A novel strategy to extract lunar mare KREEP-rich metal resources using a silicon collector

Abstract

The lunar mare potassium (K)-, rare-earth elements (REEs)- and phosphorous (P)-rich (KREEP-rich) region is a unique late-stage product of magma crystallization, in which ilmenite and incompatible elements have high grades, thus forming a giant natural reservoir. The extraction and purification of the high-value metal resources in the KREEP-rich region not only meet the construction needs of the lunar base but also solve the problem of resource scarcity on Earth. In this study, photovoltaic elemental silicon (Si) was used as a collector to extract ilmenite resources, REEs, and nuclear energy elements from basalt in the lunar mare KREEP-rich region at 1873 K. Based on experimentation, the metals titanium (Ti) and iron (Fe) in the lunar mare ilmenite are found to be enriched and solidified in the form of Si-based alloys. The contents of valuable incompatible elements in the KREEP-rich area are also found to be enriched and contained in the incompatible trace elements (ITEs) phase of the alloy. Among them, REEs (e.g., cerium (Ce) and thulium (Tm)) and nuclear elements (e.g., thorium (Th) and uranium (U)) are found to account for 82.61 wt% of the ITEs phase. This process provides a simple and feasible scheme for the in-situ resource utilization (ISRU) of the lunar surface and is suitable for the extraction and enrichment of lunar metal resources.