Coal Age Magazine - For nearly 100 years, Coal Age has been the magazine that readers can trust for guidance and insight on this important industry.
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1980-1989 built with 60-yd dippers. Hydraulic exca- vators are becoming more prevalent. By 1987, the Dresser 301-M, a new electric shovel, can load 170-ton trucks. It is avail- able with a 65-yd dipper. Still other types of machines have been developed that employ the continuous cutting concept. Most of these have a transverse cutting drum, usually under the machine, that can cut and load coal within inches of the bottom and then top load it into haulers. Examples include the Easi- Miner, distributed by Bucyrus-Erie, and the surface miner manufactured by the German firm, Wirtgen GmbH. In a one-section mine, Leckie works two production shifts daily and assigns a full crew to maintenance and clean up on the third shift. The ratio of maintenance to production may seem high, but the productivity speaks for the efficien- cy of the operations. *Coal Age, September 1984 Diesel-powered equipment slowly but surely gains a foothold in America's underground coal mines. Long rejected by the UMWA and still illegal in West Virginia, diesel haulage and supply vehi- cles nevertheless have proven themselves sufficiently productive for mine operators to bring them into the mines in greater numbers. Thin-seam mines in the East are using continuous haulage systems. A 10-miner crew using a continuous haulage system at GM&W; Coal Co.'s Grove No. 3 mine in Pennsylvania sets a company record by mining 1,793 tons of raw coal in one shift in a region where 800 tons per shift is considered good. The crew was using a Long-Airdox continuous haulage system and a Lee Norse HH106 continuous min- er advanced 210 ft in 11.5 cuts in 8-ft coal. In 1980, longwall production account- ed for approximately 5% of the coal mined in the U.S. The first U.S. Longwall Census appears in the December 1980 edition. By mid-1985, the number of longwalls climbs to 118 faces, of which nearly 110 were equipped with shield roof supports. Longwall mining continues to advance. Westmoreland Coal's Holton mine in Virginia programs the shearer to initiate shield movement as it travels along the face. In 1986, Joy and Dowty report that Mapco's (now Alliance Resource Partners) Mettiki mine in Maryland has set a long- wall production of 322,403 tons in 22 days. 140 www.coalage.com "Consol's underground productivity increased 75%, compared with 60% increase for the coal industry," Ralph Bailey, chairman of Conoco, the sub- sidiary through which Consolidation Coal Co. reports to du Pont. By the end of the decade, continuous miner sections are routinely reporting cut rates of more than 1,000 tons per shift. Surface Mining Scales Up The coal industry purchased and assem- bled a lot of draglines during the 1970s. In the 1980s, some of those surface mines encountered higher overburden and dragline re-handling was becoming an issue. Surface mines began using truck- shovel mining in pre-benching applica- tions, while lignite mines with soft, sandy overburdens were successfully using BWEs and cross-pit spreaders. In September 1986, Arch Minerals installed a BWE at the Captain mine in Illinois. The 700-ft machine was built on the revolving frame of an older BE stripping shovel. It works in tandem with the Marion 6360 supper shovel. Texas Utilities installed a massive cross-pit spreading system that became operational in 1986. Spanning 1,000 ft, the huge XPS system strips 4,000 cu yd per hour of overburden to access Texas lignite. The unit was built by Mannesmann Demag Corp. in Germany. Most electric shovels have a 40-yd dip- per capacity or less, but some have been 100th Anniversary Special Issue Caterpillar Tractor Co., which was marketing the D11N dozer, became Caterpillar. The size and strength of doz- ers increase. Ripping mechanisms for doz- ers also improved. Hydraulic systems that impart a series of impulses to the dozer's ripper shank to make it function some- what like a jack hammer were developed and thus enhanging the dozer's ability to fracture rock. The size of the rolling stock continued to grow throughout the 1980s. A front-end loader survey in 1980 included names such as Caterpillar, Clark (Michigan), Dart, International and Marathon LeTourneau. Bucket capacities on the mining class load- ers ranged from a 12.5-yd Cat 992C to a 24- yd Clark 675. Marathon LeTourneau had the 22-yd buckets for the L-800 and L-1200. A report on haul trucks in the early 1980s lists, among others, the 100-ton Cat 777, 170-ton Euclid R-170E, a 3,500-hp, 350-ton Terex Titan (the caption explained it could haul uphill), a 200-ton Mark 200, a 200-ton Rimpull CW 200, and a 250-ton Wabco 3200 (2,475 hp). Blasting crews at the mines begin honing their skills. Mixtures of ANFO and emulsions of ANFO take the place of dynamite. In addition to improvements in blasting agents, the use of sequential blasting gained in popularity. Such blast- ing, timed to go off sequentially millisec- onds apart, was used for casting over- burden into the previous pit and on to spoil piles, as well as to improve frag- mentation. Drilling equipment also took advan- tage of new technology. To improve blast- hole drilling, drills acquire on-board control systems that consist of a micro- processor-based drill monitor that auto- matically zeros each new hole, provides the drill operator with a display of the depth and rate of penetration, prints an August 2012