Ultrasonic Water Spray Systems for Respirable Dust Control in Underground Coal Mines

Respirable coal mine dust (RCMD) is a hazardous material byproduct of daily mining activities, posing a significant occupational hazard for mining workers. Long-term exposure to RCMD can lead to chronic pulmonary diseases. The most critical one is the Coal worker’s Pneumoconiosis (CWP). The mining industry has implemented different dust control methods, one of the most popular ones being water sprays. However, current water spray systems have low efficiency in suppressing sub and supra-micron coal dust particles since these particles’ characteristics (such as physical property and wettability) significantly differ from those of larger dust particles. This study investigated the potential of ultrasonic nozzles, which produce smaller water droplets than traditional air-atomizing nozzles in capturing RCMD particles. Surfactants were added to the water source to enhance the dust capturing efficiency of the droplets. For the research, different references of ultrasonic and air-atomizing nozzles were selected and installed inside a wind tunnel, simulating ventilation conditions inside underground mines. Using an aerosol generator, dust samples from Northen Appalachia region were injected into the tunnel, and dust monitoring equipment was installed at the tunnel’s measuring area to record the data. The results showed that the ultrasonic nozzles better control respirable dust than the air-atomizing nozzles.