Aluminum production involves energy-intensive but highly optimized processes.
First, bauxite mining: Australia, Guinea, and China produce 85% of the world's bauxite, often through open-pit mining.
Second, the Bayer process refines bauxite into alumina (Al₂O₃) by dissolving it in caustic soda, filtering out impurities like iron oxide.
Third, the Hall-Héroult process electrolyzes alumina in molten cryolite (950°C), splitting it into molten aluminum and CO₂. This stage consumes 13–15 MWh per ton, relying heavily on hydropower in countries like Norway and Canada.
Fourth, alloying adds elements (e.g., magnesium for strength, silicon for castability) to meet application-specific needs.
Fifth, recycling reprocesses scrap into new products, reducing reliance on virgin ore. Challenges include managing toxic "red mud" waste and cutting CO₂ emissions (1 ton of aluminum emits 12 tons of CO₂ if coal-powered). Innovations like carbon capture and inert anodes aim to decarbonize this sector.
