Dust concentrations around coal stockpiles

Abstract

One of the sources of airborne dust from operations at coal terminals is wind erosion of the stockpiles. The condition of the stockpile, whether it is being worked (a live stockpile) or at rest (dead storage), is of prime importance. A further important set of variables is formed by the meteorological conditions. To predict the dust concentration in the air around future coal terminals due to wind erosion, we have used a computer program developed some time ago for describing the dispersion of heavy gases in the atmosphere, adapting the program to take into account the fall-out of particles as a function of their size. The input of the program comprises the geometry of the stockpile area, the atmospheric conditions and the source strength of the stockpile. To provide data on the source strength as a function of atmospheric conditions, measurements were performed near a number of existing stockpiles in various countries and regions. Dust concentrations in the air around the stockpiles were determined with a high volume air sampler. The dust collected on the filters was analysed and the particle size distribution determined. The results obtained were compared with predictions from the computer program for various input conditions. In this way the source strength was derived. When this source strength is inserted into the computer program, predictions for a projected coal terminal can be made. The results of the calculations predict the dust concentrations in the surrounding area under various conditions. Some typical results are presented.