Preparation of Al from waste Mg-C materials 2 O 3 -SiC-MgAl 2 O 4 -C castable and its preparation method

Abstract

The present invention discloses a method for preparing an Al 2 O 3 -SiC-MgAl 2 O 4 -C castable and its preparation method, belonging to the technical field of unshaped refractory materials. The raw materials include white fused alumina aggregate, silicon carbide, waste magnesia-carbon brick, spherical asphalt, α-Al 2 O 3 fine powder, silica fine powder, elemental silicon powder, calcium aluminate cement, and an additional water reducer and water are added. After mixing and kneading the above materials in a mixer, they are stirred and cast into shape, demolded after room temperature curing, and heat-treated in a carbon-buried atmosphere after drying for 36 hours to 50 hours. The heat treatment temperature is 1550°C to 1650°C, and after holding for 3 hours to 5 hours, a refractory castable for the tapping spout prepared from waste magnesia-carbon bricks is obtained. The refractory castable prepared by the present invention has excellent high-temperature performance and strong oxidation resistance, significantly improves the service life, and at the same time enhances the recycling of resources.

Description

Technical Field

[0001] The present invention belongs to the technical field of unshaped refractory materials, and particularly relates to an Al 2 O 3 -SiC-MgAl 2 O 4 -C castable and a preparation method thereof. Background Art

[0002] Chinese Patent Application No.: 202010227598.3, Invention Title: An Al 2 O 3 -SiC-C brick and a preparation method thereof. This application prepared an Al 2 O 3 -SiC-C brick with good slag erosion resistance and hot metal scouring resistance, high high-temperature flexural strength, excellent thermal shock stability, and stable high-temperature thermal expansion rate and residual expansion rate by using 20-30 parts of recycled material particles, 30-40 parts of bauxite particles, 10-20 parts of corundum particles, 10-20 parts of corundum fine powder, 5-15 parts of silicon carbide fine powder, 5-15 parts of flake graphite, 0-5 parts of additives, and 2-6 parts of binder.

[0003] Chinese Patent Application No.: 202210319678.0, Invention Title: A composite lining brick for torpedo ladle produced by recycling various waste refractories. This application consists of super-grade bauxite clinker, recycled waste silicon carbide, white corundum, waste slide plate, expansive agent, recycled graphite, alumina micro-powder, high-temperature pitch powder, antioxidant, complex magnesium-aluminum binder, and phenolic resin. The raw materials of the protective layer lining brick are composed of recycled waste torpedo ladle particles, waste slide plate, recycled waste silicon carbide, recycled waste iron runner material, recycled waste corundum fine powder, expansive agent, recycled graphite, complex magnesium-aluminum binder, and phenolic resin to prepare a composite lining brick for torpedo ladle. The composite lining brick for torpedo ladle has the same performance indexes as the existing torpedo ladle bricks and better use effects while significantly reducing production costs. The comprehensive cost is greatly reduced, and the refractory consumption per unit is greatly reduced, having good social and economic benefits.

[0004] From the above research results, it can be seen that using waste refractories to prepare Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable helps to improve the service performance of Al 2 O 3 -SiC-C refractory castable, reduce production costs, protect the environment, and promote circular economy.

[0005] Therefore, it is urgent to explore a way to recycle waste refractory materials in the iron and steel industry. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing Al 2 O 3 -SiC-MgAl 2 O 4 -C castable and its preparation method to solve the above problems.

[0007] The present invention achieves the above purpose through the following technical solutions:

[0008] A method for preparing Al 2 O 3 -SiC-MgAl 2 O 4 -C castable, using white fused alumina aggregate at 50.0wt%-60.0wt%, silicon carbide at 5.0wt%-15.0wt%, waste magnesia-carbon brick at 10.0wt%-20.0wt%, spherical pitch at 1.0wt%-2.0wt%, α-Al 2 O 3 fine powder at 5.0wt%-10.0wt%, silica fine powder at 5.0wt%-10.0wt%, elemental silicon powder at 1.0wt%-3.0wt%, calcium aluminate cement at 1.0wt%-3.0wt% as raw materials, and adding 0.1wt%-0.4wt% of water reducing agent based on the above raw materials and 4.0wt%-8.0wt% of water based on the above raw materials.

[0009] Among them, the white fused alumina aggregate is composed of 10.0wt%-40.0wt% of 8mm-5mm white fused alumina aggregate, 20.0wt%-30.0wt% of 5mm-3mm white fused alumina aggregate, 20.0wt%-30.0wt% of 3mm-1mm white fused alumina aggregate, and 20.0wt%-50.0wt% of 1mm-0.088mm white fused alumina aggregate as raw materials.

[0010] Among them, the silicon carbide is composed of 10.0wt%-20.0wt% of 3mm-1mm silicon carbide, 10.0wt%-20.0wt% of 1mm-0.088mm silicon carbide, and 40.0wt%-70.0wt% of silicon carbide less than 0.088mm as raw materials.

[0011] Among them, the MgO content in the waste magnesia-carbon brick is ≥75.0%, the C content is ≥10.0%, and the bulk density is ≥2.9g / cm 3 .

[0012] Among them, the SiO 2 content in the silica fine powder is ≥97.0%.

[0013] Among them, the water reducing agent is sodium tripolyphosphate or sodium hexametaphosphate.

[0014] Among them, the Si content in the elemental silicon powder is ≥ 95.0%.

[0015] Among them, the alumina content in the calcium aluminate cement is ≥ 65.0%.

[0016] The present invention also provides a method for preparing Al 2 O 3 -SiC-MgAl 2 O 4 -C castable, using white corundum aggregate, silicon carbide, waste magnesia-carbon brick, spherical pitch, α-Al 2 O 3 fine powder, silica fine powder, elemental silicon powder, calcium aluminate cement as raw materials, adding water reducing agent and water externally; after mixing and kneading the above materials in a mixer, stirring and casting into shape, demolding after room temperature curing, drying for 36 hours - 50 hours and then performing heat treatment in a carbon-embedded atmosphere, the heat treatment temperature is 1550 °C - 1650 °C, and after holding for 3 hours - 5 hours, the tapping trough using waste magnesia-carbon brick to prepare Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable is obtained.

[0017] Among them, after heat treatment, the bulk density of the Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable is 2.8 g / cm 3 - 3.0 g / cm 3 , the flexural strength is 32 - 37 MPa, the flexural strength retention rate after 3 times of air-cooled thermal shock test is 73% - 82%, the oxidation index of the 1400 °C oxidation test is 5% - 10%, and the high-temperature flexural strength at 1400 °C is 9 MPa - 14 MPa.

[0018] The advantages of the present invention are as follows:

[0019] By introducing waste magnesia-carbon brick, replacing the carbon black in the original Al 2 O 3 -SiC-C refractory castable, so as to achieve the role of replacing the carbon source and reducing the consumption of carbon resources; the waste magnesia-carbon brick is introduced into the refractory castable in the form of aggregate, and carbon is stored in the particles, which can significantly reduce the contact area between carbon and air during service, thereby reducing the oxidation rate and improving Al 2 O 3 -SiC-MgAl2 O 4 -C refractory castable antioxidant capacity; waste magnesia-carbon bricks are introduced in the form of aggregates and can react with α-Al in the matrix 2 O 3 to form a spinel phase. On the one hand, the formation of spinel can strengthen the interface between the aggregate and the matrix, fill part of the gaps between the aggregate and the matrix, and improve the high-temperature performance. On the other hand, the formation of spinel can improve the Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable internal phase composition, improve thermal shock resistance and high-temperature strength. The in-situ reaction of spinel will cause volume expansion, but Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable added silica fume and elemental silicon powder will react with other phases at high temperature to form a low-melting phase. On the one hand, it can improve the Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable sintering ability, relieve the expansion caused by the formation of spinel. Secondly, the generated liquid phase can fill the voids, reduce the porosity, and improve the high-temperature performance. Therefore, the Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable has excellent high-temperature performance, strong antioxidant performance, significantly improves the service life, and at the same time enhances the recycling of resources. Specific embodiments

[0020] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to these embodiments.

[0021] Example 1

[0022] The present invention relates to a method for preparing Al 2 O 3 -SiC-MgAl 2 O 4 -C castable from waste magnesia-carbon materials and its preparation method. The technical solution is as follows:

[0023] Using 50wt% white fused alumina aggregate, 10wt% silicon carbide, 20wt% waste magnesia-carbon bricks, 2.0wt% spherical pitch, 7wt% α-Al 2 O 3Using fine powder, 7 wt% silica fine powder, 1.0 wt% elemental silicon powder, and 3 wt% calcium aluminate cement as raw materials; adding 0.2 wt% water reducing agent based on the raw materials and 6.0 wt% water based on the raw materials. After kneading the above materials in a mixer for 7 minutes, stirring for 4 minutes, then casting and molding. After curing at room temperature for 40 hours, demolding, drying for 36 hours, and then performing heat treatment in a carbon-buried atmosphere. The heat treatment temperature is 1550 °C, and after holding for 3 hours, an Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable for the iron runner is prepared.

[0024] Among them, white fused alumina aggregates with a size of 8 mm - 5 mm account for 30 wt%, white fused alumina aggregates with a size of 5 mm - 3 mm account for 30.0 wt%, white fused alumina aggregates with a size of 3 mm - 1 mm account for 20.0 wt%, and white fused alumina aggregates with a size of 1 mm - 0.088 mm account for 20.0 wt%.

[0025] Among them, silicon carbide with a size of 3 mm - 1 mm accounts for 20.0 wt%, silicon carbide with a size of 1 mm - 0.088 mm accounts for 20.0 wt%, and silicon carbide with a size less than 0.088 mm accounts for 60.0 wt% of the silicon carbide.

[0026] Among them, the MgO content in the waste magnesia-carbon brick is 78.0%, the C content is 12.0%, and the bulk density is 2.97 g / cm 3 , waste magnesia-carbon bricks with a size of 1 mm - 3 mm account for 50.0%, and waste magnesia-carbon bricks with a size of 0 mm - 1 mm account for 50.0%.

[0027] Among them, the SiO 2 content in the silica fine powder is 97.0%.

[0028] Among them, the water reducing agent is sodium tripolyphosphate.

[0029] Among them, the Si content in the elemental silicon powder is 96.0%.

[0030] Among them, the alumina content in the calcium aluminate cement is 67.0%.

[0031] After testing, the bulk density of the Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable after heat treatment is 2.93 g / cm 3 , the flexural strength is 34 MPa, the flexural strength retention rate after 3 times of air-cooling thermal shock tests is 77%, the oxidation index in the 1400 °C oxidation test is 6%, and the high-temperature flexural strength at 1400 °C is 12 MPa.

[0032] Example 2

[0033] The present invention relates to a method for preparing Al 2 O 3 -SiC-MgAl 2 O 4 -C castable and its preparation method. The technical solution is as follows:

[0034] Using 55.0wt% white fused alumina aggregate, 15.0wt% silicon carbide, 10.0wt% waste magnesia-carbon brick, 2.0wt% spherical pitch, 7.0wt% α-Al 2 O 3 fine powder, 8.0wt% silica fine powder, 2.0wt% elemental silicon powder, and 1.0wt% calcium aluminate cement as raw materials; adding 0.3wt% water reducing agent based on the external raw materials and 5.0wt% water based on the raw materials. After mixing the above materials in a mixer for 8 minutes, stirring for 4 minutes, then casting and molding, demolding after curing at room temperature for 48 hours, drying for 36 hours, and then performing heat treatment in a carbon-embedded atmosphere. The heat treatment temperature is 1650°C, and after holding for 5 hours, an iron runner using waste magnesia-carbon brick to prepare Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable is obtained.

[0035] Among them, 8mm - 5mm white fused alumina aggregate accounts for 30.0wt%, 5mm - 3mm white fused alumina aggregate accounts for 20.0wt%, 3mm - 1mm white fused alumina aggregate accounts for 20.0wt%, and 1mm - 0.088mm white fused alumina aggregate accounts for 30.0wt%.

[0036] Among them, 3mm - 1mm silicon carbide accounts for 20.0wt%, 1mm - 0.088mm silicon carbide accounts for 10.0wt%, and silicon carbide less than 0.088mm accounts for 70.0wt%.

[0037] Among them, the MgO content in the waste magnesia-carbon brick is 85%, the C content is 10%, and the bulk density is 2.92g / cm 3 , 1mm - 3mm waste magnesia-carbon brick accounts for 60.0%, and 0mm - 1mm waste magnesia-carbon brick accounts for 40.0%.

[0038] Among them, the SiO 2 content in the silica fine powder is 98%.

[0039] Among them, the water reducing agent is sodium hexametaphosphate.

[0040] Among them, the Si content in the elemental silicon powder is 97.0%.

[0041] Among them, the alumina content in the calcium aluminate cement is 68.0%.

[0042] After detection, after heat treatment, Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable has a bulk density of 2.94 g / cm 3 , a flexural strength of 36 MPa, a flexural strength retention rate of 80% after 3 times of air-cooling thermal shock tests, an oxidation index of 7% in the oxidation test at 1400 °C, and a high-temperature flexural strength of 14 MPa at 1400 °C.

[0043] Example 3

[0044] The present invention relates to a method for preparing Al 2 O 3 -SiC-MgAl 2 O 4 -C castable and its preparation method. The technical solution is as follows:

[0045] Using 50.0 wt% of white fused alumina aggregate, 15.0 wt% of silicon carbide, 10.0 wt% of waste magnesia-carbon brick, 2.0 wt% of spherical pitch, 10.0 wt% of α-Al 2 O 3 fine powder, 10.0 wt% of silica fine powder, 2.0 wt% of elemental silicon powder, and 1.0 wt% of calcium aluminate cement as raw materials; adding 0.1 wt% of water reducing agent based on the raw materials and 8.0 wt% of water based on the raw materials. After mixing the above materials in a mixer for 6 minutes, stirring for 5 minutes and then casting and molding, demolding after curing at room temperature for 50 hours, drying for 50 hours and then performing heat treatment in a carbon-buried atmosphere. The heat treatment temperature is 1600 °C, and after holding for 4 hours, the tapping runner using waste magnesia-carbon brick to prepare Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable is obtained.

[0046] Among them, 8 mm - 5 mm white fused alumina aggregate accounts for 40.0 wt%, 5 mm - 3 mm white fused alumina aggregate accounts for 20.0 wt%, 3 mm - 1 mm white fused alumina aggregate accounts for 20.0 wt%, and 1 mm - 0.088 mm white fused alumina aggregate accounts for 20.0 wt%.

[0047] Among them, 3 mm - 1 mm silicon carbide accounts for 20.0 wt%, 1 mm - 0.088 mm silicon carbide accounts for 10.0 wt%, and less than 0.088 mm silicon carbide accounts for 70.0 wt%.

[0048] Among them, the MgO content in the waste magnesia-carbon brick is 76.0%, the C content is 13.0%, and the bulk density is 2.91 g / cm3 Among them, the waste magnesia-carbon bricks with a size of 1 mm - 3 mm account for 70.0% of the total waste magnesia-carbon bricks, and the waste magnesia-carbon bricks with a size of 0 mm - 1 mm account for 30.0% of the total waste magnesia-carbon bricks.

[0049] Among them, the SiO content in the silica fine powder is 2 97.0%.

[0050] Among them, the water reducing agent is sodium tripolyphosphate.

[0051] Among them, the Si content in the elemental silicon powder is 97.0%.

[0052] Among them, the alumina content in the calcium aluminate cement is 69.0%.

[0053] After testing, the bulk density of the Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable is 2.98 g / cm 3 , the flexural strength is 35 MPa, the flexural strength retention rate after 3 times of air-cooling thermal shock test is 81%, the oxidation index in the oxidation test at 1400 °C is 5%, and the high-temperature flexural strength at 1400 °C is 12 MPa.

[0054] Due to the adoption of the above technical solution, the present invention has the following positive effects compared with the prior art:

[0055] The present invention introduces waste magnesia-carbon bricks as a new carbon source into the Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable, which helps to generate the third phase, improve the microstructure interface and enhance the service performance, and also helps to reduce the consumption of carbon resources and is beneficial to environmental protection.

[0056] The Al 2 O 3 -SiC-MgAl 2 O 4 -C refractory castable prepared by the present invention has excellent high-temperature performance, strong oxidation resistance, and remarkable improvement effect on the service life.

[0057] The above embodiments only represent the implementation modes of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation of the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A method for preparing Al2O3-SiC-MgAl2O4-C castable from waste magnesium-carbon materials, characterized in that: 50.0wt%-60.0wt% of white corundum aggregate, 5.0wt%-15.0wt% of silicon carbide, 10.0wt%-20.0wt% of waste magnesia carbon bricks, 1.0wt%-2.0wt% of spherical asphalt, 5.0wt%-10.0wt% of α-Al2O3 fine powder, 5.0wt%-10.0wt% of silicon oxide fine powder, 1.0wt%-3.0wt% of elemental silicon powder, 1.0wt%-3.0wt% of calcium aluminate cement are used as raw materials, 0.1wt%-0.4wt% of water reducing agent of the raw materials and 4.0wt%-8.0wt% of water of the raw materials are added, and the waste magnesia carbon bricks are introduced into the refractory castable in the form of aggregate. The volume density of the Al2O3-SiC-MgAl2O4-C refractory castable after heat treatment is 2.8g / cm 3 -3.0g / cm 3 The flexural strength is 32-37MPa, the flexural strength retention rate after three wind-cooled thermal shock tests is 73%-82%, the oxidation index of the 1400℃ antioxidant test is 5%-10%, and the high-temperature flexural strength at 1400℃ is 9MPa-14MPa.

2. The Al2O3-SiC-MgAl2O4-C castable prepared from waste magnesium-carbon materials according to claim 1, characterized in that: The white corundum aggregate is made of 10.0wt%-40.0wt% of 8mm-5mm white corundum aggregate, 20.0wt%-30.0wt% of 5mm-3mm white corundum aggregate, 20.0wt%-30.0wt% of 3mm-1mm white corundum aggregate, and 20.0wt%-50.0wt% of 1mm-0.088mm white corundum aggregate.

3. The Al2O3-SiC-MgAl2O4-C castable prepared from waste magnesium-carbon materials according to claim 1, characterized in that: The silicon carbide is made of 10.0wt%-20.0wt% of 3mm-1mm silicon carbide, 10.0wt%-20.0wt% of 1mm-0.088mm silicon carbide, and 40.0wt%-70.0wt% of silicon carbide less than 0.088mm.

4. The Al2O3-SiC-MgAl2O4-C castable prepared from waste magnesium-carbon materials according to claim 1, characterized in that: The waste magnesia carbon bricks have a MgO content of ≥75.0%, a C content of ≥10.0%, and a bulk density of ≥2.9 g / cm 3 .

5. The Al2O3-SiC-MgAl2O4-C castable prepared from waste magnesium-carbon materials according to claim 1, characterized in that: The SiO2 content in the silicon oxide fine powder is ≥97.0%.

6. The Al2O3-SiC-MgAl2O4-C castable prepared from waste magnesium-carbon materials according to claim 1, characterized in that: The water reducing agent is sodium tripolyphosphate or sodium hexametaphosphate.

7. The Al2O3-SiC-MgAl2O4-C castable prepared from waste magnesium-carbon materials according to claim 1, characterized in that: The Si content in the elemental silicon powder is ≥95.0%.

8. The Al2O3-SiC-MgAl2O4-C castable prepared from waste magnesium-carbon materials according to claim 1, characterized in that: The alumina content in the calcium aluminate cement is ≥65.0%.

9. A method for preparing Al2O3-SiC-MgAl2O4-C castable from waste magnesium-carbon materials according to any one of claims 1-8, characterized in that: White corundum aggregate, silicon carbide, waste magnesia carbon bricks, spherical asphalt, α-Al2O3 fine powder, silicon oxide fine powder, elemental silicon powder, calcium aluminate cement are used as raw materials, and a water reducer and water are added; the above materials are mixed in a mixer, stirred and cast into shape, and demolded after room temperature curing. After drying for 36 to 50 hours, heat treatment is carried out in a carbon-buried atmosphere at a heat treatment temperature of 1550°C to 1650°C, and the heat treatment is kept for 3 to 5 hours to obtain Al2O3-SiC-MgAl2O4-C refractory castable for iron ditch using waste magnesia carbon bricks.