A high-strength and erosion-resistant lightweight dry mix and a method for preparing the same

Abstract

This invention relates to a high-strength and corrosion-resistant lightweight dry refractory and its preparation method. By weight, it comprises 32-50 parts magnesia, 44-67 parts magnesia-calcium sand, 3-5 parts a composite binder containing sugars, and 2-5 parts a composite sintering accelerator. Specifically, 7-20 parts are magnesia with a particle size of 3-5 mm, 25-30 parts are magnesia with a particle size of 1-3 mm, 29-35 parts are magnesia-calcium sand with a particle size of 0-1 mm, and 16-29 parts are magnesia-calcium sand with a particle size <0.075 mm. The purpose of this invention is to provide a high-strength and corrosion-resistant lightweight dry refractory and its preparation method. This invention addresses the technical problems of existing dry refractory materials that require expensive binders to ensure performance, leading to increased costs per ton of steel refractory, insufficient corrosion resistance, and the contamination of molten steel by small amounts of impurities such as sulfur (S) and phosphorus (P) in the dry vibrating material under the influence of high-temperature molten steel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refractory materials, in particular to a high-strength and erosion-resistant lightweight dry mix and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the national construction industry, the demand for steel continues to rise. As the last stage in continuous casting production, the performance of the tundish lining material directly affects the efficiency of continuous casting production and the cleanliness of molten steel. In the early days, traditional tundish lining used wet refractory castable or sprayed material, which needed to be combined with water, cured or baked for a long time before use. Not only does it need to be cured by baking for a long time, but it also has a long construction period, high cost and is prone to cracking and other problems.

[0003] In recent years, tundish dry mix has become an important development direction for tundish lining materials due to its advantages of easy operation and rapid baking formation. Compared with traditional castable and sprayed material, dry mix can be baked immediately after vibration, and solid-phase sintering or ceramic formation can be achieved under high temperature, which is convenient and has a short construction period. However, the existing tundish dry mix still faces the following technical problems: (1) High cost. In pursuit of high performance of tundish dry mix, high-purity raw materials or expensive binders are used in dry vibration mix, resulting in increased refractory cost per ton of steel.

[0004] (2) Transportation problem. During transportation, fluctuations in dry mix cause some large particles to separate, which cannot be remixed in the construction environment, resulting in a significant reduction in the effectiveness of tundish dry mix.

[0005] (3) Insufficient erosion resistance. Conventional dry mix is frequently subjected to surface delamination, collapse or severe erosion of the working lining due to long-term scouring by molten steel and erosion by molten slag, resulting in a shortened tundish life and affecting the production efficiency of continuous casting.

[0006] (4) Contamination of molten steel. A small amount of impurities such as S and P in dry vibration mix enter the molten steel under the scouring of high-temperature molten steel, resulting in contamination of the molten steel.

[0007] Therefore, in view of the above problems, the present application urgently needs to provide a high-strength and erosion-resistant lightweight dry mix and a preparation method thereof. SUMMARY

[0008] The purpose of this invention is to provide a high-strength and corrosion-resistant lightweight dry refractory material and its preparation method. By proposing a high-strength and corrosion-resistant lightweight dry refractory material, this invention addresses the technical problems in the prior art, such as the need to add expensive binders to ensure performance, which leads to increased cost per ton of steel refractory material, insufficient corrosion resistance, and the contamination of molten steel by small amounts of impurities such as sulfur and phosphorus contained in the dry vibrating material under the scouring of high-temperature molten steel.

[0009] The present invention provides a high-strength and corrosion-resistant lightweight dry material, which, by weight, comprises 32-50 parts of magnesia, 44-67 parts of magnesia-calcium sand, 3-5 parts of a composite binder containing sugars, and 2-5 parts of a composite accelerator. Among them, magnesia with a particle size of 3-5mm contains 7-20 parts, and magnesia with a particle size of 1-3mm contains 25-30 parts; magnesia-calcium sand contains 29-35 parts with a particle size of 0-1mm, and magnesia-calcium sand with a particle size <0.075mm contains 16-29 parts.

[0010] Preferably, the complex binder containing sugars includes glucose and silicon-containing compounds.

[0011] Preferably, the mass ratio of glucose to silicon-containing compound is (2-3):(1-2).

[0012] Preferably, the silicon-containing compound includes at least one of anhydrous sodium silicate or silica fume.

[0013] Preferably, the composite sintering accelerator includes at least one of a metal oxide or borax.

[0014] Preferably, the metal oxide includes at least one of Fe2O3 powder or TiO2.

[0015] Preferably, the magnesia has the following chemical composition: MgO 87.35wt%, CaO 2.23wt%, SiO2 5.62wt%, Al2O3 1.12wt%, Fe2O3 1.04wt%, and loss on ignition 2.64wt%.

[0016] Preferably, the magnesium calcium sand has the following chemical composition: MgO 69.35wt%, CaO 22.23wt%, SiO 25.62wt%, Al2O3 1.12wt%, Fe2O3 1.04wt%, and a loss on ignition of 0.64%.

[0017] Preferably, the median particle size of the silica fume is 0.1-0.3 μm, and the specific surface area is 15000-30000 m² / kg.

[0018] The present invention also provides a method for preparing a high-strength and corrosion-resistant lightweight dry material as described in any one of the above-mentioned methods, comprising the following steps: According to the weight proportions, pour the complex binder and complex accelerator containing sugar into the mixer and mix for 7-10 minutes to obtain the first mixture; According to the weight proportions, pour the magnesia and calcium magnesia into the mixer and mix for 5-7 minutes to obtain the second mixture; After mixing the first and second mixtures, stir again for 7-10 minutes to obtain a high-strength and corrosion-resistant lightweight dry material.

[0019] The high-strength and corrosion-resistant lightweight dry material and its preparation method provided by this invention have the following advantages compared with the prior art: 1. The method for preparing high-strength and corrosion-resistant lightweight dry aggregate provided by this invention adjusts the particle size of the magnesia, reducing the proportion of magnesia with a particle size of 3-5 mm and increasing the proportion of magnesia with a particle size of 1-3 mm. This facilitates the release of gas during the high-temperature decomposition of the binder, effectively reducing the occurrence of various accidents such as tundish separation and collapse. Simultaneously, in terms of transportation, it reduces the uneven distribution of dry aggregate caused by the segregation of large particles.

[0020] 2. The method for preparing high-strength and corrosion-resistant lightweight dry tundish provided by the present invention uses magnesia and magnesia-calcium sand in combination. Magnesia dry tundish has high corrosion resistance, good stability and long service life. Magnesia-calcium dry tundish is beneficial to purifying molten steel and improving the cleanliness of molten steel. By adding magnesia and magnesia-calcium sand at the same time, the tundish prepared with dry tundish can produce steel of higher quality.

[0021] 3. The method for preparing high-strength and corrosion-resistant lightweight dry-mixed steel provided by this invention uses a composite binder, namely glucose and silicon-containing compounds. Compared with the traditional binder phenolic resin, it does not produce harmful gases during construction, solving the problems of worker safety and environmental pollution. At the same time, the presence of glucose in the binder results in a lower linear change rate of the magnesium-calcium dry-mixed steel sample at medium and high temperatures, improving corrosion resistance and reducing accidents such as tundish drilling and tundish collapse. Furthermore, glucose decomposes at high temperatures, leaving no residue (using other substances would introduce other elements and reduce the quality of the billet). In addition, the addition of silicon-containing compounds can fill the tiny voids in the dry-mixed steel, ensuring compressive strength and corrosion resistance.

[0022] 4. The method for preparing high-strength and corrosion-resistant lightweight dry aggregate provided by this invention employs a composite accelerator, namely a mixture of metal oxide and sodium hexametasilicate. The metal oxide and silicate form low-melting-point substances during the intermediate temperature stage, thereby promoting sintering and improving the mid-term strength of the dry aggregate. When Fe2O3 powder is selected as the metal oxide, it can react with CaO in magnesia-calcium sand at 1100℃ to generate low-melting-point minerals dicalcium ferrite and aluminoferrite compounds. This not only promotes sintering of the material but also improves the mid-term compressive strength of the dry aggregate. Furthermore, the generated calcium ferrite can adhere to the surface of the raw material particles, forming a high-viscosity coating layer to resist further erosion by the slag. When TiO2 micro powder is selected as the metal oxide, TiO2 reacts with CaO to generate CaTiO3 and Ca4Ti3O3. 10 This causes lattice distortion within the material, providing energy for grain growth and thus promoting material sintering. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The present invention provides a high-strength and corrosion-resistant lightweight dry material, which, by weight, comprises 32-50 parts of magnesia, 44-67 parts of magnesia-calcium sand, 3-5 parts of a composite binder containing sugars, and 2-5 parts of a composite accelerator. Among them, magnesia with a particle size of 3-5mm contains 7-20 parts, and magnesia with a particle size of 1-3mm contains 25-30 parts; magnesia-calcium sand contains 29-35 parts with a particle size of 0-1mm, and magnesia-calcium sand with a particle size <0.075mm contains 16-29 parts.

[0025] Specifically, complex binders containing sugars include glucose and silicon-containing compounds.

[0026] Specifically, the mass ratio of glucose to silicon-containing compounds is (2-3):(1-2).

[0027] Specifically, the silicon-containing compound includes at least one of anhydrous sodium silicate or silica fume.

[0028] Specifically, the composite sintering accelerator includes at least one of a metal oxide or borax.

[0029] Specifically, the metal oxide includes at least one of Fe2O3 powder or TiO2.

[0030] Specifically, the chemical composition of the magnesia is 87.35wt% MgO, 2.23wt% CaO, 5.62wt% SiO2, 1.12wt% Al2O3, 1.04wt% Fe2O3, and 2.64wt% loss on ignition.

[0031] Specifically, the magnesia-calcium sand has the following chemical composition: MgO 69.35wt%, CaO 22.23wt%, SiO 25.62wt%, Al2O3 1.12wt%, Fe2O3 1.04wt%, and a loss on ignition of 0.64%.

[0032] Specifically, the median particle size of silica fume is 0.1-0.3 μm, and the specific surface area is 15,000-30,000 m² / kg.

[0033] The present invention also provides a method for preparing a high-strength and corrosion-resistant lightweight dry material as described in any one of the above-mentioned methods, comprising the following steps: S101) According to the weight proportions, pour the composite binder and composite accelerator containing sugar into the mixer and mix for 7-10 minutes to obtain the first mixture; S102) According to the weight parts, pour the magnesia and calcium magnesia into the mixer and mix for 5-7 minutes to obtain the second mixture; S103) After mixing the first and second mixtures, stir again for 7-10 minutes to obtain a high-strength and corrosion-resistant lightweight dry material.

[0034] The high-strength and corrosion-resistant lightweight dry aggregate provided by this invention adjusts the particle size of the magnesia, reducing the proportion of magnesia with a particle size of 3-5 mm and increasing the proportion of magnesia with a particle size of 1-3 mm. This facilitates the release of gas during the high-temperature decomposition of the binder, effectively reducing the occurrence of various accidents such as tundish separation and collapse. Simultaneously, in terms of transportation, it reduces the uneven distribution of dry aggregate caused by the segregation of large particles.

[0035] The high-strength and corrosion-resistant lightweight dry tundish provided by this invention uses a compound of magnesia and magnesia-calcium sand. Magnesia dry tundish has high corrosion resistance, good stability and long service life. Magnesia-calcium dry tundish is beneficial to purifying molten steel and improving the cleanliness of molten steel. By adding magnesia and magnesia-calcium sand at the same time, the tundish prepared with dry tundish can produce steel of higher quality.

[0036] This invention employs a composite binder, namely glucose and silicon-containing compounds. Compared with traditional binders such as phenolic resin, it does not produce harmful gases during construction, thus solving the problems of worker safety and environmental pollution. Furthermore, the presence of glucose in the binder results in a lower linear change rate in the magnesium-calcium dry aggregate samples at medium and high temperatures, improving erosion resistance and reducing accidents such as tundish drilling and collapse. At high temperatures, the glucose decomposes without residue (using other substances would introduce other elements, reducing the quality of the billet). Additionally, the addition of silicon-containing compounds fills the tiny voids in the dry aggregate, ensuring compressive strength and erosion resistance.

[0037] This invention employs a composite accelerator, namely a mixture of metal oxide and sodium hexametasilicate. The metal oxide and silicate form low-melting-point substances during the intermediate temperature stage, thereby promoting sintering and improving the mid-term strength of the dry-mixed material. When Fe2O3 powder is selected as the metal oxide, it can react with CaO in magnesia-calcium sand at 1100℃ to generate low-melting-point minerals dicalcium ferrite and aluminoferrite compounds. This not only promotes sintering but also improves the mid-term compressive strength of the dry-mixed material. Furthermore, the generated calcium ferrite can adhere to the surface of the raw material particles, forming a high-viscosity coating layer to resist further erosion by the slag. When TiO2 micro powder is selected as the metal oxide, TiO2 reacts with CaO to generate CaTiO3 and Ca4Ti3O3. 10 This causes lattice distortion within the material, providing energy for grain growth and thus promoting material sintering.

[0038] Example 1 A method for preparing a high-strength and corrosion-resistant lightweight dry-mix material includes the following steps: 101) According to the weight proportions, 5 parts of the complex binder containing sugar and 5 parts of the complex accelerator are poured into the mixer and mixed for 7 minutes to obtain the first mixture; 102) According to the weight proportions, pour 32 parts of magnesia and 58 parts of magnesia-calcium sand into a mixer and mix for 5 minutes to obtain the second mixture; 103) After mixing the first and second mixtures, stir again for 7 minutes to obtain a high-strength and corrosion-resistant lightweight dry material.

[0039] Among them, 7 parts of magnesia have a particle size of 3-5mm and 25 parts have a particle size of 1-3mm; 29 parts of calcium magnesia have a particle size of 0-1mm and 29 parts have a particle size of <0.075mm.

[0040] Complex binders containing sugars include glucose and silicon-containing compounds.

[0041] The mass ratio of glucose to silicon-containing compounds is 3:2.

[0042] Silicon-containing compounds are silica ash.

[0043] Composite sintering accelerators include metal oxides and borax.

[0044] The metal oxide is Fe2O3 powder.

[0045] The mass ratio of Fe2O3 powder to borax is 3:1.

[0046] The chemical composition of the magnesia is 87.35 wt% MgO, 2.23 wt% CaO, 5.62 wt% SiO2, 1.12 wt% Al2O3, 1.04 wt% Fe2O3, and 2.64 wt% loss on ignition.

[0047] The chemical composition of the magnesium calcium sand is MgO 69.35wt%, CaO 22.23wt%, SiO 25.62wt%, Al2O3 1.12wt%, Fe2O3 1.04wt%, with a loss on ignition of 0.64%.

[0048] The median particle size of silica fume is 0.1-0.3μm, and the specific surface area is 15000-30000㎡ / kg.

[0049] After the obtained lightweight dry material was mixed evenly, it was poured into a mold to prepare a sample block of 160 mm × 40 mm × 40 mm. The sample block was then placed in an oven at a constant temperature of 220℃ for 3 hours. After the heat treatment, the sample was cooled to room temperature to test its flexural and compressive strength. The flexural and compressive strengths were also tested at 1100℃ and 1500℃ for 3 hours. The specific material properties are shown in Table 1.

[0050] Example 2 A method for preparing a high-strength and corrosion-resistant lightweight dry-mix material includes the following steps: 201) According to the weight proportions, 4 parts of the complex binder containing sugar and 2 parts of the complex accelerator are poured into the mixer and mixed for 10 minutes to obtain the first mixture; 202) According to the weight proportions, pour 40 parts of magnesia and 51 parts of magnesia-calcium sand into a mixer and mix for 7 minutes to obtain the second mixture; 203) After mixing the first and second mixtures, stir again for 10 minutes to obtain a high-strength and corrosion-resistant lightweight dry material.

[0051] Among them, magnesia contains 10 parts of magnesia with a particle size of 3-5mm and 30 parts of magnesia with a particle size of 1-3mm; magnesia-calcium sand contains 35 parts of magnesia-calcium sand with a particle size of 0-1mm and 16 parts of magnesia-calcium sand with a particle size <0.075mm.

[0052] Complex binders containing sugars include glucose and silicon-containing compounds.

[0053] The mass ratio of glucose to silicon-containing compounds is 3:1.

[0054] Silicon-containing compounds are silica ash.

[0055] The composite sintering accelerator is a metal oxide.

[0056] The metal oxides are Fe2O3 powder and TiO2.

[0057] The mass ratio of Fe2O3 powder to TiO2 is 3:1.

[0058] The chemical composition of the magnesia is 87.35 wt% MgO, 2.23 wt% CaO, 5.62 wt% SiO2, 1.12 wt% Al2O3, 1.04 wt% Fe2O3, and 2.64 wt% loss on ignition.

[0059] The chemical composition of the magnesium calcium sand is MgO 69.35wt%, CaO 22.23wt%, SiO 25.62wt%, Al2O3 1.12wt%, Fe2O3 1.04wt%, with a loss on ignition of 0.64%.

[0060] The median particle size of silica fume is 0.1-0.3μm, and the specific surface area is 15000-30000㎡ / kg.

[0061] After the obtained lightweight dry material was mixed evenly, it was poured into a mold to prepare a sample block of 160 mm × 40 mm × 40 mm. The sample block was then placed in an oven at a constant temperature of 220℃ for 3 hours. After the heat treatment, the sample was cooled to room temperature to test its flexural and compressive strength. The flexural and compressive strengths were also tested at 1100℃ and 1500℃ for 3 hours. The specific material properties are shown in Table 1.

[0062] Example 3 A method for preparing a high-strength and corrosion-resistant lightweight dry-mix material includes the following steps: 301) According to the weight proportions, 4 parts of the complex binder containing sugar and 3 parts of the complex accelerator are poured into the mixer and mixed for 8 minutes to obtain the first mixture; 302) According to the weight proportions, pour 35 parts of magnesia and 58 parts of magnesia-calcium sand into a mixer and mix for 6 minutes to obtain the second mixture; 303) After mixing the first and second mixtures, stir again for 9 minutes to obtain a high-strength and corrosion-resistant lightweight dry material.

[0063] Among them, magnesia contains 10 parts of magnesia with a particle size of 3-5mm and 25 parts of magnesia with a particle size of 1-3mm; magnesia-calcium sand contains 35 parts of magnesia-calcium sand with a particle size of 0-1mm and 23 parts of magnesia-calcium sand with a particle size <0.075mm.

[0064] Complex binders containing sugars include glucose and silicon-containing compounds.

[0065] The mass ratio of glucose to silicon-containing compounds is 2:2.

[0066] The silicon-containing compound is anhydrous sodium silicate.

[0067] The composite sintering accelerator is a metal oxide.

[0068] Metal oxides include Fe2O3 powder and TiO2.

[0069] The mass ratio of Fe2O3 powder to TiO2 is 5:1.

[0070] The chemical composition of the magnesia is 87.35 wt% MgO, 2.23 wt% CaO, 5.62 wt% SiO2, 1.12 wt% Al2O3, 1.04 wt% Fe2O3, and 2.64 wt% loss on ignition.

[0071] The chemical composition of the magnesium calcium sand is MgO 69.35wt%, CaO 22.23wt%, SiO 25.62wt%, Al2O3 1.12wt%, Fe2O3 1.04wt%, with a loss on ignition of 0.64%.

[0072] After the obtained lightweight dry material was mixed evenly, it was poured into a mold to prepare a sample block of 160 mm × 40 mm × 40 mm. The sample block was then placed in an oven at a constant temperature of 220℃ for 3 hours. After the heat treatment, the sample was cooled to room temperature to test its flexural and compressive strength. The flexural and compressive strengths were also tested at 1100℃ and 1500℃ for 3 hours. The specific material properties are shown in Table 1.

[0073] Example 4 A method for preparing a high-strength and corrosion-resistant lightweight dry-mix material includes the following steps: 401) According to the weight ratio, 3 parts of the complex binder containing sugar and 2.5 parts of the complex accelerator are poured into the mixer and mixed for 9 minutes to obtain the first mixture; 402) According to the weight ratio, pour 40 parts of magnesia and 54.5 parts of magnesia-calcium sand into a mixer and mix for 6 minutes to obtain the second mixture; 403) After mixing the first and second mixtures, stir again for 8 minutes to obtain a high-strength and corrosion-resistant lightweight dry material.

[0074] Among them, magnesia contains 15 parts of magnesia with a particle size of 3-5mm and 25 parts of magnesia with a particle size of 1-3mm; magnesia-calcium sand contains 30 parts of magnesia-calcium sand with a particle size of 0-1mm and 24.5 parts of magnesia-calcium sand with a particle size <0.075mm.

[0075] Complex binders containing sugars include glucose and silicon-containing compounds.

[0076] The mass ratio of glucose to silicon-containing compounds is 2:1.

[0077] Silicon-containing compounds are silica ash.

[0078] Composite sintering accelerators include metal oxides and borax.

[0079] The metal oxide is Fe2O3 powder.

[0080] The mass ratio of Fe2O3 powder to borax is 4:1.

[0081] The chemical composition of the magnesia is 87.35 wt% MgO, 2.23 wt% CaO, 5.62 wt% SiO2, 1.12 wt% Al2O3, 1.04 wt% Fe2O3, and 2.64 wt% loss on ignition.

[0082] The chemical composition of the magnesium calcium sand is MgO 69.35wt%, CaO 22.23wt%, SiO 25.62wt%, Al2O3 1.12wt%, Fe2O3 1.04wt%, with a loss on ignition of 0.64%.

[0083] The median particle size of silica fume is 0.1-0.3μm, and the specific surface area is 15000-30000㎡ / kg.

[0084] After the obtained lightweight dry material was mixed evenly, it was poured into a mold to prepare a sample block of 160 mm × 40 mm × 40 mm. The sample block was then placed in an oven at a constant temperature of 220℃ for 3 hours. After the heat treatment, the sample was cooled to room temperature to test its flexural and compressive strength. The flexural and compressive strengths were also tested at 1100℃ and 1500℃ for 3 hours. The specific material properties are shown in Table 1.

[0085] Example 5 A method for preparing a high-strength and corrosion-resistant lightweight dry-mix material includes the following steps: 101) According to the weight proportions, pour 3-5 parts of the complex binder containing sugar and 2-5 parts of the complex accelerator into the mixer and mix for 7-10 minutes to obtain the first mixture; 102) According to the weight proportions, pour 50 parts of magnesia and 64 parts of magnesia-calcium sand into a mixer and mix for 5-7 minutes to obtain the second mixture; 103) After mixing the first and second mixtures, stir again for 7-10 minutes to obtain a high-strength and corrosion-resistant lightweight dry material.

[0086] Among them, magnesia contains 20 parts of magnesia with a particle size of 3-5mm and 30 parts of magnesia with a particle size of 1-3mm; magnesia-calcium sand contains 35 parts of magnesia-calcium sand with a particle size of 0-1mm and 29 parts of magnesia-calcium sand with a particle size <0.075mm.

[0087] Complex binders containing sugars include glucose and silicon-containing compounds.

[0088] The mass ratio of glucose to silicon-containing compounds is 3:1.

[0089] The silicon-containing compound is anhydrous sodium silicate.

[0090] Composite sintering accelerators include metal oxides and borax.

[0091] The metal oxide is TiO2.

[0092] The chemical composition of the magnesia is 87.35 wt% MgO, 2.23 wt% CaO, 5.62 wt% SiO2, 1.12 wt% Al2O3, 1.04 wt% Fe2O3, and 2.64 wt% loss on ignition.

[0093] The chemical composition of the magnesium calcium sand is MgO 69.35wt%, CaO 22.23wt%, SiO 25.62wt%, Al2O3 1.12wt%, Fe2O3 1.04wt%, with a loss on ignition of 0.64%.

[0094] After the obtained lightweight dry material was mixed evenly, it was poured into a mold to prepare a sample block of 160 mm × 40 mm × 40 mm. The sample block was then placed in an oven at a constant temperature of 220℃ for 3 hours. After the heat treatment, the sample was cooled to room temperature to test its flexural and compressive strength. The flexural and compressive strengths were also tested at 1100℃ and 1500℃ for 3 hours. The specific material properties are shown in Table 1.

[0095] Example 6 The only difference between this embodiment and Embodiment 1 is that the silicon-containing compounds are anhydrous sodium silicate and silica fume, and the mass ratio of anhydrous sodium silicate to silica fume is 1:1.

[0096] After the obtained lightweight dry material was mixed evenly, it was poured into a mold to prepare a sample block of 160 mm × 40 mm × 40 mm. The sample block was then placed in an oven at a constant temperature of 220℃ for 3 hours. After the heat treatment, the sample was cooled to room temperature to test its flexural and compressive strength. The flexural and compressive strengths were also tested at 1100℃ and 1500℃ for 3 hours. The specific material properties are shown in Table 1.

[0097] Example 7 The only difference between this embodiment and Embodiment 1 is that the metal oxides are Fe2O3 powder and TiO2, and the mass ratio of Fe2O3 powder to TiO2 is 3:1.

[0098] After the obtained lightweight dry material was mixed evenly, it was poured into a mold to prepare a sample block of 160 mm × 40 mm × 40 mm. The sample block was then placed in an oven at a constant temperature of 220℃ for 3 hours. After the heat treatment, the sample was cooled to room temperature to test its flexural and compressive strength. The flexural and compressive strengths were also tested at 1100℃ and 1500℃ for 3 hours. The specific material properties are shown in Table 1.

[0099] Comparative Example 1 The only difference between this comparative example and Example 1 is that the magnesia contains 20 parts of magnesia with a particle size of 3-5 mm and 20 parts of magnesia with a particle size of 1-3 mm.

[0100] After the obtained lightweight dry material was mixed evenly, it was poured into a mold to prepare a sample block of 160 mm × 40 mm × 40 mm. The sample block was then placed in an oven at a constant temperature of 220℃ for 3 hours. After the heat treatment, the sample was cooled to room temperature to test its flexural and compressive strength. The flexural and compressive strengths were also tested at 1100℃ and 1500℃ for 3 hours. The specific material properties are shown in Table 1.

[0101] Comparative Example 2 The only difference between this comparative example and Example 1 is the absence of silica ash.

[0102] After the obtained lightweight dry material was mixed evenly, it was poured into a mold to prepare a sample block of 160 mm × 40 mm × 40 mm. The sample block was then placed in an oven at a constant temperature of 220℃ for 3 hours. After the heat treatment, the sample was cooled to room temperature to test its flexural and compressive strength. The flexural and compressive strengths were also tested at 1100℃ and 1500℃ for 3 hours. The specific material properties are shown in Table 1.

[0103] Comparative Example 3 The only difference between this comparative example and Example 1 is the absence of metal oxides.

[0104] After the obtained lightweight dry material was mixed evenly, it was poured into a mold to prepare a sample block of 160 mm × 40 mm × 40 mm. The sample block was then placed in an oven at a constant temperature of 220℃ for 3 hours. After the heat treatment, the sample was cooled to room temperature to test its flexural and compressive strength. The flexural and compressive strengths were also tested at 1100℃ and 1500℃ for 3 hours. The specific material properties are shown in Table 1.

[0105] Table 1 Performance testing of lightweight dry test samples

[0106] Compared with Example 1, in Example 6, the silicon-containing compound was adjusted to a combination of anhydrous sodium silicate and silica fume in a 1:1 mass ratio in the composite binder containing sugars. Compared with Example 1, Example 6 introduced anhydrous sodium silicate as a new component. As can be seen from the data in Table 1, this adjustment improved the compressive strength of the material to a certain extent, indicating that the synergistic effect of anhydrous sodium silicate and silica fume helps to enhance the mechanical properties of the material. However, at the same time, the linear change rate at 1500℃ also increased, reflecting a decrease in the volume stability of the material, which may lead to a decrease in its corrosion resistance. This phenomenon may be attributed to: (1) the coexistence of silica fume and anhydrous sodium silicate may have changed the high-temperature reaction pathway, and the resulting phase or microstructure is more sensitive to thermal stress and chemical corrosion; (2) although the combination of the two improves the strength at medium and low temperatures, it may cause some changes in sintering behavior at high temperatures, thereby affecting corrosion resistance.

[0107] The improvement of Example 7 compared to Example 1 lies in the use of a metal oxide composite system of Fe2O3 powder and TiO2 (mass ratio 3:1). This combination has been shown to significantly enhance the compressive strength of the material at 1100℃ and 1500℃. The core mechanism is as follows: at approximately 1100℃, Fe2O3 reacts with CaO in the raw materials to form low-melting-point compounds. These molten phases, through liquid-phase diffusion mass transfer, greatly promote the sintering and densification process of the material. Simultaneously, TiO2 reacts with CaO to form products such as CaTiO3. The lattice distortion induced by this process effectively activates the crystal lattice, providing impetus for grain recrystallization and growth. It is this synergy of "liquid-phase promotion" and "solid-phase activation" that jointly ensures the strength of the material under high-temperature conditions.

[0108] Comparative data from Example 1 and Example 1 show that when the mass ratio of 3-5mm and 1-3mm magnesia sand was adjusted to be equal in Example 1, its compressive strength at 220℃, 1100℃, and 1500℃ all decreased. This fully demonstrates that the approach adopted in Example 1—optimizing particle size distribution and appropriately reducing the proportion of large-particle magnesia sand—has significant advantages. This design effectively avoids the problems of uneven mixing and structural defects easily caused by excessive coarse particles, and by improving matrix continuity, ensures that the material has more stable and superior compressive strength at various temperatures.

[0109] Comparative Example 2 and Example 1 reveal that the absence of silica fume in the binder leads to a comprehensive decrease in the material's compressive strength and erosion resistance. This result, conversely, confirms that the combined use of silica fume and glucose in Example 1 produced a positive synergistic enhancement effect: silica fume not only optimized the matrix structure through filling effect and pozzolanic reaction at medium and low temperatures, but also promoted liquid phase formation at high temperatures, thereby jointly enhancing the material's structural density and high-temperature performance, ultimately demonstrating significant advantages in both strength and erosion resistance.

[0110] Comparative Example 3, lacking the metal oxide component in its accelerator, exhibited significantly inferior compressive strength at 220°C and 1100°C, as well as erosion resistance, compared to Example 1. This comparison, from the opposite perspective, verifies the crucial role of metal oxides: their addition not only enhances the medium- and high-temperature bonding strength of the material by optimizing sintering behavior but also improves the high-temperature phase composition, thereby jointly ensuring the mechanical properties and erosion resistance of the material within its operating temperature range.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-strength and corrosion-resistant lightweight dry-mix material, characterized in that: By weight, it includes 32-50 parts of magnesia, 44-67 parts of magnesia-calcium sand, 3-5 parts of a composite binder containing sugars, and 2-5 parts of a composite accelerator. Among them, magnesia with a particle size of 3-5mm contains 7-20 parts, and magnesia with a particle size of 1-3mm contains 25-30 parts; magnesia-calcium sand contains 29-35 parts with a particle size of 0-1mm, and magnesia-calcium sand with a particle size <0.075mm contains 16-29 parts.

2. The high-strength and corrosion-resistant lightweight dry-mix material according to claim 1, characterized in that: Complex binders containing sugars include glucose and silicon-containing compounds.

3. The high-strength and corrosion-resistant lightweight dry-mix material according to claim 2, characterized in that: The mass ratio of glucose to silicon-containing compounds is (2-3):(1-2).

4. The high-strength and corrosion-resistant lightweight dry-mix material according to claim 2, characterized in that: Silicon-containing compounds include at least one of anhydrous sodium silicate or silica fume.

5. The high-strength and corrosion-resistant lightweight dry-mix material according to claim 1, characterized in that: Composite sintering accelerators include at least one of metal oxides or borax.

6. The high-strength and corrosion-resistant lightweight dry-mix material according to claim 5, characterized in that: The metal oxide includes at least one of Fe2O3 powder or TiO2.

7. The high-strength and corrosion-resistant lightweight dry-mix material according to claim 1, characterized in that: The chemical composition of the magnesia is MgO 87.35wt%, CaO 2.23wt%, SiO2 5.62wt%, Al2O3 1.12wt%, Fe2O3 1.04wt%, and loss on ignition 2.64wt%.

8. The high-strength and corrosion-resistant lightweight dry-mix material according to claim 1, characterized in that: The chemical composition of the magnesium calcium sand is MgO 69.35wt%, CaO 22.23wt%, SiO2 5.62wt%, Al2O3 1.12wt%, Fe2O3 1.04wt%, with a loss on ignition of 0.64%.

9. The high-strength and corrosion-resistant lightweight dry-mix material according to claim 4, characterized in that: The median particle size of silica fume is 0.1-0.3μm, and the specific surface area is 15000-30000㎡ / kg.

10. A method for preparing a high-strength and corrosion-resistant lightweight dry-mix material based on any one of claims 1-9, characterized in that: Includes the following steps: According to the weight proportions, pour the complex binder and complex accelerator containing sugar into the mixer and mix for 7-10 minutes to obtain the first mixture; According to the weight proportions, pour the magnesia and calcium magnesia into the mixer and mix for 5-7 minutes to obtain the second mixture; After mixing the first and second mixtures, stir again for 7-10 minutes to obtain a high-strength and corrosion-resistant lightweight dry material.

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