India is the third largest coal supplier in the world. The Indian mine operator „Sainik Mining and Allied Services Ltd.“, contractual partner of the country’s largest coal producer “Coal India”, operates a total of 21 Wirtgen surface miners. Ten 2200 SM are in operation in the 530 km² Gevra Mine in the province of Chhattisgarh. The local Wirtgen Group subsidiary’s excellent customer service has tradition: individually tailored service contracts use to guarantee security in planning and coal mining operation for several years already.
The vertical coal seams in the Gevra Mine require a selective mining method. Additionally, 90 % of the cut coal ought to have a maximum particle size of 100 mm. This is why, since 1999, the mine operators have gradually switched mining activities from drilling and blasting to Wirtgen surface mining. Presently, 80 % of the coal is already being mined using this environmentally friendly technique, another 20 % still via conventional methods. The mine operators are planning, however, to shift to 100 % surface mining of coal within the next two years (Fig. 1). In Gevra, surface mining has proven to be clean, safe and more environmental friendly as well.
In the mine, windrowing turned out to be the optimal mining method. Thanks to this technique, it is easier to check the material quality. Additionally, coal can be mined in the most economical way (Fig. 2). With windrowing, the cut coal is placed directly behind the machine, between the crawlers, without the use of a loading conveyor. This allows material to be cut independently of the loading process – although the coal has to be loaded separately via front loader later on. As a result, each 2200 SM – with a cutting width of 3.8 m and a cutting depth of 300 mm – can mine roughly 15 000 t of coal. The annual capacity of the coal mine is an enormous 80 million t, 90 % of which is being used as thermal coal for power generation in thermal power plants. Surface miners from Wirtgen are the ideal solution to mine the large deposit of over 10 billion t as efficiently as possible (Fig. 3).
The service contract especially tailored to the Gevra Mine guarantees that two Wirtgen engineers are available there all the time during operation. They provide support for all necessary maintenance activities relating to the surface mining fleet, including machine repairs, preventive maintenance measures, inspection of certain machine parts, training of machine operators, etc. The Wirtgen experts also make sure that all spare parts needed are being kept on stock.