Iron in its pure state is soft, malleable and ductile (that can be stretched, drawn or
hammered thin without breaking ((Webster's Dictionary, 419, 1988)) with a hardness of
4-5. It is easily magnetized at room temperatures and this property disappears when
heated above 790 degrees Celsius.. Metal iron occurs in a free state in only a few
localities, notably Greenland (Encarta, 1996). One of the physical properties of iron as
an ore is its color which can be black, brown or even reddish. Hematite is the most
important iron ore, commonly occurs as "kidney ore" - so -called because of its shape
(Symes, 1988, 56). Other ores included goethite, magnetite, siderite, and bog iron
(Encarta, 1996). Even though iron is tough and hard it is still easy to work. Iron is a
active metal and will combine with halogens, carbon, etc. It has an atomic weight
55.847, it's atomic number is 26, it's specific gravity is 7.86, it's melting point is
1535 degrees Celsius, and it's boiling point is 3000 degrees Celsius. It burns in oxygen
forming ferrous oxide. When exposed to moist air, iron becomes corroded, forming a
reddish - brown, flaky, hydrated ferric oxide, commonly known as rust. (Encarta, 1996)
Iron is formed in shallow seas. It comes out of the water and collects on the sea
floor. This creates an underwater deposit. This process occurs over billions of years.
Through plate movement the whole sea floor is eventually moved up out of the water. Once
out of the water, the iron has formed a land deposit. The biggest iron deposit in the
United States is in the Great Lakes. Northern Minnesota is often called the Iron Range.
There are two ways iron deposits are located. In the first method special machines that
detects the iron's magnetism are used ti find a deposit. In the second method a plane
with special equipment flies over an area of land suspected of having ore deposits and
shoots down sound waves to determine if that area contains iron deposit. The waves come
back up to the plane and determined by the pattern one can tell if there is an iron
deposit.
In the early 1990's annual production of iron ore in the United State exceeded 56
million metric tons (Encarta, 1996). There are two ways in which iron is mined. The two
ways are open pit and shaft mining. Open pit mining is used 85% of the time for shallow
deposits. Open pit mining is also call strip mining. The way open pit mining works is
the top soil is removed with a bulldozer and the land is terraced downward. Then the
miners set off a large blast which scattereds and loosens the ores. Truckloads of ore
are carried to the surface. As the pit gets deeper and deeper the expense increase and
at some point it is more economical to go to the second method of mining. The second
method in which iron is mined is called shaft mining. Shaft mining is usually used for
deep and concentrated iron deposits. The way shaft mining works is that a large machine
crushes the rock and then conveyor belts are used to transport it up to the surface.
The definition of refining is to make fine or pure; free from impurities; dross,
alloys, sediment, etc. When they refine iron they alloy it with other metals. This
produces a very common metal known as steel. Steel is very widely used. It is used from
making buildings to making single screws. Though one might think because steel is made
from refined iron the properties would be similar. This is false. It is the same as
gasoline is refined oil. One might think they are pretty similar but they are very
different.
Mining is considered to be extremely detrimental to the environment. Open pit mining
has left a major effect on the surrounding environment. Large areas of land are
literally dug up and large creators are left. The huge holes disrupt the environment and
aren't aesthetic. However, some pits, such as those on the Mesabi Range in Minnesota
have been turned into lakes and this has created recreational areas for people as well as
habitats for birds, fish and other wild life. The noise of the large machines and the
frequent blasts in mining must scare away much of the animal life. Fumes from dynamite
explosions produce extemely poisonous gases and in mining pockets of hazardous materials
may be released. Dust produced during mining can cause illness, especially lung disease;
black lung disease is associated primarily with coal mining. In shaft mining, gas can
accumulate and explosions can results. Shafts have also collasped killing workers.
Refining of the ore causes dust and fumes to be released into the environment. In the
smelting process to make steel, acidic clouds are formed from the burning of coal. In
the U.S., scrubbers are required in smoke stacks to prevent acid rain. Through the
years, iron and steel have been used to build our country and provide employment. It's
hard to imagine what life would be like if man had not learned how to mine and
manufacture iron. Mining is now done in a manner to conform more to the environment.
Once the iron ore is mined it is taken to a refinery and purified. Much of the iron
from the Northern Minnesota ranges are loaded on barges at Duluth and shipped via the
Great Lakes to port near Pennsylvania, such as Erie and then shipped to cities such as
Pittsburgh and Bethlehem. Shipping it here is easier than to ship the coal to make steel
as more coal is used than iron in this process. Pure iron has very limited use. It is
used to produce galvanized sheet metal and electromagnets. Most of the iron used
commercially contains small amounts of carbon and other impurities. This includes
wrought iron, cast iron and steel. Smelting was used to produce early forms of these.
Today blast furnaces that use blasts of air heat the iron with ferroalloys to produce
steel. (Encarta, 1996). The steel is then shaped into screws which are used to hold the
face mask on the shell of the football helmet. Steel is used for this purpose due to its
strength. The physical properties of iron are totally changed once it has become steel
and therefore good to make screws as it will no longer rust.
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