Continuous Miner Technology in India Over the Past Two Decades: A Review of Geotechnical Issues and the Way Forward

Abstract

Continuous miner technology was introduced in India in 2002 at the Anjan Hill Mine, and the coal seam, situated at shallow depth below hilly terrain, was extracted satisfactorily. This technology attracts the mining professionals across India as it has emerged as a promising solution for enhancing underground coal production with safety. Over the past two decades, 57 continuous miner packages have been deployed in 41 out of 186 underground mines across Indian coalfields, at depths ranging from 33 m to 435 m. The adoption of this technology is expected to expand further to support the national target of achieving 100 million tonnes of annual underground coal production by 2035. Operational performance indicates that average daily outputs of about 1,000 tonnes and 1400-2,000 tonnes during development and depillaring operations, respectively, can be achieved with this technology. At a couple of mines, this technology performed unsatisfactorily due to adverse geological conditions. Structurally controlled instability is persistent, especially in the unsupported cut-out distance due to weak/laminated strata in the immediate roof. Roof instability in and around a pillar under extraction has been observed under the influence of hidden geological discontinuities, induced stress, undersized rib/snook, working below goaved-out panels, etc. Under such circumstances, the trap of continuous miners in the goaf, fatal accidents, and loss of coal experienced, which impact the safety, productivity, and performance of this technology. Improvements in geotechnical assessment are required to enhance the economic viability of underground mining, effective strata control, and mitigation strategies under different geo-mining conditions. This study presents a comprehensive review of the performance of continuous miner technology in Indian coal mines since its introduction. Based on the review, several mitigation strategies are proposed to address the identified challenges and improve the safety, efficiency, and long-term sustainability of the continuous miner technology in Indian coalfields.