Concentrating CaO from Lunar Simulant by Calciothermic Reduction Process

The lunar regolith can be utilized as raw materials for constructing lunar bases through the fabrication of lunar cement. However, the low CaO content in lunar regolith presents a challenge for producing silicate cement. This study explores enriching CaO in NEU-1 lunar soil simulant by calciothermic reduction. Non-isothermal differential scanning calorimetry analysis indicated that calcium reacted with Fe 2 O 3 , SiO 2 , and Al 2 O 3 at approximately 808°C, 816°C, and 826°C, respectively. The reaction ratios were 1.1, 1.6, and 0.8, with apparent activation energies of 941.6 kJ/mol, 965.17 kJ/mol, and 547.28 kJ/mol. The products obtained from the calciothermic reduction of lunar soil simulant were CaO, Ca 2 Si, and AlFe, as analyzed by X-ray diffraction. Increasing the temperature was found to be beneficial to the reaction process, and a suitable reaction temperature of 850°C was determined. X-ray photoelectron spectroscopy analysis showed that the reduction percentages of SiO 2 and Al 2 O 3 were 93.01% and 91.04%, respectively, at 850°C for 30 min. The CaO content in the product obtained by calciothermic reduction was 50.65%, which could be further increased to 81.16% after crude purification, and the CaO yield was 82.57%. These results demonstrated that the process has a significant CaO enrichment effect.