Experimental optimisation of lunar regolith beneficiation for the production of an ilmenite-rich feedstock

Abstract

In recent years, significant progress has been made in the space industry to pave the way for long-term human space exploration missions. The Moon has emerged as a focal point of interest, driving technology development and serving as a crucial stepping stone for future exploration endeavours throughout our solar system and beyond. To ensure the sustainable settlement of humans in space, the development of In-situ Resource Utilisation (ISRU) technologies is imperative to enable self-sufficiency in long-duration space missions. The lunar regolith contains essential minerals that hold promise for supporting human space settlements. Amongst them, ilmenite is of significant value for in-situ oxygen production on the lunar surface due to the higher oxygen yield that it provides compared to other minerals. However, the distribution of ilmenite is not uniform across the lunar surface and thus, the raw regolith requires additional processing to achieve sustainable extraction efficiency. This pre-processing is called beneficiation which encompasses activities that help in concentrating a raw material with the mineral of interest using different strategies depending on the material properties. Although being an essential part of ISRU, beneficiation as a research area has often been overlooked, while the attention of the scientific community mainly focused on the preceding and subsequent steps, i.e., excavation and extraction. The Synergetic Material Utilization research group at DLR Bremen has been working on the development of ISRU technologies to support sustainable human space exploration in the future. In this research group, a laboratory-scale multi-stage lunar regolith beneficiation test bed has been developed for producing an ilmenite-rich feedstock for the subsequent oxygen extraction process. Along with them, the Exploration and Propulsion Group at TU Berlin is also involved in the development of ISRU technologies. An integral part of their research is the production of lunar simulants that allow for the testing of the ISRU technologies. The research produced in this work is an outcome of collaboration between both research groups. This research begins with an extensive review of prior scientific research on lunar regolith beneficiation to establish a comprehensive understanding of the process. The stages of the testbed are then discussed, highlighting the crucial process parameters necessary for achieving optimisation. Experimental analysis is conducted using different configurations of these parameters to determine the one that produces the desired beneficiation results. To ensure result repeatability, experiments are performed using LMS-1 simulant and TUBS-M based modular regolith simulant. Additionally, secondary results, such as total energy consumption and material residuals, are analysed to gain insights into the system’s overall performance and behaviour during continuous operation. The primary objective of this research is to validate and optimise the beneficiation testbed, ensuring the production of the desired output feedstock. Furthermore, this work strives to address existing knowledge gaps in the field of beneficiation and lay the groundwork for future advancements.