Lightweight periclase-magnesia-alumina spinel-carbon refractory and method for producing the same

Abstract

The present application relates to a kind of lightweight periclase-magnesium aluminate spinel-carbon refractory and its preparation method.The technical scheme is:20-25wt% of the porous periclase-magnesium aluminate spinel refractory aggregate I,18-23wt% of the porous periclase-magnesium aluminate spinel refractory aggregate II and 15-22wt% of the porous periclase-magnesium aluminate spinel refractory aggregate III are total aggregate,31-45wt% of magnesia fine powder,0.1-1.5wt% of elemental silicon powder and 0.5-3.5wt% of flake graphite powder are total matrix.The total aggregate is placed in the mixer first,add 2-6wt% of modified liquid thermosetting phenolic resin which is the sum of total aggregate and total matrix,uniformly mix,then add total matrix,agitate,press into shape,keep at 180-300 DEG C,obtain lightweight periclase-magnesium aluminate spinel-carbon refractory.The product has the characteristics of multi-scale core-shell structure,low thermal conductivity,excellent thermal shock resistance,excellent erosion resistance and good oxidation resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of periclase-magnesia alumina spinel-carbon refractory materials. In particular, it relates to a lightweight periclase-magnesia alumina spinel-carbon refractory material and a preparation method thereof. BACKGROUND

[0002] Periclase-magnesia alumina spinel-carbon refractory materials are widely used in the low-carbon steel smelting industry for molten steel storage and diversion due to their excellent thermodynamic properties and erosion resistance, such as tundish and nozzle.

[0003] Currently, there are many methods for preparing periclase-magnesia alumina spinel-carbon refractory materials:

[0004] For example, the literature technology (Yang Dinghao et al., Influence of molding pressure direction on properties of periclase-spinel-carbon brick. Journal of Luoyang Institute of Technology, 2002, 23(4): 88-90) uses medium-grade magnesia, spinel synthetic sand, graphite, and pitch as raw materials to prepare a periclase-magnesia alumina spinel-carbon brick. However, this technology uses dense magnesia and spinel synthetic sand as aggregate, which has poor interface bonding between aggregate and matrix, resulting in poor erosion resistance of the refractory material. In addition, the dense aggregate has a high thermal conductivity, which increases the thermal conductivity of the refractory material and leads to high heat loss.

[0005] For example, the patent technology "A lightweight periclase-spinel-carbon refractory material and a preparation method thereof" (CN202110025196.X) uses modified porous periclase-spinel ceramic particles, modified porous periclase-spinel ceramic fine powder, elemental Si powder, carbon powder, and liquid thermosetting phenolic resin as raw materials to prepare a lightweight periclase-magnesia alumina spinel-carbon refractory material. However, this technology uses magnesite as raw material to prepare porous periclase-magnesia alumina spinel ceramic particles, which has many impurities, resulting in more liquid phase and larger pore size at high temperatures, which reduces the oxidation resistance of the refractory material.

[0006] For example, the literature technology (Peng Conghua et al., Slag resistance of microporous magnesia-spinel-carbon refractory material. Bulletin of the Chinese Ceramic Society, 2009, 28(2): 307-311) uses periclase-spinel microporous ceramic, fused magnesia, flake graphite, metallic aluminum powder, and phenolic resin as raw materials to prepare a lightweight periclase-magnesia alumina spinel-carbon refractory material. Although the thermal conductivity of this refractory material is reduced, the refractory material has more liquid phase at high temperatures, and the pores grow and coalesce, and the spinel is randomly distributed, which reduces the erosion resistance and thermal shock stability of the refractory material. SUMMARY

[0007] The present application aims to overcome the shortcomings of existing technologies and provide a lightweight periclase-magnesia alumina spinel-carbon refractory material with low thermal conductivity, excellent thermal shock stability, excellent erosion resistance, and good oxidation resistance, as well as a preparation method thereof.

[0008] To achieve the above object, the technical solution of the present application adopts the following steps:

[0009] Step 1, preparation of the multi-microporous periclase-magnesium aluminate spinel ceramic with micro-nucleus shell structure

[0010] Step 1.1, using any one of alumina nano-powder, alumina micro-powder and aluminum hydroxide micro-powder as the aluminum source, or using any two of the mixed powders of alumina nano-powder, alumina micro-powder and aluminum hydroxide micro-powder as the aluminum source, or using the mixed powders of the three of alumina nano-powder, alumina micro-powder and aluminum hydroxide micro-powder as the aluminum source.

[0011] Step 1.2, placing 79-97wt% of magnesium hydroxide fine powder and 3-21wt% of the aluminum source in a blender, adding 4.5-5.5wt% of water to the sum of the magnesium hydroxide fine powder and the aluminum source, and stirring for 1-3h to obtain a mixture.

[0012] Step 1.3, machine pressing the mixture under the condition of 100-200MPa to form a green body, drying the formed green body at 110-220℃ for 24-48h, then placing the dried green body in a high-temperature furnace, heating at a rate of 1-3℃ / min to 300-400℃, maintaining the temperature for 0.5-3h, then heating at a rate of 3-5℃ / min to 1600-1800℃, maintaining the temperature for 3-8h, and cooling with the furnace to obtain the multi-microporous periclase-magnesium aluminate spinel ceramic with micro-nucleus shell structure.

[0013] The multi-microporous periclase-magnesium aluminate spinel ceramic with micro-nucleus shell structure is crushed and sieved to obtain multi-microporous periclase-magnesium aluminate spinel refractory aggregate I with a particle size of less than 5mm and greater than or equal to 3mm, multi-microporous periclase-magnesium aluminate spinel refractory aggregate II with a particle size of less than 3mm and greater than or equal to 1mm, and multi-microporous periclase-magnesium aluminate spinel refractory aggregate III with a particle size of less than 1mm and greater than or equal to 0.1mm. The multi-microporous periclase-magnesium aluminate spinel refractory aggregate I, the multi-microporous periclase-magnesium aluminate spinel refractory aggregate II and the multi-microporous periclase-magnesium aluminate spinel refractory aggregate III are collectively referred to as multi-microporous periclase-magnesium aluminate spinel refractory aggregate.

[0014] The multi-microporous periclase-magnesium aluminate spinel refractory aggregate has a micro-nucleus shell structure with a multi-microporous magnesium oxide micro-particle containing nano-pores as the nucleus and a continuous dense magnesium aluminate spinel layer as the shell. The particle size of the multi-microporous magnesium oxide micro-particle is 20-45μm, and the thickness of the continuous dense magnesium aluminate spinel layer is 2-5μm. The total content of Al2O3 and MgO in the multi-microporous periclase-magnesium aluminate spinel refractory aggregate is >99.55%, the apparent porosity is 15-30%, and the bulk density is 2.45-3.04g / cm 3The light-weighted periclase-magnesia-alumina spinel-carbon refractory material has a mean pore size of 254-809 nm, a compressive strength of 60-130 MPa, and a thermal conductivity of 4.04-6.54 W / (m·K) at 800 DEG C.

[0015] Step 2, preparation of light-weighted periclase-magnesia-alumina spinel-carbon refractory material

[0016] The light-weighted periclase-magnesia-alumina spinel-carbon refractory material has a mean pore size of 254-809 nm, a compressive strength of 60-130 MPa, and a thermal conductivity of 4.04-6.54 W / (m·K) at 800 DEG C.

[0017] The light-weighted periclase-magnesia-alumina spinel-carbon refractory material has a mean pore size of 254-809 nm, a compressive strength of 60-130 MPa, and a thermal conductivity of 4.04-6.54 W / (m·K) at 800 DEG C.

[0018] The light-weighted periclase-magnesia-alumina spinel-carbon refractory material has a mean pore size of 254-809 nm, a compressive strength of 60-130 MPa, and a thermal conductivity of 4.04-6.54 W / (m·K) at 800 DEG C.

[0019] The light-weighted periclase-magnesia-alumina spinel-carbon refractory material has a mean pore size of 254-809 nm, a compressive strength of 60-130 MPa, and a thermal conductivity of 4.04-6.54 W / (m·K) at 800 DEG C.

[0020] The light-weighted periclase-magnesia-alumina spinel-carbon refractory material has a mean pore size of 254-809 nm, a compressive strength of 60-130 MPa, and a thermal conductivity of 4.04-6.54 W / (m·K) at 800 DEG C.

[0021] The light-weighted periclase-magnesia-alumina spinel-carbon refractory material has a mean pore size of 254-809 nm, a compressive strength of 60-130 MPa, and a thermal conductivity of 4.04-6.54 W / (m·K) at 800 DEG C.

[0022] The light-weighted periclase-magnesia-alumina spinel-carbon refractory material has a mean pore size of 254-809 nm, a compressive strength of 60-130 MPa, and a thermal conductivity of 4.04-6.54 W / (m·K) at 800 DEG C.

[0023] The light-weighted periclase-magnesia-alumina spinel-carbon refractory material has a mean pore size of 254-809 nm, a compressive strength of 60-130 MPa, and a thermal conductivity of 4.04-6.54 W / (m·K) at 800 DEG C.

[0024] The particle size of the magnesium hydroxide fine powder is < 100 mu m; and the MgO content of the magnesium hydroxide fine powder is 64-66 wt%.

[0025] The particle size of the magnesia fine powder is < 88 mu m; and the MgO content of the magnesia fine powder is 95-97 wt%.

[0026] The particle size of the elemental silicon powder is < 50 mu m; and the Si content of the elemental silicon powder is 98-99.5 wt%.

[0027] The particle size of the flake graphite powder is < 18 mu m; and the C content of the flake graphite powder is 97-98.5 wt%.

[0028] The carbon residue rate of the liquid thermosetting phenolic resin is >= 35%.

[0029] Compared with the prior art, the application has the following positive effects:

[0030] The application designs the whole process from raw materials, refractory aggregate to refractory materials. In the aggregate aspect, the multi-microporous magnesia micro-particle with nano-pores is formed by in-situ decomposition of magnesium hydroxide as the core, a continuous and dense magnesium aluminate spinel layer is formed by introducing special particle size of aluminum source, in-situ reaction and process as the shell, and the multi-microporous periclase-magnesium aluminate spinel refractory aggregate with micro-core-shell structure and accurately controlled magnesium aluminate spinel distribution is obtained. The particle size of the multi-microporous magnesia micro-particle is 20-45 mu m, and the thickness of the continuous and dense magnesium aluminate spinel layer is 2-5 mu m. Compared with the prior art, the prepared aggregate has high purity, stable high-temperature structure, low thermal conductivity and excellent high-temperature service performance. In the light-weight periclase-magnesium aluminate spinel-carbon refractory material, the special particle size of aluminum source is wrapped on the surface of the aggregate with micro-core-shell structure to form a continuous alumina layer with a thickness of 0.1-0.3 mm, and then the continuous and dense magnesium aluminate spinel layer is formed by in-situ decomposition synthesis method under the conditions of carbon-embedded atmosphere and 1200-1400 DEG C heat preservation. On the one hand, a flake graphite-magnesium aluminate spinel inlaid structure is formed at the shell-matrix interface, and on the other hand, a serrated occlusion interface structure is formed at the shell-aggregate interface, which together with the multi-microporous periclase-magnesium aluminate spinel refractory aggregate with micro-core-shell structure forms a multi-scale core-shell structure, and fully plays the advantages of nano-scale pores, magnesia, magnesium aluminate spinel and flake graphite. The problems of high thermal conductivity, poor thermal shock stability and poor erosion resistance of the existing dense periclase-magnesium aluminate spinel-carbon refractory material are overcome, and the problem of large pore size and poor oxidation resistance of the existing light-weight periclase-magnesium aluminate spinel-carbon refractory material due to many impurities in the aggregate is solved.

[0031] The application adopts the multi-porous periclase-magnesium aluminate spinel refractory aggregate with high purity, nano-sized pores and core-shell structure, and the volume expansion generated when the magnesium aluminate spinel is formed compensates for the pores between the multi-porous magnesium oxide micro-particles, forming a dense magnesium aluminate spinel shell layer between the multi-porous magnesium oxide micro-particles, effectively reducing the internal stress of the product during high-temperature use, and improving the thermal shock stability of the aggregate. The aggregate has high purity, low impurity content, small amount of liquid phase at high temperature, stable structure at high temperature and excellent high-temperature service performance. The application prepares the multi-porous periclase-magnesium aluminate spinel refractory aggregate with continuous dense magnesium aluminate spinel shell wrapping the multi-porous periclase-magnesium aluminate spinel refractory aggregate, and forms the sawtooth occlusion interface structure at the shell-aggregate interface, so that the shell-aggregate interface is tightly combined. At the shell-matrix interface, the expansion generated when the magnesium aluminate spinel is formed forms the flaky graphite-magnesium aluminate spinel inlay structure, so that the shell-matrix is tightly combined, and the thermal shock stability and the erosion resistance of the product are improved.

[0032] The application adopts the multi-porous periclase refractory aggregate with nano-sized pores, the gas phase is not easy to penetrate, and the oxidation resistance of the lightweight periclase-magnesium aluminate spinel-carbon refractory material is improved. The sawtooth occlusion interface structure formed at the shell-aggregate interface makes the interface combination more tightly, and prevents the gas phase from penetrating along the shell-aggregate interface. The magnesium aluminate spinel in the inlay structure formed at the shell-matrix interface can hinder the oxidation of carbon at the interface by oxygen, and the oxidation resistance of the product is improved.

[0033] The application designs the raw material ratio, the raw material particle size and the forming pressure, prepares the structure with magnesium hydroxide micro-particles as the framework and the aluminum source with large particle size difference filled between the magnesium hydroxide micro-particles, adjusts the firing system and the micro-nano powder ratio, makes the volume expansion of the magnesium aluminate spinel compensate for the shrinkage of the multi-porous magnesium oxide micro-particles and the voids generated by the Kirkendall effect due to the mutual diffusion of Mg 2+ and Al 3 + , forms the dense magnesium aluminate spinel filled between the multi-porous magnesium oxide micro-particles, and prepares the multi-porous periclase-magnesium aluminate spinel refractory aggregate with the micro-core-shell structure of the continuous dense magnesium aluminate spinel shell tightly wrapping the multi-porous magnesium oxide core. The application designs the ratio of the aluminum source and the liquid thermosetting phenolic resin, makes the aluminum source uniformly dispersed in the liquid thermosetting phenolic resin, and modifies the liquid thermosetting phenolic resin to have good fluidity. The aluminum source is uniformly wrapped on the surface of the multi-porous periclase-magnesium aluminate spinel refractory aggregate. In the reaction sintering process, the sintering driving force is increased, the aluminum source reacts with the aggregate and the matrix to form the continuous dense magnesium aluminate spinel shell, the volume expansion generated in the magnesium aluminate spinel reaction process forms the tightly combined interfaces of the aggregate-shell and the shell-matrix, and the multi-scale core-shell structure is formed together with the core-shell structure in the aggregate, so that the erosion resistance, the thermal shock stability and the oxidation resistance of the refractory material are significantly improved.

[0034] The prepared lightweight periclase-magnesium aluminate spinel-carbon refractory material has a porosity of 20-30%, a bulk density of 2.38-2.72 g / cm 3 , and a compressive strength of 80-150 MPa.

[0035] Therefore, the prepared lightweight periclase-magnesium aluminate spinel-carbon refractory material with a multi-scale core-shell structure has the characteristics of low thermal conductivity, excellent thermal shock resistance, excellent erosion resistance, and good oxidation resistance. DETAILED DESCRIPTION

[0036] The application will be further described in conjunction with specific embodiments, but not limited to the scope of protection.

[0037] A lightweight periclase-magnesium aluminate spinel-carbon refractory material and a preparation method thereof. The preparation method comprises the following steps:

[0038] Step 1, preparation of a microporous periclase-magnesium aluminate spinel ceramic with a micro-core-shell structure

[0039] Step 1.1, using any one of alumina nano-powder, alumina micro-powder and aluminum hydroxide micro-powder as an aluminum source, or using a mixture of any two of alumina nano-powder, alumina micro-powder and aluminum hydroxide micro-powder as an aluminum source, or using a mixture of the three of alumina nano-powder, alumina micro-powder and aluminum hydroxide micro-powder as an aluminum source.

[0040] Step 1.2, placing 79-97 wt% of magnesium hydroxide fine powder and 3-21 wt% of the aluminum source in a blender, adding 4.5-5.5 wt% of water to the sum of the magnesium hydroxide fine powder and the aluminum source, and stirring for 1-3 h to obtain a mixture.

[0041] Step 1.3, molding the mixture under a pressure of 100-200 MPa, drying the molded body at 110-220 ℃ for 24-48 h, then placing the dried body in a high-temperature furnace, heating at a rate of 1-3 ℃ / min to 300-400 ℃, maintaining the temperature for 0.5-3 h, then heating at a rate of 3-5 ℃ / min to 1600-1800 ℃, maintaining the temperature for 3-8 h, and cooling with the furnace to obtain a microporous periclase-magnesium aluminate spinel ceramic with a micro-core-shell structure.

[0042] The microporous periclase-magnesium aluminum spinel ceramic with a micro-core-shell structure is crushed and sieved to obtain microporous periclase-magnesium aluminum spinel refractory aggregate I with a particle size of less than 5 mm and greater than or equal to 3 mm, microporous periclase-magnesium aluminum spinel refractory aggregate II with a particle size of less than 3 mm and greater than or equal to 1 mm, and microporous periclase-magnesium aluminum spinel refractory aggregate III with a particle size of less than 1 mm and greater than or equal to 0.1 mm.

[0043] The microporous periclase-magnesia-alumina spinel refractory aggregate has a total Al2O3 and MgO content > 99.55%, an apparent porosity of 15-30%, and a bulk density of 2.45-3.04 g / cm³. 3 The average pore size is 254–809 nm, the compressive strength is 60–130 MPa, and the thermal conductivity at 800℃ is 4.04–6.54 W / (m·K).

[0044] Step 2: Preparation of lightweight periclase-magnesia-alumina spinel-carbon refractory materials

[0045] The total aggregate consists of 20–25 wt% of the aforementioned microporous periclase-magnesia-alumina spinel refractory aggregate I, 18–23 wt% of the aforementioned microporous periclase-magnesia-alumina spinel refractory aggregate II, and 15–22 wt% of the aforementioned microporous periclase-magnesia-alumina spinel refractory aggregate III, with 31–45 wt% of magnesia fine powder, 0.1–1.5 wt% of elemental silica powder, and 0.5–3.5 wt% of flake graphite powder as the total matrix.

[0046] First, place the total aggregate in a mixer, add 2-6 wt% of modified liquid thermosetting phenolic resin (the sum of the total aggregate and the total matrix), and mix. Then, add the total matrix and stir evenly. Press the mixture under 150-200 MPa and keep it at 180-300℃ for 12-36 hours to obtain a lightweight periclase-magnesium aluminum spinel-carbon refractory material.

[0047] The modified liquid thermosetting phenolic resin is prepared by mixing the liquid thermosetting phenolic resin and the aluminum source evenly at a mass ratio of 100:(30-150) to obtain the modified liquid thermosetting phenolic resin.

[0048] The aluminum source mentioned in step 2 is the same as the aluminum source mentioned in step 1.

[0049] The alumina nanopowder has an Al2O3 content > 99 wt%.

[0050] The alumina micro powder has an Al2O3 content > 99 wt%.

[0051] The aluminum hydroxide micro powder has an Al2O3 content of 64–66 wt%.

[0052] The MgO content of the magnesium hydroxide fine powder is 64-66wt%.

[0053] The MgO content of the magnesia fine powder is 95-97wt%.

[0054] The Si content of the elemental silicon powder is 98-99.5wt%.

[0055] The C content of the flake graphite powder is 97-98.5wt%.

[0056] The carbon residue rate of the liquid thermosetting phenolic resin is ≥35%.

[0057] In the specific embodiment:

[0058] The particle size of the alumina nano-powder is <40nm;

[0059] The particle size of the alumina micro-powder is <2μm;

[0060] The particle size of the aluminum hydroxide micro-powder is <5μm;

[0061] The particle size of the magnesium hydroxide fine powder is <100μm;

[0062] The particle size of the magnesia fine powder is <88μm;

[0063] The particle size of the elemental silicon powder is <50μm;

[0064] The particle size of the flake graphite powder is <18μm;

[0065] The porous periclase-magnesia alumina spinel refractory aggregate I, the porous periclase-magnesia alumina spinel refractory aggregate II and the porous periclase-magnesia alumina spinel refractory aggregate III are collectively referred to as the porous periclase-magnesia alumina spinel refractory aggregate;

[0066] The porous periclase-magnesia alumina spinel refractory aggregate described in the specific embodiment has a micro-core-shell structure with a nano-pore-containing porous magnesium oxide micro-particle as the core and a continuous dense magnesia alumina spinel layer as the shell;

[0067] The lightweight periclase-magnesia alumina spinel-carbon refractory material described in the specific embodiment is a multi-scale core-shell structure with a porous periclase-magnesia alumina spinel refractory aggregate having a micro-core-shell structure with a nano-pore-containing porous magnesium oxide micro-particle as the core and a continuous dense magnesia alumina spinel layer as the shell as the core and a continuous alumina layer as the shell;

[0068] The embodiments are not described again.

[0069] The continuous alumina layer has a thickness of 0.1-0.3 mm; the microporous periclase-magnesium aluminate spinel refractory aggregate and the lightweight periclase-magnesium aluminate spinel-carbon refractory material have the following properties: the microporous magnesium oxide micro-particle has a particle size of 30-50 μm, and the continuous dense magnesium aluminate spinel layer has a thickness of 2-5 μm.

[0070] Embodiment 1

[0071] A lightweight periclase-magnesium aluminate spinel-carbon refractory material and a preparation method thereof. The preparation method of the embodiment has the following steps:

[0072] Step 1, preparation of microporous periclase-magnesium aluminate spinel ceramic with micro-core-shell structure

[0073] Step 1.1, using alumina micro-powder as the aluminum source.

[0074] Step 1.2, placing 97 wt% of magnesium hydroxide fine powder and 3 wt% of the aluminum source in a blender, adding 4.8 wt% of water to the sum of the magnesium hydroxide fine powder and the aluminum source, and stirring for 1 h to obtain a mixture.

[0075] Step 1.3, molding the mixture under the condition of 150 MPa, drying the molded body at 110℃ for 36 h, then placing the dried body in a high-temperature furnace, heating at a rate of 1.5℃ / min to 330℃, maintaining the temperature for 0.5 h, then heating at a rate of 3℃ / min to 1650℃, maintaining the temperature for 3 h, and cooling in the furnace to obtain microporous periclase-magnesium aluminate spinel ceramic with micro-core-shell structure.

[0076] The microporous periclase-magnesium aluminate spinel ceramic with micro-core-shell structure is crushed and sieved to obtain microporous periclase-magnesium aluminate spinel refractory aggregate I with a particle size of less than 5 mm and greater than or equal to 3 mm, microporous periclase-magnesium aluminate spinel refractory aggregate II with a particle size of less than 3 mm and greater than or equal to 1 mm, and microporous periclase-magnesium aluminate spinel refractory aggregate III with a particle size of less than 1 mm and greater than or equal to 0.1 mm.

[0077] The microporous periclase-magnesium aluminate spinel refractory aggregate has a total content of Al2O3 and MgO of >99.55%, an apparent porosity of 24.5%, a bulk density of 2.70 g / cm 3 , an average pore size of 423 nm, a compressive strength of 60 MPa, and a thermal conductivity of 5.23 W / (m·K) at 800℃.

[0078] Step 2, preparation of lightweight periclase-magnesium aluminate spinel-carbon refractory material

[0079] The total aggregate consists of 25 wt% of the aforementioned microporous periclase-magnesia-alumina spinel refractory aggregate I, 23 wt% of the aforementioned microporous periclase-magnesia-alumina spinel refractory aggregate II, and 16 wt% of the aforementioned microporous periclase-magnesia-alumina spinel refractory aggregate III, with 32 wt% of magnesia fine powder, 0.5 wt% of elemental silica powder, and 3.5 wt% of flake graphite powder as the total matrix.

[0080] First, place the total aggregate in a mixer, add 2wt% of modified liquid thermosetting phenolic resin (the sum of the total aggregate and the total matrix), and mix. Then, add the total matrix and stir evenly. Press the mixture under 150 MPa and keep it at 180°C for 36 hours to obtain a lightweight periclase-magnesium aluminum spinel-carbon refractory material.

[0081] The modified liquid thermosetting phenolic resin is prepared by mixing the liquid thermosetting phenolic resin and the aluminum source evenly according to the mass ratio of liquid thermosetting phenolic resin to the aluminum source of 100:30 to obtain the modified liquid thermosetting phenolic resin.

[0082] The aluminum source mentioned in step 2 is the same as the aluminum source mentioned in step 1.

[0083] The alumina micro powder has an Al2O3 content of 99.3 wt%.

[0084] The MgO content of the fine magnesium hydroxide powder is 65.1 wt%.

[0085] The MgO content of the fine magnesia powder is 95 wt%.

[0086] The elemental silicon powder has a Si content of 99.2 wt%.

[0087] The carbon content of the flake graphite powder is 97 wt%.

[0088] The residual carbon rate of the liquid thermosetting phenolic resin is 39.8%.

[0089] The lightweight periclase-magnesia-alumina spinel-carbon refractory material prepared by this invention was tested and found to have an apparent porosity of 20% and a bulk density of 2.72 g / cm³. 3 The compressive strength is 80 MPa.

[0090] Example 2

[0091] A lightweight periclase-magnesium aluminum spinel-carbon refractory material and its preparation method. The preparation method described in this embodiment is as follows:

[0092] Step 1: Preparation of microporous periclase-magnesium aluminum spinel ceramics with micro-core-shell structure

[0093] Step 1.1: Use alumina nanoparticles as the aluminum source.

[0094] Step 1.2, put 91wt% of magnesium hydroxide fine powder and 9wt% of aluminum source into a blender, plus 4.5wt% of water of the sum of the magnesium hydroxide fine powder and the aluminum source, stir for 3h, to obtain a mixture.

[0095] Step 1.3, the mixture is molded under the condition of 160MPa, and then the molded body is dried at 150℃ for 24h; then the dried body is placed in a high temperature furnace, heated to 300℃ at a rate of 3℃ / min, kept for 0.8h, then heated to 1600℃ at a rate of 3.8℃ / min, kept for 5h, and cooled in the furnace to obtain a microporous periclase-magnesium aluminate spinel ceramic with a micro-nucleus shell structure.

[0096] The microporous periclase-magnesium aluminate spinel refractory aggregate I with a particle size of less than 5mm and greater than or equal to 3mm, the microporous periclase-magnesium aluminate spinel refractory aggregate II with a particle size of less than 3mm and greater than or equal to 1mm, and the microporous periclase-magnesium aluminate spinel refractory aggregate III with a particle size of less than 1mm and greater than or equal to 0.1mm are obtained by crushing and sieving the microporous periclase-magnesium aluminate spinel ceramic with a micro-nucleus shell structure.

[0097] The total content of Al2O3 and MgO in the microporous periclase-magnesium aluminate spinel refractory aggregate is >99.55%, the apparent porosity is 30%, the bulk density is 2.45g / cm 3 , the average pore size is 267nm, the compressive strength is 120MPa, and the thermal conductivity at 800℃ is 4.04W / (m·K).

[0098] Step 2, preparation of lightweight periclase-magnesium aluminate spinel-carbon refractory material

[0099] The total aggregate is placed in a blender, plus 3.9wt% of modified liquid thermosetting phenolic resin of the sum of the total aggregate and the total matrix, mixed; then the total matrix is added and stirred uniformly; molded under the condition of 180MPa, and heat treated at 220℃ for 21h to obtain a lightweight periclase-magnesium aluminate spinel-carbon refractory material.

[0100] The total aggregate is placed in a blender, plus 3.9wt% of modified liquid thermosetting phenolic resin of the sum of the total aggregate and the total matrix, mixed; then the total matrix is added and stirred uniformly; molded under the condition of 180MPa, and heat treated at 220℃ for 21h to obtain a lightweight periclase-magnesium aluminate spinel-carbon refractory material.

[0101] The preparation method of the modified liquid thermosetting phenolic resin is as follows: the liquid thermosetting phenolic resin and the aluminum source are uniformly mixed according to the mass ratio of 100:100 of the liquid thermosetting phenolic resin to the aluminum source, and the modified liquid thermosetting phenolic resin is obtained.

[0102] The aluminum source in step 2 is the same as the aluminum source in step 1.

[0103] The Al2O3 content of the aluminum oxide nanopowder is 99.6wt%.

[0104] The MgO content of the magnesium hydroxide fine powder is 66wt%.

[0105] The MgO content of the magnesia fine powder is 97wt%.

[0106] The Si content of the elemental silicon powder is 98wt%.

[0107] The C content of the flake graphite powder is 98.2wt%.

[0108] The carbon residue rate of the liquid thermosetting phenolic resin is 35%.

[0109] The lightweight periclase-magnesium aluminate spinel-carbon refractory material prepared by the method has a porosity of 25%, a bulk density of 2.55g / cm 3 , and a compressive strength of 121MPa.

[0110] Example 3

[0111] A lightweight periclase-magnesium aluminate spinel-carbon refractory material and a preparation method thereof.

[0112] Step 1, preparation of a microporous periclase-magnesium aluminate spinel ceramic with a microcore-shell structure

[0113] Step 1.1, using aluminum hydroxide powder as the aluminum source.

[0114] Step 1.2, placing 96wt% of magnesium hydroxide fine powder and 4wt% of the aluminum source in a blender, adding 5.2wt% of water to the sum of the magnesium hydroxide fine powder and the aluminum source, and stirring for 2h to obtain a mixture.

[0115] Step 1.3, molding the mixture under the condition of 120MPa, drying the molded body at 200℃ for 31h, then placing the dried body in a high-temperature furnace, heating at a rate of 2.1℃ / min to 350℃, maintaining the temperature for 2h, then heating at a rate of 4.2℃ / min to 1620℃, maintaining the temperature for 8h, and cooling in the furnace to obtain a microporous periclase-magnesium aluminate spinel ceramic with a microcore-shell structure.

[0116] The multi-microporous periclase-magnesium aluminate spinel ceramic with the micro-nuclear shell structure is broken and sieved to obtain multi-microporous periclase-magnesium aluminate spinel refractory aggregate I with a particle size less than 5 mm and greater than or equal to 3 mm, multi-microporous periclase-magnesium aluminate spinel refractory aggregate II with a particle size less than 3 mm and greater than or equal to 1 mm, and multi-microporous periclase-magnesium aluminate spinel refractory aggregate III with a particle size less than 1 mm and greater than or equal to 0.1 mm.

[0117] The total content of Al2O3 and MgO in the multi-microporous periclase-magnesium aluminate spinel refractory aggregate is greater than 99.55%, the apparent porosity is 29.4%, the bulk density is 2.48 g / cm 3 , the average pore size is 502 nm, the compressive strength is 80 MPa, and the thermal conductivity at 800 DEG C is 4.00 W / (m·K).

[0118] Step 2, preparation of lightweight periclase-magnesium aluminate spinel-carbon refractory material

[0119] The total aggregate is placed in a blender, and 4.2 wt% of the modified liquid thermosetting phenolic resin is added to the total aggregate and the total matrix, mixed, then the total matrix is added and stirred uniformly, and then the lightweight periclase-magnesium aluminate spinel-carbon refractory material is prepared by molding under the condition of 200 MPa and heat preservation at 250 DEG C for 24 h.

[0120] The preparation method of the modified liquid thermosetting phenolic resin is as follows: the liquid thermosetting phenolic resin and the aluminum source are uniformly mixed according to a mass ratio of 100:80 of the liquid thermosetting phenolic resin to the aluminum source to obtain the modified liquid thermosetting phenolic resin.

[0121] The aluminum source in step 2 is the same as the aluminum source in step 1.

[0122] The Al2O3 content of the aluminum hydroxide powder is 64 wt%.

[0123] The MgO content of the magnesium hydroxide powder is 64 wt%.

[0124] The MgO content of the magnesium hydroxide powder is 64 wt%.

[0125] The Si content of the elemental silicon powder is 98.9 wt%.

[0126] The Si content of the elemental silicon powder is 98.9 wt%.

[0127] The C content of the flaky graphite powder is 98.5wt%.

[0128] The carbon residue rate of the liquid thermosetting phenolic resin is 36.4%.

[0129] The lightweight periclase-magnesium aluminate spinel-carbon refractory material prepared by the method has the following properties: an apparent porosity of 23%, a bulk density of 2.62 g / cm 3 , and a compressive strength of 135 MPa.

[0130] Example 4

[0131] A lightweight periclase-magnesium aluminate spinel-carbon refractory material and a preparation method thereof.

[0132] Step 1, preparation of a microporous periclase-magnesium aluminate spinel ceramic with a microcore-shell structure

[0133] Step 1.1, using a mixture of alumina nano-powder and alumina micro-powder as the aluminum source.

[0134] Step 1.2, placing 85wt% of magnesium hydroxide fine powder and 15wt% of the aluminum source in a blender, adding 5.5wt% of water to the sum of the magnesium hydroxide fine powder and the aluminum source, and stirring for 3h to obtain a mixture.

[0135] Step 1.3, molding the mixture under a pressure of 200MPa, drying the molded body at 180℃ for 40h, then placing the dried body in a high-temperature furnace, heating at a rate of 3℃ / min to 400℃, maintaining the temperature for 1h, then heating at a rate of 3.6℃ / min to 1800℃, maintaining the temperature for 4h, and cooling in the furnace to obtain the microporous periclase-magnesium aluminate spinel ceramic with a microcore-shell structure.

[0136] The microporous periclase-magnesium aluminate spinel ceramic with a microcore-shell structure is crushed and sieved to obtain microporous periclase-magnesium aluminate spinel refractory aggregate I with a particle size of less than 5mm and greater than or equal to 3mm, microporous periclase-magnesium aluminate spinel refractory aggregate II with a particle size of less than 3mm and greater than or equal to 1mm, and microporous periclase-magnesium aluminate spinel refractory aggregate III with a particle size of less than 1mm and greater than or equal to 0.1mm.

[0137] The microporous periclase-magnesium aluminate spinel refractory aggregate has a total content of Al2O3 and MgO of >99.55%, an apparent porosity of 15%, a bulk density of 3.04g / cm 3 , an average pore size of 645nm, a compressive strength of 130MPa, and a thermal conductivity of 6.54W / (m·K) at 800℃.

[0138] Step 2, preparation of lightweight periclase-magnesia alumina spinel-carbon refractory

[0139] The total matrix is composed of 36wt% magnesia fine powder, 0.1wt% elemental silicon powder and 0.9wt% flake graphite powder.

[0140] The total matrix is composed of 36wt% magnesia fine powder, 0.1wt% elemental silicon powder and 0.9wt% flake graphite powder.

[0141] The preparation method of the modified liquid thermosetting phenolic resin is as follows: the liquid thermosetting phenolic resin and the aluminum source are uniformly mixed according to the mass ratio of liquid thermosetting phenolic resin: aluminum source = 100:150 to obtain the modified liquid thermosetting phenolic resin.

[0142] The aluminum source in step 2 is the same as the aluminum source in step 1.

[0143] The Al2O3 content of the alumina nano-powder is 99.8wt%.

[0144] The Al2O3 content of the alumina nano-powder is 99.8wt%.

[0145] The MgO content of the magnesium hydroxide fine powder is 65.6wt%.

[0146] The MgO content of the magnesium hydroxide fine powder is 65.6wt%.

[0147] The Si content of the elemental silicon powder is 98.5wt%.

[0148] The C content of the flake graphite powder is 97.7wt%.

[0149] The residual carbon rate of the liquid thermosetting phenolic resin is 38%.

[0150] The lightweight periclase-magnesia alumina spinel-carbon refractory prepared in the application is detected: the apparent porosity is 28%; the bulk density is 2.45g / cm 3 ; the compressive strength is 110MPa.

[0151] Example 5

[0152] A lightweight periclase-magnesia-alumina spinel-carbon refractory material and a preparation method thereof. The preparation method of the embodiment is as follows:

[0153] Step 1, preparation of a microporous periclase-magnesia-alumina spinel ceramic with a micro-nucleus shell structure

[0154] Step 1.1, using a mixture of alumina nanopowder and aluminum hydroxide micropowder as the aluminum source.

[0155] Step 1.2, placing 87wt% of magnesium hydroxide fine powder and 13wt% of the aluminum source in a blender, adding 5.1wt% of water to the sum of the magnesium hydroxide fine powder and the aluminum source, and stirring for 2h to obtain a mixture.

[0156] Step 1.3, molding the mixture under a pressure of 140MPa, drying the molded body at 140℃ for 42h, then placing the dried body in a high-temperature furnace, heating at a rate of 1℃ / min to 380℃, maintaining the temperature for 1.6h, then heating at a rate of 5℃ / min to 1780℃, maintaining the temperature for 6h, and cooling in the furnace to obtain a microporous periclase-magnesia-alumina spinel ceramic with a micro-nucleus shell structure.

[0157] The microporous periclase-magnesia-alumina spinel ceramic with a micro-nucleus shell structure is crushed and sieved to obtain a microporous periclase-magnesia-alumina spinel refractory aggregate I with a particle size of less than 5mm and greater than or equal to 3mm, a microporous periclase-magnesia-alumina spinel refractory aggregate II with a particle size of less than 3mm and greater than or equal to 1mm, and a microporous periclase-magnesia-alumina spinel refractory aggregate III with a particle size of less than 1mm and greater than or equal to 0.1mm.

[0158] The microporous periclase-magnesia-alumina spinel refractory aggregate has a total content of Al2O3 and MgO of >99.55%, an apparent porosity of 16%, a bulk density of 3.00g / cm 3 , an average pore size of 764nm, a compressive strength of 124MPa, and a thermal conductivity of 6.29W / (m·K) at 800℃.

[0159] Step 2, preparation of a lightweight periclase-magnesia-alumina spinel-carbon refractory material

[0160] Using 24wt% of the microporous periclase-magnesia-alumina spinel refractory aggregate I, 21wt% of the microporous periclase-magnesia-alumina spinel refractory aggregate II, and 18wt% of the microporous periclase-magnesia-alumina spinel refractory aggregate III as total aggregate, and using 35wt% of magnesia fine powder, 1.5wt% of elemental silicon powder, and 0.5wt% of flake graphite powder as total matrix.

[0161] The total aggregate is first placed in a mixer, 4.8wt% of the modified liquid thermosetting phenolic resin of the sum of the total aggregate and the total matrix is added, mixed; then the total matrix is added and stirred uniformly; machine pressing is carried out under the condition of 170MPa, and the lightweight periclase-magnesium aluminate spinel-carbon refractory material is prepared by keeping at 280℃ for 12h.

[0162] The preparation method of the modified liquid thermosetting phenolic resin is as follows: the liquid thermosetting phenolic resin and the aluminum source are uniformly mixed according to the mass ratio of the liquid thermosetting phenolic resin to the aluminum source of 100:60, to obtain the modified liquid thermosetting phenolic resin.

[0163] The aluminum source in step 2 is the same as the aluminum source in step 1.

[0164] The Al2O3 content of the alumina nano powder is 99.2wt%.

[0165] The Al2O3 content of the aluminum hydroxide micro powder is 64.8wt%.

[0166] The MgO content of the magnesium hydroxide fine powder is 65.7wt%.

[0167] The MgO content of the magnesia fine powder is 96.3wt%.

[0168] The Si content of the elemental silicon powder is 98.3wt%.

[0169] The C content of the flake graphite powder is 98.4wt%.

[0170] The carbon residue rate of the liquid thermosetting phenolic resin is 35.6%.

[0171] The lightweight periclase-magnesium aluminate spinel-carbon refractory material prepared by the preparation method has the following properties: the apparent porosity is 28.8%; the bulk density is 2.49g / cm 3 ; and the compressive strength is 95MPa.

[0172] Example 6

[0173] A lightweight periclase-magnesium aluminate spinel-carbon refractory material and a preparation method thereof.

[0174] Step 1, preparation of a microporous periclase-magnesium aluminate spinel ceramic with a micro-core-shell structure

[0175] Step 1.1, using the mixed powder of the alumina micro powder and the aluminum hydroxide micro powder as the aluminum source.

[0176] Step 1.2, 82wt% of magnesium hydroxide fine powder and 18wt% of aluminum source were placed in a blender, 4.6wt% of water was added to the total weight of the magnesium hydroxide fine powder and the aluminum source, and stirred for 1h to obtain a mixture.

[0177] Step 1.3, the mixture was molded under the condition of 180MPa, and then the molded body was dried at 130℃ for 28h; then the dried body was placed in a high-temperature furnace, heated to 340℃ at a rate of 1.8℃ / min, kept for 3h, then heated to 1750℃ at a rate of 4.8℃ / min, kept for 7h, and cooled in the furnace to obtain a microporous periclase-magnesium aluminate spinel ceramic with a micro-nucleus shell structure.

[0178] The microporous periclase-magnesium aluminate spinel ceramic with a micro-nucleus shell structure was crushed and sieved to obtain microporous periclase-magnesium aluminate spinel refractory aggregate I with a particle size of less than 5mm and greater than or equal to 3mm, microporous periclase-magnesium aluminate spinel refractory aggregate II with a particle size of less than 3mm and greater than or equal to 1mm, and microporous periclase-magnesium aluminate spinel refractory aggregate III with a particle size of less than 1mm and greater than or equal to 0.1mm.

[0179] The total content of Al2O3 and MgO in the microporous periclase-magnesium aluminate spinel refractory aggregate was >99.55%, the apparent porosity was 18%, the bulk density was 2.98g / cm 3 , the average pore size was 809nm, the compressive strength was 116MPa, and the thermal conductivity at 800℃ was 6.04W / (m·K).

[0180] Step 2, preparation of lightweight periclase-magnesium aluminate spinel-carbon refractory material

[0181] 22wt% of the microporous periclase-magnesium aluminate spinel refractory aggregate I, 22wt% of the microporous periclase-magnesium aluminate spinel refractory aggregate II, and 22wt% of the microporous periclase-magnesium aluminate spinel refractory aggregate III were used as total aggregate, and 31wt% of magnesia fine powder, 0.9wt% of elemental silicon powder, and 2.1wt% of flake graphite powder were used as total matrix.

[0182] First, the total aggregate was placed in a blender, and 5.3wt% of modified liquid thermosetting phenolic resin was added to the total weight of the total aggregate and the total matrix, and mixed; then the total matrix was added and stirred uniformly; molded under the condition of 150MPa, and dried at 200℃ for 19h to obtain a lightweight periclase-magnesium aluminate spinel-carbon refractory material.

[0183] The preparation method of the modified liquid thermosetting phenolic resin is as follows: the liquid thermosetting phenolic resin and the aluminum source are uniformly mixed according to the mass ratio of the liquid thermosetting phenolic resin to the aluminum source being 100:120, so that the modified liquid thermosetting phenolic resin is obtained.

[0184] The aluminum source in step 2 is the same as the aluminum source in step 1.

[0185] The Al2O3 content of the aluminum oxide micropowder is 99.1wt%.

[0186] The Al2O3 content of the aluminum hydroxide micropowder is 66wt%.

[0187] The MgO content of the magnesium hydroxide micropowder is 64.6wt%.

[0188] The MgO content of the magnesia micropowder is 95.1wt%.

[0189] The Si content of the elemental silicon powder is 99.5wt%.

[0190] The C content of the flake graphite powder is 97.2wt%.

[0191] The carbon residue rate of the liquid thermosetting phenolic resin is 41.5%.

[0192] The lightweight periclase-magnesium aluminate spinel-carbon refractory material prepared by the method has a porosity of 28.2%, a bulk density of 2.44g / cm 3 , and a compressive strength of 108MPa.

[0193] Example 7

[0194] A lightweight periclase-magnesium aluminate spinel-carbon refractory material and a preparation method thereof.

[0195] Step 1, preparation of a microporous periclase-magnesium aluminate spinel ceramic with a microcore-shell structure

[0196] Step 1.1, using a mixture of aluminum oxide nanopowder, aluminum oxide micropowder and aluminum hydroxide micropowder as the aluminum source.

[0197] Step 1.2, placing 79wt% of magnesium hydroxide micropowder and 21wt% of the aluminum source in a blender, adding 5.3wt% of water to the sum of the magnesium hydroxide micropowder and the aluminum source, and stirring for 3h to obtain a mixture.

[0198] Step 1.3: Press the mixture into shape under 100 MPa, and then dry the shaped green body at 220℃ for 48 hours; then place the dried green body in a high-temperature furnace, heat it to 320℃ at a rate of 2.6℃ / min, hold it at that temperature for 2.4 hours, then heat it to 1700℃ at a rate of 3.3℃ / min, hold it at that temperature for 6 hours, and then cool it with the furnace to obtain a microporous periclase-magnesium aluminum spinel ceramic with a micro core-shell structure.

[0199] The microporous periclase-magnesium aluminum spinel ceramic with a micro-core-shell structure is crushed and sieved to obtain microporous periclase-magnesium aluminum spinel refractory aggregate I with a particle size of less than 5 mm and greater than or equal to 3 mm, microporous periclase-magnesium aluminum spinel refractory aggregate II with a particle size of less than 3 mm and greater than or equal to 1 mm, and microporous periclase-magnesium aluminum spinel refractory aggregate III with a particle size of less than 1 mm and greater than or equal to 0.1 mm.

[0200] The microporous periclase-magnesia-alumina spinel refractory aggregate has a total Al2O3 and MgO content > 99.55%, an apparent porosity of 16.9%, and a bulk density of 3.01 g / cm³. 3 It has an average pore size of 723 nm, a pressure resistance of 110 MPa, and a thermal conductivity of 6.02 W / (m·K) at 800℃.

[0201] Step 2: Preparation of lightweight periclase-magnesia-alumina spinel-carbon refractory materials

[0202] The total aggregate consists of 23 wt% of the aforementioned microporous periclase-magnesia-alumina spinel refractory aggregate I, 22 wt% of the aforementioned microporous periclase-magnesia-alumina spinel refractory aggregate II, and 21 wt% of the aforementioned microporous periclase-magnesia-alumina spinel refractory aggregate III, with 31 wt% of magnesia fine powder, 1.5 wt% of elemental silica powder, and 1.5 wt% of flake graphite powder as the total matrix.

[0203] First, place the total aggregate in a mixer, add 6 wt% of modified liquid thermosetting phenolic resin (the sum of the total aggregate and the total matrix), and mix. Then, add the total matrix and stir evenly. Press the mixture under 160 MPa and keep it at 270°C for 32 hours to obtain a lightweight periclase-magnesium aluminum spinel-carbon refractory material.

[0204] The modified liquid thermosetting phenolic resin is prepared by mixing the liquid thermosetting phenolic resin and the aluminum source evenly according to the mass ratio of liquid thermosetting phenolic resin to aluminum source of 100:130 to obtain the modified liquid thermosetting phenolic resin.

[0205] The aluminum source mentioned in step 2 is the same as the aluminum source mentioned in step 1.

[0206] The Al2O3 content of the alumina nanopowder is 99.7wt%.

[0207] The Al2O3 content of the alumina micropowder is 99.7wt%.

[0208] The Al2O3 content of the aluminum hydroxide micropowder is 65.5wt%.

[0209] The MgO content of the magnesium hydroxide micropowder is 64.9wt%.

[0210] The MgO content of the magnesia micropowder is 96.5wt%.

[0211] The Si content of the elemental silicon powder is 99wt%.

[0212] The C content of the flake graphite powder is 97.6wt%.

[0213] The carbon residue rate of the liquid thermosetting phenolic resin is 42%.

[0214] The lightweight periclase-magnesium aluminate spinel-carbon refractory material prepared in the application is detected to have a porosity of 30%, a bulk density of 2.38g / cm 3 , and a compressive strength of 150MPa.

[0215] Compared with the prior art, the specific embodiment has the following positive effects:

[0216] The present specific embodiment designs the whole process from raw materials to refractory aggregate to refractory material. In the aspect of aggregate, the multi-microporous magnesia micro-particles with nano-pores are formed by in-situ decomposition of magnesium hydroxide as the core, a continuous and dense magnesium aluminate spinel layer is formed by introducing special particle size of aluminum source, in-situ reaction and process as the shell, and the multi-microporous periclase-magnesium aluminate spinel refractory aggregate with micro-core-shell structure and precisely controlled distribution of magnesium aluminate spinel is obtained. The particle size of the multi-microporous magnesia micro-particles is 20-45 μm, and the thickness of the continuous and dense magnesium aluminate spinel layer is 2-5 μm. Compared with the prior art, the prepared aggregate has high purity, stable high-temperature structure, low thermal conductivity, and excellent high-temperature service performance. In the light-weight periclase-magnesium aluminate spinel-carbon refractory material, the special particle size of aluminum source is wrapped on the surface of the aggregate with micro-core-shell structure to form a continuous alumina layer of 0.1-0.3 mm, and then in-situ decomposition synthesis method is used to form a magnesium aluminate spinel layer under the conditions of carbon-embedded atmosphere and 1200-1400 °C. On the one hand, a flake graphite-magnesium aluminate spinel inlaid structure is formed at the shell-matrix interface, and on the other hand, a serrated occlusion-like interface structure is formed at the shell-aggregate interface, which together with the multi-microporous periclase-magnesium aluminate spinel refractory aggregate with micro-core-shell structure forms a multi-scale core-shell structure, and fully plays the advantages of nano-pores, magnesia, magnesium aluminate spinel and flake graphite. The problems of high thermal conductivity, poor thermal shock stability and poor erosion resistance of the existing dense periclase-magnesium aluminate spinel-carbon refractory material are overcome, and the problem of large pore size and poor oxidation resistance of the existing light-weight periclase-magnesium aluminate spinel-carbon refractory material due to many impurities in the aggregate is solved.

[0217] The present specific embodiment uses the multi-microporous periclase-magnesium aluminate spinel refractory aggregate with nano-pores and core-shell structure with high purity, and uses the volume expansion generated during the formation of magnesium aluminate spinel to compensate for the pores between the multi-microporous magnesia micro-particles, to form a dense magnesium aluminate spinel shell layer between the multi-microporous magnesia micro-particles inside the aggregate, effectively reducing the internal stress of the product during high-temperature use, and improving the thermal shock stability of the aggregate. The aggregate has high purity, low impurity content, less liquid phase at high temperature, stable structure at high temperature and excellent high-temperature service performance. The present specific embodiment prepares a continuous and dense magnesium aluminate spinel shell to wrap the multi-microporous periclase-magnesium aluminate spinel refractory aggregate, forms a serrated occlusion-like interface structure at the shell-aggregate interface, and makes the shell-aggregate interface tightly combined. At the shell-matrix interface, the expansion generated during the formation of magnesium aluminate spinel forms a flake graphite-magnesium aluminate spinel inlaid structure, making the shell-matrix tightly combined, which together improves the thermal shock stability and erosion resistance of the product.

[0218] The embodiment adopts a porous magnesia refractory aggregate with nanoscale pores, and the gas phase is not easy to penetrate, thereby improving the oxidation resistance of the lightweight magnesia-magnesium aluminate spinel-carbon refractory material. The sawtooth occlusion interface structure formed at the shell-aggregate interface makes the interface combination more compact, and prevents the gas phase from penetrating along the shell-aggregate interface; the magnesium aluminate spinel in the inlaid structure formed at the shell-matrix interface can hinder the oxidation of carbon at the interface by oxygen, and both of them improve the oxidation resistance of the product.

[0219] The embodiment prepares a structure in which magnesium hydroxide microparticles are used as a skeleton, and aluminum sources with large particle size differences are filled between the magnesium hydroxide microparticles, by designing the raw material ratio, raw material particle size and forming pressure. By adjusting the firing system and the ratio of micro-nano powder, the volume expansion of the magnesium aluminate spinel compensates for the shrinkage of the porous magnesium oxide microparticles and the voids caused by the Kirkendall effect due to the mutual diffusion of Mg 2+ and Al 3+ , so that a dense magnesium aluminate spinel is filled between the porous magnesium oxide microparticles, and the prepared porous magnesia-magnesium aluminate spinel refractory aggregate has a micro-nucleus-shell structure in which a continuous dense magnesium aluminate spinel shell tightly wraps a porous magnesium oxide core. The ratio of the aluminum source and the liquid thermosetting phenolic resin is designed, so that the aluminum source can be uniformly dispersed in the liquid thermosetting phenolic resin, and the modified liquid thermosetting phenolic resin has good fluidity. The aluminum source is uniformly wrapped on the surface of the porous magnesia-magnesium aluminate spinel refractory aggregate. In the reaction sintering process, the sintering driving force is increased, so that the aluminum source reacts with the aggregate and the matrix respectively to form a continuous dense magnesium aluminate spinel shell. Through the volume expansion formed in the magnesium aluminate spinel reaction process, a tightly combined interface of the aggregate-shell and the shell-matrix is formed, and together with the core-shell structure in the aggregate, a multi-scale core-shell structure is formed, which significantly improves the erosion resistance, thermal shock stability and oxidation resistance of the refractory material.

[0220] The lightweight magnesia-magnesium aluminate spinel-carbon refractory material prepared in the embodiment is detected to have an apparent porosity of 20-30%, a bulk density of 2.38-2.72 g / cm 3 , and a compressive strength of 80-150 MPa.

[0221] Therefore, the lightweight magnesia-magnesium aluminate spinel-carbon refractory material with a multi-scale core-shell structure prepared in the embodiment has the characteristics of low thermal conductivity, excellent thermal shock stability, excellent erosion resistance and good oxidation resistance.

Claims

1. A method for producing a lightweight magnesia-magnesium aluminate spinel-carbon refractory material, characterized in that The steps of the preparation method are: Step 1, preparation of a multi-microporous periclase-magnesia-alumina spinel ceramic with a micro-nucleus-shell structure Step 1.1, using any one of alumina nanopowder, alumina micropowder and aluminum hydroxide micropowder as the aluminum source, or using any two of the mixed powders of alumina nanopowder, alumina micropowder and aluminum hydroxide micropowder as the aluminum source, or using the mixed powders of the three of alumina nanopowder, alumina micropowder and aluminum hydroxide micropowder as the aluminum source; Step 1.2, placing 79-97wt% of magnesium hydroxide fine powder and 3-21wt% of the aluminum source in a blender, adding 4.5-5.5wt% of water to the sum of the magnesium hydroxide fine powder and the aluminum source, and stirring for 1-3h to obtain a mixture; Step 1.3, molding the mixture under the condition of 100-200MPa, then drying the molded body at 110-220℃ for 24-48h; then placing the dried body in a high-temperature furnace, heating at a rate of 1-3℃ / min to 300-400℃, maintaining the temperature for 0.5-3h, then heating at a rate of 3-5℃ / min to 1600-1800℃, maintaining the temperature for 3-8h, and cooling in the furnace to obtain a multi-microporous periclase-magnesia-alumina spinel ceramic with a micro-nucleus-shell structure; Breaking and sieving the multi-microporous periclase-magnesia-alumina spinel ceramic with a micro-nucleus-shell structure; Obtaining a multi-microporous periclase-magnesia-alumina spinel refractory aggregate I with a particle size less than 5mm and greater than or equal to 3mm, a multi-microporous periclase-magnesia-alumina spinel refractory aggregate II with a particle size less than 3mm and greater than or equal to 1mm, and a multi-microporous periclase-magnesia-alumina spinel refractory aggregate III with a particle size less than 1mm and greater than or equal to 0.1mm, respectively; The multi-microporous periclase-magnesia-alumina spinel refractory aggregate has a micro-nucleus-shell structure with a microporous magnesium oxide microparticle containing nanopores as the nucleus and a continuous dense magnesia-alumina spinel layer as the shell; the particle size of the microporous magnesium oxide microparticle is 20-45μm, and the thickness of the continuous dense magnesia-alumina spinel layer is 2-5μm; the multi-microporous periclase-magnesia-alumina spinel refractory aggregate has a total content of Al2O3 and MgO >99.55%, an apparent porosity of 15-30%, a bulk density of 2.45-3.04g / cm3, an average pore size of 254-809nm, a compressive strength of 60-130MPa, and a thermal conductivity of 4.04-6.54W / (m·K) at 800℃; Step 2, preparation of a lightweight periclase-magnesia-alumina spinel-carbon refractory material Using 20-25wt% of the multi-microporous periclase-magnesia-alumina spinel refractory aggregate I, 18-23wt% of the multi-microporous periclase-magnesia-alumina spinel refractory aggregate II and 15-22wt% of the multi-microporous periclase-magnesia-alumina spinel refractory aggregate III as the total aggregate, and using 31-45wt% of magnesia fine powder, 0.1-1.5wt% of elemental silicon powder and 0.5-3.5wt% of flake graphite powder as the total matrix; The total aggregate is first placed in a mixer, 2-6 wt% of the sum of the total aggregate and the total matrix of modified liquid thermosetting phenolic resin is added, mixed; then the total matrix is added and stirred uniformly; machine pressing is performed under the condition of 150-200 MPa, and heat preservation is performed under the condition of 180-300 ℃ for 12-36 h to obtain the lightweight periclase-magnesium aluminate spinel-carbon refractory material; The preparation method of the modified liquid thermosetting phenolic resin is as follows: the mass ratio of liquid thermosetting phenolic resin to the aluminum source is 100: (30-150), the liquid thermosetting phenolic resin and the aluminum source are uniformly mixed to obtain the modified liquid thermosetting phenolic resin; The aluminum source in step 2 is the same as the aluminum source in step 1. The particle size of the alumina nano powder is <40 nm. The particle size of the alumina micro powder is <2 μm. The particle size of the aluminum hydroxide micro powder is <5 μm. The particle size of the magnesium hydroxide fine powder is <100 μm.

2. The production method of the lightweight periclase-magnesio-alumina spinel-carbon refractory material according to claim 1, characterized in that The Al2O3 content of the alumina nano powder is >99 wt%.

3. The method of producing a lightweight periclase-magnesio-alumina spinel-carbon refractory material according to claim 1, characterized in that The Al2O3 content of the alumina micro powder is >99 wt%.

4. The method of producing a lightweight periclase-magnesio-alumina spinel-carbon refractory material according to claim 1, characterized in that The Al2O3 content of the aluminum hydroxide micro powder is 64-66 wt%.

5. The method of producing a lightweight magnesia-magnesia-alumina spinel-carbon refractory material according to claim 1, characterized in that The MgO content of the magnesium hydroxide fine powder is 64-66 wt%.

6. The method of producing a lightweight magnesia-magnesia-alumina spinel-carbon refractory material according to claim 1, characterized in that The particle size of the magnesia fine powder is <88 μm; and the MgO content of the magnesia fine powder is 95-97 wt%.

7. The method of producing a lightweight magnesia-magnesia-alumina spinel-carbon refractory material according to claim 1, characterized in that The particle size of the elemental silicon powder is <50 μm; and the Si content of the elemental silicon powder is 98-99.5 wt%.

8. The method of producing a lightweight magnesia-magnesia-alumina spinel-carbon refractory material according to claim 1, characterized in that The particle size of the flake graphite powder is <18 μm; and the C content of the flake graphite powder is 97-98.5 wt%.

9. The method of producing a lightweight magnesia-magnesia-alumina spinel-carbon refractory material according to claim 1, characterized in that The carbon residue rate of the liquid thermosetting phenolic resin is ≥35%.

10. A lightweight magnesia-magnesia-alumina spinel-carbon refractory material, characterized in that The lightweight periclase-magnesium aluminate spinel-carbon refractory material is prepared according to the preparation method of the lightweight periclase-magnesium aluminate spinel-carbon refractory material in any one of claims 1-9. The lightweight periclase-magnesium aluminate spinel-carbon refractory material has a multi-microporous periclase-magnesium aluminate spinel refractory aggregate with a micro-nucleus-shell structure taking the microporous magnesium oxide micro-particle containing nano-pores as a core and the continuous dense magnesium aluminate spinel layer as a shell as a core and a multi-scale nucleus-shell structure taking the continuous alumina layer as a shell; wherein the thickness of the continuous alumina layer is 0.1-0.3 mm.