Gallery monitoring in blasting gallery panel during depillaring - A case study

Abstract

About 50% of coal reserves in India are in seams thicker than 4.5m, which come under the category of thick seams, the exploitation of which is consistently posing challenges to the mining engineers. Extraction of thick seams by conventional hand section method is neither productive nor effective from the conservation point of view. The percentage of extraction by hand section mining in thick seams is as low as 25-30%. Sand stowing for working of thick seams cannot be considered as an option because the cost is prohibitive. Sand has become an increasingly scarce commodity along with timber. Blasting gallery (BG) method of depillaring thick coal seam is one of the productive methods with high production, productivity, economic and conservation. In this method, stability of workings and easily cavability of goaf is very important for safely extraction of pillars, safety of men and machinery. In this paper, strata monitoring data of load cells in galleries of a blasting gallery panel, where spoiling in pillars, instability of galleries and displacement of supports are monitored and analyzed during depillaring in specific geo-mining and working conditions of a underground mine in southern part of India.