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Sustainable Mining: Not an Oxymoron
Sustainable mining involves minimising impact on natural resources and habitat. Safe, scientific, efficient and environment friendly processes and advanced scientific mining technologies need to be adopted to ensure conservation of our natural resources. Sustainability initiatives that can be adopted by the mining sector include (a) mining of Lower seams containing high ash which gained to additional coal reserve and extended mine life (b) use of highwall mining technology which extracts locked coal left in barrier and batter after taking out coal from open pit mine otherwise it would have been lost forever, (c) Installation of state of the art beneficiation process to maximise recovery of coal to improve yield (d) beneficiation of carbonaceous shale (has carbon content of around 10 – 20%) (which is typically treated as waste and discarded) and other green initiatives like continuous reclamation, restoration and bio-diversity initiatives in mined area as per progressive mine closure plan which ensures maintaining ecological balance.
“High wall mining technology”: Leap in Sustainable Mining
High Wall Mining provides a unique solution to mine the coal blocked in barriers & batters which otherwise would have been lost, thus ensuring mineral conservation. This technology helps in extracting 30–35 % of the blocked coal. The technology is not only the most eco-friendly and safe method of coal extraction but also the most efficient method of natural resources utilization. It does not require any personnel to go underground, thus ensuring safety. The high wall miner machine stands on the pit floor or on a bench, directly in front of the exposed seam and makes long parallel rectangular drives into the coal seam. A remote-operated cutter is pushed into the seam by a string of push beams (unmanned coal-conveying elements) that transport the mined coal back to the entry of the drive onto a stockpile.
30-35% improvement over the earlier processes
By adopting high wall mining, Tata Steel will be able to extract 30–35% of locked up coal thereby achieving mineral conservation and clearing the path for scientific reclamation of area.
Following an opencast pit/mine operation, which is left abandoned or is totally reclaimed, a high wall/ultimate pit limit is created all along the mine boundary. Approximately 10 – 15% of the total coal resource is locked in barrier or batter along the mining lease boundary. This coal reserve is locked primarily because of a statute which requires the mining firm to leave a 7.5 m barrier pillar for the safety zone and to maintain a 450 slope angle. By adopting high wall mining, companies will be able to extract 30–35% of locked up coal, thereby achieving mineral conservation and clearing the path for scientific reclamation of area.
Potential areas of innovation
Some of the major challenges faced by the mining industry to undertake sustainability interventions include inadequate space for waste disposal and intermittent disturbance by the locals. The rehabilitation and resettlement of displaced people is quite challenging. The socio-economic condition of the community in and around mining area adds to the issue.
Mine mechanisation should be favoured for maximum extraction and monitoring.
Going forward, more mine mechanisation should be favoured for maximum extraction and monitoring. Coal recovery can be maximized though state of the art beneficiation technology. Focus must be given to waste utilization. The government approval systems can be improved by adoption of IT.
The article has been contributed by Mr. Sanjay Rajoria, General Manager, Tata Steel West Bokaro. He has been instrumental in Tata Steel bagging the Deming Grant Prize, the Jharkhand Pollution Control Board Award for the Rain Harvesting Projects & Mines Safety Awards.