Preparation method of spinel-corundum-aluminate lightweight refractory

Abstract

This invention discloses a method for preparing a lightweight spinel-corundum-aluminate refractory material. First, by simulating the microstructure of sintered magnesia, a multiphase material is constructed with magnesia-alumina spinel as the main crystalline phase and calcium aluminate as the intergranular and secondary crystalline phases. This results in a spinel-calcium aluminate-calcium disaluminate multiphase material with controllable crystalline phase distribution and pore composition. Next, using this multiphase material as aggregate and corundum-spinel as the matrix, the materials are batched according to a specific particle size distribution, pressed into shape, and fired at high temperature. By introducing the spinel-calcium aluminate-calcium disaluminate multiphase material and utilizing calcium ion migration, this invention enables the preparation of a lightweight spinel-corundum-aluminate refractory material with microporous aggregate and a dense matrix. The material's load-bearing capacity at both room temperature and high temperature is not lower than (or even higher than) that of heavy refractory materials of the same material. This synergistically improves the thermal insulation, high-temperature load-bearing capacity, and resistance to media erosion of this type of lightweight refractory material.

Description

Technical Field

[0001] This invention relates to the field of refractory material production technology, and in particular to a method for preparing a spinel-corundum-aluminate lightweight refractory material. Background Technology

[0002] Spinel-corundum refractories, due to their advantages such as high operating temperature, good slag corrosion resistance, and readily available raw materials, have wide applications in thermal equipment such as ladle refining furnaces, RH refining furnaces, cement and lime calcination rotary kilns, and non-ferrous metal smelting. Currently, while focusing on refractory material consumption per ton of steel, equal emphasis is placed on energy consumption per ton of steel and green development. Therefore, energy conservation and consumption reduction in high-temperature kilns have become a major challenge for high-temperature industries. Lightweighting of refractory materials, replacing heavy refractory materials as working linings in high-temperature kilns, especially those in contact with the working medium, is expected to achieve better energy conservation and consumption reduction results.

[0003] Regarding lightweight spinel-corundum refractories, one approach is to prepare them by introducing lightweight spinel or corundum aggregates into the material. Another approach is to prepare lightweight spinel-corundum refractories with a density gradient using a magnesia carbothermic reduction-transport oxidation combined reaction sintering method. The first method, by introducing lightweight aggregates, reduces the thermal conductivity of the lightweight refractories and improves their thermal insulation properties; however, it affects the material's load softening temperature and erosion resistance because the refractory matrix is ​​not strengthened while the aggregate is lightweighted. The second method yields lightweight spinel-corundum refractories with a density gradient, ensuring both reduced thermal conductivity and good load softening temperature and erosion resistance; however, its thermal shock resistance is affected by structural limitations. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a method for preparing a spinel-corundum-aluminate lightweight refractory material, so as to prepare a refractory material that can keep the heat insulated and has good high-temperature load-bearing capacity and erosion resistance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a spinel-corundum-aluminate lightweight refractory material includes the following steps:

[0007] A one-step method was used to synthesize spinel-aluminate multiphase lightweight aggregate;

[0008] Using the aforementioned spinel-aluminate multiphase lightweight aggregate as aggregate and corundum-spinel as matrix, a spinel-corundum-aluminate lightweight refractory material is prepared. Through rational batching and controlled preparation process, and by leveraging the migration of calcium components during firing, aggregate lightweighting and matrix densification are achieved. The resulting spinel-corundum-aluminate refractory material is lightweight, and the erosion of the aggregate and matrix is ​​balanced during use. This results in a synergistic improvement in thermal insulation, high-temperature load-bearing capacity, and resistance to working medium erosion.

[0009] In one embodiment, regarding the Al2O3-MgO-CaO ternary system, during the batching process, the present invention simulates the microstructure of sintered magnesia to regulate the aggregate composition and microstructure, constructing a multiphase material with magnesium aluminum spinel as the main crystalline phase and calcium aluminate as the intercrystalline and secondary crystalline phase microstructure. By adjusting the proportions of CaO, MgO, and Al2O3 components in the batching, the microstructure and phase composition of the spinel-aluminate multiphase lightweight aggregate are regulated, and the densification degree of the lightweight multiphase aggregate is regulated by adjusting the firing regime.

[0010] In one embodiment, the one-step synthesis of spinel-aluminate multiphase lightweight aggregate comprises the following steps:

[0011] Step 11: Take the calcium source, magnesium source, and aluminum source, mix and ball-mill them, and dry them for later use. For example, by weight, the ratio of the calcium source, magnesium source, and aluminum source is (2-8):(26-36):(62-72). The magnesium source can be derived from magnesium hydroxide, magnesite, magnesia, or dolomite; the calcium source can be derived from calcium carbonate or dolomite; the aluminum source can be derived from tabular corundum fine powder, industrial alumina fine powder, or activated alumina micro powder; and the magnesia can be sintered magnesia or fused magnesia.

[0012] Step 12: Mix the mixture obtained in step 11 with the binder.

[0013] Step 13: Press the material after step 12 into shape and perform time gradient drying;

[0014] Step 14: After the dried material is calcined, cooled, crushed, and sieved, the multiphase lightweight aggregate is obtained.

[0015] In one embodiment, the drying conditions in step 11 are: drying at 105-110℃ for 8-12 hours; in step 12, the binder is pulp waste liquor, and the amount of pulp waste liquor added is 4-6% of the weight of the mixture obtained in step 11, and the mixture is allowed to rest for 12-24 hours; in step 13, the mixture is first naturally dried for 8-12 hours, and then subjected to time gradient drying, which is: drying at 30℃, 60℃, and 90℃ for 3 hours respectively, and then drying at 105-110℃ for 8-12 hours; the firing conditions in step 14 are: 1700-1750℃ for 3-6 hours. The final aggregate has an apparent porosity of 20.0-35.0%, a closed porosity of 2.0-5.0%, and a bulk density of 2.40-2.65 g / cm³. 3 The true density is 3.30–3.60 g / cm³. 3 The water absorption rate is 5.0%–15.0%.

[0016] In one embodiment, using the spinel-aluminate multiphase lightweight aggregate as aggregate and corundum-spinel as matrix, a spinel-corundum-aluminate lightweight refractory material is prepared by the following method:

[0017] Step 21: Mix and grind corundum and spinel evenly to obtain fine matrix powder. For example, use tabular corundum powder, alumina powder, and magnesia powder as matrix raw materials, grind them to below 180 mesh, calculate the required mass of each matrix raw material according to the chemical formula of MgAl2O4 using alumina powder and magnesia powder, and mix them evenly according to the mass ratio of corundum to spinel of 75:25 to obtain the matrix portion in the refractory material.

[0018] Step 22: The refractory material raw materials are batched according to a certain particle size distribution, wherein the coarse aggregate is the spinel-aluminate multiphase lightweight aggregate, and the fine aggregate is the spinel-aluminate multiphase lightweight aggregate, corundum particles, or magnesia.

[0019] Step 23: Add coarse and fine aggregates, binder, and matrix in sequence, mix, and then place in a sealed container or plastic bag to rest. For example, first add coarse and fine aggregates and mix for 2-5 minutes, then add binder and mix for 3-5 minutes, and finally add matrix powder and mix for 5-20 minutes. After mixing, place in a sealed container or plastic bag to rest for 2-6 hours to allow the binder to distribute more evenly and facilitate molding. For example, by weight, the ratio of aggregate to matrix powder is between (60-70):(30-50), the binder is pulp waste liquid, and the resting time is 2-6 hours.

[0020] Step 24: The material after drying is semi-dry molded to obtain a green sample. For example, a hydraulic press is used to press the material into a green body of a certain shape and size. According to the size of the brick blank, different types of molds and appropriate pressure are selected to press the green sample into a green sample of a certain size.

[0021] Step 25: The green sample is naturally air-dried for half a day to one day, and then dried in a drying equipment, preferably by means of staged heating and heat preservation, and finally kept at 110°C for 12 to 24 hours.

[0022] Step 26: After heat preservation, the sample is kept at 1600℃~1700℃ for 3h~6h to obtain the lightweight refractory material. For example, the sample firing is carried out in a high-temperature furnace. First, the samples are neatly placed in the furnace chamber, then the furnace heating program is set, and the furnace body is heated to 1600℃~1700℃. Once this temperature range is reached, heat preservation is carried out for 3h~6h. The furnace heating rate is controlled to ensure that the chemical components in each sample react fully. The sample is fired through reaction to obtain a lightweight refractory material with low bulk density and high strength.

[0023] Compared with the prior art, the beneficial effects of the present invention are: while providing thermal insulation, it has high-temperature load-bearing capacity and corrosion resistance comparable to heavy refractory materials, and also has a certain purification effect on molten steel. Attached Figure Description

[0024] Figure 1 The images show the XRD patterns of samples MA-87, MA-90, and MA-95 in the embodiments of the present invention.

[0025] Figure 2 The image shown is a SEM image of the MA-87 sample in this embodiment of the invention after being kept at 1750℃ for 3 hours, where (b) is an enlarged view of (a).

[0026] Figure 3 for Figure 2 The corresponding surface scan energy spectrum.

[0027] Figure 4 This is a SEM image of the MA-90 sample in this embodiment of the invention after being kept at 1750℃ for 3 hours, where (e) is an enlarged view of (d).

[0028] Figure 5 for Figure 4 The corresponding surface scan energy spectrum.

[0029] Figure 6 This is a SEM image of the MA-95 sample in this embodiment of the invention, which was kept at 1750℃ for 3 hours, where (h) is an enlarged view of (g).

[0030] Figure 7 for Figure 6 The corresponding surface scan energy spectrum.

[0031] Figure 8 The images show the phase composition (a) and microstructure (b) of the sample from Example 1.

[0032] Figure 9 The images show the phase composition (a) and microstructure (b) of the sample from Example 2.

[0033] Figure 10 The images show the phase composition (a) and microstructure (b) of the sample from Example 3.

[0034] Figure 11 The images show the phase composition (a) and microstructure (b) of the sample from Example 4. Detailed Implementation

[0035] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0036] This invention first prepares a spinel-aluminate multiphase lightweight aggregate, and then prepares a spinel-corundum-aluminate lightweight refractory material based on this aggregate. This lightweight refractory material improves its high-temperature performance while maintaining low thermal conductivity. The refractory material preparation method is as follows:

[0037] A one-step method was used to synthesize spinel-aluminate multiphase lightweight aggregate;

[0038] Using the spinel-aluminate multiphase lightweight aggregate as aggregate and corundum-spinel as matrix, a spinel-corundum-aluminate lightweight refractory material was prepared.

[0039] Specifically, platy corundum powder and in-situ generated magnesium aluminum spinel were selected as the matrix, and synthesized spinel-aluminate multiphase lightweight aggregate was used as the aggregate. The aggregate was then proportioned according to a specific particle size distribution and pressed into shape using a hydraulic press. The shaped samples were dried in a drying oven and finally placed in a high-temperature sintering furnace, heated to 1650–1750℃ and held for 3–9 hours to sinter. Specifically, the spinel was magnesium aluminum spinel, and the aluminate was calcium aluminate. Around the Al2O3-MgO-CaO ternary system, by simulating the microstructure of magnesia, a multiphase material with magnesium aluminum spinel as the main crystalline phase and calcium aluminate as the intercrystalline and secondary crystalline phases was constructed, resulting in a MA (spinel)-CA (calcium aluminate)-CA2 (dialuminate) multiphase material with controllable crystalline phase distribution and pore composition. This multiphase material's spinel phase can absorb elements such as iron and manganese from slag at high temperatures, while the intergranular phase (calcium aluminate-dialuminate) can densify the matrix and microporosity of the aggregate through calcium component migration during the material's firing process. Under operating conditions, it can form low-melting-point aluminates, promoting the removal of oxide inclusions in steel and achieving the purpose of purifying molten steel. By adjusting the proportions of CaO, MgO, and Al2O3 components in the feedstock, the microstructure and phase composition of the spinel-aluminate multiphase lightweight aggregate can be controlled, and the degree of densification of the lightweight multiphase aggregate can be controlled by adjusting the firing regime. Furthermore, by introducing MA-CA-CA2 multiphase material and utilizing calcium ion migration, a spinel-corundum-aluminate lightweight refractory material with microporous aggregate and dense matrix can be prepared. While ensuring that the aggregate is appropriately weakened, the matrix is ​​strengthened, the overall corrosion of the material is balanced, and the load-bearing capacity of the material at room temperature and high temperature is not lower than (or even higher than) that of heavy refractory materials of the same material. This results in a synergistic improvement in the thermal insulation, high temperature load-bearing capacity and resistance to media erosion performance of this type of lightweight refractory material, thereby improving its comprehensive performance.

[0040] The preparation process of the above-mentioned spinel-corundum-aluminate lightweight refractory material can be further described in detail as follows:

[0041] Step 1, a one-step high-temperature reaction synthesis of spinel-aluminate lightweight aggregate, includes the following preparation process:

[0042] a. Abrasive: Grind calcium source (such as calcium carbonate), magnesium source (such as magnesium hydroxide), and aluminum source (such as alumina) using a ball mill until the passing rate of a 180-mesh sieve is higher than 90%.

[0043] b. Ingredients: Preferably, the ratio of the calcium source, magnesium source, and aluminum source by weight is (2-8):(26-36):(62-72). The present invention provides spinel-aluminate lightweight aggregate ingredients with three typical phase compositions as shown in Table 1.

[0044] Table 1. Proportion of MgAl2O4-CaAl2O4-Ca2Al4O7 multiphase raw materials with different spinel contents (wt%)

[0045] Experimental protocol <![CDATA[CaCO3]]> <![CDATA[Mg(OH)2]]> <![CDATA[α-Al2O3]]> Total (excluding mass lost due to burn-off) MA-87 7.07 33.38 71.70 100 MA-90 5.43 36.63 72.10 100 MA-95 2.69 36.73 71.86 100

[0046] In the table, MA-87, MA-90, and MA-95 refer to spinel contents of 87%, 90%, and 95% respectively during the preparation. The contents of CaCO3+Mg(OH)2+α-Al2O3 in each experimental scheme are greater than 100%, which is due to the inclusion of loss on ignition, i.e., the decomposition of CaCO3 and Mg(OH)2 at high temperatures releases carbon dioxide and water respectively.

[0047] c. Mixing: Weigh the raw materials according to the different raw material ratios above. The mass ratio of the mixture to the ball milling media is 1:2. Dry mix at 300 r / min for 3 hours to obtain a uniform powder with high surface energy. After mixing, put it into an oven and dry it at 105-110℃ for 8-12 hours, preferably at 110℃ for 12 hours.

[0048] d. Add 4-6 wt% of pulp waste liquor as a binder to the mixture, mix evenly, and let it rest for 12-24 hours, preferably 24 hours.

[0049] e. Molding: The above-mentioned material is pressed into shape using a hydraulic press. The sample was molded under a pressure of 150 MPa.

[0050] f. Drying: Place the formed blank at room temperature and allow it to dry naturally for 8–12 hours, preferably 12 hours. Then place it in a drying oven and dry it using a time gradient. Dry it at 30℃, 60℃, and 90℃ for 3 hours each, and then at 105–110℃ for 8–12 hours, preferably at 110℃ for 12 hours.

[0051] g. Firing: The sample is fired in a high-temperature furnace at 1700-1750℃ for 3-6 hours, preferably at 1750℃ for 3 hours. After firing is completed and the sample is cooled with the furnace temperature, it is taken out.

[0052] h. Performance characterization: The aggregate obtained by this invention has an apparent porosity of 20.0–35.0%, a closed porosity of 2.0–5.0%, and a bulk density of 2.40–2.65 g / cm³. 3 The true density is 3.30–3.60 g / cm³. 3 The water absorption rate is 5.0–15.0%. For example, the basic properties of three spinel-aluminate multiphase refractories with different contents are shown in Table 2; the phase composition and microstructure photographs of the samples are shown below. Figures 1 to 7 As shown. Among them. Figure 1 The XRD patterns of MA-87, MA-90, and MA-95 samples are shown. Figure 2 and Figure 3 The microstructure of the MA-87 sample is shown. Figure 4 and Figure 5 The microstructure of the MA-90 sample is shown. Figure 6 and Figure 7 The microstructure of the MA-90 sample is shown.

[0053] Table 2. Properties of three spinel-aluminate composite materials with different contents.

[0054] Multiphase materials Apparent porosity / % Porosity / % <![CDATA[Volume density / g / cm 3 > <![CDATA[True density / g / cm 3 > Water absorption rate / % MA-87 22.64 1.91 2.49 3.30 9.10 MA-90 24.03 1.98 2.56 3.46 9.40 MA-95 32.98 2.02 2.34 3.60 14.10

[0055] I. Crushing: The calcined sample is crushed by a jaw crusher and screened into particles of 3-1mm, 1-0.088mm and fine powder smaller than 0.088mm for later use.

[0056] Step two: Using spinel-aluminate multiphase lightweight aggregate as aggregate and corundum-spinel as matrix, prepare spinel-corundum-aluminate lightweight refractory material, as follows:

[0057] a. Select platy corundum fine powder, alumina micro powder, and magnesia fine powder as the matrix raw materials in the spinel-corundum-aluminate refractory material. Grind the raw materials to 180 mesh or below. First, calculate the required mass of each raw material according to the chemical formula of MgAl2O4 using alumina micro powder and magnesia fine powder. Preferably, mix them evenly at a corundum to spinel mass ratio of 75:25 as the matrix component in the refractory material. To improve the uniformity and stability of product quality, the fine powder component is best mixed for 30 to 90 minutes to ensure uniform mixing of all components.

[0058] b. The refractory raw materials are batched according to a certain particle size distribution. The aggregate can be a synthetic spinel-aluminate multiphase material with different spinel contents, corundum particles, or magnesia particles. The spinel-aluminate multiphase material is used as coarse aggregate, while the fine aggregate can be selected from the three.

[0059] c. First, add coarse and fine aggregates and mix for 2-5 minutes, then add pulp waste liquor and mix for 3-5 minutes, followed by matrix fine powder and mixing for 5-20 minutes. After mixing, place the mixture in a sealed container or plastic bag and let it sit for 2-6 hours to allow the binder to distribute more evenly and facilitate molding. By weight, the general ratio of aggregate to matrix is ​​between 60-70:30-50.

[0060] d. The mixed materials are molded using a semi-dry method and pressed into blanks of a certain shape and size using a hydraulic press. Depending on the size of the brick blank, different types of molds and appropriate pressures are selected to press into green samples of a certain size.

[0061] e. Allow the molded sample to air dry naturally for half a day to one day, then dry it in a drying equipment using a phased heating and heat preservation method, and finally keep it at 110℃ for 12 to 24 hours.

[0062] f. The sample firing is carried out in a high-temperature furnace. First, the samples are placed in the furnace chamber in sequence and then the furnace heating program is set to heat the furnace body to 1600℃~1700℃. Once the temperature reaches this range, it can be held for 3h~6h. The furnace heating rate is controlled to ensure that the chemical components in each sample react fully. The sample is fired through reaction to obtain a lightweight refractory material with low bulk density and high strength.

[0063] In the spinel-aluminate lightweight aggregate raw material, the magnesium source can be derived from magnesium hydroxide, magnesite, magnesia, or dolomite; the calcium source can be derived from calcium carbonate or dolomite; the aluminum source can be derived from tabular corundum fine powder, industrial alumina fine powder, or activated alumina micro powder; and the magnesia is sintered magnesia or fused magnesia.

[0064] The advantages of the spinel-corundum-aluminate lightweight refractory material prepared by the present invention are mainly reflected in the following aspects:

[0065] (1) By introducing artificially synthesized MA (spinel)-CA (calcium aluminate)-CA2 (calcium dialuminate) multiphase material, and by taking advantage of the migration of calcium components, a lightweight spinel-corundum-aluminate refractory material with microporous aggregate and dense matrix is ​​prepared. This allows the lightweight refractory material to be appropriately weakened in aggregate while the matrix is ​​strengthened, and the overall corrosion of the material is balanced, so that the thermal insulation, high temperature load-bearing and resistance to working medium erosion are synergistically improved.

[0066] (2) Spinel-corundum-aluminate lightweight refractories inherit the advantages of spinel-corundum refractories, such as high service temperature, good slag corrosion resistance, and readily available raw materials. While providing thermal insulation, they also have the high-temperature load-bearing capacity and corrosion resistance of heavy refractories, and have a certain purification effect on molten steel.

[0067] The spinel-corundum-aluminate lightweight refractory material prepared by this invention has the characteristics of low bulk density and high load-bearing capacity at room temperature and high temperature. It is expected to have good resistance to media erosion while ensuring thermal insulation performance.

[0068] The following are the preferred embodiments of the present invention provided by the inventors. The present invention is not limited to these embodiments. The applicant's experiments have proven that, within the scope given by the present invention, lightweight spinel-corundum-aluminate refractory materials with excellent properties can be prepared.

[0069] Example 1:

[0070] Using 180-mesh tabular corundum powder and 180-mesh magnesia powder as raw materials, the lightweight refractory matrix was batched and ball-milled at a mass ratio of corundum:spine = 75:25. Multiphase material particles with 87% spinel content (3–1 mm and 1–0.088 mm, respectively) (MA-87 in Table 2) were used as coarse and medium particles. The aforementioned corundum-spinel co-milled powder was used as the matrix fine powder. The ratio of coarse particles (3–1 mm): medium particles (1–0.088 mm): fine powder (<180 mesh) was 40:20:40. Using waste pulp liquor as a binder at a dosage of 6-8 wt%, the ingredients were thoroughly mixed and then molded on a hydraulic press. The molding pressure was adjusted according to the sample size. The samples underwent staged heating and drying, followed by firing in a high-temperature furnace. The dried samples were placed in the furnace, the heating program was set, and the temperature was raised to 1700℃ and held for 3 hours to obtain a spinel-corundum-aluminate lightweight refractory material. The properties of the samples are shown in Table 3. The phase composition and microstructure photographs of the samples are shown below. Figure 8 .

[0071] Table 3 shows the properties of the spinel-corundum-aluminate lightweight refractory material corresponding to Example 1.

[0072]

[0073] Example 2:

[0074] Using 180-mesh tabular corundum powder and 180-mesh magnesia powder as raw materials, the lightweight refractory matrix was prepared by batching and ball milling at a mass ratio of corundum:spine = 75:25. Multiphase material particles (MA-90 in Table 2) with a spinel content of 90% and a size of 3–1 mm and 1–0.088 mm were used as coarse and medium particles, respectively. The aforementioned corundum-spinel co-ground powder was used as the matrix fine powder. The ratio of coarse particles:medium particles:fine powder was 40:20:40. Waste pulp was used as a binder at a dosage of 6-8%. After thorough mixing, the mixture was formed on a hydraulic press, with the forming pressure adjusted according to the sample size. The samples were dried in stages and then fired in a high-temperature furnace. The dried samples were placed in the furnace, the heating program was set, and the temperature was raised to 1700℃ and held for 3 hours to obtain the spinel-corundum-aluminate lightweight refractory. The sample properties are shown in Table 4. The phase composition and microstructure of the sample are shown in the following images. Figure 9 .

[0075] Table 4 shows the properties of the spinel-corundum-aluminate lightweight refractory material corresponding to Example 2.

[0076]

[0077] Example 3:

[0078] Using 180-mesh tabular corundum powder and 180-mesh magnesia powder as raw materials, the lightweight refractory matrix was prepared by batching and ball milling at a mass ratio of corundum:spine = 75:25. Multiphase material particles with 95% spinel content (3–1 mm and 1–0.088 mm, respectively) (MA-95 in Table 2) were used as coarse and medium particles. The aforementioned corundum-spinel co-ground powder was used as the matrix fine powder. The ratio of coarse particles:medium particles:fine powder was 40:20:40. Waste pulp was used as a binder at a dosage of 6-8%. After thorough mixing, the mixture was formed on a hydraulic press, with the forming pressure adjusted according to the sample size. The samples were dried in stages and then fired in a high-temperature furnace. The dried samples were placed in the furnace, the heating program was set, and the temperature was raised to 1700℃ and held for 3 hours to obtain the spinel-corundum-aluminate lightweight refractory. The sample properties are shown in Table 5. The phase composition and microstructure of the sample are shown in the following images. Figure 10 .

[0079] Table 5 shows the properties of the spinel-corundum-aluminate lightweight refractory material corresponding to Example 3.

[0080]

[0081] Example 4:

[0082] Using 180-mesh tabular corundum powder and 180-mesh magnesia powder as raw materials, the lightweight refractory matrix was prepared by batching and ball milling at a mass ratio of corundum:spine = 75:25. Coarse particles (MA-95 in Table 2) with a 3-1 mm diameter and 95% spinel content were used, along with medium particles (1-0.088 mm tabular corundum). The co-ground corundum-spinel powder was used as the matrix fine powder. The ratio of coarse particles:medium particles:fine powder was 40:20:40. Waste pulp was used as a binder at a concentration of 6-8%. After thorough mixing, the mixture was formed on a hydraulic press, with the forming pressure adjusted according to the sample size. The samples were dried in stages and then fired in a high-temperature furnace. The dried samples were placed in the furnace, the heating program was set, and the temperature was raised to 1700℃ and held for 3 hours to obtain the spinel-corundum-aluminate lightweight refractory. The properties of the samples are shown in Table 6, and the phase composition and microstructure photographs of the samples are shown below. Figure 11 .

[0083] Table 6 shows the properties of the spinel-corundum-aluminate lightweight refractory material corresponding to Example 4.

[0084]

[0085] In summary, the spinel-corundum-aluminate lightweight refractory material of this invention has a room temperature and high temperature load-bearing capacity that is no less than (or even higher than) that of heavy refractory materials of the same material, and its thermal insulation, high temperature load-bearing capacity and resistance to media erosion are synergistically improved.

Claims

1. A method for preparing a spinel-corundum-aluminate lightweight refractory material, characterized in that, Includes the following steps: The following steps describe the one-step synthesis of spinel-aluminate multiphase lightweight aggregate: Step 11: Take calcium source, magnesium source and aluminum source, mix and ball mill, dry and set aside. The ratio of calcium source, magnesium source and aluminum source by weight is (2~8):(26~36):(62~72). Step 12: Mix the mixture obtained in step 11 with the binder and then bind the mixture. Step 13: Press the material after being trapped in step 12 into shape and perform time gradient drying; Step 14: After the dried material is fired, cooled, crushed, and sieved, the multiphase lightweight aggregate is obtained. The firing conditions are 1700~1750℃ for 3h~6h. The resulting aggregate has an apparent porosity of 20.0~35.0%, a closed porosity of 2.0~5.0%, and a bulk density of 2.40~2.65g / cm³. 3 The true density is 3.30~3.60 g / cm³. 3 The water absorption rate is 5.0~15.0%; Using the aforementioned spinel-aluminate multiphase lightweight aggregate as aggregate and corundum-spinel as matrix, a spinel-corundum-aluminate lightweight refractory material is prepared by the following method: Step 21: Mix and grind corundum and spinel together to make fine matrix powder; Step 22: The refractory material raw materials are batched according to a certain particle size distribution, wherein the coarse aggregate is the spinel-aluminate multiphase lightweight aggregate and the fine aggregate is the spinel-aluminate multiphase lightweight aggregate. Step 23: Add coarse and fine aggregates, binder and matrix powder in sequence, mix and place in a sealed container or plastic bag for storage. By weight, the ratio of aggregate to matrix powder is between (60~70): (30~50). Step 24: The material after being trapped is semi-dry molded to obtain a green sample; Step 25: The green sample is naturally air-dried for half a day to one day, then dried in a drying device, and finally kept at 110°C for 12 to 24 hours. Step 26: After heat preservation, the sample is kept at 1700℃ for 3h~6h to obtain the lightweight refractory material.

2. The method for preparing the spinel-corundum-aluminate lightweight refractory material according to claim 1, characterized in that, In step 11, the mixture is dried at 105-110℃ for 8-12 hours. In step 12, the binder is pulp waste liquor, and the amount of pulp waste liquor added is 4-6% of the weight of the mixture obtained in step 11. The mixture is then allowed to stand for 12-24 hours.

3. The method for preparing the spinel-corundum-aluminate lightweight refractory material according to claim 1, characterized in that, In step 13, the product is first naturally dried for 8-12 hours, and then subjected to time gradient drying, which involves drying at 30℃, 60℃, and 90℃ for 3 hours, and then drying at 105-110℃ for 8-12 hours.

4. The method for preparing the spinel-corundum-aluminate lightweight refractory material according to claim 1, characterized in that, In step 23, the binder is pulp waste liquor, and the material is cured for 2-6 hours.

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