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Giant Dragline Excavators from the 1960s

The sizes of today’s dragline excavators are much smaller compared to more than 40 years ago. Larger draglines such as the Bucyrus Model 4250W and Marion 7900 turned the 1960s into the era of super dredgers. The mining industry has valued the benefit of the extremely low waste disposal cost of these machines over their high capital cost.

The scant information on Utah International’s Marion 7900 is available to the public. The largest among the former Utah Mining and Construction Company’s dragline sizes had a boom length of 275 feet (83.8 meters) and a bucket capacity of 40 cubic yards (30.6 cubic meters). . It excavated 7000 tons of coal per day. The large dragline unit was disassembled for a major inspection in 2005. Repairs and upgrades in Morocco brought the machine back to work smoothly with smaller dragline excavators.

The CEMEX operation outside of Pittsburg, Pennsylvania, purchased a 2,000-ton trawl dredger. The Marion 7820-M, nicknamed ‘Brutus’, discovered the limestone needed to make cement. It has a 305-foot long boom and a 289-foot working radius. The bucket can carry 45 cubic yards of materials and can dig up to 170 feet. The 4,000,000 pound weight was somewhat common for dragline excavator sizes of the time. It was originally made for Pyramid Coal Company’s Rockport surface mine in Rockport, Kentucky in the 1980s.

Another large unit is the 4250W dredger unit from Central Ohio Coal Company (a division of American Electric Power). He was popularly known as the ‘Big Muskie’. It took three years for mining equipment manufacturer Bucyrus International, Incorporated to build the machine that made other sizes of dragline excavators appear less powerful. The 27 million pound (12 million kilograms or 12,000 metric tons) earthmoving machine operated in Muskingum County, Ohio, from 1969 to 1991. The only dredge of its size ever built extends to 487 feet, 6 inches (149 m.) with the arm down. Its width of 151 feet 6 inches (46 m.) Needs an eight-lane highway to run; While its height of 68 m. (222 feet 6 inches) will be more than enough to look down the roof of a 22-story building. The machine was later scrapped in 1999 after demand for Ohio’s high-sulfur coal plummeted in 1991. The 165-cubic-meter (220-cubic-yard) bucket weighing 230 tons is preserved as a monument to the miners from southeastern Ohio.

Today, construction and mining equipment manufacturers have considered the risks of building large dragline excavators. The new models, although much smaller in size, can be used for both civil engineering projects such as infrastructure construction and open pit mining operations, such as moving overburden above coal and tar sand mining.

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