Aluminum Essay, Research Paper
Dear Xavier,
Hello buddy! How is the weather in Paris? It is extremely cold in New York and there is snow all over the place. The reason I am writing is to give you the information you wanted on aluminum. I have everything you would possibly want to know about everything from mining to recycling, but I will begin with a little background on the element first.
Aluminum is the third most abundant element in the Earth’s crust and was probably formed during the birth of our solar system through collisions of hydrogen atoms under intense heat and pressure. Aluminum never occurs as a metal in nature and is only found in the form of its compounds, such as alumina, because of its strong affinity with oxygen. It is this special bond for oxygen that explains why it withstood all attempts to prepare it in its elemental form until well into the nineteenth century.
The aluminum industry was founded in 1854, but it was not until the late 1880’s that a method was found to bring down the prices and permit aluminum to be used in a wide variety of ways. Most of the aluminum in the world today is made from Bauxite. It was first discovered in 1821 near Les Baux, France. It was formed by the weathering of aluminous rocks such as feldspar, nepheline, and clays. During the weathering, these rocks are decomposed and leached out, leaving behind a residue of ore rich in alumina, iron oxide, and silica.
Most of these large Bauxite deposits are found in the tropical and the subtropical climates, where heavy rainfall, warm temperatures, and good drainage combine to encourage the weathering process.
Because Bauxite is usually found near the surface, it is mined by open-pit methods. After the extraction of the Bauxite, it must be converted to Alumina by the Bayer Process, a process patented in 1888 and is still used today. This process begins when bauxite is smashed by being mixed with soda ash and lime in a ball mill. Water is added to turn the mixture into a slurry, which is drained from the ball mills into tanks or digestures. In these tanks, which are injected with steam, the alumina is turned into a creamy slurry and poured into a settling tank. In these tanks, the heavier metals and sand sink to the bottom, while the alumina remains on top. Once this tank is cleared of all the solids, the liquid is poured into a large vat. It is here that the alumina crystals begin to form. Agitation causes the crystal to cling to each other as they slowly begin to fall to the bottom of the vat. They are then subject to cleansing by the same ash and lime solution that was added at the beginning of the process.
The final step is to drive off the remaining moisture by passing the alumina, which now looks like white mud, through kilns that heat it to more than 1000 deg C (1830 deg F). When it is dry, and about 99 percent pure, it is stored in silos, ready for the next process that turns the alumina into aluminum.
This next step is called the Hall-Heroult process. The smelting takes place in huge pots in which molten cryolite is poured. Electricity is then passed through the cryolite to form a crust. When this crust is formed, the alumina is then poured into the crust. The electric current is passed through the crust causing the oxygen to be driven off the alumina, leaving the aluminum atoms in a molten state collecting at the bottom of the pots. The aluminum is then transported into a holding furnace where it may be alloyed before being poured into holding tanks.
Although pure aluminum has working and forming properties, it has low mechanical strength, and therefore must be strenghened by alloying before it can be used. Aluminum alloys are divided into two basic types, casting and wrought alloys. Casting alloys contain silicon, magnesium, copper, zinc, or nickel. This improves its corrosion resistance, strength, and stability.
Wrought alloys are alloys that have been mechanically worked after casting, including forging, rolling,
Aluminum has a variety of uses because of its properties. Perhaps the best known is that it is very light weight. It is only about one-third less dense than iron, copper, and zinc. Aluminum also has the highest strength to weight ratio of any of the commercial metals. Also, aluminum and its alloys are highly resistant to corrosion and are extremely conducive to electricity. It is because of these properties that industry has made many advances in technology.
Aluminum is increasingly used to conserve energy both in home heating and cooling.
Aluminum storm doors, insulation, and aluminum siding are excellent insulators. Also because vehicle weight is a determinant in gas mileage, aluminum is being substituted for heavier materials. The container packaging industry is by far the biggest user of aluminum, using about thirty percent of the United states production of aluminum, and most of this is in the production of aluminum cans.
Since aluminum is a potentially non-renewable resource, we need to do a better job at the recycling of this material. Not enough people know that it is cheaper for the aluminum companies to recycle than it is to process the Bauxite. Recycling costs only about five percent of the energy originally used to make aluminum because we eliminate the mining, shipping, refining, and reduction process. Aluminum companies say it takes about half the time and costs about one-tenth the money then to produce aluminum from the ore. Recycling also saves energy and other fossil fuels used to produce aluminum. Also, large aluminum recycling companies, such as the Reynolds Aluminum Recycling Company of America, has paid out as much as one billion dollars to consumers since the late sixties.
If you would like to start your recycling campaign in your city, you should consider these facts: Identify the aluminum recycling centers in your area and ask them if they offer any assistance to groups recycling as a fund raising project. If you cannot find any in your local directory, you can get in touch with the Department of Agriculture. They will have a list of centers. Then try to recruit the aid of your local businesses that sell aluminum cans. They can make your job easier by keeping the cans in separate containers until you can pick them up. Try to pass out other information about your project at local supermarkets and other high visibility areas to help promote the program. You could also use the local media. Newspapers, radio, and the television are excellent means of getting attention. Last, but certainly not least, is to recycle wisely. Wait until you have an abundance of material to bring to the recycling center so you do not waste time and gas and make recycling a little bit more enjoyable for everyone involved.
Xavier, I hope I gave you a little more information then you already had. If you need any additional information, you could get in touch with the Reynolds Aluminum Recycling Company of America for tips to construct your program. Lorin Industries could also help since they are the worlds largest job shop anodizer of aluminum. As for myself, I could just call any of my references that I leave on the bottom of this letter if I need any additional information. Take care pal and I will see you very soon. PEACE!
Eric
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2. Ammen, C. W., Casting Aluminum, (1985).
3. Bakker, M., Encyclopedia of Packaging Technology, (1986).
4. Burkin, R. R. Production of Aluminum and Alumina, (1987).
5. King, F., Aluminum and its Alloys, (1987).
6. Pampillo, C. And Biloni, H., Aluminum Transformation Technology and Applications, (1980).
7. Peck, M. J., ed., World Aluminum Industry in a Changing Era, (1988).