How aluminum is made

 

 Aluminum

Aluminum is the third most abundant element in the earth's crust, accounting for 8 percent of the planet's soil and rocks (oxygen and silicon make up 47 percent and 28 percent , respectively). Aluminum is only found in nature as a component of chemical compounds with elements such as sulphur, silicon, and oxygen. Aluminum metal can only be economically extracted from aluminium oxide ore.

Metallic aluminium possesses numerous properties that make it applicable to a vast array of applications. It is light, resilient, nonmagnetic, and nontoxic. It also reflects heat and light and conducts heat and electricity. It retains its strength in extreme cold without becoming brittle, despite being both robust and easily worked. The aluminium surface oxidises rapidly to form an invisible barrier against corrosion. In addition, aluminium can be economically and easily recycled into new products.

Background

Aluminum compounds have demonstrated their utility for millennia. Around 5000 BCE, the Persian potters created their most durable vessels from clay containing aluminium oxide. The ancient Egyptians and Babylonians employed aluminium compounds in textile dyes, cosmetics, and medicines. In contrast, aluminium was not identified as an element and isolated as a pure metal until the early nineteenth century. After half a century of its discovery, aluminium remained as rare and valuable as silver due to the difficulty of separating it from its naturally occurring compounds.

In 1886, two 22-year-old scientists independently invented a smelting technique that made aluminium mass production economically feasible. The Hall-Heroult process, named after its American and French inventors, remains the primary method for producing aluminium today. The 1888 invention by an Austrian chemist of the Bayer process for refining aluminium ore contributed significantly to the economical mass production of aluminium.

In 1884, the United States produced 125 pounds (60 kilogrammes) of aluminium, which sold for roughly the same unit price as silver. In 1995, U.S. plants produced 7.8 billion pounds (3.6 million metric tonnes) of aluminium, and silver was priced seventy-five times higher than aluminium.

Unprocessed Materials

Aluminum compounds are present in all types of clay, but bauxite is the most valuable ore for producing pure aluminium. In addition to 45 to 60 percent aluminium oxide, bauxite contains sand, iron, and other metal impurities. Although some bauxite deposits are composed of hard rock, the vast majority consist of relatively soft soil that is easily excavated from open-pit mines. Australia produces over one-third of the world's bauxite supply. Approximately four pounds of bauxite are required to produce one pound of aluminium metal. KMC aluminium Company is best aluminium extrusion profiles manufacturers in India.

The aluminium compounds in the bauxite are dissolved with caustic soda (sodium hydroxide) in order to separate them from the impurities. Depending on the bauxite ore's composition, relatively small amounts of other chemicals may be used in the extraction process.


Aluminum is produced in two stages: the Bayer process, which refines bauxite ore to produce aluminium oxide, and the Hall-Heroult process, which smelts aluminium oxide to produce pure aluminium.

Aluminum-based. Examples are starch, lime, and sodium sulphide.

In the smelting process, the electrolyte (current-carrying medium) is cryolite, a chemical compound composed of sodium, aluminium, and fluorine. Historically, cryolite was extracted from Greenland, but it is now manufactured synthetically for use in the production of aluminium. Aluminum fluoride is added to lower the electrolyte solution's melting point.

Carbon is the other major component of the smelting process. Electrodes made of carbon conduct the electric current through the electrolyte. Carbon is consumed during the smelting process as it combines with oxygen to form carbon dioxide. In actuality, roughly a half-pound (0.2 kg) of carbon is used to produce every pound (2.2 kg) of aluminium. Some of the carbon used in aluminium smelting is a byproduct of oil refining, while the remainder comes from coal.

Due to the fact that smelting aluminium involves passing an electric current through a molten electrolyte, it requires a substantial amount of electrical energy. The average amount of energy required to produce 2 lb (1 kg) of aluminium is 15 kilowatt-hours (kWh). The cost of electricity accounts for approximately one-third of the total cost of aluminium smelting.