Experimental study on particle size distribution characteristics of coal with different hardness under impact crushing

In order to explore the particle size distribution characteristics of lump coal after crushing with different hardness under impact crushing, the impact crushing experiments of four different hardness lump coals were carried out by using the Protodyakonov coefficient measuring device. The experimental results show that the crushing energy is linear with the newly added surface area after the lump coal is broken, and the converted diameter is inversely proportional to the crushing energy. The lump coal has self-similar characteristics after crushing, and its fractal dimension can reflect the crushing degree of coal. The larger the fractal dimension, the better the fracture effect, and the solidity coefficient f is linear with the fractal dimension D. During the crushing process, the large particles are buffered by the presence of surrounding small particles, so that the smaller particles are preferentially destroyed due to extrusion, and the buffering effect of small particles enhances the ability of the large particles to resist crushing, so the smaller particles are more likely to be broken.