An apparatus and method for preparing metals by molten salt electroreduction

Abstract

This application discloses an apparatus and method for preparing metals by molten salt electroreduction, belonging to the field of molten salt electroreduction. It addresses the problems of high energy consumption and cost, and environmental impact, inherent in existing metal preparation processes. The apparatus includes a reactor, a conductor, a power source, a gas charging and discharging mechanism, and a sealing mechanism. The reactor is a barrel-shaped structure with a conductive bottom plate, insulated peripheral walls, and an open end. The reactor cavity is configured to sequentially lay the reactant and molten salt from bottom to top. The conductor is used to insert the molten salt. The reactor and conductor are located inside the sealing mechanism, while the power source is located outside the sealing mechanism. The positive terminal of the power source is electrically connected to the conductor, and the negative terminal is electrically connected to the bottom plate. The gas charging and discharging mechanism is configured to continuously charge the reactor with protective gas while simultaneously discharging waste gas. This application reduces the energy consumption and cost of metal preparation processes and is beneficial to environmental protection.

Description

Technical Field

[0001] This application relates to the field of molten salt electroreduction technology, and in particular to an apparatus and method for preparing metals by molten salt electroreduction. Background Technology

[0002] Traditional metal smelting processes play a crucial role in various sectors of national production and daily life. As a major steel producer, China's annual pig iron output exceeds 500 million tons. Currently, blast furnace ironmaking is the dominant technology in my country. Firstly, the blast furnace ironmaking process is complex, involving sintering, coking, and blast furnace refining, requiring significant energy and resource consumption, resulting in high costs. Secondly, blast furnace ironmaking consumes large quantities of coke as a reducing agent and raw material; moreover, the coking process not only consumes substantial amounts of non-renewable coal resources but also generates large quantities of CO2 and toxic gases. Finally, blast furnace ironmaking produces a large amount of slag. Summary of the Invention

[0003] This application provides an apparatus and method for preparing metals by molten salt electroreduction, which can solve the problems of high energy consumption and cost in existing metal preparation processes, and the negative impact on environmental protection.

[0004] To achieve the above objectives, the technical solution of this invention is as follows:

[0005] In a first aspect, embodiments of the present invention provide an apparatus for preparing metal by electroreduction of molten salt, comprising a reactor, a conductor, a power source, a gas charging and discharging mechanism, and a sealing mechanism; the reactor is a barrel with a conductive bottom plate, insulated peripheral walls, and an open end, the barrel cavity of the reactor being configured to sequentially lay the reactant and molten salt from bottom to top; the conductor is used to insert the molten salt; the reactor and the conductor are disposed inside the sealing mechanism, and the power source is disposed outside the sealing mechanism; the positive terminal of the power source is electrically connected to the conductor, and the negative terminal of the power source is electrically connected to the bottom plate; the gas charging and discharging mechanism is configured to continuously charge the reactor with protective gas while simultaneously discharging waste gas.

[0006] In conjunction with the first aspect, in one possible implementation, the reactor includes a conductive base plate and a first insulating cylinder disposed on the conductive base plate. The outer diameter of the conductive base plate is equal to or greater than the outer diameter of the first insulating cylinder.

[0007] In conjunction with the first aspect, in one possible implementation, the reactor includes a conductive barrel and a second insulating cylinder; the second insulating cylinder is inserted into the conductive barrel, and its bottom surface abuts against the inner bottom surface of the conductive barrel.

[0008] In conjunction with the first aspect, in one possible implementation, the apparatus for preparing metal by molten salt electroreduction further includes a first conductive rod; one end of the first conductive rod is electrically connected to a conductor, and the other end extends through the enclosed mechanism and is electrically connected to the positive terminal of the power supply.

[0009] Secondly, embodiments of the present invention provide a method for preparing metals by molten salt electroreduction, using the apparatus for preparing metals by molten salt electroreduction described above, comprising:

[0010] The reactor chamber is lined with the reactant and the molten salt from bottom to top.

[0011] After heating the reactor until the molten salt melts, the conductor is inserted into the molten salt.

[0012] Protective gas is continuously introduced into the reactor through the gas filling and discharging mechanism, while exhaust gas is discharged, and the power supply is turned on to perform molten salt electroreduction.

[0013] Once the reaction in the barrel cavity is complete, disconnect the power supply, pour out the molten salt material from the upper part of the barrel cavity, and remove the residue from the lower part.

[0014] Metal is obtained from the retained material.

[0015] In conjunction with the second aspect, in one possible implementation, obtaining the metal through the residue includes:

[0016] The residue was soaked in ultrapure water multiple times to obtain powdered metal.

[0017] In conjunction with the second aspect, in one possible implementation, obtaining the metal through the residue includes:

[0018] The residue is heated to the metal melting point to obtain liquid or bulk metal.

[0019] In conjunction with the second aspect, in one possible implementation, the molten salt substance is one or more of a chloride or a fluoride.

[0020] In conjunction with the second aspect, in one possible implementation, the reactant comprises a metal oxide and a conductive agent.

[0021] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0022] This invention provides an apparatus for preparing metals by molten salt electroreduction. The apparatus includes a reactor, a conductor, a power source, a gas charging / discharging mechanism, and a sealing mechanism. The reactor is a barrel-shaped structure with a conductive bottom plate, insulated peripheral walls, and an open end. The reactor cavity is configured to sequentially lay the reactant and molten salt from bottom to top. The conductor is used to insert the molten salt. The reactor and conductor are located inside the sealing mechanism, while the power source is located outside the sealing mechanism. The positive terminal of the power source is electrically connected to the conductor, and the negative terminal is electrically connected to the bottom plate. The gas charging / discharging mechanism is configured to continuously charge the reactor with protective gas while simultaneously discharging waste gas.

[0023] The apparatus for preparing metal by molten salt electroreduction provided in this invention comprises a reactor and a conductor located inside a closed mechanism, with a power source located outside the closed mechanism. The reactant and molten salt are sequentially laid from bottom to top inside the reactor chamber. A gas filling and venting mechanism and a sealing mechanism are installed. The positive terminal of the power source is electrically connected to the conductor, and the negative terminal is electrically connected to the bottom plate of the reactor. The reactor is heated until the molten salt melts, and then the conductor is inserted into the molten salt. Protective gas is continuously introduced into the reactor through the gas filling and venting mechanism, while waste gas is simultaneously vented. The power source is turned on to perform the molten salt electroreduction. When the reaction in the reactor chamber is complete, the power source is turned off, the molten salt in the upper part of the chamber is poured out, and the remaining material in the lower part is removed. Finally, the metal is obtained from the remaining material. The apparatus for preparing metals by molten salt electroreduction provided in this invention has a conductive bottom plate and insulated peripheral walls. The cathode of the molten salt electroreduction reaction is the conductive bottom plate of the reactor. The reactant and molten salt are sequentially laid from bottom to top within the reactor cavity. The reactant only contacts the conductive bottom plate, allowing electrons to move upwards during molten salt electroreduction and directing current transmission. The molten salt electroreduction process proceeds gradually from bottom to top, forming a "resistive" reaction structure, which improves current utilization efficiency. The apparatus for preparing metals by molten salt electroreduction provided in this application has a simple process flow, does not require large amounts of coke as a reducing agent or raw material, does not consume large amounts of non-renewable coal resources, and does not generate large amounts of CO2, toxic gases, or slag, resulting in less environmental pollution. It achieves high efficiency and low cost, and can perform molten salt electroreduction at lower operating temperatures, efficiently preparing metals without relying on coke. The lower operating temperature of the apparatus allows for the molten salt electroreduction process of the reactant within a lower temperature range, which helps reduce energy consumption during the heating process. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of an apparatus for preparing metals by molten salt electroreduction, provided in an embodiment of this application.

[0026] Figure 2 A schematic diagram of another apparatus for preparing metals by molten salt electroreduction provided in an embodiment of this application;

[0027] Figure 3 A photograph of the iron powder obtained after washing the residue prepared in Example 1 of this application;

[0028] Figure 4 A photograph of an iron block obtained by induction melting heating of the residue prepared in Example 1 of this application;

[0029] Figure 5 The XRD pattern of the metal after molten salt electroreduction in Example 1 of this application;

[0030] Figure 6 This is a photograph of the metal obtained after the electroreduction of TiO2 molten salt in Example 2 of this application;

[0031] Figure 7 The image shows the XRD pattern of the metal obtained by molten salt electroreduction in Example 2 of this application.

[0032] Icons: 1-Reactor; 11-Conductive base plate; 12-First insulating cylinder; 13-Conductive barrel; 14-Second insulating cylinder; 2-Conductive body; 3-Power supply; 4-Gas charging and discharging mechanism; 41-Gas tank; 42-Inflating pipe; 43-Exhaust pipe; 5-Sealing mechanism; 51-Furnace shell; 52-Insulation layer; 53-Furnace chamber; 54-Furnace cover; 6-Reactant; 61-Metal oxide; 62-Conductive agent; 7-Molten salt; 8-First conductive rod; 9-Second conductive rod. Detailed Implementation

[0033] 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, not all, of the embodiments of the present invention. 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.

[0034] In the description of the embodiments of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of the present invention and for 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 the present invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, the terms "installed," "connected," and "linked" 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 connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0035] Please refer to Figure 1 and Figure 2 As shown, this invention provides an apparatus for preparing metals by molten salt electroreduction, comprising a reactor 1, a conductor 2, a power source 3, a gas charging and discharging mechanism 4, and a sealing mechanism 5. The metal prepared can be a pure metal or an alloy.

[0036] Reactor 1 is a barrel-shaped structure with a conductive bottom plate, insulated peripheral walls, and an open end. The chamber of reactor 1 is configured to sequentially lay the reactant 6 and molten salt 7 from bottom to top. The bottom plate of reactor 1 can be made of metals such as stainless steel, iron, and titanium, or conductive materials such as graphite. The peripheral walls can be made of high-temperature resistant insulating materials such as corundum and magnesium oxide. Molten salt 7 serves as the electrolyte for the electroreduction of the molten salt.

[0037] Conductor 2 is used to insert the molten salt substance 7. Conductor 2 can be made of graphite. The shape of conductor 2 can be columnar, frustum-shaped, etc.; this embodiment uses a graphite rod as an example. The rod shape has a smooth outer wall, does not stick to substances, and is easy to process. Graphite has good electrical conductivity and chemical stability, and is stable to most acids. It has a small coefficient of linear expansion, low sensitivity to temperature changes, and high thermal stability, effectively resisting thermal shock. Graphite has extremely low affinity with most media, and the surface of the graphite rod is not prone to scaling, which does not easily affect conductivity. Graphite has good processing performance; except for rolling and forging, it can be subjected to various mechanical processing methods.

[0038] Reactor 1 and conductor 2 are located inside the enclosed mechanism 5, while power source 3 is located outside the enclosed mechanism 5. Figure 1 and Figure 2As shown, the sealing mechanism 5 can be a heating furnace or other enclosed body. When the sealing mechanism 5 is a heating furnace, the heating furnace includes a furnace shell 51, an insulation layer 52, a furnace chamber 53, and a furnace cover 54. The reactor 1 and the conductor 2 are disposed inside the furnace chamber 53. When the sealing mechanism 5 is an enclosed body, components such as the reactor 1 and the conductor 2 can be pre-installed, and the entire device can be placed in the application environment when needed.

[0039] The positive terminal of power supply 3 is electrically connected to conductor 2, and the negative terminal of power supply 3 is electrically connected to the base plate. The gas charging and discharging mechanism 4 is configured to continuously charge protective gas into reactor 1 while simultaneously discharging waste gas. Specifically, as follows... Figure 1 and Figure 2 As shown, the gas filling and discharging mechanism 4 includes a gas tank 41, a filling pipe 42, and a discharging pipe 43. One end of the filling pipe 42 is connected to the outlet of the gas tank 41, and the other end extends through the top cover of the sealing mechanism 5 and into the interior of the sealing mechanism 5 to continuously fill the reactor 1 with protective gas. The discharging pipe 43 is inserted into the top cover of the sealing mechanism 5 to discharge waste gas. The gas filling and discharging mechanism 4 fills with protective gas according to actual needs. For example, the protective gas filled in this application is argon, and the gas tank 41 is an argon tank.

[0040] The apparatus for preparing metal by molten salt electroreduction provided in this embodiment of the invention comprises a reactor 1 and a conductor 2 disposed inside a closed mechanism 5, and a power supply 3 disposed outside the closed mechanism 5. The reactant 6 and molten salt 7 are sequentially laid from bottom to top inside the chamber of the reactor 1. A gas filling and exhaust mechanism 4 and a closed mechanism 5 are installed. The positive terminal of the power supply 3 is electrically connected to the conductor 2, and the negative terminal of the power supply 3 is electrically connected to the bottom plate of the reactor 1. The reactor 1 is heated until the molten salt 7 melts, and then the conductor 2 is inserted into the molten salt 7. Protective gas is continuously introduced into the reactor 1 through the gas filling and exhaust mechanism 4, while exhaust gas is simultaneously discharged. The power supply 3 is turned on to perform molten salt electroreduction. When the reaction in the chamber of the reactor 1 is complete, the power supply 3 is turned off, the molten salt 7 in the upper part of the chamber is poured out, and the remaining material in the lower part is removed. Finally, metal is obtained from the remaining material. The apparatus for preparing metals by molten salt electroreduction provided in this embodiment of the invention features a conductive bottom plate and insulated peripheral walls in reactor 1. The cathode of the molten salt electroreduction reaction is the conductive bottom plate of reactor 1. The reactant 6 and molten salt 7 are sequentially laid from bottom to top within the chamber of reactor 1. The reactant 6 only contacts and conducts electricity with the conductive bottom plate of reactor 1. Therefore, during molten salt electroreduction, electrons move upwards from the bottom, and the current is directionally transmitted. The molten salt electroreduction process proceeds gradually from bottom to top, forming a "resistive" reaction structure, which improves the efficiency of current utilization. The apparatus for preparing metals by molten salt electroreduction provided in this embodiment has a simple process flow, does not require the consumption of large amounts of coke as a reducing agent and raw material, does not require the consumption of large amounts of non-renewable coal resources, and does not produce large amounts of CO2, toxic gases, or slag, resulting in less environmental pollution. It achieves high efficiency and low cost, and can perform molten salt electroreduction at relatively low operating temperatures, efficiently preparing metals without relying on coke. The device operates at a low temperature, enabling the molten salt electroreduction process of the reactant 6 to be reacted within a lower temperature range, which helps to reduce the energy consumption of the heating process.

[0041] like Figure 1 As shown, reactor 1 includes a conductive bottom plate 11 and a first insulating cylinder 12. The first insulating cylinder 12 is disposed on the conductive bottom plate 11, thereby making the bottom plate of reactor 1 conductive and the peripheral walls insulating. The reactor 1 of this embodiment has a simple structure, is easy to implement, and has a low cost.

[0042] Furthermore, the outer diameter of the conductive base plate 11 is equal to or greater than the outer diameter of the first insulating cylinder 12, thereby ensuring that the bottom of the reactor 1 chamber is completely conductive, resulting in better performance during molten salt electroreduction. Additionally, it facilitates the electrical connection of the conductive base plate 11 to the power supply 3.

[0043] Optional, such as Figure 1As shown, when reactor 1 includes a conductive base plate 11 and a first insulating cylinder 12, the gas filling pipe 42 of the gas filling and discharging mechanism 4 extends into the upper part of the cylinder cavity of reactor 1. When the protective gas being filled is a gas heavier than the waste gas, such as argon, the protective gas flows downward continuously, which can more fully and quickly expel the waste gas from the cylinder cavity. By extending the gas filling pipe 42 of the gas filling and discharging mechanism 4 into the upper part of the cylinder cavity of reactor 1, the protective gas can fill the cylinder cavity of reactor 1 more quickly.

[0044] Optional, such as Figure 2 As shown, reactor 1 includes a conductive barrel 13 and a second insulating cylinder 14. The second insulating cylinder 14 is inserted into the conductive barrel 13, with its bottom surface abutting against the inner bottom surface of the conductive barrel 13. In this case, the bottom surface of the conductive barrel 13 serves as the bottom plate of reactor 1 for conduction, and the second insulating cylinder 14 serves as the peripheral wall insulation of reactor 1. The reactor 1 provided in this embodiment has a simple structure and is easy to implement. It can utilize an existing graphite crucible as the conductive barrel 13, thus saving costs. The inclusion of the conductive barrel 13 in reactor 1 facilitates the electrical connection of the negative terminal of power supply 3 to the bottom plate of reactor 1. Since the conductive barrel 13 itself is conductive, and the second insulating cylinder 14 is inserted into the conductive barrel 13, any electrical connection between the negative terminal of power supply 3 and any position of the conductive barrel 13 can achieve electrical connection between the negative terminal of power supply 3 and the bottom plate of reactor 1 without affecting the insulation of the second insulating cylinder 14.

[0045] Furthermore, when reactor 1 includes a conductive barrel 13 and a second insulating cylinder 14, after the second insulating cylinder 14 is inserted into the conductive barrel 13, the height of the outer wall of the conductive barrel 13 is lower than the height of the second insulating cylinder 14, thereby preventing the formation of an electrical isolation layer at the opening of reactor 1, which would affect the effect of molten salt electroreduction.

[0046] like Figure 2 As shown, when the reactor 1 includes a conductive barrel 13 and a second insulating cylinder 14, due to the setting of the conductive barrel 13, the gas filling pipe 42 of the gas filling and discharging mechanism 4 extends into the gap between the inner cavity of the sealing mechanism 5 and the conductive barrel 13, which facilitates the installation of the conductive barrel 13 and the second insulating cylinder 14 and their placement within the sealing mechanism 5.

[0047] like Figure 1 and Figure 2As shown, the apparatus for preparing metal by electroreduction of molten salt also includes a first conductive rod 8. One end of the first conductive rod 8 is electrically connected to the conductor 2, and the other end extends through the enclosed mechanism 5 and is electrically connected to the positive terminal of the power supply 3. The first conductive rod 8 can be a steel rod, which is readily available and inexpensive. Since the conductor 2 is used to insert the molten salt substance 7, connecting one end of the first conductive rod 8 to the conductor 2 and the other end through the enclosed mechanism 5 to the positive terminal of the power supply 3, i.e., the first conductive rod 8 is inserted into the top cover of the enclosed mechanism 5, makes it easy to fix the conductor 2 so that it does not fall off, and also makes it easy to determine the relative position of the conductor 2 and the molten salt substance 7, without affecting the electrical connection between the conductor 2 and the power supply 3. Of course, the conductor 2 can also be directly electrically connected to the power supply 3 through a wire.

[0048] Furthermore, the apparatus for preparing metal by molten salt electroreduction also includes a second conductive rod 9. The second conductive rod 9 can be a steel rod. One end of the second conductive rod 9 is electrically connected to the bottom plate of the reactor 1, and the other end passes through the enclosed mechanism 5 and is electrically connected to the negative terminal of the power supply 3. The second conductive rod 9 facilitates the electrical connection between the negative terminal of the power supply 3 and the bottom plate, and its fixed rod shape makes it easier to set up and install. When the reactor 1 includes a conductive bottom plate 11 and a first insulating cylinder 12, the outer diameter of the conductive bottom plate 11 is equal to or greater than the outer diameter of the first insulating cylinder 12, which facilitates the electrical connection between the second conductive rod 9 and the conductive bottom plate 11. It is only necessary to bring the outer edge of the conductive bottom plate 11 into contact with the second conductive rod 9. The second insulating cylinder 14 ensures that the peripheral wall of the reactor 1 remains insulated after the second conductive rod 9 is installed. Of course, the conductor 2 can also be electrically connected to the power supply 3 via a wire. In addition, since the apparatus needs to be heated during molten salt electroreduction, the first conductive rod 8 and the second conductive rod 9 must be heat-resistant.

[0049] Another embodiment of the present invention provides a method for preparing metals by molten salt electroreduction, using the above-described apparatus for preparing metals by molten salt electroreduction, including steps 301-305:

[0050] Step 301: The reactant 6 and molten salt 7 are laid in the chamber of reactor 1 from bottom to top.

[0051] The molten salt substance 7 is one or more of chlorides or fluorides. Preferably, the molten salt substance 7 is multiple of chlorides or fluorides, thus making the electrolyte a molten salt mixture. This lowers the eutectic temperature of the molten salt substance 7, reduces the temperature required to heat the molten salt substance 7 during the electroreduction process, and enables the electroreduction of the molten salt substance 7 within a temperature range of 600℃-1200℃. For example, the molten salt substance 7 can be composed of one or more of NaCl, KCl, CaCl2, NaF, KF, CaF2, etc.

[0052] The reactant 6 includes a metal oxide 61 and a conductive agent 62. The conductive agent 62 is part of the metal to be prepared, so when the reactant 6 has reacted completely, there is no need to remove the conductive agent 62, and the conductive agent 62 also becomes part of the prepared metal.

[0053] Conductive agent 62 acts as both a conductive medium and an induction medium for metal oxide 61 during the molten salt electroreduction process. As a conductive medium, conductive agent 62 is doped between the metal oxide 61 powder particles, ensuring uniform distribution of conductive agent 62 among them. This increases the conductivity of the reactant 6, enhances current conduction and electrochemical reaction kinetics, and improves the reaction efficiency of molten salt electroreduction. Compared to existing technologies, it eliminates the need for coke, significantly reducing energy consumption and environmental pollution. As an induction medium, conductive agent 62 can provide auxiliary internal heating during induction heating of the device. The metal oxide 61 in the reactant 6 can be in powder form for molten salt electroreduction without sample pressing, shortening the metal preparation time. Furthermore, the metal oxide 61 has a large specific oxygen surface area, resulting in a fast reaction rate. For example, conductive agent 62 can be various biomass carbon powders or metal powders such as Al, Fe, and Ti. Specifically, a mixture of metal oxide 61 and conductive agent 62 is laid and compacted at the bottom of reactor 1, and then molten salt 7 is spread evenly on top, forming the structural feature of a lower reactant 6 and an upper molten salt 7.

[0054] Step 302: After heating reactor 1 until the molten salt 7 melts, insert conductor 2 into the molten salt 7. For example, this heating process can be induction heating, resistance wire heating, or fuel combustion heating.

[0055] Step 303: Continuously inject protective gas into reactor 1 through gas filling and exhaust mechanism 4, while simultaneously venting waste gas. Turn on power supply 3 to perform molten salt electroreduction. For example, argon gas from the argon tank is continuously injected into reactor 1 through filling pipe 42, while air and other waste gases are vented through exhaust pipe 43. The waste gas overflows from the molten salt substance 7 under buoyancy. Connect the positive terminal of power supply 3 to conductor 2 and the negative terminal of power supply 3 to the bottom plate of reactor 1, using a constant current or constant voltage for electroreduction.

[0056] Step 304: The reaction in the barrel cavity is over. Disconnect the power supply 3, pour out the molten salt substance 7 from the upper part of the barrel cavity, and remove the remaining substance from the lower part.

[0057] Step 305: Obtain the metal from the retained material.

[0058] Further, step 305: obtaining the metal from the residue, including:

[0059] The residue was repeatedly immersed in ultrapure water to obtain powdered metal. Specifically, after the lower solid residue was cooled, the residue obtained after molten salt electroreduction was immersed in ultrapure water to remove residual molten salt material 7. This process was repeated 3-4 times, followed by rinsing with anhydrous alcohol and drying to obtain powdered metal.

[0060] Optionally, step 305: Obtaining the metal from the residue, including:

[0061] The residue is heated to the metal's melting point to obtain liquid or bulk metal. For example, the residue is subjected to induction melting heating, causing the residual molten salt 7 in the residue to volatilize and be recovered, and liquid or bulk metal can be obtained after reaching the metal's melting point.

[0062] Repeat steps 301-305 above to continuously reduce the metal oxide 61 to metal. Meanwhile, the poured-out molten salt material 7 can be reused repeatedly, which can avoid the defects of traditional processes such as ironmaking that produce a large amount of slag.

[0063] The method for preparing metals by molten salt electroreduction provided in this application has fewer process steps and can reduce the cost of metal preparation.

[0064] The specific embodiments of the apparatus and method for preparing metals by molten salt electroreduction provided in this application are as follows.

[0065] Example 1: Preparation of metallic iron by molten salt electroreduction

[0066] A corundum tube was inserted into a conductive crucible to obtain reactor 1. A mixture of 20 g Fe3O4 and 0.8 g carbon powder, as the reactant 6, was laid at the bottom of reactor 1 and compacted. Then, 160 g of a molten salt mixture of NaCl and NaF with a molar ratio of 1:1 was laid on top. Reactor 1 was placed in a heating furnace and heated. After the temperature reached 800 °C, the molten salt electroreduction process began. Argon gas was continuously introduced into the heating furnace through the gas filling and exhaust mechanism 4 for protection, preventing the metal from oxidizing at high temperatures.

[0067] Connect the power supply 3 (Goowell PSM-3004) to the cathode (bottom of reactor 1) and anode (graphite rod) of the device, respectively. Perform a molten salt electroreduction process at a current of 2.0 A for 7.0 h to completely reduce Fe3O4 to iron metal.

[0068] After the reaction in the chamber of reactor 1 is completed, power supply 3 is disconnected, the crucible is removed, and the molten salt material 7 is poured out and stored for recycling. Two methods can be used to separate the remaining molten salt material 7 from the metallic iron. (1) Water washing method: After the crucible cools, the residue in the crucible is soaked and washed in ultrapure water 5-6 times to remove the remaining molten salt material 7. Then it is rinsed 2-3 times with anhydrous ethanol, dried, and powdered pure metal is obtained, such as... Figure 3 As shown. (2) Heating method: The residue after electroreduction is heated in an induction furnace at a temperature range of 1000℃-1200℃ to volatilize and recover the molten salt substance 7, and obtain blocky metallic iron, such as Figure 4 As shown. The metal after molten salt electroreduction was subjected to XRD analysis, and the results are as follows. Figure 5 As shown. The substances obtained after molten salt electroreduction are all pure iron metals, except for small amounts of Fe and C compounds.

[0069] Example 2: Preparation of Titanium-Aluminum Alloy by Molten Salt Electroreduction

[0070] Reactor 1 was obtained by inserting an insulating sleeve into a graphite crucible, and the gap between the graphite crucible opening and the insulating sleeve was sealed with high-temperature AB glue. A hole with a diameter of 1.5 mm and a depth of 0.5 mm was drilled at the top of the graphite crucible, and a polished wire with a length of 1.5 m was inserted into the hole. The hole opening was then sealed with high-temperature AB glue. The crucible was left to stand at room temperature for 12 hours, and then transferred to a tube furnace. After being held at 100 °C and 150 °C for two hours respectively, the crucible was cooled to room temperature with the furnace and removed.

[0071] 20g of TiO2 was laid and compacted at the bottom of reactor 1. A 29.3g Al ingot was polished smooth and placed on top of the TiO2 sample inside reactor 1. Then, the dried Na3AlF6 molten salt material 7 was laid on top of the Al ingot. Reactor 1 was placed in a heating furnace and heated to 1150℃. Argon gas was continuously introduced into the furnace to protect the metal from oxidation at high temperatures. The power supply 3 (Goowell PSM-3004) was connected to the cathode (bottom of the graphite crucible) and anode (graphite rod) of the device.

[0072] An electroreduction process was performed at 3.0 V for 60 min to completely reduce TiO2 to Al3Ti. After the molten salt electroreduction was completed, power supply 3 was disconnected, the graphite crucible was removed, and the molten salt material 7 was poured out and stored for recycling. After the crucible cooled, the remaining material in the crucible was soaked and washed 5-6 times with ultrapure water to remove residual molten salt material 7. Then, the product was placed in 0.1 mol / L dilute hydrochloric acid for further impurity removal, and finally rinsed 2-3 times with anhydrous ethanol, dried, and sealed for storage. The metal after molten salt electroreduction is as follows: Figure 6 The metal shown is gray, and after polishing, it has a metallic luster. The XRD test results of this metal are as follows: Figure 7It contains only the Al3Ti phase and no other impurities, and its diffraction peaks do not shift compared to the standard card.

[0073] Example 3: Cost Analysis of Molten Salt Electroreduction for the Preparation of Metallic Iron

[0074] 1. Main Costs

[0075] (1) Raw material cost: The raw materials are iron ore powder and biochar. The main component of the iron ore powder used in the laboratory stage is Fe3O4, and the added carbon source is biochar. In the industry, semi-coke, which is cheaper than metallurgical coke, can be used as a substitute. According to data from Steel Union, the market prices of iron ore powder and semi-coke are about RMB769 / ton and RMB1616.67 / ton, respectively.

[0076] (2) Electricity consumption cost of molten salt electrolytic reduction process

[0077] Taking constant current electrolysis of 2.0 A for 7 hours as an example, the power consumption can be calculated to be approximately 28.1 W·h, or 0.0281 kWh, from the voltage curve of the molten salt electroreduction process. Based on an industrial electricity price of 0.5 yuan / kWh, the power consumption for this process is 0.01405 yuan.

[0078] 2. Raw material and electricity consumption when producing 1 ton of reduced iron powder

[0079] In the experiment, 20g of Fe3O4 (iron ore powder) and 0.8g of biochar (semi-coke) were electrolyzed at a constant current of 2.0 A for 7 hours, recovering 10.04g of iron. The calculated electricity consumption for this process was 0.0281 kWh (equivalent to 0.01405 yuan at a price of 0.5 yuan / kWh). Scaled up proportionally, it can be calculated that producing 1 ton of iron requires 2800 kWh of electricity. Based on an industrial electricity price of 0.5 yuan / kWh, the electricity cost for producing 1 ton of iron is approximately 1400 yuan.

[0080] 3. Main costs of producing 1 ton of reduced iron powder

[0081] Producing 1 ton of iron requires 1.992 tons of iron ore powder, 0.07968 tons of semi-coke, and 2800 kWh of electricity. Therefore, the cost of producing 1 ton of iron using this process can be calculated to be approximately 3060.65 yuan. This is significantly lower than the cost of producing 1 ton of iron using existing technologies.

[0082] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0083] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. An apparatus for preparing metals by molten salt electroreduction, characterized in that, Includes reactor, conductor, power source, gas filling and discharging mechanism, and sealing mechanism; The reactor is a barrel with a conductive bottom plate, insulated peripheral walls, and an open end. The barrel cavity of the reactor is configured to be lined with the reactant and molten salt from bottom to top. The reactant includes metal oxides and conductive agents, and the conductive agent is part of the composition of the metal being prepared. The molten salt is a variety of fluorides. The reactor includes a conductive barrel and a second insulating cylinder; The second insulating cylinder is inserted into the conductive barrel, with its bottom surface abutting against the inner bottom surface of the conductive barrel, and the outer wall of the conductive barrel is higher than the height of the second insulating cylinder; The conductor is used to insert the molten salt material after it has been melted; The reactor and the conductor are disposed inside the enclosed mechanism, and the power source is disposed outside the enclosed mechanism; The enclosed mechanism is a heating furnace, which includes a furnace shell, an insulation layer, a furnace chamber, and a furnace cover. The reactor and the conductor are disposed inside the furnace chamber. The positive terminal of the power supply is electrically connected to the conductor, and the negative terminal of the power supply is electrically connected to the base plate. The gas filling and discharging mechanism is configured to continuously fill the reactor with protective gas while simultaneously discharging waste gas.

2. The apparatus for preparing metals by molten salt electroreduction according to claim 1, characterized in that, The reactor includes a conductive base plate and a first insulating cylinder, the first insulating cylinder being disposed on the conductive base plate.

3. The apparatus for preparing metals by molten salt electroreduction according to claim 2, characterized in that, The outer diameter of the conductive base plate is equal to or greater than the outer diameter of the first insulating cylinder.

4. The apparatus for preparing metals by molten salt electroreduction according to claim 1, characterized in that, It also includes a first conductive rod; One end of the first conductive rod is electrically connected to the conductor, and the other end extends out of the enclosed mechanism and is electrically connected to the positive terminal of the power supply.

5. A method for preparing metals by molten salt electroreduction, characterized in that, The apparatus for preparing metals using molten salt electroreduction according to any one of claims 1 to 4 comprises: The reactor chamber is lined with the reactant and the molten salt from bottom to top. After heating the reactor until the molten salt melts, the conductor is inserted into the molten salt. Protective gas is continuously introduced into the reactor through the gas filling and discharging mechanism, while exhaust gas is discharged, and the power supply is turned on to perform molten salt electroreduction. Once the reaction in the barrel cavity is complete, disconnect the power supply, pour out the molten salt material from the upper part of the barrel cavity, and remove the residue from the lower part. Metal is obtained from the retained material.

6. The method for preparing metals by molten salt electroreduction according to claim 5, characterized in that, Obtaining metal through the retained material includes: The residue was soaked in ultrapure water multiple times to obtain powdered metal.

7. The method for preparing metals by molten salt electroreduction according to claim 5, characterized in that, Obtaining metal through the retained material includes: The residue is heated to the metal melting point to obtain liquid or bulk metal.

8. The method for preparing metals by molten salt electroreduction according to claim 5, characterized in that, The molten salt substance is one or more of chlorides or fluorides.

9. The method for preparing metals by molten salt electroreduction according to claim 5, characterized in that, The reactants include metal oxides and conductive agents.

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