Inorganic castable and production process

Abstract

The invention discloses an inorganic castable and a production process, and relates to the technical field of high-temperature industry, and the inorganic castable is prepared from the following raw materials in parts by mass: 40-60 parts of high-aluminum aggregate, 15-30 parts of corundum fine powder, 5-15 parts of silica powder, 5-10 parts of calcium aluminate cement and the like. The proportion of high-purity raw materials such as the high-aluminum aggregate and the corundum fine powder is reasonably adjusted, and functional materials such as nano titanium dioxide and silicon carbide are introduced, so that the castable is endowed with excellent performance. According to the castable, the compressive strength at the temperature of 1400 DEG C is larger than or equal to 80 MPa, the strength retention rate is larger than or equal to 85% after 15 times of water-cooled thermal shock cycles at the temperature of 1100 DEG C, the thickness of an erosion layer formed at the temperature of 1400 DEG C is reduced by more than 50% compared with that of a traditional castable, the castable is outstanding in the aspects of high-temperature strength, thermal shock resistance and erosion resistance, and the strict requirements of the high-temperature industrial field for material performance can be effectively met.

Description

Technical Field

[0001] This invention relates to the field of high-temperature industrial technology, and in particular to an inorganic castable and its production process. Background Technology

[0002] Inorganic castables, as indispensable key materials in high-temperature industrial fields, play important roles in equipment such as blast furnace and converter linings in the metallurgical industry, cement rotary kilns and glass melting furnaces in the building materials industry, and high-temperature reactors in the chemical industry. Their performance directly affects the operational stability and service life of the equipment. With the rapid development of modern high-temperature industries towards larger scale, higher efficiency, and energy conservation, more stringent requirements are being placed on the comprehensive performance of inorganic castables.

[0003] Currently, the traditional inorganic castables widely used in the market are mainly represented by ordinary high-alumina castables and low-cement-binder castables. These traditional castables have revealed many insurmountable problems in actual use. In terms of performance, insufficient high-temperature strength makes the castables prone to structural deformation and collapse in high-temperature environments, affecting the normal operation of equipment; poor thermal shock resistance causes significant internal thermal stress when the temperature changes rapidly, leading to crack propagation and even spalling, shortening service life; weak corrosion resistance makes them unable to withstand the erosion of high-temperature molten slag and corrosive gases, resulting in rapid material loss. For example, in steelmaking converters in the metallurgical industry, traditional castables, due to their poor corrosion resistance, require frequent repairs or replacements, increasing maintenance costs and reducing production efficiency.

[0004] In conclusion, developing a castable with excellent high-temperature strength, thermal shock resistance, and corrosion resistance has become the key to solving the current bottlenecks in high-temperature industrial development and promoting technological progress in the industry. Summary of the Invention

[0005] To address the technical problems existing in the background art, the present invention proposes an inorganic castable and its production process.

[0006] The present invention proposes an inorganic castable, which, by weight, comprises: 40-60 parts high-alumina aggregate, 15-30 parts fine corundum powder, 5-15 parts silica powder, 5-10 parts calcium aluminate cement, 3-8 parts silicon carbide, 0.5-2 parts sodium hexametaphosphate, 0.3-1.5 parts calcium lignosulfonate, 1-5 parts nano titanium dioxide, and 0.2-1 parts additives.

[0007] Furthermore, the high-alumina aggregate has an alumina content of ≥85% and a particle size of 1-5mm;

[0008] The alumina content of the corundum fine powder is ≥95%, and the particle size is ≤0.088mm;

[0009] The silica content of the silica powder is ≥92%, and the average particle size is 0.1-0.2μm.

[0010] Calcium aluminate cement is pure calcium aluminate cement with an alumina content of ≥70%;

[0011] Silicon carbide purity ≥90%, particle size ≤0.1mm;

[0012] Sodium hexametaphosphate is industrial grade with a purity of ≥95%.

[0013] Calcium lignosulfonate is of industrial grade with a purity ≥85%.

[0014] The average particle size of nano-titanium dioxide is 20-50 nm.

[0015] Furthermore,

[0016] The high-alumina aggregate has an alumina content of 88-90% and a particle size of 2-4 mm;

[0017] The alumina content of the fine corundum powder is 96-97%, and the particle size is 0.044-0.088 mm.

[0018] The silica content of the silica powder is 93-94%, and the average particle size is 0.12-0.18 μm;

[0019] The alumina content of calcium aluminate cement is 72-75%;

[0020] The purity of silicon carbide is 92-95%, and the particle size is 0.05-0.1 mm.

[0021] Furthermore, the additives are one or more mixtures of yttrium oxide and zirconium oxide, including but not limited to.

[0022] Furthermore, the additive is a mixture of yttrium oxide and zirconium oxide, and the mass ratio of yttrium oxide to zirconium oxide is 1:1-2:1.

[0023] The production process of the above-mentioned inorganic castable includes the following steps:

[0024] S1. High-alumina aggregate, corundum fine powder, silica powder, and silicon carbide are screened and impurity removed respectively. Calcium aluminate cement, sodium hexametaphosphate, calcium lignosulfonate, nano titanium dioxide, and additives are ground respectively.

[0025] S2. Weigh each component raw material according to the mass fraction. First, add high alumina aggregate, corundum fine powder, silicon micro powder, and silicon carbide into a forced mixer and mix for 3-5 minutes. Then add calcium aluminate cement, sodium hexametaphosphate, calcium lignosulfonate, nano titanium dioxide, and additives and continue mixing for 5-8 minutes to obtain dry mix.

[0026] S3. Add 8-12% water by weight of the dry mixture to the dry mixture and stir for 3-5 minutes to obtain a wet mixture.

[0027] S4. Aging the wet material for 2-4 hours at a temperature of 20-30℃ and a relative humidity of 60-80%;

[0028] S5. Pour the aged wet material into the mold and use vibration molding or tamping molding. The vibration frequency is 30-50Hz and the vibration time is 3-5 minutes, or the tamping force is uniform and moderate.

[0029] S6. Curing the molded casting material at a temperature of 20-30℃ and a relative humidity of ≥90% for 24-48 hours, and then drying it at a temperature of 100-150℃ for 2-4 hours.

[0030] S7. After drying, the castable material undergoes quality inspection and is packaged after passing the inspection.

[0031] Furthermore, the raw material screening and impurity removal are carried out using a combination of vibrating screens and magnetic separation equipment, with the vibrating screen having a mesh size of 40-80 mesh.

[0032] Furthermore, after grinding, the particle size of calcium aluminate cement, sodium hexametaphosphate, calcium lignosulfonate, 8-nanometer titanium dioxide, and additives is ≤0.044mm.

[0033] Furthermore, the mixing speed of the forced mixer is 80-120 r / min.

[0034] Furthermore, during the aging process, the wet material is turned over every hour.

[0035] The beneficial effects of this invention are:

[0036] 1. High-quality raw materials such as high-alumina aggregate and corundum powder are selected and their proportions are scientifically adjusted. Functional materials such as nano-titanium dioxide are also introduced. The high alumina content in the high-alumina aggregate and corundum powder forms a stable corundum phase framework at high temperatures, providing basic strength for the material. Nano-titanium dioxide, with its nano-size effect, can uniformly fill the pores inside the castable, refining the grain structure, effectively eliminating microscopic defects, and greatly improving the material's density. Through the synergistic effect of these multiple factors, the compressive strength of this inorganic castable can reach over 80 MPa at 1400℃, an improvement of over 20% compared to traditional castables. This effectively ensures the stability of the lining structure of high-temperature industrial equipment and reduces the risk of deformation and collapse.

[0037] 2. The addition of silicon carbide is a key factor in improving thermal shock resistance. Silicon carbide has high thermal conductivity and a low coefficient of thermal expansion, enabling it to rapidly conduct heat during rapid temperature changes, effectively reducing the internal thermal stress gradient of the material. Calcium lignosulfonate and sodium hexametaphosphate, as additives, optimize the microstructure of the castable, enhance the bonding force between particles, and inhibit crack initiation and propagation. Testing shows that after 15 cycles of water-cooled thermal shock at 1100℃, the strength retention rate of the castable of this invention is ≥85%, far exceeding the 70%-75% level of traditional castables, significantly improving the service life of the castable under fluctuating temperature environments.

[0038] 3. Under high-temperature conditions, high-purity high-alumina aggregate, corundum fine powder, and silicon carbide undergo a series of complex physicochemical reactions, forming a dense and continuous corrosion-resistant layer on the material surface. This corrosion-resistant layer acts as a robust barrier, effectively preventing the penetration and erosion of high-temperature molten slag and corrosive gases. In practical application simulation tests, the corrosion layer thickness of the castable of this invention is reduced by more than 50% compared to traditional castables, significantly improving the material's durability in harsh corrosive environments, reducing equipment maintenance frequency, and lowering maintenance costs. Detailed Implementation

[0039] Example 1

[0040] The present invention proposes an inorganic castable and its production process, which is implemented by the following technical solution:

[0041] A. Raw material proportions of inorganic castables

[0042] By weight, it includes: 40 parts high-alumina aggregate (alumina content 88%, particle size 2mm), 15 parts corundum fine powder (alumina content 96%, particle size 0.044mm), 5 parts silica powder (silica content 93%, average particle size 0.12μm), 5 parts calcium aluminate cement (alumina content 72%), 3 parts silicon carbide (purity 92%, particle size 0.05mm), 0.5 parts sodium hexametaphosphate (purity 95%), 0.3 parts calcium lignosulfonate (purity 85%), 1 part nano titanium dioxide (average particle size 20nm), and 0.2 parts additive (yttrium oxide).

[0043] B. The production process includes the following steps:

[0044] S1. Raw material pretreatment: High alumina aggregate, corundum fine powder, silicon micro powder and silicon carbide are screened and impurities are removed using a vibrating screen (40 mesh) and magnetic separation equipment; calcium aluminate cement, sodium hexametaphosphate, calcium lignosulfonate, nano titanium dioxide and yttrium oxide are ground separately to ensure that their particle size is ≤0.044mm.

[0045] S2. Ingredient mixing: Add the pretreated high-alumina aggregate, corundum fine powder, silicon micro powder, and silicon carbide to a forced mixer and mix at 80 r / min for 3 minutes; then add calcium aluminate cement, sodium hexametaphosphate, calcium lignosulfonate, nano titanium dioxide, and yttrium oxide, and continue mixing for 5 minutes to obtain dry mix.

[0046] S3. Add water and stir: Add water equal to 8% of the dry mixture mass to the dry mixture and stir for 3 minutes to make a wet mixture.

[0047] S4. Aging treatment: Place the wet material in a sealed container at 20℃ and 60% relative humidity, turn it over every hour, and age for 2 hours.

[0048] S5. Molding: Pour the aged wet material into the mold and use vibration molding with a vibration frequency of 30Hz and a vibration time of 3 minutes.

[0049] S6. Curing: After molding, the castable is cured for 24 hours at a temperature of 20℃ and a relative humidity of 90%, and then dried at 100℃ for 2 hours.

[0050] S7. Finished product: After passing quality inspection, the inorganic castable is packaged to obtain the finished product.

[0051] Example 2

[0052] The present invention proposes an inorganic castable and its production process, which is implemented by the following technical solution:

[0053] A. Raw material ratio of inorganic castable.

[0054] By weight, the composition includes 50 parts high-alumina aggregate (89% alumina content, 3mm particle size), 22 parts corundum fine powder (97% alumina content, 0.066mm particle size), 10 parts silica powder (94% silica content, 0.15μm average particle size), 8 parts calcium aluminate cement (73% alumina content), 5 parts silicon carbide (93% purity, 0.07mm particle size), 1.2 parts sodium hexametaphosphate (96% purity), 0.9 parts calcium lignosulfonate (87% purity), 3 parts nano titanium dioxide (35nm average particle size), and 0.6 parts additives (a mixture of yttrium oxide and zirconium oxide, 1:1 by weight).

[0055] B. The production process includes the following steps:

[0056] S1. Raw material pretreatment: High alumina aggregate and other raw materials are screened and impurities are removed using a vibrating screen (60 mesh) and magnetic separation equipment, and calcium aluminate cement and other raw materials are ground to a particle size ≤0.044mm.

[0057] S2. Ingredient mixing: In a forced mixer, first mix the high-alumina aggregate, corundum fine powder, silicon micro powder, and silicon carbide at 100 r / min for 4 minutes, then add the remaining raw materials and mix for 6 minutes to form a dry mixture.

[0058] S3. Add water and stir: Add water equal to 10% of the dry mixture mass to the dry mixture and stir for 4 minutes to obtain a wet mixture.

[0059] S4. Aging treatment: Place the wet material in a sealed container at 25℃ and 70% relative humidity, turn it over once every hour, and age for 3 hours.

[0060] S5. Molding: Pour the wet material into the mold and use vibration molding with a vibration frequency of 40Hz and a vibration time of 4 minutes.

[0061] S6. Curing: The castable after molding is cured in an environment of 25℃ and 92% relative humidity for 36 hours, and then dried at 125℃ for 3 hours.

[0062] S7. Finished product: After passing inspection, the finished product is packaged.

[0063] Example 3

[0064] The present invention proposes an inorganic castable and its production process, which is implemented by the following technical solution:

[0065] A. Raw material proportions of inorganic castables

[0066] By weight, the composition includes 60 parts high-alumina aggregate (90% alumina content, 4mm particle size), 30 parts corundum fine powder (97% alumina content, 0.088mm particle size), 15 parts silica powder (94% silica content, 0.18μm average particle size), 10 parts calcium aluminate cement (75% alumina content), 8 parts silicon carbide (95% purity, 0.1mm particle size), 2 parts sodium hexametaphosphate (97% purity), 1.5 parts calcium lignosulfonate (89% purity), 5 parts nano titanium dioxide (50nm average particle size), and 1 part additive (a mixture of yttrium oxide and zirconium oxide, mass ratio 2:1).

[0067] B. The production process includes the following steps:

[0068] S1. Raw material pretreatment: The raw materials are screened and impurities are removed by vibrating screen (80 mesh) and magnetic separation equipment, and the raw materials such as calcium aluminate cement are ground to meet the particle size standard.

[0069] S2. Ingredient mixing: In a forced mixer, first mix the high-alumina aggregate and other raw materials at 120 r / min for 5 minutes, then add the remaining raw materials and mix for 8 minutes to obtain a dry mixture.

[0070] S3. Add water and stir: Add water equal to 12% of the dry mixture mass to the dry mixture and stir for 5 minutes to obtain wet material.

[0071] S4. Aging treatment: Place the wet material in a sealed container at 30℃ and 80% relative humidity, turn it over once every hour, and age for 4 hours.

[0072] S5. Molding: Pour the wet material into the mold and use vibration molding with a vibration frequency of 50Hz and a vibration time of 5 minutes.

[0073] S6. Curing: After molding, the castable is cured at 30℃ and 95% relative humidity for 48 hours, and then dried at 150℃ for 4 hours.

[0074] Finished product: Packaged after passing quality inspection.

[0075] Experimental Section

[0076] 1. Experimental Materials

[0077] I. Experimental Group: Inorganic castables prepared in Examples 1, 2, and 3;

[0078] II. Control Group:

[0079] Comparison with Castable A: A common high-alumina castable from a certain brand widely used in the metallurgical industry;

[0080] Compare with Castable B: another brand of low-cement-binder castable used in building material kilns.

[0081] 2. Experimental equipment

[0082] High-temperature furnace, compressive strength tester, thermal shock test device, slag erosion test equipment, electronic balance, vibrating screen, microscope.

[0083] 3. Experimental Methods

[0084] I. High-Temperature Strength Test

[0085] Each castable was made into a sample with a size of 40mm×40mm×160mm. After being kept at 1400℃ for 3 hours in a high-temperature furnace, it was cooled to room temperature and its compressive strength was measured using a compressive strength tester. Each sample was tested 3 times and the average value was taken.

[0086] II. Thermal shock resistance test

[0087] Prepare specimens with dimensions of 50mm × 50mm × 50mm. First, heat the specimens to 1100℃ and hold them at that temperature for 30 minutes. Then, quickly immerse them in cold water to cool them. This constitutes one thermal shock cycle. Repeat this process and record the number of thermal shock cycles required for the specimens to develop obvious cracks or for their strength to drop below 50% of their initial strength. Simultaneously, determine the strength retention rate after 15 thermal shock cycles.

[0088] III. Corrosion Resistance Test

[0089] Each castable was made into a cylindrical sample with a diameter of 50 mm and a height of 30 mm. The sample was placed in a crucible containing simulated slag (the composition of which was set according to the target industry). The sample was kept at a high temperature of 1400℃ for 5 hours. After cooling, the erosion of the sample was observed. The thickness of the eroded layer was measured using a microscope. Three different locations were selected for measurement of each sample, and the average value was taken.

[0090] 4. Experimental Results

[0091]

[0092]

[0093] 5. Experimental Data Analysis

[0094] I. High-temperature strength: The compressive strength of the inorganic castables in Examples 1-3 at 1400℃ is significantly higher than that of the control castables A and B. This is due to the reasonable proportion of raw materials such as high-alumina aggregate and corundum fine powder, as well as the addition of additives such as nano titanium dioxide, which effectively improves the crystal structure stability and density of the material at high temperature.

[0095] II. Thermal Shock Resistance: The thermal shock cycle count and strength retention rate after 15 thermal shock cycles of Examples 1-3 are superior to those of control castables A and B. The high thermal conductivity and low coefficient of thermal expansion of silicon carbide, combined with the optimized microstructure, greatly alleviate thermal stress and reduce crack formation, resulting in outstanding thermal shock resistance of the castables in Examples 1-3.

[0096] III. Corrosion Resistance: The corrosion layer thickness of Examples 1-3 is significantly smaller than that of control castables A and B, indicating that they can better resist slag corrosion. The dense corrosion-resistant layer formed by high-purity alumina raw materials and silicon carbide effectively blocks the penetration and corrosion of slag, extending the service life of the castables.

[0097] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An inorganic castable, characterized in that, By weight, it includes: 40-60 parts high-alumina aggregate, 15-30 parts fine corundum powder, 5-15 parts silica powder, 5-10 parts calcium aluminate cement, 3-8 parts silicon carbide, 0.5-2 parts sodium hexametaphosphate, 0.3-1.5 parts calcium lignosulfonate, 1-5 parts nano titanium dioxide, and 0.2-1 parts additives.

2. The inorganic castable according to claim 1, characterized in that, The alumina content of the high-alumina aggregate is ≥85%, and the particle size is 1-5mm; The alumina content of the corundum fine powder is ≥95%, and the particle size is ≤0.088mm; The silica content of the silica powder is ≥92%, and the average particle size is 0.1-0.2μm. Calcium aluminate cement is pure calcium aluminate cement with an alumina content of ≥70%; Silicon carbide purity ≥90%, particle size ≤0.1mm; Sodium hexametaphosphate is industrial grade with a purity of ≥95%. Calcium lignosulfonate is of industrial grade with a purity ≥85%. The average particle size of nano-titanium dioxide is 20-50 nm.

3. The inorganic castable according to claim 2, characterized in that, The high-alumina aggregate has an alumina content of 88-90% and a particle size of 2-4 mm; The alumina content of the fine corundum powder is 96-97%, and the particle size is 0.044-0.088 mm. The silica content of the silica powder is 93-94%, and the average particle size is 0.12-0.18 μm; The alumina content of calcium aluminate cement is 72-75%; The purity of silicon carbide is 92-95%, and the particle size is 0.05-0.1 mm.

4. The inorganic castable according to claim 1, characterized in that, The additives are one or more of yttrium oxide and zirconium oxide, or a mixture thereof.

5. The inorganic castable according to claim 4, characterized in that, The additive is a mixture of yttrium oxide and zirconium oxide, with a mass ratio of yttrium oxide to zirconium oxide of 1:1 to 2:

1.

6. A production process for inorganic castables as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. High-alumina aggregate, corundum fine powder, silica powder, and silicon carbide are screened and impurity removed respectively. Calcium aluminate cement, sodium hexametaphosphate, calcium lignosulfonate, nano titanium dioxide, and additives are ground respectively. S2. Weigh each component raw material according to the mass fraction. First, add high alumina aggregate, corundum fine powder, silicon micro powder, and silicon carbide into a forced mixer and mix for 3-5 minutes. Then add calcium aluminate cement, sodium hexametaphosphate, calcium lignosulfonate, nano titanium dioxide, and additives and continue mixing for 5-8 minutes to obtain dry mix. S3. Add 8-12% water by weight of the dry mixture to the dry mixture and stir for 3-5 minutes to obtain a wet mixture. S4. Aging the wet material for 2-4 hours at a temperature of 20-30℃ and a relative humidity of 60-80%; S5. Pour the aged wet material into the mold and use vibration molding or tamping molding. The vibration frequency is 30-50Hz and the vibration time is 3-5 minutes, or the tamping force is uniform and moderate. S6. Curing the molded casting material at a temperature of 20-30℃ and a relative humidity of ≥90% for 24-48 hours, and then drying it at a temperature of 100-150℃ for 2-4 hours. S7. After drying, the castable material undergoes quality inspection and is packaged after passing the inspection.

7. The production process of the inorganic castable according to claim 6, characterized in that, Raw material screening and impurity removal are carried out using a combination of vibrating screens and magnetic separators, with the vibrating screen having a mesh size of 40-80 mesh.

8. The production process of the inorganic castable according to claim 6, characterized in that, After grinding, the particle size of calcium aluminate cement, sodium hexametaphosphate, calcium lignosulfonate, 8-nanometer titanium dioxide, and additives is ≤0.044mm.

9. The production process of the inorganic castable according to claim 6, characterized in that, The mixing speed of a forced mixer is 80-120 r / min.

10. The production process of the inorganic castable according to claim 6, characterized in that, During the aging process, the wet material is turned over every hour.

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