Method for extracting oxygen and metal from lunar soil

Abstract

A method for extracting oxygen and metal from lunar-based mineral resources comprises the following steps: in a vacuum / inert gas atmosphere, lunar soil which is not subjected to mineral separation treatment is directly contained in a conductive current collector device and serves as a working cathode, and an inert oxygen evolution anode and electrolyte are matched to form a molten salt electrolytic bath; after the electrolysis reactor is heated to a preset operation temperature, electrifying electrolysis is carried out under the driving force of an external power supply, and oxygen is separated out by an anode and collected by a gas collecting device; after a preset electrolysis mechanism and electrolysis time, the cathode current collector is recycled from the electrolytic bath, and a metal product is obtained; and a new cathode current collector is replaced to realize continuous process operation. A traditional process for extracting oxygen and metal from lunar soil usually only focuses on preparation of metal or oxygen, and the oxygen and the metal cannot be prepared at the same time. According to the method, the lunar soil composite oxide raw material is subjected to solid-phase electrochemical reduction, the aim of synchronously producing oxygen and metal is achieved, and a new short-process metallurgical process route for preparing metal and oxygen through direct electrolysis of lunar soil without mineral separation treatment is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy and relates to a method for extracting oxygen and metals from lunar-based mineral resources. Background Art

[0002] In the 21st century, with the advancement of human science and technology and a deeper understanding of the value of the moon, represented by my country's "International Lunar Research Station", the United States' "Artemis Lunar Exploration Program" and Europe's "Moon Village Program", human lunar exploration activities have gradually shifted from understanding the moon to a new stage where both understanding and utilization are given equal importance. In the new stage of utilizing the moon, the in-situ smelting process of lunar soil resources and the in-situ construction of the lunar base will become one of the key technologies for the construction and operation of the lunar research station, and will provide important technical support for the construction and operation of the lunar research station and the lunar base.

[0003] There is a weathering layer composed of rock debris on the lunar surface - lunar soil, with a particle size of less than 1 cm. The average thickness of lunar soil in the lunar highland geomorphic unit is 10m, and the average thickness in the lunar sea area is 4m. The main chemical components of lunar soil are a variety of composite metal oxides, which can be used as an important raw material for the preparation of oxygen and metals in the lunar surface smelting process. The methods that have been developed to extract metals and oxygen from lunar soil are mainly divided into four categories: carbon thermal reduction, hydrogen reduction, electrolysis and vacuum thermal decomposition.

[0004] The carbon thermal reduction method can reduce the metal oxides in the lunar soil at above 1550°C, and the products are Fe and a small amount of Si. H2 can reduce the Fe oxides in the lunar soil to Fe. These two methods can reduce the easily reduced Fe in the lunar soil, but cannot reduce other metal oxides that are not easily reduced. And both methods require a reducing agent, and the loss of the reducing agent needs to be replenished from the earth. The electrolysis method uses electrons as a reducing agent to electrically separate the metal oxides that are easier to separate in the lunar soil composite oxide ore to produce oxygen and metals (alloys). The electrolysis process has a series of difficulties and challenges such as high operating temperature, corrosion of electrode materials and reactor refractory materials, and stable service. The vacuum thermal decomposition method can directly decompose the lunar soil oxides into oxygen and low-valent metal oxides. This method has high energy consumption and the problem of separating the oxygen product from the low-valent metal oxide vapor phase needs to be solved.

[0005] The development of short-process and high-efficiency lunar soil resource separation / extraction / purification / storage technology is a strategic requirement for the future large-scale exploitation and utilization of various lunar soil mineral resources on the lunar surface and the construction of lunar scientific research stations. Electrons, as a reductant with adjustable activity, can be stably supplied through lunar surface solar power stations or nuclear power sources. Using electrons as a reductant, the lunar soil raw materials can be directly separated into metals and oxygen through a one-step electrolysis method. Summary of the invention

[0006] In response to the various process challenges and shortcomings in the existing preparation of metals and oxygen from lunar soil or lunar soil simulation samples, the present invention provides a method for directly preparing oxygen and metals by electrochemical separation of solid-phase lunar soil oxide powder.

[0007] The present invention uses lunar soil containing major lunar surface mineral components such as feldspar [CaAl2Si2O8, NaAlSi3O8], pyroxene [FeSiO3, CaSiO3, MgSiO3], olivine [Fe2SiO4, Mg2SiO4] and ilmenite [FeTiO3] as a cathode, and adopts an inert oxygen evolution anode and a halide molten electrolyte to produce oxygen and alloys from the lunar soil oxide raw materials through an electrochemical metallurgical process, thereby achieving the purpose of in-situ use of lunar soil to efficiently prepare oxygen and metals.

[0008] The technical solution of the present invention is:

[0009] A method for extracting oxygen and metals from lunar soil minerals comprises the following steps:

[0010] (1) Under vacuum / inert gas atmosphere, lunar soil without any mineral processing is directly placed in a conductive current collector device and used as a working cathode, and an inert oxygen evolution anode and an electrolyte are matched to form a molten salt electrolytic cell; the inert anode material is metal platinum, metal iridium, platinum-rhodium alloy, nickel-iron alloy, nickel-copper-iron-aluminum alloy, calcium titanate, ruthenium titanate, nickel ferrite, niobium titanate, etc.

[0011] (2) After the electrolytic reactor is heated to a predetermined operating temperature, electrolysis is performed under the driving force of an external power source, and oxygen is precipitated at the anode and collected by a gas collecting device;

[0012] (3) After a predetermined electrolysis mechanism and electrolysis time, the cathode current collector is recovered from the electrolytic cell to obtain a metal product; and a new cathode current collector is replaced to achieve continuous process operation;

[0013] (4) The collected oxygen is further purified and stored for use as an oxidant in the life support system and the launch system of the lunar transit station. At the same time, the metal products obtained by electrolysis are recovered from the cathode current collector device and cast into a mold to produce various products necessary for lunar construction.

[0014] In an argon atmosphere, the metal oxide components that undergo decomposition reactions in the lunar soil or lunar soil simulation sample during electrolysis are mainly silicon oxide, iron oxide, titanium oxide and aluminum oxide. The reaction equation involved is:

[0015] (1)SiO2→Si+O2 [1]

[0016] (2) TiO2→Ti+O2 [2]

[0017] (3)FeO→Fe+O2 [3]

[0018] (4)Fe2O3→Fe+O2 [4]

[0019] (5)Al2O3→Al+O2 [5] The general reaction formula involved in the electrolysis process is expressed as: MO x (dissolved)→M(s)+x / 2O2(g) [6]

[0020] Furthermore, the halide electrolyte described in the above step (1) includes one or more mixed molten salts of chlorides (LiCl, KCl, NaCl, RbCl, CaCl2, SrCl2, BaCl2, etc.), fluorides (LiF, NaF, KF, CaF2, RbF, BaF2, etc.), bromides (LiBr, NaBr, KBr, RbBr, BaBr2, etc.), and iodides (LiI, NaI, KI, RbI2, etc.).

[0021] Furthermore, in step (1), the inert atmosphere is argon atmosphere, nitrogen atmosphere, or hydrogen-argon mixed atmosphere.

[0022] Furthermore, in step (1), the vacuum degree of the vacuum atmosphere is 10 -9 ~10 -11 Pa.

[0023] Furthermore, in step (1), the cathode current collector device is made of stainless steel, metal nickel, metal molybdenum, or metal titanium.

[0024] Furthermore, in step (1), the mass ratio of the electrolyte to the lunar soil oxide in the cathode current collector is 100:1 to 5:1.

[0025] Furthermore, in step (2), the electrolysis mechanism is a constant voltage mode, a constant current mode, a pulse electrolysis mode or a combination of the above three electrolysis mechanisms.

[0026] Furthermore, in step (2), the electrolysis operation is performed in a temperature range of 300-600°C.

[0027] Furthermore, in step (2), oxygen is precipitated at the anode, and the mass of the collected oxygen accounts for 1 to 35 wt.% of the total mass of the lunar soil raw material; the anode Faraday current efficiency is 20% to 85%.

[0028] Furthermore, in step (3), the alloy chemical composition of the cathode product is as follows by mass percentage: Si 15-75wt.%, Ti 0.1-5.5wt.%, Fe 3-35wt.%, Al 3-50wt.%, and the cathode Faraday current efficiency is 20%-65%.

[0029] Beneficial effects of the present invention:

[0030] 1. With regard to the different lunar soil components corresponding to different landform units on the lunar surface, the method of the present invention has no restrictions on the lunar soil components and can be widely applied to the lunar soil corresponding to various geological units with development / research value.

[0031] 2. The present invention has low energy consumption and does not require complex and expensive equipment. The electrolysis reactor and the first batch of molten salt reagents need to be transported from the earth to the lunar surface, and then they can be recycled, which greatly reduces production costs.

[0032] 3. The process described in the present invention can realize the in-situ continuous production of oxygen and metals using lunar soil. The lunar soil raw materials do not require additional operating steps such as mineral processing and shaping, which greatly simplifies the operation difficulty.

[0033] 4. The traditional process of extracting oxygen and metals from lunar soil often only focuses on the preparation of metals or oxygen, and fails to achieve both. The present invention achieves the goal of simultaneous production of oxygen and metals through solid-phase electrochemical reduction of lunar soil composite oxide raw materials. The present invention realizes a new short-process metallurgical process route for directly electrolyzing lunar soil to prepare metals and oxygen without mineral processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the X-ray diffraction pattern of the metal product prepared from the lunar soil simulation sample in the present invention.

[0035] Figure 2 This is a gas chromatogram of the oxygen product collected by the present invention. DETAILED DESCRIPTION

[0036] The lunar soil simulation sample is a geochemical replica of the real lunar soil, and its chemical composition, mineral composition, particle size, mechanical strength, density, etc. are similar to the real lunar soil. Since the real lunar soil is very precious and scarce, the lunar soil simulation sample is used instead of the real lunar soil in the embodiments of the present invention.

[0037] The molten salt electrolyte used in the embodiment of the present invention can be recycled.

[0038] The chemical composition of the lunar soil or lunar soil simulation sample in the embodiment of the present invention is as follows by mass percentage: SiO240.6-48.7%, TiO2 0.47-8.6%, FeO 4.7-19.8%, CaO 10.3-15.8%, MgO 5.6-13.0%, Al2O312.5-28.0%, K2O 0.04-0.55%, Cr2O3 0.11-0.54%, MnO 0.12-0.41%, P2O50.05-0.51%, and the remainder is impurities.

[0039] Example 1

[0040] The chemical composition of the lunar soil simulation sample used is SiO2 42.20%, TiO2 7.80%, Al2O3 13.60%, FeO 15.3%, CaO 11.9%, MgO 7.8%, K2O 0.16%, Cr2O3 0.3%, MnO 0.20%, P2O5 0.05% by mass, and the remainder is impurities;

[0041] The lunar soil simulation sample was loaded into a stainless steel conductive current collector device as the cathode, a platinum sheet was used as an inert oxygen evolution anode, a 70% wt% LiCl-30wt.% KCl molten salt system was used as the electrolyte, and the mass ratio of the electrolyte to the lunar soil oxide in the cathode current collector was 60:1.

[0042] In an argon atmosphere, the electrolysis reactor was heated to 600°C, and an external power supply applied a voltage of 3.2V for electrolysis. Oxygen was precipitated at the anode and collected by a gas collection device.

[0043] After 6 hours of 3.2 V constant voltage electrolysis, the cathode current collector was recovered from the electrolytic cell and a metal product was obtained.

[0044] The chemical composition of the cathode alloy product obtained by electrolysis contains Si 32.46%, Ti 2.14%, Fe11.04%, Al 44.39% by mass, and the cathode current efficiency is 37.2%; the anode product is pure oxygen, and the anode current efficiency is 52.5%.

[0045] Example 2

[0046] The method is the same as in Example 1, except that:

[0047] (1) The chemical composition of the lunar soil simulation sample is SiO2 45.1%, TiO2 0.55%, Al2O3 22.3%, FeO 7%, CaO 15.1%, MgO 9.8%, K2O 0.1%, MnO 0.13%, P2O5 0.16% by mass, and the remainder is impurities;

[0048] (2) In 10 -9 Pa is carried out under vacuum atmosphere;

[0049] (3) Using metal iridium sheet as inert oxygen evolution anode;

[0050] (4) The chemical composition of the cathode alloy product obtained by electrolysis is Si 31.70%, Ti 0.16%, Fe 11.72%, and Al 54.21% by mass; the cathode current efficiency is 47.5%, and the anode current efficiency is 59.1%.

[0051] Example 3

[0052] (1) The chemical composition of the lunar soil simulation sample is SiO2 44.9%, TiO2 0.47%, Al2O3 28.0%, FeO 4.7%, CaO 15.7%, MgO 5.6%, K2O 0.23%, MnO 0.27%, P2O5 0.1% by mass, and the remainder is impurities;

[0053] (2) Constant current mode electrolysis with a current density of 0.6 A / cm 2 ;

[0054] (3) Performed under nitrogen atmosphere.

[0055] (4) The chemical composition of the cathode alloy product obtained by electrolysis is Si 32.46%, Ti 0.18%, Fe 0.76%, and Al 53.37% by mass; the cathode current efficiency is 53.2%, and the anode current efficiency is 59.6%.

[0056] Example 4

[0057] The method is the same as in Example 1, except that:

[0058] (1) The chemical composition of the lunar soil simulation sample is SiO2 48.1%, TiO2 1.7%, Al2O3 17.4%, FeO 10.4%, CaO 10.7%, MgO 9.4%, K2O 0.55%, MnO 0.14%, P2O5 0.51%, and the remainder is impurities.

[0059] (2) Electrolysis was performed in constant current mode with a current density of 0.5 A / cm 2 ;

[0060] (3) Using platinum-rhodium alloy as anode material;

[0061] (4) The chemical composition of the cathode alloy product obtained by electrolysis is Si 31.26%, Ti 0.16%, Fe 9.72%, and Al 55.22% by mass; the cathode current efficiency is 51.15%, and the anode current efficiency is 67.1%.

[0062] Example 5

[0063] The method is the same as in Example 1, except that:

[0064] (1) The chemical composition of the lunar soil simulation sample is SiO2 47.1%, TiO2 1%, Al2O3 13.4%, FeO 14.9%, CaO 10.3%, MgO 13.0%, K2O 1.85%, MnO 0.19%, P2O5 0.19% by mass, and the remainder is impurities;

[0065] (2) Under a hydrogen-argon mixed atmosphere;

[0066] (3) The cathode current collector is made of titanium metal;

[0067] (4) LiI molten salt was used as the electrolyte, and the mass ratio of the electrolyte to the lunar soil oxide in the cathode current collector was 80:1;

[0068] (5) The electrolysis temperature is set to 500°C;

[0069] (3) The chemical composition of the cathode alloy product obtained by electrolysis is Si 33.26%, Ti 0.19%, Fe 12.72%, and Al 52.22% by mass; the cathode current efficiency is 56.21%, and the anode current efficiency is 66.4%.

[0070] Example 6

[0071] The method is the same as in Example 1, except that:

[0072] (1) The chemical composition of the lunar soil simulation sample is SiO2 46.8%, TiO2 1.4%, Al2O3 14.6%, FeO 14.3%, CaO 10.8%, MgO 11.5%, K2O 0.21%, MnO 0.19%, P2O5 0.18% by mass, and the remainder is impurities;

[0073] (2) Using iron-nickel alloy as an inert anode;

[0074] (3) 43wt% KF-57wt% AlF3 molten salt was used as the electrolyte, and the mass ratio of the electrolyte to the lunar soil oxide in the current collector was 20:1;

[0075] (4) Electrolysis was performed in constant current mode with a current density of 0.6 A / cm 2 ;

[0076] (5) The chemical composition of the cathode alloy product obtained by electrolysis is Si 31.23%, Ti 0.17%, Fe 10.72%, and Al 53.23% by mass; the cathode current efficiency is 49.14%, and the anode current efficiency is 63.4%.

Claims

1. A method for extracting oxygen and metals from lunar soil minerals, characterized in that The steps include: (1) Under vacuum / inert gas atmosphere, the lunar soil without any mineral processing is directly placed in a conductive current collector device and used as a working cathode, and an inert oxygen evolution anode and an electrolyte are matched to form a molten salt electrolytic cell; the inert anode material is metal platinum, metal iridium, platinum-rhodium alloy, nickel-iron alloy, nickel-copper-iron-aluminum alloy, calcium titanate, ruthenium titanate, nickel ferrite, niobium titanate (2) After the electrolytic reactor is heated to a predetermined operating temperature, electrolysis is performed under the driving force of an external power source, and oxygen is precipitated at the anode and collected by a gas collecting device; (3) After a predetermined electrolysis mechanism and electrolysis time, the cathode current collector is recovered from the electrolytic cell to obtain a metal product; and a new cathode current collector is replaced to achieve continuous process operation; (4) The collected oxygen is further purified and stored for use as an oxidant in the life support system and the launch system of the lunar transit station. At the same time, the metal products obtained by electrolysis are recovered from the cathode current collector device and cast into a mold to produce various products necessary for lunar construction.

2. A method for extracting oxygen and metals from lunar soil minerals according to claim 1, characterized in that: In step (1), the halide electrolyte comprises a mixture of one or more molten salts of chloride, fluoride, bromide and iodide.

3. A method for extracting oxygen and metals from lunar soil minerals according to claim 2, characterized in that: In step (1), the chloride is LiCl, KCl, NaCl, RbCl, CaCl2, SrCl2, BaCl2; the fluoride is LiF, NaF, KF, CaF2, RbF, BaF2; the bromide is LiBr, NaBr, KBr, RbBr, BaBr2; the iodide is LiI, NaI, KI, RbI2.

4. The method for extracting oxygen and metals from lunar soil minerals according to claim 1, characterized in that: In step (1), the inert atmosphere is argon atmosphere, nitrogen atmosphere, or hydrogen-argon mixed atmosphere.

5. The method for extracting oxygen and metals from lunar soil minerals according to claim 1, characterized in that: In step (1), the vacuum degree of the vacuum atmosphere is 10-9 to 10-11 Pa.

6. A method for extracting oxygen and metals from lunar soil minerals according to claim 1, characterized in that In step (1), the cathode current collector device is made of stainless steel, metal nickel, metal Molybdenum, or metallic titanium.

7. The method for extracting oxygen and metals from lunar soil minerals according to claim 1, characterized in that In step (1), the mass ratio of the electrolyte to the lunar soil oxide in the cathode current collector is 100:1 to 5:

1.

8. The method for extracting oxygen and metals from lunar soil minerals according to claim 1, characterized in that: In step (2), the electrolysis mechanism is a constant voltage mode, a constant current mode, a pulse electrolysis mode Or a combination of the above three electrolysis mechanisms.

9. The method for extracting oxygen and metals from lunar soil minerals according to claim 1, characterized in that: In step (2), the electrolysis operation is carried out in a temperature range of 300-600°C.

10. The method for extracting oxygen and metals from lunar soil minerals according to claim 1, characterized in that The alloy chemical composition of the cathode product of the above step (3) is as follows by mass percentage: Si 15-75wt.%, Ti 0.1-5.5wt.%, Fe 3-35wt.%, Al 3-50wt.%.

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