Aluminum

History

Throughout antiquity, people used alum as an astringent and as an ingredient in ceramics. It was not until 1807, however, that Sir Humphrey Davy proposed that alum contained a base metal, which he called “aluminum.” In 1827, chemists Hans Orsted and Frederich Wohler isolated pure aluminum for the first time using electrolysis, but the process was slow and costly. In the mid-19th century, pure aluminum was considered as precious and rare as gold or silver. This notion changed in the 1880s, when chemists Charles Martin Hall and Paul Héroult, working independently in the United States and France, perfected a quicker and more efficient process of electrolyzing aluminum. The Hall-Héroult process ushered the transition of aluminum from precious metal to industrial element, and it remains a primary method in aluminum extraction.

Mining

Most aluminum in the Earth's crust resides in bauxite. Bauxite occurs naturally throughout most of the globe, but a great deal of the world's supply lies in developing areas, including Jamaica, Guinea, Brazil, China, and India. For people in these countries, bauxite mining presents a potential path to employment and economic development, but the benefits of mining have come with social and environmental costs.

Bauxite mining is an open-pit process, which means that topsoil and vegetation must be removed in order to obtain ore. The refining process requires the use of caustic sodium hydroxide, which yields valuable aluminum oxide and an alkaline toxic waste. This alkaline waste, known as “red mud,” has some industrial applications, but it has also been a source of groundwater contamination in bauxite mining countries.

Both the refining process and the subsequent electrolysis by the Hall-Héroult process consume tremendous amounts of electricity. To provide this energy, governments and mining interests have built hydroelectric dams near bauxite sources. Even though they may provide local people with cheaper sources of power, dams are not always popular.

In the Indian state of Orissa, for example, ethnographers and activists contend that the aluminum industry and its dams have led to the displacement of thousands of adivasi, or “tribal,” groups. They suggest that the forced relocation of people who live in bauxite-rich regions presents an economic and ecological burden that outweighs the benefits of aluminum extraction.

Recycling

Though bauxite mining remains a primary source of aluminum, industry leaders and environmentalists now recognize that it may be cheaper and more energy efficient to obtain aluminum by recycling. Aluminum is 100 percent recoverable, meaning it can be recast without any loss of its prized shine and malleability. Aluminum has a low melting point relative to other commonly used metals (about 600 degrees Celsius, or 1,200 degrees Fahrenheit). When heated, aluminum liquefies, leaving a small amount of waste product, called “dross.” This dross can be further refined to recover pure aluminum.

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