Lunar Titanium Production
The main source of Lunar Titanium is in the form of Ilmenite (FeTiO3). This material is found abundantly on the lunar surface, especially on the Maria. Being weakly magnetic, Ilmenite could be concentrated from the lunar regolith in a magnetic separator (a multistage device may be necessary due to other magnetic minerals present). There are several ways Titanium could be produced in a Lunar environment.
The titanium tetrachloride is separated from the other reaction products by distillation. Once separated, is is reacted with liquid magnesium in the Kroll process, producing titanium metal and magnesium chloride:
The resulting sponge of titanium metal is then either crushed and washed or subjected to vacuum distillation to remove the magnesium chloride, and then melted and further refined to the desired purity.
It is possible to adapt this process to a lunar environment, though it presents some challenges. The chlorine and carbon required in the process would have to be stringently recycled, as they are rare (and hence likely to be quite expensive) in a lunar environment. The magnesium and iron chlorides could be electrolyzed to their respective metals, recovering the chlorine, and the carbon monoxide can be reacted with hydrogen to produce methane and water. The methane can then be split through pyrolysis back into hydrogen and carbon, and the water electrolyzed to recover the hydrogen as well as oxygen stripped from the Ilmenite.
see also: Hydrogen Reduction
Ilmenite could be reacted with hydrogen directly, producing iron, titanium dioxide, and water. The resulting product could then be finely ground and passed over a magnet to remove the iron, leaving titanium dioxide, which would then be refined by other means. The water would be split to recover the hydrogen and produce oxygen.
FFC Cambridge Process
Main Article: FFC Cambridge Process.
The FFC Cambridge Process is a method of performing electrolysis on solid metal oxides. The developers believe it has potential to replace the Kroll Process for terrestrial titanium production, due to its greater simplicity.
In this process, the oxide to be reduced is formed into a cathode and subjected to electrolysis in a molten calcium chloride bath. Oxygen is stripped off and bubbles off at the anode, leaving behind a metallic sponge.
The FFC Cambridge process could be used on the titanium dioxide produced from hydrogen reduction of Ilmenite, or the Ilmenite could be directly reduced, producing an Iron-Titanium alloy. This could then be melted and distilled under partial vacuum to produce iron and titanium.
Recovery of the chlorine is greatly simplified by the FFC Cambridge process compared to the Kroll Process, as the chlorine remains chemically bound to the calcium throughout the whole procedure. Furthermore, calcium chloride is not soluble in most metals, and is highly soluble in water, enabling separation by washing and/or melting.