Aluminum

Al	13
Aluminium

Abundance: 8,1% crust

Aluminum, periodic table Al, is the third most common element in the Martian crust, after oxygen and Silicon.

Aluminum oxides are abundant on Mars as on Earth. Most aluminum is incorporated into alumina-silicate minerals, such as feldspar ((KAlSi₃O₈ – NaAlSi₃O₈ – CaAl₂Si₂O₈). Erosion, either by wind or water, can separate out the alumina, possibly as fine dusts that would have turned into compact silts and clays over time. This might be a useful source of aluminum ore.

Production of aluminum

For in-situ production, a source of aluminum ore such as alumina deposits would be very helpful in reducing the processing requirements.

Traditionally aluminum requires high electric power to reduce it from its oxides using electrolysis. Work has been going on for several decades on the carbothermic process, which uses carbon and just thermal power, to try to make it as economical on Earth as electrolytic reduction. If thermal power is cheaper than electric power on Mars relative to Earth, due for example to being more suitable for an import-minimizing economy, the carbothermic process will be relatively more attractive. Of course carbon itseld would need to be produced on Mars, which has no handy coal reserves as a carbon source. Methane might be a practical alternative, if methane clathrates, for example, are found on Mars.

Alcoa has announced in 2018 the production of aluminum using a new electrolytic process that does not produce CO₂ or require carbon anodes. This might be applicable on Mars.

Once it has been produced, aluminum is relatively easy to recycle and less prone to corrosion than iron and steel.

The embodied energy of aluminum is 155 MJ/kg. (To be confirmed may include recycled aluminum).

Uses

• Construction material, window and door frames
• Mobile equipment
• Cans