HallHéroultprosessilla

The HallHéroult process is the primary industrial method for producing aluminum. It was developed independently by Charles Martin Hall in the United States and Paul Héroult in France in 1886. This electrolytic process involves dissolving alumina (aluminum oxide) in molten cryolite (sodium aluminum fluoride) at high temperatures, typically around 950-980 degrees Celsius. This molten mixture acts as an electrolyte.

During the process, a strong electric current is passed through the electrolyte using carbon anodes and a carbon-lined cathode. At the cathode, aluminum ions (Al3+) are reduced to molten aluminum metal, which collects at the bottom of the electrolytic cell. At the anode, oxygen ions from the alumina react with the carbon anode, producing carbon dioxide gas. This leads to the gradual consumption of the carbon anodes, which must be periodically replaced.

The raw materials for the HallHéroult process are bauxite ore, from which alumina is extracted through the Bayer process, and carbon-containing materials for the electrodes. The process is highly energy-intensive, requiring significant amounts of electricity, which is why aluminum smelters are often located near sources of cheap hydroelectric power. The purity of the produced aluminum is typically very high, around 99.5% to 99.9%. The HallHéroult process revolutionized aluminum production, transforming it from a precious metal to a widely used, versatile material.