Taconite EarthCache
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Taconite Harbor was developed in 2001 to provide a protected public access and Safe Harbor.
Taconite is a Precambrian sedimentary iron-bearing, high-silica, flint-like rock. In the late 19th and early 20th centuries, available iron ore was of such high quality that taconite was considered an uneconomic waste product. But shortly after World War II, most of the easily accessible high-grade ore in the United States had been mined out, and so mining companies turned to taconite as a new source of iron.
Thanks to Dr. E.W. Davis of the University of Minnesota, along with other scientists and engineers after years of laboratory tests and experiments an economical process was discovered to take the iron ore out of the taconite rock.
The Process
1. Blasting
Taconite is a very hard rock. Using explosives, the taconite is blasted into small pieces.
2. Transportation
Electric shovels scoop the taconite pieces up. Each shovel can hold up to 85 tons of rock! The shovels place the taconite into giant dump trucks. These trucks are as big as a house and hold up to 240 tons of taconite. The trucks take the taconite directly to the processing plant, if it is nearby, or to train cars if it is far away.
3. Crushing
At the processing plant, the taconite is crushed into very small pieces by rock crushing machines. The crushers keep crushing the rock until it is the size of a marble. The rock is mixed with water and ground in rotating mills until it is as fine as powder.
4. Separation
The iron ore is separated from the taconite using magnetism and then the powdered iron concentrate is combined with bentonite clay and limestone as a flux and rolled into pellets about one centimeter in diameter that are approximately 65% iron. The pellets are heated to very high temperatures to oxidize the magnetite (Fe3O4) to hematite (Fe2O3) for further processing. The remaining rock is waste material and is dumped into tailings basins.
5. Pellets
The concentrate (the wet taconite powder) is rolled with clay inside large rotating cylinders. The cylinders cause the powder to roll into marble-sized balls. (This is like rolling wet, sticky snow into balls to make a snowman). The balls are then dried and heated until they are white hot. The balls become hard as they cool. The finished product is a taconite pellet.
6. Ore Cars
Rail cars from the Iron Range bring the Taconic pellets to the loading facility. Each car can hold up to 70 to 80 tons of pellets.
7. Steel
The taconite pellets are loaded into ore ships. These ships sail on the Great Lakes to Gary, Indiana, Cleveland, Ohio and other steel-making towns. The taconite pellets are brought to the steel mills to be melted down into steel.
The Taconite Access/Safe Harbor, which was constructed in 2001, is located adjacent to the Cliff's Erie Taconite loading facility. Built in the mid-1950s, by the ore supplier Pickands-Mather, the company set out to build Lake Superior’s newest and most perfect ore loading facility.
Sources:
Ojakangas and Matsch, Minnesota’s Geology. 1982.
MN DNR webpage
www. Taconite.com
To claim credit for this earthcache- You must do the following:
1. At GZ there is a very large sample of taconite. What is the mass
(weight) of the sample according to the sign?
2. At GZ there is a ship anchor. The sign by it tells its mass (weight).
Using that number, calculate the number of tons of taconite used to
make the anchor. (1 ton of taconite produces 0.66 tons of steel)
Email your answers to the questions, to me, using the link in my profile only. If your answers are not recieved by me in an appropriate amount of time, your log will be deleted. Photos are accepted and appreciated as long as the answers to the questions are not revealed. You do not have to wait for confirmation from me before logging this cache as completed. Most of all……learn……and enjoy the view.
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