CDC taps centrifugal pumps market successfully – and responsibly
Dust Buster News

Whilst the majority of continuous miners in the coal mines are equipped with a positive displacement pump to provide sufficient water at a pressure of 20 bar at the nozzles on the spray fan systems, for some mines - either because of a natural head of water or because the water supply is boosted – a multi-stage centrifugal pump could be a viable alternative.

CDC’s six-stage centrifugal pump driven by a hydraulic motor will provide 120 lit/min of water at approximately 13 bar and, provided that the incoming supply is in excess of 15 bar at 120 min/min flow, then the combined heads will be sufficient to provide a 20 bar pressure at the nozzles and allow sufficient for pressure drops through the filters and system.

Before supplying a centrifugal pump for pressure boosting on the CM, CDC field support engineers survey the sections involved and produce a pressure flow curve for the water supply to the section. The pump characteristics are added to this and a typical system resistance curve imposed on the graph to arrive at the total system operating point. Provided this meets the requirements of the system, then a centrifugal pump can be used instead of a positive displacement pump.

If the supply characteristics at the section are insufficient, then a positive displacement pump has to be used. Unfortunately, some mines have been sold centrifugal pumps when in fact insufficient incoming pressure is available and this has given the pumps a bad reputation in some quarters.

Sasol Coal’s Secunda mines initially bought 20 centrifugal pumps from CDC late last year as part the R2,6-million contract awarded to the company to upgrade the dust suppression systems on all the continuous miners at the mines which had not yet adopted its three-fold integrated system comprising CDC wet fan scrubber boxes. A further 10 units have been purchased by the Sasol Coal mines this year, while Ingwe’s Gloria Colliery near Witbank has purchased a total of eight to date and leading CM suppliers Joy Manufacturing has bought four.

The CDC centrifugal pump achieves the performance in six stages as opposed to eight stages required by other pumps on the market. It is also very competitively priced at about two-thirds of the price of its competitors and is superior in design and performance.