Oxygen and Metal Coproduction

Because many minerals consist of metal oxides, we can utilize them to produce both oxygen and metals. This scheme, first explored in 1971, passes an electric current through a molten silicate to release oxygen at the anode. Metals, both iron and silicon, are produced at the cathode. This metal layer can be tapped off into ingots for a variety of needs. There may also be a layer of slag which can be used for the production of bricks. Thus, three separate products can be made in one unit. This process is performed at high temperatures, and the stability of the materials used in many of the components of the plant requires further research before a viable process can be claimed . As in most other proposed routes to oxygen, the electric power requirements for such a unit are considerable.

The actual chemical mechanisms that occur are quite complex; however, the reactions can be written as

SiO2 --> Si + O2

FeO --> Fe + 1/2 O2

Thus, an alloy of iron and silicon is produced as a coproduct. An alloy of aluminum and silicon has also been produced in a laboratory investigation of a related process aimed at the production of metals from lunar materials. Alloys such as these can be further processed to provide construction materials for structures or interior articles.

Another route to oxygen electrolysis of the lunar regolith is shown here. This involves processing molten soil to release oxygen, iron, and silicon. A slag which can be used for brick fabrication is also produced. The amount of mining required to produce each ton of oxygen is lower for this route than for many other potential processes. Much development work will be required to take this chemistry from the research stage to that of a reliable process.