Calcium titan-aluminate refractory material using aluminum titanium slag as raw material and preparation method thereof

Abstract

The application relates to the technical field of materials, in particular to a calcium titan-aluminate refractory material taking aluminum-titanium slag as raw material and a preparation method thereof, which comprises aluminum-titanium slag, industrial alumina, modified zirconium-magnesium powder, modified lanthanum-yttrium powder, active alumina and boric acid. The modified zirconium-magnesium powder and the modified lanthanum-yttrium powder are used to resist fluorine ion erosion in cooperation, and the active alumina is used to enhance the fluorine resistance function of the modified powder, so that the fluorine resistance of the calcium titan-aluminate refractory material in a fluorine-rich refining slag environment is improved, and the service life of the calcium titan-aluminate refractory material is prolonged compared with conventional calcium titan-aluminate refractory materials.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a calcium aluminate refractory material made from aluminotitanium slag and its preparation method. Background Technology

[0002] Using alumina-titanium slag as the main raw material, the solid-state reaction sintering method is used to prepare calcium aluminate titanate refractories, which is an important way to utilize industrial solid waste and produce high-performance refractory products. In this process, inexpensive sodium-containing compounds (such as borax) are often added as fluxes to promote sintering. However, when such sodium-containing refractories are applied to the furnace lining and permeable bricks of ladle refining (especially LF furnace), the fluorite (CaF2) added during the refining process to optimize the desulfurization effect will react with sodium ions (Na+) in the material at high temperatures. + The reaction produces low-melting-point sodium fluoride (NaF), which washes away and dissolves the grain boundary phase of the refractory material, causing its structure to become rapidly loose, its high-temperature strength to drop sharply, and its service life to be shortened.

[0003] To address the problems caused by the reaction between sodium and fluorine, those skilled in the art employ sodium-free or low-sodium composite fluxes during the preparation stage to avoid rapid corrosion caused by sodium ions introduced into the material itself. However, the inventors discovered that even calcium aluminate titanate refractory materials prepared using non-sodium fluxes, when operating in LF furnaces for extended periods in a CaO-SiO2-Al2O3-based refining slag environment rich in fluorite, exhibited a relatively rapid rate of degradation, though this was mitigated. Further investigation revealed that fluoride ions (F...) in the refining slag... - It has extremely strong penetrability and reactivity, and can directly attack and destroy the silicate and other bonded phases at the grain boundaries of refractory materials. By forming volatile SiF4 or low-melting-point fluorosilicate intermediates, it gradually depolymerizes the grain boundary network, which ultimately leads to the weakening and peeling of the material structure. Summary of the Invention

[0004] (1) Technical problems to be solved

[0005] The purpose of this invention is to provide a calcium aluminate refractory material made from alumina-titanium slag and its preparation method, so as to solve the problem of fluoride ions in the refining slag damaging the refractory material during LF furnace service.

[0006] (2) Technical solution

[0007] To achieve the above objectives, on the one hand, the present invention provides a calcium aluminate refractory material made from alumina-titanium slag, comprising the following weight parts: 900-1100 parts of alumina-titanium slag, 50-150 parts of industrial alumina, 35-50 parts of modified zirconium-magnesium powder, 25-40 parts of modified lanthanum-yttrium powder, 6-9 parts of activated alumina, and 8-15 parts of boric acid;

[0008] The modified zirconium-magnesium powder is a composite powder obtained by ball milling and calcining zirconium oxide, calcium carbonate, magnesium oxide and aluminum oxide; the modified lanthanum-yttrium powder is a composite powder obtained by ball milling and calcining lanthanum oxide, yttrium oxide and aluminum oxide.

[0009] The amount of activated alumina used is 8%-12% of the total mass of modified zirconium magnesium powder and modified lanthanum yttrium powder.

[0010] Furthermore, the aluminum-titanium slag is a metallurgical waste slag powder containing Al2O3, TiO2 and CaO, with Al2O3 content ≥65%, TiO2 content ≥8%, and CaO content ≤15% by mass percentage.

[0011] Furthermore, the industrial alumina is α-Al2O3 powder with a particle size D50 of 1-10 μm.

[0012] Furthermore, the activated alumina is γ-Al₂O₃ powder with a specific surface area ≥200 m². 2 / g, particle size D50 is 20-50nm, purity ≥99.5%.

[0013] Furthermore, the boric acid is of analytical grade with a purity ≥99.5%.

[0014] Furthermore, the preparation method of the modified zirconium magnesium powder includes the following steps:

[0015] S11. Weigh zirconium oxide, calcium carbonate, magnesium oxide, and aluminum oxide and place them in a polytetrafluoroethylene ball mill jar. Add grinding balls and anhydrous ethanol, ball mill, and separate to obtain slurry A.

[0016] S12. Rotary evaporate slurry A until the ethanol is completely removed, transfer it to a high-purity alumina crucible, place it in a high-temperature muffle furnace, heat it to 500℃ and hold it, continue to heat it to 1200℃ and hold it, let it cool naturally to room temperature with the furnace, take it out, grind it and sieve it, collect the powder under the sieve to obtain modified zirconium magnesium powder.

[0017] Furthermore, the preparation method of the modified lanthanum yttrium powder includes the following steps:

[0018] S21. After calcining lanthanum oxide, weigh it immediately for use. Weigh lanthanum oxide, yttrium oxide, and aluminum oxide separately and place them in a polytetrafluoroethylene ball mill jar. Add grinding balls and anhydrous ethanol, ball mill, and separate to obtain slurry B.

[0019] S22. The slurry B is rotary evaporated to dryness, placed in a high-purity alumina crucible, placed in a muffle furnace, heated to 500℃ and held, then heated to 1150℃ and held, cooled to room temperature with the furnace, removed, ground and sieved, and immediately sealed and stored in a desiccator to obtain modified lanthanum yttrium powder.

[0020] On the other hand, the present invention also provides a method for preparing calcium aluminate titanate refractory material using aluminotitanium slag as raw material, comprising the following steps:

[0021] S1. Preparation of mixture: Modified zirconium magnesium powder, modified lanthanum yttrium powder, activated alumina, and boric acid are placed in a high-speed mixer and premixed for 10 minutes to obtain a premix; the premix, alumina slag, and industrial alumina are added to the mixer and dry-mixed for 20 minutes, then calcium aluminate cement and water are added and wet-mixed for 15 minutes until the material is uniform and plastic.

[0022] S2. Molding and drying: The mixture is filled into a steel mold and pressed into shape on a hydraulic press. After the molded blank is demolded, it is transferred to a forced-air drying oven. The temperature is set at 60℃ and dried for 12 hours. Then the temperature is raised to 110℃ and dried for another 12 hours to obtain a dried blank.

[0023] S3. Sintering preparation of refractory materials: The dried green body was placed in a high-temperature kiln for sintering. The sintering procedure was as follows: the first stage was to raise the temperature from room temperature to 300℃ at a rate of 2℃ / min and hold for 1 hour; the second stage was to raise the temperature to 600℃ at a rate of 2℃ / min and hold for 1 hour; the third stage was to raise the temperature to 1100℃ at a rate of 2℃ / min and hold for 1 hour; the fourth stage was to raise the temperature to 1250℃ at a rate of 1.5℃ / min and hold for 2 hours; the fifth stage was to raise the temperature to 1480℃ at a rate of 1℃ / min and hold for 4 hours. After the holding period, the temperature was lowered to 1000℃ at a rate of 2℃ / min. Then the heating power was turned off and the furnace was allowed to cool naturally to room temperature to obtain a calcium aluminate titanate refractory material made from aluminotitanium slag.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. In this invention, modified zirconium-magnesium powder and modified lanthanum-yttrium powder work together to resist fluoride ion corrosion. The modified zirconium-magnesium powder forms a high-melting-point skeleton structure in the grain boundary region to achieve physical barrier, while the modified lanthanum-yttrium powder converts fluoride ions into stable high-melting-point solid products to achieve chemical fixation. At the same time, the two types of powders combine to form a complete anti-corrosion system during sintering, which improves the material's corrosion resistance in fluoride-rich refining slag environment and extends its service life compared to conventional calcium titanate aluminate refractory materials.

[0026] 2. In this invention, the activated alumina enhances the synergistic anti-fluoride function of the modified powder. By supplementing and generating a target phase with anti-fluoride function, the overall fluoride capture capacity of the material is increased. At the same time, it enhances the interfacial bonding strength between the modified powders, thereby further enhancing the material's resistance to slag erosion and service life. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the preparation process of calcium aluminate titanate refractory material using aluminotitanium slag as raw material, as described in Embodiment 1 of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: This example discloses a calcium aluminate refractory material made from aluminum-titanium slag, comprising the following parts by weight: 1000 parts aluminum-titanium slag, 100 parts industrial alumina, 43 parts modified zirconium magnesium powder, 32 parts modified lanthanum yttrium powder, 7.5 parts activated alumina, and 12 parts boric acid.

[0030] The modified zirconium-magnesium powder is a composite powder obtained by ball milling and calcining zirconium oxide, calcium carbonate, magnesium oxide and aluminum oxide; the modified lanthanum-yttrium powder is a composite powder obtained by ball milling and calcining lanthanum oxide, yttrium oxide and aluminum oxide.

[0031] The amount of activated alumina used is 10% of the total mass of modified zirconium magnesium powder and modified lanthanum yttrium powder.

[0032] The aluminum-titanium slag is a metallurgical waste slag powder containing Al2O3, TiO2 and CaO. By mass percentage, the Al2O3 content is ≥65%, the TiO2 content is ≥8%, and the CaO content is ≤15%.

[0033] The industrial alumina is α-Al2O3 powder with a particle size D50 of 1-10 μm.

[0034] The activated alumina is γ-Al₂O₃ powder with a specific surface area ≥200m². 2 / g, particle size D50 is 20-50nm, purity ≥99.5%.

[0035] The boric acid is of analytical grade with a purity of ≥99.5%.

[0036] The preparation method of the modified zirconium magnesium powder includes the following steps:

[0037] S11. Weigh 55.0g zirconium oxide, 20.0g calcium carbonate, 10.0g magnesium oxide, and 15.0g aluminum oxide, place them in a 500mL polytetrafluoroethylene ball mill jar, add 400g zirconium oxide grinding balls and 200mL anhydrous ethanol, install the ball mill jar on a planetary ball mill, set the revolution speed to 300r / min, and the ball milling time to 4h. Pause for 10min every 30min to prevent overheating. After the ball milling is completed, separate to obtain slurry A.

[0038] S12. Transfer slurry A to a rotary evaporator, set the water bath temperature to 60℃ and the vacuum degree to 0.08MPa, evaporate until the ethanol is completely removed, transfer it to a 100mL high-purity alumina crucible, place it in a high-temperature muffle furnace, heat it to 500℃ at a rate of 3℃ / min and hold it for 30min, continue to heat it to 1200℃ at a rate of 3℃ / min and hold it for 2h, after the holding time is over, let it cool naturally to room temperature with the furnace, take it out, grind it thoroughly in an agate mortar and pass it through a 100-mesh standard sieve, collect the powder under the sieve, and obtain modified zirconium magnesium powder.

[0039] The method for preparing the modified lanthanum-yttrium powder includes the following steps:

[0040] S21. Lanthanum oxide was calcined at 800℃ for 1 hour to remove adsorbed water and carbonates. Immediately after calcination, it was weighed and used. 35.0 g of lanthanum oxide, 18.0 g of yttrium oxide, and 47.0 g of aluminum oxide were weighed and placed in a 500 mL polytetrafluoroethylene ball mill jar. 400 g of zirconium oxide grinding balls and 200 mL of anhydrous ethanol were added. The mixture was ball milled at 300 r / min for 4 hours to separate and obtain slurry B.

[0041] S22. The slurry B was dried by rotary evaporation at 60℃, placed in a high-purity alumina crucible, and placed in a muffle furnace. The temperature was increased to 500℃ at a rate of 3℃ / min and held for 30 min. The temperature was then increased to 1150℃ at a rate of 3℃ / min and held for 3 h. The mixture was cooled to room temperature in the furnace, removed, ground through a 200-mesh standard sieve, and immediately sealed and stored in a desiccator to obtain modified lanthanum-yttrium powder.

[0042] The method for preparing calcium aluminate titanate refractory material using aluminotitanium slag as raw material includes the following steps:

[0043] S1. Preparation of the mixture: Modified zirconium magnesium powder, modified lanthanum yttrium powder, activated alumina, and boric acid are placed in a high-speed mixer and premixed at 800 r / min for 10 min to obtain a uniformly dispersed premix; the premix, alumina slag, and industrial alumina powder are added to the mixer and dry-mixed at 600 r / min for 20 min, then calcium aluminate cement and water are added, and wet-mixed for 15 min until the material is uniform and plastic.

[0044] S2. Molding and Drying: The mixture is filled into a steel mold and pressed into shape on a hydraulic press with a pressure of 100-150MPa. The pressure holding time is 30s. After the molded blank is demolded, it is transferred to a forced-air drying oven. The temperature is set to 60℃ and dried for 12 hours. Then the temperature is raised to 110℃ and dried for another 12 hours to ensure that the residual moisture of the blank is less than 0.5% by mass, thus obtaining a dried blank.

[0045] S3. Sintering Preparation of Refractory Materials: The dried green body was placed in a high-temperature kiln for sintering. The sintering procedure was as follows: First stage: temperature was increased from room temperature to 300℃ at a rate of 2℃ / min and held for 1 hour; Second stage: temperature was increased to 600℃ at a rate of 2℃ / min and held for 1 hour; Third stage: temperature was increased to 1100℃ at a rate of 2℃ / min and held for 1 hour; Fourth stage: temperature was increased to 1250℃ at a rate of 1.5℃ / min and held for 2 hours; Fifth stage: temperature was increased to 1480℃ at a rate of 1℃ / min and held for 4 hours. After the holding period, the temperature was decreased to 1000℃ at a rate of 2℃ / min, and then the heating power was turned off and the furnace was allowed to cool naturally to room temperature, yielding a calcium aluminate titanate refractory material made from aluminotitanium slag. The preparation process is as follows: Figure 1 As shown.

[0046] It should be noted that the modified zirconium magnesium powder and the modified lanthanum yttrium powder form an interface bond through oxygen bridges during the sintering process.

[0047] Example 2: This example is based on Example 1, but differs from Example 1 in that it includes the following weight proportions: 900 parts aluminum-titanium slag, 50 parts industrial alumina, 35 parts modified zirconium-magnesium powder, 25 parts modified lanthanum-yttrium powder, 6 parts activated alumina, and 8 parts boric acid.

[0048] The amount of activated alumina used is 10% of the total mass of modified zirconium magnesium powder and modified lanthanum yttrium powder.

[0049] The other components and preparation methods are the same as in Example 1.

[0050] Example 3: This example is based on Example 1, but differs from Example 1 in that it includes the following weight proportions: 1100 parts aluminum-titanium slag, 150 parts industrial alumina, 50 parts modified zirconium-magnesium powder, 40 parts modified lanthanum-yttrium powder, 9 parts activated alumina, and 15 parts boric acid.

[0051] The amount of activated alumina used is 10% of the total mass of modified zirconium magnesium powder and modified lanthanum yttrium powder.

[0052] The other components and preparation methods are the same as in Example 1.

[0053] Example 4: This example is based on Example 1, but differs from Example 1 in that it includes the following weight proportions: 1000 parts aluminum-titanium slag, 100 parts industrial alumina, 43 parts modified zirconium-magnesium powder, 32 parts modified lanthanum-yttrium powder, 6 parts activated alumina, and 12 parts boric acid.

[0054] The amount of activated alumina used is 8% of the total mass of the modified zirconium magnesium powder and the modified lanthanum yttrium powder.

[0055] The other components and preparation methods are the same as in Example 1.

[0056] Example 5: This example is based on Example 1, but differs from Example 1 in that it includes the following weight proportions: 1000 parts aluminum-titanium slag, 100 parts industrial alumina, 43 parts modified zirconium-magnesium powder, 32 parts modified lanthanum-yttrium powder, 9 parts activated alumina, and 12 parts boric acid.

[0057] The amount of activated alumina used is 12% of the total mass of modified zirconium magnesium powder and modified lanthanum yttrium powder.

[0058] The other components and preparation methods are the same as in Example 1.

[0059] Comparative Example 1: This comparative example is based on Example 1, except that unmodified zirconium oxide powder is used instead of modified zirconium magnesium powder. Other components and preparation methods are the same as in Example 1.

[0060] Comparative Example 2: This comparative example is based on Example 1, except that unmodified lanthanum oxide powder is used instead of modified lanthanum yttrium powder. Other components and preparation methods are the same as in Example 1.

[0061] Comparative Example 3: This comparative example is based on Example 1, but differs from Example 1 in that it uses a powder of zirconium oxide, calcium carbonate, magnesium oxide and aluminum oxide mixed in the same proportion in a simple physical manner to replace the modified zirconium magnesium powder. It is not subjected to ball milling and calcination treatment. Other components and preparation methods are the same as in Example 1.

[0062] Comparative Example 4: This comparative example is based on Example 1, but differs from Example 1 in that it uses a powder made by simply physically mixing lanthanum oxide, yttrium oxide, and aluminum oxide in the same proportions instead of modified lanthanum-yttrium powder. It is not subjected to ball milling or calcination treatment, and the other components and preparation methods are the same as in Example 1.

[0063] Comparative Example 5: This comparative example is based on Example 1, but differs from Example 1 in that the amount of activated alumina used in this comparative example is reduced to 6% of the total mass of the modified powder, while the other components and preparation methods are the same as in Example 1.

[0064] Comparative Example 6: This comparative example is based on Example 1, but differs from Example 1 in that the amount of activated alumina used in this comparative example is increased to 15% of the total mass of the modified powder. Other components and preparation methods are the same as in Example 1.

[0065] Comparative Example 7: This comparative example is based on Example 1, but differs from Example 1 in that it does not include modified zirconium magnesium powder.

[0066] Comparative Example 8: This comparative example is based on Example 1, but differs from Example 1 in that it does not include modified lanthanum yttrium powder.

[0067] Comparative Example 9: This comparative example is based on Example 1, but differs from Example 1 in that it does not include modified zirconium magnesium powder and modified lanthanum yttrium powder.

[0068] Comparative Example 10: This comparative example is based on Example 1, but unlike Example 1, it does not include activated alumina.

[0069] Comparative Example 11: This comparative example is a blank control group, which consists of 1000 parts of aluminum-titanium slag, 100 parts of industrial alumina, and 12 parts of boric acid to prepare ordinary calcium titanate refractory material.

[0070] Experimental verification:

[0071] Experiment 1: Verify the fluorine corrosion resistance of the calcium aluminate titanate refractory materials prepared in Examples 1-5 and Comparative Examples 1-11. The results are shown in Table 1.

[0072] The detection indicators and methods are as follows:

[0073] Erosion depth test: Mixtures were prepared according to each formula, filled into crucible molds with an outer diameter of 80 mm, an inner diameter of 40 mm, and a height of 80 mm, and pressed into shape. After drying and sintering, crucible samples were obtained, with 3 samples prepared in parallel for each group. The static crucible method was used for testing according to GB / T 8931-2007. The simulated LF furnace fluorine-rich refining slag (CaO 45%, SiO2 15%, Al2O3 25%, MgO 8%, CaF2 7%) was loaded into the inner cavity of the crucible sample, kept at 1600℃ for 4 h, and then cooled with the furnace. The crucible was longitudinally cut open to measure the maximum vertical distance from the inner wall to the erosion interface.

[0074] Fluorine ion diffusion depth test: Mixtures were prepared according to each formulation, filled into cylindrical molds with a diameter of 50 mm and a height of 30 mm, and pressed into shape. After drying and sintering, the upper and lower end faces were cut and polished flat to obtain circular samples. Three samples were prepared in parallel for each group. One side of the circular sample was contacted with slag containing 10% CaF2, and the sample was kept at 1500℃ for 6 hours and then cooled. The sample was cut open along the direction perpendicular to the contact surface, and the cross-section was analyzed by line scanning using electron probe microanalysis (EPMA). The depth at which the fluorine concentration drops to 10% of the concentration at the contact surface was taken as the effective diffusion depth.

[0075] Fluoride ion curing rate test: Take the sintered block samples from each group, crush them, ball mill them, and pass them through a 200-mesh sieve to obtain powder samples. Prepare no less than 50g of powder samples for each group. Mix the powder samples with synthetic slag containing 5% CaF2 at a mass ratio of 1:1. After holding at 1500℃ for 2h, quickly cool them. Use the fluoride ion selective electrode method to determine the residual fluoride ion concentration after the reaction. Calculate the curing rate according to the formula: Fluoride curing rate (%) = (C0-C) / C0×100%, where C0 is the initial fluoride ion concentration and C is the residual fluoride ion concentration after the reaction. Each group is measured in parallel 3 times.

[0076] Relative service life test: Mixtures were prepared according to each formula, filled into cylindrical molds with a diameter of 20 mm and a height of 120 mm, and pressed into shape. After drying and sintering, cylindrical samples were obtained. Three samples were prepared in parallel for each group. The dynamic rotational erosion method was used for evaluation. The cylindrical samples were immersed in a refining slag molten pool at 1550℃ (slag composition is the same as the erosion depth test) and rotated at a speed of 8 r / min until the sample diameter loss reached 50%. The erosion time was recorded. The relative service life of each sample was calculated with the erosion time of Comparative Example 11 as the baseline of 1.0.

[0077]

[0078] Based on the data in Table 1, it can be concluded that the present invention improves the resistance to fluorine corrosion of the material in a fluorine-rich refining slag environment by modifying zirconium magnesium powder, modifying lanthanum yttrium powder, and activated alumina, and extends the service life of the material compared with conventional calcium titanate refractory materials.

[0079] Experiment 2: Verify the basic properties of the calcium aluminate titanate refractory materials prepared in Examples 1-5. The results are shown in Table 2.

[0080] The detection indicators and methods are as follows:

[0081] Bulk density and apparent porosity tests: Mixtures were prepared according to each formulation, filled into square molds with dimensions of 50mm x 50mm x 50mm, and pressed into shape. After drying and sintering, block samples were obtained, with three samples prepared in parallel for each group. The bulk density (g / cm³) of the samples was determined by boiling method according to GB / T2997-2015. 3 The apparent porosity (%) is calculated using the following formulas: bulk density ρb = m1 / (m3-m2) × ρliquid, apparent porosity Pa = (m3-m1) / (m3-m2) × 100%, where m1 is the dry mass, m2 is the suspended mass, m3 is the saturated mass, and ρliquid is the density of the immersion liquid.

[0082] Room temperature compressive strength test: Prepare mixtures according to each formula, fill them into cylindrical molds with a diameter of 50 mm and a height of 50 mm, press them into shape, and after drying and sintering, cut and grind the upper and lower end faces to obtain cylindrical specimens. Prepare 5 parallel specimens for each group. According to GB / T 5072-2008, use a universal testing machine to conduct uniaxial compression tests on the specimens at a loading rate of 0.5 MPa / s. Record the maximum load when the specimen fails, and calculate the room temperature compressive strength according to the formula: σc=P / A, where P is the maximum load (N) and A is the pressure area (mm²).

[0083] High-temperature flexural strength test: Mixtures were prepared according to each formula, filled into strip molds with length × width × height of 150mm × 25mm × 25mm, and pressed into shape. After drying and sintering, strip specimens were obtained, and three were prepared in parallel for each group. According to GB / T 3002-2017, the specimens were placed in a high-temperature furnace and heated to 1400℃ and held for 30min. The three-point bending method was used for testing, with a span of 125mm and a loading rate of 0.15MPa / s. The high-temperature flexural strength was calculated according to the formula: σf=3PL / (2bh²), where P is the breaking load (N), L is the span (mm), b is the specimen width (mm), and h is the specimen height (mm).

[0084] Thermal shock resistance test: Mixtures were prepared according to each formula, filled into strip molds with length × width × height of 150mm × 25mm × 25mm, pressed into shape, dried and sintered to obtain strip specimens, and three were prepared in parallel for each group; according to YB / T 376.2-1995, the air rapid cooling method was used for testing: the specimens were placed in a high-temperature furnace at 1100℃ for 15min and then taken out and cooled in flowing air at room temperature for 10min. This cycle was repeated, and the number of thermal shocks when the specimens showed visible cracks or peeling was used as the thermal shock resistance index; at the same time, the residual flexural strength of the specimens after 3 thermal shock cycles was measured, and the strength retention rate (%) was calculated as σ3 / σ0 × 100%, where σ0 is the flexural strength before thermal shock and σ3 is the flexural strength after 3 thermal shocks.

[0085]

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A calcium aluminate refractory material using aluminotitanium slag as raw material, characterized in that, The composition includes the following components by weight: 900-1100 parts aluminum-titanium slag, 50-150 parts industrial alumina, 35-50 parts modified zirconium-magnesium powder, 25-40 parts modified lanthanum-yttrium powder, 6-9 parts activated alumina, and 8-15 parts boric acid. The modified zirconium-magnesium powder is a composite powder obtained by ball milling and calcining zirconium oxide, calcium carbonate, magnesium oxide and aluminum oxide; the modified lanthanum-yttrium powder is a composite powder obtained by ball milling and calcining lanthanum oxide, yttrium oxide and aluminum oxide. The amount of activated alumina used is 8%-12% of the total mass of modified zirconium magnesium powder and modified lanthanum yttrium powder; The preparation method of the modified zirconium magnesium powder includes the following steps: S11. Weigh zirconium oxide, calcium carbonate, magnesium oxide, and aluminum oxide and place them in a polytetrafluoroethylene ball mill jar. Add grinding balls and anhydrous ethanol, ball mill, and separate to obtain slurry A. S12. Rotary evaporate slurry A until the ethanol is completely removed, transfer it to a high-purity alumina crucible, place it in a high-temperature muffle furnace, heat it to 500°C and hold it, continue to heat it to 1200°C and hold it, let it cool naturally to room temperature with the furnace, take it out, grind it and sieve it, collect the powder under the sieve to obtain modified zirconium magnesium powder. The method for preparing the modified lanthanum-yttrium powder includes the following steps: S21. After calcining lanthanum oxide, weigh it immediately before use. Weigh lanthanum oxide, yttrium oxide, and aluminum oxide separately and place them in a polytetrafluoroethylene ball mill jar. Add grinding balls and anhydrous ethanol, ball mill, and separate to obtain slurry B. S22. The slurry B is rotary evaporated to dryness, placed in a high-purity alumina crucible, placed in a muffle furnace, heated to 500℃ and held, then heated to 1150℃ and held, cooled to room temperature with the furnace, removed, ground and sieved, and immediately sealed and stored in a desiccator to obtain modified lanthanum yttrium powder.

2. The calcium aluminate titanate refractory material based on aluminotitanium slag as described in claim 1, characterized in that, The aluminum-titanium slag is a metallurgical waste slag powder containing Al2O3, TiO2 and CaO. By mass percentage, the Al2O3 content is ≥65%, the TiO2 content is ≥8%, and the CaO content is ≤15%.

3. The calcium aluminate titanate refractory material based on aluminotitanium slag as described in claim 1, characterized in that, The industrial alumina is α-Al2O3 powder with a particle size D50 of 1-10 μm.

4. The calcium aluminate titanate refractory material based on aluminotitanium slag as described in claim 1, characterized in that, The activated alumina is γ-Al₂O₃ powder with a specific surface area ≥200m². 2 / g, particle size D50 is 20-50nm, purity ≥99.5%.

5. The calcium aluminate titanate refractory material based on aluminotitanium slag as described in claim 1, characterized in that, The boric acid is of analytical grade with a purity of ≥99.5%.

6. A method for preparing calcium aluminate titanate refractory material using aluminotitanium slag as raw material according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of mixture: Modified zirconium magnesium powder, modified lanthanum yttrium powder, activated alumina, and boric acid are placed in a high-speed mixer and premixed for 10 minutes to obtain a premix; the premix, alumina slag, and industrial alumina are added to the mixer and dry-mixed for 20 minutes, then calcium aluminate cement and water are added and wet-mixed for 15 minutes until the material is uniform and plastic. S2. Molding and drying: The mixture is filled into a steel mold and pressed into shape on a hydraulic press. After the molded blank is demolded, it is transferred to a forced-air drying oven. The temperature is set at 60℃ and dried for 12 hours. Then the temperature is raised to 110℃ and dried for another 12 hours to obtain a dried blank. S3. Sintering preparation of refractory materials: The dried green body is placed in a high-temperature kiln for sintering. The sintering procedure is as follows: the first stage is to raise the temperature from room temperature to 300℃ at a rate of 2℃ / min and hold for 1 hour; the second stage is to raise the temperature to 600℃ at a rate of 2℃ / min and hold for 1 hour; the third stage is to raise the temperature to 1100℃ at a rate of 2℃ / min and hold for 1 hour; the fourth stage is to raise the temperature to 1250℃ at a rate of 1.5℃ / min and hold for 2 hours. In the fifth stage, the temperature was raised to 1480℃ at a rate of 1℃ / min and held for 4 hours. After the holding period, the temperature was lowered to 1000℃ at a rate of 2℃ / min. Then the heating power was turned off and the furnace was allowed to cool naturally to room temperature, resulting in a calcium aluminate refractory material made from aluminotitanium slag.

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