Coal Age

AUG 2012

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1990-1999 research organizations are developing electronic delay detonators. Mine plans are adapting to electric shovels loading 240-ton haul truck in three passes. By 1990, Dresser's Haulpak Division is marketing a 240-ton 830E electric drive haul truck. Harnischfeger is promoting the P&H; 4100 electric shovel, which can load a 240-ton haul truck in three passes with a 56-yd dipper in 28 seconds. In the mid-1980s, nearly all haul trucks greater than 120 tons were diesel- electric powered. When Cat announced the 240-ton 793 haul truck in 1991, the industry realized that the mechanical drive transmission had caught the elec- tric drives. Haul truck makers include: Cat, Dart (Unit Rig), Euclid (VME), Haulpak Dresser, Komatsu Dresser, Lectra Haul (Unit Rig), Titan (Marathon LeTourneau) and Wiseda. Just as the industry starts to grow comfortable with three-pass loading, truck makers begin to move toward today's ultra-class haul trucks. During June 1995, Unit Rig introduced the new 260-ton MT-4400 Lectra Haul. Its frame can support a 310-ton load without fail- ure and will provide a basis for still larger trucks in the future. Komatsu Dresser introduced the 300-ton 930E haul truck. Electric shovels are now four-pass loading 320-ton trucks. In the past, haul trucks chased the shovel and now the shovels were chasing the trucks. In addi- tion to improving the capacity, shovel makers were looking to improve reliabili- ty with better electronic switching tech- nology. They are also improving the diagnostics system to better trou- bleshoot maintenance. The man- machine interface continues to improve. Hydraulic excavators have grown to the point where they can also load 320- ton trucks. At this point, almost all of the hydraulic excavators are paired with a truck manufacturer—Komatsu now owns Demag, Terex Ming combines O&K; and Unit Rig, Hitachi is paired with Euclid, and Cat and Liebherr make hydraulic excavators and trucks (Liebherr pur- chased Wiseda). Hydraulic excavators offer a great deal of versatility. Although they are diesel-powered, many of them employ a similar electronic monitoring system and improved operator interface. In July 1998, Komatsu Demag unveiled the H655S hydraulic mining shovel with a 46-yd bucket. The machine weighs 1.51 million lb and is powered by a 3,714-hp 16-cylinder diesel engine. New geometry increases the shovels breakout capacity. Michelin develops the 63-inch tire, which allowed truck makers to move to the 360-ton level. Liebherr introduced the 360-ton T282 during October 1998. Cat announced it will build the 360-ton 797 by the end of 1998, and predicts its mechani- cal drive will deliver 5% to 10% better fuel costs per ton as well as 10% to 15% lower operating costs. With the exception of Cat, all of the trucks are using AC drive systems. Cat, however, stands by mechanical drive sys- tems and says its trucks are operating 500 to 1,000 hours more than the electric drives. Electronic monitoring and con- trol systems have become standard items on the tucks as well as machine health diagnostics. Black Thunder, one of the first Powder River Basin mines to test and adopt Wiseda's 240-ton hauler (shown above), now owns 11 of them. *COAL, July 1993 The haul trucks are getting larger and so are the loading height and tray width. In August 1999, P&H; launched the 4100 XPB electric shovel to keep pace with ultra-class haul trucks. Changes to the front-end geometry enable the 4100 XPB to attain the increase dumping height required for the new trucks. It also results in a higher suspended load rating and in quicker dipper loading. Coal Preparation Advances An article in the 1994 edition of COAL talks about "The Prep Plant of Tomorrow" detailing two DoE-funded processes that reached the commercial stage. The air-sparged hydrocyclone exploits surface property differences in a cyclonic flow field to rapidly separate coal from mineral matter. Research on the Microcel column flotation cell under- scores the importance of employing a wash water spray positioned in the froth zone. Cat predicts its 360-ton-capacity 797 mining truck will deliver 5% to 10% better fuel cost per ton, as well as 10% to 15% lower overall operating cost per ton. *Coal Age, April 1999 168 www.coalage.com 100th Anniversary Special Issue By the mid-1990s, more than one-half of the prep plants in the U.S. operate a August 2012

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