Darren McWhirt, age 13, of Cushing, Okla., for his question:
HOW IS ALUMINUM MADE?
When scientists first discovered aluminum in the 1800s, it was rare and costly. The first object ever made of the metal was a toy rattle made for Napoleon's baby son in 1854. A German immigrant named William Frismuth made the cap for the Washington Monument in 1884. Weighing 100 ounces, the pyramid shaped cap was the largest piece of aluminum made in the United States.
Aluminum is a strong, rustproof, light metal. Because it can be stretched or rolled into almost any shape, the silvery white metal is often called the magic metal.
In Canada and the United States the metal is pronounced " uh loo mih num. " In Great Britain and many other foreign countries the people pronounce it " al yoo min ih um. "
Aluminum as a metal isn't found in nature. It must be manufactured from bauxite ore. About 35 percent of the world's aluminum is produced in the United States each year with Russia, Australia, Canada, France, Japan, Norway and West Germany following as other leading producers.
Aluminum must be separated from other materials in bauxite ore before pure aluminum metal can be manufactured. The electrochemical treatment needed to make aluminum is expensive because it takes a lot of electric power. Aluminum plants are usually built near rivers that can provide lots of power, since hydroelectric power is the cheapest source of electrical energy.
After bauxite ore reaches the mill, sprayers wash off the clay and dirt. Belts then carry the ore into crushing machines where the ore is ground into powder. The powder is mixed with hot caustic soda solution and pumped into large pressure tanks.
The tanks, called digesters, hold the 300 degree Fahrenheit mixture for 30 minutes until the alumina dissolves. Pumps push the solution through pressure filters.
The impurities, called red mud, are removed and the remaining liquid is moved to tanks called precipitators where the solution is stirred for two days until it cools slowly. It then comes out of solution as it cools. Crystals of hydrated alumina are added and the alumina in the solution grows on the seed crystals. The crystallized alumina finally settles on the bottom of the tank.
It takes four tons of bauxite to make two tons of alumina, which in turn makes about one ton of aluminum metal.
Aluminum is produced with smelters that dissolve the alumina into a cryolite solution in an electrolytic cell. Aluminum forms at the cathode.
Workmen add other metals to form aluminum alloys.
Aluminum is produced in ingot, plate and sheet form. It is also extruded to form tubes and rods