A low-chromium aluminum-chromium refractory material for rock wool furnace lining and its preparation method

Abstract

The present invention relates to the technical field of rock wool furnaces, and in particular to a low-chromium aluminum-chromium refractory material for rock wool furnace lining and a preparation method thereof. The preparation method of the present invention comprises the following steps: S1, stirring and mixing corundum particles and fused zirconium mullite particles to obtain a premixed granular material; S2, mixing and grinding corundum fine powder, chromium concentrate fine powder, andalusite fine powder and zircon fine powder to a particle size of ≤65μm to obtain a premixed fine powder; S3, mixing the premixed granular material and the premixed fine powder to obtain a premix; S4, sequentially adding Si powder and aluminum silicate fiber to the premix to obtain a mixture; S5, adding phosphoric acid solution to the mixture, stirring and mixing, adding it to a mold for vibration molding, and drying it after natural curing to obtain a green material; S6, keeping the green material at high temperature for a period of time. The refractory material prepared by the present invention is environmentally friendly, has high sintering density, good thermal shock stability, small thermal expansion coefficient, and strong corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of rock wool furnaces, and in particular to a low-chromium aluminum-chromium refractory material for rock wool furnace lining and a preparation method thereof. Background Art

[0002] Rock wool is a fiber material made primarily from basalt, supplemented with slag, dolomite, limestone, and other raw materials. The material is then melted, sprayed, and then formed into a compacted mass. It is commonly used for thermal insulation, heat preservation, and soundproofing in buildings and industrial settings. It is non-flammable, durable, and lightweight. With the implementation and advancement of China's dual carbon goals, demand for rock wool products is increasing.

[0003] Commonly used kilns for producing rock wool include kiln pools, electric furnaces, and cupolas. Kiln pools have high investment and production costs, consume a lot of energy, and are currently less used. Electric furnaces are a type of rock wool production equipment that has emerged in recent years, and have advantages in energy conservation and emission reduction, improving production efficiency, and utilizing solid waste. Cupolas use fossil fuels such as coke and natural gas as heat sources, and the raw materials are usually block-shaped natural minerals or slag with a particle size of 30 to 80 mm. The operating temperature of the oxidation zone usually reaches above 1500°C. Cupolas are currently the most common equipment for melting rock wool, accounting for more than 90% of domestic rock wool production equipment ( Si Fuyin, Sun Shibing, Qiu Zhiming, etc. Comparison of rock wool melting in cupola and electric melting furnace[J]. Glass, 2024, 5:44-50 ).

[0004] Taking the cupola as an example, the rock wool cupola is a vertical smelting furnace. Raw materials and coke are added from the top and gradually heated, reduced, and melted before moving downward. During this movement, the lumpy raw materials and coke are fully mixed and rub against the lining, causing wear on the cupola lining. At the same time, to fully improve the thermal efficiency of the cupola, the furnace is usually equipped with hot air preheating, oxygen-enriched air combustion, electromagnetic / mechanical stirring devices, etc., which will cause strong mechanical erosion on the cupola lining. In addition, since the raw materials for rock wool production are usually natural ores, slag, and solid waste, in recent years, due to the requirements of energy conservation and carbon reduction, the preparation of rock wool products from hot slag has become a hot spot for industrial transformation. The composition of the liquid slag is difficult to accurately control, which requires the addition of SiO2, Al2O3, etc. during the production process for tempering. In short, the raw materials for rock wool smelting are widely sourced, have complex components, high acidity, and poor uniformity, which cause strong erosion to the furnace lining. The feeding of hot molten slag is intermittent, so the rock wool cupola is an intermittent working equipment. Some cupolas have water-cooled coils outside the furnace wall, which makes the rock wool lining material bear strong thermal shock. Therefore, the rock wool furnace lining material should have good mechanical properties, resistance to slag erosion and thermal shock stability ( Sun Shibing, Tian Yingliang, Han Jixian, et al. Development status of rock wool manufacturing in my country and production carbon reduction approaches[J]. Journal of Beijing University of Technology, 2022, 48(3): 306-311 ).

[0005] At present, there is no consensus at home and abroad on the selection of refractory materials for rock wool furnace lining. Usually, quartz refractory materials, carbon-containing refractory materials, non-oxide composite materials and aluminum refractory materials are selected based on the experience of iron-making cupolas.

[0006] For example, quartz refractory materials have good resistance to acidic slag erosion, but the sources of rock wool smelting raw materials are wide, and the alkalinity range of rock wool slag is wide, so quartz refractory materials are difficult to be widely used; in addition, quartz refractory materials have poor thermal shock stability. For rock wool furnaces with slag bag feeding and intermittent operation, they are very susceptible to thermal shock and peeling.

[0007] Carbon-containing refractory materials and non-oxide composite materials can also be used as rock wool cupola lining materials. Patent CN114956794 B discloses a method for preparing a corrosion-resistant rock wool electric furnace lining material. Silicon carbide, white corundum, silicon oxynitride, boron carbide, aluminum powder, and a resin binder are mixed and stirred to produce a corrosion-resistant rock wool electric furnace lining material. However, rock wool furnaces are high-temperature kilns that operate intermittently in an air atmosphere. Carbon-containing and silicon carbide composite materials are susceptible to oxidation, which can shorten the service life of the furnace lining.

[0008] Aluminum refractory materials mainly include corundum refractory materials, high alumina refractory materials and aluminum chromium refractory materials. Aluminum refractory materials have good chemical stability, high strength, good anti-erosion performance, and strong corrosion resistance to acidic slag and alkaline slag. However, aluminum refractory materials also have the disadvantage of poor thermal shock stability, and the effect of using them on rock wool furnaces is still not ideal. (Sun Fan, Li Xiaoyan, Liu Xiaobin. Introduction to refractory materials and furnace construction process for EC&S cupola[J]. China Foundry Equipment and Technology, 2018, 53(4):97-101) .

[0009] Among aluminum-chromium refractories, Cr2O3 has a very low solubility in slags of different alkalinity, so it has good resistance to slag erosion. Aluminum-chromium refractories also have excellent high-temperature performance and erosion resistance. Therefore, aluminum-chromium refractories are one of the ideal choices for rock wool furnace lining refractories. Aluminum-chromium refractories are usually prepared with corundum and chrome green as raw materials. Its main chemical composition is aluminum oxide and chromium oxide, with few impurities. Due to its good high-temperature strength and resistance to slag erosion, aluminum-chromium bricks are mostly used in harsh service environments such as hazardous waste incinerators, glass kiln regenerators, water-coal slurry gasification furnaces and non-ferrous metal smelting. Patent CN 118812249 A discloses a method for preparing a rock wool furnace lining using corundum and Cr2O3 as raw materials. This method uses SiO2, Fe2O3, CaO, and MgO as additives, and uses high-chromium corundum castables with varying Cr2O3 and Al2O3 contents to create a rock wool furnace lining with excellent fly ash erosion resistance. This method uses multiple additives, which reduces the furnace lining's strength and refraction under load temperature, resulting in reduced deformation and erosion resistance. Summary of the Invention

[0010] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and propose a low-chromium aluminum-chromium refractory material for rock wool furnace lining and a preparation method thereof. The method has a simple process and does not require special instruments or equipment for processing. The prepared low-chromium aluminum-chromium refractory material for rock wool furnace lining is environmentally friendly, has high sintering density, good thermal shock stability, small thermal expansion coefficient, and strong corrosion resistance.

[0011] The present invention provides a method for preparing a low-chromium aluminum-chromium refractory material for rock wool furnace lining, comprising the following steps:

[0012] S1. Corundum particles and fused zirconium mullite particles are mixed in a mass ratio of 100:(10-15) to obtain a premixed particle material;

[0013] S2. Corundum fine powder, chromium concentrate fine powder, andalusite fine powder, and zircon fine powder are mixed and ground into a particle size of ≤65 μm in a mass ratio of 100:(12-18):(13-16):(5-8) to obtain a premixed fine powder;

[0014] S3, mixing the premixed granular material and the premixed fine powder material in a mass ratio of 100:(55-65) to obtain a premix;

[0015] S4, adding 0.8-1.2% of Si powder and 1.2-1.5% of aluminum silicate fiber by weight of the premix to the premix in sequence, and mixing to obtain a mixture;

[0016] S5, adding a phosphoric acid solution accounting for 6.5-7.2% by mass of the mixture to the mixture, stirring and mixing, adding the mixture to a mold for vibration molding, and drying after natural curing to obtain a green material;

[0017] S6. Keeping the green material at high temperature for a period of time to obtain a low-chromium aluminum-chromium refractory material for rock wool furnace lining.

[0018] Furthermore, in step S6, the temperature is kept at 1520-1570° C. for 8-10 hours.

[0019] Furthermore, the particle size of the corundum particles is 0.2-6 mm, wherein the particle material ratio of [0.2 mm-2 mm]: [3 mm-4 mm]: [5 mm-6 mm] is (10-15): (40-60): (15-20).

[0020] Furthermore, the particle size of the fused zirconium mullite particles is 2-5 mm, wherein the particle material ratio of [2 mm-3 mm]:[4 mm-5 mm] is 10:(2-3).

[0021] Furthermore, the particle size of the Si powder is ≤45 μm; and the Si content of the Si powder is ≥99.5%.

[0022] Furthermore, the diameter of the aluminum silicate fiber is 10 to 20 μm, and the length is 3 to 6 mm.

[0023] Furthermore, the concentration of the phosphoric acid solution is 1.5 to 2.5 mol / L.

[0024] A low-chromium aluminum-chromium refractory material for rock wool furnace lining prepared by the above-mentioned preparation method.

[0025] The beneficial effects of the present invention are:

[0026] (1) The present invention utilizes the high-temperature in-situ mullitization reaction of andalusite and zircon to improve the bonding of the matrix material and promote the densification of the material; and the SiO2 glass formed during the mullitization process forms a coating on the chromium-containing components, hindering the oxidation transformation of Cr2O3 in the chromium concentrate to a high-valent state, thereby eliminating the environmental risks of the chromium-containing components.

[0027] (2) The present invention utilizes the cross-distribution of corundum particles and fused zirconium mullite particles to form a continuous network skeleton, thereby improving the bonding of particle components; at the same time, the particle size gradient and grade difference of the fine powder are utilized to improve the dispersion performance of the matrix fine particles, which is beneficial to the filling of the aggregate-matrix and effectively improves the density and sintering performance of the material.

[0028] (3) The present invention utilizes the chemical replacement of phosphoric acid solution and Si powder to generate gas, and realizes the miniaturization of the internal pores of the material through the bridging and drainage of aluminum silicate fibers. On the one hand, it reduces the porosity of the material, reduces the thermal expansion of the material, and improves the thermal shock stability of the material.

[0029] (4) The present invention utilizes the saturated solid solution of corundum and chromium concentrate in a high-temperature liquid medium to improve the grain boundary bonding strength of the aluminum-chromium solid solution, avoid the erosion of the material by the slag from the grain boundary, and further improve the corrosion resistance of the material.

[0030] The low-chromium aluminum-chromium refractory material for rock wool furnace lining prepared by the present invention has been tested:

[0031] Bulk density is 2.88~3.17g / cm 3 Apparent porosity: 18.7-22.2% (GB / T2997-2015); Flexural strength retention after 5 thermal shock tests at 1100°C: 78-85% (GB / T30873-2014); High-temperature thermal expansion coefficient at 1600°C: (6.3-6.8)×10 -6 / ℃(GB / T 7320-2008); corrosion index after 1600℃×3h static crucible method slag resistance test: 3.3~5.7%(GB / T 8931-2007).

[0032] Therefore, the process of the present invention is simple and does not require special instruments or equipment for processing; the low-chromium aluminum-chromium refractory material for rock wool furnace lining prepared is environmentally friendly, has high sintering density, good thermal shock stability, small thermal expansion coefficient, and strong corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a SEM micrograph of a low-chromium aluminum-chromium refractory material sample for rock wool furnace lining prepared in Example 1;

[0034] Figure 2 This is a SEM microscopic photograph of the low-chromium aluminum-chromium refractory material sample for rock wool furnace lining prepared in Example 1 after being eroded by rock wool. DETAILED DESCRIPTION

[0035] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0036] Example 1

[0037] A method for preparing a low-chromium aluminum-chromium refractory material for rock wool furnace lining, comprising the following steps:

[0038] S1. Add corundum particles and fused zirconium mullite particles in a planetary mixer at a mass ratio of 100:12 and mix for 6 to 8 minutes to obtain a premixed particle material;

[0039] S2. Add corundum fine powder, chromium concentrate fine powder, andalusite fine powder, and zircon fine powder into a roller mixer in a mass ratio of 100:12:14:8, mix and grind to a particle size of ≤65 μm, and obtain a premixed fine powder;

[0040] S3, adding the premixed granular material and the premixed fine powder into a mixer at a mass ratio of 100:60, and mixing for 10 to 15 minutes to obtain a premix;

[0041] S4, adding 0.8% of Si powder and 1.3% of aluminum silicate fiber by weight of the premix to the premix in sequence, and mixing for 8 to 10 minutes to obtain a mixture;

[0042] S5. Add 7.2% phosphoric acid solution by weight to the mixture, stir for 5 to 8 minutes, add the mixture to a mold for vibration molding, naturally cure for 10 to 12 hours, and dry at 100 to 110° C. for 8 hours to obtain a green material;

[0043] S6. Add the green material into a high-temperature furnace and keep it at 1570° C. for 10 hours to obtain a low-chromium aluminum-chromium refractory material for rock wool furnace lining.

[0044] Figure 1 This is a SEM micrograph of a low-chromium aluminum-chromium refractory sample for rock wool furnace lining. The material demonstrates complete grain growth and a uniform microstructure. The grains are large and tightly bonded, resulting in excellent density and sintering properties, effectively resisting slag erosion. The absence of low-melting phases between grain boundaries ensures high solid-solid bond strength. Microscopic pores are dispersed within the grains, contributing to the material's improved thermal shock resistance.

[0045] Figure 2 This is an SEM micrograph of a low-chromium aluminum-chromium refractory sample for rock wool furnace lining after being corroded by rock wool. It can be seen that the corrosion reaction occurs primarily in the matrix, and a clear "interfacial stratification" is observed between the corroding medium and the material itself, indicating that the material has good resistance to the corrosive medium. The low-melting products produced by the corrosion are blocked in the matrix, forming continuous and compact areas, indicating that the material's overall structure is intact after corrosion, with no significant cracking or flaking, and that it has good resistance to slag corrosion.

[0046] The low-chromium aluminum-chromium refractory material for rock wool furnace lining prepared in this embodiment was tested:

[0047] The bulk density is 3.17 g / cm 3 Apparent porosity: 18.7% (GB / T2997-2015); Flexural strength retention: 85% after 5 thermal shock tests at 1100°C (GB / T30873-2014); High-temperature thermal expansion coefficient: 6.6×10 -6 / ℃(GB / T 7320-2008); corrosion index after 1600℃×3h static crucible method slag resistance test: 3.3%(GB / T 8931-2007).

[0048] Example 2

[0049] A method for preparing a low-chromium aluminum-chromium refractory material for rock wool furnace lining, comprising the following steps:

[0050] S1. Add corundum particles and fused zirconium mullite particles in a planetary mixer at a mass ratio of 100:15 and mix for 6 to 8 minutes to obtain a premixed particle material;

[0051] S2. Add corundum fine powder, chromium concentrate fine powder, andalusite fine powder, and zircon fine powder into a roller mixer at a mass ratio of 100:15:13:6, mix and grind to a particle size of ≤65 μm, and obtain a premixed fine powder;

[0052] S3, adding the premixed granular material and the premixed fine powder into a mixer at a mass ratio of 100:55, and mixing for 10 to 15 minutes to obtain a premix;

[0053] S4, adding 1.2% of Si powder and 1.5% of aluminum silicate fiber by weight of the premix to the premix, and mixing for 8 to 10 minutes to obtain a mixture;

[0054] S5. Add 6.5% phosphoric acid solution by weight of the mixture to the mixture, stir for 5 to 8 minutes, add the mixture to a mold for vibration molding, naturally cure for 10 to 12 hours, and then dry at 100 to 110° C. for 10 hours to obtain a green material;

[0055] S6. Add the green material into a high-temperature furnace and keep it at 1520° C. for 9 hours to obtain a low-chromium aluminum-chromium refractory material for rock wool furnace lining.

[0056] The low-chromium aluminum-chromium refractory material for rock wool furnace lining prepared in this embodiment was tested:

[0057] The bulk density is 3.12 g / cm 3 Apparent porosity: 19.4% (GB / T2997-2015); Flexural strength retention: 78% after 5 thermal shock tests at 1100°C (GB / T30873-2014); High-temperature thermal expansion coefficient: 6.3×10 -6 / ℃(GB / T 7320-2008); corrosion index after 1600℃×3h static crucible method slag resistance test: 5.7%(GB / T 8931-2007).

[0058] Example 3

[0059] A method for preparing a low-chromium aluminum-chromium refractory material for rock wool furnace lining, comprising the following steps:

[0060] S1. Add corundum particles and fused zirconium mullite particles in a planetary mixer at a mass ratio of 100:10 and mix for 6 to 8 minutes to obtain a premixed particle material;

[0061] S2. Add corundum fine powder, chromium concentrate fine powder, andalusite fine powder, and zircon fine powder into a roller mixer at a mass ratio of 100:18:16:5, mix and grind to a particle size of ≤65 μm, and obtain a premixed fine powder;

[0062] S3, adding the premixed granular material and the premixed fine powder into a mixer at a mass ratio of 100:65, and mixing for 10 to 15 minutes to obtain a premix;

[0063] S4, adding 1.0% of Si powder and 1.2% of aluminum silicate fiber by weight of the premix to the premix in sequence, and mixing for 8 to 10 minutes to obtain a mixture;

[0064] S5. Add 6.6% phosphoric acid solution by weight of the mixture to the mixture, stir for 5 to 8 minutes, add the mixture to a mold for vibration molding, naturally cure for 10 to 12 hours, and then dry at 100 to 110° C. for 12 hours to obtain a green material;

[0065] S6. Add the green material into a high-temperature furnace and keep the temperature at 1550° C. for 8 hours to obtain a low-chromium aluminum-chromium refractory material for rock wool furnace lining.

[0066] The low-chromium aluminum-chromium refractory material for rock wool furnace lining prepared in this embodiment was tested:

[0067] The bulk density is 2.88 g / cm 3 The apparent porosity is 22.2% (GB / T2997-2015); the flexural strength retention rate after 5 thermal shock tests at 1100°C is 81% (GB / T30873-2014); the high-temperature thermal expansion coefficient at 1600°C is 6.8×10 -6 / ℃(GB / T 7320-2008); corrosion index after 1600℃×3h static crucible method slag resistance test: 4.2%(GB / T 8931-2007).

[0068] Any matters not mentioned above shall be subject to the existing technology.

[0069] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art of the present invention may make various modifications or additions to the described specific embodiments or replace them in similar ways, but they will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a low-chromium aluminum-chromium refractory material for rock wool furnace lining, characterized in that: The steps include: S1. Corundum particles and fused zirconium mullite particles are mixed in a mass ratio of 100:(10-15) to obtain a premixed particle material; S2. Mix and grind the corundum fine powder, chromium concentrate fine powder, andalusite fine powder, and zircon fine powder in a mass ratio of 100:(12-18):(13-16):(5-8) to a particle size of ≤65 μm to obtain a premixed fine powder; S3, mixing the premixed granular material and the premixed fine powder material in a mass ratio of 100:(55-65) to obtain a premix; S4, adding 0.8-1.2% of Si powder and 1.2-1.5% of aluminum silicate fiber by weight of the premix to the premix in sequence, and mixing to obtain a mixture; S5, adding a phosphoric acid solution accounting for 6.5-7.2% of the mass of the mixture to the mixture, stirring and mixing, adding the mixture to a mold for vibration molding, and drying after natural curing to obtain a green material; S6, keeping the green material at high temperature for a period of time to obtain a low-chromium aluminum-chromium refractory material for rock wool furnace lining; In step S6, the temperature is kept at 1520-1570° C. for 8-10 hours.

2. The method for preparing a low-chromium aluminum-chromium refractory material for rock wool furnace lining according to claim 1, characterized in that: The particle size of the corundum particles is 0.2-6 mm, wherein the particle material ratio of [0.2 mm-2 mm]: [3 mm-4 mm]: [5 mm-6 mm] is (10-15): (40-60): (15-20).

3. The method for preparing a low-chromium aluminum-chromium refractory material for rock wool furnace lining according to claim 1, characterized in that: The particle size of the fused zirconium mullite particles is 2-5 mm, wherein the particle material ratio of [2 mm-3 mm]:[4 mm-5 mm] is 10:(2-3).

4. The method for preparing a low-chromium aluminum-chromium refractory material for rock wool furnace lining according to claim 1, characterized in that: The particle size of the Si powder is ≤45 μm; the Si content of the Si powder is ≥99.5%.

5. The method for preparing a low-chromium aluminum-chromium refractory material for rock wool furnace lining according to claim 1, characterized in that: The aluminum silicate fiber has a diameter of 10-20 μm and a length of 3-6 mm.

6. The method for preparing a low-chromium aluminum-chromium refractory material for rock wool furnace lining according to claim 1, characterized in that: The concentration of the phosphoric acid solution is 1.5-2.5 mol / L.

7. A low-chromium aluminum-chromium refractory material for rock wool furnace lining prepared by the preparation method according to any one of claims 1 to 6.

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