Salt penetration erosion resistant refractory product and preparation method and application thereof

Abstract

The invention relates to the technical field of refractory materials, in particular to a salt penetration corrosion resistant refractory product as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing a chromium zirconium corundum brick with sol in a vacuum state under a stirring condition, heating, then carrying out pressurization treatment, and drying after pressure relief; the sol is selected from one or more of silica sol, aluminum sol and aluminum sulfate sol. According to the invention, the apparent porosity can be obviously reduced, the volume density can be increased, the compression strength and the erosion resistance can be enhanced, the service life of the chromium-zirconium corundum brick for hazardous waste can be greatly prolonged, and the problems of easy freezing, layering, nonuniformity and the like of sol can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory materials, and in particular to a refractory product resistant to salt penetration and corrosion, and a preparation method and application thereof. Background Art

[0002] Improper handling of hazardous waste can cause serious environmental pollution problems. With increasingly stringent environmental protection requirements, the hazardous waste industry has made rapid progress in classified collection, resource recovery, and harmless disposal, especially incineration disposal technology and related industries have developed rapidly. Currently, high-temperature incineration is one of the most effective ways to safely dispose of and reduce the volume of hazardous waste, but it also faces problems in process technology innovation, operational level improvement, and refractory material selection and maintenance. Refractory materials are indispensable key consumables for incineration systems. Due to the wide variety of hazardous wastes, complex composition, and serious regional differences, a typical hazardous waste disposal process refractory material design and selection system has not yet been established. In addition, improper selection of refractory materials can easily lead to abnormal shutdown accidents of hazardous waste incinerators, seriously affecting the long-term stable operation of hazardous waste incinerators.

[0003] Hazardous waste primarily contains chemicals such as Cl, S, P, halogens, inorganic salts, and fluorine, while also treating waste gas and wastewater, resulting in complex material characteristics. Hazardous waste rotary kilns typically operate at temperatures of 1050°C, with high-temperature zones exceeding 1350°C. The complex chemical reactions during treatment can severely erode refractory materials. Furthermore, materials from different regions and sources vary significantly in their physical properties, calorific value, and composition. Therefore, refractory materials must possess: 1) high strength and good wear resistance to withstand abrasion from solid materials, especially iron; 2) good volume stability and corrosion resistance to withstand corrosion from acidic materials within the furnace; 3) good thermal shock resistance to resist damage from furnace temperature fluctuations; and 4) good high-temperature corrosion resistance to withstand corrosion from high-salt materials, especially fluorine-containing slag.

[0004] Chrome-zirconium corundum bricks typically use fused corundum, chromium oxide, and zirconium oxide as their primary raw materials. They were developed primarily to address the harsh thermal environment and waste solution damage mechanisms within hazardous waste rotary kilns. However, in recent years, severe overcapacity in the hazardous waste industry has led to significant changes in hazardous waste collection and storage structures, resulting in material incompatibility. During incineration, the salt content of the materials is generally above 10%. Traditional chrome-zirconium corundum bricks have a high apparent porosity, making them susceptible to penetration and erosion by direct contact with molten slag and kiln-injected waste liquids. This can lead to flaking and damage of the refractory bricks, and frequent furnace shutdowns and maintenance are detrimental to actual production. Furthermore, the current impregnation method commonly used in the refractory industry involves drying the fired refractory bricks in a vacuum chamber, where they are then impregnated with a sol under vacuum. However, in actual production, this results in low production efficiency and poor product performance. Furthermore, in winter, due to the low temperatures, the sol easily freezes and stratifies, limiting production efficiency, product performance, and stability. Summary of the Invention

[0005] To address the above technical issues, the present invention provides a salt-penetration-resistant refractory product and a method for its preparation. By optimizing the sol and innovatively employing a vacuum-assisted, pressurized process, the present invention significantly accelerates impregnation efficiency. Furthermore, through constant heating and stirring, the impregnation sol maintains stable performance and uniform composition, addressing the impact of cold weather on production. The preparation method provided by the present invention can effectively enhance the overall performance of refractory products.

[0006] In a first aspect, the present invention provides a method for preparing salt-penetration-resistant refractory products, comprising: mixing chromium-zirconium corundum bricks with a sol under vacuum and stirring conditions, heating the mixture, then pressurizing the mixture, and drying the mixture after depressurization; the sol being selected from one or more of silica sol, alumina sol, and aluminum sulfate sol. In this method, by impregnating chromium-zirconium corundum bricks fired at high temperatures in a tunnel kiln with the sol under vacuum, stirring the mixture, and then pressurizing the mixture, followed by depressurization and drying, the salt-penetration-resistant refractory products can significantly reduce apparent porosity, increase bulk density, and enhance compressive strength, significantly improving the service life of chromium-zirconium corundum bricks used for hazardous waste. Furthermore, during the kiln heating process, the sol readily forms active silicon oxide and aluminum oxide components. During high-temperature use, these components react with components of the chromium-zirconium corundum bricks (including particles and matrix) to form mullite, accompanied by volume expansion, further reducing porosity. They also form a solid solution with chromium oxide, further enhancing the material's corrosion resistance and temperature resistance.

[0007] Preferably, the sol is selected from at least two of silica sol, alumina sol, and aluminum sulfate sol, preferably silica sol and alumina sol, and the mass ratio of the silica sol to the alumina sol is 3:1 to 1:1, for example, 3:1, 2:1, 1.5:1, 1:1, etc.

[0008] Preferably, the mass fraction of SiO2 in the silica sol is 10% to 40%, such as 10%, 20%, 30%, 40%, etc., and is preferably 20%.

[0009] Preferably, the mass fraction of Al2O3 in the aluminum sol is 20% to 25%, such as 20%, 22%, 23%, 24%, 25%, etc., and is preferably 20%.

[0010] Preferably, the mass fraction of aluminum sulfate in the aluminum sulfate sol is 20% to 40%, for example, 20%, 30%, 40%, etc.

[0011] The present invention can significantly improve various properties of the product, such as bulk density, strength, and slag erosion resistance, by optimizing the process and adopting specific sol treatment.

[0012] Further preferably, the chrome-zirconium corundum brick is a chrome-zirconium corundum brick fired at high temperature in a tunnel kiln; preferably, in the chrome-zirconium corundum brick, the mass fraction of Al2O3 is 80%~90%, the mass fraction of Cr2O3 is 3%~15%, and the mass fraction of ZrO2 is 2%~10%.

[0013] More preferably, the vacuum degree of the vacuum state is 2500~3000Pa.

[0014] More preferably, the pressure of the pressurization treatment is 1-1.4 MPa, and the pressurization time is 15-25 min.

[0015] In the present invention, by adopting the above-mentioned preferred preparation method and conditions, the preparation efficiency can be accelerated while significantly enhancing the sol impregnation effect, so that the comprehensive performance of the salt penetration erosion resistant refractory products, such as apparent porosity, bulk density, compressive strength and slag erosion resistance, is better.

[0016] Preferably, the heating temperature is above 15°C, preferably 15-50°C.

[0017] Preferably, the stirring speed is 100-400 r / min, and the number of the stirring devices is 2-6. In the present invention, by stirring and using 2-6 stirring devices, the sol is kept in a stirred and homogenized state when in working state.

[0018] According to a preferred embodiment of the present invention, based on the preparation method and sol of the present invention, by first vacuuming to 2500~3000Pa and then pressurizing 1~1.4MPa, the preparation efficiency is accelerated, the sol impregnation effect is further enhanced, and the overall performance of the product is significantly improved. In addition, by heating and constant temperature and stirring, the working temperature is maintained above 15°C, which can overcome the impact of severe winter weather on the preparation, reduce the viscosity of the sol, and enhance the impregnation effect. At the same time, the sol is kept in a stirred state, and the sol maintains homogenization during operation, solves the problem of sol stratification, and accelerates the sol impregnation efficiency, resulting in a more stable product performance.

[0019] Preferably, the drying temperature is 105-115° C. and the drying time is 20-30 h.

[0020] In a second aspect, the present invention provides a refractory product resistant to salt penetration and corrosion, which is prepared by the above-mentioned preparation method.

[0021] Preferably, the salt penetration erosion resistant refractory product has an apparent porosity of 5.1% to 6.9% and a bulk density of 3.30 to 3.42 g / cm 3 , the compressive strength is 127~140MPa, and the permeability area percentage is 7%~17%.

[0022] In a third aspect, the present invention provides applications of the aforementioned preparation method or salt-penetration-resistant refractory product, particularly in refractory materials for hazardous waste incineration equipment, waste gas and waste liquid incineration equipment, or domestic waste incineration equipment. The present invention can extend the service life of refractory materials for hazardous waste incineration equipment with high salt content.

[0023] The present invention has at least one beneficial effect: the preparation method provided by the present invention enables better bonding between the chromium-zirconium corundum brick and the sol, significantly reducing apparent porosity, increasing bulk density, enhancing compressive strength and corrosion resistance, and significantly extending the service life of the chromium-zirconium corundum brick for hazardous waste. Furthermore, the vacuum-assisted, pressurized preparation method, combined with constant temperature heating and stirring, mitigates the impact of freezing of the sol in cold winter weather on the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 These are the remaining chromium-zirconium corundum bricks after use in the hazardous waste incinerator in the embodiment of the present invention.

[0026] Figure 2 Schematic diagram of the overall impregnation equipment in an embodiment of the present invention.

[0027] Figure 3 This is the SEM image of an ordinary chromium-zirconium corundum brick provided in Comparative Example 1 of the present invention, which was fired in a high-temperature tunnel kiln but not impregnated with vacuum sol.

[0028] Figure 4 This is the SEM image of slag corrosion of ordinary chromium-zirconium corundum bricks provided in Comparative Example 1 of the present invention after being fired in a high-temperature tunnel kiln but not impregnated with vacuum sol.

[0029] Figure 5 This is the SEM image of slag corrosion in Example 1 of the present invention.

[0030] Figure 6 This is the SEM image of slag corrosion in Example 2 of the present invention.

[0031] Figure 7 This is the SEM image of slag corrosion in Example 3 of the present invention.

[0032] Figure 8 This is the SEM image of slag corrosion in Example 4 of the present invention.

[0033] Figure 9 This is the SEM image of slag corrosion in Example 5 of the present invention.

[0034] Figure 10 This is the SEM image of slag corrosion in Example 6 of the present invention.

[0035] Figure 11 This is the SEM image of slag corrosion in Example 7 of the present invention.

[0036] Figure 12 This is the SEM image of slag corrosion in Example 8 of the present invention. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0038] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed in the present invention.

[0039] Where specific techniques or conditions are not specified in the examples of the present invention, the techniques or conditions described in the literature in the field or in the product specifications were followed. All devices, instruments, reagents, etc. used, where the manufacturer is not specified, are conventional products available through regular channels. All experimental reagents and raw materials involved are commercially available, and all reagents are analytically pure.

[0040] Example 1 Ordinary chrome-zirconium corundum bricks fired in high-temperature tunnel kilns are used. Figure 1 ) as raw materials (Al2O3 mass fraction of 80%, Cr2O3 mass fraction of 10%, ZrO2 mass fraction of 5%), using silica sol (SiO2 mass fraction of 20%) to impregnate the sol, the overall impregnation equipment used in this embodiment is as follows Figure 2As shown. The refractory preparation is completed in the following steps: (1) Place the chromium zirconium corundum code in the vacuum equipment, close the lid to confirm that the equipment is in a sealed state, turn on the heating constant temperature device, and keep the temperature in the equipment at 25°C; (2) Open the valve on the side of the pressure device and evacuate the vacuum equipment to 2600Pa; (3) Open the valve on the side of the sol, inject the sol into the equipment, and turn on the stirring device (keep the stirring device speed at 200r / min) to keep the sol in a stirred state, and stop injecting after the sol completely immerses and wraps the chromium zirconium corundum brick; (4) Use the pressure equipment to pressurize the pressure equipment to 1.3MPa and maintain it for about 20min; (5) Release the pressure, take out the chromium zirconium corundum brick and dry it at 110℃×24h to obtain this product ( Figure 5 ).

[0041] Comparative Example 1 This comparative example is a common chrome-zirconium corundum brick fired in a high-temperature tunnel kiln without vacuum sol impregnation. The service life of common chrome-zirconium corundum bricks in hazardous waste incineration equipment is generally only 6 months to 1 year. Figure 3-4 shown.

[0042] Example 2 The difference between this embodiment and embodiment 1 is that ordinary chromium-zirconium corundum bricks fired in a high-temperature tunnel kiln are used as raw materials (with an Al2O3 mass fraction of 80%, a Cr2O3 mass fraction of 10%, and a ZrO2 mass fraction of 5%), and are impregnated with aluminum sol (with an Al2O3 mass fraction of 20%). The product is prepared according to the operating steps in embodiment 1 to obtain the product ( Figure 6 ).

[0043] Example 3 The difference between this embodiment and embodiment 1 is that ordinary chromium-zirconium corundum bricks fired in a high-temperature tunnel kiln are used as raw materials (with an Al2O3 mass fraction of 80%, a Cr2O3 mass fraction of 10%, and a ZrO2 mass fraction of 5%), and a mixed sol of silica sol (with a SiO2 mass fraction of 20%) and alumina sol (with an Al2O3 mass fraction of 20%) is used for impregnation, with a mass ratio of silica sol to alumina sol of 1:1. The product ( Figure 7 ).

[0044] Example 4 The difference between this embodiment and embodiment 1 is that ordinary chromium-zirconium corundum bricks fired in a high-temperature tunnel kiln are used as raw materials (with an Al2O3 mass fraction of 80%, a Cr2O3 mass fraction of 10%, and a ZrO2 mass fraction of 5%), and are impregnated with aluminum sulfate sol (with an aluminum sulfate concentration of 25%). The product is prepared according to the operating steps in embodiment 1 to obtain the product ( Figure 8 ).

[0045] Example 5 The difference between this embodiment and embodiment 1 is that only the constant temperature of 25°C during immersion is changed to 35°C. The product ( Figure 9 ).

[0046] Example 6 The difference between this embodiment and embodiment 1 is that only the constant temperature of 25°C during immersion is changed to 15°C. The product ( Figure 10 ).

[0047] Example 7 The difference between this embodiment and embodiment 1 is that ordinary chromium-zirconium corundum bricks fired in a high-temperature tunnel kiln are used as raw materials (with an Al2O3 mass fraction of 80%, a Cr2O3 mass fraction of 10%, and a ZrO2 mass fraction of 5%), and a mixed sol of silica sol (with a SiO2 mass fraction of 20%) and alumina sol (with an Al2O3 mass fraction of 20%) is used for impregnation, with a mass ratio of silica sol to alumina sol of 1:1. The temperature is maintained at 35°C during impregnation, and the remaining steps are prepared according to the operating steps in embodiment 1. The product ( Figure 11 ).

[0048] Example 8 The difference between this embodiment and embodiment 1 is that ordinary chromium-zirconium corundum bricks fired in a high-temperature tunnel kiln are used as raw materials (with an Al2O3 mass fraction of 80%, a Cr2O3 mass fraction of 10%, and a ZrO2 mass fraction of 5%), and a mixed sol of silica sol (with a SiO2 mass fraction of 20%) and alumina sol (with an Al2O3 mass fraction of 20%) is used for impregnation, with a mass ratio of silica sol to alumina sol of 1:1. A constant temperature of 15°C is maintained during impregnation, and the remaining steps are prepared according to the operating steps in embodiment 1, to obtain a product ( Figure 12 ).

[0049] Table 1 shows the performance of ordinary chromium-zirconium corundum bricks (Comparative Example 1) fired in a high-temperature tunnel kiln but not impregnated with vacuum sol, as well as the products obtained in various examples.

[0050] Table 1

[0051] Note: The penetration area percentage is the ratio of the area of ​​the sample section penetrated by slag to the total area of ​​the sample section.

[0052] Table 2 shows the EDS harmful component analysis of the slag erosion area of ​​ordinary chromium-zirconium corundum bricks (Comparative Example 1) and various examples after firing in a high-temperature tunnel kiln without vacuum sol impregnation.

[0053] Table 2

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a refractory product resistant to salt penetration and corrosion, characterized in that: include: The chromium zirconium corundum brick is mixed with the sol under vacuum and stirring conditions and heated, then pressurized and dried after pressure relief; The sol is selected from one or more of silica sol, aluminum sol, and aluminum sulfate sol.

2. The preparation method according to claim 1, characterized in that The sol is selected from at least two of silica sol, aluminum sol, and aluminum sulfate sol, preferably silica sol and aluminum sol, and the mass ratio of the silica sol to the aluminum sol is 3:1 to 1:1; Preferably, the mass fraction of SiO2 in the silica sol is 10% to 40%, preferably 20%; And / or, in the aluminum sol, the mass fraction of Al2O3 is 20% to 25%, preferably 20%; And / or, in the aluminum sulfate sol, the mass fraction of aluminum sulfate is 20% to 40%.

3. The preparation method according to claim 1 or 2, characterized in that The chromium-zirconium corundum brick is a chromium-zirconium corundum brick fired at high temperature in a tunnel kiln; preferably, the mass fraction of Al2O3 in the chromium-zirconium corundum brick is 80%-90%, the mass fraction of Cr2O3 is 3%-15%, and the mass fraction of ZrO2 is 2%-10%.

4. The preparation method according to any one of claims 1 to 3, characterized in that The vacuum degree of the vacuum state is 2500~3000Pa; And / or, the pressure of the pressurization treatment is 1-1.4 MPa, and the pressurization time is 15-25 min.

5. The preparation method according to any one of claims 1 to 4, characterized in that The heating temperature is 15-50°C.

6. The preparation method according to any one of claims 1 to 5, characterized in that The stirring speed is 100-400 r / min.

7. The preparation method according to any one of claims 1 to 6, characterized in that The drying temperature is 105-115° C. and the drying time is 20-30 hours.

8. A refractory product resistant to salt penetration and corrosion, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 7.

9. The salt penetration erosion resistant refractory product according to claim 8, characterized in that: The salt penetration erosion resistant refractory product has an apparent porosity of 5.1% to 6.9% and a bulk density of 3.30 to 3.42 g / cm 3 , the compressive strength is 127~140MPa, and the permeability area percentage is 7%~17%.

10. Use of the preparation method according to any one of claims 1 to 7 or the salt penetration erosion resistant refractory product according to claim 8 or 9, characterized in that: Application in the preparation of refractory materials for hazardous waste incineration equipment, waste gas and waste liquid incineration equipment or domestic waste incineration equipment.

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