Reductant-Free Laser-Vacuum Ironmaking Technology for Lunar In-Situ Resource Utilization

In-situ resource utilization (ISRU) is crucial for the sustainable construction of lunar bases. Based on the high-vacuum environment of the lunar surface, vacuum pyrolysis is endowed with a distinct advantage in extracting metals from lunar regolith. Nevertheless, this technique presents issues of metal re-oxidation and physical volatilization during product collection. This study altered the product collection method for vacuum pyrolysis of simulated lunar regolith (CLRS-2) by combining laser heating with a “cold crucible” effect. This approach effectively prevented metal re-oxidation and reduced physical volatilization, while it achieved efficient, reductant-free decomposition of iron oxides in the simulated lunar regolith along with elemental iron enrichment. Microstructural analysis and thermodynamic calculations indicated the mechanisms underlying the decomposition of iron oxide clusters within the melt pool and the growth of elemental iron. Moreover, this study also proposed an in-situ molten slag coverage method to suppress volatilization during vacuum pyrolysis. The results showed that under 1 × 10–3 Pa, this method increased the product yield by approximately 2.4 times and raised the elemental iron yield to 18.2%, representing an increase of 10.5 times over the slag-free process. It effectively inhibited melt volatilization and enhanced elemental iron yield, offering a reference technique for future in-situ lunar metal extraction.