Investigating the shape and size distribution of dust in mechanized longwall method in Tabas coal mine

When the average size of coal dust particles is reduced, risk of explosion as well as probability of emergence of numerous diseases is increased. To find the rate of negative effects in mechanized longwall mining face, the amount of spread coal dust and the scattering manner of particles in each part of the face and tail gate are investigated. Accordingly, 19 samples were taken from the face and tail gate of Tabas mechanized coal mine. Then, using the Zetasizer device and TEM (Transmission electron microscopy), the samples were analyzed and their shapes were determined, respectively. Results showed that shape of the particles was almost spherical and their size followed Rosin–Rammler distribution in the tail gate and along the longwall. In the face, since there was no opportunity for the deposition of coarse particles, some disturbances were observed in their distribution. At the beginning of the tail gate and close to the face, as the height increased, coarser particles were observed, which deposited after passing through the tunnel and getting away from the face. Considering these results, the aggregation and sequestration regions of dust could be found and the ventilation system can be modified. Also, more suitable solutions can be adopted for dust control or more advanced equipment can be proposed for miners in terms of confronting these particles in their working environment.