Abstract
On mining sections using blowing ventilation, a machine-mounted scrubber is often required to maintain face dust levels below 2 mg/m3. The quantity of airborne dust entering a scrubber is directly related to the quantity of air drawn through the scrubber. Due to loading of the scrubber filter, scrubber air flow can decrease significantly during mining. Excessive loading can also cause the fan to be starved for air, resulting in a condition called aerodynamic stall. To restore scrubber flow, the scrubber filter must be removed and cleaned. During the mining operation, it is difficult to determine if scrubber air flow has decreased significantly until the fan stalls. Observation of scrubber performance is particularly difficult when the mining machine is operated by remote control. Periodically, scrubber flow readings can be taken. However, most air flow monitoring equipment will be damaged if left in the wet and dirty environment of the scrubber duct for long periods of time. Experiments were conducted to determine if static pressure at the fan inlet, differential pressure across the scrubber filter, or scrubber fan motor current could be practically used to monitor scrubber flow. Scrubber filter loading was simulated under laboratory conditions. The selected variables and scrubber flow were monitored concurrently. Results showed that each of the variables could be used to estimate scrubber flow. By continuously providing this scrubber flow information to underground face workers, maintenance can be performed before scrubber flow becomes too low and fan stall occurs. Insufficient air flows could result in methane accumulations in the face area, which increases the potential for a face ignition.