PURPOSE:  The objective of this research is to reduce mine worker exposure to respirable coal and/or silica dust by increasing the dust capture efficiency of mine water spray systems.

RESEARCH SUMMARY:  Coal workers’ pneumoconiosis (CWP) and silicosis are debilitating and sometimes fatal occupational lung diseases that afflict mine workers at underground and surface mining operations. The number of mining deaths between 1990 and 1999 related to CWP was 15,036. From 1990 to 1999, there were 2,405 deaths related to silicosis. For 880 of the silicosis deaths, the associated industries were recorded on the death certificates with 203 (23.1%) attributed to coal and metal/nonmetal mining combined. For this same time period, the percentage of coal mine dust samples that exceeded the 2.0 mg/m3 dust standard was nearly 9%, while the percentage of dust samples exceeding the allowable silica limit for coal, metal, and nonmetal mining were 30%, 12%, and 7%, respectively. These data illustrate the severity of lung disease in mining and the inadequacy of control technologies for consistently maintaining compliance with the mandated dust standards.

Laboratory tests have been completed to quantify the air moving capability of different spray nozzles, as well as, the dust capture efficiency of these sprays for multiple operating pressures. This information was used to develop a water-powered scrubber that moves approximately 500 cfm of air with a high dust capture efficiency, yet operates at water pressures below 250 psi.

Future research will focus on using this fundamental spray characteristics knowledge to improve existing dust control systems and/or develop new control applications. Laboratory research work for improving the dust capture efficiency of coal mining machine mounted spray systems is planned for future testing in the full scale dust gallery. Successful technologies will then be tested at operating mine sites. Recently, arrangements have been made to conduct a dust survey in early spring at a dimension stone shop to evaluate a water-powered scrubber. This scrubber will be installed to evaluate its effectiveness for reducing silica dust generated by a rock cutting saw.

Planned project outcomes are to develop and demonstrate improved, user-oriented, spray systems for mining and cutting machines that can reduce airborne respirable dust by more than 30%. A measure of project outcomes would be to have these spray system developments adopted or implemented in a notable segment (30%) of the mining industry within 5 years of project completion.