Deposition of respirable coal dust in an airway. Report of Investigations/1986

Because of the inherent safety problem associated with the deposition of airborne respirable dust onto the floor and other airway surfaces, the Bureau of Mines investigated the rate of reduction of airborne respirable dust in an airway due to deposition of the particles onto the surfaces of the airway. The effects of relative humidity and air velocity on the deposition rate were examined. It was found that the deposition rate was comparable in magnitude with the Stokes sedimentation rate and that it was independent of relative humidity. However, near the dust source the deposition rate depended significantly upon the air velocity, with such dependence decreasing with increasing distance from the dust source. These results suggest that deposition, though comparable with the Stokes sedimentation rate in magnitude, does not follow a simple Stokes-type process, and that the process of deposition remains to be explained.