Selecting the Optimal Borehole Drilling Pattern for Methane Drainage in Underground Coal Mining: A Case Study in Iran

The emission of gas from the coal seams is one of the most important issues during the underground coal mining operation. Each year, coal gas emission from the underground stopes leads to the death of a large number of miners and is one of the biggest threats to workplace safety. In addition, ventilating and releasing coal gas outside of the mine is too expensive and, in most cases, might be impossible. Therefore, it is necessary to increase gas emissions and improve the efficiency of methane drainage for securing the mining workplace. The main aim of this paper is to investigate the capacity of the drainage system in the Parvadeh Tabas Coal Mine, Iran. For this purpose, the effect of the specification of the drilling pattern such as the length and drilling direction of the drilled boreholes on the methane gas concentration was investigated. The results of this study show that, with the change in the length of the borehole and the angle of the boreholes according to the axis of the tailgates, the volume of the methane drainage changes, significantly. The boreholes with lengths between 60 and 80 m drilled in lines with 16-degree division from a line perpendicular to the tailgate have the highest methane concentration.