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| Adjusting airflow through water-powered scrubber |
Background
Mining machine operators have some of the highest frequencies of overexposure to both respirable coal and silica dust. From 2000 through 2004, over 8,500 samples collected from operators of continuous miners by MSHA inspectors and mine operators exceeded the 2 mg/m3 respirable dust standard. Although water spray dust suppression systems continue to make significant contributions toward reducing dust exposure among miners, NIOSH has identified diminishing returns, and simple increases in pressure and/or quantity have not adequately provided the dust control needed to reach permissible exposure levels, particularly when dust standards are lowered due to excessive silica in the samples. To improve dust capture by water sprays operated at the pressures typically found in underground mines, NIOSH has developed a portable inline series spray scrubber to improve removal of localized airborne dust emitted at the source. Laboratory results show that the inline spray scrubber can move between 484 to 679 ft3/min of air and achieve 69% to 81% respirable dust capture efficiencies when operated at 250 psi. NIOSH laboratory and field research studies are continuing in order to optimize this dust scrubber technology.
Potential Outcome
Use of these portable scrubbers close to the source of dust generation on a mining machine is expected to reduce the amount of airborne dust resulting in reduced exposures for mining machine operators. This technology will also likely have applications outside of mining. For example, inline spray scrubbers could be used for a number of applications in mineral processing facilities. Laboratory tests of this concept should be completed in 2007, and information published in late 2007 or early 2008.