POWDER RIVER COAL COMPANY
GILLETTE, WYOMING


Equipment and Mining Glossary

BTU--British Thermal Unit. Standard for measuring the energy required to raise the temperature of one pound of water one degree Fahrenheit.

COAL SEAM--An underground layer of coal.

COMPUTERS--Technology found in all areas of coal mines including trucks, shovels,
draglines, warehouse, load out, lab, shop, and offices.

CONVEYOR BELT--A moving covered belt that carries the coal to the silos.

CRUSHER--An area in the hopper where the coal is crushed or broken into pieces approximately
2 3/4" to 3" in size.

DRAG LINE--This earth-moving machine rotates 90 degrees as it excavates the overburden. Two operators are needed to run this equipment. One operates the dragline while the other checks the oil and keeps the gears clean.

DRILL--This machine drills holes into the overburden or coal so that blasting materials
may be inserted. Blasting loosens the overburden or coal so that the shovel is able to load the material into the haul trucks.

ELECTRIC SHOVEL--This earth-moving equipment excavates overburden and coal after it has been loosened by blasting and then places the material into the haul trucks. Cables, like giant extension cords, carry electricity from mine sub-stations to the shovels to operate them. The shovels require 7,200 volts of electricity. (As a comparison, 120 volts are needed to operate a toaster).

EXPLOSIVES-- A mixture of fertilizer and diesel fuel used to break up the overburden and coal during blasting.

GRIZZLY FEEDER--An area in the hopper that feeds or places the coal into the crusher.

HAUL TRUCKS--These trucks haul coal and/or overburden to the proper destination. The average speed is 35 miles per hour. Haul trucks have computers on board that keep track of the load weight and any errors (oil pressure,etc.), as well as the speed that the truck is traveling. Load capacities of haul trucks is anywhere between 190 to 270 tons.

HOPPER--The area where haul trucks dump the coal. The hopper works on a traffic light system, red--do not dump, yellow--prepare to dump, green--dump.

LAB--The area of the mine where the coal is analyzed. Here they check the Btu's, sulfur, moisture, ash, and sodium content.

LOAD OUT--Where the coal is actually loaded into the trains.

OVERBURDEN--The dirt that covers the coal. It is removed and used to fill areas that have already been mined, or it is stock-piled for later use.

PIT--The area of the mine where the coal is actually excavated from the ground.

PREPARATION PLANT--The area of the mine where the coal is prepared for the customers as well as loaded onto the trains.

SCRAPERS--Scrapers are graders used to maintain the haul roads, as well as keeping the coal accessible to the electric shovel.

SHOP--The area of the mine where the equipment is repaired and maintained.

SILOS--Round buildings that store the coal until the trains arrive for loading.

WATER TRUCKS--Trucks that hold approximately 18,000 gallons of water. The water is used to wet down the roads to prevent excess dust. There are state and federal laws that regulate the amount of dust particles emitted into the air.

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