Today’s dragline excavator sizes are much smaller compared to more than 40 years ago. Larger draglines like the Bucyrus model 4250W and Marion 7900 turned the 1960s into the era of super draglines. The mining industry has valued the benefit of the extremely low waste disposal cost of these machines over their high cost of capital.
Little information is available to the public about the Utah International Marion 7900. The largest among the former Utah Construction and Mining Company dragline excavator sizes had a boom length of 275 feet (83.8 meters) and a bucket capacity of 40 cubic yards (30.6 cubic meters). He was digging 7,000 tons of coal per day. The large dragline unit was dismantled for a major inspection in 2005. Repairs and upgrades in Morocco allowed the machine to get back up and running with smaller dragline excavators.
CEMEX’s operation outside of Pittsburgh, Pennsylvania, purchased a 2,000-ton traveling-type dragline. The Marion 7820-M, nicknamed ‘Brutus’, discovered the limestone needed to make cement. She has a boom length of 305 feet and a working radius of 289 feet. The bucket can carry 45 cubic yards of material and can dig up to 170 feet. The 4,000,000 pound weight was somewhat common for dragline excavator sizes of the day. It was originally manufactured for the Pyramid Coal Company’s Rockport Surface mine in Rockport, Kentucky in the 1980s.
Another large unit is the Central Ohio Coal Company’s (a division of American Electric Power) 4250W dragline unit. He was popularly known as the ‘Big Muskie’. Mining equipment manufacturer Bucyrus International, Incorporated took three years to build the machine that made other sizes of dragline excavators seem less powerful. The 27 million pound (12 million kilograms or 12,000 tons or 13,000 metric tons) earth-moving machine operated in Muskingum County, Ohio, from 1969 to 1991. The only dragline of its size ever built spans at 487 feet, 6 inches (149 m.) with the boom lowered. Its width of 151 feet 6 inches (46 m) necessitates an eight-lane highway to travel on; while its height of 222 feet and 6 inches (68 m.) will be more than enough to look down from the roof of a 22-story building. The machine was later scrapped in 1999 after demand for high-sulfur Ohio coal plummeted in 1991. The 220-cubic-yard (165-cubic-yard) bucket weighing 230 tons is preserved as a memorial to the miners of southeastern Ohio.
Currently, construction and mining equipment manufacturers have considered the risks of building large excavators. The new models, although much smaller in size, can be used for civil engineering projects as well as infrastructure construction and open pit mining operations, such as moving tailings above coal and oil sand extraction.