Design of blasting patterns to induce effective caving in continuous miner depillaring panel – a case study

Abstract

An innovative scheme of induced caving by blasting was adopted in the depillaring continuous miner panel CM₁ of Jhanjra Colliery of Eastern Coalfields Limited, a subsidiary of Coal India Limited. Initially, the blasting pattern was designed with respect to underground workings and later with respect to the surface, vertically above the panel, to facilitate effective caving. The natural caving was delayed due to the presence of three hard-rock beds of more than 5000 cavability index in the immediate roof of the R-VI seam in addition to the oversized left-out standing pillars kept during coal extraction in the panel, which provided extra supports to the hanging roof-rock in the goaf. To mitigate the situation, the design parameters were meticulously planned and implemented for successful blasting operations, which led to effective caving in the goaf and enabled successful extraction of the coal from the panel maintaining the required level of safety and productivity.