Lunar soil water production, oxygen release and dressing-smelting integrated treatment method based on flash Joule heating

Abstract

The invention discloses a lunar soil water production, oxygen release and dressing-smelting integrated treatment method based on flash Joule heating. The method comprises a first stage and a second stage. In the first stage, instantaneous desorption water production is carried out, specifically, lunar soil is placed in a flash Joule heating device, high-power pulse current is applied within the time from the millisecond level to the second level, hydrogen in the lunar soil is instantaneously desorbed, and water molecules are generated; and in the second stage, a new round of pulse current is applied, high-temperature pulse induces iron-containing oxide in the lunar soil to be subjected to extremely rapid reduction reaction, lattice oxygen is released immediately, and metal iron is generated through reduction. According to the treatment method, 'lunar soil water production ', 'lunar soil oxygen release' and'resource beneficiation and smelting 'are organically combined, the function of extracting key resources from the lunar soil is achieved in one set of process, reaction is rapid and efficient, the system is simple and reliable, the method is suitable for the in-situ resource taking requirement of a future lunar base, and the wide application prospect is achieved.

Description

Technical Field

[0001] This invention relates to an integrated treatment method for lunar soil water production, oxygen release, and beneficiation based on flash Joule heating (FJH), belonging to the field of lunar in-situ resource utilization technology. Background Technology

[0002] Lunar water resources are a key constraint for the survival and expansion of future lunar bases. Previous hypotheses have focused on frozen water in the permanently shadowed polar regions, but recent sample evidence suggests that the lunar regolith may also constitute exploitable "dispersed water reservoirs." Taking the Chang'e-5 return samples as an example, impact glass beads and major oxygen-containing minerals can capture hydrogen under long-term solar wind injection, with the hydrogen existing in the form of hydroxyl groups / water-like molecules; reported water release amounts reach the level of "tens of milligrams per gram," making "in-situ heating-hydrogen release-water formation" a feasible path. However, conventional external furnace-type long-term constant-temperature heating is subject to thermal inertia and limited heat transfer control, resulting in accumulated heat loss, slow kinetics, and equipment size and thermal control / sealing complexity that are difficult to adapt to the lunar surface boundary.

[0003] Traditional routes for producing oxygen from lunar soil mainly include: hydrogen reduction of oxygen-containing minerals such as ilmenite to generate water, followed by electrolysis to obtain oxygen; and high-temperature electrolysis of molten lunar soil to directly produce oxygen. The former has strong compositional adaptability, while the latter does not rely on chemical reducing agents. However, both generally depend on sustained high temperatures and long reaction times: hydrogen reduction requires continuous hydrogen supply and temperature maintenance, making the process slow and energy-intensive; molten electrolysis requires maintaining high temperatures for extended periods and faces engineering challenges such as bubble management and material durability. Therefore, breakthroughs are still needed in "reaction time, energy utilization, and equipment deployment."

[0004] Joule heating is the process by which electrical energy is directly converted into heat energy when an electric current passes through a resistive medium. Macroscopically, this satisfies V=IR, and the instantaneous power is P=VI=I. 2 R=V 2 / R. The energy deposited during the pulse duration t is approximately: Q = ∫Pd ≈ R. 2 Ri. For the reaction zone, the resistance is determined by geometry and resistivity, R = ρL / A, while ρ varies with temperature and structural evolution, forming an "electrothermal coupling" feedback, making the temperature rise steeper under flash conditions. From a mechanistic perspective, Joule heating can be considered as a volumetric heat source term, with current density J = σE, and heat generation per unit volume: q′′′ = J·E = σE 2 =J 2 Substituting / σ into the energy equation, it can be written as: 𝜌𝐶 𝑃𝜕𝑇 / 𝜕𝑡=∇∙(𝑘∇𝑇)+𝑞′′′−𝑞l𝑜𝑠𝑠. Under millisecond-second pulses, 𝜕𝑇 / 𝜕𝑡 dominates, and heat cannot be conducted externally in time, thus achieving an ultra-fast heating rate of 3000℃ within milliseconds. This generates hotspots in non-uniform resistivity regions such as particle contact points, enhancing desorption, reduction, and phase transition processes. Mechanistically, pulsed body heating using flash Joule heating provides a valuable approach for the synergistic production of multiple lunar regolith resources. Furthermore, research on titanomagnetic ore has revealed that FJH can achieve instantaneous ultra-high temperatures within seconds, directly activating lattice oxygen and enhancing solid-solid reactions, rapidly completing Fe... 3+ Reduction. More importantly, FJH significantly improves conductivity and reactivity, reducing the activation energy to 41.9 kJ / mol, demonstrating a clear advantage in cost assessment. The above results indicate that the framework of "short-time high-power pulse-rapid cooling capture-separation and recovery" holds promise for more efficient coupling of water release, oxygen release, and metal recovery on the lunar surface, avoiding the energy consumption and complexity bottlenecks of traditional long-term high-temperature systems. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention provides an integrated method for water production, oxygen release, and beneficiation from lunar soil based on flash Joule heating, enabling the rapid and efficient simultaneous extraction of water, oxygen, and metallic iron resources from lunar soil. This method aims to overcome the drawbacks of traditional processes, such as slow reaction times, high energy consumption, and limited output, achieving second-level reaction, efficient energy utilization, and synergistic production of multiple resources to meet the needs of In-Situ Lunar Resource Utilization (ISRU).

[0006] This invention is achieved through the following technical solution: An integrated treatment method for lunar soil water production, oxygen release, and beneficiation based on flash Joule heating includes a first stage and a second stage, as shown in the schematic diagram below. Figure 1 As shown; The first stage, instantaneous desorption for water production: Lunar soil containing hydrogen injected by the solar wind is placed in a flash Joule heating device. A high-power pulsed current is applied within milliseconds to seconds, instantly raising the temperature of the lunar soil to 2000-3000 K. This rapid thermal pulse causes the hydrogen (including "solar wind hydrogen" existing in the form of H or H2) residing on the glassy phase or particle surface of the lunar soil to be instantly desorbed and combined with hydroxyl groups on the surface of oxides in the lunar soil to form water molecules. The desorbed water vapor and other volatile components are then cold-captured to obtain liquid water. Through this stage of treatment, a considerable amount of water resources can be recovered from the lunar soil. The second stage, reduction and oxygen release smelting: The lunar soil treated in the first stage (where most of the free hydrogen has been removed) is placed in a flash Joule heating device, placing it in an inert atmosphere composed of inert gas, which contains no hydrogen or only a small amount of hydrogen. A new round of pulsed current is applied, instantly raising the temperature of the lunar soil to a high temperature, followed by rapid cooling and quenching. The high-temperature pulse induces an extremely rapid reduction reaction of the iron oxides in the lunar soil: iron is reduced from the high-valence state Fe(III) to Fe(II) and metallic iron Fe. 0 Lattice oxygen is then released; when the inert gas does not contain hydrogen, the released oxygen is free in the form of gaseous oxygen; when the inert gas contains hydrogen, the released oxygen immediately combines with hydrogen to generate water vapor, thus capturing the produced gaseous oxygen or water vapor; at the same time, the reduced metallic iron precipitates out in the form of fine particles in the solid product; through the rapid cooling and quenching of the reaction products in this stage, the valence state and phase structure of the intermediate products can be locked, and the gaseous products can be separated from the solid products.

[0007] Furthermore, before heating, the lunar soil is pretreated: it is placed in a pretreatment unit and baked at low temperature in a vacuum or inert environment to remove physically adsorbed water, thereby ensuring that the water subsequently obtained mainly comes from the endogenous hydrogen and oxygen resources of the lunar soil.

[0008] Furthermore, the flash Joule heating device is a flash Joule heating reactor.

[0009] Furthermore, a condensation system is used for cold capture. The condensation system includes two-stage cold traps. During cold capture, the water vapor is first cooled in the first cold trap to condense most of the water vapor, and then cooled in the second cold trap to 10-20 K to capture the uncondensed residual volatile gases, ensuring that the water is collected quantitatively.

[0010] Furthermore, the aforementioned small amount of hydrogen refers to a volume percentage of 2% to 5% hydrogen.

[0011] Furthermore, a gas collection device is used to capture water vapor, and a condensation system is used to capture gaseous oxygen.

[0012] Furthermore, the iron oxide in the lunar soil is ilmenite, whose main component is FeTiO3.

[0013] Furthermore, solid products are processed using methods such as magnetic separation to enrich and separate the generated metallic iron, thereby achieving effective separation and recovery of metallic iron from residual minerals (titanium-rich components such as TiO2).

[0014] The present invention provides an integrated treatment method for lunar soil water production, oxygen release, and beneficiation based on flash Joule heating. This method treats lunar soil in two stages and has advantages such as rapid reaction, low energy consumption, and integrated functions, as detailed below: 1. Second-level reaction time: The reaction duration of each stage is only in the milliseconds to several seconds, significantly shortening the processing cycle. Compared with traditional processes that require several hours of continuous heating, this invention can complete the desorption water production and reduction oxygen release processes instantly, improving treatment efficiency.

[0015] 2. Low cumulative energy consumption: Flash Joule heating uses strong pulsed energy supply instead of long-term constant energy supply, avoiding overheating of the reaction vessel and surrounding medium, and reducing ineffective heat loss. Therefore, the overall energy consumption requirement is significantly reduced, making it suitable for the energy supply conditions on the lunar surface (utilizing lunar solar energy). This invention has low energy consumption per unit of water and oxygen production and high energy utilization efficiency.

[0016] 3. Modular equipment facilitates deployment: The FJH device has a compact structure, short and discontinuous reaction time, which facilitates modular design and intermittent operation, and can be integrated as a standard module of the lunar ISRU system. The equipment can be powered by electricity (solar energy converted to electrical energy), eliminating the need for large continuous furnaces or complex electrolyzers, thus making it easier to transport, install, and maintain on the lunar surface.

[0017] 4. Simultaneous Acquisition of Multiple Resources: The processing method of this invention can simultaneously obtain three resources—water, oxygen, and metallic iron—in a single process, achieving comprehensive resource utilization. The water produced in the first stage can supply astronauts with living support or be used for oxygen and hydrogen production via electrolysis; the oxygen released in the second stage can be used for life support or rocket propellant; and the byproduct metallic iron can be used for lunar surface construction, equipment manufacturing, etc. Compared to traditional methods that produce only one resource at a time, the processing method of this invention significantly improves the comprehensive utilization efficiency of lunar soil resources.

[0018] In summary, the integrated lunar soil water production, oxygen release, and resource beneficiation method based on flash Joule heating of this invention organically combines "lunar soil water production," "lunar soil oxygen release," and "resource beneficiation," realizing the function of extracting key resources from lunar soil in a single process. The reaction is rapid and efficient, the system is simple and reliable, suitable for the on-site resource access needs of future lunar bases, and has broad application prospects.

[0019] The various terms and phrases used in this invention have their general meanings known to those skilled in the art. Attached Figure Description

[0020] Figure 1 Flowchart of an integrated lunar soil water production, oxygen release, and beneficiation treatment method based on flash Joule heating Figure 1 .

[0021] Figure 2 Flowchart of an integrated lunar soil water production, oxygen release, and beneficiation treatment method based on flash Joule heating Figure 2 .

[0022] The components include: 1. Flash Joule heating reactor; 2. Electrode assembly; 3. High-power pulse power supply; 4. Conductive medium; 5. Lunar soil; 6. Pretreatment unit; 7. First cold trap; 8. Second cold trap; 9. Collector; 10. Gas collection device; 11. Pressure monitoring unit; 12. Flow control unit; 13. Magnetic separation device; 14. Magnetic concentrate; and 15. Non-magnetic residue. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments. However, the scope of the present invention is not limited to the following embodiments. Those skilled in the art will understand that various changes and modifications can be made to the present invention without departing from the spirit and scope thereof.

[0024] Unless otherwise specified, the instruments, reagents, and materials used in the following embodiments are all conventional instruments, reagents, and materials already available in the prior art and can be obtained through legitimate commercial channels. Unless otherwise specified, the experimental methods and detection methods used in the following embodiments are all conventional experimental methods and detection methods already available in the prior art.

[0025] Example 1: Integrated Treatment Method for Lunar Soil Water Production, Oxygen Release, and Smelting Based on Flash Joule Heating An integrated treatment method for lunar soil water production, oxygen release, and beneficiation based on flash Joule heating includes a first stage and a second stage, and the treatment process is as follows: Figure 2 As shown.

[0026] The first stage, instantaneous desorption water production: The lunar regolith to be treated can be selected from the weathered layer of the lunar surface, containing hydrogen elements retained due to long-term solar wind injection (hydrogen contained in glassy microspheres and mineral lattices in the lunar regolith). Before heat treatment, the lunar regolith is pretreated: it is placed in pretreatment unit 6 and baked at low temperature in a vacuum or inert environment to remove physically adsorbed water, thereby ensuring that the water subsequently obtained mainly comes from the hydrogen and oxygen resources endogenous in the lunar regolith. Lunar soil 5 was placed in a flash Joule heating reactor 1. A high-power rectangular current pulse (50-300 A) was applied to the lunar soil 5 between the electrode components 2 at both ends of the flash Joule heating reactor 1 through a high-power pulse power supply 3. The sample itself or the mixed conductive medium 4 was used as a resistive heating element. The instantaneous large current heated the lunar soil to a high temperature of over 2000 K in a very short time (milliseconds to 1 second). Under such steep heating conditions, the hydrides, hydroxyl groups on the surface of the lunar soil particles and the adsorbed hydrogen in the glass phase rapidly dissociated and desorbed. Some hydrogen escaped in the form of molecular hydrogen, while some hydrogen combined with oxygen on the surface of oxides in the lunar soil to form water molecules and immediately vaporized. To collect the water vapor generated during desorption, the outlet of the flash Joule heating reactor 1 can be connected to a condensation system. This condensation system includes two cold traps: during cold capture, the water vapor is first cooled to approximately 77 K in the first cold trap 7 (liquid nitrogen cold trap) to condense most of the water vapor, and then cooled to 10–20 K in the second cold trap 8 to further capture any uncondensed residual volatile gases, ensuring that water is collected quantitatively. After condensation in the cold traps, the water collects in collector 9 as ice or liquid water.

[0027] The second stage, oxygen release and smelting: After the first stage is completed, the residual lunar soil retained in the flash Joule heating reactor 1 continues to be processed in the second stage. First, the ambient gas in the reactor (1) is adjusted to an inert atmosphere (high-purity argon) or a weakly reducing atmosphere (containing 2% to 5% hydrogen by volume, with the remainder being argon). The atmosphere pressure can be monitored by the pressure monitoring unit 11 installed in the flash Joule heating reactor 1, and the gas flow rate can be controlled by the flow control unit 12. Then, a flash Joule heating current pulse is applied to the electrode assembly 2 again through the high-power pulse power supply 3 (the current amplitude and duration can be the same as or higher than the first stage), so that the sample temperature rises sharply to 2000 to 3000 K again in a short time. Under this instantaneous high temperature condition, the ilmenite in the lunar soil undergoes oxygen desorption and reduction-related reactions: a portion of the ilmenite is reduced to generate metallic iron and low-valence titanium oxide and releases oxygen atoms; if hydrogen is present in the atmosphere, the released oxygen atoms react with hydrogen to generate water vapor; if it is a pure inert atmosphere, the oxygen atoms combine to form oxygen and escape. Because both the heating and power-off cooling processes are extremely short, the products do not have time to continue reacting or rearranging at high temperatures, thus achieving the process characteristics of "ultra-fast reduction-rapid quenching," which is beneficial for improving reaction efficiency and avoiding over-reaction. The generated gaseous products can be collected by the gas collection device 10 or further condensed and captured by cold traps: under a hydrogen-containing atmosphere, the main product is water vapor, which can be condensed by the first cold trap 7 and the second cold trap 8 and finally collected into the collector 9; under an inert atmosphere, the main product is oxygen, which can be collected by cold trap condensation or compression. After the second stage of processing and cooling, the reaction solid products contain metallic iron and other mineral residues. Since metallic iron is ferromagnetic, the cooled solid products can be sent to the magnetic separation device 13 for magnetic separation, thereby obtaining magnetic concentrate 14 (mainly metallic iron) and non-magnetic residue 15.

[0028] Process Conditions and Modular Implementation: The processing method of this invention employs flash Joule heating technology, which offers high flexibility. Parameters can be adjusted according to lunar soil composition and resource acquisition needs. For example, the peak temperature and heating rate can be controlled by changing the pulse current amplitude and duration; the processing intensity can be controlled by adjusting the number of pulses and the pulse interval. Typically, the duration of a single pulse can range from tens of milliseconds to several seconds, achieving a peak temperature >2000 K and a heating rate as high as 10⁻⁶ K / L. 3 ~10 5The FJH system achieves transient heating and reaction of lunar regolith at a speed of K / s. Due to the extremely short processing time per cycle, an intermittent batch processing mode can be adopted: lunar regolith is fed into the reaction chamber in batches, undergoes two-stage pulse processing, and then the solid products are unloaded and water / oxygen is collected before a new batch of regolith is loaded and the process is repeated. This cyclical operation mode is ideal for situations where lunar surface power supply is limited and peak energy usage needs to be staggered. Furthermore, the FJH equipment has a compact structure, integrating the power supply, reaction chamber, and condenser into one unit. Each module can process a certain amount of lunar regolith, and multiple modules connected in parallel can increase the overall processing capacity, exhibiting excellent scalability. The method of this invention does not require large, continuous high-temperature furnaces or complex piping. In fact, the low-gravity vacuum environment of the lunar surface makes it easier to achieve high-temperature instantaneous heating and rapid cooling with minimal disturbance to the surrounding environment. These characteristics make it highly suitable for deployment in lunar rovers, landers, or fixed bases, gradually establishing a production chain for the on-site utilization of lunar regolith resources.

[0029] The above embodiments are provided to those skilled in the art to fully disclose and describe how to implement and use the claimed embodiments, and are not intended to limit the scope of the disclosure herein. Modifications that will be obvious to those skilled in the art will be within the scope of the appended claims, such as adjusting pulse parameters according to lunar soil composition, selecting different inert gas media, adding small amounts of conductive additives, or placing them in conductive crucibles and conductive heating chambers to improve lunar soil conductivity.

Claims

1. A method for integrated treatment of lunar soil water production, oxygen release, and beneficiation based on flash Joule heating, characterized in that: Including Phase 1 and Phase 2; The first stage, instantaneous desorption for water production: Lunar soil is placed in a flash Joule heating device, and a high-power pulsed current is applied within milliseconds to seconds, causing the temperature of the lunar soil to rise instantaneously to 2000-3000 K. This rapid thermal pulse causes the hydrogen residing in the glass phase or particle surface of the lunar soil to be instantly desorbed and combine with hydroxyl groups on the surface of oxides in the lunar soil to form water molecules; the desorbed water vapor and other volatile components are cold-captured to obtain liquid water; The second stage, reduction and oxygen release smelting: The lunar soil treated in the first stage is placed in a flash Joule heating device, placing it in an inert atmosphere composed of inert gas, which contains no hydrogen or only a small amount of hydrogen. A new round of pulsed current is applied, instantly raising the temperature of the lunar soil to a high temperature, followed by rapid cooling and quenching. The high-temperature pulse induces an extremely rapid reduction reaction of the iron oxides in the lunar soil: iron is reduced from the high-valence state Fe(III) to Fe(II) and metallic iron Fe. 0 The lattice oxygen is then released; when the inert gas does not contain hydrogen, the released oxygen is free in the form of gaseous oxygen; when the inert gas contains hydrogen, the released oxygen immediately combines with hydrogen to generate water vapor, thus capturing the produced gaseous oxygen or water vapor; at the same time, the reduced metallic iron precipitates out in the form of fine particles in the solid product.

2. The integrated treatment method for lunar soil water production, oxygen release, and beneficiation based on flash Joule heating according to claim 1, characterized in that: Before heat treatment, the lunar soil is pretreated by placing it in a pretreatment unit and baking it at low temperature in a vacuum or inert environment to remove physically adsorbed water.

3. The integrated treatment method for lunar soil water production, oxygen release, and beneficiation based on flash Joule heating according to claim 1, characterized in that: The flash Joule heating device is a flash Joule heating reactor.

4. The integrated treatment method for lunar soil water production, oxygen release, and beneficiation based on flash Joule heating according to claim 1, characterized in that: A condensation system is used for cold capture. The condensation system includes two-stage cold traps. During cold capture, the gas is first cooled in the first cold trap to condense most of the water vapor, and then cooled in the second cold trap to 10-20 K to capture the uncondensed residual volatile gases.

5. The integrated treatment method for lunar soil water production, oxygen release, and beneficiation based on flash Joule heating according to claim 1, characterized in that: The aforementioned small amount of hydrogen refers to a volume percentage of 2% to 5% hydrogen.

6. The integrated treatment method for lunar soil water production, oxygen release, and beneficiation based on flash Joule heating according to claim 1, characterized in that: A gas collection device is used to capture water vapor, and a condensation system is used to capture gaseous oxygen.

7. The integrated treatment method for lunar soil water production, oxygen release, and beneficiation based on flash Joule heating according to claim 1, characterized in that: The iron oxide in the lunar soil is ilmenite, and its main component is FeTiO3.

8. The integrated treatment method for lunar soil water production, oxygen release, and beneficiation based on flash Joule heating according to claim 1, characterized in that: The solid product is treated by magnetic separation to enrich and separate the generated metallic iron.

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