Method and device for preparing metallic iron and oxygen through electro-deposition of lunar soil in three-electrode fused salt system

Abstract

The invention discloses a method and device for preparing metallic iron and oxygen through electro-deposition of lunar soil in a three-electrode fused salt system, and belongs to the technical field of metallurgy. The device comprises a threaded pipe sealing structure, a gas inlet and outlet structure, a reaction cavity, a crucible, a reaction cavity sealing cover and a three-electrode potential control system. The method comprises the following steps: adding chloride molten salt, a cosolvent and lunar soil / simulated lunar soil into a crucible; raising the temperature to a drying temperature in a simulated moon atmosphere, and keeping the temperature to remove moisture; continuously raising the temperature to the electro-deposition temperature, so that iron-containing components in the lunar soil / simulated lunar soil are fully dissolved; a three-electrode system is adopted for electro-deposition, high-purity metal iron is obtained at a working electrode, and oxygen is efficiently separated out at an auxiliary electrode. The reduction potential is accurately regulated and controlled through a three-electrode system, and synchronous and efficient separation of metal iron and oxygen in lunar soil / simulated lunar soil is achieved.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and particularly relates to a method and apparatus for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system. Background Technology

[0002] In recent years, with the rapid development of aerospace technology, establishing a permanent base on the lunar surface and realizing in-situ resource utilization has become a core mission of deep space exploration. However, if the key metals (such as Al, Si, Fe) and oxygen required for lunar base construction were transported from Earth, the cost would be as high as 10... 5 With prices per kilogram in US dollars, coupled with limitations imposed by both carrying capacity and the extreme lunar environment, the traditional Earth-Moon resupply model is unsustainable.

[0003] Lunar regolith, a core resource for in-situ development and utilization on the Moon, is primarily composed of olivine (Mg,Fe)₂SiO₄, plagioclase CaAl₂Si₂O₈, and pyroxene (Ca,Fe,Mg)₂Si₂O₆. Its chemical composition includes 45.0 wt% SiO₂, 27.3 wt% Al₂O₃, 5.1 wt% FeO, and 15.7 wt% CaO, providing natural conditions for the preparation of metals and oxygen via electrodeposition. Molten salt electrodeposition, in particular, dissolves the metal-containing components in lunar regolith into molten CaCl₂ salt. Using electrical energy to drive a redox reaction, metals and oxygen can be generated simultaneously without the need for additional reducing agents. This method is especially suitable for the abundant solar power available on the Moon and is widely recognized as one of the most promising technologies for achieving this goal.

[0004] Currently, in electrolytic methods for separating metals and oxygen from lunar regolith, the metal products obtained by most methods exist in alloy form due to the inability to precisely control the electrode potential. Furthermore, the alloy composition is constrained by the original composition of the lunar regolith, making it difficult to control both its composition and properties. For example, in patent CN119800453A, the product composition of Example 1 is Si. 32.46wt％ -Ti 2.14wt％ -Fe 11.04wt％ -Al 44.39wt％ The product of Example 2 has a composition of Si. 31.7wt％ -Ti 0.16wt％ -Fe 11.72wt％ -Al 54.21wt％ The product of Example 1 in patent CN114592215A is Fe. 11.06wt％ -Al 33.54wt％ -Si 55.40wt％ The product of Example 2 is Fe. 21.31wt％ -Al 21.27wt％ -Si 57.42wt％ All of these reflect the aforementioned problems.

[0005] To address the aforementioned issues, developing technologies that can precisely control the electroreduction process and achieve controllable product composition is a key breakthrough for the efficient utilization of in-situ lunar resources in the future. There is an urgent need to optimize electrode systems and process schemes to selectively separate and precisely purify mineral resources in lunar soil, directly obtaining metal materials and oxygen with controllable composition, providing core support for lunar base construction and resource recycling. Summary of the Invention

[0006] To address the problems of complex product composition and low separation efficiency in existing lunar in-situ resource utilization technologies, this invention proposes a method and apparatus for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system. By precisely controlling the reduction potential window, iron-containing components in lunar soil / simulated lunar soil are selectively reduced, achieving the simultaneous preparation of high-purity metallic iron and oxygen. This method effectively suppresses the co-deposition of impurities such as silicon and aluminum through real-time feedback adjustment of the reference electrode, ensuring a single and controllable product composition.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] One objective of this invention is to provide an apparatus for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system, comprising:

[0009] The threaded tube sealing structure has a through hole at the top for placing the electrode and is connected to the sealing cover of the reaction chamber by threads.

[0010] Gas inlet and outlet structure, used to introduce a simulated lunar atmosphere;

[0011] The reaction chamber is connected to the reaction chamber sealing cover by threads;

[0012] The crucible is placed at the bottom of the reaction chamber;

[0013] The three-electrode system includes an auxiliary electrode, a working electrode, and a reference electrode. Each electrode consists of a current collecting rod and an electrode head, which are inserted into the reaction chamber through a through hole.

[0014] Furthermore, the reaction chamber is made of a high-temperature resistant material, which is selected from at least one of quartz, corundum, and stainless steel; and / or,

[0015] The material of the current collecting rod is selected from at least one of molybdenum rod, tungsten rod, and stainless steel rod; and / or,

[0016] The electrode head is made of at least one material selected from graphite, Fe-Ni alloy, and cermet; that is, the working electrode is graphite; the auxiliary electrode is Fe-Ni alloy; and the reference electrode is a high-purity graphite rod.

[0017] The second objective of this invention is to provide a method for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system, employing the aforementioned apparatus, specifically including the following steps:

[0018] S1. Mix the chloride molten salt, flux and lunar soil / simulated lunar soil and put them into a crucible. Place the crucible at the bottom of the reaction chamber, heat it to the drying temperature under a simulated lunar atmosphere and keep it at that temperature to remove residual moisture from the chloride molten salt.

[0019] S2. Continue heating to the electrodeposition temperature under a simulated lunar atmosphere and hold the temperature to dissolve the iron-containing components in the molten salt;

[0020] S3. Electrodeposition of iron-containing components in chloride molten salt is performed using an auxiliary electrode, working electrode, and reference electrode system. Electrodeposition is carried out through a three-electrode system, with metallic iron deposited on the working electrode and oxygen evolved on the auxiliary electrode.

[0021] The device provided by this invention includes a threaded pipe sealing structure, a gas inlet and outlet structure, a reaction chamber, a crucible, a reaction chamber sealing cover, and a three-electrode potential control system consisting of a working electrode, an auxiliary electrode, and a reference electrode. Using this device, iron-containing components in lunar regolith / simulated lunar regolith are selectively separated through the following method: First, chloride molten salt, a fluxing agent, and lunar regolith / simulated lunar regolith are added to the crucible within the reaction chamber; the temperature is raised to a drying temperature under a simulated lunar atmosphere and held to completely remove residual moisture from the molten salt; the temperature is further raised to the electrodeposition temperature, allowing the iron-containing components in the lunar regolith / simulated lunar regolith to fully dissolve in the molten salt system; finally, electrodeposition is performed using a three-electrode system, resulting in a high-purity metallic iron deposition layer at the working electrode while oxygen is efficiently released at the auxiliary electrode. Traditional molten salt electrolysis methods for utilizing lunar regolith resources suffer from limitations in selectively controlling the reaction process, resulting in metallic products that typically exist in alloy form, with their composition highly dependent on the raw material composition ratio, thus limiting the applicability of the products. This invention achieves simultaneous and efficient separation of metallic iron and oxygen in lunar soil / simulated lunar soil by introducing a three-electrode system and precisely controlling the reduction potential.

[0022] Further, the chloride molten salt includes one or more of LiCl, KCl, NaCl, RbCl, CaCl2, SrCl2, and BaCl2; and / or,

[0023] The co-solvent includes one or more of NaOH, CaO, MgO, and BaO.

[0024] Further, by mass fraction, the chloride molten salt comprises 80-94 wt%, the co-solvent 3-10 wt%, and lunar soil / simulated lunar soil 3-10 wt%.

[0025] Furthermore, the simulated lunar atmosphere includes an argon atmosphere and / or a nitrogen atmosphere.

[0026] Further, the specific drying operation steps are as follows: heating to 300-500℃ at a heating rate of 4℃ / min, and maintaining at this temperature for 12 hours; and / or,

[0027] The specific steps for heating to the electrodeposition temperature and holding at that temperature are as follows: heat to 800-900℃ at a heating rate of 10℃ / min, and hold at that temperature for 12 hours.

[0028] Further, the electrodeposition voltage is -0.8 to -1.2V, and the time is 2-5 hours; and / or,

[0029] The electrodeposition mechanism is a constant voltage mode and / or a pulsed electrodeposition mode.

[0030] A third objective of this invention is to provide an application of the aforementioned device in the simultaneous preparation of metallic iron and oxygen during in-situ resource utilization on the moon.

[0031] The fourth objective of this invention is to provide an application of the above-mentioned method in separating metallic components from lunar soil / simulated lunar soil.

[0032] Compared with the prior art, the present invention has the following advantages and technical effects:

[0033] This invention innovatively proposes and develops a precise control technique for electrodeposition potential based on a three-electrode system. By employing a potential feedback system constructed using a reference electrode, millivolt-level precise control of the reduction potential of the working electrode is achieved. In multi-component complex mineral phase systems, this technique successfully achieves selective electrochemical reduction of iron components; and by controlling the potential of Fe through the three-electrode system... 2+ At the working electrode, it gains electrons and is eventually reduced to metallic iron, O. 2- Oxygen is generated when electrons are lost at the auxiliary electrode.

[0034] Thermodynamic calculations revealed that the reduction voltage of iron-containing components in lunar soil / simulated lunar soil in the molten salt system differs significantly from that of other metals. This provides a larger electrochemical window for the reduction of iron-containing components, making it less prone to co-reduction with other metals while generating metallic iron. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0036] Figure 1 This is a schematic diagram of the apparatus for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system according to the present invention.

[0037] Wherein, 1 is the threaded pipe sealing structure; 2 is the gas inlet and outlet structure; 3 is the reaction chamber; 4 is the crucible; 5 is the auxiliary electrode; 6 is the working electrode; 7 is the reference electrode; 8 is the reaction chamber sealing cover; 1-1 is the connecting thread; 1-2 is the through channel; 8-1 is the thread;

[0038] Figure 2 This is a schematic diagram of the process for preparing metallic iron and oxygen from lunar soil by molten salt electrodeposition according to the present invention;

[0039] Figure 3 XRD pattern of simulated lunar soil for NEU-1a;

[0040] Figure 4 In the image, (A) is the XRD pattern of the metallic iron prepared in Example 1, and (B) is a comparison chart of the ICP elemental ratio detection data of the metallic iron prepared in Example 1 with the product composition of patents CN114592215A and CN108505070A.

[0041] Figure 5 (A) is the XRD pattern of metallic iron prepared in Example 2, and (B) is a comparison chart of the ICP elemental ratio detection data of metallic iron prepared in Example 2 with the product composition of patents CN114592215A and CN108505070A.

[0042] Figure 6 In the image, (A) is the XRD pattern of the metallic iron prepared in Example 3, and (B) is a comparison chart of the ICP elemental ratio detection data of the metallic iron prepared in Example 3 with the product composition of patents CN114592215A and CN108505070A.

[0043] Figure 7 The reduction voltage of different metal oxides in molten salt at 500-1000℃ was theoretically calculated. Detailed Implementation

[0044] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0045] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0046] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0047] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and its embodiments are merely illustrative.

[0048] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0049] This invention provides an apparatus for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system (see [reference]). Figure 1 ),include:

[0050] The threaded tube sealing structure 1 has a through hole 1-2 at the top for placing an electrode, and is connected to the reaction chamber sealing cover 8 by a thread 8-1.

[0051] Gas inlet / outlet structure 2, used to introduce a simulated lunar atmosphere;

[0052] The reaction chamber 3 is connected to the reaction chamber sealing cover 8 via thread 8-1;

[0053] Crucible 4 is placed at the bottom of reaction chamber 3;

[0054] The three-electrode system includes an auxiliary electrode 5, a working electrode 6, and a reference electrode 7. Each electrode consists of a current collecting rod and an electrode head, and is inserted into the reaction chamber 3 through the through holes 1-2.

[0055] The reaction chamber 3 is made of a high-temperature resistant material, which is selected from at least one of quartz, corundum, and stainless steel. As an example, in the following preferred embodiment of the invention, the reaction chamber 3 is made of quartz.

[0056] The material of the current collecting rod is selected from at least one of molybdenum rod, tungsten rod, and stainless steel rod. As an example, in the following preferred embodiment of the invention, the material of the current collecting rod is selected from molybdenum rod.

[0057] This invention provides a method for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system, employing the aforementioned apparatus, and specifically including the following steps:

[0058] S1. Mix the chloride molten salt, flux, and lunar soil / simulated lunar soil and place them in crucible 4. Place the crucible at the bottom of reaction chamber 3, heat to the drying temperature under a simulated lunar atmosphere, and maintain the temperature to remove residual moisture from the chloride molten salt. The flux (such as CaO) plays a co-solubilizing role during electrolysis, promoting the dissolution of iron-containing components through reaction with iron oxides in the lunar soil / simulated lunar soil. The relevant reaction equation is: x[Fe 2+ ][O 2- ]+(1-x)[Ca 2+ ][O 2- ]→[Fe 2+ ] x [Ca 2+ ] 1-x O;

[0059] S2. Continue heating to the electrodeposition temperature under a simulated lunar atmosphere and hold the temperature to dissolve the iron-containing components in the molten salt;

[0060] S3. Electrodeposition of iron-containing components in chloride molten salt is performed using a three-electrode system consisting of auxiliary electrode 5, working electrode 6, and reference electrode 7. Metallic iron is deposited on the working electrode 6, while oxygen is released on the auxiliary electrode 5. The potential is referenced to the working electrode 6 and the reference electrode 7, rather than the traditional reference between the auxiliary electrode 5 and the working electrode 6. This effectively avoids potential fluctuations caused by the polarization of the auxiliary electrode 5 during the electroreduction process. Under the control of the three electrodes, the working electrode undergoes a reduction reaction, reducing the iron-containing components in the lunar / simulated lunar soil to elemental iron. CaO and other components are separated and re-participate in the dissolution reaction. The auxiliary electrode 5 undergoes an oxidation reaction to produce oxygen. The relevant reaction equations are as follows:

[0061] [Fe 2+ ] x [Ca 2+ ] 1-x O+2xe - →xFe+(1-x)[Ca 2+ ][O 2- ]+x[O 2- ];

[0062] x[O 2- ]-2xe - →1 / 2O2.

[0063] The working electrode 6 is a graphite electrode.

[0064] The auxiliary electrode 5 is Fe. 50wt％ -Ni50wt％ Alloy electrode.

[0065] The reference electrode 7 is a high-purity graphite rod electrode.

[0066] In the following optional embodiments of the present invention, the chloride molten salt includes one or more of LiCl, KCl, NaCl, RbCl, CaCl2, SrCl2, and BaCl2. As an example, in the following preferred embodiments of the present invention, the chloride molten salt is selected as CaCl2.

[0067] In the following optional embodiments of the present invention, the co-solvent includes one or more of NaOH, CaO, MgO, and BaO. As an example, in the following preferred embodiments of the present invention, the co-solvent is selected as CaO.

[0068] In the following optional embodiments of the present invention, the chloride molten salt comprises 80-94 wt% (e.g., 84 wt%, 90 wt%, or 94 wt%), the co-solvent comprises 3-8 wt% (e.g., 3 wt%, 5 wt%, or 8 wt%), and the NEU-1a type simulated lunar soil comprises 3-8 wt% (e.g., 3 wt%, 5 wt%, or 8 wt%) by mass fraction.

[0069] In the following optional embodiments of the invention, the simulated lunar atmosphere includes an argon atmosphere and / or a nitrogen atmosphere. As an example, in the following preferred embodiments of the invention, the inert atmosphere is selected as an argon atmosphere.

[0070] In the following optional embodiments of the present invention, the specific drying operation steps are as follows: heating to 200-1000°C at a heating rate of 4°C / min, and holding at this temperature for 12 hours. As an example, in the following preferred embodiments of the present invention, the drying temperature is 300-500°C, more preferably 400°C.

[0071] In the following optional embodiments of the present invention, the specific operation steps of the electrodeposition are as follows: heating to 200-1000°C at a heating rate of 10°C / min, and holding at this temperature for 12 hours. As an example, in the following preferred embodiments of the present invention, the drying temperature is 800-900°C, more preferably 850°C.

[0072] In the following optional embodiments of the present invention, the electrodeposition voltage is -0.8 to -1.2V, and the time is 2-5 hours. As an example, in the following preferred embodiments of the present invention, the electrodeposition voltage is -0.8V, -1.0V, or -1.2V, and the time is 4 hours.

[0073] In the following optional embodiments of the present invention, the electrodeposition mechanism is a constant voltage mode and / or a pulsed electrodeposition mode. As an example, in the following preferred embodiment of the present invention, the electrodeposition mechanism is a constant voltage mode.

[0074] In the following optional embodiments of the present invention, in step S3, the obtained oxygen is purified, liquefied, and stored for later use.

[0075] The aforementioned device can be applied to the simultaneous preparation of metallic iron and oxygen in in-situ lunar resource utilization.

[0076] The above method can be applied to the separation of metallic components in lunar soil / simulated lunar soil.

[0077] All raw materials used in this invention were purchased from the market. It should be noted that, due to the difficulty in obtaining real lunar soil samples and the fact that this invention relates to the consumable use of lunar soil, simulated lunar soil NEU-1a was used as the experimental material in the embodiments. The composition of NEU-1a simulated lunar soil is shown in Table 1.

[0078] Table 1. Comparison of composition (wt%) between NEU-1a simulated lunar soil and real lunar soil

[0079]

[0080]

[0081] It should be clarified that actual lunar regolith is not a simple mixture of oxides, but exists in the form of complex mineral phases, mainly including: olivine (Mg,Fe)₂SiO₄, plagioclase CaAl₂Si₂O₈, and pyroxene (Ca,Fe,Mg)₂Si₂O₆, etc. To more realistically simulate the mineralogical characteristics of lunar regolith, the embodiments of this invention actually use a mixture of black volcanic slag and porous basalt to form a real complex mineral phase. Representing the simulated lunar regolith in oxide form is only for ease of understanding and does not represent the actual phases (see [link]). Figure 3 ).

[0082] In this invention, the " / " in "lunar soil / simulated lunar soil" means "or," meaning it can be either lunar soil or simulated lunar soil. Apollo14 and Apollo16 are real lunar soil, and the data comes from data in the paper, not from measurements made in this invention.

[0083] The technical solution of the present invention will be further illustrated by the following embodiments.

[0084] Figure 2 This is a schematic diagram of the process for preparing metallic iron and oxygen from lunar soil by molten salt electrodeposition according to the present invention.

[0085] Example 1

[0086] A method for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system, employing... Figure 1 The apparatus shown is used in the following steps:

[0087] S1. Mix CaCl2 molten salt, CaO and simulated lunar soil and load them into crucible 4. Place the crucible at the bottom of reaction chamber 3 and perform heating and electrodeposition operations under an argon atmosphere. The mixture contains 94 wt% CaCl2 molten salt, 3 wt% CaO and 3 wt% NEU-1a type simulated lunar soil.

[0088] S2. Place the device with the materials loaded in step S1 into a pit-type heating furnace and heat the molten salt system to 400°C and keep it at that temperature for 12 hours to remove residual moisture from the chloride molten salt. Then keep it at 850°C for 12 hours to allow the iron-containing components in the lunar soil to fully dissolve in the molten salt.

[0089] S3. Using a graphite electrode as the working electrode 6, with a mass fraction of Fe. 50wt％ -Ni 50wt％ Iron-nickel alloy was used as auxiliary electrode 5, and high-purity graphite rod was used as reference electrode 7. The three electrodes were inserted into the chloride molten salt obtained in step S2 for electrodeposition. During the electrodeposition process, the voltage between the working electrode 6 and the reference electrode 7 was controlled to be -0.8V, and the electrodeposition time was 4h. Four sets of parallel experiments under the same conditions were carried out for comparison. After electrodeposition, metallic iron was obtained from the working electrode 6, and oxygen was collected on the auxiliary electrode 5 and stored for later use.

[0090] Results Analysis: In the four parallel experiments during the S3 electrodeposition process, the average current efficiency of the working electrode was 81.8% (specifically 80.2%, 83.5%, 81.3%, and 82.3%), and the average current efficiency of oxygen generation at the auxiliary electrode was 62.8% (specifically 63.2%, 64.1%, 62.2%, and 61.5%). XRD analysis confirmed that all four products were elemental Fe phase (see [link to XRD analysis]). Figure 4 (A)), ICP analysis showed that all four products were Fe. 94.05wt％ -Mg 0.02wt％ -Si 3.28wt％ -Al 0.62wt％ Fe 94.03wt％ -Mg 0.03wt％ -Si 3.02wt％ -Al 0.43wt％ Fe 95.32wt％ -Mg 0.02wt％ -Si 2.21wt％ -Al 0.32wt％ and Fe 96.04wt％ -Mg 0.01wt％ -Si 1.24wt％ -Al 0.41wt％ The remainder is impurities (see average values). Figure 4 (B)); Compared with the extraction methods in patents CN114592215A and CN108505070A, the Fe content of the product in this embodiment is increased by 78-83wt%.

[0091] Example 2

[0092] A method for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system, employing... Figure 1 The apparatus shown is used in the following steps:

[0093] S1. Mix CaCl2 molten salt, CaO and simulated lunar soil and load them into crucible 4. Place the crucible at the bottom of reaction chamber 3 and perform heating and electrodeposition operations under an argon atmosphere. The mixture contains 90 wt% CaCl2 molten salt, 5 wt% CaO and 5 wt% NEU-1a type simulated lunar soil.

[0094] S2. Place the device with the materials loaded in step S1 into a pit-type heating furnace and heat the molten salt system to 400°C and keep it at that temperature for 12 hours to remove residual moisture from the chloride molten salt. Then keep it at 850°C for 12 hours to allow the iron-containing components in the lunar soil to fully dissolve in the molten salt.

[0095] S3. Using a graphite electrode as the working electrode 6, with a mass fraction of Fe. 50wt％ -Ni 50wt％ The iron-nickel alloy of the alloy is used as the auxiliary electrode 5, and a high-purity graphite rod is used as the reference electrode 7. The three electrodes are inserted into the chloride molten salt obtained in step S2 for electrodeposition. During the electrodeposition process, the voltage between the working electrode 6 and the reference electrode 7 is controlled to be -1.0V, and the electrodeposition time is 4h. Four sets of parallel experiments under the same conditions are carried out for comparison. After electrodeposition, metallic iron is obtained from the working electrode 6, and oxygen is collected on the auxiliary electrode 5 and stored for later use.

[0096] Results Analysis: In the four parallel experiments during the electrodeposition process in step S3, the average current efficiency of the working electrode was 78.8% (specifically 79.6%, 76.8%, 80.5%, and 78.3%), and the average current efficiency of oxygen generation at the auxiliary electrode was 57.7% (specifically 60.5%, 56.3%, 57.8%, and 56.2%). XRD analysis confirmed that all four products were elemental Fe phase (see [link to XRD analysis]). Figure 5 (A)), ICP analysis showed that all four products were Fe. 93.12wt％ -Mg 0.02wt％ -Si 3.82wt％ -Al 0.81wt％ Fe 93.89wt％ -Mg 0.04wt％ -Si 4.03wt％ -Al 0.72wt％ Fe 92.03wt％ -Mg 0.05wt％ -Si 4.02wt％ -Al 0.72wt％ and Fe 93.65wt％ -Mg 0.04wt％ -Si 2.52wt％-Al 0.87wt％ The remainder is impurities (see Figure 5 (B)); Compared with the extraction methods in patents CN114592215A and CN108505070A, the Fe content of the product in this embodiment is increased by 76-81 wt%.

[0097] Example 3

[0098] A method for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system, employing... Figure 1 The apparatus shown is used in the following steps:

[0099] S1. Mix CaCl2 molten salt, CaO and simulated lunar soil and load them into crucible 4. Place the crucible at the bottom of reaction chamber 3 and perform heating and electrodeposition operations under an argon atmosphere. The mixture contains 84 wt% CaCl2 molten salt, 8 wt% CaO and 8 wt% NEU-1a type simulated lunar soil.

[0100] S2. Place the device with the materials loaded in step S1 into a pit-type heating furnace and heat the molten salt system to 400°C and keep it at that temperature for 12 hours to remove residual moisture from the chloride molten salt. Then keep it at 850°C for 12 hours to allow the iron-containing components in the lunar soil to fully dissolve in the molten salt.

[0101] S3. Using a graphite electrode as the working electrode 6, with a mass fraction of Fe. 50wt％ -Ni 50wt％ Iron-nickel alloy was used as auxiliary electrode 5, and high-purity graphite rod was used as reference electrode 7. The three electrodes were inserted into the chloride molten salt obtained in step S2 for electrodeposition. During the electrodeposition process, the voltage between the working electrode 6 and the reference electrode 7 was controlled to be -1.2V, and the electrodeposition time was 4h. Four sets of parallel experiments under the same conditions were carried out for comparison. After electrodeposition, metallic iron was obtained from the working electrode 6, and oxygen was collected on the auxiliary electrode 5 and stored for later use.

[0102] Results Analysis: In the four parallel experiments during the S3 electrodeposition process, the average current efficiency of the working electrode was 71.6% (specifically 70.2%, 72.4%, 71.4%, and 72.4%), and the average current efficiency of oxygen generation at the auxiliary electrode was 55.7% (specifically 57.3%, 53.4%, 55.8%, and 56.2%). XRD analysis confirmed that all four products were elemental Fe phase (see [link to XRD analysis]). Figure 6 (A)), ICP analysis showed that all four products were Fe. 93.04wt％ -Mg 0.03wt％ -Si 4.04wt％ -Al 0.74wt％ Fe 93.32wt％ -Mg 0.06wt％ -Si 4.65wt％ -Al0.82wt％ Fe 91.08wt％ -Mg 0.04wt％ -Si 5.31wt％ -Al 0.73wt％ and Fe 92.35wt％ -Mg 0.04wt％ -Si 5.01wt％ -Al 0.72wt％ The remainder is impurities (see average values). Figure 6 (B)); Compared with the extraction methods in patents CN114592215A and CN108505070A, the Fe content of the product in this embodiment is increased by 75-80wt%.

[0103] Figure 7 The reduction voltages of different metal oxides in molten salt at 500-1000℃ were theoretically calculated using the formula E = ΔG / (-nF), where ΔG is the Gibbs free energy change (calculated using the thermodynamic software HSC); n is the number of electrons transferred in the reaction (mol); and F is the Faraday constant (96,485 C / mol). Based on thermodynamic calculations, it can be demonstrated that the reduction potential of iron ions is significantly different from that of other coexisting metal ions. Utilizing this potential difference, highly selective reduction of iron can be achieved within a specific potential window.

[0104] Comparative Example 1

[0105] Same as Example 1, except that the voltage in step S3 is adjusted to -2.0V to obtain the product on the surface of the working electrode.

[0106] Results analysis: ICP composition analysis showed that the product mainly consisted of 26.03 wt% Fe, 3.56 wt% Mg, 36.82 wt% Si and 30.28 wt% Al, with the remainder being impurities; compared with the product composition of Example 1, the iron content decreased by 68.83 wt%, confirming the effectiveness of potential control.

[0107] Comparative Example 2

[0108] Same as in Example 1, except that in step S3, the electrode is set as a graphite electrode as the working electrode 6, with a mass fraction of Fe. 50wt％ -Ni 50wt％ The iron-nickel alloy is used as the auxiliary electrode 5, and no reference electrode is set; the product is obtained on the surface of the working electrode.

[0109] Results analysis: ICP composition analysis showed that the product mainly consisted of 78.56 wt% Fe, 3.24 wt% Mg, 8.62 wt% Si and 7.83 wt% Al, with the remainder being impurities. Compared with the product composition of Example 1, the iron content decreased by 16.3 wt%, confirming that the three-electrode device design is more conducive to potential control.

[0110] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An apparatus for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system, characterized in that, include: The threaded tube sealing structure (1) has a through hole (1-2) at the top for placing the electrode and is connected to the reaction chamber sealing cover (8) by a thread (1-1); Gas inlet and outlet structure (2) is used to introduce a simulated lunar atmosphere; The reaction chamber (3) is connected to the reaction chamber sealing cover (8) by a thread (8-1); The crucible (4) is placed at the bottom of the reaction chamber (3); The three-electrode system includes an auxiliary electrode (5), a working electrode (6), and a reference electrode (7). Each electrode consists of a current collecting rod and an electrode head, which are inserted into the reaction chamber (3) through the through holes (1-2).

2. The apparatus according to claim 1, characterized in that, The reaction chamber (3) is made of a high-temperature resistant material, which is selected from at least one of quartz, corundum, and stainless steel; and / or, The material of the current collecting rod is selected from at least one of molybdenum rod, tungsten rod, and stainless steel rod; and / or, The working electrode (6) is a graphite electrode; and / or, The auxiliary electrode (5) is an Fe-Ni alloy electrode; and / or, The reference electrode (7) is a high-purity graphite rod electrode.

3. A method for preparing metallic iron and oxygen by electrodeposition of lunar soil using a three-electrode molten salt system, characterized in that, The device described in any one of claims 1-2 is used to implement this, specifically including the following steps: S1. Mix the chloride molten salt, flux and lunar soil / simulated lunar soil and put them into a crucible (4). Heat the crucible to the drying temperature under a simulated lunar atmosphere and keep it warm to remove moisture. S2. Continue heating to the electrodeposition temperature under a simulated lunar atmosphere and hold the temperature to dissolve the iron-containing components in the molten salt; S3. Electrodeposition is performed using a three-electrode system, depositing metallic iron on the working electrode (6) and releasing oxygen on the auxiliary electrode (5).

4. The method according to claim 3, characterized in that, The chloride molten salt includes one or more of LiCl, KCl, NaCl, RbCl, CaCl2, SrCl2, and BaCl2; and / or, The co-solvent includes one or more of NaOH, CaO, MgO, and BaO.

5. The method according to claim 3, characterized in that, The chloride molten salt comprises 80-94 wt% by mass, the co-solvent comprises 3-10 wt% by mass, and the lunar soil / simulated lunar soil comprises 3-10 wt% by mass.

6. The method according to claim 3, characterized in that, The simulated lunar atmosphere includes an argon atmosphere and / or a nitrogen atmosphere.

7. The method according to claim 3, characterized in that, The specific drying operation steps are as follows: heating to 300-500℃ at a rate of 4℃ / min, and maintaining this temperature for 12 hours; and / or, The specific steps for heating to the electrodeposition temperature and holding at that temperature are as follows: heat to 800-900℃ at a heating rate of 10℃ / min, and hold at that temperature for 12 hours.

8. The method according to claim 3, characterized in that, The electrodeposition voltage is -0.8 to -1.2 V, and the time is 2-5 hours; and / or, The electrodeposition is performed in a constant voltage mode and / or a pulsed electrodeposition mode.

9. The application of the apparatus as described in any one of claims 1-2 in the simultaneous preparation of metallic iron and oxygen in in-situ lunar resource utilization.

10. The application of the method as described in any one of claims 3-8 in the separation of metallic components in lunar soil / simulated lunar soil.

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