Aluminiumgewinnung

Aluminiumgewinnung refers to the industrial process of extracting aluminium from its ore, primarily bauxite. This process is crucial for obtaining the metal, which is widely used in various industries due to its lightweight, strength, and corrosion resistance. The extraction is a complex and energy-intensive undertaking.

The primary ore for aluminium is bauxite, a rock rich in aluminium oxides. The first major step involves purifying the bauxite to obtain pure aluminium oxide, commonly known as alumina. This is achieved through the Bayer process, where bauxite is treated with a hot solution of sodium hydroxide. Aluminium oxides dissolve, while impurities remain undissolved. The dissolved alumina is then precipitated out and calcined to form pure alumina.

The next and most significant stage is the electrolytic reduction of alumina to aluminium metal. This is carried out using the Hall-Héroult process. Alumina is dissolved in molten cryolite, which acts as a solvent and reduces the operating temperature. An electric current is passed through the molten mixture using carbon electrodes. At the cathode, aluminium ions are reduced to molten aluminium, which collects at the bottom of the electrolytic cell. At the anode, oxygen ions react with the carbon electrodes, producing carbon dioxide.

The molten aluminium is then tapped from the cells, cast into ingots, and further processed or alloyed for specific applications. The energy required for the electrolytic reduction is substantial, making the location of aluminium smelters often dependent on access to affordable electricity. Recycling of aluminium also plays a significant role in aluminium production, as it requires considerably less energy compared to primary extraction.