National Geographic : 1937 Sep
BAUXITE. The commonly used ore. It is found in many countries. Ours comes from Arkansas and Dutch Guiana. Aluminum is present, not as metal, but in the form of complicated chemical compounds. All the follow ing raw materials are needed to get the aluminum out: SODA ASH AND LIME. Add water to these, heat the solution and digest the bauxite in it. Aluminum com pounds dissolve. Impurities are left behind as mud. From the filtered solution, something called aluminum hydrate is separated. Heat the hydrate to drive out water, and you have alumina, a white powder, chemically labelled as aluminum oxide. It sounds simple, but this is really a very tech nical, expensive process. CRY OLITE. Translucent "Ice-rock," found naturally only in distant Green land, but also made synthetically. To get the actual metal out of the alumina, the powder first has to be dissolved in a bath of molten cryolite. COKE, TAR AND PITCH. Metallic aluminum is made in a steel pot thickly lined with carbon, which contains the molten bath of cryolite and dissolved alumina. Carbon blocks are hung in the bath, and a heavy electrical current is passed from the blocks through the bath to the lining of the pot. This current changes the oxide, alumina, to the metal, aluminum. Carbon blocks and linings are made from coke, tar and pitch. A total of nine pounds of thefore going materials are required to make one pound of aluminum. But other things are equally vital: FU EL. The process of getting alumina from bauxite uses 22,000 cubic feet of gas, or equivalent coal, for each ton of final metal. Coal also is consumed in baking the carbon blocks used in the reduction pots. ELECTRICITY. Twelve kilowatt hours of electrical energy must be generated to produce one pound of aluminum. The energy needed for a ton of aluminum would supply the electrical needs of the average home for thirty-five years. That is why we have invested millions in dams, reser voirs and power houses, through which, when running full, flows enough water to supply the needs of 92 cities the size of New York. TRANSPORTATION. From mine to refinery to reduction plant our alumi num-in-the-making has to be shipped and reshipped to locations where all these raw materials are best available. Our transportation bill, just for getting aluminum made, was more than $5,000,000 last year. LABOR. Labor is important in every one of these operations. Wages con stitute the largest item in the cost of making aluminum. SKILL. Every step of the process must be supervised and co-ordinated by men who "know-how." Hundreds of men in laboratories must continual ly check not only the raw materials but every pound of metal produced. MONEY. The wherewithal which de velops mines, builds and equips the necessary refinery and reduction plants, the dams, reservoirs and power houses, must be available. All these are needed to make virgin aluminum, one of the most difficult of allcommercialmetals to extractfrom nature. Would you have imagined it?