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COPPER MINING IN INDIA

    The copper ore production is wholly under the control of the public sector companies-M/s Hindustan Copper Limite, M/s Sikkim Minning Corporation (SMC) and M/s Hutti Gold Mines Ltd. In Rajasthan, four mines are operated by M/s Hindustan Copper Ltd. whereas Dikchu mine is operated by SMC and Ingeldhal mine is operated by M/s Hutti Gold Mines Ltd. The rich deposits of copper ore are confind to the three regions-Khetri copper belt in Rajasthan, Singhbhum copper belt in Bihar and Malanjkhand copper belt in Madhya Pradesh. Mining of copper ore in Rajasthan and Madhya Pradesh is controlled by M/s Hindustan Copper Ltd. whereas mining operation in Singhbhum belt is controlled by M/s Indian Copper Complex.

    Mining is carried out by opencast as well as by underground method. The Malanjkhand copper mine and the Chandmani copper mines are operating by opencast method. The main underground mines are Khetri, Kolihan, Dariba, Rakha and Dikchu mines. Underground mines operate mainly by board-and-pillar method where the orebody is flat. Wedge and pyramid cut are used for drilling and getting 1.5 m pull blast, i.e., 65 per cent of the drilling depth.

    Stoping methods are also used in underground mines. Electric LHD’s operated stopes resulting the Increase of output per man shift from 1.5 to 5 tonnes. The Khetri copper mines introduced faster tunneling with drill jumbos and Eimco loaders. Trackless loaders dump the ore/waste into granby cars which are subsequently pulled by locomotives. In underground stoping, Vertical Crater Retreat (VCR) method is also used for bulk mining technique which is based on the concept of spherical charging and blasting. Blasting long and large diameter holes gives a vertical retreat of the stope-back and making operations are undertaken by the help of remote-controlled LHD’s

    Stoping with large diameter blast holes is being practised at present. Diameter of these holes are 162 mm and drilling is done with level intervals of over 60 m. Some mines have gone to a depth beyond 1 km from the surface and geothermic gradient is high. In these mines, drop raising techniques are used. In drop raising technique, holes can be drilled to 100 m in length and 165 mm in diameter.

    In case of flatly dipping orebodies, breast stoping, room-and-pillar and post-pillar stoping methods are used. For production of copper concentrates, HCL has installed capacity of 5.578 million tonnes of copper ore which is likely to increase due to expansion of Khetri smelter and malanjkhand mines.