How does electrolysis produce magnesium metal from magnesium chloride?

Electrolysis is the primary method for extracting magnesium metal from magnesium chloride. The process occurs in two main stages: feedstock preparation and electrochemical dissociation.1

The Electrolytic Process

Industrial production utilizes electrolytic cells, which are brick-lined vessels containing a molten salt electrolyte—a mixture of alkaline chlorides. Magnesium chloride is added to this bath in concentrations ranging from 6 to 18 percent.1

The cells are equipped with steel cathodes and graphite anodes. When an electric current is applied at operating temperatures between 680 and 750 °C (1,260 to 1,380 °F), the magnesium chloride dissociates:1

• At the Anodes: Chlorine gas is generated. This gas is often captured and reused in the dehydration phase of the process.1
• At the Cathodes: Molten magnesium metal is produced. Because the metal is less dense than the salt bath, it floats to the surface, where it is collected.1

This method is highly energy-intensive, typically requiring 12 to 18 kilowatt-hours of electricity for every kilogram of magnesium produced.1