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Processes for the electrowinning of metals and oxygen from lunar regolith

: Dietz, A.; Moustafa, E.

Abstract ()

Electrochemical Society. ECS Meeting abstracts (2019), Nr.2, Abstract 2442
ISSN: 1091-8213
ISSN: 2151-2043
Electrochemical Society (ECS Meeting) <236, 2019, Atlanta/Ga.>
Abstract, Elektronische Publikation
Fraunhofer IST ()

One of the great goals of manned space flight is the colonization of the moon. It can serve as a rocket launch pad for deep space missions, or for the development of new processes under reduced gravity. Tourism can also be a worthwhile goal. For the scientific and economic development of the moon, large quantities of different materials are necessary, which cannot be transported from the earth for cost reasons. This concerns materials for the construction of accommodation for astronauts and other infrastructures. Regolith, the easily available upper powdery layer of the Moon, can be used to build houses, roads, etc. For this purpose, processes such as additive manufacturing are under investigation. In addition, pure metals like iron or aluminium for the construction of tools and machines as well as oxygen as breathing air and fuel are needed. These can also be obtained from regolith. Regolith consists of the oxides of silicon, iron, titanium, aluminium, magnesium and other materials. By means of a combined process, the components of regolith are chemically dissolved and electrochemically extracted as metal (cathodic process) and oxygen (anodic process). The aim is to develop an almost closed process for the electrowinning of metal and oxygen, which only requires the regolith without any additional consumables. The process is based on the use of so-called Ionic Liquids (IL), which are transported once from the earth. IL serve as solvents for the chemical dissolution of the oxides. In addition, they are also the electrolyte for the electrochemical production of metal and oxygen. Ionic liquids are salts that are present in liquid form at room temperature or slightly higher temperatures and are very stable electrochemically. In addition, they have a very low vapour pressure. Since Ionic Liquids do not participate directly in the electrochemical reaction, they are not consumed. This is a great advantage compared to the known aqueous electrochemical processes, in which hydrogen is often produced as a by-product at the cathode. This consumes the water as electrolyte. In addition, the electrochemical production of aluminum, an important raw material in the regolith, from aqueous electrolytes is not possible. The oxygen obtained, can be used as breathing air. In addition, in combination with water it can also be further processed electrochemically to hydrogen peroxide, H₂O₂. H₂O₂ can be used as fuel for mobility on the moon, but also as fuel for other rockets, e.g. for deep space missions. The lecture presents the principle and discusses first results.