Novel process for enhanced lunar oxygen recovery

The generally accepted method for recovering oxygen on an extraterrestrial body is by thermal reduction of indigenous minerals, the most amenable of which is ilmenite, FeTiO₃. Thermodynamic modelling shows that carbon is a more effective reductant than hydrogen. In this paper the effect of extended ball milling on the carbothermic reduction of a terrestrial beach sand derived ilmenite is examined. The rate of oxygen recovery into the gas phase is substantially faster for powders milled together and a concomitent lowering of onset temperature is also noted. XRD examination of the final powders indicate that reduction of ilmenite proceeds via elemental iron and rutile which is then further reduced to sub-oxides. The presence of nitrogen, or excess carbon, leads to vastly greater oxygen recovery due to the formation of titanium nitride or carbide with complete release of oxygen from the mineral achieved in 1 h at 1200°C.