Particle correlated characteristics of coal rock crushed by disc cutters

The morphology, particle size distribution and dust production of crushed coal rock formed by the interaction between mechanical cutting tools and coal rock are crucial indicators that reflect rock breaking efficiency and operation safety. This study conducted a vibration cutting experiment with cutting thickness, vibration frequency, feed speed and disc inclination angle as major parameters to investigate the macro-micro morphological characteristics of the body and the crushed body after coal rock was crushed by disc cutters. We established an entropy characterization model of block size, verified its feasibility of measuring the degree of fragmentation and discussed the block size distribution of the crushed body. We used laser particle size analyzer to detect the dust particle size distribution of floating dust in the process of crushing coal rock by disc cutter to analyze the characteristics of dust production. The sensitivity of block particle size and dust production rate was investigated in terms of range and contribution to analyze the correlation between crushing characteristics and rock breaking parameters. Results show that the structural characteristics of the wedge surface and the tooth edge of the disc cutter gave the crushed coal rock body a crescent section and intermittent cutting marks. In the crushed body, the large coal rock was mainly in the shape of a flaky crescent, where crushed coal rock with a particle size longer than 8mm took up a high proportion. Cutting thickness exerted significant effect on the proportion of large coal rock, with a contribution rate of 73.11 %. Vibration frequency and the inclination angle of the disc were positively correlated with the degree of fragmentation of the coal rock. The particle size distribution of the crushed coal rock could be described by the Rosin-Rammler distribution function. The microscopic morphology of the dust particles was polygonal and nearly spherical.The increase of feed speed would aggravate the contact opportunity between the disc cutter and the coal rock, and its contribution to the dust production rate is 61.88 %. The increase of the vibration frequency led to an increase in the dust production rate. When the inclination angle of the disc increased, the contact area between the disc and the coal rock decreased, resulting in fewer opportunities for dust generation.