Research on the Effect of Extinction Characteristics of Coal Dust on Visibility

A good knowledge of the reduction mechanism of visibility is fundamental to developing preventive strategies in coal mines. In this work, the Mie theory was selected for investigating the absorption and scattering of coal dust. A prediction model for evaluating the visibility was developed based on the extinction characteristics of coal dust. The optical properties have been discussed to simplify the model and clarify the relationships among the different wavelengths and diameters. Additionally, the variety of extinction coefficients can be reasonably used in guiding the calculated visibility under different conditions. The experimental results demonstrated that the reduction of visibility was attributed to the synergistic effect of the extinction of coal dust and droplet. For the field application of this prediction model, the relative errors of the calculated and measured visibility were 9.8 and 7.1% from models I and II, which reflected the small deviation between the two methods. The prediction model can accurately describe the visibility in mines due to coal dust pollution. The exploration results provide a significant reference for the development and application of air cleaning technology for increased visibility.