Aluminum and oxygen production by electrolysis after aluminothermic reduction of lunar soil simulant in cryolite melts

The combined process of aluminothermic reduction, electrodeposition alloying, and molten salt electrolysis using inert anode provides a viable pathway for producing Al and O 2 from lunar soil simulant. Utilizing the electrolyte derived from aluminothermic reduction of lunar soil simulant in cryolite molten salt as raw material, electrodeposition alloying was employed to reduce the concentrations of impurity elements Si, Fe, and Ti in the electrolyte. The influence of cell voltage and electrodeposition time on the impurity removal rates were investigated. The results indicate that increasing the cell voltage from 1 V to 4 V reduced the mass fraction of SiO 2 in the upper molten salt from 2.09 wt% to 1.06 wt%, and extending electrodeposition time from 1 h to 4 h decreased SiO 2 mass fraction from 1.64 wt% to 0.96 wt%. Under the optimal electrodeposition conditions (3.5 V, 3 h), the removal rates of Si, Fe, and Ti elements in the electrolyte were 68.53 %, 89.53 %, and 85.00 %, respectively. The cathode products obtained by electrodeposition contained Si, MoSi 2 , Mo 5 Si 3 , and FeSi 2 alloys. Subsequently, electrolysis was performed using purified alumina-rich cryolite molten salt with a 57 wt% Fe-43 wt% Ni inert anode. The cathode product was a 91.49 wt %Al-4.44 wt% Fe-3.86 wt% Si alloy, achieving a cathode current efficiency of 40.79 %. When the inert anode electrolysis process stabilized, the volume fraction of O 2 in the anode gas was kept above 90 %, and the anode current efficiency tended to be above 50 %.