Composite material for magnesium smelting and preparation method and application thereof

Abstract

The invention relates to the technical field of magnesium smelting, in particular to a composite material for magnesium smelting and a preparation method and application thereof. The raw materials of the composite material comprise a magnesium-containing particle material, a heat-conducting filler and a heat-conducting adhesive, the mass ratio of the heat-conducting filler 2 to the magnesium-containing particle material is (0.5-8): 100, and the mass ratio of the heat-conducting adhesive to the magnesium-containing particle material is (5-8): 100; the heat-conducting adhesive comprises silica sol-aluminum phosphate, and the mass of the silica sol-aluminum phosphate is greater than or equal to 30% of the mass of the heat-conducting adhesive; the magnesium-containing particle material comprises a first-particle-size magnesium-containing material and a second-particle-size magnesium-containing material with the particle sizes from small to large; the mass ratio of the magnesium-containing material with the first particle size to the magnesium-containing material with the second particle size is (60-70): (40-30). According to the composite material, the thermal conductivity of the composite material is greatly improved through triple effects of reducing the porosity through double-peak grading, establishing a network through the thermal conductive filler and optimizing an interface through the adhesive.

Description

Technical Field

[0001] The present application relates to the technical field of magnesium smelting, and in particular to a composite material for magnesium smelting, a preparation method thereof, and an application thereof. Background Art

[0002] In existing magnesium smelting processes, the thermal conductivity of the reduced pellets directly impacts heat transfer efficiency and reaction speed. Currently, reduced pellets are produced by pressing a mixture of solid raw materials such as calcined dolomite and ferrosilicon. These pellets have poor thermal conductivity, and conventional magnesium smelting equipment relies on external radiant heating for heat transfer. This results in a large temperature difference between the inside and outside of the pellets, impacting the reduction cycle.

[0003] The current magnesium smelting technologies based on reduced pellets include: (1) a magnesium smelting method that uses heating electrodes to enhance internal heat transfer. This method inserts a heating device similar to rapid heating into the reduction tank to enhance heat transfer within the reduction tank, thereby reducing the temperature difference between the inside and outside of the reduced pellets, thereby effectively shortening the reduction cycle, improving energy utilization efficiency and generation efficiency, and thus reducing energy consumption. (2) a method for silicon-thermal reduction of metallic magnesium at normal pressure. This method uses flowing gas to reduce the magnesium partial pressure around the magnesium raw material and the reduced pellets, so that the reduction reaction proceeds continuously and rapidly. This method overturns the traditional silicon-thermal reduction process of metallic magnesium, solves the vacuum problem of the traditional magnesium smelting process, and can realize automated continuous production of magnesium smelting. In addition, this method improves the heat transfer efficiency between the magnesium raw material and the reduced pellets by increasing the heat transfer medium and the heat transfer path, which can greatly improve production efficiency and reduce production costs. (3) Pellets for smelting metallic magnesium and their preparation methods. This preparation method uses reduction pellets formed from calcined white powder, ferrosilicon powder and fluorite powder. Based on the characteristics of the reduction pellets, such as high structural strength, good heat transfer effect and low breakage rate, the breakage rate of the reduction pellets can be effectively reduced, the magnesium yield per unit volume of magnesium raw material can be increased, and the production cost of magnesium can be reduced. The method is suitable for the industrialization of silicothermic smelting of metallic magnesium.

[0004] However, the thermal conductivity of the reduction pellets used in these existing technologies cannot meet the requirements of short-cycle magnesium smelting, so that the reduction cycle of magnesium smelting is generally more than 10 hours. Summary of the Invention

[0005] The present application provides a composite material for magnesium smelting, a preparation method thereof, and an application thereof, in order to solve the following technical problem: how to improve the thermal conductivity of magnesium smelting reduction pellet materials.

[0006] In a first aspect, an embodiment of the present application provides a composite material for magnesium smelting, wherein the raw materials of the composite material include a magnesium-containing granular material, a thermally conductive filler, and a thermally conductive adhesive, wherein the mass m2 of the thermally conductive filler and the mass m1 of the magnesium-containing granular material satisfy the relationship: m2:m1=(0.5-8):100, and the mass m3 of the thermally conductive adhesive and the mass m1 of the magnesium-containing granular material satisfy the relationship: m3:m1=(5-8):100;

[0007] The thermally conductive adhesive comprises silica sol-aluminum phosphate, and the mass of the silica sol-aluminum phosphate is greater than or equal to 30% of the mass of the thermally conductive adhesive;

[0008] The magnesium-containing granular material includes a first-size magnesium-containing material and a second-size magnesium-containing material, wherein the particle size of the first-size magnesium-containing material is smaller than the particle size of the second-size magnesium-containing material; the mass m4 of the first-size magnesium-containing material and the mass m5 of the second-size magnesium-containing material satisfy the relationship: m4:m5=(60~70):(40~30).

[0009] Optionally, the particle size of the first magnesium-containing material is 0.10 mm to 0.15 mm; and / or

[0010] The particle size of the second magnesium-containing material is 0.3 mm to 0.5 mm; and / or

[0011] The particle size of the thermal conductive filler is 0.1 mm to 0.5 mm.

[0012] Optionally, the magnesium-containing particulate material includes calcined dolomite powder and / or magnesium oxide powder.

[0013] The thermally conductive filler is selected from at least one of the following: silicon carbide, aluminum oxide, hexagonal boron nitride, graphite material and aluminum electrolysis residual anode.

[0014] Optionally, the thermally conductive adhesive further includes a thermally conductive adhesive material, and the mass of the thermally conductive adhesive material is less than or equal to 70% of the mass of the thermally conductive adhesive.

[0015] Optionally, the type of the thermally conductive adhesive material is selected from at least one of the following: thermally conductive epoxy resin, epoxy colloid and thermally conductive silicone grease.

[0016] Optionally, the composite material further includes: a reducing agent and a mineralizer, and the mass m6 of the mineralizer and the mass m1 of the magnesium-containing particulate material satisfy the relationship: m6:m1=(0.5-2):100.

[0017] Optionally, the reducing agent includes ferrosilicon material and / or aluminum powder; and / or

[0018] The types of mineralizers include fluorite.

[0019] In a second aspect, an embodiment of the present application provides a method for preparing the composite material according to the first aspect, the method comprising:

[0020] Mixing magnesium-containing granular material, thermal conductive filler, thermal conductive adhesive, reducing agent and mineralizer to obtain a mixture;

[0021] Compressing the mixture to obtain a reduced material;

[0022] The reduced material is heat-treated in an oxygen-isolated environment to decompose and volatilize the thermally conductive adhesive, thereby obtaining a composite material with a porous structure.

[0023] Optionally, the heat treatment temperature is 300° C. to 600° C., and the heat treatment time is 30 min to 60 min.

[0024] In a third aspect, an embodiment of the present application provides a reduced pellet, wherein the reduced pellet comprises the composite material described in the first aspect;

[0025] The density of the reduced pellets is 1.1 g / cm 3 ~1.8g / cm 3 The porosity of the reduced pellets is 40% to 60%.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] An embodiment of the present application provides a composite material for magnesium smelting. The composite material uses two magnesium-containing particulate materials of different particle sizes, and controls the particle size of the first-size magnesium-containing material to be smaller than that of the second-size magnesium-containing material. The particle size of the second-size magnesium-containing material can be used as a large particle skeleton, and the first-size magnesium-containing material can be used as a filler, so as to promote the formation of a bimodal gradation phenomenon between different particle sizes within the magnesium-containing particulate material. Then, the mass ratio of the first-size magnesium-containing material to the second-size magnesium-containing material is controlled to be (60-70):(40-30). Based on the above-mentioned bimodal gradation phenomenon, the distribution of the pore structure of the composite material can be regulated, the filling density of the magnesium-containing particulate material can be increased, the porosity of the magnesium-containing particulate material can be reduced, and the thermal conductivity area of the magnesium-containing particles can be increased. In addition, a thermally conductive filler is introduced, and the mass ratio of the thermally conductive filler to the magnesium-containing granular material is controlled to be (0.5-8):100. The thermally conductive filler serves as a thermally conductive skeleton, and magnesium-containing granular materials of varying particle sizes are attached to the thermally conductive skeleton. This allows for the formation of a complex thermally conductive network within the composite material, thereby reducing the composite material's interfacial thermal resistance and improving its thermal conductivity. Furthermore, a thermally conductive adhesive is introduced, and the mass ratio of the thermally conductive adhesive to the magnesium-containing granular material is controlled to be (5-8):100. This adhesive stabilizes the bonding between the magnesium-containing granular materials of varying particle sizes and the thermally conductive filler, forming a stable bonding interface and improving the mechanical strength of the composite material. Furthermore, the use of a thermally conductive adhesive primarily composed of silica sol-aluminum phosphate can improve the stacking distribution between the magnesium-containing granular material and the thermally conductive filler. During the heating process of the composite material, the silica sol-aluminum phosphate decomposes and volatilizes, forming a porous structure. This porous structure optimizes the composite material's thermal interface, thereby improving its thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 A schematic flow chart of a method for preparing a composite material provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0032] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values within the range; for example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range; in addition, whenever a numerical range is indicated in this document, it is meant to include any cited number (fractional or integer) within the indicated range.

[0033] As used herein, the terms "including," "comprising," and the like mean "including but not limited to." Relational terms such as "first" and "second" are used solely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. "And / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, "plurality" means two or more; "at least one," "at least one of the following," or similar expressions, refers to any combination of these items, including any combination of single or plural items; for example, "at least one of a, b, or c," or "at least one of a, b, and c," can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or plural. "Parts" notation, such as parts by weight and parts by mass, indicates the proportional relationship between components. In this article, the parameters described by ratio should be understood as the first term of the proportional formula, in the order in which they are described, and the proportional figures should be understood as the second term. For example, if the mass ratio of substances A, B, and C is 1:2:3, then substances A, B, and C should correspond to the proportional figures in the proportional formula in the order in which they are described, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0034] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0035] It should be noted that the reduced pellets, which are made by pressing a mixture of solid raw materials such as calcined dolomite and ferrosilicon, have a single heat transfer path and high thermal resistance due to the solid-solid contact interface. The heat transfer inside the reduced pellets mainly relies on heat conduction. However, due to the limitations of the bulk density and porosity of the solid materials, it is difficult for the heat of the reduced pellets to be quickly transferred to the core area of the reduction reaction. In addition, traditional magnesium smelting equipment relies on external radiation heating, which results in a large difference between the surface temperature and the internal temperature of the reduced pellets, making it difficult to meet the high temperature stability requirements of magnesium smelting, thereby extending the reduction cycle of magnesium smelting. Depending on the magnesium smelting equipment, the reduction cycle of a horizontal magnesium smelting tank is generally 10h to 12h, and the reduction cycle of a vertical magnesium smelting tank is generally 16h to 24h.

[0036] Therefore, it is necessary to improve the thermal conductivity of the reduced pellets.

[0037] The present application provides a composite material for magnesium smelting, wherein the raw materials of the composite material include a magnesium-containing granular material, a thermally conductive filler, and a thermally conductive adhesive. The mass m2 of the thermally conductive filler and the mass m1 of the magnesium-containing granular material satisfy the relationship: m2:m1=(0.5-8):100, and the mass m3 of the thermally conductive adhesive and the mass m1 of the magnesium-containing granular material satisfy the relationship: m3:m1=(5-8):100.

[0038] The thermally conductive adhesive comprises silica sol-aluminum phosphate, and the mass of the silica sol-aluminum phosphate is greater than or equal to 30% of the mass of the thermally conductive adhesive;

[0039] The magnesium-containing granular material includes a first-size magnesium-containing material and a second-size magnesium-containing material, wherein the particle size of the first-size magnesium-containing material is smaller than the particle size of the second-size magnesium-containing material; the mass m4 of the first-size magnesium-containing material and the mass m5 of the second-size magnesium-containing material satisfy the relationship: m4:m5=(60~70):(40~30).

[0040] It should be noted that the embodiments of the present application provide a composite material for magnesium smelting, which synergistically improves thermal conductivity through three key mechanisms: multi-scale particle grading, thermal network construction, and interface optimization. The specific principles are as follows:

[0041] 1. Bimodal gradation to control pore structure:

[0042] (1) Role of large particle skeleton: The second-size magnesium-containing material (larger particles) serves as a structural skeleton, providing mechanical support and forming macroscopic pore channels.

[0043] (2) Small particle filling effect: The first-size magnesium-containing material (smaller particles) fills the pores between large particles, forming a tightly packed structure and significantly reducing the overall porosity.

[0044] (3) Improved thermal conductivity: The number of contact points between particles increases, the effective thermal conductivity path (i.e., solid-solid contact area) increases, and the obstruction of pores to heat conduction is reduced.

[0045] 2. Thermally conductive fillers build a three-dimensional thermal network:

[0046] (1) Formation of thermal conductive skeleton: The thermal conductive filler is dispersed in the magnesium-containing particle material at a ratio of (0.5-8):100 to form a continuous or semi-continuous thermal conductive path.

[0047] (2) Reduced interfacial thermal resistance: The high thermal conductivity of the thermally conductive filler preferentially conducts heat and reduces phonon scattering through close contact with the magnesium-containing particles.

[0048] (3) Multi-scale synergistic effect: Large particle fillers provide long-range heat conduction paths, and small particle fillers fill local thermal resistance gaps to form a hierarchical heat conduction network.

[0049] 3. Thermally conductive adhesive optimizes interface bonding:

[0050] (1) Chemical bonding to stabilize the interface: The silica sol-aluminum phosphate binder enhances the interfacial bonding strength between magnesium-containing particles and thermally conductive fillers through Si-O-Mg and Al-O-Mg bonding, thereby reducing interface defects.

[0051] (2) Stacking state regulation: The thermal conductive adhesive promotes the rearrangement of particles during the curing process, optimizes the contact angle between the thermal conductive filler and the magnesium particles, and makes the heat flow direction more compatible with the thermal conductive network.

[0052] (3) Mechanical-thermal synergy: The amount of thermal conductive adhesive (5-8):100 balances the interfacial bonding force and the effective dispersion of thermal conductive fillers, avoiding excessive adhesive blocking the thermal path.

[0053] (4) Regulation during the reduction stage: The silica sol-aluminum phosphate binder will decompose and volatilize during the use of the composite material, forming a loose porous structure in the composite material. This porous structure will not only regulate the porosity of the composite material, but also directionally improve the uniformity of the pore distribution of the thermal conductive network.

[0054] Therefore, an embodiment of the present application provides a composite material for magnesium smelting. The composite material significantly improves the thermal conductivity of the composite material through the triple effects of bimodal grading to reduce porosity, thermally conductive filler to build a network, and adhesive to optimize the interface, while maintaining the high mechanical strength of the composite material, making it suitable for high-temperature magnesium smelting environments.

[0055] The mass m2 of the thermally conductive filler may be 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5 or 8.0.

[0056] The mass m3 of the thermally conductive adhesive may be 5, 6, 7 or 8.

[0057] The mass m4 of the magnesium-containing material of the first particle size can be 60, 61, 62, 63, 64, 65, 66, 67, 68, 69 or 70.

[0058] The mass m5 of the magnesium-containing material of the second particle size can be 40, 39, 38, 37, 36, 35, 34, 33, 32, 31 or 30.

[0059] In some optional embodiments, the particle size of the first-size magnesium-containing material is 0.10 mm to 0.15 mm; and / or

[0060] The particle size of the second magnesium-containing material is 0.3 mm to 0.5 mm; and / or

[0061] The particle size of the thermal conductive filler is 0.1 mm to 0.5 mm.

[0062] In these embodiments, the second magnesium-containing material with a particle size of 0.3 mm to 0.5 mm can serve as a large particle skeleton to effectively support the small first particle size magnesium-containing material, while the first magnesium-containing material with a particle size of 0.10 mm to 0.15 mm can serve as a small particle filler, promoting the formation of a bimodal gradation phenomenon between different particle sizes within the magnesium-containing particulate material. This can regulate the distribution of the pore structure of the composite material, increase the packing density of the magnesium-containing particulate material, thereby reducing the porosity of the magnesium-containing particulate material and increasing the thermal conductivity area of the magnesium-containing particles. In addition, the 0.1 mm to 0.5 mm thermally conductive filler can be effectively dispersed in the magnesium-containing particulate material to form a complex thermal conductive network and reduce phonon scattering, thereby effectively reducing the interfacial thermal resistance of the magnesium-containing particulate material, ultimately improving the thermal conductivity of the composite material.

[0063] The particle size of the first particle size magnesium-containing material may be 0.10 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm or 0.15 mm.

[0064] The particle size of the second size magnesium-containing material may be 0.3 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, 0.35 mm, 0.40 mm, 0.45 mm or 0.50 mm.

[0065] The particle size of the thermally conductive filler may be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm or 0.5 mm.

[0066] In some optional embodiments, the magnesium-containing particulate material includes calcined dolomite powder and / or magnesium oxide powder.

[0067] The thermally conductive filler is selected from at least one of the following: silicon carbide, aluminum oxide, hexagonal boron nitride, graphite material and aluminum electrolysis residual anode.

[0068] In these embodiments, the use of calcined dolomite powder or magnesium oxide powder as the magnesium-containing particulate material can ensure that the magnesium-containing particulate material has sufficient magnesium, thereby providing a magnesium-containing particulate material with sufficient reducibility for magnesium smelting. In addition, silicon carbide, aluminum oxide, hexagonal boron nitride, graphite material, or residual aluminum electrolytic anodes can be used as thermally conductive fillers. These thermally conductive fillers have good thermal conductivity coefficients and can form a complex thermal conductive network between the two magnesium-containing particulate materials of different particle sizes, thereby improving the thermal conductivity of the composite material.

[0069] It should be noted that the calcined dolomite powder refers to a mixture of magnesium oxide and calcium oxide obtained by calcining dolomite at a high temperature of 1100° C. to 1200° C., and the hydration activity of the calcined dolomite powder is greater than or equal to 28%.

[0070] It should be noted that the residual anode of aluminum electrolysis refers to the waste generated by electrolysis and physical wear of the anode carbon block after long-term use during the aluminum electrolysis process. Its components include: petroleum coke, cryolite, aluminum oxide and iron oxide. These components meet the following requirements: the mass content of petroleum coke is approximately 75%, the mass content of cryolite is approximately 11%, the mass content of aluminum oxide is approximately 6%, the mass content of iron oxide is approximately 4%, and the mass content of other impurities is approximately 4%.

[0071] In some optional embodiments, the thermally conductive adhesive further includes a thermally conductive adhesive material, and the mass of the thermally conductive adhesive material is less than or equal to 70% of the mass of the thermally conductive adhesive.

[0072] In these embodiments, the thermally conductive adhesive material, which is less than or equal to 70% of the mass of the thermally conductive adhesive, can improve the bonding performance of the thermally conductive adhesive, thereby improving the interfacial bonding strength between the magnesium-containing particles and the thermally conductive filler, and improving the interfacial bonding force and stability of the composite material. At the same time, the thermally conductive adhesive material can improve the heat flow direction of the thermal conductive network formed by the magnesium-containing particle material and the thermally conductive filler, thereby improving the thermal conductivity of the composite material.

[0073] The mass of the thermally conductive adhesive material may be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50% of the mass of the thermally conductive adhesive.

[0074] In some optional embodiments, the type of the thermally conductive adhesive material is selected from at least one of the following: thermally conductive epoxy resin, epoxy colloid, and thermally conductive silicone grease.

[0075] In these embodiments, thermally conductive epoxy resin, epoxy colloid or thermally conductive silicone grease is used as the thermally conductive adhesive material. These thermally conductive adhesive materials can improve the bonding force between the magnesium-containing particles and the thermally conductive filler, and can also improve the thermal conductivity of the composite material based on the thermal conductivity of the thermally conductive adhesive material.

[0076] In some optional embodiments, the composite material further includes: a reducing agent and a mineralizer, and the mass m6 of the mineralizer and the mass m1 of the magnesium-containing particulate material satisfy the relationship: m6:m1=(0.5-2):100.

[0077] In these embodiments, a reducing agent is introduced into the composite material, and the mass ratio of the reducing agent to the magnesium-containing particulate material is controlled to meet the reducibility requirements of magnesium smelting; in addition, a mineralizer is introduced into the composite material, and the mass ratio of the mineralizer to the magnesium-containing particulate material is controlled to (0.5-2):100. The mineralizer can increase the reduction reaction efficiency of the composite material to facilitate the formation of a regular composite material.

[0078] It should be noted that the chemical equation of the reduction reaction initiated by the reducing agent can be:

[0079] (1) 2CaO·MgO +Si = 2Mg + Ca2SiO4; (2) 4MgO +2A1 = 3Mg +MgAl2O4.

[0080] It should be noted that the mass ratio of the reducing agent and the magnesium-containing particulate material is balanced according to the above two reaction chemical equations.

[0081] The mass m6 of the mineralizer can be 0.5, 1.0, 1.5 or 2.0.

[0082] In some optional embodiments, the reducing agent includes ferrosilicon material and / or aluminum powder; and / or

[0083] The types of mineralizers include fluorite.

[0084] In these embodiments, the use of a reducing agent of ferrosilicon material can effectively improve the reduction performance of the composite material, so that the composite material can meet the reduction performance requirements of magnesium smelting; in addition, the use of a mineralizer of fluorite can improve the mineralization degree of the composite material, thereby ultimately forming a composite material with a regular shape.

[0085] Figure 1 A schematic flow chart of a method for preparing a composite material provided in an embodiment of the present application is shown as an example;

[0086] Based on a general inventive concept, such as Figure 1 As shown, an embodiment of the present application provides a method for preparing the composite material, the method comprising:

[0087] S1. The magnesium-containing particulate material, a thermally conductive filler, a thermally conductive adhesive, a reducing agent and a mineralizer are mixed to obtain a mixture;

[0088] S2. The mixture is pressed to obtain a reducing material;

[0089] S3. heat-treating the reduced material in an oxygen-isolated environment to decompose and volatilize the thermally conductive adhesive to obtain a composite material having a porous structure.

[0090] This method is a method for preparing the above-mentioned composite material. The specific composition of the composite material can refer to the above-mentioned embodiment. Since this method adopts part or all of the technical solutions of the above-mentioned embodiment, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be described one by one here.

[0091] It should be noted that the heat treatment can be performed in a vacuum environment or an inert gas atmosphere.

[0092] It should be noted that the composite material can be directly used in the reduction reaction process of magnesium smelting.

[0093] In some optional embodiments, the heat treatment temperature is 300° C. to 600° C., and the heat treatment time is 30 min to 60 min.

[0094] In these embodiments, the heat treatment at 300°C to 600°C and for 30 minutes to 60 minutes can preheat the reducing material while its thermally conductive adhesive can be fully decomposed and volatilized to form a loose porous structure. This porous structure not only regulates the porosity of the composite material, but also directionally improves the uniformity of the pore distribution of the thermal conductive network.

[0095] The temperature of the heat treatment may be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, or 600°C.

[0096] The heat treatment time can be 30 min, 40 min, 45 min, 50 min, 55 min or 60 min.

[0097] Based on a general inventive concept, an embodiment of the present application provides a reduced pellet, wherein the reduced pellet comprises the composite material;

[0098] The density of the reduced pellets is 1.1 g / cm 3 ~1.8g / cm 3 The porosity of the reduced pellets is 40% to 60%.

[0099] The reduction pellet is realized based on the above-mentioned composite material. The specific structure of the composite material can refer to the above-mentioned embodiment. Since the reduction pellet adopts part or all of the technical solutions of the above-mentioned embodiment, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be described one by one here.

[0100] It should be noted that 1.1g / cm 3 ~1.8g / cm 3 The reduced pellets have a density of 1.5 and a porosity of 40% to 60%, indicating that the reduced pellets with ideal porosity and density can be obtained by using the composite material.

[0101] The density of the reduced pellets can be 1.1 g / cm 3 , 1.2g / cm 3 , 1.3g / cm 3 , 1.4g / cm 3 , 1.5g / cm 3 , 1.6g / cm 3 , 1.7g / cm 3 or 1.8g / cm 3 .

[0102] The porosity of the reduced pellets may be 40%, 41%, 42%, 43%, 44%, 45%, 50%, 55% or 60%.

[0103] The present application is further described below with reference to specific examples. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national / industry standards. If there are no corresponding national / industry standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.

[0104] Example 1

[0105] A composite material for magnesium smelting, wherein the raw materials of the composite material include magnesium-containing granular material, thermally conductive filler and thermally conductive adhesive, wherein the mass m2 of the thermally conductive filler and the mass m1 of the magnesium-containing granular material satisfy the relationship: m2:m1=5:100, and the mass m3 of the thermally conductive adhesive and the mass m1 of the magnesium-containing granular material satisfy the relationship: m3:m1=8:100;

[0106] The thermal conductive adhesive includes silica sol-aluminum phosphate, and the mass of the silica sol-aluminum phosphate is 5% of the mass of the magnesium-containing particle material;

[0107] The magnesium-containing particulate material includes a first-size magnesium-containing material and a second-size magnesium-containing material. The mass m4 of the first-size magnesium-containing material and the mass m5 of the second-size magnesium-containing material satisfy the relationship: m4:m5=60:40-30.

[0108] The first particle size of the magnesium-containing material is 0.10 mm to 0.15 mm;

[0109] The second particle size of the magnesium-containing material is 0.3mm to 0.5mm

[0110] The type of magnesium-containing particulate material is calcined dolomite powder.

[0111] The type of thermal conductive filler is selected from silicon carbide and hexagonal boron nitride, the mass fraction of silicon carbide is 2%, and the mass fraction of hexagonal boron nitride is 3%.

[0112] The thermally conductive adhesive further comprises a thermally conductive adhesive material, the mass of which is 3% of the mass of the magnesium-containing particle material.

[0113] The type of thermally conductive adhesive material is thermal grease.

[0114] The composite material also includes: a reducing agent and a mineralizer. The mass m6 of the mineralizer and the mass m1 of the magnesium-containing particulate material satisfy the relationship: m6:m1=2:100.

[0115] The type of reducing agent is ferrosilicon;

[0116] The type of mineralizer is fluorite.

[0117] like Figure 1 As shown, the embodiment of the present application provides a method for preparing the composite material of the first aspect, the method comprising:

[0118] S1. The magnesium-containing particulate material, a thermally conductive filler, a thermally conductive adhesive, a reducing agent and a mineralizer are mixed to obtain a mixture;

[0119] S2. The mixture is pressed to obtain a reducing material;

[0120] S3. Heat-treating the reduced material in an oxygen-isolated environment to decompose and volatilize the thermally conductive adhesive, thereby obtaining a composite material having a porous structure.

[0121] The heat treatment temperature is 500°C and the heat treatment time is 60 minutes.

[0122] Example 2

[0123] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0124] The mass m2 of the thermal conductive filler and the mass m1 of the magnesium-containing granular material satisfy the relationship: m2:m1=6:100, and the mass m3 of the thermal conductive adhesive and the mass m1 of the magnesium-containing granular material satisfy the relationship: m3:m1=5:100;

[0125] The mass of silica sol-aluminum phosphate is 2% of the mass of the magnesium-containing particulate material;

[0126] The mass m4 of the magnesium-containing material of the first particle size and the mass m5 of the magnesium-containing material of the second particle size satisfy the relationship: m4:m5=65:35.

[0127] The types of thermal conductive filler are selected from: aluminum oxide and aluminum electrolysis residual anode, the mass fraction of aluminum oxide is 1%, and the mass fraction of aluminum electrolysis residual anode is 5%.

[0128] The mass of the thermally conductive adhesive material is 3% of the mass of the magnesium-containing particle material.

[0129] The type of thermal conductive adhesive material is high thermal conductive epoxy resin.

[0130] The mass m6 of the mineralizer and the mass m1 of the magnesium-containing particulate material satisfy the relationship: m6:m1=1.0:100.

[0131] Example 3

[0132] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0133] The mass m2 of the thermal conductive filler and the mass m1 of the magnesium-containing granular material satisfy the relationship: m2:m1=3.5:100, and the mass m3 of the thermal conductive adhesive and the mass m1 of the magnesium-containing granular material satisfy the relationship: m3:m1=3:100;

[0134] The mass of silica sol-aluminum phosphate is 2% of the mass of the magnesium-containing particulate material;

[0135] The mass m4 of the magnesium-containing material of the first particle size and the mass m5 of the magnesium-containing material of the second particle size satisfy the relationship: m4:m5=70:30.

[0136] The types of thermal conductive filler are selected from: graphite and aluminum electrolysis residual anode, the mass fraction of graphite is 0.5%, and the mass fraction of aluminum electrolysis residual anode is 5%.

[0137] The mass of the thermally conductive adhesive material is 1% of the mass of the magnesium-containing particle material.

[0138] The type of thermal conductive adhesive material is high temperature resistant epoxy colloid.

[0139] The mass m6 of the mineralizer and the mass m1 of the magnesium-containing particulate material satisfy the relationship: m6:m1=0.5:100.

[0140] Example 4

[0141] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0142] The type of magnesium-containing particulate material is magnesium oxide powder.

[0143] The mass m2 of the thermal conductive filler and the mass m1 of the magnesium-containing granular material satisfy the relationship: m2:m1=7:100, and the mass m3 of the thermal conductive adhesive and the mass m1 of the magnesium-containing granular material satisfy the relationship: m3:m1=6:100;

[0144] The mass of silica sol-aluminum phosphate is 4% of the mass of the magnesium-containing particulate material;

[0145] The mass m4 of the magnesium-containing material of the first particle size and the mass m5 of the magnesium-containing material of the second particle size satisfy the relationship: m4:m5=70:30.

[0146] The type of thermal conductive filler is selected from: aluminum oxide and hexagonal boron nitride, the mass fraction of aluminum oxide is 4%, and the mass fraction of hexagonal boron nitride is 3%.

[0147] The mass of the thermally conductive adhesive material is 2% of the mass of the magnesium-containing particle material.

[0148] The type of thermally conductive adhesive material is thermal grease.

[0149] The mass m6 of the mineralizer and the mass m1 of the magnesium-containing particulate material satisfy the relationship: m6:m1=1.5:100.

[0150] The type of reducing agent is aluminum powder.

[0151] Example 5

[0152] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0153] The type of magnesium-containing particulate material is magnesium oxide powder.

[0154] The mass m2 of the thermal conductive filler and the mass m1 of the magnesium-containing granular material satisfy the relationship: m2:m1=1:100, and the mass m3 of the thermal conductive adhesive and the mass m1 of the magnesium-containing granular material satisfy the relationship: m3:m1=3:100;

[0155] The mass of the silica sol-aluminum phosphate is 1% of the mass of the magnesium-containing particulate material.

[0156] The type of thermal conductive filler is selected from: graphite and hexagonal boron nitride, the mass fraction of graphite is 0.5%, and the mass fraction of hexagonal boron nitride is 0.5%.

[0157] The mass of the thermally conductive adhesive material is 2% of the mass of the magnesium-containing particle material.

[0158] The type of thermally conductive adhesive material is thermal grease.

[0159] The mass m6 of the mineralizer and the mass m1 of the magnesium-containing particulate material satisfy the relationship: m6:m1=0.5:100.

[0160] The type of reducing agent is aluminum powder.

[0161] Comparative Example 1

[0162] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0163] Instead of using magnesium-containing granular materials of two particle sizes, the magnesium-containing material of the first particle size is directly used;

[0164] At the same time, no thermal conductive filler or thermal conductive adhesive is added.

[0165] Comparative Example 2

[0166] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0167] Instead of using two sizes of magnesium-containing granular materials, directly use the first size magnesium-containing material

[0168] Comparative Example 3

[0169] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0170] Instead of using magnesium-containing particulate materials of two particle sizes, the magnesium-containing material of the second particle size is directly used.

[0171] Comparative Example 4

[0172] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0173] No thermally conductive filler is used.

[0174] Comparative Example 5

[0175] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0176] No thermally conductive adhesive is used.

[0177] Related experiments and effect data:

[0178] The composite materials of each embodiment and comparative example were prepared according to a preset pellet shape, and their performance was tested. The results are shown in Table 1. At the same time, they were tested in the reduction stage of magnesium smelting, and the final reduction rate and reduction cycle data of magnesium smelting were calculated. The reduction cycle was then compared with that of Comparative Example 1. The reduction cycle shortening rate compared to Comparative Example 1 at a certain reduction rate was calculated as follows: reduction cycle shortening rate = (reduction cycle of Comparative Example 1 - reduction cycle of each embodiment and comparative example) / reduction cycle of Comparative Example 1. The results are shown in Table 2.

[0179] Table 1 Characterization of the composite materials of each embodiment and comparative example

[0180]

[0181]

[0182] Table 2 Reduction period and reduction rate of the composite materials of each embodiment and comparative example

[0183]

[0184] As can be seen from Tables 1 and 2, the embodiment of the present application provides a composite material for magnesium smelting. The composite material can shorten the reduction cycle of the composite material used in magnesium smelting by 25% to 40% through the multiple effects of bimodal grading to reduce porosity, thermally conductive filler to build a network, and binder to optimize the interface. In addition, the composite material can maintain a relatively complete morphology and good porosity, so that the composite material has high mechanical strength and can reduce the canning breakage rate to below 2.0%.

[0185] Compared with Example 1, Comparative Example 1 does not use magnesium-containing particulate materials of different particle sizes, thermally conductive fillers and thermally conductive adhesives, resulting in a higher density of the composite material, and a lower canning breakage rate and porosity of the composite material, which indicates that the mechanical strength of the composite material is poor; and during the magnesium smelting process, the reduction cycle of the composite material is longer, which indicates that its thermal conductivity is poor.

[0186] Compared with Example 1, Comparative Examples 2 and 3 respectively use magnesium-containing granular materials of a single particle size. Although the density, canning breakage rate and porosity of the two composite materials are close to those of the embodiment, the reduction cycle of the two composite materials is longer during the actual magnesium smelting process, which indicates that their thermal conductivity is poor.

[0187] Compared with Example 1, Comparative Example 4 does not use thermally conductive fillers. Although the density, canning breakage rate and porosity of the composite material of Comparative Example 4 are close to those of the embodiment, the reduction cycle of the composite material is longer in the actual magnesium smelting process, which indicates that its thermal conductivity is poor.

[0188] Compared with Example 1, Comparative Example 5 does not use a thermally conductive adhesive. The porosity of the composite material of Comparative Example 5 is smaller and the canning breakage rate is larger, which indicates that not using a thermally conductive adhesive has a certain impact on the mechanical strength of the composite material. In addition, the reduction cycle of the composite material is longer during the actual magnesium smelting process, which also indicates that its thermal conductivity is poor.

[0189] In summary, the embodiments of the present application provide a composite material for magnesium smelting, which significantly improves the thermal conductivity of the composite material through the triple effects of reducing porosity by bimodal grading, building a network with thermally conductive fillers, and optimizing the interface with adhesives.

[0190] In addition, the composite material for magnesium smelting provided in the embodiment of the present application, based on its high thermal conductivity, enables the composite material to effectively reduce the energy consumption of magnesium smelting when used in the magnesium smelting stage and improve the production efficiency of magnesium smelting in the reduction stage.

[0191] The foregoing is merely a detailed description of the present invention, intended to enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but rather is intended to conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A composite material for magnesium smelting, wherein the raw materials of the composite material include a magnesium-containing particulate material, a thermally conductive filler, and a thermally conductive adhesive, wherein the mass m2 of the thermally conductive filler and the mass m1 of the magnesium-containing particulate material satisfy the relationship: m2:m1=(0.5-8):100, and the mass m3 of the thermally conductive adhesive and the mass m1 of the magnesium-containing particulate material satisfy the relationship: m3:m1=(5-8):100; The thermally conductive adhesive comprises silica sol-aluminum phosphate, and the mass of the silica sol-aluminum phosphate is greater than or equal to 30% of the mass of the thermally conductive adhesive; The magnesium-containing granular material includes a first-size magnesium-containing material and a second-size magnesium-containing material, wherein the particle size of the first-size magnesium-containing material is smaller than the particle size of the second-size magnesium-containing material; the mass m4 of the first-size magnesium-containing material and the mass m5 of the second-size magnesium-containing material satisfy the relationship: m4:m5=(60~70):(40~30).

2. The composite material according to claim 1, characterized in that The particle size of the first-size magnesium-containing material is 0.10 mm to 0.15 mm; and / or The particle size of the second magnesium-containing material is 0.3 mm to 0.5 mm; and / or The particle size of the thermal conductive filler is 0.1 mm to 0.5 mm.

3. The composite material according to claim 1, characterized in that The types of magnesium-containing particulate materials include calcined dolomite powder and / or magnesium oxide powder; The thermally conductive filler is selected from at least one of the following: silicon carbide, aluminum oxide, hexagonal boron nitride, graphite material and aluminum electrolysis residual anode.

4. The composite material according to claim 1, characterized in that The thermally conductive adhesive further includes a thermally conductive adhesive material, and the mass of the thermally conductive adhesive material is less than or equal to 70% of the mass of the thermally conductive adhesive.

5. The composite material according to claim 4, characterized in that The thermally conductive adhesive material is selected from at least one of the following: thermally conductive epoxy resin, epoxy colloid and thermally conductive silicone grease.

6. The composite material according to claim 1, characterized in that The composite material further includes: a reducing agent and a mineralizer, and the mass m6 of the mineralizer and the mass m1 of the magnesium-containing particulate material satisfy the relationship: m6:m1=(0.5-2):

100.

7. The composite material according to claim 6, characterized in that The types of reducing agents include ferrosilicon materials and / or aluminum powder; and / or The types of mineralizers include fluorite.

8. A method for preparing the composite material according to any one of claims 1 to 7, the method comprising: Mixing magnesium-containing granular material, thermal conductive filler, thermal conductive adhesive, reducing agent and mineralizer to obtain a mixture; Compressing the mixture to obtain a reduced material; The reduced material is heat-treated in an oxygen-isolated environment to decompose and volatilize the thermally conductive adhesive, thereby obtaining a composite material with a porous structure.

9. The method according to claim 8, characterized in that The temperature of the heat treatment is 300° C. to 600° C., and the time of the heat treatment is 30 min to 60 min.

10. A reduced pellet comprising the composite material according to any one of claims 1 to 7; The density of the reduced pellets is 1.1 g / cm 3 ~1.8g / cm 3 The porosity of the reduced pellets is 40% to 60%.

Images