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, it 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 would need to be electrolyzed to their respective metals, recovering the chlorine. Recovering the carbon and oxygen from the carbon monoxide is a bit less straightforward, though several methods exist.
see also: Hydrogen Reduction
Ilmenite could be reacted with hydrogen, producing iron and titanium dioxide. The iron could then be separated by carbonyl extraction, distillation, or by grinding and removing the iron particles with a magnet. The titanium dioxide would then be refined by other means.
FFC Cambridge Process
Main Article: FFC Cambridge Process.
The FFC Cambridge Process is a method of performing electrolysis on solid metal oxides. 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, which is then separated by carbonyl extraction or distillation.