Session: 17-04: Symposium Steinfeld - New solar chemical processes and cycles

Paper Number: 137199

137199 - Thermodynamic and Experimental Study on Carbothermal Reduction of Jsc-1a Lunar Regolith Simulant for Metal and Metalloid Production 

Abstract: 

Lunar in-situ resource utilization is essential for maintaining a human presence on Moon. The extraction of valuable metals and metalloids contained in lunar regolith as oxides are of particular interest, including Si, Fe, Ti, K, and Ca, which are integral for the development of perovskites for optical glass and other industrial and scientific infrastructures [1]. The carbothermal reduction of JSC-1A lunar simulant with activated carbon was investigated for producing metals and metalloids. Sample mixtures of JSC-1A and stoichiometric activated carbon (C to JSC1A mass ratio of 0.3191) were used in all experiments and analysis. Chemical equilibrium compositions were examined using Gibb’s free energy minimization to identify favorable operating temperatures at 0.1, 10^-8, and 3×10^-15 bar for Fe and Si production. This thermodynamic analysis was also used to identify favorable reaction pathways and intermediaries as a function of temperature and pressure. The temperature range studied was 0 ≤ T^eq ≤ 2000 °C. Complete conversion of Fe₂O₃ to Fe(g) was predicted at temperatures above 850 °C and about 90% conversion of SiO₂ to Si(g) was predicted at temperatures above 1000 °C for lunar surface pressure of 3×10^-15 bar. SiO and SiC were favorable intermediaries in Si production processes. Thermogravimetry was used to examine the reactions with mixtures of JSC-1A and stoichiometric activated carbon in 100% Ar up to 1500 °C, and comparisons between temporal mass losses and CO evolution were used to estimate volatile production. CO evolution from mixtures of JCS-1A and activated carbon accounted for about 45% of sample mass loss whereas the remaining 55% was estimated as volatiles. Solid-state surface material characterization was performed on samples using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, and transmission electron microscopy to identify elemental distributions, chemical compositions, and particle morphologies before and after experimentation. Solid-state characterization provided strong evidence of reactions of Si-, Fe-, and Ti- compounds in JSC-1A. Characterization on the loose sample after TGA confirmed the presence of crystalline SiC, Si, and Fe, and Mg₂SiO₄ was observed in the melted sample after TGA indicating no reaction occurred with olivine. Ultra-high vacuum experiments at 10^-12 bar imitating the low-pressure lunar conditions were conducted with temporal CO measured and volatiles collected using copper foils. Comparisons with thermogravimetry results were made. Deposits collected on copper foils mounted above the sample in the ultra-high vacuum experiments were found to contain Fe-, Al-, Mg-, and Si- volatiles at temperatures ≥ 1250 °C. Future experiments involving other types of simulants (e.g.: LMS-1, LHS-1) using a tube furnace for the benefit of bulk sample capabilities will be conducted to extend the investigation and analysis.

 

Reference

[1] CRAWFORD, I. A. 2015. Lunar resources: A review. Progress in Physical Geography: Earth and Environment, 39, 137-167.

Presenting Author: Shaspreet Kaur Georgia Institute of Technology

Presenting Author Biography: Shaspreet is a Ph.D. graduate student at Georgia Institute of Technology working on metal and metalloid production from lunar soil using solar-driven carbothermal reduction processes which involves thermodynamic, experimental, and solid-state surface material characterization work. She has also worked on studying water vapor transport through lunar regolith simulants and two-step chemical looping cycle for renewable Solar-Thermal Ammonia Production (STAP).

Authors:

Shaspreet Kaur Georgia Institute of Technology
Alexandr Aleksandrov Georgia Institute of Technology
William Ready Georgia Institute of Technology
Thomas Orlando Georgia Institute of Technology
Peter Loutzenhiser Georgia Institute of Technology