Mining 101. When harvesting from the earth solid fuel like coal, surface mining is preferred to subsurface, for both cost and safety reasons. Surface mining falls into two types; open pit, and strip mining. Open pit is used when the target fuel, mineral, or ore spreads over a wide area that runs deep. Everything other than the target substance (called “overburden”) is scraped away, the ore is blasted apart with explosive, and the chunks are carted away by large trucks. As the miners go deeper, they also widen out the working area. A worked-out open pit mine usually looks like a large bowl with ledges running around the inside edge of the mine.
Now, those of you, dear readers, who are younger than forty or so will be aghast at the thought of open pit and strip mining; those of us who are older understand that before the study of environmental impact had matured – before, even, its infancy, when people first became aware that everything we do affects the world around us – this was the way mining was done. Nowadays, if open pit mining is the best way to get at a mineral, care is taken to reduce that impact and the area is reclaimed afterwards using the guidelines of the Surface Mining Control and Reclamation Act of 1977.
So. As the nation was becoming more industrialized and people were desiring more and more the conveniences of electricity along with machines to wash laundry and preserve fresh food with more sustainability and less mess than an icebox, the demand for coal went up; when the demand for coal increased, coal mining companies had to come up with ways to meet it. One of the most typical ways to meet increasing demand was to increase the size and capacity of the machines mining the coal. (And if you’re too young to know what an icebox is, check it out here.)
Enter the dragline excavator.
Big Muskie was the largest walking dragline excavator ever built, and operated in Ohio from 1969 to 1991. During that time, she moved 608,000,000 cubic yards (in cubic meters, 465,000,000) of overburden in mining Ohio brown coal. (Just for comparison, that’s twice the amount of earth moved during the construction of the Panama Canal!) Big Muskie did that with a bucket large enough to fit two Greyhound buses standing side by side. She was powered by electricity (13,800 volts of it!) because deisel generators just couldn’t provide enough juice to run this baby. The electric trailing cable had its own transporter to move it when Big Muskie was moving (at a whopping 1.76 inches per second, and only over a carefully graded and smoothed travelway that had to be prepared to keep Big Muskie from sinking into the soil and getting stuck – or worse, tipping over). The Central Ohio Coal Company had special agreements with the local power companies to take that extra load and though Big Muskie’s crew of 5 ran the machine around the clock, emphasis was placed on night work because the per-kilowatt hour charge was cheaper. While working, Big Muskie burned through enough electricity to power 27,500 homes.
It’s sad, that such a marvel of engineering has such an ending to her story, though. Out of service since 1991 because of changing times and methods, in 1999 the final decision was made to break her down and sell her parts for scrap. The bucket alone remains as a testament to this “World’s Largest.”