On the transport of airborne dust in mine airways.
NIOSH 1990 Sep:56-63
Factors affecting the transport of airborne dusts in mine airways were examined. A mathematical model for predicting the behavior of dust clouds containing nonrespirable and respirable particles in mine airways was developed. The model assumed that the airflow in a mine was turbulent and that the dust particles were deposited on the mine floor by Brownian diffusion, convective diffusion, and sedimentation processes. Six experiments were performed in a former limestone mine converted into a laboratory and two were performed in the return airway of a longwall section of an active mine to obtain data to compare with the model predictions. Semianthracite and bituminous coal dusts having median particle sizes of 4.96 to 7 microns were dispersed by a fluidized bed type trickle duster at velocities of 0.838, 1.525, and 1.855 meters (m) per second. Centerline and cross sectional dust samples were collected by isokinetic samplers located at selected points up to 488m from the source. Floor samples of selected dust were collected every 100 feet from the source. Both predicted and experimentally measured airborne dust concentrations decreased rapidly with increasing distance from the source and approached an asymptotic value. The experimental concentrations decreased more rapidly than the measured concentrations. The experimental and predicted concentrations were in agreement for distances greater than 120m. The predicted and experimental floor deposition data were in good agreement, especially at distances of 60m or greater from the source. The average dust concentration in an airway cross section was 75% of that at the center of the airway.
Diffusion-analysis; Airborne-dusts; Coal-dust; Mathematical-models; Underground-mining; Work-environment; Simulation-methods;
DHHS (NIOSH) Publication No. 90-108
Proceedings of the VIIth International Pneumoconioses Conference