Research into the effect of gallery size on blast pull in underground coal mines

Purpose. To investigate the effect of gallery size on blast pull in underground colliery by drilling and blasting techniques. Methods. The study conducted in three different underground collieries namely A, B and C located in eastern part of India has been accomplished by solid blasting using milli-second short delay detonators and wedge cut pattern. The trial blasts were conducted in underground mines to investigate the effect of gallery size on blast pull. Findings. From the study it was found that the pull is related to the cross sectional area of the drive. It increases as the face size increases. This relation is obtained considering width of the gallery in the range of 3.0 – 4.8 m and height of the gallery in the range of 2.2 – 3 m. It is assumed that the angle of the hole and the length of the hole are optimum, charging and connections being appropriate. Advancement per blast round was found to vary from 0.8 to 1.5 m whereas average advancement per blast round was 0.98 m. Originality. This is a field study and the results are based on the data collected and analyzed on site. Although similar studies have been done by various researchers to improve the productivity of the mine for different conditions, the obtained results are condition, machinery, method and mine specific. Practical implications. This study is applicable for underground coal mine but can be extended in underground metal and tunneling projects for improving the blast pull.