Hall–Héroult process

The Hall–Héroult process is the major industrial process for smelting aluminium. It involves dissolving aluminium oxide (alumina) (obtained most often from bauxite, aluminium's chief ore, through the Bayer process) in molten cryolite and electrolyzing the molten salt bath, typically in a purpose-built cell. The process, conducted at an industrial scale, happens at 940–980 °C (1700–1800 °F) and produces aluminium with a purity of 99.5–99.8%. Recycling aluminum, which does not require electrolysis, is thus not treated using this method.

The Hall–Héroult process consumes substantial electrical energy, and its electrolysis stage can produce significant amounts of carbon dioxide if the electricity is generated from high-emission sources. Furthermore, the process generates fluorocarbon compounds as byproducts, contributing to both air pollution and climate change.