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Govt’s underground coal mining plan hits hurdles

The government is considering a push for underground mining, a method to extract deep-seated coal, in a bid to boost coal production but is facing challenges of resources and lack of machinery.
“There’s a definite thrust towards it. We are trying to understand it,” coal secretary Anil Swarup said in an interview on Wednesday.
India has set itself an ambitious target of increasing coal production from 565.77 million tonnes in 2013-14 to 1.5 billion tonnes by 2020 to reduce dependence on imports.
The most prevalent method of coal mining in India is opencast or surface mining, used for extracting coal deposits at shallow depths. It’s a more efficient process than underground mining, the latter needing high technical expertise and greater investments.
The share of underground coal mining in India country has slumped from 16.3% to 8.8% in the last decade.
“The primary reason is the rise in production from opencast mines, which is increasing at a greater rate than underground mines. Some potential underground mines have also been converted to opencast mines,” said S.K. Dubey, technical secretary at the Central Mine Planning and Design Institute, the consulting arm of the world’s largest coal mining company, Coal India Ltd (CIL).
The most efficient way to carry out underground mining is to extract long panels of coal with the use of massive shearers and a roof support system through longwall mining. A typical longwall machine moves along the coalface cutting coal slices while the roof is allowed to collapse.
This mining technique hasn’t been successful in India because, Dubey said, “We don’t have large areas of continuous coal deposits underground. This makes estimation and implementation of mining very difficult. We had very ambitious projects in 1970s and 1980s, which were unsuccessful due to these conditions. In China or the US, large deposition of coal seam is available free from any geo-mining disturbance, which makes longwall mining feasible.”
In India, Singareni Collieries Company Ltd (SCCL) has the highest share of underground mining production among public sector coal mining companies. According to an SCCL official, the company has been sourcing the machinery required for longwall mining from Caterpillar Inc., a US-based company, since last year.
“Technology needs to be upgraded. For longwall mining, our plan for the future is to get mines enlarged by merging two mines or opening a new large mine where longwall mining is possible,” said Swarup.
One of the ways that can boost underground mining is through a piece of equipment called a continuous miner. It requires less investment and can work in difficult conditions, even in the absence of a long stretch of continuous deposition. “Continuous miners have already been deployed at many mines and it has shown great potential,” said Dubey.
Productivity in a mine is measured through output (in tonnes) per man-shift (OMS). The OMS for underground mines of CIL in 2013-14 was 0.76. The corresponding figure for opencast mines was 12.31. “There are restrictions in underground mining. Coal can only be extracted by haulage or conveyor belts. It has to travel a long distance and therefore the efficiency is low,” said the SCCL official.
There is, however, one important factor which strengthens the case for underground mining. The use of explosives in opencast mining affects the vegetation, soil and wildlife around the mine. “Environmentally, underground mining is much better than opencast because it doesn’t immediately affect the natural habitat,” said Swarup.
“Hopefully the proportion (of underground mining) would go up a bit in the sense of our understanding of new technology and opening of larger mines where new technology could be deployed,” said Swarup.

source: http://www.livemint.com