Aluminum Essay Research Paper Aluminum is one — страница 3

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such as sulfur and nitrogen oxides are released in the atmosphere refining and mining for aluminum. For all these reasons it makes sense to recycle. Today, recycling now accounts for about one-half of the total aluminum. Still much energy is wasted mining for aluminum, which could be significantly reduced if more aluminum were recycled. American consumers and industries alone throw away enough aluminum to rebuild the entire U.S. commercial air fleet every three months. (Aluminum Facts) Although it is so widely used, aluminum has only recently come into use. Unlike gold and silver, aluminum is never found uncombined in nature. It is always chemically combined with other elements. People had no way of separating aluminum from these elements until the 1800’s. (Walker, 31) A large

reason why aluminum is never found uncombined in nature is because it is so strongly attracted to oxygen. (Knapp, 4, 5) Aluminum is a reactive metal. When exposed to the air, it immediately develops an oxide coating that prevents further corrosion. However, along with a few other metals, aluminum compounds can be dissolved by both acids and alkalis. Metal compounds with this special property are called amphoteric metals. This property has been exploited in the aluminum industry as a way of dissolving aluminum compounds from bauxite while leaving the rest of the ore as a solid. This process is called the Bayer process. (Bowman, 392) Bauxite is a red rocklike material. It consists of aluminum oxide and a wide range of unwanted substances. To produce aluminum metal, the ore first

has to be concentrated, thus removing the bulk of the impurities. Then it goes to a refinery, where the pure metal is produced. The partly purified ore of bauxite, called alumina, is still a compound of aluminum and oxygen. To refine this aluminum, the alumina has to be dissolved and the aluminum recovered by electrical means. The process of using electricity to separate a metal from its rock ore is called electrolysis and takes place inside electrolysis cells. The alumina has to be liquified so that the aluminum compound will break apart into electrically charged ions. (Bowman, 394) Aluminum ions have a positive charge and can move through a solution to gather at the negatively charged electrode of the cell. Each cell uses a mere four to six volts. However, the current that

flows sometimes has as much as 150,000 amps. (Walker, 37) Aluminum is the most reactive metal in common use. All metals more reactive than aluminum (calcium, sodium, etc.) are unstable and need special handling. The reactivity of aluminum has advantages and disadvantages. One advantage is that it reacts with oxygen from the air, forming a gas tight and invisible oxide layer on its surface that protects the metal from environmental corrosion. On the other hand, being so reactive, the metal is very difficult to separate from its ore, and the costs of manufacture are high. (Geary, 185) Aluminum is of great benefit to the world. Hans Christian had no idea what his life changing discovery would contribute when he separated aluminum from its ore. Today an hour cannot pass that you do

not see the benefits aluminum brings to our everyday lives. From aluminum cans to electrical wires to computer chips, the tremendous contribution that aluminum has made is beyond calculation. Strong, lightweight, and relatively inexpensive, aluminum improves the quality of the lives of everyone. BIBLIOGRAPHY Advantages to Aluminum. http://www.kaiserextrusion.com/advantage.html. November 28, 2000. Aluminum Facts. http://www.epa.gov/seahome/housewaste/src/alum.htm. November,28 2000. Bowman, Kenneth A. World Book Encyclopedia. “Aluminum.” Chicago: World Book, Inc., 1992. Cobb, Cathy. Creations of Fire. New York: Plenum Press, 1995 Geary, Don. The Welder’s Bible. Pensilvania: Tab Books, 1993. Knapp PhD, Brian. Aluminum. Connecticut: Grolier, 1996. Newmark, Dr. Ann. Chemistry.

London: Dorling Kindersley, 1993. Walker, John R. Modern Metalworking. Illinois: The Goodheart-Willcox Company, Inc., 1985. Advantages to Aluminum. http://www.kaiserextrusion.com/advantage.html. November 28, 2000. Aluminum Facts. http://www.epa.gov/seahome/housewaste/src/alum.htm. November,28 2000. Bowman, Kenneth A. World Book Encyclopedia. “Aluminum.” Chicago: World Book, Inc., 1992. Cobb, Cathy. Creations of Fire. New York: Plenum Press, 1995 Geary, Don. The Welder’s Bible. Pensilvania: Tab Books, 1993. Knapp PhD, Brian. Aluminum. Connecticut: Grolier, 1996. Newmark, Dr. Ann. Chemistry. London: Dorling Kindersley, 1993. Walker, John R. Modern Metalworking. Illinois: The Goodheart-Willcox Company, Inc., 1985.