Mining on the Moon will provide oxygen, water, and building materials that enable the further exploration of space by humankind. The production of oxygen from lunar soil, called regolith, has received particular attention in recent years as it can be used both for life support and propellant for further missions. The overall flowsheet to produce oxygen from lunar regolith similar to that of metal production from a mined ore on Earth. The process flowsheets both include excavation and beneficiation of the regolith or ore to provide the feedstock for the chemical extraction of oxygen or metal.
For example, hydrogen reduction of the lunar regolith produces oxygen by reduction of ilmenite. Lunar regolith contains less than a few percent ilmenite and must be upgraded first. Additionally, sizing to remove coarse and fine fractions is also required to control the feedstock into the reactor. Terrestrial mineral processing technologies will not work directly on the Moon, due to the low gravity, lack of atmosphere and, critically, the lack of water. Dry processing is the only viable route for regolith beneficiation. Electrostatic and magnetic beneficiation are of particular interest, as they does not require a process fluid and is enhanced by the absence of water. Furthermore, ilmenite is amenable to concentration using electrostatic methods, as is used for beach sands on Earth.
In this presentation, we discuss the issues and potential for regolith beneficiation on the Moon. We look at the likely scale of lunar mining operations, and illustrate some of the sizing and beneficiation techniques required. In particular, we assess the potential for crossover of technologies and operational concepts into more sustainable terrestrial mining operations.