The Bowen Basin is an area of coal reserves and mining related communities that extends across approximately 60,000 square kilometres of central Queensland, from the town of Collinsville in the north to Theodore in the south.
It is the largest coal reserve in Australia and the 34 operational coal mines within the reserve extract over 100 million tonnes annually. The Bowen Basin reserve represents some 83 per cent of the State of Queensland’s coal production and is a vital source of export coal to meet global demands.
In much of Australia and the world, longwall top coal caving technology is used to mine coal at depths of between 400 and 530 metres below the surface. It is considered a safe and reliable method of underground coal mining.
In one particular mine in the Bowen Basin, the ability to mine along the coal seam is dependent on the efficient and reliable underground dewatering and drainage.
Since 2008, Grundfos SP77-22 bore pumps have proven to be a reliable and integral part of the mine’s overall dewatering and drainage strategy.
The Mining Company involved approached Grundfos Authorised Dealer Dowdens Pumping & Water Treatment, headquartered in Mackay, to develop a design to efficiently extract water from the mine and ensure safe operations. The design includes two Grundfos SP pumps in separate boreholes and in close proximity, to provide redundancy or duty/assist. The duty / assist operation allows for additional water volume to be removed helping to prevent underground flooding and any subsequent interruption of mining operations.
The solution involves drilling the bore holes from the surface down into the lowest point of the flooded mine workings after mining has advanced along the coal seam, in a steady incline away from the bore location. The workings are totally flooded and void of air, controlling any explosion risk. This lowers the explosion hazard classification allowing for standard Grundfos SP pump and motor to be used.
The Grundfos SP pumps are lowered into each bore hole, one column at a time until the exact depth is reached using a combination of makeup columns. The borehole depth is 280 metres. A submersible pressure transmitter is attached to the column at a pre-determined depth level. This monitors the water table level in the bore hole and is connected directly to the SP Control Panel.
There are now six dewatering locations and more to come as the company’s longwall mining operations advance within the area.
The mining company involved commented that, “The pumps that have been removed for servicing have generally repaired well (mechanically), which is a testament to the product operating in these aggressive conditions".
Grundfos has a wide range of energy-efficient submersible pumps that can handle flows to 470 m3/h and each pump size is available with an optional number of stages to match any duty point. In addition to quality submersible pumping solutions, Grundfos can provide a range of reliable pumps and pumping systems including end suction pumps, variable speed pumps, multistage pump etc. for a wide range of mining applications.