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)
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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 scattered 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 extremely 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 collapsed 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.