Ground and parabolic flight testing of a magnetic and electrostatic separation system for lunar regolith beneficiation

Abstract

We present an end-to-end design, build, and testing, of a regolith beneficiation system under both Earth gravity and simulated lunar gravity. The system combines a dual-stage magnetic separator followed by an electrostatic sieve to enrich high-value minerals from bulk lunar regolith simulant, targeting plagioclase feldspar which spans the solid-solution series between anorthite and albite. The magnetic separator consists of a dual-strength set of N-52 and N-42 neodymium permanent magnets to sort the simulant particles based on their magnetic susceptibility. The downstream electrostatic sieve separates particles by size using a single-phase 50% duty-cycle wave with a peak voltage between 3.0 kV and 6.0 kV and operating frequencies ranging from 15 Hz to 30 Hz. The combined system produces four output streams: concentrated iron particulates, bulk basalt, and two sized anorthite fractions according to a target particle size range. The design objective was to obtain an anorthite-rich feedstock exceeding 70 wt% within a 20μm to 200μm size range. A prototype unit was first designed, built, and tested under Earth gravity to prove the concept. Then an adapted unit was built and tested under simulated lunar gravity through parabolic flights. Experiments using multiple lunar regolith simulants under both Earth and reduced-gravity conditions demonstrate consistent mineral and size separation, with improved performance observed under lunar gravity. X-ray Diffraction (XRD) with Rietveld refinement confirmed the success of the reduced-gravity separation: for the L2W60-g814 Mare simulant, plagioclase increased from 35.5 wt% in the feed to 70.6 wt% in the recovered product, approximately doubling its concentration and meeting the system design objective. Pyroxene and olivine, initially present in the feed, were not detected above the approximate XRD detection limit in the reduced-gravity product. These results demonstrate that combined magnetic and electrostatic beneficiation can successfully produce a concentrated plagioclase-rich feedstock under lunar-relevant gravity conditions, supporting its use as a front-end process for lunar in-situ resource utilization (ISRU) such as downstream aluminum and oxygen extraction and additive manufacturing.