Energy-saving lightweight cement kiln mouth castable and preparation method thereof

Abstract

The present application belongs to the technical field of refractory material, and relates to an energy-saving light-weight cement kiln mouth castable and a preparation method thereof. The energy-saving light-weight cement kiln mouth castable is prepared by using 60-70 parts of light-weight lanthanum aluminate-mullite aggregate, 5-10 parts of silicon carbide fine powder, 8-12 parts of bauxite fine powder, 4-8 parts of tabular corundum fine powder, 1-3 parts of alpha-Al2O3 micro powder, 1-6 parts of lanthanum zirconate fine powder, 4-6 parts of calcium aluminate cement as raw materials, adding water reducing agent and water, stirring, forming, demolding, baking, and the like. The castable prepared by the present application has excellent thermal shock stability and erosion resistance, high thermal radiation efficiency, low cost, simple preparation process, and good application prospect, and can greatly improve the service life of the kiln mouth refractory material while reducing heat loss.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, and particularly relates to an energy-saving lightweight cement kiln inlet castable and its preparation method. Background Technology

[0002] my country's cement industry is a typical high-energy-consuming industry. The operating temperature of cement kilns ranges from 1100 to 1500℃, making it the hottest part of the cement production system. Currently, mullite-silicon carbide castables are commonly used as lining materials for cement kiln inlets, which are the areas with the most severe operating environment and heat dissipation. Therefore, energy-saving insulation of cement kiln inlets is of great significance for energy conservation and emission reduction in the cement industry. In recent years, lightweight refractory materials have been adopted as kiln linings to improve the thermal insulation performance of the kiln body. However, to ensure the wear resistance and strength of the kiln lining refractory materials, the improvement in porosity of lightweight refractory materials is relatively limited compared to dense kiln lining refractory materials, resulting in a limited energy-saving insulation effect. To further improve the insulation performance of the cement kiln inlet, it is urgent to develop an energy-saving castable that can meet the operating requirements of cement kiln inlets and satisfy the current needs for energy conservation and emission reduction in the cement industry.

[0003] In recent years, infrared radiation materials have been widely used as energy-saving materials for high-temperature linings. These materials, due to their high infrared emission capabilities, can achieve energy-saving and heat-insulating effects to a certain extent. However, at high temperatures, heat transfer in kiln linings is still mainly through conduction, with thermal radiation accounting for a relatively small portion. Therefore, the energy-saving and heat-insulating effects of infrared radiation materials on kiln linings remain limited. Currently, there are no reports on combining the inherent properties of infrared radiation materials with the porous structure of kiln linings to improve the thermal insulation performance of kiln lining refractory materials.

[0004] CN202410022481.X discloses an environmentally friendly chromium-containing spinel infrared radiation coating. The coating uses aluminum-chromium solid solution fine powder, zirconium oxide fine powder, and silica sol as transition layer materials, and titanium-iron co-doped magnesium-chromium spinel fine powder, aluminum-chromium solid solution fine powder, borosilicate glass powder, silica micropowder, and aluminum dihydrogen phosphate solution as working layer materials. Applying this coating to the lining surface can effectively improve the thermal efficiency of the kiln. However, during the service of a cement kiln, this infrared radiation coating experiences severe wear from pulverized coal and cement raw materials, easily leading to mechanical peeling and failure of the coating structure.

[0005] CN202310563163.X discloses a lightweight high thermal shock refractory material for the preheating and decomposition zone of a cement kiln and its preparation method. The lightweight high thermal shock refractory material is mainly composed of raw materials such as calcite, silicon carbide, andalusite, α-Al₂O₃ micro powder, kaolinite, and binding clay. However, this lightweight refractory material only reduces the material's thermal conductivity by increasing porosity, without comprehensively considering the impact of high-temperature thermal radiation on heat dissipation; therefore, its energy-saving effect on the kiln body is relatively limited.

[0006] To address the issue that the thermal insulation performance of existing cement kiln lining materials cannot meet the energy-saving requirements of cement kilns, energy conservation in cement kilns can be further achieved by synergistically regulating the composition and structure of refractory materials to realize thermal insulation and high infrared emission capabilities. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides an energy-saving, lightweight cement kiln inlet castable and its preparation method. The castable prepared by this invention can significantly reduce heat transfer within the kiln lining while enhancing infrared radiation reflectivity. The product possesses advantages such as high strength, good thermal shock stability, excellent thermal insulation performance, high thermal radiation absorption and emission efficiency, low cost, and simple preparation process. It significantly extends the service life of kiln inlet refractory materials while reducing heat loss, showing promising application prospects.

[0008] To achieve the above objectives, the present invention adopts the following technical solution.

[0009] An energy-saving lightweight cement kiln inlet castable comprises the following components in parts by weight: 60-70 parts of lightweight lanthanum aluminate-mullite aggregate, 5-10 parts of silicon carbide fine powder, 8-12 parts of bauxite fine powder, 4-8 parts of tabular corundum fine powder, 1-3 parts of α-Al2O3 micro powder, 1-6 parts of lanthanum zirconate fine powder, 4-6 parts of calcium aluminate cement, 0.1-0.2 parts of water-reducing agent, and 5-6 parts of water.

[0010] Furthermore, the particle size distribution of the lightweight lanthanum aluminate-mullite aggregate is as follows: particles with a diameter of 3-5 mm account for 40-50 wt% of the lightweight lanthanum aluminate-mullite aggregate, particles with a diameter of 1-3 mm account for 25-40 wt% of the lightweight lanthanum aluminate-mullite aggregate, and particles with a diameter of 0.1-1 mm account for 10-25 wt% of the lightweight lanthanum aluminate-mullite aggregate; the lightweight lanthanum aluminate-mullite aggregate has a porosity ≥50%, an average pore size of 2-20 μm, and a lanthanum aluminate content ≥50 wt%.

[0011] Furthermore, the particle size of the silicon carbide fine powder is ≤0.088mm, and the SiC content of the silicon carbide fine powder is ≥90wt%.

[0012] Furthermore, the particle size of the bauxite powder is ≤0.088mm, and the Al2O3 content in the bauxite powder is ≥60 wt%.

[0013] Furthermore, the particle size of the tabular corundum powder is ≤0.088mm, and the Al2O3 content in the tabular corundum powder is ≥99wt%.

[0014] Furthermore, the particle size of the α-Al2O3 micro powder is ≤2μm, and the Al2O3 content in the α-Al2O3 micro powder is ≥98wt%.

[0015] Furthermore, the particle size of the lanthanum zirconate fine powder is ≤ 88 μm, and the La2Zr2O7 content in the lanthanum zirconate fine powder is ≥99 wt%.

[0016] Furthermore, the Al2O3 content in the calcium aluminate cement is ≥71wt%.

[0017] Furthermore, the water-reducing agent is one of sodium tripolyphosphate, sodium hexametaphosphate, FS10, or FS20.

[0018] A method for preparing an energy-saving, lightweight cement kiln inlet castable includes the following steps:

[0019] Step 1: Mix 4-12 parts of fine mullite powder, 1-3 parts of micro-mullite powder, 2-6 parts of fine lanthanum aluminate powder, and 4-12 parts of dextrin, and ball mill for 4-8 hours to obtain ball-milled powder; then add 6-10 parts of water to the ball-milled powder, granulate, and obtain pre-formed spherical aggregates of different particle sizes, and dry them at 110℃ for 24-36 hours; then calcine the dried spherical aggregates under certain conditions, sieve, and obtain lightweight lanthanum aluminate-mullite aggregates.

[0020] Step 2: First, use 60-70 parts of lightweight lanthanum aluminate-mullite aggregate, 5-10 parts of silicon carbide fine powder, 8-12 parts of bauxite fine powder, 4-8 parts of tabular corundum fine powder, 1-3 parts of α-Al2O3 micro powder, 1-6 parts of lanthanum zirconate fine powder, and 4-6 parts of calcium aluminate cement as raw materials, and add 0.1-0.2 parts of water-reducing agent to the above raw materials. Mix them evenly, then add 5-6 parts of water to the above raw materials, stir evenly, form, cure for 2-3 days, demold, and bake to obtain energy-saving lightweight cement kiln inlet castable.

[0021] Furthermore, in step 1, the Al2O3 content in the fine mullite powder is ≤70wt%; and the Al2O3 content in the micromullite powder is ≤70wt%.

[0022] Furthermore, in step 1, the pre-formed spherical aggregate has particle sizes of 5-3 mm, 3-1 mm, and 1-0 mm.

[0023] Furthermore, in step 1, the calcination temperature is 1200–1400℃, and the calcination time is 3–8 hours.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0025] 1. First, the casting construction method involved in this invention avoids the high-temperature firing process, which is beneficial to energy conservation and environmental protection. Second, the aggregate portion accounts for 60-70% of the total weight of the refractory material. The introduction of lightweight lanthanum aluminate-mullite aggregate ensures the overall lightweight and porous nature of the kiln-mouth refractory material. While ensuring overall strength and wear resistance, it increases the internal thermal resistance of the material by increasing porosity, thus blocking heat conduction. Furthermore, the high emissivity of the aggregate itself enhances the infrared emission and reflection capabilities of the material at high temperatures, reducing radiative heat loss and increasing energy utilization. Under the same preparation conditions, the lightweight kiln-mouth castable prepared by this invention has a better thermal conductivity and average emissivity than other materials.

[0026] 2. Introducing lanthanum zirconate fine powder into the refractory matrix can improve the toughness of the refractory and optimize its thermal shock stability. In addition, lanthanum zirconate itself has a high infrared emissivity, which can also synergistically enhance its ability to reflect radiation.

[0027] 3. Currently, infrared radiation materials are often applied directly to the surface of refractory materials in the form of coatings. However, in cement kilns, the coating is easily peeled off due to the intense friction between the kiln lining and the cement. Therefore, by directly introducing infrared radiation components into the refractory material components, its infrared radiation characteristics will be preserved under complex service conditions. This invention prepares the aggregate, the main component of the refractory material, into a lightweight aggregate with infrared emission capabilities. Lanthanum zirconate in the matrix can also exert the infrared emissivity and toughening properties of zirconium. Therefore, the energy-saving kiln inlet castable provided by this invention can synergistically achieve low thermal conductivity and high infrared emissivity, significantly reducing energy consumption in the kiln inlet area of ​​cement kilns.

[0028] 4. The energy-saving lightweight cement kiln inlet castable prepared by this invention was tested and found to have an apparent porosity of 30-40% and a bulk density of 2.2-2.6 g / cm³. 3 The room temperature flexural strength at 110℃ for 24 hours is 4–9 MPa; the room temperature flexural strength at 1600℃ for 3 hours is 30–45 MPa; the thermal conductivity at 1200℃ is 0.8–1.4 W / (m·K); and the average emissivity in the 0.76–2.5 μm wavelength band at room temperature is 60–78%. This invention features a simple process, and the prepared infrared radiation castable for cement kiln inlets exhibits high strength, good toughness, low thermal conductivity, high thermal reflectivity, and excellent thermal shock stability. It significantly improves the service life of kiln inlet refractory materials while reducing heat loss, showing promising application prospects. Attached Figure Description

[0029] Figure 1The average room temperature emissivity of the energy-saving lightweight cement kiln inlet castable prepared in Example 2 of this invention and other refractory materials prepared by the same process is shown in the 0.76~2.5 μm wavelength band. Detailed Implementation

[0030] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0031] To avoid repetition, the materials involved in this specific implementation are described in a unified manner below, and will not be repeated in the embodiments.

[0032] An energy-saving lightweight cement kiln inlet castable comprises the following components in parts by weight: 60-70 parts of lightweight lanthanum aluminate-mullite aggregate, 5-10 parts of silicon carbide fine powder, 8-12 parts of bauxite fine powder, 4-8 parts of tabular corundum fine powder, 1-3 parts of α-Al2O3 micro powder, 1-6 parts of lanthanum zirconate fine powder, 4-6 parts of calcium aluminate cement, 0.1-0.2 parts of water-reducing agent, and 5-6 parts of water.

[0033] Furthermore, the particle size distribution of the lightweight lanthanum aluminate-mullite aggregate is as follows: particles with a diameter of 3-5 mm account for 40-50 wt% of the lightweight lanthanum aluminate-mullite aggregate, particles with a diameter of 1-3 mm account for 25-40 wt% of the lightweight lanthanum aluminate-mullite aggregate, and particles with a diameter of 0.1-1 mm account for 10-25 wt% of the lightweight lanthanum aluminate-mullite aggregate; the lightweight lanthanum aluminate-mullite aggregate has a porosity ≥50%, an average pore size of 2-20 μm, and a lanthanum aluminate content ≥50 wt%.

[0034] Furthermore, the particle size of the silicon carbide fine powder is ≤0.088mm, and the SiC content of the silicon carbide fine powder is ≥90wt%.

[0035] Furthermore, the particle size of the bauxite powder is ≤0.088mm, and the Al2O3 content in the bauxite powder is ≥60 wt%.

[0036] Furthermore, the particle size of the tabular corundum powder is ≤0.088mm, and the Al2O3 content in the tabular corundum powder is ≥99wt%.

[0037] Furthermore, the particle size of the α-Al2O3 micro powder is ≤2μm, and the Al2O3 content in the α-Al2O3 micro powder is ≥98wt%.

[0038] Furthermore, the particle size of the lanthanum zirconate fine powder is ≤ 88 μm, and the La2Zr2O7 content in the lanthanum zirconate fine powder is ≥99 wt%.

[0039] Furthermore, the Al2O3 content in the calcium aluminate cement is ≥71wt%.

[0040] Furthermore, the water-reducing agent is one of sodium tripolyphosphate, sodium hexametaphosphate, FS10, or FS20.

[0041] A method for preparing an energy-saving, lightweight cement kiln inlet castable includes the following steps:

[0042] Step 1: Mix 4-12 parts of fine mullite powder, 1-3 parts of micro-mullite powder, 2-6 parts of fine lanthanum aluminate powder, and 4-12 parts of dextrin, and ball mill for 4-8 hours to obtain ball-milled powder; then add 6-10 parts of water to the ball-milled powder, granulate, and obtain pre-formed spherical aggregates of different particle sizes, and dry them at 110℃ for 24-36 hours; then calcine the dried spherical aggregates under certain conditions, sieve, and obtain lightweight lanthanum aluminate-mullite aggregates.

[0043] Step 2: First, use 60-70 parts of lightweight lanthanum aluminate-mullite aggregate, 5-10 parts of silicon carbide fine powder, 8-12 parts of bauxite fine powder, 4-8 parts of tabular corundum fine powder, 1-3 parts of α-Al2O3 micro powder, 1-6 parts of lanthanum zirconate fine powder, and 4-6 parts of calcium aluminate cement as raw materials, and add 0.1-0.2 parts of water-reducing agent to the above raw materials. Mix them evenly, then add 5-6 parts of water to the above raw materials, stir evenly, mold, cure for 2-3 days, demold, and bake to obtain energy-saving lightweight cement kiln inlet castable.

[0044] Furthermore, in step 1, the Al2O3 content in the fine mullite powder is ≤70wt%; and the Al2O3 content in the micromullite powder is ≤70wt%.

[0045] Furthermore, in step 1, the pre-formed spherical aggregate has particle sizes of 5-3 mm, 3-1 mm, and 1-0 mm.

[0046] Furthermore, in step 1, the calcination temperature is 1200–1400℃, and the calcination time is 3–8 hours.

[0047] Example 1.

[0048] An energy-saving, lightweight cement kiln inlet castable and its preparation method:

[0049] The preparation method of lightweight lanthanum aluminate-mullite aggregate is as follows: 4 parts of fine mullite powder, 1 part of micro-mullite powder, 3 parts of fine lanthanum aluminate powder, and 4 parts of dextrin are mixed and ball-milled for 4 hours to obtain ball-milled powder; then 6 parts of water are added to the ball-milled powder, and granulation is performed to obtain pre-formed spheres with particle sizes of 5~3mm, 3~1mm, and 1~0mm, respectively, which are dried at 110℃ for 24 hours; then the dried pre-formed spheres are calcined at 1400℃ for 5 hours, crushed, ball-milled, and sieved to obtain lightweight lanthanum aluminate-mullite aggregate.

[0050] Preparation method of energy-saving lightweight cement kiln inlet castable: First, use 60 parts of lightweight lanthanum aluminate-mullite aggregate, 5 parts of silicon carbide fine powder, 10 parts of bauxite fine powder, 6 parts of tabular corundum fine powder, 1 part of α-Al2O3 micro powder, 6 parts of lanthanum zirconate fine powder, and 6 parts of calcium aluminate cement as raw materials, add 0.2 parts of FS10 to the above raw materials, mix evenly, then add 6 parts of water to the above raw materials, stir evenly, mold, cure for 2 days, demold, and bake to obtain energy-saving lightweight cement kiln inlet castable.

[0051] The energy-saving, lightweight cement kiln inlet castable prepared in this embodiment was tested and found to have an apparent porosity of 30% and a bulk density of 2.6 g / cm³. 3 The room temperature flexural strength at 110℃ for 24 hours is 9 MPa; the room temperature flexural strength at 1600℃ for 3 hours is 45 MPa; the thermal conductivity at 1200℃ is 1.4 W / (m·K); and the average emissivity in the 0.76~2.5μm band at room temperature is 60%.

[0052] Example 2.

[0053] An energy-saving, lightweight cement kiln inlet castable and its preparation method:

[0054] The preparation method of lightweight lanthanum aluminate-mullite aggregate is as follows: First, mix 10 parts of fine mullite powder, 3 parts of micro-mullite powder, 6 parts of fine lanthanum aluminate powder, and 12 parts of dextrin, and ball mill for 8 hours to obtain ball milled powder; then add 10 parts of water to the ball milled powder, granulate, and obtain pre-formed spheres with particle sizes of 5~3mm, 3~1mm, and 1~0mm, and dry them at 110℃ for 36 hours; then calcine the dried pre-formed spheres at 1200℃ for 5 hours, crush them, and ball mill them to obtain lightweight lanthanum aluminate-mullite aggregate.

[0055] Preparation method of energy-saving lightweight cement kiln inlet castable: First, use 70 parts of lightweight lanthanum aluminate-mullite aggregate, 5 parts of silicon carbide fine powder, 11 parts of bauxite fine powder, 8 parts of tabular corundum fine powder, 3 parts of α-Al2O3 micro powder, 4 parts of lanthanum zirconate fine powder, and 5 parts of calcium aluminate cement as raw materials, add 0.2 parts of sodium tripolyphosphate to the above raw materials, mix evenly, then add 5 parts of water to the above raw materials, stir evenly, mold, cure for 3 days, demold, and bake to obtain energy-saving lightweight cement kiln inlet castable.

[0056] The energy-saving, lightweight cement kiln inlet castable prepared in this embodiment was tested and found to have an apparent porosity of 40% and a bulk density of 2.2 g / cm³. 3 The room temperature flexural strength at 110℃ for 24 hours is 4 MPa; the room temperature flexural strength at 1600℃ for 3 hours is 30 MPa; the thermal conductivity at 1200℃ is 0.8 W / (m·K); and the average emissivity in the 0.76~2.5μm band at room temperature is 78%.

[0057] Example 3.

[0058] Energy-saving lightweight cement kiln inlet castable and its preparation method:

[0059] The preparation method of lightweight lanthanum aluminate-mullite aggregate is as follows: First, mix 8 parts of fine mullite powder, 2 parts of micro-mullite powder, 4 parts of fine lanthanum aluminate powder, and 8 parts of dextrin, and ball mill for 8 hours to obtain ball milled powder; then add 7 parts of water to the ball milled powder, granulate, and obtain pre-formed spheres with particle sizes of 5~3mm, 3~1mm, and 1~0mm, and dry them at 110℃ for 36 hours; then calcine the dried pre-formed spheres at 1300℃ for 5 hours, crush them, and ball mill them to obtain lightweight lanthanum aluminate-mullite aggregate.

[0060] Preparation method of energy-saving lightweight cement kiln inlet castable: First, use 65 parts of lightweight lanthanum aluminate-mullite aggregate, 8 parts of silicon carbide fine powder, 9 parts of bauxite fine powder, 6 parts of tabular corundum fine powder, 2 parts of α-Al2O3 micro powder, 4 parts of lanthanum zirconate fine powder, and 4 parts of calcium aluminate cement as raw materials, add 0.2 parts of sodium tripolyphosphate to the above raw materials, mix evenly, then add 5 parts of water to the above raw materials, stir evenly, mold, cure for 3 days, demold, and bake to obtain energy-saving lightweight cement kiln inlet castable.

[0061] The energy-saving, lightweight cement kiln inlet castable prepared in this embodiment was tested and found to have an apparent porosity of 35% and a bulk density of 2.4 g / cm³. 3 The room temperature flexural strength at 110℃ for 24 hours is 6 MPa; the room temperature flexural strength at 1600℃ for 3 hours is 37 MPa; the thermal conductivity at 1200℃ is 1.1 W / (m·K); and the average emissivity in the 0.76~2.5μm band at room temperature is 69%.

[0062] Example 4.

[0063] Energy-saving lightweight cement kiln inlet castable and its preparation method:

[0064] The preparation method of alumina-lanthanum hexaaluminate composite fine powder is as follows: First, 6 parts of plate-shaped corundum fine powder, 2 parts of mullite micro powder, 3 parts of lanthanum aluminate fine powder, and 9 parts of dextrin are mixed and ball-milled for 7 hours to obtain ball-milled powder; then, 9 parts of water are added to the ball-milled powder, granulated, and pre-formed spheres with particle sizes of 5~3 mm, 3~1 mm, and 1~0 mm are obtained, and dried at 110℃ for 36 hours; then, the dried pre-formed spheres are calcined at 1250℃ for 7 hours, crushed, and ball-milled to obtain lightweight lanthanum aluminate-mullite aggregate.

[0065] Preparation method of energy-saving lightweight cement kiln inlet castable: First, use 62 parts of lightweight lanthanum aluminate-mullite aggregate, 8 parts of silicon carbide fine powder, 11 parts of high-grade bauxite fine powder, 5 parts of tabular corundum fine powder, 1 part of α-Al2O3 micro powder, 3 parts of lanthanum zirconate fine powder, and 5 parts of calcium aluminate cement as raw materials, add 0.2 parts of FS20 to the above raw materials, mix evenly, then add 6 parts of water to the above raw materials, stir evenly, mold, cure for 3 days, demold, and bake to obtain energy-saving lightweight cement kiln inlet castable.

[0066] The energy-saving, lightweight cement kiln inlet castable prepared in this embodiment was tested and found to have an apparent porosity of 33% and a bulk density of 2.5 g / cm³. 3 The room temperature flexural strength at 110℃ for 24 hours is 7 MPa; the room temperature flexural strength at 1600℃ for 3 hours is 40 MPa; the thermal conductivity at 1200℃ is 1.2 W / (m·K); and the average emissivity in the 0.76~2.5μm band at room temperature is 72%.

[0067] Comparative Example 1.

[0068] A cement kiln inlet castable and its preparation method: First, 60 parts of mullite lightweight aggregate, 5 parts of silicon carbide fine powder, 10 parts of bauxite fine powder, 6 parts of tabular corundum fine powder, 1 part of α-Al2O3 micro powder, 6 parts of lanthanum zirconate fine powder, and 6 parts of calcium aluminate cement are used as raw materials, and 0.2 parts of FS10 are added to the raw materials. After mixing evenly, 6 parts of water are added to the raw materials, stirred evenly, molded, cured for 2 days, demolded, and baked to obtain an energy-saving lightweight cement kiln inlet castable.

[0069] The energy-saving lightweight cement kiln inlet castable prepared in this comparative example was tested and found to have the following characteristics: apparent porosity of 18%; bulk density of 2.9 g / cm3; room temperature flexural strength of 10 MPa at 110℃ for 24 h; room temperature flexural strength of 50 MPa at 1600℃ for 3 h; thermal conductivity of 2.3 W / (m·K) at 1200℃; and average emissivity of 25% in the 0.76~2.5μm wavelength band at room temperature.

[0070] Comparative Example 2.

[0071] An energy-saving, lightweight cement kiln inlet castable and its preparation method:

[0072] The preparation method of lightweight lanthanum aluminate-mullite aggregate is as follows: 4 parts of fine mullite powder, 1 part of micro-mullite powder, 3 parts of fine lanthanum aluminate powder, and 4 parts of dextrin are mixed and ball-milled for 4 hours to obtain ball-milled powder; then 6 parts of water are added to the ball-milled powder, and granulation is performed to obtain pre-formed spheres with particle sizes of 5~3mm, 3~1mm, and 1~0mm, respectively, which are dried at 110℃ for 24 hours; then the dried pre-formed spheres are calcined at 1400℃ for 5 hours, crushed, ball-milled, and sieved to obtain lightweight lanthanum aluminate-mullite aggregate.

[0073] Preparation method of energy-saving lightweight cement kiln inlet castable: First, use 60 parts of lightweight lanthanum aluminate-mullite aggregate, 5 parts of silicon carbide fine powder, 10 parts of bauxite fine powder, 12 parts of tabular corundum fine powder, 1 part of α-Al2O3 micro powder, and 6 parts of calcium aluminate cement as raw materials, add 0.2 parts of FS10 to the above raw materials, mix evenly, then add 6 parts of water to the above raw materials, stir evenly, form, cure for 2 days, demold, and bake to obtain energy-saving lightweight cement kiln inlet castable.

[0074] The energy-saving, lightweight cement kiln inlet castable prepared in this comparative example was tested and found to have an apparent porosity of 28% and a bulk density of 2.7 g / cm³. 3 The room temperature flexural strength at 110℃ for 24 hours is 8 MPa; the room temperature flexural strength at 1600℃ for 3 hours is 42 MPa; the thermal conductivity at 1200℃ is 1.7 W / (m·K); and the average emissivity in the 0.76~2.5μm band at room temperature is 50%.

Claims

1. An energy-saving, lightweight cement kiln inlet castable, characterized in that, The composition includes the following components in parts by weight: 60-70 parts of light lanthanum aluminate-mullite aggregate, 5-10 parts of silicon carbide fine powder, 8-12 parts of bauxite fine powder, 4-8 parts of tabular corundum fine powder, 1-3 parts of α-Al2O3 micro powder, 1-6 parts of lanthanum zirconate fine powder, 4-6 parts of calcium aluminate cement, 0.1-0.2 parts of water-reducing agent, and 5-6 parts of water; Mix 4-12 parts of fine mullite powder, 1-3 parts of micro-mullite powder, 2-6 parts of fine lanthanum aluminate powder, and 4-12 parts of dextrin, and ball mill for 4-8 hours to obtain ball-milled powder; then add 6-10 parts of water to the ball-milled powder, granulate, and obtain pre-formed spherical aggregate, and dry at 110℃ for 24-36 hours; then calcine the dried spherical aggregate at 1200-1400℃, and sieve to obtain lightweight lanthanum aluminate-mullite aggregate.

2. The energy-saving lightweight cement kiln inlet castable according to claim 1, characterized in that, The particle size distribution of the light lanthanum aluminate-mullite aggregate is as follows: particles with a diameter of 3-5 mm account for 40-50 wt%, particles with a diameter of 1-3 mm account for 25-40 wt%, and particles with a diameter of 0.1-1 mm account for 10-25 wt%. The light lanthanum aluminate-mullite aggregate has a porosity ≥50%, an average pore size of 2-20 μm, and a lanthanum aluminate content ≥50 wt%.

3. The energy-saving lightweight cement kiln inlet castable according to claim 1, characterized in that, The silicon carbide fine powder has a particle size ≤0.088mm and a SiC content ≥90wt%; the bauxite fine powder has a particle size ≤0.088mm and an Al2O3 content ≥60wt%.

4. The energy-saving lightweight cement kiln inlet castable according to claim 1, characterized in that, The particle size of the tabular corundum fine powder is ≤0.088mm, and the Al2O3 content in the tabular corundum fine powder is ≥99wt%; the particle size of the α-Al2O3 micro powder is ≤2μm, and the Al2O3 content in the α-Al2O3 micro powder is ≥98wt%.

5. The energy-saving lightweight cement kiln inlet castable according to claim 1, characterized in that, The particle size of the lanthanum zirconate fine powder is ≤ 88μm, and the La2Zr2O7 content in the lanthanum zirconate fine powder is ≥99wt%.

6. The energy-saving lightweight cement kiln inlet castable according to claim 1, characterized in that, The Al2O3 content in the calcium aluminate cement is ≥71wt%.

7. The energy-saving lightweight cement kiln inlet castable according to claim 1, characterized in that, The water-reducing agent is one of sodium tripolyphosphate, sodium hexametaphosphate, FS10, or FS20.

8. A method for preparing an energy-saving lightweight cement kiln inlet castable according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: First, mix 4-12 parts of fine mullite powder, 1-3 parts of micro-mullite powder, 2-6 parts of fine lanthanum aluminate powder, and 4-12 parts of dextrin, and ball mill for 4-8 hours to obtain ball-milled powder; then add 6-10 parts of water to the ball-milled powder, granulate, and obtain pre-formed spherical aggregate, and dry it at 110℃ for 24-36 hours; then calcine the dried spherical aggregate under certain conditions, sieve, and obtain lightweight lanthanum aluminate-mullite aggregate; Step 2: First, use 60-70 parts of lightweight lanthanum aluminate-mullite aggregate, 5-10 parts of silicon carbide fine powder, 8-12 parts of bauxite fine powder, 4-8 parts of tabular corundum fine powder, 1-3 parts of α-Al2O3 micro powder, 1-6 parts of lanthanum zirconate fine powder, and 4-6 parts of calcium aluminate cement as raw materials, and add 0.1-0.2 parts of water-reducing agent to the above raw materials. Mix them evenly, then add 5-6 parts of water to the above raw materials, stir evenly, form, cure for 2-3 days, demold, and bake to obtain energy-saving lightweight cement kiln inlet castable.

9. The method for preparing an energy-saving lightweight cement kiln inlet castable according to claim 8, characterized in that, In step 1, the Al2O3 content in the fine mullite powder is ≤70wt%; the Al2O3 content in the micromullite powder is ≤70wt%.

10. The method for preparing an energy-saving lightweight cement kiln inlet castable according to claim 8, characterized in that, In step 1, the pre-formed spherical aggregate has a particle size of 5-3 mm, 3-1 mm, and 1-0 mm; the calcination temperature is 1200-1400℃, and the calcination time is 3-8 hours.

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