An innovative initiative to design a feasible mining method in the deepest coal mine of India

摘要

In the deepest coal mine of India, the geotechnical problems encountered in the past, sometimes insurmountable, had upset the applecart such that the workings were disused and waterlogged to the brim of the existing shafts. These problems were related to bumps, roof-sloughages even in existing developed galleries with associated problems of degree-Ill gassiness. Wongawilli method, as practiced in Australia, has been modified to suit the prevailing geo-mining conditions of India using Continuous Miner (CM) deployment with stowing as goaf treatment. This method has been tried in the same form or as a variant of it with caving only and that too outside India.Empirical and numerical modelling approaches have been briefed in this paper to design this method of mining with sand-stowing. At the same time geotechnical problems have also been considered in the design process. The method consists of designing and developing a large dimension of solid coal block with a pair of chain pillars on both sides of the blocks. Coal can be safely extracted by slicing of the stooks on retreat. These stooks are of dimension 10m x 70m in the case of Chinakuri mine no. 1 (the deepest mine in India), because less than 10m width has been found inadequate from the stability point of view. The cut-out distance is recommended not to exceed 14m during splitting as well as slicing. The method has a potential to scale-up for higher coal production. To start with, this has been fixed at 700 tonnes per day (TPD), utilising the existing old coal evacuation and stowing arrangements, without any extra outlay on resources or infrastructure. This modified and innovative method, first of its kind, would expedite liquidation of about -72 Mt high-grade coal reserves.