miners and their equipment to operate in, all the time moving forward as the coal seam is mined and allowing a controlled collapse of the roof.

The efficient operation of the roof support system directly affects the safety and productivity of the mine; any down-time on the system in such a difficult operating environment would be very counter-productive. The reliable performance of these systems systems is essential if the client is to maximise output from the mine and see a return on investment.

Within the mining industry RMI Pressure Systems has a reputation for supplying some of the most reliable high pressure pumping systems available. With pumping stations being used in safety critical functions it is essential that the reliability is beyond question; requiring months of continuous testing before being accepted for operational duty.

RMI also has a policy of continuous development of energy efficient products, which has led to the introduction of the ODIN (On Demand Intelligence) control system. This system uses a range of data supplied from equipment used in the process of continuous longwall mining and uses it to calculate the changes in demand for hydraulic fluid before they occur. In this way ODIN can modulate the pump speed and change the flow and pressure characteristics to meet demand in the most responsive way possible.

RMI's impressive reliability is ensured by using only the best quality components and materials and manufacturing to exacting tolerances, to deliver pumps using the latest design techniques. For over 100 years RMI has been supplying innovative, practical solutions, backed by a long history of engineering expertise and proven by the large number of mining operations that rely on its products across the world.


Michael Sherman
RMI Pressure Systems Ltd
+44 (0) 161 274 2451

Sunday 22 March 2015 / file under Engineering | Mining