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Breaking bottlenecks at the face with continuous haulage.
Min Eng 1979 Jul; 31(7):788, 790-792, 795
Introduction of continuous mining machines in the late 1940s created a new production bottleneck in room-and-pillar sections - the shuttle car. While continuous miners could cut and load coal at a nearly constant rate, the mining sequence was repeatedly interrupted as fully loaded shuttle cars changed place with empty ones. This wait-for-the-shuttle delay period forced the coal industry to reassess the shuttle's batch-type procedure with an eye toward continuous haulage systems that would allow uninterrupted coal flow from face to portal. In 1976 a total of 7666 shuttle cars transported most of the 168 million tons (186 million st) of coal cut by 2366 continuous mining machines. Only 5.1% or 8.6 million tons (9.5 million st), of this coal was transported from the miner to outby haulage via a continuous haulage system. Recent studies have shown that nearly 25% of the continuous miner cycle time is consumed by delays in the haulage system, usually waiting for shuttle cars. Computer simulations of a face operation indicate that up to a 45% increase in coal production may be realized with a continuous haulage system, assuming that the outby haulage system can handle this increased tonnage. Coincidentally, some mines using continuous face haulage claim a 50% production increase over shuttle car haulage. One mine operator has reported section productivity of up to 91 tons (100 st) per face per man via continuous haulage. These documented production records and computer simulations, along with common sense, indicate the potential of continuous face haulage in room-and-pillar coal mining. The late 1960s and early 1970s saw several mining machinery manufacturers introduce mobile bridge carrier/piggyback bridge conveyor types of continuous haulage systems for underground coal mines. These systems have shown limited potential in some operations and outstanding success in others. Since it appears that no one type of system is universally applicable to all underground mining conditions, the US Bureau of Mines in 1975 began a long term effort to investigate continuous haulage concepts that would provide operating alternatives in various coal mining conditions. Following creation of the Department of Energy, this program work was transferred from the Bureau to DOE in October 1977. Besides the large R&D effort devoted to hydraulic pipeline transport of coal underground, DOE has funded numerous other continuous haulage projects in both room-and-pillar and shortwall mining plans. This article will focus on those developments that are most topical or have progressed to a hardware stage.
Longwall-mining; Room-and-pillar-mining; Underground-mining; Coal-mining; Mining-industry; Mining-equipment
OP; Journal Article
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Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division