Measurement of Coal Dust and Diesel Exhaust Aerosols in Underground Mines.
Rubow-KL; Cantrell-BK; Marple-VA
NIOSH 1990 Sep:645-650
Studies were made of diesel and mineral dust aerosols in the laboratory and in five underground coal mines. The studies used size selective sampling and chemical mass balance (CMB) modeling as part of a United States Bureau of Mines evaluation of new sampling methods for measuring diesel aerosol in underground coal mines. The Micro-Orifice Uniform Deposit Impactor (MOUDI) was studied in the laboratory for its ability to determine mass concentration of diesel exhaust aerosol from size distribution of a mixed aerosol of diesel exhaust and coal dust. The technique modeled aerosol size and operated on the premise that diesel exhaust was predominantly submicron and mineral dust was mostly larger than 1 micron. The mixed aerosol revealed bimodal distribution, with mass median aerodynamic diameters of 0.15 micron for diesel exhaust and 3 to 10 microns for coal dust. Mine tests were conducted in three mines using diesel haulage equipment and two using electric equipment. The MOUDI was used for size distribution measurements at air intake entries, conveyor beltway entries, air return entries, and haulage ways. A dichotomous sampler collected aerosols for CMB calculations. Modal analysis from MOUDI data was compared with CMB analysis. Diesel emissions predominated (75 to 90%) in submicron mode aerosol measurements in diesel operated mines, and coal predominated (up to 92%) in coarse aerosols. The minimum between the modes was at 0.8 micron. A personal diesel sampler was developed which used an inertial impactor for size separation of respirable aerosol at 0.8 micron and an after filter for gravimetric analysis of smaller material. A detection limit of 0.3mg/m3 was expected for a 2 liters per minute flow rate and gravimetric analysis to within 0.1 milligram. The authors conclude that size selective sampling is effective for measuring diesel aerosol concentrations in underground coal mines.
Workplace-studies; Laboratory-testing; Coal-dust; Diesel-exhausts; Coal-miners; Underground-mining; Mineral-dusts; Aerosol-sampling; Analytical-models; Aerosol-particles; Measurement-equipment;
Proceedings of the VIIth International Pneumoconioses Conference