Metal-inorganic salt composite reducing agent, preparation method and device and micro-nano material

Abstract

The application discloses a metal-inorganic salt composite reducing agent and a preparation method and equipment thereof and micro-nano material, and belongs to the technical field of metal reducing agents. The preparation comprises the following steps: mixing liquid metal elements with metal inorganic salts, cooling and solidifying, and then performing particle size grading to obtain a metal-inorganic salt composite reducing agent with a preset particle size. The obtained composite reducing agent maintains the reaction activity of micro-nano metal particles formed by liquid metal, and due to the presence of the metal inorganic salt, the composite reducing agent has good stability and can effectively avoid potential safety hazards of micro-nano metal powder in the production, transportation and use processes. The composite reducing agent can be used for the preparation of various micro-nano materials based on metal thermal reduction reaction. Since the metal inorganic salt has the functions of heat absorption and isolation, the metal inorganic salt can absorb excessive heat generated in the metal thermal reduction reaction process, stabilize the reaction system temperature, and greatly improve the uniformity of the micro-nano material.

Description

Technical Field

[0001] This invention relates to the field of metal reducing agent technology, and more specifically, to a metal-inorganic salt composite reducing agent, its preparation method and equipment, and micro / nano materials. Background Technology

[0002] Reactive metals (such as magnesium and aluminum) are widely used as reducing agents in chemical reactions, such as reducing silicon dioxide to prepare elemental silicon and silicon carbide. To make the reaction process more uniform and efficient, metal reducing agents are generally processed into powder, then mixed with other reactants, and heated to prepare the target product. However, metal powders react violently with oxygen, releasing a large amount of heat, which can easily lead to fires or even explosions. Therefore, ensuring the safe production and utilization of metal powders is a significant challenge that urgently needs to be addressed. Furthermore, since the reaction between metal powders and other materials often involves a large amount of exothermic reaction, this can potentially lead to excessively high reaction temperatures, affecting the performance of the target product.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] One of the objectives of this invention is to provide a method for preparing a metal-inorganic salt composite reducing agent, so as to solve at least one of the above-mentioned technical problems.

[0005] The second objective of this invention is to provide a metal-inorganic salt composite reducing agent prepared by the above-described preparation method.

[0006] The third objective of this invention is to provide a micro / nano material prepared using the aforementioned metal-inorganic salt composite reducing agent.

[0007] The fourth objective of this invention is to provide a preparation apparatus used in the preparation process of the above-mentioned metal-inorganic salt composite reducing agent.

[0008] This application can be implemented as follows:

[0009] In a first aspect, this application provides a method for preparing a metal-inorganic salt composite reducing agent, which includes the following steps:

[0010] Liquid elemental metal is mixed with inorganic metal salt to obtain a composite product with liquid elemental metal introduced on the surface of inorganic metal salt as a template; the composite product is cooled and solidified to obtain a primary product of metal-inorganic salt composite reducing agent; the primary product of metal-inorganic salt composite reducing agent is subjected to particle size classification to obtain a metal-inorganic salt composite reducing agent with a preset particle size.

[0011] In an optional embodiment, the liquid metal element is obtained by electrolysis of a metal chloride or high-temperature melting of a solid metal element, wherein the metal in the metal chloride or solid metal element includes at least one of magnesium and aluminum.

[0012] In an optional embodiment, the particle size of the metal chloride is 20 to 200 mesh.

[0013] In an optional implementation, the process conditions for electrolysis include: a temperature of 600–900°C, a cell voltage of 2.0–5.0V, and an electrolysis time of 1–12h.

[0014] In an optional implementation, the electrolysis process is carried out under a protective atmosphere.

[0015] In an optional implementation, the protective atmosphere is an inert atmosphere.

[0016] In an optional implementation, the inert atmosphere includes an argon atmosphere or a helium atmosphere.

[0017] In an optional embodiment, when obtaining liquid metal by high-temperature melting of solid metal elements, an inorganic metal salt is added and mixed with the solid metal element before high-temperature melting.

[0018] In an optional embodiment, the metal inorganic salt includes at least one of lithium chloride, potassium chloride, calcium chloride, sodium chloride, and magnesium chloride.

[0019] In an optional embodiment, the particle size of the metal inorganic salt is 20 to 100 mesh.

[0020] In an optional embodiment, the mass ratio of the metal inorganic salt to the metal chloride or solid metal element is 1:1 to 10:1.

[0021] In an optional implementation, the heating process involves continuous stirring of the mixture using a stirring rod.

[0022] In an optional embodiment, the particle size of the solid metal element is 5 to 100 mesh.

[0023] In an optional embodiment, the high-temperature melting temperature is 650–1000°C, and the melting time is 1–5 hours.

[0024] In an optional implementation, the high-temperature melting process is carried out under a protective atmosphere.

[0025] In an optional implementation, the protective atmosphere is an inert atmosphere.

[0026] In an optional implementation, the inert atmosphere includes an argon atmosphere or a helium atmosphere.

[0027] In an optional embodiment, mixing is carried out at 600–800°C.

[0028] In an optional embodiment, mixing is carried out at 650–700°C.

[0029] In an optional implementation, mechanical stirring or high-pressure airflow is used as an aid during the mixing process.

[0030] In an optional implementation, cooling and curing are carried out using either air cooling or water cooling.

[0031] In an optional embodiment, the temperature of the initial product of the metal-inorganic salt composite reducing agent obtained after cooling and curing is 20–80°C.

[0032] In an optional embodiment, particle size classification involves separating the initial product of the metal-inorganic salt composite reducing agent into large particles with a diameter greater than 1 mm and small particles with a diameter less than 1 mm; wherein, the small particles with a diameter less than 1 mm are metal-inorganic salt composite reducing agents with a preset particle size.

[0033] In an optional implementation, large-particle primary products are recycled for use in the mixing process.

[0034] In an optional embodiment, the entire preparation process of the metal-inorganic salt composite reducing agent is carried out under a protective atmosphere.

[0035] In an optional implementation, the protective atmosphere is an inert atmosphere.

[0036] In an optional implementation, the inert atmosphere includes an argon atmosphere or a helium atmosphere.

[0037] Secondly, this application provides a metal-inorganic salt composite reducing agent, which is prepared by any of the preparation methods described in the foregoing embodiments.

[0038] Thirdly, this application provides a micro / nano material obtained by performing a metal thermal reduction reaction using the metal-inorganic salt composite reducing agent of the aforementioned embodiments as a reducing agent.

[0039] Fourthly, this application provides a preparation apparatus for the preparation method of the metal-inorganic salt composite reducing agent as described in any of the foregoing embodiments, including a high-temperature mixing chamber, a cooling chamber, a grading device, and a grading chamber.

[0040] The high-temperature mixing chamber is equipped with a first inlet for introducing liquid metal elements, a second inlet for introducing metal inorganic salts, and a mixing chamber outlet for discharging composite products.

[0041] The cooling chamber is equipped with a composite product inlet and a composite product outlet, with the composite product inlet connected to the mixing chamber outlet;

[0042] The classification device includes a metal-inorganic salt composite reducing agent primary product inlet, a large particle outlet, and a small particle outlet. The composite product outlet is connected to the metal-inorganic salt composite reducing agent primary product inlet.

[0043] The grading silo includes a large particle silo and a small particle silo. The large particle outlet is connected to the large particle silo, and the small particle outlet is connected to the small particle silo.

[0044] In an optional implementation, the high-temperature mixing silo is further provided with a large particle recycling inlet, and the large particle silo is further provided with a large particle recycling outlet, which is connected to the large particle recycling inlet.

[0045] In an optional embodiment, when the liquid metal element is obtained by electrolysis of a metal chloride, the preparation equipment further includes an electrolysis device; the electrolysis device includes an electrolytic cell for electrolyzing the metal chloride and a liquid metal element collection chamber for collecting the liquid metal element obtained by electrolysis; the electrolytic cell includes a cathode chamber, an anode chamber, and a first partition for separating the cathode chamber and the anode chamber; an anode is provided in the anode chamber, and a cathode is provided in the cathode chamber; a second partition is provided between the cathode chamber and the liquid metal element collection chamber, and the second partition has a channel to allow the liquid metal element in the cathode chamber to flow into the liquid metal element collection chamber.

[0046] In an alternative embodiment, the anode is a graphite anode, or the cathode is a stainless steel rod.

[0047] In an optional embodiment, the electrolytic cell is provided with a first feed port for introducing metal chloride into the anode chamber, a second feed port for introducing metal chloride into the cathode chamber, and a gas inlet for introducing protective gas, wherein the metal chloride introduced into the first feed port and the second feed port independently includes at least one of lithium chloride, potassium chloride, calcium chloride, sodium chloride, magnesium chloride, and barium chloride.

[0048] In an optional embodiment, the preparation equipment further includes a gas recovery system, which includes a gas collection hood and a gas pipeline, with both ends of the gas pipeline connected to the electrolytic cell and the gas collection hood, respectively.

[0049] In an optional embodiment, when the liquid metal element is obtained by melting the solid metal element at high temperature, the preparation equipment further includes a metal melting container (such as a metal melting chamber); the metal melting container has a heating device inside, and the metal melting container is provided with a feed port for introducing the solid metal element, a gas inlet for introducing protective gas, and a discharge port for discharging the liquid metal element.

[0050] The beneficial effects of this application include:

[0051] This application introduces inorganic metal salts during the preparation of metal powder reducing agents. When the inorganic metal salts are mixed with liquid metal elements, the liquid metal elements are diluted and dispersed. After cooling and solidification, small-diameter reduced metal particles are obtained. Furthermore, the mixed product dilutes the concentration of the metal powder, reducing the heat released in the reaction and also mitigating the hazards in case of accidents through the heat absorption of the metal salts. The resulting metal-inorganic salt composite reducing agent maintains the reactivity of micro / nano metal particles formed from liquid metal, while the presence of the inorganic metal salt provides good stability, effectively avoiding potential safety hazards during the production, transportation, and use of nano / micro metal powders. This composite reducing agent can be used to prepare various micro / nano materials based on metal thermal reduction reactions. Because the inorganic metal salts also have heat absorption and isolation functions, they can absorb excess heat generated during the metal thermal reduction reaction, stabilize the reaction system temperature, and greatly improve the uniformity of the micro / nano materials. Attached Figure Description

[0052] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 A schematic diagram of the structure of the first preparation equipment for the metal-inorganic salt composite reducing agent provided in this application;

[0054] Figure 2 A schematic diagram of the structure of the second preparation device for the metal-inorganic salt composite reducing agent provided in this application;

[0055] Figure 3 A photograph of the original solid metallic element used in the application examples of this application;

[0056] Figure 4 A photograph of the metal-inorganic salt composite reducing agent obtained in the application example of this application;

[0057] Figure 5 The image shows the XRD pattern of silicon-based nano / micromaterials in the application example of this application.

[0058] Icons: 10-High-temperature mixing bin; 11-First feed inlet; 12-Second feed inlet; 13-Mixing bin outlet; 14-Large particle recovery inlet; 15-Vertical stirring rod; 16-Helical stirring blade; 20-Cooling bin; 21-Composite product inlet; 22-Composite product outlet; 30-Classification device; 31-Metal-inorganic salt composite reducing agent primary product inlet; 32-Large particle outlet; 33-Small particle outlet; 40-Classification bin; 41-Large particle bin; 411- 42 - Large particle recovery outlet; 50 - Small particle bin; 51 - Electrolysis unit; 51 - Electrolytic cell; 511 - Cathode chamber; 5111 - Cathode; 512 - Anode chamber; 5121 - Anode; 513 - First partition; 52 - Liquid metal element collection chamber; 53 - Second partition; 531 - Channel; 541 - First feed port; 542 - Second feed port; 543 - Gas inlet; 60 - Metal melting container; 61 - Feed port; 62 - Gas inlet; 63 - Discharge port. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0060] The following provides a detailed description of the metal-inorganic salt composite reducing agent, its preparation method and equipment, and the micro / nano materials provided in this application.

[0061] This application proposes a method for preparing a metal-inorganic salt composite reducing agent, which includes the following steps:

[0062] Liquid elemental metal is mixed with inorganic metal salt to obtain a composite product with liquid elemental metal introduced on the surface of inorganic metal salt as a template; the composite product is cooled and solidified to obtain a primary product of metal-inorganic salt composite reducing agent; the primary product of metal-inorganic salt composite reducing agent is subjected to particle size classification to obtain a metal-inorganic salt composite reducing agent with a preset particle size.

[0063] The above process introduces inorganic metal salts during the preparation of metal powder. When the inorganic metal salts are mixed with the molten metal, they dilute and disperse the molten metal. After cooling and solidification, small-sized reduced metal particles are obtained. Furthermore, the mixed product dilutes the concentration of the metal powder, reducing the heat released by the reaction and also mitigating the hazards in the event of an accident through the heat absorption of the metal salts. Therefore, metal powders with extremely high safety can be prepared.

[0064] In some embodiments, the liquid metal element can be obtained by electrolysis of a metal chloride. In other embodiments, the liquid metal element can be obtained by high-temperature melting of a solid metal element. Exemplarily, the metal in the metal chloride or solid metal element includes at least one reactive metal, such as magnesium and aluminum.

[0065] For reference, the particle size of the metal chlorides used in this application is 20 to 200 mesh.

[0066] When preparing liquid metal elements by electrolysis, the corresponding electrolysis process conditions may include: a temperature of 600–900℃, a cell voltage of 2.0–5.0V, and an electrolysis time of 1–12h.

[0067] The temperature used for electrolysis can be, for example, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃ or 900℃, or any other value in the range of 600 to 900℃.

[0068] The cell voltage used for electrolysis can be, for example, 2V, 2.5V, 3V, 3.5V, 4V, 4.5V or 5V, or any other value in the range of 2.0 to 5.0V.

[0069] The electrolysis time can be 1h, 2h, 4h, 6h, 8h, 10h or 12h, or any other value within the range of 1 to 12h.

[0070] The above electrolysis process is carried out under a protective atmosphere, which is mainly an inert atmosphere, such as an argon atmosphere or a helium atmosphere.

[0071] When preparing liquid metal elements using a high-temperature melting method, any temperature that can melt solid metal elements into liquid metal elements is acceptable.

[0072] For reference, when preparing liquid metal elements by high-temperature melting, an inorganic metal salt is added and mixed with the solid metal element before high-temperature melting.

[0073] In this application, the inorganic metal salt used to prepare the composite reducing agent may, by way of example, include at least one of lithium chloride, potassium chloride, calcium chloride, sodium chloride, and magnesium chloride. The particle size of the inorganic metal salt may also be 20 to 100 mesh. The particle size of the solid metal element may be 5 to 100 mesh, such as 5 mesh, 10 mesh, 20 mesh, 50 mesh, 80 mesh, or 100 mesh.

[0074] The mass ratio of inorganic metal salts to metal chlorides or solid metal elements can be 1:1 to 10:1, such as 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc.

[0075] The mixture is continuously stirred by a stirring rod during the heating process.

[0076] The temperature for the above-mentioned high-temperature melting can be 650 to 1000℃ (such as 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃ or 1000℃, etc.), and the melting time can be 1 to 5h (such as 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, etc.).

[0077] Similarly, the high-temperature melting process is also carried out under a protective atmosphere. The protective atmosphere is an inert atmosphere. Inert atmospheres include argon atmospheres or helium atmospheres.

[0078] For reference, the mixing process of liquid metal element and metal inorganic salt can be carried out at 600-800℃ (such as 600℃, 620℃, 650℃, 680℃, 700℃, 720℃, 750℃, 780℃ or 800℃, etc.), preferably at 650-700℃.

[0079] If the mixing temperature is below 600℃, the elemental metal cannot melt; if the mixing temperature is above 800℃, the vapor pressure of the metal will easily increase, accelerating its evaporation and resulting in the loss of some metal.

[0080] Mechanical stirring or high-pressure airflow can be used to assist in the above mixing process.

[0081] By thoroughly mixing liquid metal elements with inorganic metal salts in situ, a composite product can be obtained, which uses inorganic metal salts as templates and introduces liquid metal elements onto the surface of inorganic metal salts.

[0082] In this application, cooling and curing can be carried out by air cooling or water cooling.

[0083] The initial product of the metal-inorganic salt composite reducing agent obtained after cooling and curing can be at a temperature of 20 to 80°C, such as 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, or 80°C, or any other value within the range of 20 to 80°C.

[0084] For reference, particle size classification can be used to separate the initial product of the metal-inorganic salt composite reducing agent into large particles with a diameter greater than 1 mm and small particles with a diameter less than 1 mm. The small particles with a diameter less than 1 mm are the metal-inorganic salt composite reducing agent of the predetermined particle size, which can be used as a reducing agent in chemical reaction processes. The large particles can be recycled back to the mixing process as needed.

[0085] It should be noted that particle size can also be classified according to different diameters as needed, without further restrictions here.

[0086] In this application, the entire preparation process of the metal-inorganic salt composite reducing agent is carried out under a protective atmosphere. Similarly, the protective atmosphere can be an inert atmosphere, such as an argon atmosphere or a helium atmosphere.

[0087] Accordingly, this application provides a metal-inorganic salt composite reducing agent, which is prepared by the above-described preparation method.

[0088] This composite reducing agent maintains the reactivity of micro- and nano-sized metal particles formed from liquid metal. Due to the presence of inorganic metal salts, it has good stability and can effectively avoid potential safety hazards in the production, transportation, and use of nano- and micro-sized metal powders.

[0089] In addition, this application also provides a micro / nano material, which is obtained by carrying out a metal thermal reduction reaction using the above-mentioned metal-inorganic salt composite reducing agent as a reducing agent.

[0090] By adding inorganic metal salts (such as potassium chloride or sodium chloride), the temperature of the reaction system can be maintained by utilizing the endothermic effect of the inorganic metal salts (absorbing excess heat generated during the metallothermal reduction reaction). Furthermore, inorganic metal salts also provide a degree of physical isolation, reducing the aggregation and growth of reaction products and greatly improving the uniformity of micro / nanomaterials. In addition, the use of the aforementioned metal-inorganic salt composite reducing agent to prepare micro / nanomaterials effectively solves the problem of using flammable and explosive metal powders in existing micro / nanomaterial production processes, enabling low-cost, large-scale, and safe preparation of micro / nanomaterials.

[0091] For reference, the micro-nano materials can be, by way of example, silicon-based micro-nano materials, such as elemental silicon or silicon carbide, which can be prepared by reducing silicon dioxide with the aforementioned metal-inorganic salt composite reducing agent.

[0092] It should be noted that the term "micro-nanomaterials" in this application refers to materials with dimensions at the micrometer or nanometer scale.

[0093] In addition, this application also provides a preparation apparatus used in the preparation method of the metal-inorganic salt composite reducing agent described above. Please refer to [reference needed]. Figure 1 and Figure 2 The preparation equipment includes a high-temperature mixing chamber 10, a cooling chamber 20, a grading device 30, and a grading chamber 40.

[0094] The high-temperature mixing chamber 10 is provided with a first inlet 11 for introducing liquid metal elements, a second inlet 12 for introducing metal inorganic salts, and a mixing chamber outlet 13 for discharging composite products.

[0095] The cooling chamber 20 is provided with a composite product inlet 21 and a composite product outlet 22. The composite product inlet 21 is connected to the mixing chamber outlet 13.

[0096] The grading device 30 includes a metal-inorganic salt composite reducing agent primary product inlet 31, a large particle outlet 32, and a small particle outlet 33. The composite product outlet 22 is connected to the metal-inorganic salt composite reducing agent primary product inlet 31.

[0097] The grading chamber 40 includes a large particle chamber 41 and a small particle chamber 42. The large particle outlet 32 ​​is connected to the large particle chamber 41, and the small particle outlet 33 is connected to the small particle chamber 42.

[0098] The high-temperature mixing chamber 10 is also equipped with a vertical stirring rod 15, which has spiral stirring blades 16.

[0099] Furthermore, the high-temperature mixing bin 10 is also equipped with a large particle recycling inlet 14, and the large particle bin 41 is also equipped with a large particle recycling outlet 411. The large particle recycling outlet 411 is connected to the large particle recycling inlet 14, thereby realizing the recycling and utilization of large particle materials.

[0100] The aforementioned grading device 30 can refer to existing conventional grading instruments, as long as it can achieve particle size classification of the primary product of the metal-inorganic salt composite reducing agent.

[0101] In some embodiments, the liquid metal element is obtained by electrolysis of a metal chloride, and accordingly, the preparation equipment also includes an electrolysis device 50 (e.g., Figure 1 ).

[0102] For reference, the electrolysis apparatus 50 includes an electrolytic cell 51 for electrolyzing metal chlorides and a liquid metal collection chamber 52 for collecting the liquid metal obtained from electrolysis. The electrolytic cell 51 includes a cathode chamber 511, an anode chamber 512, and a first partition 513 for separating the cathode chamber 511 and the anode chamber 512. An anode 5121 is disposed in the anode chamber 512, and a cathode 5111 is disposed in the cathode chamber 511. A second partition 53 is disposed between the cathode chamber 511 and the liquid metal collection chamber 52, and the second partition 53 has a channel 531 to allow the liquid metal in the cathode chamber 511 to flow into the liquid metal collection chamber 52.

[0103] The anode 5121 can be, by example, a graphite anode 5121. The cathode 5111 can be, by example, a stainless steel rod. The inner wall of the electrolytic cell 51 may be provided with a refractory lining.

[0104] The width of the channel 531 provided in the second partition 53 (which can also be understood as the height position of the channel 531 of the second partition 53) is adjustable. Most of the liquid metal obtained after electrolysis floats on the liquid surface. By adjusting the width of the channel 531, the liquid metal can be smoothly introduced into the liquid metal collection chamber 52.

[0105] In addition, the electrolytic cell 51 is provided with a first feed port 541 for introducing metal chloride into the anode chamber 512, a second feed port 542 for introducing metal chloride into the cathode chamber 511, and a gas inlet 543 for introducing protective gas. The metal chloride (such as molten metal salt) introduced into the first feed port 541 and the second feed port 542 independently includes at least one of lithium chloride, potassium chloride, calcium chloride, sodium chloride, magnesium chloride, and barium chloride.

[0106] Furthermore, the preparation equipment also includes a gas recovery system (not shown), which comprises a gas collection hood (not shown) and a gas pipeline (not shown). The two ends of the gas pipeline are connected to the electrolytic cell 51 and the gas collection hood, respectively. For example, when the metal chloride is magnesium chloride, elemental magnesium and chlorine gas can be produced after electrolysis, and the gas recovery system can be used to collect the chlorine gas.

[0107] In other embodiments, the liquid metal element is obtained by high-temperature melting of a solid metal element; correspondingly, the preparation equipment also includes a metal melting container 60 (e.g., Figure 2 The metal melting container 60 has a heating device inside (not shown). The metal melting container 60 is provided with a feed port 61 for introducing solid elemental metal, a gas inlet 62 for introducing protective gas, and a discharge port 63 for discharging liquid elemental metal. In addition, a temperature detection instrument (not shown) may also be installed inside the metal melting container 60.

[0108] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0109] Example 1

[0110] This embodiment provides a metal-inorganic salt composite reducing agent, which is prepared by the following method:

[0111] Please combine Figure 1Anhydrous magnesium chloride (100 mesh particle size) is electrolyzed in electrolytic cell 51. The electrolyte is sodium chloride, potassium chloride, and calcium chloride (the molar fractions of the four metal chlorides are 10%:50%:20%:20% respectively). Argon gas is introduced into the cell as a protective atmosphere. The cell temperature is 720℃, the cell voltage is 4.0V, and the electrolysis time is 6 hours. Magnesium droplets floating on the liquid surface are collected in liquid metal collection chamber 52 on one side of electrolytic cell 51 by a liquid level monitor and control system. Then, the liquid metal is transferred to high-temperature mixing chamber 10. The temperature inside the chamber is 680℃, and the chamber is filled with sodium chloride (50 mesh particle size, the mass ratio of anhydrous magnesium chloride to sodium chloride is 1:8). The magnesium liquid and sodium chloride are evenly dispersed under the action of a spiral stirrer. Then, it is transferred to cooling chamber 20 for further stirring and dispersion. The temperature inside the chamber is 30℃. The material is then classified into large and small particles. The large particles (d>1mm) are re-entered into the high-temperature mixing silo 10 for mixing, while the small particles (d<1mm) are the target metal-inorganic salt composite reducing agent.

[0112] Example 2

[0113] This embodiment provides a metal-inorganic salt composite reducing agent, which is prepared by the following method:

[0114] Please combine Figure 2 Magnesium ingots (595mm long × 140mm wide × 96mm high) were melted at 700℃ in a metal melting chamber, with argon gas introduced as a protective atmosphere. The liquid metal was then transferred to a high-temperature mixing chamber 10 at 660℃, filled with potassium chloride (50-mesh particle size, magnesium ingot to potassium chloride mass ratio 1:2). The magnesium liquid and potassium chloride were uniformly dispersed under the action of a spiral stirrer. The mixture was then transferred to a cooling chamber 20 for further stirring and dispersion at 30℃. The material was then classified into large and small particles. Large particles (d > 1mm) were reintroduced into the high-temperature mixing chamber 10 for mixing, while small particles (d < 1mm) became the target metal-inorganic salt composite reducing agent.

[0115] Example 3

[0116] This embodiment provides a metal-inorganic salt composite reducing agent, which is prepared by the following method:

[0117] Please combine Figure 2Magnesium ingots (595mm long × 140mm wide × 96mm high) were melted at 700℃ in a metal melting chamber, with argon gas introduced as a protective atmosphere. The liquid metal was then transferred to a high-temperature mixing chamber 10 at 670℃, filled with sodium chloride (50-mesh particle size, magnesium ingot to sodium chloride mass ratio 1:3). The magnesium liquid and sodium chloride were uniformly dispersed under the action of a spiral stirrer. The mixture was then transferred to a cooling chamber 20 for further stirring and dispersion at 30℃. The material was then classified into large and small particles. Large particles (d > 1mm) were reintroduced into the high-temperature mixing chamber 10 for mixing, while small particles (d < 1mm) became the target metal-inorganic salt composite reducing agent.

[0118] Application Example 1

[0119] This application example uses Figure 3 The solid metallic element shown is used to prepare a metal-inorganic salt composite reducing agent, and the product obtained is as follows. Figure 4 As shown, a silicon-based nanomaterial was obtained by reducing a silicon-containing precursor with this composite reducing agent, as follows:

[0120] Solid elemental metal (magnesium granules, approximately 5 mesh) and inorganic metal salt (sodium chloride) were mixed uniformly at a mass ratio of 1:3.75 and then placed into a molten metal chamber purged with argon gas. The chamber was heated to 700°C and held at that temperature for 2 hours. The magnesium molten metal and sodium chloride were uniformly dispersed under the action of a spiral stirrer. Subsequently, the mixture was cooled to room temperature and the material was collected. The collected material was classified to obtain the target metal-inorganic salt composite reducing agent.

[0121] The metal-inorganic salt composite reducing agent and the silicon-containing precursor (montmorillonite dried and dehydrated at 600℃) were mixed at a mass ratio of 5:1 and then transferred to a rotary tube furnace under an argon atmosphere. The temperature was raised to 650℃ and held for 5 hours. After cooling to room temperature, samples were taken. The reduction product was acid-washed with 1 mol / L hydrochloric acid for 5 hours with stirring, then soaked in 1% hydrofluoric acid for 5 minutes, followed by washing with water until neutral and vacuum drying. The sample was then collected to obtain the target silicon-based nanomaterials. The XRD pattern of the silicon-based nanomaterials is shown below. Figure 5 As shown.

[0122] In summary, the technical solution provided in this application has at least the following advantages:

[0123] (1) The metal inorganic salts and metal chlorides or solid metal elements used in this application are all green, safe, inexpensive and readily available, and have strong scalability and practicality.

[0124] (2) This application uses a metallic inorganic salt as a template, introducing liquid metal onto its surface. By controlling factors such as the ratio of metallic inorganic salt to liquid metal, the type and particle size of the inorganic salt, temperature, pressure (atmospheric pressure), and mixing conditions, the particle size of the metal powder in the inorganic salt can be regulated. Furthermore, based on the fact that some metallic inorganic salts have a certain degree of solubility for elemental metals, the metal powder can be further refined. In addition, the physical isolation effect of the metallic inorganic salt can effectively prevent the liquid metal from agglomerating and growing. This application enables the low-cost and safe preparation of nano- and micro-sized metal powders.

[0125] (3) This application designs supporting equipment for the production process of metal-inorganic salt composite reducing agents, including an electrolytic cell 51 (or metal melting chamber), a high-temperature mixing chamber 10, a cooling chamber 20, a classification device 30, and a classification chamber 40. In the electrolytic cell 51 (or metal melting chamber), liquid metal can be directly obtained by electrolyzing magnesium chloride or high-temperature molten metal blocks; then, the liquid metal is directly fed into the high-temperature mixing chamber 10 containing metal inorganic salts, and mixed by mechanical stirring and high-pressure airflow; the resulting composite product is further fed into the cooling chamber 20, and after cooling and solidification, the initial product of the metal / inorganic salt composite reducing agent is obtained. After particle size separation in the classification chamber 40, the metal-inorganic salt composite reducing agent is obtained. Among them, the large-particle-size product can be further sent to the high-temperature mixing chamber 10 for use. All the above processes are carried out under inert gas protection. This set of equipment can effectively realize the safe, batch, and continuous preparation of metal-inorganic salt composite reducing agents.

[0126] (4) The metal-inorganic salt composite reducing agent obtained in this application maintains the reactivity of micro / nano metal particles while exhibiting good stability due to the presence of the metal inorganic salt. This composite reducing agent can be used to prepare various micro / nano materials based on metal thermal reduction reactions. Since the metal inorganic salt also has endothermic and isolating functions, it can absorb excess heat generated during the metal thermal reduction reaction, stabilize the reaction system temperature, and greatly improve the uniformity of nano / micro materials. Therefore, the solution in this application can effectively avoid potential safety hazards in the production, transportation, and use of nano / micro metal powders.

[0127] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a metal-inorganic salt composite reducing agent, characterized in that, Includes the following steps: Liquid elemental metal is mixed with inorganic metal salt to obtain a composite product with liquid elemental metal introduced on the surface of inorganic metal salt as a template; the composite product is cooled and solidified to obtain a primary product of metal-inorganic salt composite reducing agent; the primary product of metal-inorganic salt composite reducing agent is subjected to particle size classification to obtain a metal-inorganic salt composite reducing agent with a preset particle size; The liquid metal element is obtained by electrolysis of a metal chloride or high-temperature melting of a solid metal element, wherein the metal in the metal chloride or the solid metal element is magnesium; When metal chloride is electrolyzed to obtain liquid metal element, the particle size of the metal chloride is 20~200 mesh; the process conditions of the electrolysis process include: temperature of 600~900℃, cell voltage of 2.0~5.0V, and electrolysis time of 1~12h; the electrolysis process is carried out under a protective atmosphere. When a liquid metal is obtained by high-temperature melting of a solid metal element, the inorganic metal salt includes at least one of potassium chloride and sodium chloride; the mixture is continuously stirred by a stirring rod during the heating process; the particle size of the solid metal element is 5-100 mesh; the high-temperature melting temperature is 650-1000℃, and the melting time is 1-5 hours; the high-temperature melting process is carried out under a protective atmosphere. The particle size of the inorganic metal salt is 20-100 mesh; the mass ratio of the inorganic metal salt to the metal chloride or the solid metal element is 1:1 to 10:

1.

2. The preparation method according to claim 1, characterized in that... The protective atmosphere is an inert atmosphere.

3. The preparation method according to claim 2, characterized in that... The inert atmosphere includes an argon atmosphere or a helium atmosphere.

4. The preparation method according to claim 1, characterized in that, The mixing is carried out at 600~800℃.

5. The preparation method according to claim 4, characterized in that, The mixing is carried out at 650~700℃.

6. The preparation method according to claim 4, characterized in that, Mechanical stirring or high-pressure airflow is used as an aid during the mixing process.

7. The preparation method according to claim 1, characterized in that, Cooling and curing are carried out using either air cooling or water cooling.

8. The preparation method according to claim 7, characterized in that, The initial product of the metal-inorganic salt composite reducing agent obtained after cooling and solidification has a temperature of 20~80℃.

9. The preparation method according to claim 1, characterized in that, Particle size classification is the process of separating the initial product of the metal-inorganic salt composite reducing agent into large particles with a diameter greater than 1 mm and small particles with a diameter less than 1 mm; wherein, the small particles with a diameter less than 1 mm are metal-inorganic salt composite reducing agents with a preset particle size.

10. The preparation method according to claim 9, characterized in that, The large particle product is recycled for use in the mixing process.

11. The preparation method according to claim 1, characterized in that, The entire preparation process of the metal-inorganic salt composite reducing agent was carried out under a protective atmosphere.

12. A preparation apparatus used in the preparation method of the metal-inorganic salt composite reducing agent as described in any one of claims 1 to 11, characterized in that, Includes a high-temperature mixing silo, a cooling silo, a grading device, and a grading silo; The high-temperature mixing chamber is provided with a first inlet for introducing the liquid metal element, a second inlet for introducing the metal inorganic salt, and a mixing chamber outlet for discharging the composite product. The cooling chamber is provided with a composite product inlet and a composite product outlet, and the composite product inlet is connected to the mixing chamber outlet. The grading device includes a metal-inorganic salt composite reducing agent primary product inlet, a large particle outlet, and a small particle outlet, wherein the composite product outlet is connected to the metal-inorganic salt composite reducing agent primary product inlet. The grading bin includes a large particle bin and a small particle bin, with the large particle outlet connected to the large particle bin and the small particle outlet connected to the small particle bin; When the liquid metal element is obtained by electrolysis of a metal chloride, the preparation equipment further includes an electrolysis device; the electrolysis device includes an electrolytic cell for electrolyzing the metal chloride and a liquid metal element collection chamber for collecting the liquid metal element obtained by electrolysis; the electrolytic cell includes a cathode chamber, an anode chamber, and a first partition for separating the cathode chamber and the anode chamber; an anode is provided in the anode chamber, and a cathode is provided in the cathode chamber; a second partition is provided between the cathode chamber and the liquid metal element collection chamber, and the second partition has a channel to allow the liquid metal element in the cathode chamber to flow into the liquid metal element collection chamber; the liquid metal element in the liquid metal element collection chamber enters the high-temperature mixing chamber through the first feed inlet; Alternatively, when the liquid metal is obtained by melting a solid metal at high temperature, the preparation equipment further includes a metal melting container; the metal melting container has a heating device inside, and the metal melting container is provided with a feed port for introducing the solid metal, a gas inlet for introducing protective gas, and a discharge port for discharging the liquid metal; the discharge port for discharging the liquid metal is connected to the first feed port.

13. The preparation apparatus according to claim 12, characterized in that, The high-temperature mixing silo is also equipped with a large particle recycling inlet, and the large particle silo is also equipped with a large particle recycling outlet, which is connected to the large particle recycling inlet.

14. The preparation apparatus according to claim 12, characterized in that, The anode is a graphite anode, or the cathode is a stainless steel rod.

15. The preparation apparatus according to claim 12, characterized in that, The preparation equipment also includes a gas recovery system, which includes a gas collection hood and a gas pipeline. The two ends of the gas pipeline are respectively connected to the electrolytic cell and the gas collection hood.

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