Occupational exposure to aluminum and its compounds and their health effects

Abstract

Initially aluminum was very expensive to manufacture, but towards the end of the 19th century production on commercial scale became feasible. The production of aluminum increased rapidly in the 20th century, especially after the Second World War period. In the 1970s and early 1980s, approximately 15 million tons were produced per annum. Aluminum is produced from bauxite, a mineral containing aluminum oxide, ferrous oxide and silica. Bauxite is abundant in the earth’s crust in large areas of the world. Refining is carried out by means of a chemical process to leach out and sediment aluminum in the form of aluminum oxide. Pure aluminum is then produced using an electrothermal process, where electrolysis takes place in a carbon-lined steel reservoir containing molten cryolite (Na3Al6). Carbon anodes are dipped into the liquid molten cryolite. A direct current is passed through the cell resulting in formation and liberation of carbon dioxide at the anodes and production and collection of molten aluminum at the bottom of the cell, whose carbon lining serves as the cathode. The current used is about 100,000 A with a cell voltage of approximately 5 V. Enormous quantities of energy are necessary for the electrolytic reduction of aluminum, almost 16,500 kWh are utilized in the production of one metric ton of the metal. Due to this fact, aluminum plants are usually located close to relatively cheap power sources, e.g. in the vicinity of hydro-electricity plants.