Magnesium-lithium alloy preparation method based on ammonia dehydration and molten salt electrolysis coupling and magnesium-lithium alloy

Abstract

The invention discloses a magnesium-lithium alloy preparation method based on ammonia dehydration and molten salt electrolysis coupling, which comprises the following steps: putting bischofite and lithium chloride into a dehydration tank of an integrated reactor, and carrying out ammonia dehydration at 180-300 DEG C for 0.5-4 hours to obtain a solid material; and the solid material is conveyed to a fused salt electrolytic bath of the integrated reactor, direct current is introduced at the temperature of 450-550 DEG C for electrolytic treatment, and the magnesium-lithium alloy is prepared at a cathode through co-electro-deposition. The high-performance and high-purity magnesium-lithium alloy is directly obtained by forming a stable ammoniated ion cluster, optimizing the physical and chemical properties of the electrolyte, inhibiting side reaction, improving the current efficiency and accurately controlling the alloy phase composition and the microstructure. The problems that in the prior art, dependence on an inert gas protection system is caused, the technological process is fragmented, dehydration is difficult, and the alloy purity is low are solved.

Description

Technical Field

[0001] This invention relates to the field of landfill leachate treatment technology, and in particular to a method for preparing magnesium-lithium alloy based on ammonia dehydration coupled with molten salt electrolysis, and the magnesium-lithium alloy itself. Background Technology

[0002] Magnesium-lithium alloys are the lightest metallic structural materials in the world. Due to their excellent specific strength, specific stiffness, and good damping performance, they have irreplaceable application prospects in aerospace, military equipment, and 3C electronic products. Currently, the industrial production of magnesium-lithium alloys mainly adopts the "co-doping method." This process first produces metallic magnesium through the Pidgeon process or electrolysis, and metallic lithium through molten salt electrolysis. Then, the two metals are melted, stirred, and cast in a crucible protected by high temperature (usually above 700°C) and vacuum or inert atmosphere. However, this method has drawbacks such as high energy consumption, lithium loss, and uneven alloy structure.

[0003] Molten salt electrolysis is considered a promising alternative process that can directly produce alloys from salt in a single step. Using pre-dehydrated anhydrous magnesium chloride and anhydrous lithium chloride as raw materials, they are mixed in the desired proportions and placed in a sealed electrolytic cell. Under the protection of an inert gas (such as argon), the mixture is heated to 650-750°C to melt and form an electrolyte. Direct current is then applied, and a magnesium-lithium alloy is deposited at the cathode. Theoretically, the process is shorter and consumes less energy. However, the core bottleneck lies in the fact that anhydrous magnesium chloride is a prerequisite, and obtaining electrolytic-grade anhydrous magnesium chloride is the cornerstone of the entire process, a step that is extremely costly and difficult. A protective atmosphere is essential; to prevent moisture and oxygen in the air from damaging the molten salt and metal products, air must be completely isolated throughout the process. The entire electrolysis system must operate under an inert atmosphere, limiting equipment operability and increasing maintenance costs and energy consumption. Traditional thermal dehydration methods cannot fundamentally eliminate the hydrolysis reaction of magnesium chloride, introducing MgO impurities that reduce current efficiency and affect alloy purity. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a magnesium-lithium alloy preparation method based on ammonia dehydration coupled with molten salt electrolysis, so as to solve the problems of dependence on inert gas protection system, fragmented process flow, difficulty in dehydration and low alloy purity in the prior art.

[0005] This invention provides a method for preparing magnesium-lithium alloys based on the coupling of ammonia dehydration and molten salt electrolysis, the method comprising: S1. Place magnesium chloride and lithium chloride in the dehydration tank of the integrated reactor and dehydrate them by ammonia method at 180-300℃ for 0.5-4h to obtain solid material; S2. Solid materials are transported to the molten salt electrolysis cell of the integrated reactor and electrolyzed at 450-550℃ with direct current, and magnesium-lithium alloy is prepared by co-electrodeposition at the cathode.

[0006] The integrated reactor comprises a dehydration tank and a molten salt electrolytic cell, which can be arranged in a "top-bottom structure" or a "parallel structure," connected to the electrolytic cell via a screw conveyor or pneumatic conveyor. The electrolytic cell is a multi-stage cell or a bipolar electrode cell.

[0007] Preferably, the step of dehydrating magnesium chloride and lithium chloride with ammonia at 180-300°C for 0.5-4 hours specifically involves mixing magnesium chloride and lithium chloride and then dehydrating them with ammonia at 180-300°C for 0.5-4 hours, or dehydrating magnesium chloride and lithium chloride separately with ammonia at 180-300°C for 0.5-4 hours before mixing them.

[0008] The ammonia dehydration method can be achieved by passing magnesium chloride and lithium chloride into dry pure ammonia gas or a mixture of ammonia gas and inert gas. Alternatively, ammonium chloride solid can be added to magnesium chloride and lithium chloride and thoroughly ground and mixed. The ammonium chloride decomposes under heating to produce NH3 and HCl. The trace amount of HCl can further enhance the hydrolysis inhibition effect.

[0009] Preferably, in step S1, the molar ratio of magnesium to lithium in hydrated magnesium chloride and lithium chloride is 5-15:1.

[0010] Preferably, in step S2, the anode of the molten salt electrolytic cell is selected from graphite, metal oxide ceramics, or metal ceramics.

[0011] Preferably, in step S2, the cathode of the molten salt electrolytic cell is selected from one of the following: low-melting-point magnesium-lithium alloy, solid magnesium, tin, molybdenum, copper, stainless steel, tungsten, and nickel.

[0012] Preferably, in step S2, the cathode of the molten salt electrolytic cell is selected from solid magnesium or molybdenum.

[0013] Preferably, in step S2, the cathode current density is controlled to be 0.5-2.5 A / cm² during the electrolysis process. 2 .

[0014] Preferably, step S2 further includes using an organic amine as a coupling agent, one or more of KCl, NaCl, CsCl, RbCl, and fluoride salts as a co-solvent, and Mg(BH4)2 as an overpotential reducing agent for magnesium deposition. The co-solvent can enhance metal aggregation and reduce secondary dispersion.

[0015] The present invention also provides a magnesium-lithium alloy, which is prepared by the preparation method described above.

[0016] Preferably, the magnesium-lithium alloy is an α-phase, β-phase, or α+β dual-phase magnesium-lithium alloy, and its lithium content is 5-16 wt%.

[0017] The present invention has the following beneficial effects: 1. This invention provides a method for preparing magnesium-lithium alloys based on the coupling of ammonia dehydration and molten salt electrolysis. By forming stable ammonia ion clusters, the physicochemical properties of the electrolyte are optimized, side reactions are suppressed, current efficiency is improved, and precise control over the alloy phase composition and microstructure is achieved, directly obtaining high-performance magnesium-lithium alloys. The magnesium oxide impurity content in the product can be controlled at <100ppm, far lower than that of traditional processes (>1000ppm). The alloy composition is uniform, the microstructure is fine, and the mechanical properties are excellent. This invention innovatively couples the dehydration and electrolysis processes into one system. The "ammonia" introduced in the dehydration stage is not an impurity that needs to be completely removed, but continues to provide a chemically protective environment against hydrolysis in the electrolysis stage, thus avoiding the occurrence of hydrolysis reactions in principle. The dehydration process is carried out at low temperatures, and the electrolysis process is carried out at moderate temperatures. In addition, the thermal energy within the system is utilized synergistically. Compared with the "co-doping method" or "traditional high-temperature electrolysis method", the overall energy consumption is expected to be reduced by 30%-45%, achieving low-temperature, high-efficiency, and simplified deep dehydration.

[0018] 2. In the ammonia dehydration process at 150-250℃, ammonia molecules attack hydrated magnesium ions, gradually replacing coordinated water molecules to form stable crystalline ammonia complexes, such as MgCl2·2NH3. This reaction converts strongly bound water into coordinated ammonia and free water in the complex, and the reaction energy barrier is much lower than that of directly breaking the Mg-OH2 bond.

[0019] 3. During electrolysis, the formed ammonium complex structure is stable. It only gradually decomposes and releases ammonia gas when the temperature reaches 450-550℃, leaving behind active anhydrous magnesium chloride. This effectively bypasses the critical hydrolysis temperature range that is necessary for direct thermal dehydration of magnesium chloride. In the electrolysis process of this invention, the molten electrolyte is not a simple mixture of MgCl2-LiCl ions, but contains a large amount of [Mg(NH2)x]. 2+ (x=1,2) A complex system of magnesium ammonium ion clusters, whose roles are: Shielding and stabilization: The NH3 molecule acts as an electron donor, coordinating with Mg. 2 The surrounding environment forms spatial and electronic shielding, significantly reducing Mg levels. 2 The + Lewis acidity makes it difficult for it to attract and capture residual water molecules or OH groups. - O in 2- This fundamentally inhibits the occurrence of hydrolysis.

[0020] Altering deposition kinetics: This ion cluster may alter the interface double layer structure and energy barrier of magnesium ions during cathode discharge, potentially reducing the overpotential for magnesium nucleation and making the co-deposition of magnesium and lithium more synchronous and uniform, which is beneficial for forming alloys with uniform composition.

[0021] Maintaining molten salt stability: The presence of this ion cluster is equivalent to establishing a "buffer system" in the molten salt, which can capture and neutralize H+ that may be introduced by trace amounts of moisture. + or OH - This maintains the chemical stability of the entire electrolyte.

[0022] 4. Direct use of inexpensive magnesium chloride eliminates the need for expensive deep dehydration units, reducing raw material costs by 30%-50%; the inherent chemical protection environment created by ammonia dehydration allows the electrolysis process to operate stably under normal atmospheric pressure, eliminating the need for complex vacuum or inert gas protection systems, thus reducing equipment investment and operating costs.

[0023] 5. No HCl corrosive gas emissions, ammonia gas achieves closed-loop circulation within the system, and chlorine gas generated at the anode can be recovered as a byproduct. Attached Figure Description

[0024] Figure 1 A process flow diagram of a magnesium-lithium alloy preparation method based on ammonia dehydration coupled with molten salt electrolysis is provided for an embodiment of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "top surface," "bottom surface," "inner," "outer," "inner side," and "outer side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. Where the terms "first," "second," and "third" are used for descriptive purposes and to distinguish technical features, they should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the sequential relationship of the indicated technical features.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The embodiments of this invention will now be described according to its overall structure.

[0029] Figure 1 A process flow diagram of a magnesium-lithium alloy preparation method based on ammonia dehydration coupled with molten salt electrolysis is provided for embodiments of the present invention. (See attached diagram.) Figure 1 This invention provides a method for preparing magnesium-lithium alloys based on ammonia dehydration coupled with molten salt electrolysis, the method comprising: S1. Place magnesium chloride and lithium chloride in the dehydration tank of the integrated reactor and dehydrate them by ammonia method at 180-300℃ for 0.5-4h to obtain solid material; S2. Solid materials are transported to the molten salt electrolysis cell of the integrated reactor and electrolyzed at 450-550℃ with direct current, and magnesium-lithium alloy is prepared by co-electrodeposition at the cathode.

[0030] The integrated reactor comprises a dehydration tank and a molten salt electrolytic cell, which can be arranged in a "top-bottom structure" or a "parallel structure," connected to the electrolytic cell via a screw conveyor or pneumatic conveyor. The electrolytic cell is a multi-stage cell or a bipolar electrode cell.

[0031] In a preferred embodiment, the process of dehydrating magnesium chloride and lithium chloride with ammonia at 180-300°C for 0.5-4 hours specifically involves mixing magnesium chloride and lithium chloride and then dehydrating them with ammonia at 180-300°C for 0.5-4 hours, or dehydrating magnesium chloride and lithium chloride separately with ammonia at 180-300°C for 0.5-4 hours before mixing them.

[0032] The ammonia dehydration method can be achieved by passing magnesium chloride and lithium chloride into dry pure ammonia gas or a mixture of ammonia gas and inert gas. Alternatively, ammonium chloride solid can be added to magnesium chloride and lithium chloride and thoroughly ground and mixed. The ammonium chloride decomposes under heating to produce NH3 and HCl. The trace amount of HCl can further enhance the hydrolysis inhibition effect.

[0033] In a preferred embodiment, in step S1, the molar ratio of magnesium to lithium in hydrated magnesium chloride and lithium chloride is 5-15:1.

[0034] In a preferred embodiment, in step S2, the anode of the molten salt electrolytic cell is selected from graphite, metal oxide ceramics, or cermet.

[0035] In a preferred embodiment, in step S2, the cathode of the molten salt electrolytic cell is selected from one of the following: low-melting-point magnesium-lithium alloy, solid magnesium, tin, molybdenum, copper, stainless steel, tungsten, and nickel.

[0036] In a preferred embodiment, in step S2, the cathode of the molten salt electrolytic cell is selected from solid magnesium or molybdenum.

[0037] In a preferred embodiment, in step S2, the cathode current density is controlled to be 0.5-2.5 A / cm² during the electrolysis process. 2 .

[0038] In a preferred embodiment, step S2 further includes using an organic amine as a coupling agent, one or more of KCl, NaCl, CsCl, RbCl, and fluoride salts as a co-solvent, and Mg(BH4)2 as an overpotential reducing agent for magnesium deposition. The co-solvent can enhance metal aggregation and reduce secondary dispersion.

[0039] This invention also provides a magnesium-lithium alloy, which is prepared by the preparation method described above.

[0040] Example 1: Preparation of low-lithium-content α-phase magnesium-lithium alloy Raw materials: Magnesium chloride hexahydrate (MgCl2·6H2O) and anhydrous lithium chloride are mixed at a Mg:Li molar ratio of 15:1.

[0041] Dehydration: At 180℃, a mixture of dry NH3 and N2 at a flow rate of 100 mL / min and a flow rate of 200 mL / min was introduced, with a gas ratio of 1:2, and the mixture was treated for 2.5 h.

[0042] Electrolysis: The material is transferred to an electrolysis zone at 500℃, using graphite as the anode and a stainless steel rod as the cathode. The cathode current density is controlled at 1.0 A / cm². 2 Electrolysis for 120 minutes.

[0043] Results: A silvery-white α-phase magnesium-lithium alloy ingot was obtained, with a lithium content of approximately 5.2 wt% and a density of 1.39 g / cm³. 3 Its hardness (HV) is 55.

[0044] Example 2: Preparation of α+β dual-phase magnesium-lithium alloy with moderate lithium content Raw materials: MgCl2·6H2O and LiCl are mixed at a Mg:Li molar ratio of 10:1.

[0045] Dehydration: Pure dry NH3 was introduced at 220℃ (flow rate 150 mL / min) for 1.5 h.

[0046] Electrolysis: Electrolyze at 480℃ with the cathode potential controlled at -2.5V (vs. Ag / AgCl reference) for 90 min.

[0047] Results: An α+β dual-phase magnesium-lithium alloy was obtained, with a lithium content of approximately 10.8 wt% and a density of 1.52 g / cm³. 3 It has good plasticity.

[0048] Example 3: Preparation of high-lithium-content β-phase magnesium-lithium alloy Raw materials: MgCl2·6H2O and LiCl are mixed at a Mg:Li molar ratio of 6:1.

[0049] Dehydration: At 200℃, dry NH3 and Ar were introduced at a flow rate of 150 mL / min and a flow rate of 150 mL / min, with the NH3 / Ar mixture ratio of 1:1, and the treatment lasted for 2 hours.

[0050] Electrolysis: At 460℃, the cathode current density is 1.8 A / cm². 2 Electrolysis for 60 minutes.

[0051] Results: A magnesium-lithium alloy dominated by the β phase was obtained, with a lithium content of approximately 15.5 wt% and a density of 1.38 g / cm³. 3 Ultralight.

[0052] Example 4: Using ammonium chloride as a dehydrating agent Raw materials: Mix MgCl2·6H2O and LiCl at a ratio of Mg:Li = 10:1, then add NH4Cl solid in a molar amount equivalent to 1.2 times the total amount of magnesium, and grind and mix thoroughly.

[0053] Dehydration: Heating at 250°C in static air for 2 hours. NH4Cl decomposition provides an atmosphere of NH3 and HCl.

[0054] Electrolysis: Electrolysis was carried out at 500°C, with other parameters the same as in Example 2.

[0055] Results: A magnesium-lithium alloy with a lithium content of approximately 11.0 wt% and a density of 1.50 g / cm³ was successfully prepared. 3 The alloy properties are comparable to those of Example 2 with ammonia.

[0056] Example 5: Adding flux to the electrolyte Raw materials: MgCl2·6H2O, LiCl and KCl are mixed in a final molten salt composition of 45wt% MgCl2, 40wt% LiCl and 15wt% KCl.

[0057] Dehydration: The steps are the same as in Example 2.

[0058] Electrolysis: The steps are the same as in Example 2.

[0059] Results: The electrolysis temperature can be reduced to 450℃, the electrolyte can still maintain good fluidity, the current efficiency is improved by about 5%, and the alloy composition is more uniform.

[0060] Example 6: Investigating the effect of dehydration temperature The same formulation as in Example 2, but with dehydration temperatures of 150°C, 300°C, and 350°C respectively.

[0061] Results: Dehydration was incomplete at 150℃, with bubbles from water electrolysis appearing in the initial stage of electrolysis; the effect was good at 300℃, with almost no hydrolysis; at 350℃, some ammonia complexes decomposed prematurely, with slight hydrolysis. This indicates that the optimal dehydration window is 180-300℃.

[0062] Example 7: Investigating the effect of electrolysis temperature The same formulation and dehydration conditions as in Example 2 were used, with electrolysis temperatures of 430°C, 500°C, and 580°C, respectively.

[0063] Results: As shown in Table 1, the electrolyte viscosity was slightly higher and metal aggregation was slightly worse at 430℃; the effect was best at 500℃; metal volatilization loss increased and current efficiency decreased at 580℃. This proves that the optimal electrolysis window is 450-550℃.

[0064] Table 1 Effect of electrolysis temperature on performance temperature Electrolyte viscosity (Pa·s) Metal volatilization loss (%) Remark 430℃ 120 0.5 The electrolyte has poor fluidity, the metal droplets aggregate slowly, and the cathode products are dispersed. 500℃ 25 1.0 The electrolyte has good fluidity and high metal aggregation efficiency. 580℃ 15 3.5 The electrolyte viscosity is very low, but the volatilization of lithium and magnesium is significantly amplified. Example 8: Comparative Experiment of Atmospheric Pressure and Inert Protection Under the same conditions as in Example 2, one group was carried out in air, and the other group was carried out under argon protection.

[0065] Results: The alloy composition, microstructure and properties obtained in the two sets of experiments were not significantly different from those of the alloy obtained in Example 2, proving that the present invention can indeed achieve stable electrolysis under normal atmospheric pressure.

[0066] Example 9: Tests with different cathode materials Under the same conditions as in Example 2, solid magnesium rods, molybdenum electrodes, and molybdenum electrodes were used as cathodes to test the alloy yield and the content of key impurities. Here, "O" refers to the total content of oxygen impurity elements in the alloy. The most important and harmful form of oxygen impurities is magnesium oxide (MgO) particles. The test results are shown in Table 2 below.

[0067] Table 2. Effect of cathode material on yield and impurity content Alloy yield (%) Content of key impurities in the alloy (ppm) Solid magnesium rod 95 O<80,Fe<20 molybdenum electrode 92 O<100, Mo<10 copper electrode 88 O>200, Cu>500 Results: Magnesium-lithium alloys were successfully prepared in all cases, with solid magnesium rods and molybdenum electrodes showing the best results. The alloys were easy to separate from the cathode.

[0068] Example 10: Continuous Feeding Experiment The system adopts a dual-reactor series system, with continuous feeding and discharging in the dehydration reactor, and the dehydrated material is continuously fed into the electrolytic cell by a screw feeder.

[0069] Results: The system can run stably for more than 8 hours and continuously produce magnesium-lithium alloys with stable composition, proving that this technical solution is suitable for continuous industrial production.

[0070] In summary, this invention provides a magnesium-lithium alloy preparation method based on the coupling of ammonia dehydration and molten salt electrolysis. By forming stable ammonium ion clusters, optimizing the physicochemical properties of the electrolyte, suppressing side reactions, improving current efficiency, and achieving precise control over the alloy phase composition and microstructure, high-performance magnesium-lithium alloys are directly obtained. The magnesium oxide impurity content in the product can be controlled at <100ppm, far lower than that of traditional processes (>1000ppm). The alloy composition is uniform, the microstructure is fine, and the mechanical properties are excellent. This invention innovatively couples the dehydration and electrolysis processes into one system. The "ammonia" introduced in the dehydration stage is not an impurity that needs to be completely removed, but continues to provide a chemically protective environment against hydrolysis in the electrolysis stage, thus avoiding hydrolysis reactions in principle. The dehydration process is carried out at low temperatures, and the electrolysis process is carried out at moderate temperatures. In addition, the system's thermal energy is utilized synergistically. Compared with the "co-doping method" or "traditional high-temperature electrolysis method," the overall energy consumption is expected to be reduced by 30%-45%, achieving low-temperature, high-efficiency, and simplified deep dehydration.

[0071] In the ammonia dehydration process at 150-250℃, ammonia molecules attack hydrated magnesium ions, gradually replacing coordinated water molecules to form stable crystalline ammonia complexes, such as MgCl2·2NH3. This reaction converts strongly bound water into coordinated ammonia and free water in the complex, and the reaction energy barrier is much lower than that of directly breaking the Mg-OH2 bond.

[0072] During electrolysis, the formed ammonium complex is structurally stable and only gradually decomposes to release ammonia gas when the temperature reaches 450-550℃, leaving behind active anhydrous magnesium chloride. This effectively bypasses the critical hydrolysis temperature range that is necessary for direct thermal dehydration of magnesium chloride. In the electrolysis process of this invention, the molten electrolyte is not a simple mixture of MgCl2-LiCl ions, but contains a large amount of [Mg(NH2)x]. 2+ (x=1,2) A complex system of magnesium ammonia ion clusters. The functions of these ion clusters are: shielding and stabilization: NH3 molecules act as electron donors, coordinating with Mg. 2 The surrounding environment forms spatial and electronic shielding, significantly reducing Mg levels. 2 The + Lewis acidity makes it difficult for it to attract and capture residual water molecules or OH groups. - O in 2- This fundamentally inhibits the hydrolysis reaction. It alters deposition kinetics: the ion cluster may change the interfacial double-layer structure and energy barrier of magnesium ions at the cathode discharge interface, potentially reducing the magnesium nucleation overpotential and making the co-deposition of magnesium and lithium more synchronous and uniform, thus promoting the formation of alloys with homogeneous composition. It maintains molten salt stability: the presence of this ion cluster is equivalent to establishing a "buffer system" in the molten salt, capable of capturing and neutralizing H2O that may be introduced by trace amounts of moisture. + or OH - This maintains the chemical stability of the entire electrolyte.

[0073] This invention directly uses inexpensive magnesium chloride, eliminating the need for expensive deep dehydration units and reducing raw material costs by 30%-50%. The inherent chemical protection environment created by ammonia dehydration allows the electrolysis process to operate stably under normal atmospheric pressure, eliminating the need for complex vacuum or inert gas protection systems and reducing equipment investment and operating costs.

[0074] The method of this invention produces no corrosive HCl gas emissions, achieves closed-loop circulation of ammonia within the system, and allows chlorine generated at the anode to be recovered as a byproduct.

[0075] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for preparing magnesium-lithium alloys based on the coupling of ammonia dehydration and molten salt electrolysis, characterized in that, The method includes: S1. Place magnesium chloride and lithium chloride in the dehydration tank of the integrated reactor and dehydrate them by ammonia method at 180-300℃ for 0.5-4h to obtain solid material; S2. Solid materials are transported to the molten salt electrolysis cell of the integrated reactor and electrolyzed at 450-550℃ with direct current, and magnesium-lithium alloy is prepared by co-electrodeposition at the cathode.

2. The method for preparing magnesium-lithium alloy based on ammonia dehydration coupled with molten salt electrolysis according to claim 1, characterized in that, The process of dehydrating magnesium chloride and lithium chloride with ammonia at 180-300℃ for 0.5-4 hours specifically involves mixing magnesium chloride and lithium chloride and then dehydrating them with ammonia at 180-300℃ for 0.5-4 hours, or dehydrating magnesium chloride and lithium chloride separately with ammonia at 180-300℃ for 0.5-4 hours and then mixing them. The ammonia dehydration method can be achieved by passing magnesium chloride and lithium chloride into dry pure ammonia gas or a mixture of ammonia gas and inert gas, or by adding solid ammonium chloride to magnesium chloride and lithium chloride and grinding and mixing them thoroughly.

3. The method for preparing magnesium-lithium alloy based on ammonia dehydration coupled with molten salt electrolysis according to claim 1, characterized in that, In step S1, the molar ratio of magnesium to lithium in magnesium chloride and lithium chloride is 5-15:

1.

4. The method for preparing magnesium-lithium alloy based on ammonia dehydration coupled with molten salt electrolysis according to claim 1, characterized in that, In step S2, the anode of the molten salt electrolytic cell is selected from graphite, metal oxide ceramics, or metal ceramics.

5. The method for preparing magnesium-lithium alloy based on ammonia dehydration coupled with molten salt electrolysis according to claim 1, characterized in that, In step S2, the cathode of the molten salt electrolytic cell is selected from one of the following: low-melting-point magnesium-lithium alloy, solid magnesium, tin, molybdenum, copper, stainless steel, tungsten, and nickel.

6. The method for preparing magnesium-lithium alloy based on ammonia dehydration coupled with molten salt electrolysis according to claim 5, characterized in that, In step S2, the cathode of the molten salt electrolytic cell is selected from solid magnesium or molybdenum.

7. The method for preparing magnesium-lithium alloy based on ammonia dehydration coupled with molten salt electrolysis according to claim 1, characterized in that, In step S2, the cathode current density is controlled to be 0.5-2.5 A / cm during the electrolysis process. 2 .

8. The method for preparing magnesium-lithium alloy based on ammonia dehydration coupled with molten salt electrolysis according to claim 1, characterized in that, Step S2 further includes using an organic amine as a coupling agent, using one or more of KCl, NaCl, CsCl, RbCl, and fluoride salts as a co-solvent, and using Mg(BH4)2 as an overpotential reducing agent for magnesium deposition.

9. A magnesium-lithium alloy, characterized in that, The magnesium-lithium alloy is prepared by the preparation method described in any one of claims 1-8.

10. A magnesium-lithium alloy according to claim 9, wherein the magnesium-lithium alloy is an α-phase, β-phase, or α+β dual-phase magnesium-lithium alloy, and its lithium content is 5-16 wt%.

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