Surface physical properties and its effects on the wetting behaviors of respirable coal mine dust

In the present research work, coal dust physical properties as well as its wetting behaviors were analyzed systemically. The influences of different surfactants on coal dust's wetting behaviors were also investigated and compared with deionized water. Research results show that the finer the coal particle sizes, the more complex the coal particle micro structures are, which may cause the poor wetting abilities. Among the three different coal dust samples, the wetting performance is poor for the coal with higher volatile content due to the easier release of volatile matter and the easier formation of gas film around the particle. The fractal dimension and contact angles are presenting perfect correlations. With the increase of the fractal dimension, the contact angle would increase correspondingly, which indicates a poor wetting performance. The wetting behaviors of coal dust could be greatly improved by adding surfactant in the deionized water. However, the species of surfactant and its contents in the solvent are the two important factors for dust wetting abilities enhancement. For the two selected surfactants, sodium dodecyl sulfate (SDS) may be a better choice and 0.2% concentrations are recommended during coal dust suppression applications. Based on the experimental results, a wetting dynamic model was built to simulate coal dust wetting process. The calculated values agreed well with the experimental results. (C) 2012 Elsevier B.V. All rights reserved.