Kestrel longwall superintendent Paul Bettinzoli began the trial by identifying where on the longwall face and throughout the work area the dust was generated.

This was achieved through the use of portable and fixed gravimetric pumps, supplied by Riskguard Services, and a miniram, supplied by SIMTARS, were positioned at different points along the longwall face.

The gravimetric pumps sampled over a shift period and provided data of the dust particulates an individual worker was inhaling.

The miniram was used as a spot sampler and gave an instantaneous readout. Ten positions were tested including the air entering the mine, points progressing across the face and then around the shearer.

Tests found the shearer generated about 50% of the dust, the shields 25%, and the air entering the longwall area and the BSL crusher were also generators.

“Armed with the data we then put in place some operating practices that reduced the exposure of people to those dusty areas,” Bettinzoli said.

“For example, a person is allowed three hours on the tailgate side of the shearer during operation. With our measurements we have been able to ascertain if a person did that he would still be under the maximum allowable concentrations for dust.”

Bettinzoli also trialed a citrus additive on the shearer water pump system which resulted in up to a 70% reduction in respirable dust.

The additive, Dustcon manufactured by Polo Citrus Australia, is a by-product of the citrus process and is refined into liquid form that is injected through a dosing pump. This allows for the modification of the injection rate into the shearer water supply.

A pump system purchased from Senior Thermal Engineering Australia, who also supplied the citrus additive, has now been installed at the services cut through.

Bettinzoli estimated the cost at $150/day based on a shearer operating time of 16 hours a day and a capital cost of $3,500 fully installed and calibrated.