A new approach to estimating aerosol particle escape fraction from operational open-pit mines

We have developed a new approach for estimating the escape fraction of aerosol particles produced by mining operations in deep open-pit mines. The method requires simultaneous vertical profiles from the mine floor of horizontal winds and backscatter profiles that are obtained from a scanning Doppler wind LiDAR and a laser ceilometer. The method is adapted to individual mines of different shape and volume through computations of mine drainage area and volume as a function of height for a control volume that is defined by a ridgeline that circumscribes the open pit. Volumetric computations are made from an accurate topographic map. The mathematical approach considers that changes to the aerosol loading in the mine are produced by horizontal outflows of aerosol through passes and over ridge lines on the control volume circumference, vertical mean and turbulent fluxes through a horizontal surface at the top of the control volume, deposition of aerosols within the mine, and inputs of aerosols from a variety of mining operations within the control volume. The conceptual and mathematical approaches will be described and the Bingham open-pit copper mine near Salt Lake City, Utah will be used to illustrate the topographic computations. The advantages and disadvantages of the new approach will be considered and major assumptions will be enumerated.