Highwall mining in India -- part-I: design methodology and review of performance.

Highwall mining technology is the modified version of earlier auger mining. It facilitates recovery of locked up deposit in open pit highwalls, below villages, road, and other surface structures. Mining operations consist of driving series of parallel roadways at intervals in a planned way to recover considerable amount of coal from the highwall. The method offers great safety to mining personnel because of remotely controlled highly mechanised mining operations and unmanned extraction drivages. Although key to successful operations is scientific design of web pillars that support these drivages, optimum design to increase recovery is the main requirement. Design methodology includes estimation of long and narrow pillar strength through CIMFR empirical equation with some modification and application of numerical simulation to consider multi-seam interaction, pillar stress, etc. This methodology' has been utilised for highwall mine design at Opencast Project II (OCP-II) mine of Singareni Collieries Company Limited (SCCL) and Medapalli OCP (MOCP) of SCCL by CIMFR. Although, mining operations at both the sites are successful, performance analysis reveals that ooccurrence of roof fall, breakdown on account of geological disturbances and poor power supply, exposure of stone bands in the seam, working in cross gradient, etc., are some of the issues that has jeopardised full production capacity of the CHM. The highwall mining design methodology and performance analysis at couple of sites are discussed in detail in this paper. [ABSTRACT FROM AUTHOR]