My trip to the Powder River Basin of Wyoming offered
me the opportunity to view 2 of my favorite things-Draglines and Trains.
The Powder River Basin of Northeastern Wyoming
supplies 80% of all the coal burned in US electrical power generation
plants. In 2000 the 6 largest strip mines in Campbell County
Wyoming shipped over 300 million tons of low sulfur coal.
The coal mining process is as follows: First CAT
D11 dozers (the world's largest) strip off the top soil and it is
truck to a storage area for reuse in reclaiming the land after the
coal has been mined. Next, Large Draglines (so called because a
line drags a large scoop called a bucket along the ground towards the
dragline until it is full) strip off all the ground needed to expose
the coal (this ground is called the overburden). To assist the
draglines and make the job easier, the overburden is first blasted
with dynamite. Large Bucyrus-Erie drills are used to drill the
holes for the dynamite. The blast is designed to throw as much
of the overburden as possible into the pit next door where the coal
has already been mined. This blast also then starts the
reclamation project on that mined area.
Once the coal seam is exposed, large electric
shovels like the P&H 4100 dig out the coal and load into onto the
world's biggest trucks. These trucks then haul the coal to a
dump bin and dump it into a coal crusher to create smaller
chunks. Then the coal is taken via conveyor belts to large coal
This coal is shipped in 110-120 car trains made up of
80-110 ton capacity rotary dump gondolas. These gondolas are
filled via automated loading facilities where the unit train moves
through the coal storage silo at a steady page of 1 mile per hour and
the cars are uniformly filled and weighed as they move. It
takes about 2 hours to fill a train.
The largest Power River Basin mine complex in terms of
2000 shipment volume is the Arch coal complex consisting of the Black
Thunder and Jacobs Ranch mines. In 2000 they shipped more than
60 million tons of coal. Since the average unit train holds
12,000 tons, that means they shipped an average of over 13
trains per day every day 365 days per year. Both Union Pacific
and Burlington Northern-SantaFe serve these mines. Together these
railroads have invested over $3 billion in track, engines and hopper
cars but Powder River Coal is their single largest source of revenue.
As a railroad "nut" I was very impressed with all the
railroad action around these mines.
The average overburden (dirt on top of the coal)
ranges from 50 to 170 feet thick and the coal seam ranges from 30 to
over 100 feet thick. It is estimated that at current
consumption rates there is a 190 year supply in the Powder River Basin.
It takes a well organized and well run mining
operation to mine that much coal. Arch Coal Company uses
a large amount of equipment to operate these mines. This
includes 4 draglines, a Bucyrus-Erie 2750WS, a Marion 8750, a
B-E1570W and a B-E 1300W. They also have 6 large shovels
(Marion 351 and P&H 4100), 4 B-E Drills and over 20 large trucks
(ranging in size from a Komatsu 360 ton capacity to a Haulpak 240 ton
capacity machine). They are also bringing in a number of new
CAT 797 250 ton capacity trucks.
I have attached some of the photos I took on my
trip to show these "monster machines" in action and
help tell the story of how these mines work.