Alkali-resistant castable for lime rotary kiln working lining, preparation method and application thereof

Abstract

The present invention discloses an alkali-resistant castable for a lime rotary kiln working lining, as well as its preparation method and application. The present invention comprises the following raw materials in parts by mass: 100 parts premixed granular material; 50-55 parts premixed fine powder; and 9-13 parts potassium dihydrogen phosphate solution. The premixed granular material comprises magnesia aluminate spinel particles and calcium hexaaluminate particles; and the premixed fine powder comprises magnesia rhodonite fine powder, enstatite fine powder, zirconium boride fine powder, and amorphous Al2O3 fine powder. The alkali-resistant castable for the lime rotary kiln working lining prepared by the present invention has excellent construction performance. After being cast into the lime rotary kiln working lining, it does not require additional heat treatment or firing, thus saving energy. The castable has high high-temperature strength, low bulk density, low thermal conductivity, high alkalinity, strong resistance to alkali corrosion, and is non-ringing and slag-resistant. The castable has good fluidity, ensuring good overall sealing of the lime rotary kiln working lining. The alkali-resistant castable produces no toxic components before and after construction, making it environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory materials, in particular to an alkali-resistant castable for a lime rotary kiln working lining, a preparation method thereof and an application thereof. Background Art

[0002] Lime rotary kiln is one of the main high-temperature equipment for calcining active lime ( Zhao Xiangwei, Luo Zhongyi, Xu Gangliang, et al. Production practice of energy saving and consumption reduction in lime rotary kiln[J]. Refractory and Lime, 2023, 48(2): 41-43 ), limestone ore (CaCO3) is crushed and enters the rotary kiln. As the cylinder rotates, it is evenly heated and decomposed into CaO. During this dynamic high-temperature process, the working lining refractory material in the lime rotary kiln cylinder faces the following service environments and requirements:

[0003] (1) High temperature environment conditions. The temperature in the lime rotary kiln is high. Although the theoretical decomposition temperature of limestone is about 800-900℃, factors such as heat dissipation of the kiln body and lime activity must be considered during actual calcination. Therefore, the operating temperature in the lime rotary kiln is about 1400-1500℃, especially the instantaneous temperature of the burning zone can reach above 1550℃, which is much higher than the decomposition temperature of lime ( Zhang Ping, Dai Wei Lin. Discussion on reducing heat consumption of lime rotary kiln calcining system[J]. Refractory and Lime, 2023, 48(4): 30-31+40 ), this high-temperature operating condition places stringent demands on the high-temperature stability of the working lining refractory materials.

[0004] (2) Erosion by strong alkaline media. The main medium environment in the lime rotary kiln is strong alkaline free CaO, which has strong corrosive effects on refractory materials.

[0005] (3) Lime rotary kilns are subject to strong dynamic mechanical stress. Unlike high-temperature equipment such as tunnel kilns, shuttle kilns, or Maerz kilns, lime rotary kilns are rotary dynamic operations with kiln lengths of approximately 40 to 80 meters, or even longer. During the dynamic turnover process, refractory materials are subject to both high-temperature thermal stress and axial mechanical stress, which accelerates the damage of refractory materials.

[0006] (4) High-temperature wind speed scouring. The fuel (coal powder, coke oven gas or natural gas, etc.) of the lime rotary kiln is blown into the kiln body at high speed, and the flame length is about 15 to 20 meters. Therefore, the refractory materials of the kiln body are faced with the scouring of high-speed hot air flow ( Zhang Ping, Dai Weilin, Su Huawei, et al. Analysis and discussion on the application of low calorific value gas in lime rotary kiln[J]. Refractory and Lime, 2022, 47(3):38-40 ), generally the movement speed of high-temperature smoke-gas-dust can reach 16 to 18 m / s, which places high demands on the erosion resistance and spalling resistance of refractory materials.

[0007] (5) Low heat capacity and low thermal conductivity. The heat loss of the lime rotary kiln is an important indicator of its energy consumption. The low heat capacity and low thermal conductivity of the kiln working lining are the key to reducing heat loss. Therefore, while meeting the service performance of the working lining, it is also necessary to have the characteristics of "low heat absorption and no heat transfer".

[0008] At present, the working lining of the lime rotary kiln can be made of Al2O3-SiO2 refractory materials, such as mullite, corundum-mullite, bauxite-mullite and other fired or unfired bricks ( He Guantong, Guo Hongxiang, Wang Liwang, et al. Active lime rotary kiln Research and development and application of supporting refractory materials[J]. Industrial Furnace, 2022, 44(1): 68-72 ), with its excellent high-temperature performance, strong erosion resistance, low material preparation cost, and low thermal conductivity, it can effectively solve the heat loss problem of the lime rotary kiln shell. However, aluminosilicate refractory materials have low basicity and weak resistance to alkaline media corrosion. On the one hand, they are prone to ringing, and on the other hand, they have poor resistance to temperature fluctuations and thermal shock stability.

[0009] Secondly, it is also common to use magnesia-alumina spinel fired bricks as the refractory material for the working lining of lime rotary kilns. They have high refractoriness, high high-temperature strength, and strong resistance to erosion by alkaline media. In addition, magnesia-alumina spinel fired bricks have stable structure and performance and strong resistance to erosion by high-temperature wind speeds. However, the following problems still need to be solved:

[0010] (1) The firing temperature of magnesia-alumina spinel bricks is high (1500-1600℃), which undoubtedly causes greater energy consumption and increases the cost of materials. In addition, it also wastes the effective heat in the operation state of the lime rotary kiln.

[0011] (2) The thermal conductivity of magnesia-alumina spinel bricks is relatively large (about 4-6 W / (m·K)), which leads to a high external temperature of the lime rotary kiln shell (generally 360-400°C), increasing the heat loss and energy consumption of the rotary kiln.

[0012] (3) Magnesium-aluminum spinel bricks are fired shaped refractory products and are fixed in the lime rotary kiln by masonry. The circular appearance of the rotary kiln increases the difficulty and strength of masonry, and the integrity of the refractory lining of the cylinder is significantly reduced. In particular, the joints of the bricks become weak links for erosion and penetration, resulting in the peeling and damage of the lining bricks.

[0013] (4) Magnesium-aluminum spinel bricks are not easy to form rings in the working lining due to their strong ability to resist the erosion of alkaline media ( Ding Chun Hui, Liu Huajian, Liu Shichang, et al. Analysis on the causes of ring formation in metallurgical lime rotary kiln and its solutions[J]. Ansteel Technology, 2022(5): 50-53 ), but it is also difficult to form slag on the surface of the working lining, and a good slag skin refractory material protective layer cannot be formed, which further increases the heat transfer and heat loss of the working lining.

[0014] The patented technology "A bauxite-based homogeneous mullite unburned brick for lime rotary kiln and its preparation method (202211624530.4)" discloses the use of Al2O3-SiO2 refractory materials as raw materials to prepare unburned bricks, and the use of the working temperature of the lime rotary kiln to promote the sintering of unburned bricks, mainly to solve the problem of poor thermal shock resistance. However, the problems of ring formation and kiln body heat loss of aluminum-silicon refractory materials in the lime rotary kiln are still difficult to overcome in a coordinated manner.

[0015] The patented technology "A method for preparing composite prefabricated lining for high-temperature lime rotary kiln (202010702412.5)" discloses the process of casting, baking and shaping the composite prefabricated lining. Although its high-temperature service performance is good, the material components contain magnesia chrome sand and Cr2O3, which are easily converted into highly toxic Cr2O3 under high temperature conditions, alkaline medium and oxidizing atmosphere (all of which are met in the operating conditions of lime rotary kiln). 6+ Compounds seriously pollute the ecological environment and health and safety. Summary of the Invention

[0016] The object of the present invention is to address the above-mentioned deficiencies in the prior art and to provide a method for preparing an alkali-resistant castable for a lime rotary kiln working lining. The preparation method has a simple process; the prepared alkali-resistant castable for the lime rotary kiln working lining has good construction performance, and after being cast into the lime rotary kiln working lining, no additional heat treatment or firing is required, thus saving energy; the castable has high high-temperature strength, low bulk density, low thermal conductivity, high alkalinity, strong resistance to alkali erosion, no ringing and easy slag skin; the castable has good fluidity, and the overall sealing of the lime rotary kiln working lining is good.

[0017] The present invention discloses an alkali-resistant castable material for a lime rotary kiln working lining, comprising the following raw materials in parts by mass: 100 parts of premixed granular material; 50-55 parts of premixed fine powder material; and 9-13 parts of potassium dihydrogen phosphate solution. The premixed granular material comprises magnesium aluminum spinel particles and calcium hexaaluminate particles; and the premixed fine powder material comprises magnesium rhodonite fine powder, enstatite fine powder, zirconium boride fine powder, and amorphous Al2O3 fine powder.

[0018] Furthermore, the mass ratio of the magnesium aluminum spinel particles to the calcium hexaaluminate particles is 100:(55-65).

[0019] Furthermore, the mass ratio of magnesium rhodonite fine powder: enstatite fine powder: zirconium boride fine powder: amorphous Al2O3 fine powder is 100: (70-80): (15-20): (5-8).

[0020] Furthermore, the particle size of the magnesia-alumina spinel particles is 0.1 to 3 mm, and the particle size is continuously distributed, wherein the mass ratio of [0.1 mm to 1 mm] particles, (1 mm to 2 mm] particles and (2 mm to 3 mm] particles is 1.0: (5.2 to 5.8): (1.2 to 1.4).

[0021] Furthermore, the particle size of the calcium hexaaluminate particles is 4 to 8 mm, and the particle size is discontinuously distributed, wherein the mass ratio of [4 mm to 5 mm] particles to [7 mm to 8 mm] particles is 100:(30 to 35).

[0022] Furthermore, the particle size of magnesia rhodonite is 40-60 μm, wherein the mass ratio of CaO, MgO and SiO2 is (10-12):(40-45):(35-40); the particle size of enstatite is 60-80 μm, wherein the mass ratio of MgO and SiO2 is (45-50):(45-50); the particle size of zirconium boride fine powder is 50-70 μm.

[0023] Furthermore, the amorphous Al2O3 fine powder is amorphous, the particle size of the amorphous Al2O3 fine powder is 20 to 30 μm, and the Al2O3 content of the amorphous Al2O3 fine powder is ≥99 wt%.

[0024] Furthermore, the concentration of the potassium dihydrogen phosphate solution is 10-15 wt%.

[0025] A method for preparing the above-mentioned alkali-resistant castable for the working lining of a lime rotary kiln comprises the following steps: uniformly mixing a premixed granular material and a premixed fine powder according to a mass ratio to obtain a mixture; then adding a certain amount of magnesium dihydrogen phosphate solution to the mixture and stirring for a period of time to obtain the alkali-resistant castable for the working lining of the lime rotary kiln.

[0026] A method for preparing a lime rotary kiln working lining, characterized by comprising the following steps:

[0027] S1 prepared using the above-mentioned preparation method to obtain a lime rotary kiln lining alkali-resistant castable;

[0028] S2. The lime rotary kiln working lining alkali-resistant castable casting;

[0029] S3. The molded sample is cured at 25-30°C for 4-6 hours and then demolded. Then, it is cured at 100-110°C for 4-6 hours to obtain the lime rotary kiln working lining.

[0030] The preparation of the present invention does not require special equipment or instruments, and the process is simple.

[0031] The beneficial effects of the present invention are:

[0032] (1) The present invention starts from the alkalinity of the raw material components, selects high-alkalinity refractory raw materials (calcium hexaaluminate, magnesium aluminum spinel, etc.), reduces the introduction of acidic refractory components, and improves the alkali corrosion resistance of the castable from the perspective of "using alkali to resist alkali". At the same time, combined with casting molding, it is beneficial to the construction of the working lining of the lime rotary kiln, improves the overall sealing of the kiln body, improves the anti-scouring and anti-stripping capabilities of the kiln body, and extends the service life of the working lining.

[0033] (2) After the alkali-resistant castable prepared by the present invention is cast into the working lining of the lime rotary kiln, no additional heat treatment or firing is required. In-situ sintering is performed using the heat under the high-temperature operating conditions of the rotary kiln, saving energy and reducing the development cost of the castable.

[0034] (3) The present invention utilizes soluble phosphates to form strength, effectively improving the fluidity of the castable and achieving cement-free bonding, avoiding the formation of low-melting materials and ring formation at high temperatures, and at the same time improving the high-temperature strength of the castable.

[0035] (4) The present invention utilizes the larger crystal structure pores of calcium hexaaluminate, magnesium rhodonite and enstatite to form high-temperature solid solution sintering, combines the sintering activity of the MgO-Al2O3-CaO system to promote the adhesion of the castable and the slag skin, and utilizes in-situ reaction to form a high melting point protective layer, which not only reduces the erosion of the castable, but also reduces the thermal conductivity of the material, thereby reducing the heat loss of the lime rotary kiln shell.

[0036] (5) The present invention utilizes the amorphous properties and disordered structure of amorphous Al2O3 to reduce the activation energy of high-temperature sintering reactions, promote the rapid sintering of the castable system, and combines it with alumina-zirconium boride ceramics to improve the castable's ability to resist temperature fluctuations and thermal shock stability.

[0037] The alkali-resistant castable material for the lime rotary kiln working lining prepared by the present invention is tested and has a bulk density (110°C×24h) of 2.67-2.79 g / cm 3 , vibration flow value is 132~137mm, high temperature flexural strength (1400℃×0.5h) is 8.1~9.2MPa, basicity is 2.4~2.6, thermal conductivity is 1.9~2.2W / (m·K), and flexural bonding strength is 2.4~2.8MPa.

[0038] Therefore, the alkali-resistant castable for the lime rotary kiln working lining prepared by the present invention has good construction performance. After being cast into the lime rotary kiln working lining, no additional heat treatment or firing is required, thus saving energy. The castable has high high-temperature strength, low bulk density, low thermal conductivity, high alkalinity, strong resistance to alkali corrosion, no ringing and easy slag skin. The castable has good fluidity, and the overall sealing performance of the lime rotary kiln working lining is good. The alkali-resistant castable does not produce toxic components before and after construction, and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a photo of the appearance of the test sample of the alkali-resistant castable material for the lime rotary kiln working lining of Example 1.

[0040] Figure 2 This is a photograph of the appearance of the test sample of the alkali-resistant castable material for the working lining of the lime rotary kiln in Example 1 after slag corrosion. DETAILED DESCRIPTION

[0041] 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.

[0042] Example 1

[0043] Step 1: Prepare the premixed granules in a mass ratio of 100:65 of magnesium aluminum spinel particles and calcium hexaaluminate particles, add them into a blender and mix them evenly to obtain a premixed granule.

[0044] Step 2: Add the following ingredients according to the mass ratio of 100:70:15:8:magnesium rhodonite fine powder, enstatite fine powder, zirconium boride fine powder and amorphous Al2O3 fine powder into a roller mixer and mix for 1 hour to obtain a premixed fine powder;

[0045] Step 3: Add the premixed granules and premixed fine powder in a mass ratio of 100:55 into a blender and mix for 16 minutes to obtain a mixture;

[0046] The fourth step is to add a certain amount of potassium dihydrogen phosphate solution to the mixture, mix well and then cast into shape to obtain the alkali-resistant castable for the working lining of the lime rotary kiln.

[0047] The mass ratio of the potassium dihydrogen phosphate solution to the premixed granular material is 11:100; and the concentration of the potassium dihydrogen phosphate solution is 13 wt%.

[0048] The particle size of the magnesia-alumina spinel particles is 0.1 to 3 mm, and the particle size is continuously distributed, wherein the mass ratio of [0.1 mm to 1 mm] particles, (1 mm to 2 mm] particles and (2 mm to 3 mm] particles is 1.0:5.2:1.2.

[0049] The particle size of the calcium hexaaluminate particles is 4 to 8 mm, and the particle size is discontinuously distributed, wherein the mass ratio of [4 mm to 5 mm] particles to [7 mm to 8 mm] particles is 100:30.

[0050] The particle size of magnesia rhodonite is 40-60 μm, wherein the mass ratio of CaO, MgO and SiO2 is 10:40:35; the particle size of enstatite is 60-80 μm, wherein the mass ratio of MgO and SiO2 is 45:50; the particle size of zirconium boride fine powder is 50-70 μm.

[0051] The amorphous Al2O3 fine powder is amorphous, has a particle size of 20 to 30 μm, and has an Al2O3 content of ≥99 wt%.

[0052] The alkali-resistant castable material for the working lining of the lime rotary kiln prepared in this example was cast into shape, cured at 28° C. for 6 hours, and then demolded. The alkali-resistant castable material was then cured at 105° C. for 5 hours to obtain a test sample of the working lining of the lime rotary kiln.

[0053] After testing, the volume density (110℃×24h) is 2.78g / cm 3 , vibration flow value 135mm, high temperature flexural strength (1400℃×0.5h) is 8.8MPa, basicity 2.6, thermal conductivity 2.1W / (m·K), flexural bonding strength 2.7MPa.

[0054] Figure 1 This is a photograph of the appearance of a test sample of the alkali-resistant castable material for the working lining of the lime rotary kiln in this embodiment. The sample's appearance is tightly bonded, with no defects or damage after curing, and its demoulding state is excellent, which is conducive to ensuring the construction performance of the castable.

[0055] Figure 2 This is a photograph of the appearance of a test sample of the alkali-resistant castable material for the working lining of a lime rotary kiln in this embodiment after slag erosion. The eroding medium used was residual slag from a lime rotary kiln at a lime mine. The main chemical composition is: CaO content of 61.56wt%, Al2O3 content of 15.26wt%, MgO content of 1.05wt%, SiO2 content of 8.51wt%, and loss on ignition of 10.23wt%. After slag erosion, the castable crucible sample has no holes and clear boundaries, demonstrating excellent resistance to slag erosion.

[0056] Example 2

[0057] The first step is to prepare the magnesia aluminate spinel particles and calcium hexaaluminate particles in a mass ratio of 100:55, add the particles into a blender and mix them evenly to obtain a premixed granular material;

[0058] Step 2: Add the following ingredients according to the mass ratio of 100:75:15:5: magnesium rhodonite fine powder: enstatite fine powder: zirconium boride fine powder: amorphous Al2O3 fine powder to a roller mixer and mix for 2 hours to obtain a premixed fine powder;

[0059] Step 3: Add the premixed granules and premixed fine powder in a mass ratio of 100:50 into a blender and mix for 18 minutes to obtain a mixture;

[0060] The fourth step is to add a certain amount of potassium dihydrogen phosphate solution to the mixture, mix well and then cast into shape to obtain the alkali-resistant castable for the working lining of the lime rotary kiln.

[0061] The mass ratio of the potassium dihydrogen phosphate solution to the premixed granular material is 10:100; and the concentration of the potassium dihydrogen phosphate solution is 12 wt%.

[0062] The particle size of the magnesia-alumina spinel particles is 0.1 to 3 mm, and the particle size is continuously distributed, wherein the mass ratio of [0.1 mm to 1 mm] particles, (1 mm to 2 mm] particles and (2 mm to 3 mm] particles is 1.0:5.8:1.4.

[0063] The particle size of the calcium hexaaluminate particles is 4 to 8 mm, and the particle size is discontinuously distributed, wherein the mass ratio of [4 mm to 5 mm] particles to [7 mm to 8 mm] particles is 100:35.

[0064] The particle size of magnesia rhodonite is 40-60 μm, wherein the mass ratio of CaO, MgO and SiO2 is 12:45:40; the particle size of enstatite is 60-80 μm, wherein the mass ratio of MgO and SiO2 is 50:45; the particle size of zirconium boride fine powder is 50-70 μm.

[0065] The amorphous Al2O3 fine powder is amorphous, has a particle size of 20 to 30 μm, and has an Al2O3 content of ≥99 wt%.

[0066] The alkali-resistant castable material for the working lining of the lime rotary kiln prepared in this example was cast into shape, cured at 28° C. for 6 hours, and then demolded. The alkali-resistant castable material was then cured at 105° C. for 5 hours to obtain a test sample of the working lining of the lime rotary kiln.

[0067] After testing, the volume density (110℃×24h) is 2.69g / cm 3 , vibration flow value 133mm, high temperature flexural strength (1400℃×0.5h) is 8.2MPa, basicity 2.4, thermal conductivity 2.0W / (m·K), flexural bonding strength 2.6MPa.

[0068] Example 3

[0069] Step 1: Prepare the premixed granules in a mass ratio of 100:60 of magnesium aluminum spinel particles and calcium hexaaluminate particles, add them into a blender and mix them evenly to obtain a premixed granule.

[0070] Step 2: Add the following ingredients according to the mass ratio of 100:75:16:6: magnesium rhodonite fine powder, enstatite fine powder, zirconium boride fine powder and amorphous Al2O3 fine powder into a roller mixer and mix for 2 hours to obtain a premixed fine powder;

[0071] Step 3: Add the premixed granules and premixed fine powder in a mass ratio of 100:52 into a blender and mix for 15 minutes to obtain a mixture;

[0072] The fourth step is to add a certain amount of potassium dihydrogen phosphate solution to the mixture, mix well and then cast into shape to obtain the alkali-resistant castable for the working lining of the lime rotary kiln.

[0073] The mass ratio of the potassium dihydrogen phosphate solution to the premixed granular material is 12:100; and the concentration of the potassium dihydrogen phosphate solution is 15 wt%.

[0074] The particle size of the magnesia-alumina spinel particles is 0.1 to 3 mm, and the particle size is continuously distributed, wherein the mass ratio of [0.1 mm to 1 mm] particles, (1 mm to 2 mm] particles and (2 mm to 3 mm] particles is 1.0:5.5:1.3.

[0075] The particle size of the calcium hexaaluminate particles is 4 to 8 mm, and the particle size is discontinuously distributed, wherein the mass ratio of [4 mm to 5 mm] particles to [7 mm to 8 mm] particles is 100:33.

[0076] The particle size of magnesia rhodonite is 40-60 μm, wherein the mass ratio of CaO, MgO and SiO2 is 11:45:38; the particle size of enstatite is 60-80 μm, wherein the mass ratio of MgO and SiO2 is 1:1; the particle size of zirconium boride fine powder is 50-70 μm.

[0077] The amorphous Al2O3 fine powder is amorphous, has a particle size of 20 to 30 μm, and has an Al2O3 content of ≥99 wt%.

[0078] The alkali-resistant castable material for the working lining of the lime rotary kiln prepared in this example was cast into shape, cured at 28° C. for 6 hours, and then demolded. The alkali-resistant castable material was then cured at 105° C. for 5 hours to obtain a test sample of the working lining of the lime rotary kiln.

[0079] After testing, the bulk density (110℃×24h) is 2.77g / cm 3 , vibration flow value is 137mm, high temperature flexural strength (1400℃×0.5h) is 9.2MPa, basicity is 2.5, thermal conductivity is 2.2W / (m·K), and flexural bonding strength is 2.8MPa.

[0080] Comparative Example 1

[0081] Step 1: Prepare the premixed granules in a mass ratio of 100:60 of magnesium aluminum spinel particles and calcium hexaaluminate particles, add them into a blender and mix them evenly to obtain a premixed granule.

[0082] Step 2: Add the following ingredients according to the mass ratio of 100:30:5:6: magnesium rhodonite fine powder, enstatite fine powder, zirconium boride fine powder and amorphous Al2O3 fine powder into a roller mixer and mix for 1 hour to obtain a premixed fine powder;

[0083] Step 3: Add the premixed granules and premixed fine powder in a mass ratio of 100:52 into a blender and mix for 20 minutes to obtain a mixture;

[0084] The fourth step is to add a certain amount of potassium dihydrogen phosphate solution to the mixture, mix well and then cast into shape to obtain the alkali-resistant castable for the working lining of the lime rotary kiln.

[0085] The mass ratio of the potassium dihydrogen phosphate solution to the premixed granular material is 12:100; and the concentration of the potassium dihydrogen phosphate solution is 10 wt%.

[0086] The particle size of the magnesia-alumina spinel particles is 0.1 to 3 mm, and the particle size is continuously distributed, wherein the mass ratio of [0.1 mm to 1 mm] particles, (1 mm to 2 mm] particles and (2 mm to 3 mm] particles is 1.0:5.5:1.3.

[0087] The particle size of the calcium hexaaluminate particles is 4 to 8 mm, and the particle size is discontinuously distributed, wherein the mass ratio of [4 mm to 5 mm] particles to [7 mm to 8 mm] particles is 100:33.

[0088] The particle size of magnesia rhodonite is 40-60 μm, wherein the mass ratio of CaO, MgO and SiO2 is 11:45:38; the particle size of enstatite is 60-80 μm, wherein the mass ratio of MgO and SiO2 is 1:1; the particle size of zirconium boride fine powder is 50-70 μm.

[0089] The amorphous Al2O3 fine powder is amorphous, has a particle size of 20 to 30 μm, and has an Al2O3 content of ≥99 wt%.

[0090] The lime rotary kiln working lining castable prepared in this comparative example was cast into shape, cured at 28° C. for 6 hours, and then demoulded. The castable was then cured at 105° C. for 5 hours to obtain a test sample of the lime rotary kiln working lining alkali-resistant castable.

[0091] After testing, the bulk density (110℃×24h) is 2.66g / cm 3 , vibration flow value is 121mm, high temperature flexural strength (1400℃×0.5h) is 2.8MPa, basicity is 2.3, thermal conductivity is 3.7W / (m·K), and flexural bonding strength is 0.4MPa.

[0092] It can be seen that the reduction of enstatite fine powder and zirconium boride fine powder weakens the ceramic bonding strength of the material components at high temperature, and at the same time reduces the sintering performance of the material, resulting in a significant reduction in the high-temperature mechanical properties and bonding strength of the castable.

[0093] Any matters not mentioned above shall be subject to the existing technology.

[0094] 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. An alkali-resistant castable for lime rotary kiln working lining, characterized in that: The invention comprises the following raw materials in parts by mass: 100 parts of premixed granular materials; 50-55 parts of premixed fine powder materials; and 9-13 parts of potassium dihydrogen phosphate solution. The premixed granular materials comprise magnesium aluminum spinel particles and calcium hexaaluminate particles. The premixed fine powder materials comprise magnesium rhodonite fine powder: enstatite fine powder: zirconium boride fine powder: amorphous Al2O3 fine powder. The mass ratio of magnesium rhodonite fine powder: enstatite fine powder: zirconium boride fine powder: amorphous Al2O3 fine powder is 100: (70-80): (15-20): (5-8).

2. The alkali-resistant castable material for lime rotary kiln working lining according to claim 1, characterized in that: The mass ratio of magnesium aluminum spinel particles to calcium hexaaluminate particles is 100:(55~65).

3. The alkali-resistant castable material for lime rotary kiln working lining according to claim 1, characterized in that: The particle size of the magnesia-alumina spinel particles is 0.1~3 mm, and the particle size is continuously distributed, among which the mass ratio of [0.1mm~1mm] particles, (1mm~2mm] particles and (2mm~3mm] particles is 1.0:(5.2~5.8):(1.2~1.4).

4. The alkali-resistant castable material for lime rotary kiln working lining according to claim 1, characterized in that: The particle size of calcium hexaaluminate particles is 4~8mm, and the particle size is discontinuously distributed, wherein the mass ratio of [4mm~5mm] particles to [7mm~8mm] particles is 100:(30~35).

5. The alkali-resistant castable material for lime rotary kiln working lining according to claim 1, characterized in that: The particle size of magnesia rhodonite is 40~60μm, among which the mass ratio of CaO, MgO and SiO2 is (10~12):(40~45):(35~40); the particle size of enstatite is 60~80μm, among which the mass ratio of MgO and SiO2 is (45~50):(45~50); the particle size of zirconium boride fine powder is 50~70μm.

6. The alkali-resistant castable material for lime rotary kiln working lining according to claim 1, characterized in that: The amorphous Al2O3 fine powder is amorphous, has a particle size of 20-30 μm, and has an Al2O3 content of ≥99wt%.

7. The alkali-resistant castable material for lime rotary kiln working lining according to claim 1, characterized in that: The concentration of potassium dihydrogen phosphate solution is 10~15wt%.

8. A method for preparing the alkali-resistant castable for lime rotary kiln working lining according to any one of claims 1 to 7, characterized in that: The premixed granular material and the premixed fine powder are mixed evenly according to the mass ratio to obtain a mixture, and then a certain amount of potassium dihydrogen phosphate solution is added to the mixture and stirred for a period of time to obtain the alkali-resistant castable for the working lining of the lime rotary kiln.

9. A method for preparing a lime rotary kiln working lining, characterized in that: The steps include: S1. The alkali-resistant castable for the working lining of the lime rotary kiln is prepared by the preparation method according to claim 8; S2 the lime rotary kiln working lining alkali-resistant castable casting; S3. Curing the molded sample at 25-30°C for 4-6 hours, demolding, and then curing at 100-110°C for 4-6 hours to obtain the lime rotary kiln working lining.

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