Dust reduction method based on the volume of plastic zone and a comprehensive control technology for roadheader cutting

Roadheaders play a vital role in enhancing coal mine production efficiency, but they also generate a significant amount of dust during high-intensity cutting. To address this issue and make dust control more manageable, an approach was developed by adjusting the cutting parameters of the roadheader. This approach is based on analyzing the five stages of dust generation during pick penetrating into the coal, while systematically considering the relationship between the plastic zone volume and the tip angle of the pick. By reducing the angle of the cutting tooth tip and the rotation speed of the cutting head, the amount of dust generated would be decreased. Field experiments were carried out at a tunneling working face to investigate the variations in dust production under different cutting parameters. To control dust at the tunneling working face, a comprehensive dust control method was implemented, including external water spray, a wet dedusting fan, an air curtain, and an inductive full-section water curtain. Dust measurement points were established at the driver of the roadheader, 5 meters behind the roadheader, and 2 meters behind the full-section water curtain to assess the effectiveness of dust control at different locations. The results revealed that replacing the conical picks with a smaller tip angle (92° & 54 rpm) resulted in decrease of average mass concentrations of respirable dust (MRD) and total dust (MTD) with 18.5% and 9.1% lower than the original conditions. Additionally, reducing the cutting head speed (92° & 27 rpm) led to MRD and MTD reductions of 34.5% and 15.8% compared with the original conditions. After implementing comprehensive dust control measures, substantial reductions in MRD and MTD were observed at different locations. At the driver of the roadheader, the average MRD was reduced to 4 mg/m³, with a dust reduction rate of 90.6%. And the average MTD decreased to 20.5 mg/m³, with a dust reduction rate of 93.6%. At 5 meters behind the roadheader, the average MRD and MTD were reduced to 6.6 mg/m³ and 30.1 mg/m³, with dust reduction rates of 86.9% and 91.5%, respectively. At 2 meters behind the water curtain, the average MRD and MTD were reduced to 2.4 mg/m³ and 3.9 mg/m³, with dust reduction rates of 91.3% and 95.1%, respectively. These findings demonstrate the effectiveness of the proposed method in significantly reducing dust generation and ensuring a safer working environment.