Composite charge for electric smelting furnaces and its use in the formation and reduction of low-conductivity refractory oxide baths

Abstract

The application provides a composite charge for an electric smelting furnace and application of the composite charge in low-conductivity refractory oxide bath formation and reduction, which is designed based on eutectic principle and phase diagram theory and comprises a refractory oxide base, a fluxing agent and a conductive agent. The fluxing agent significantly reduces the complete melting temperature by weakening the strong lattice bonding and forming a eutectic liquid phase; the conductive agent improves the solid-state conductivity at the initial heating stage to start the Joule heat and enhances the ion migration ability after melting. The two agents cooperate to solve the technical problems of slow melting, high energy consumption and unstable bath formation of the refractory oxide caused by poor conductivity, and realize the low-current and rapid formation of a continuous conductive bath. The application also provides a bath formation and reduction method, and the complete melting temperature is adjustable between 2000-2700 DEG C. The application is suitable for electric arc furnaces, plasma furnaces and other electric smelting furnaces.

Description

Technical Field

[0001] This invention belongs to the field of electrothermal melting technology, specifically relating to a composite charge for electric furnaces and its application in the formation and reduction of low-conductivity refractory oxide molten pools. Background Technology

[0002] Electric melting furnaces (such as electric arc furnaces and transferred plasma furnaces) are widely used in high-temperature material preparation, melting reactions, and electrometallurgical processes, such as the preparation of fused magnesia, calcium carbide, silicon carbide, and elemental silicon. The core principle of these devices is to establish a stable electrical path between the electrodes and the material, converting electrical energy into heat energy to heat, melt, and facilitate subsequent reactions. For refractory metal oxides such as magnesium oxide, calcium oxide, and alumina, the ability to quickly establish a conductive path and form a continuous molten pool during electric heating and melting directly determines the melting rate, thermal efficiency, and subsequent heat and mass transfer effects.

[0003] However, the aforementioned refractory metal oxides generally have high melting points and low electrical conductivity, and possess almost no good electrical conductivity at room temperature or in the unmelted state. Therefore, when starting heating in an electric furnace, it is often difficult to quickly establish a stable current path between the electrode and the material, resulting in the Joule heating effect not being fully utilized, which in turn leads to slow molten pool formation, significant local overheating, and increased unit energy consumption.

[0004] In existing technologies, addressing this bottleneck typically relies on increasing input power, extending heating time, or using external auxiliary heating methods to achieve heating and melting. However, these methods suffer from high energy consumption, slow melting initiation, significant localized overheating, and unstable molten pool formation, which in turn affect the reaction rate and the quality of the final product, failing to fundamentally solve the problem of mismatch between low-conductivity materials and strong electric fields. Therefore, there is an urgent need to propose a method that can reduce the liquidus formation temperature of low-conductivity refractory metal oxides in an electric melting furnace, promote the continuous generation of liquid phase, and rapidly establish a stable conductive path to form a molten pool. Summary of the Invention

[0005] To address the technical problems of poor conductivity of refractory oxides leading to difficulty in establishing an initial current path, slow molten pool formation, and high energy consumption in commonly used technologies, this invention provides a composite charge for forming a low-conductivity refractory oxide molten pool in an electric furnace. The composite charge comprises a refractory oxide base material, a flux, and a conductive agent. The conductive agent accounts for 3-7% of the mass fraction of the composite charge, and the mass ratio of the refractory oxide base material to the flux is 1:0.72-1.56. The refractory oxide base material includes at least one of magnesium oxide, calcium oxide, and aluminum oxide.

[0006] Furthermore, the refractory oxide base material includes magnesium oxide; The flux includes at least one of CaO, SiO2, P2O5, TiO2, Al2O3, and Fe2O3; The conductive agent includes fluorides.

[0007] Furthermore, the refractory oxide base material is magnesium oxide; When the flux in the composite furnace charge is composed of P2O5, SiO2, and CaO, and the mass ratio of MgO, P2O5, SiO2, and CaO is 4.5-6:4:2:1, the complete melting temperature of the composite furnace charge is 2000-2100℃. When the flux of the composite furnace charge is composed of P2O5 and SiO2, and the mass ratio of MgO, P2O5 and SiO2 is 5-7:5:2; or when the flux of the composite furnace charge is composed of SiO2, TiO2 and CaO, and the mass ratio of MgO, SiO2, TiO2 and CaO is 9-11:6:3:1, the complete melting temperature of the composite furnace charge is 2100-2200℃. When the flux of the composite furnace charge is P2O5 and the mass ratio of MgO to P2O5 is 8-10:8; or, the flux of the composite furnace charge is composed of SiO2 and TiO2 and the mass ratio of MgO, SiO2, and TiO2 is 5-7:5:2; or, the flux of the composite furnace charge is composed of Al2O3, SiO2, and CaO and the mass ratio of MgO:Al2O3:SiO2:CaO is 8-10:8:3:1, the complete melting temperature of the composite furnace charge is 2200-2300℃. When the flux of the composite furnace charge is composed of Al2O3 and SiO2, and the mass ratio of MgO, Al2O3 and SiO2 is 2-4:2:1, the complete melting temperature of the composite furnace charge is 2300-2400℃. When the flux of the composite furnace charge is SiO2 and the mass ratio of MgO to SiO2 is 4-5.5:4, the complete melting temperature of the composite furnace charge is 2400-2500℃. When the flux of the composite furnace charge is Al2O3 and the mass ratio of MgO to Al2O3 is 4-5.5:4, the complete melting temperature of the composite furnace charge is 2600-2700℃.

[0008] Furthermore, the refractory oxide base material is magnesium oxide; When the flux in the composite charge is composed of P2O5, SiO2, and CaO, and the mass ratio of MgO, P2O5, SiO2, and CaO is 4.5-5.5:4:2:1, the complete melting temperature of the composite charge is 2050-2070℃. When the flux of the composite furnace charge is composed of P2O5 and SiO2, and the mass ratio of MgO, P2O5 and SiO2 is 5.5-6.5:5:2, the complete melting temperature of the composite furnace charge is 2130-2150℃. When the flux of the composite furnace charge is composed of SiO2, TiO2, and CaO, and the mass ratio of MgO, SiO2, TiO2, and CaO is 9.5-10.5:6:3:1, the complete melting temperature of the composite furnace charge is 2170-2190℃.

[0009] Furthermore, the refractory oxide base material is magnesium oxide; When the flux of the composite furnace charge is P2O5 and the mass ratio of MgO to P2O5 is 8.5-9.5:8, the complete melting temperature of the composite furnace charge is 2200-2220℃. When the flux of the composite furnace charge is composed of SiO2 and TiO2, and the mass ratio of MgO, SiO2 and TiO2 is 5.5-6.5:5:2, the complete melting temperature of the composite furnace charge is 2240-2260℃. When the flux of the composite furnace charge is composed of Al2O3, SiO2, and CaO, and the mass ratio of MgO:Al2O3:SiO2:CaO is 8.5-9.5:8:3:1, the complete melting temperature of the composite furnace charge is 2270-2290℃. When the flux of the composite furnace charge is composed of Al2O3 and SiO2, and the mass ratio of MgO, Al2O3 and SiO2 is 2.5-3.5:2:1, the complete melting temperature of the composite furnace charge is 2300-2320℃. When the flux of the composite furnace charge is SiO2 and the mass ratio of MgO to SiO2 is 4.5-5.5:4, the complete melting temperature of the composite furnace charge is 2410-2430℃. When the flux of the composite furnace charge is Al2O3 and the mass ratio of MgO to Al2O3 is 4.5-5.5:4, the complete melting temperature of the composite furnace charge is 2660-2680℃.

[0010] Furthermore, the preparation of the composite furnace charge includes the following steps: The refractory oxide base material, flux, and conductive agent are sequentially mixed and molded to obtain the composite furnace charge; The mixing process includes ball milling; The molding process includes tableting.

[0011] Compared with the prior art, the present invention has at least the following advantages: This invention involves adding a specific proportion of flux and conductive agent to refractory oxide base materials (such as MgO, CaO, Al2O3, etc.). The flux component weakens the strong bonds in the refractory oxide lattice, allowing the system to preferentially form a continuous liquid phase in the eutectic region at a lower temperature. This liquid phase has good fluidity, can encapsulate and promote the gradual melting of the remaining solid phase, thereby significantly reducing the complete melting temperature of the refractory oxide and lowering the melting threshold. The conductive agent component improves the conductivity of the material in the solid or partially molten state, allowing current to pass through the material and generate Joule heat in the early stages of heating, promoting the material's internal heating and melting. As the liquid phase gradually appears, the mobile ions dissociated from the conductive agent further enhance the ion migration ability of the molten state, improve current distribution and heat and mass transfer efficiency, and accelerate the formation of a stable and uniform conductive molten pool.

[0012] Based on the above, the synergistic effect of conductive agents and fluxes effectively solves the technical problems of poor conductivity, slow molten pool formation and high energy consumption of refractory oxides in the prior art, and realizes the rapid formation of a stable conductive molten pool under low current.

[0013] This invention provides a method for forming a molten pool of low-conductivity refractory oxides, comprising the steps of: Obtain the composite furnace charge as described above; The composite charge is placed in an electric furnace and heated until completely melted to form a molten pool.

[0014] Furthermore, the temperature at which complete melting occurs is 2000-2700°C.

[0015] The method for forming a low-conductivity refractory oxide molten pool provided by the present invention, by using the composite charge as described above and heating it in an electric furnace until completely melted, has the following beneficial effects: This invention is simple to operate. It only requires loading the composite furnace charge into the electric melting furnace and heating it according to the conventional heating procedure. No equipment modification or auxiliary heating means are required.

[0016] This invention utilizes the existing low melting point and initial conductivity of composite furnace charge to rapidly form a continuous and stable conductive molten pool at a lower current, thus avoiding local overheating.

[0017] This invention is applicable to various electric melting furnaces such as electric arc furnaces and transfer plasma furnaces, and has strong industrial applicability.

[0018] This invention provides a method for reducing low-conductivity refractory oxides, comprising the following steps: A molten pool is formed using the method described above; A solid reducing agent is added to the molten pool or a gaseous reducing agent is introduced into the reaction environment to carry out a molten reduction reaction and obtain a reduction product.

[0019] Furthermore, the temperature of the melt reduction reaction is 2000-2700℃, and the duration is 40-100min.

[0020] The reduction method for low-conductivity refractory oxides provided by this invention, which further adds a reducing agent for melt reduction after a stable molten pool is formed, has the following beneficial effects: In this invention, the molten pool has good electrical conductivity and fluidity. After the reducing agent is added, it can be quickly dispersed and fully contacted with the oxide, resulting in excellent mass and heat transfer conditions and shortening the reduction reaction time.

[0021] The present invention carries out the reduction reaction in the range of 2000-2700℃, and the temperature can be flexibly adjusted according to different target products (such as metallic magnesium, ferrosilicon alloy, etc.) to balance the reduction rate and energy consumption.

[0022] The uniform molten pool temperature and stable current path in this invention help the reduction reaction proceed smoothly, reduce side reactions, and improve the yield and purity of metals or alloys. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 This is a photograph of the composite furnace charge in Embodiment 1 of the present invention, showing the start of melting at a current of 55A.

[0025] Figure 2 This is a photograph of the composite furnace charge completely melted under a current of 122A in Embodiment 1 of the present invention.

[0026] Figure 3 This is a photograph of the composite furnace charge in Embodiment 2 of the present invention, showing the charge beginning to melt at a current of 49A.

[0027] Figure 4 This is a photograph of the composite furnace charge completely melted at a current of 97A in Example 2 of the present invention.

[0028] Figure 5 This is the pseudo-ternary phase diagram of the composite furnace charge based on mass ratio in Embodiment 3 of the present invention.

[0029] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0030] 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 a part of the embodiments of the present invention, and not all of them. 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.

[0031] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0032] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of the invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to the methods, devices, and materials in the embodiments of the present invention.

[0033] This invention provides a composite charge for forming a low-conductivity refractory oxide molten pool in an electric melting furnace. The composite charge includes a refractory oxide base material, a flux, and a conductive agent. The conductive agent accounts for 3-7% of the mass fraction of the composite charge, and the mass ratio of the refractory oxide base material to the flux is 1:0.72-1.56. The refractory oxide base material includes magnesium oxide, calcium oxide, and aluminum oxide.

[0034] For example, the mass fraction of the conductive agent in the composite charge can be 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, and each of these minimum and maximum values, or a range of any two values.

[0035] For example, the mass ratio of the refractory oxide base material to the flux can be 1:0.72, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.56, and each of these minimum and maximum values, or a range of any two ratios.

[0036] The role of the conductive agent in this invention is as follows: In the initial heating stage, the conductivity of the solid / semi-molten state is improved, and Joule heating is initiated. During the melting process, the resistance is reduced, enhancing the stability of the current path. After the molten state is formed, the ions dissociate, enhancing the migration ability of molten ions. In addition, the conductive agent can work synergistically with the flux, forming a complementary function between the conductive agent and the flux to achieve rapid pooling with low current.

[0037] This invention limits the mass fraction of the conductive agent in the composite charge to 3-7%. When the mass fraction of the conductive agent in the composite charge is less than 3%, the solid conductivity of the system is not sufficiently improved in the early stage of heating, making it difficult to establish a stable current path in time. This leads to an increase in the initial melting current and the complete melting current, and a slower rate of molten pool formation. When the mass fraction of the conductive agent in the composite charge is greater than 7%, the excessive conductive agent will dilute the optimal eutectic ratio of the refractory oxide base material and the flux, and is prone to increased volatilization loss and the risk of introducing impurities. This is not conducive to further reducing the complete melting temperature and may have an adverse effect on product purity and economy.

[0038] In this invention, the role of the flux is to lower the liquidus formation temperature of refractory oxides and promote the preferential formation of the eutectic liquid phase. Specifically, after the flux enters the refractory oxide lattice, it weakens the strong ionic bonds in the base materials such as MgO, CaO, and alumina, disrupting the stability of the high-melting-point solid structure, allowing the system to form a continuous liquid phase in the eutectic composition region at a lower temperature. This liquid phase has good fluidity and wettability, enabling it to encapsulate and promote the gradual melting of the remaining solid phase, thereby significantly reducing the complete melting temperature (e.g., from above 2850℃ for pure MgO to 2000-2700℃). Simultaneously, the eutectic liquid phase formed by the flux also provides a medium environment for the ion dissociation and migration of the conductive agent, synergistically achieving rapid low-current cell formation with the conductive agent.

[0039] This invention limits the mass ratio of refractory oxide base material to flux to 1:0.72-1.56. When the mass ratio of refractory oxide base material to flux is less than 1:0.72, the amount of flux added is insufficient, making it difficult to effectively adjust the system composition to the low liquidus region, which is not conducive to the preferential formation of continuous liquid phase, resulting in an increase in the complete melting temperature and slow formation of the molten pool. When the mass ratio of refractory oxide base material to flux is greater than 1:1.56, the amount of flux added is too high, and the system will deviate from the preferred composition range of the target refractory oxide base material, resulting in an increase in the proportion of slag phase in the molten pool, an increase in volatilization loss and the risk of impurity introduction, and may adversely affect product purity, yield and economy.

[0040] In some embodiments, the refractory oxide base material comprises magnesium oxide. In some embodiments, the magnesium oxide accounts for 35-55% of the mass fraction in the composite charge.

[0041] For example, the mass fraction of magnesium oxide in the composite furnace charge can be 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, and each of these minimum and maximum values, or a range of any two values.

[0042] In some embodiments, the flux includes at least one of CaO, SiO2, P2O5, TiO2, Al2O3, and Fe2O3.

[0043] In some embodiments, the conductive agent includes a fluoride; more specifically, the conductive agent includes at least one of sodium fluoride, calcium fluoride, magnesium fluoride, and cryolite.

[0044] This invention designs additive systems based on the eutectic principle and phase diagram theory. Specifically, it involves using Factsage thermodynamic calculation software to calculate ternary and pseudo-ternary phase diagrams, focusing on analyzing the distribution region of the liquidus line at 2400℃, and then progressively screening out binary, ternary, or quaternary additive systems and their optimal proportions in the low liquidus temperature region. This method allows for targeted identification of eutectic component regions, improving formulation design efficiency and repeatability, and avoiding the blind reliance on empirical ingredient formulation.

[0045] Based on this, the present invention provides various flux systems (including P2O5-SiO2-CaO quaternary system, P2O5-SiO2 ternary system, SiO2-TiO2-CaO quaternary system, P2O5 binary system, SiO2-TiO2 ternary system, Al2O3-SiO2-CaO ternary system, Al2O3-SiO2 ternary system, SiO2 binary system, and Al2O3 binary system) and their proportions with magnesium oxide. By changing the type and proportion of flux, the complete melting temperature of the composite furnace charge can be systematically controlled within a wide range of 2000℃ to 2700℃, thereby adapting to the diverse requirements of different refractory oxide base materials, different electric furnace operating conditions, and subsequent reduction processes for the molten pool temperature, significantly improving the industrial applicability, flexibility, and repeatability of the present invention.

[0046] Specifically: In some embodiments, when the flux in the composite charge is composed of P2O5, SiO2, and CaO, and the mass ratio of MgO, P2O5, SiO2, and CaO is 4.5-6:4:2:1, the complete melting temperature of the composite charge is 2000-2100℃. When the flux of the composite furnace charge is composed of P2O5 and SiO2, and the mass ratio of MgO, P2O5 and SiO2 is 5-7:5:2, or when the flux of the composite furnace charge is composed of SiO2, TiO2 and CaO, and the mass ratio of MgO, SiO2, TiO2 and CaO is 9-11:6:3:1, the complete melting temperature of the composite furnace charge is 2100-2200℃. When the flux of the composite furnace charge is P2O5 and the mass ratio of MgO to P2O5 is 8-10:8, or when the flux of the composite furnace charge is composed of SiO2 and TiO2 and the mass ratio of MgO, SiO2, and TiO2 is 5-7:5:2, or when the flux of the composite furnace charge is composed of Al2O3, SiO2, and CaO and the mass ratio of MgO:Al2O3:SiO2:CaO is 8-10:8:3:1, the complete melting temperature of the composite furnace charge is 2200-2300℃. When the flux of the composite furnace charge is composed of Al2O3 and SiO2, and the mass ratio of MgO, Al2O3 and SiO2 is 2-4:2:1, the complete melting temperature of the composite furnace charge is 2300-2400℃. When the flux of the composite furnace charge is SiO2 and the mass ratio of MgO to SiO2 is 4-5.5:4, the complete melting temperature of the composite furnace charge is 2400-2500℃. When the flux of the composite furnace charge is Al2O3 and the mass ratio of MgO to Al2O3 is 4-5.5:4, the complete melting temperature of the composite furnace charge is 2600-2700℃.

[0047] Building upon the aforementioned wide-range control, this invention further discovers that by finely adjusting the proportions of each component, the fluctuation range of the complete melting temperature can be further narrowed, enabling precise control of the melting temperature. Specifically: In some embodiments, when the flux in the composite charge is composed of P2O5, SiO2, and CaO, and the mass ratio of MgO, P2O5, SiO2, and CaO is 4.5-5.5:4:2:1, the complete melting temperature of the composite charge is 2050-2070°C. When the flux of the composite furnace charge is composed of P2O5 and SiO2, and the mass ratio of MgO, P2O5 and SiO2 is 5.5-6.5:5:2, the complete melting temperature of the composite furnace charge is 2130-2150℃. When the flux of the composite furnace charge is composed of SiO2, TiO2, and CaO, and the mass ratio of MgO, SiO2, TiO2, and CaO is 9.5-10.5:6:3:1, the complete melting temperature of the composite furnace charge is 2170-2190℃.

[0048] In some embodiments, when the flux of the composite charge is P2O5 and the mass ratio of MgO to P2O5 is 8.5-9.5:8, the complete melting temperature of the composite charge is 2200-2220°C. When the flux of the composite furnace charge is composed of SiO2 and TiO2, and the mass ratio of MgO, SiO2 and TiO2 is 5.5-6.5:5:2, the complete melting temperature of the composite furnace charge is 2240-2260℃. When the flux of the composite furnace charge is composed of Al2O3, SiO2, and CaO, and the mass ratio of MgO:Al2O3:SiO2:CaO is 8.5-9.5:8:3:1, the complete melting temperature of the composite furnace charge is 2270-2290℃. When the flux of the composite furnace charge is composed of Al2O3 and SiO2, and the mass ratio of MgO, Al2O3 and SiO2 is 2.5-3.5:2:1, the complete melting temperature of the composite furnace charge is 2300-2320℃. When the flux of the composite furnace charge is SiO2 and the mass ratio of MgO to SiO2 is 4.5-5.5:4, the complete melting temperature of the composite furnace charge is 2410-2430℃. When the flux of the composite furnace charge is Al2O3 and the mass ratio of MgO to Al2O3 is 4.5-5.5:4, the complete melting temperature of the composite furnace charge is 2660-2680℃.

[0049] It should be noted that the lower the complete melting temperature, the lower the initial melting current and the complete melting current. This is because a lower complete melting temperature means that the system can form a continuous liquid phase at a lower temperature. The presence of the conductive agent allows this liquid phase to have good conductivity at a lower temperature, thereby establishing a stable electrical path between the electrode and the material with a smaller applied current, generating sufficient Joule heat to maintain and accelerate the melting process. In other words, the complete melting temperature is a physical quantity characterizing the intrinsic melting properties of a material. The lower its value, the smaller the required initial melting current and complete melting current under the same electric furnace conditions, and the faster the molten pool forms.

[0050] For example, when the complete melting temperature is 2000-2100°C, the initial melting current is 30-40A, and the complete melting current is 70-80A. When the complete melting temperature is 2100-2200℃, the initial melting current is 40-45A, and the complete melting current is 85-90A. When the complete melting temperature is 2200-2300℃, the initial melting current is 40-50A, and the complete melting current is 90-95A. When the complete melting temperature is 2300-2400℃, the initial melting current is 45-50A, and the complete melting current is 95-100A. When the complete melting temperature is 2400-2500℃, the initial melting current is 50-55A, and the complete melting current is 100-110A. When the complete melting temperature is 2500-2600℃, the initial melting current is 55-60A, and the complete melting current is 120-130A.

[0051] It should be noted that the above current values ​​are relative comparison values ​​measured under specific small-scale test conditions (material dosage approximately 1.4-2.8g, electrode spacing and output characteristics of the electric melting furnace are fixed). In actual industrial applications, as the amount of composite charge increases (e.g., from gram-level to ton-level), parameters such as electrode size, furnace structure, and power supply capacity will change accordingly, and the absolute current value will increase significantly proportionally (e.g., the current in industrial electric fused magnesia furnaces can reach thousands of amperes). However, the complete melting temperature, as an intrinsic property of the material, does not change with the scale of the material. Therefore, using the complete melting temperature as the core indicator to characterize the melting performance of composite charges is more universal and stable than the absolute current value. This invention clearly defines the complete melting temperature range (2000-2700℃) corresponding to different flux systems, and further refines it to a narrow window of ±10℃, precisely to provide a reliable low pooling threshold basis unaffected by scale during industrial scale-up.

[0052] In summary, by significantly reducing the complete melting temperature (from over 2850℃ for pure MgO to 2000-2700℃), this invention ensures in principle that a continuous, stable, and conductive molten pool can be rapidly formed in an electric furnace of any size with a relatively lower current (compared to pure MgO or conventional furnace charge), thereby achieving an energy-saving, efficient, and uniform melting process.

[0053] In some embodiments, the preparation of the composite furnace charge includes the following steps: The refractory oxide base material, flux, and conductive agent are sequentially mixed and molded to obtain the composite furnace charge; The mixing process includes ball milling, wherein the mixing speed of the ball milling is 100-300 rpm and the ball milling time is 5-20 min; The forming process includes tableting. In some embodiments, the tableting time can be 10-20 minutes.

[0054] The present invention also provides a method for forming a molten pool of low-conductivity refractory oxide, comprising the steps of: Obtain the composite furnace charge as described above; The composite charge is placed in an electric furnace and heated until completely melted to form a molten pool.

[0055] In some embodiments, the complete melting temperature is 2000-2700℃. The complete melting temperature is the same as the complete melting temperature corresponding to the aforementioned composite charge, and its range of 2000-2700℃ covers the specific temperature range under different flux systems in each embodiment. The temperature value is adjustable as the composition of the composite charge changes.

[0056] In some more specific embodiments, the heating to form a molten pool is specifically performed by placing the composite charge in an electric furnace and gradually increasing the current from 30A to 150A, with each step increasing by 1A. Here, "beginning to melt" refers to the appearance of a continuous liquid phase at the edge or in a localized area of ​​the sample; "complete melting" refers to the formation of a continuous melt throughout the sample with no obvious unmelted solid residue. By recording the material state under different currents, the effectiveness of different additive systems in lowering the melting threshold and promoting molten pool formation can be verified.

[0057] In some embodiments, an electric melting furnace refers to a heating device that converts electrical energy into heat energy to melt materials. Its core function lies in utilizing the current path established between the electrodes and the material to generate Joule heating and / or arc heating or plasma heating. The electric melting furnace includes, but is not limited to, electric arc furnaces, transfer plasma furnaces, electroslag furnaces, and resistance arc combined furnaces. Those skilled in the art will understand that any furnace type that inputs electrical energy through electrodes and can form a current path in the material to achieve heating and melting can be applied to this invention.

[0058] In some embodiments, the transfer plasma furnace includes a plasma reaction vessel, a transfer arc plasma torch, an anode crucible, and an inlet / outlet gas balancing device. The transfer arc plasma torch is disposed on the plasma reaction vessel, with its cathode extending into the inner cavity of the plasma reaction vessel; the anode crucible is disposed inside the plasma reaction vessel, opposite to the cathode, and serves as the anode of the transfer arc, connected to the positive terminal of an external power supply. During operation, a conductive path is formed between the cathode and the anode crucible. This conductive path is closed by the conductive components in the furnace charge and the plasma gas (such as argon, helium, nitrogen, etc.), causing the inert gas to plasmaize and form a high-temperature plasma jet that bombards the surface of the furnace charge. Simultaneously, current directly passes through the furnace charge, generating Joule heat, thus forming a dual heating mechanism.

[0059] This invention provides a method for reducing low-conductivity refractory oxides, comprising the following steps: A molten pool is formed using the method described above; A reducing agent is added to the molten pool to carry out a molten reduction reaction, thereby obtaining a reduction product.

[0060] In some embodiments, the reducing agent includes carbonaceous reducing agents (such as graphite, coke, pulverized coal, etc.) and / or siliceous reducing agents (such as ferrosilicon, elemental silicon, etc.). The amount of reducing agent added can be adjusted according to the target product and oxide content. For example, the amount of reducing agent added is 10-15% of the total mass of the composite furnace charge.

[0061] In some embodiments, the temperature of the melt reduction reaction is 2000-2700°C, consistent with the aforementioned range of complete melting temperature of the composite charge. The reaction time depends on the material scale and the type of reducing agent; for example, the reaction time is 30-90 minutes.

[0062] It should be noted that, because the molten pool formed by this invention has a low complete melting temperature (2000-2700℃) and good electrical conductivity, after the addition of a reducing agent, the molten pool can maintain a stable current path and a uniform temperature distribution, which is conducive to the rapid and complete progress of the reduction reaction and improves the yield of metals or alloys. At the same time, the presence of flux in the molten pool can also reduce the viscosity of the slag, improve the slag-metal separation effect, and further improve the purity of the product.

[0063] To facilitate a further understanding of the present invention by those skilled in the art, the following examples are provided: Example 1 Based on the phase diagram calculation results, the composite furnace charge is obtained.

[0064] The total mass of the composite furnace charge was set at 8g, so 4.22g of MgO raw material, 3.38g of Al2O3 as flux, and 0.40g of sodium fluoride as conductive agent were used. The mass ratio of MgO raw material (refractory oxide base) to Al2O3 flux in the composite furnace charge was approximately 5:4. Sodium fluoride, as a conductive agent, was fixed at 5% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into tablets for 10 minutes to obtain the composite furnace charge.

[0065] 1.438g of composite furnace charge was placed in an electric arc furnace and heated at a current of 40A, with the current increased by 1A each time for observation. The final melting current was 55A, and the initial melting temperature was 1770℃. The complete melting current was 122A, and the complete melting temperature was 2670℃. A photograph of the composite furnace charge at the point of initial melting at 55A is shown in this example. Figure 1As shown; in this embodiment, a physical image of the composite furnace charge completely melted under a current of 122A is shown. Figure 2 As shown.

[0066] Example 2 Based on the phase diagram calculation results, the composite furnace charge is obtained.

[0067] The total mass of the composite furnace charge was set at 8g. Therefore, 3.80g of MgO raw material, 2.53g of Al2O3 and 1.27g of SiO2 as fluxes, and 0.40g of sodium fluoride as a conductive agent were used. The mass ratio of MgO raw material (refractory oxide base) to flux (Al2O3 and SiO2) in the composite furnace charge was approximately 3:2:1. Sodium fluoride, as a conductive agent, was fixed at 5% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into tablets for 10 minutes to obtain the composite furnace charge.

[0068] 2.8326g of the composite charge was placed into the electric arc furnace. Heating was started at a current of 40A, with the current increased by 1A each time for observation. The final melting current was 49A, and the initial melting temperature was 1720℃. The complete melting current was 97A, and the complete melting temperature was 2310℃. A photograph of the composite charge at the point of initial melting at 49A is shown in this embodiment. Figure 3 As shown; in this embodiment, a physical image of the composite furnace charge completely melted under a current of 97A is shown. Figure 4 As shown.

[0069] Example 3 According to the calculation results of the phase diagram, such as Figure 5 To obtain composite furnace charge.

[0070] The total mass of the composite furnace charge was set at 8g. Therefore, 3.26g of MgO raw material was used, and 2.89g, 1.09g, and 0.36g of Al2O3, SiO2, and CaO were used as fluxes, respectively. 0.40g of sodium fluoride was used as the conductive agent. The mass ratio of MgO raw material to fluxes Al2O3, SiO2, and CaO in the composite furnace charge was approximately 9:8:3:1. Sodium fluoride was added as a conductive agent, with its content fixed at 5% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into sheets for 10 minutes to obtain the composite furnace charge.

[0071] 2.3868g of composite charge was placed into the furnace. Heating was started at a current of 40A, with the current increased by 1A each time for observation. The final melting current was 45A, and the initial melting temperature was 1690℃. The complete melting current was 95A, and the complete melting temperature was 2280℃.

[0072] Example 4 Based on the phase diagram calculation results, the composite furnace charge is obtained.

[0073] The total mass of the composite furnace charge was set at 8g, so 4.02g of MgO raw material, 3.58g of P2O5 as flux, and 0.40g of sodium fluoride as conductive agent were used. The mass ratio of MgO raw material to P2O5 flux in the composite furnace charge was approximately 9:8, and sodium fluoride was added as a conductive agent, with its content fixed at 5% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into tablets for 10 minutes to obtain the composite furnace charge.

[0074] 1.937g of composite charge was placed into the electric arc furnace. Heating was started at a current of 40A, with the current increased by 1A each time for observation. The final melting current was 43A, the initial melting temperature was 1670℃, the complete melting current was 90A, and the complete melting temperature was 2210℃.

[0075] Example 5 Based on the phase diagram calculation results, the composite furnace charge is obtained.

[0076] The total mass of the composite furnace charge was set at 8g. Therefore, 3.51g of MgO raw material, 2.92g of P2O5 and 1.17g of SiO2 as fluxes, and 0.40g of sodium fluoride as a conductive agent were used. The mass ratio of MgO raw material to fluxes P2O5 and SiO2 in the composite furnace charge was approximately 6:5:2. Sodium fluoride was added as a conductive agent, with its content fixed at 5% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into sheets for 10 minutes to obtain the composite furnace charge.

[0077] 2.6653g of the composite charge was placed into the furnace. Heating was started at a current of 40A, with the current increased by 1A each time for observation. The final melting current was 41A, and the initial melting temperature was 1660℃. The complete melting current was 85A, and the complete melting temperature was 2140℃.

[0078] Example 6 Based on the phase diagram calculation results, the composite furnace charge is obtained.

[0079] The total mass of the composite furnace charge was set at 8g. Therefore, 3.17g of MgO raw material was used, and 2.53g, 1.27g, and 0.63g of P2O5, SiO2, and CaO were used as fluxes, respectively. 0.40g of sodium fluoride was used as the conductive agent. The mass ratio of MgO raw material to fluxes P2O5, SiO2, and CaO in the composite furnace charge was approximately 5:4:2:1. Sodium fluoride was added as a conductive agent, with its content fixed at 5% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into sheets for 10 minutes to obtain the composite furnace charge.

[0080] 2.7384g of composite charge was placed into the furnace. Heating was started at a current of 35A, with the current increased by 1A each time for observation. The final melting current was 39A, and the initial melting temperature was 1640℃. The complete melting current was 80A, and the complete melting temperature was 2060℃.

[0081] Example 7 Based on the phase diagram calculation results, the composite furnace charge is obtained.

[0082] The total mass of the composite furnace charge was set at 8g, so 4.22g of MgO raw material, 3.38g of SiO2 as flux, and 0.40g of sodium fluoride as conductive agent were used. The mass ratio of MgO raw material to SiO2 flux was determined to be approximately 5:4, and sodium fluoride was added as a conductive agent, with its content fixed at 5% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into sheets for 10 minutes to obtain the composite furnace charge.

[0083] 1.575g of composite furnace charge was placed into the electric arc furnace. Heating was started at a current of 40A, with the current increased by 1A each time for observation. The final melting current was 52A, the initial melting temperature was 1750℃, the complete melting current was 105A, and the complete melting temperature was 2420℃.

[0084] Example 8 Based on the phase diagram calculation results, the composite furnace charge is obtained.

[0085] The total mass of the composite furnace charge was set at 8g. Therefore, 3.51g of MgO raw material, 2.92g of SiO2 and 1.17g of TiO2 as fluxes, and 0.40g of sodium fluoride as a conductive agent were used. The mass ratio of MgO raw material to fluxes SiO2 and TiO2 was determined to be approximately 6:5:2. Sodium fluoride was added as a conductive agent, with its content fixed at 5% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into sheets for 10 minutes to obtain the composite furnace charge.

[0086] 2.3951g of composite charge was placed into the electric arc furnace. Heating was started at a current of 40A, with the current increased by 1A each time for observation. The final melting current was 47A, the initial melting temperature was 1710℃, the complete melting current was 93A, and the complete melting temperature was 2250℃.

[0087] Example 9 Based on the phase diagram calculation results, the composite furnace charge is obtained.

[0088] The total mass of the composite furnace charge was set at 8g. Therefore, 3.80g of MgO raw material was used, and 2.28g, 1.14g, and 0.38g of SiO2, TiO2, and CaO were used as fluxes, respectively. 0.40g of sodium fluoride was used as the conductive agent. The mass ratio of MgO raw material to fluxes SiO2, TiO2, and CaO was determined to be approximately 10:6:3:1. Sodium fluoride was added as a conductive agent, with its content fixed at 5% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into sheets for 10 minutes to obtain the composite furnace charge.

[0089] 2.5374g of composite charge was placed into the electric arc furnace. Heating was started at a current of 40A, with the current increased by 1A each time for observation. The final melting current was 43A, and the initial melting temperature was 1670℃. The complete melting current was 88A, and the complete melting temperature was 2180℃.

[0090] To more clearly illustrate the effectiveness of this invention in solving the technical problem of poor conductivity and mismatch between strong electric field and MgO material in an electric arc furnace heating scenario, the relationships between different flux types, corresponding formulations, and melting currents are summarized in Table 1. Test results show that by using a flux system design based on phase diagram calculations and incorporating a fixed proportion of sodium fluoride conductive agent, the melting current and complete melting temperature of the MgO system are significantly reduced.

[0091] Table 1. MgO to flux ratio, melting current, and corresponding temperature results in different embodiments. Example 10 This embodiment provides a method for reducing low-conductivity refractory oxides, using the composite furnace charge prepared in Example 1 for molten reduction.

[0092] Obtain the composite furnace charge prepared in Example 1.

[0093] 1.438g of the composite furnace charge was placed in an electric melting furnace and heated starting at a current of 40A, with the current increased by 1A each time. Heating continued until completely melted, forming a continuous and stable conductive molten pool. In this embodiment, the complete melting current was 122A, and the complete melting temperature was 2670℃.

[0094] A reducing agent (graphite powder) is added to the formed molten pool, with the amount of reducing agent being 12% of the total mass of the composite furnace charge. The reaction is maintained at a molten state for 60 minutes, with the complete melting temperature above the reaction temperature. During the reaction, magnesium vapor escapes from the molten pool and is collected by a condensation and collection device to obtain magnesium products, while the reaction residue is discharged from the slag discharge port.

[0095] The magnesium reduction rate in this example was 72%, and the purity of the resulting magnesium product was 93%.

[0096] The results show that the molten pool formed by the composite charge of the present invention has good conductivity and fluidity, and can carry out a high-efficiency melting reduction reaction after the addition of a reducing agent, thereby obtaining a high reduction rate and product purity.

[0097] Comparative Example 1 The MgO raw material was ball-milled and pressed under the same conditions. MgO samples of the same mass as in Example 1 were placed in a furnace and heated at a current of 40 A, with the current increased by 1 A at each step for observation. The results showed that the pure MgO sample began to partially melt at 90 A, with the initial melting temperature at 2210 °C. When the current was further increased to 150 A, the sample still had not completely melted at 2900 °C.

[0098] Test results show that, compared with the system after adding additives in the forward embodiment, the initial melting current and complete melting current of the pure MgO sample are significantly increased, indicating that without additives, the system is difficult to quickly enter the low liquidus region and is also difficult to form a stable conductive path in a timely manner.

[0099] Comparative Example 2 Compared to Example 1, all other conditions remain unchanged in this comparative example, except that the mass fraction of the conductive agent in the composite charge is adjusted to below 3%, specifically 2%.

[0100] The total mass of the composite furnace charge was set at 8g, so 4.36g of MgO raw material, 3.48g of Al2O3 as flux, and 0.16g of sodium fluoride as conductive agent were used. The mass ratio of MgO raw material (refractory oxide base) to Al2O3 flux in the composite furnace charge was approximately 5:4. Sodium fluoride, as a conductive agent, was fixed at 2% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into tablets for 10 minutes to obtain the composite furnace charge.

[0101] 1.438g of composite furnace charge was placed in an electric arc furnace and heated at a current of 40A. The current was increased by 1A each time for observation. The final melting current was 60A, the initial melting temperature was 1840℃, the complete melting current was 136A, and the complete melting temperature was 2810℃.

[0102] Comparative Example 3 Compared to Example 1, all other conditions remain unchanged in this comparative example, except that the mass fraction of the conductive agent in the composite charge is adjusted to more than 7%, specifically 8%.

[0103] The total mass of the composite furnace charge was set at 8g, so 4.09g of MgO raw material, 3.27g of Al2O3 as flux, and 0.64g of sodium fluoride as conductive agent were used. The mass ratio of MgO raw material (refractory oxide base) to Al2O3 flux in the composite furnace charge was approximately 5:4. Sodium fluoride, as a conductive agent, had a fixed content of 8% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into tablets for 10 minutes to obtain the composite furnace charge.

[0104] 1.438g of composite furnace charge was placed in an electric arc furnace and heated at a current of 40A. The current was increased by 1A each time for observation. The final melting current was 57A, the melting temperature was 1800℃, the complete melting current was 128A, and the complete melting temperature was 2730℃.

[0105] Comparative Example 4 Compared to Example 1, the other conditions in this comparative example remain unchanged, except that the mass ratio of refractory oxide base material to flux is adjusted to 1:0.72-1.56 or higher, specifically 1:1.6.

[0106] The total mass of the composite furnace charge was set at 8g, so 2.92g of MgO raw material, 4.68g of Al2O3 as flux, and 0.40g of sodium fluoride as conductive agent were used. The mass ratio of MgO raw material (refractory oxide base) to Al2O3 flux in the composite furnace charge was approximately 1:1.6. Sodium fluoride, as a conductive agent, had a fixed content of 5% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into tablets for 10 minutes to obtain the composite furnace charge.

[0107] 1.438g of composite furnace charge was placed in an electric arc furnace and heated at a current of 40A. The current was increased by 1A each time for observation. The final melting current was 60A, the initial melting temperature was 1870℃, the complete melting current was 135A, and the complete melting temperature was 2790℃.

[0108] Comparative Example 5 Compared to Example 1, the other conditions in this comparative example remain unchanged, except that the mass ratio of refractory oxide base material to flux is adjusted to below 1:0.72-1.56, specifically 1:0.7.

[0109] The total mass of the composite furnace charge was set at 8g, so 4.47g of MgO raw material, 3.13g of Al2O3 as flux, and 0.40g of sodium fluoride as conductive agent were used. The mass ratio of MgO raw material (refractory oxide base) to Al2O3 flux in the composite furnace charge was approximately 1:0.7. Sodium fluoride, as a conductive agent, had a fixed content of 5% of the total mass. The refractory oxide raw material, flux, and conductive agent were ball-milled for 20 minutes at a mixing speed of 200 rpm. After uniform mixing, the precursor mixture was pressed into tablets for 10 minutes to obtain the composite furnace charge.

[0110] 1.438g of composite furnace charge was placed in an electric arc furnace and heated at a current of 40A. The current was increased by 1A each time for observation. The final melting current was 63A, the melting temperature was 1900℃, the complete melting current was 142A, and the complete melting temperature was 2890℃.

[0111] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A composite furnace charge for forming a low-conductivity refractory oxide molten pool in an electric melting furnace, characterized in that, The composite furnace charge includes a refractory oxide base material, a flux, and a conductive agent. The conductive agent accounts for 3-7% of the mass fraction of the composite furnace charge, and the mass ratio of the refractory oxide base material to the flux is 1:0.72-1.

56. The refractory oxide base material includes at least one of magnesium oxide, calcium oxide, and aluminum oxide.

2. The composite furnace charge according to claim 1, characterized in that, The refractory oxide base material includes magnesium oxide; The flux includes at least one of CaO, SiO2, P2O5, TiO2, Al2O3, and Fe2O3; The conductive agent includes fluorides.

3. The composite furnace charge according to claim 1, characterized in that, The refractory oxide base material is magnesium oxide; When the flux in the composite charge is composed of P2O5, SiO2, and CaO, and the mass ratio of MgO, P2O5, SiO2, and CaO is 4.5-6:4:2:1, the complete melting temperature of the composite charge is 2000-2100℃. When the flux in the composite furnace charge is composed of P2O5 and SiO2, and the mass ratio of MgO, P2O5, and SiO2 is 5-7:5:2; or when the flux in the composite furnace charge is composed of SiO2, TiO2, and CaO, and the mass ratio of MgO, SiO2, TiO2, and CaO is 9-11:6:3:1, the complete melting temperature of the composite furnace charge is 2100-2200℃. When the flux in the composite furnace charge is P2O5, and the mass ratio of MgO to P2O5 is 8-10:8; or, the flux in the composite furnace charge is composed of SiO2 and TiO2, and the mass ratio of MgO, SiO2, and TiO2 is 5-7:5:2; or, the flux in the composite furnace charge is composed of Al2O3, SiO2, and CaO, and the mass ratio of MgO:Al2O3:SiO2:CaO is 8-10:8:3:1, the complete melting temperature of the composite furnace charge is 2200-2300℃. When the flux in the composite furnace charge is composed of Al2O3 and SiO2, and the mass ratio of MgO, Al2O3 and SiO2 is 2-4:2:1, the complete melting temperature of the composite furnace charge is 2300-2400℃. When the flux in the composite charge is SiO2 and the mass ratio of MgO to SiO2 is 4-5.5:4, the complete melting temperature of the composite charge is 2400-2500℃. When the flux in the composite charge is Al2O3 and the mass ratio of MgO to Al2O3 is 4-5.5:4, the complete melting temperature of the composite charge is 2600-2700℃.

4. The composite furnace charge according to claim 1, characterized in that, The refractory oxide base material is magnesium oxide; When the flux in the composite charge is composed of P2O5, SiO2, and CaO, and the mass ratio of MgO, P2O5, SiO2, and CaO is 4.5-5.5:4:2:1, the complete melting temperature of the composite charge is 2050-2070℃. When the flux in the composite furnace charge is composed of P2O5 and SiO2, and the mass ratio of MgO, P2O5 and SiO2 is 5.5-6.5:5:2, the complete melting temperature of the composite furnace charge is 2130-2150℃. When the flux in the composite furnace charge is composed of SiO2, TiO2, and CaO, and the mass ratio of MgO, SiO2, TiO2, and CaO is 9.5-10.5:6:3:1, the complete melting temperature of the composite furnace charge is 2170-2190℃.

5. The composite furnace charge according to claim 1, characterized in that, The refractory oxide base material is magnesium oxide; When the flux in the composite furnace charge is P2O5 and the mass ratio of MgO to P2O5 is 8.5-9.5:8, the complete melting temperature of the composite furnace charge is 2200-2220℃. When the flux in the composite furnace charge is composed of SiO2 and TiO2, and the mass ratio of MgO, SiO2, and TiO2 is 5.5-6.5:5:2, the complete melting temperature of the composite furnace charge is 2240-2260℃. When the flux in the composite furnace charge is composed of Al2O3, SiO2, and CaO, and the mass ratio of MgO:Al2O3:SiO2:CaO is 8.5-9.5:8:3:1, the complete melting temperature of the composite furnace charge is 2270-2290℃. When the flux in the composite furnace charge is composed of Al2O3 and SiO2, and the mass ratio of MgO, Al2O3 and SiO2 is 2.5-3.5:2:1, the complete melting temperature of the composite furnace charge is 2300-2320℃. When the flux in the composite charge is SiO2 and the mass ratio of MgO to SiO2 is 4.5-5.5:4, the complete melting temperature of the composite charge is 2410-2430℃. When the flux in the composite charge is Al2O3 and the mass ratio of MgO to Al2O3 is 4.5-5.5:4, the complete melting temperature of the composite charge is 2660-2680℃.

6. The composite furnace charge according to claim 1, characterized in that, The preparation of the composite furnace charge includes the following steps: The refractory oxide base material, the flux, and the conductive agent are sequentially mixed and molded to obtain the composite furnace charge; The mixing process includes ball milling; The molding process includes tableting.

7. A method for forming a molten pool of low-conductivity refractory oxides, characterized in that, Including the following steps: Obtain the composite furnace charge as described in any one of claims 1-6; The composite charge is placed in an electric furnace and heated until completely melted to form a molten pool.

8. The method for forming a low-conductivity refractory oxide molten pool according to claim 7, characterized in that, The temperature at which complete melting occurs is 2000-2700℃.

9. A method for reducing a low-conductivity refractory oxide, characterized in that, Including the following steps: A molten pool is formed using the method described in claim 7 or 8; A solid reducing agent is added to the molten pool or a gaseous reducing agent is introduced into the reaction environment to carry out a molten reduction reaction and obtain a reduction product.

10. The method for reducing low-conductivity refractory oxides according to claim 9, characterized in that, The melting reduction reaction is carried out at a temperature of 2000-2700℃ for a duration of 40-100 min.

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