Iron channel castable with aluminum-rich natural mineral as main material

Abstract

The application discloses an iron runner castable taking an aluminum-rich natural mineral as a main material and belongs to the field of amorphous refractory materials. The components of the iron runner castable are as follows in percentage by mass: aluminum-rich natural mineral aggregate 66-70%; silicon carbide 0-1mm: 2-8%; ball pitch 1-2%; alumina micropowder 6-8%; silica micropowder 1.5-2.5%; pure calcium aluminate cement 1.5-2%; special carbon black 0.8-1.2%; silicon carbide powder 9-11%; microcrystalline silicon nitride complex micropowder 2-3%; boron carbide powder 0.2-0.4%; metal aluminum powder 0.1-0.16%; metal silicon powder 0.8-1.6%; boron oxide powder 0.1-0.14%; explosion-proof fiber 0.08-0.12%; dispersing agent 0.1-0.2%. The obtained iron runner castable has zero energy consumption for the main material, reduces the cost, has high strength, high bulk density, good high-temperature performance and good oxidation resistance, and has important application prospect.

Description

Technical Field

[0001] This invention belongs to the field of unshaped refractory materials, specifically relating to an iron trough castable with aluminum-rich natural minerals as the main material. Background Technology

[0002] The refractory trough is a crucial channel for molten iron to flow from the blast furnace to the ladle. It is subjected to intense scouring from molten iron at 1500℃ and slag over a long period. Currently, corundum-based silicon carbide carbon refractory castables are primarily used for this purpose. However, the smelting process of electrofused corundum is energy-intensive and highly polluting, resulting in significant resource consumption. Therefore, it is necessary to reduce the consumption of energy-intensive refractory materials.

[0003] ZL202110064608.0 discloses "An iron trough castable and its preparation method", which uses 33-36% homogenized bauxite to replace brown corundum. This solves the technical problem of the high price of iron trough castables using brown corundum as aggregate. However, high-alumina bauxite requires high-temperature furnace firing, which also consumes energy and pollutes the environment.

[0004] ZL201811417432.7 discloses a "long-life hot-repair iron trench castable," which uses dodecacalcium heptaaluminate to address the premature reaction of metallic aluminum powder before cement curing. This allows the metallic aluminum powder in the castable to generate hydrogen gas earlier, opening the vent holes before the castable develops curing strength, thus increasing the stability of the castable's anti-explosion performance. However, using brown fused alumina as the main material results in high cost and high energy consumption.

[0005] ZL201610374825.9 discloses "an iron trough castable containing more than 80% waste refractory materials", which increases the proportion of waste refractory materials in the castable by using waste iron trough castable materials. However, it has problems such as large fluctuations in the quality of waste refractory materials and limited resources. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing an iron trough castable with aluminum-rich natural minerals as the main material. The resulting iron trough castable has zero energy consumption, reduces costs, and exhibits high strength, high density, good high-temperature performance and oxidation resistance, resulting in excellent overall performance.

[0007] To solve the above problems, the present invention adopts the following technical solution:

[0008] A castable refractory for iron troughs, primarily composed of aluminum-rich natural minerals, is provided. The raw material composition, by mass percentage, is as follows:

[0009]

[0010]

[0011] in:

[0012] The aluminum-rich natural mineral aggregate contains Al2O3 ≥ 94wt%, SiO2 ≤ 3.5wt%, H2O ≤ 1wt%, and water absorption ≤ 1.6%.

[0013] In microcrystalline silicon nitride multiphase powder, the main crystalline phases are silicon nitride and silicon oxynitride, D 90 ≤5μm.

[0014] Aluminum-rich natural minerals are natural minerals with extremely high alumina content and extremely low water of crystallization. Due to their extremely low water of crystallization content, they can be used directly as aggregates without calcination or electrofusion processes. Their core indicators, such as water absorption rate and aluminum content, have reached the level of electrofused corundum.

[0015] According to the above scheme, the silicon carbide 0.1-1mm has the following composition: SiC ≥ 98.5wt% and Fe2O3 ≤ 0.3wt%.

[0016] According to the above scheme, the particle size of the spherical asphalt is ≤1mm.

[0017] According to the above scheme, the alumina micro powder has Al2O3 ≥ 99.5 wt% and Na2O ≤ 0.1 wt%, and its fineness is D. 50 With a crystal size of ≤1.2 micrometers and a primary crystal diameter controlled at 0.45-0.55 μm, it exhibits very stable activity, an α-phase conversion rate of over 95%, better water-reducing performance, good fluidity, and good strength development.

[0018] According to the above scheme, the silica micro powder contains ordinary silica micro powder with a high purity of 98wt% ≥ SiO2 ≥ 94wt%; preferably, D 90 ≥5 micrometers. High-purity or submicron-sized silica powder is not applicable to this invention. Its typical characteristics are: SiO2 ≥ 99 wt%, pH value < 4, and volume average particle size < 0.3 micrometers.

[0019] According to the above scheme, the main chemical components of the pure calcium aluminate cement are Al2O3 68.5-70.5wt% and CaO 28.5-30.5wt%, with almost no other impurities; this calcium aluminate cement can effectively improve the low-temperature, medium-temperature and high-temperature strength and thermomechanical properties of cement.

[0020] According to the above scheme, the special carbon black is German-made N990R ​​type.

[0021] According to the above scheme, the silicon carbide powder has a SiC content of ≥98% and a fineness of ≤74um.

[0022] According to the above scheme, in the microcrystalline silicon nitride multiphase powder, Si ≥ 45%, and N ≤ 13% ≤ 16%.

[0023] According to the above scheme, the boron carbide powder has a B4C content of ≥94% and a fineness of ≤45μm.

[0024] According to the above scheme, the aluminum powder is produced by nitrogen atomization process, with Al≥99% and fineness≤74um.

[0025] According to the above scheme, the particle size of the metallic silicon powder is ≤45μm and the Si content is ≥98.5%.

[0026] According to the above scheme, the explosion-proof fiber is polypropylene explosion-proof fiber, with a melting point of 160-180℃ and a length of 5-7mm.

[0027] According to the above scheme, the dispersant is a spray mixture of polyacrylic acid liquid and alumina powder at a mass ratio of 1:3-1:4; wherein the polyacrylic acid has a molecular weight of 5000-12000 and is a highly efficient composite water-reducing agent with excellent water-reducing performance. At the same time, it is not prone to bleeding and has good stability, thus avoiding the expansion and cracking of the iron trough castable.

[0028] According to the above scheme, the boron oxide powder has a B2O3 content of ≥99.5% and a fineness of ≤44μm.

[0029] This invention provides an iron trough castable mainly composed of aluminum-rich natural minerals, wherein:

[0030] This invention uses a newly discovered natural mineral with extremely high aluminum content, extremely low crystal water content, and extremely low water absorption rate as the main material. It can directly replace high-energy-consuming brown corundum as aggregate in iron trough castable without sintering and electrofusion, thereby reducing costs.

[0031] This invention utilizes microcrystalline silicon nitride composite powder, in which the main crystalline phases are silicon nitride and silicon oxynitride. On one hand, the silicon oxynitride in the composite powder exhibits superior chemical activity compared to silicon nitride, more readily transforming into SiAlON to form a silane-bound phase. This results in better bonding with silicon carbide and, compared to silicon nitride alone, higher bonding strength at high temperatures. This significantly improves the hot strength, slag resistance, and erosion resistance of the castable, and effectively enhances its high-temperature oxidation resistance, compensating for the decrease in oxidation resistance caused by the loss of crystal water in natural aggregates within the 500-600℃ range. On the other hand, this invention selects finer microcrystalline silicon nitride composite powder, with a fineness close to the original crystal size, avoiding grain gaps and possessing superior filling performance and surface activity without increasing the water content of the castable.

[0032] Simultaneously, this invention employs a synergistic combination of boron oxide and boron carbide. While boron carbide effectively compensates for the decrease in antioxidant properties caused by the loss of crystal water, it also leads to a decrease in the hot strength of the iron trough castable. This invention discovers that trace amounts of boron oxide powder can improve the hot strength of the iron trough castable, not only effectively compensating for the decrease in hot strength caused by the addition of boron carbide but also further enhancing the hot strength and assisting boron carbide in improving antioxidant properties. Through the synergistic effect of boron oxide and boron carbide, the hot strength of the iron trough castable is improved while simultaneously enhancing its antioxidant properties at medium and low temperatures.

[0033] The beneficial effects of this invention are as follows:

[0034] This invention provides an iron trough castable with a newly discovered aluminum-rich natural mineral as the main material. This mineral can directly replace energy-intensive brown corundum as aggregate in the iron trough castable without sintering or electrofusion. Combined with microcrystalline silicon nitride multiphase powder, boron oxide, and boron carbide, along with other components, the resulting iron trough castable has zero energy consumption, reducing costs. It exhibits high strength, high density, good high-temperature performance, and excellent oxidation resistance, demonstrating superior overall performance. The bulk density of the iron trough castable reaches 3 g / cm³. 3 The above results meet or even exceed those of conventional corundum iron trough castables; the compressive strength after firing at 1450℃ generally exceeds 100MPa, and the hot flexural strength at 1400℃×1h exceeds 5MPa, surpassing conventional corundum iron trough castables and showing significant application potential. Attached Figure Description

[0035] Figure 1 The macroscopic morphology of natural mineral particles is shown in the examples.

[0036] Figure 2 The XRD pattern of the natural minerals shown in the examples is shown.

[0037] Figure 3 The example shows the TG-DSC of natural minerals. Detailed Implementation

[0038] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0039] In the following examples, the specific specifications of the raw materials used are as follows:

[0040] The silicon carbide 0-1mm: SiC≥98.5wt%, Fe2O3≤0.3wt%.

[0041] The particle size of the spherical asphalt is ≤1mm.

[0042] The alumina micro powder has Al2O3 ≥ 99.5 wt% and Na2O ≤ 0.1 wt%, and its fineness is D. 50 The crystal size is ≤1.2 micrometers, the crystal diameter of the primary crystal is controlled at 0.45-0.55 μm, the activity is very stable, and the α phase conversion rate reaches more than 95%.

[0043] The silica micro powder is 98wt% ≥ SiO2 ≥ 94wt%, a high-purity ordinary silica micro powder, D 90 ≥5 micrometers.

[0044] The main chemical components of the pure calcium aluminate cement are Al2O3 68.5-70.5wt% and CaO 28.5-30.5wt%, with almost no other impurities.

[0045] The special carbon black is of the German-made N990R ​​type.

[0046] The silicon carbide powder contains ≥98% SiC and has a fineness of ≤74µm.

[0047] In microcrystalline silicon nitride multiphase powder, the main crystalline phases are silicon nitride and silicon oxynitride, D 90 ≤5μm, Si≥45%, 13%≤N≤16%.

[0048] The boron carbide powder has a B4C content of >94% and a fineness of ≤45μm.

[0049] The aluminum powder is produced by nitrogen atomization process, with Al≥99% and a fineness≤74um.

[0050] The silicon metal powder has a particle size ≤45μm and a Si content ≥98.5%.

[0051] The explosion-proof fiber is polypropylene explosion-proof fiber, with a melting point of 160-180℃ and a length of 5-7mm.

[0052] The dispersant is a spray mixture of liquid polyacrylic acid and alumina powder at a mass ratio of 1:3. The polyacrylic acid has a molecular weight of 5000-12000 and is a highly efficient composite water-reducing agent with excellent water-reducing performance. It is also not prone to bleeding and has good stability, thus preventing the iron trough castable from bulging and cracking.

[0053] The boron oxide powder has a B2O3 content of ≥99.5% and a fineness of ≤44 μm.

[0054] The natural mineral aggregate has a particle size of 0.1-8mm. This natural mineral is a newly discovered mineral with extremely high alumina content and extremely low water of crystallization. Conventional chemical analysis of refractory raw materials shows that it contains Al2O3 ≥ 94wt%, SiO2 ≤ 3.5wt%, H2O ≤ 1wt%, and water absorption ≤ 1.6%. Due to its extremely low water of crystallization content, it can be used directly as aggregate without calcination or electrofusion processes. Its core indicators such as water absorption and aluminum content have reached the level of electrofused corundum.

[0055] The relevant physicochemical properties of natural minerals were tested, and the results are as follows: Figure 1-3 As shown, where:

[0056] Figure 1 The image shows the macroscopic morphology of natural mineral particles. It can be seen that the surface of natural mineral particles is smooth and flat, and they exhibit obvious cleavage.

[0057] Figure 2 The XRD results of the natural mineral show that its main crystalline phase is Al2O3, with small amounts of SiO2 and Al4O8H2 present. Al4O8H2 should be diaspore with -OH. The semi-quantitative results of the three are 92%, 3% and 5%, respectively.

[0058] Figure 3 The results of the TG-DSC experiment on the natural mineral show that there is obvious endothermic phenomenon and weight loss at 500-600℃. Combined with the XRD results, it can be seen that this is caused by the precipitation of -OH in diaspore Al4O8H2 upon heating, with the maximum weight loss ratio being 0.71%.

[0059] Example 1

[0060] The iron trough castable with natural minerals as the main material has the following components and their mass percentages:

[0061]

[0062] Weigh and mix all raw materials according to the above proportions; then add water (the mass of water is 4.0% of the total mass of all raw materials), stir evenly, and then vibrate to form the sample; after forming, the sample is naturally dried for 24 hours and then heat-treated at 110℃ for 24 hours to obtain an iron trough castable sample with natural minerals as the main material.

[0063] The performance of the iron trough castable samples prepared in this embodiment, mainly composed of natural minerals, was tested, and the results are shown in Table 1. The performance testing methods used were in accordance with current national or industry standards, and the test results are the average of three test results (hereinafter the same).

[0064] Table 1. Performance test results of the iron trough castable samples prepared in Example 1, which are mainly composed of natural minerals.

[0065]

[0066] Example 2

[0067] The iron trough castable with natural minerals as the main material has the following components and their mass percentages:

[0068]

[0069] Weigh and mix all raw materials according to the above proportions; then add water (the mass of water is 3.9% of the total mass of all raw materials), stir evenly, and then vibrate to form the sample; after forming, the sample is naturally dried for 24 hours and then heat-treated at 110℃ for 24 hours to obtain an iron trough castable sample with natural minerals as the main material.

[0070] The performance of the iron trough castable samples prepared in this embodiment, mainly composed of natural minerals, was tested, and the results are shown in Table 2. The performance testing methods used were in accordance with current national or industry standards, and the test results are the average of three test results (hereinafter the same).

[0071] Table 2. Performance test results of the iron trough castable samples prepared in Example 2 with natural minerals as the main material.

[0072]

[0073] Example 3

[0074] The iron trough castable with natural minerals as the main material has the following components and their mass percentages:

[0075]

[0076] Weigh and mix all raw materials according to the above proportions; then add water (the mass of water is 4.0% of the total mass of all raw materials), stir evenly, and then vibrate to form the sample; after forming, the sample is naturally dried for 24 hours and then heat-treated at 110℃ for 24 hours to obtain an iron trough castable sample with natural minerals as the main material.

[0077] The performance of the iron trough castable samples prepared in this embodiment, mainly composed of natural minerals, was tested, and the results are shown in Table 3. The performance testing methods used were in accordance with current national or industry standards, and the test results are the average of three test results (the same applies below).

[0078] Table 3. Performance test results of the iron trough castable samples prepared in Example 3 with natural minerals as the main material.

[0079]

[0080] Example 4

[0081] The iron trough castable with natural minerals as the main material has the following components and their mass percentages:

[0082]

[0083] Weigh and mix all raw materials according to the above proportions; then add water (the mass of water is 4.0% of the total mass of all raw materials), stir evenly, and then vibrate to form the sample; after forming, the sample is naturally dried for 24 hours and then heat-treated at 110℃ for 24 hours to obtain an iron trough castable sample with natural minerals as the main material.

[0084] The performance of the iron trough castable samples prepared in this embodiment, mainly composed of natural minerals, was tested, and the results are shown in Table 4. The performance testing methods used were in accordance with current national or industry standards, and the test results are the average of three test results (the same applies below).

[0085] Table 4. Performance test results of the iron trough castable samples prepared in Example 4, which are mainly composed of natural minerals.

[0086]

[0087] The above results indicate that the natural mineral-based iron trough castable of the present invention has the characteristics of high strength, high density, good high temperature performance, and zero energy consumption of the main material.

[0088] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A castable for iron runner using an aluminum-rich natural mineral as a main material, characterized by, The raw material components are, by mass percentage: Al-rich natural mineral aggregate 0.1-8 mm 66~70%; Silicon carbide 0.1-1 mm 2-8%; Spherical pitch 1-2%; Alumina powder 6~8%; Silica powder 1.5~2.5%; Pure calcium aluminate cement 1.5-2%; Special carbon black 0.8-1.2%; Silicon carbide powder 9-11%; Microcrystalline silicon nitride complex powder 2-3%; Boron carbide powder 0.2~0.4%; Metallic aluminum powder 0.1-0.16%; Metallic silicon powder 0.8~1.6%; Explosion-proof fiber 0.08~0.12%; Dispersant 0.1-0.2%; Boron oxide powder 0.1-0.14%; wherein: The Al2O3 content of the rich-aluminum natural mineral aggregate is ≥94wt%, the SiO2 content is ≤3.5wt%, the H2O content is ≤1wt%, and the water absorption is ≤1.6%; In the microcrystalline silicon nitride complex phase micro powder, the main crystal phase is silicon nitride and silicon oxynitride, D 90 ≤ 5 μm; The fineness of the alumina micropowder is D 50 ≤1.2 microns, and the α-phase conversion rate is 95% or more.

2. The iron run channel castable according to claim 1, characterized in that, The SiC content of the silicon carbide 0.1-1mm is ≥98.5wt%, and the Fe2O3 content is ≤0.3wt%; the SiC content of the silicon carbide powder is ≥98%, and the fineness is ≤74um.

3. The iron runner castable of claim 1, wherein The Al2O3 content of the alumina powder is ≥99.5wt%, and the Na2O content is ≤0.1wt%; the crystal diameter of the primary crystal is controlled to be 0.45-0.55um; the SiO2 content of the silica powder is 98wt%≥SiO2≥94wt%.

4. The iron runner castable of claim 1, wherein The main chemical components of the pure calcium aluminate cement are Al2O3 68.5-70.5wt% and CaO 28.5-30.5wt%; the particle size of the spherical pitch is ≤1mm.

5. The iron runner castable of claim 1, wherein The special carbon black is N990R type produced in Germany.

6. The iron runner castable of claim 1, wherein The Si content of the microcrystalline silicon nitride complex powder is ≥45%, and the N content is 13%≤N≤16%.

7. The iron runner castable of claim 1, wherein The B4C content of the boron carbide powder is ≥94%, and the fineness is ≤45um.

8. The iron runner castable of claim 1, wherein, The metallic aluminum powder is produced by nitrogen gas atomization process, with Al≥99% and fineness ≤74um; the particle size of the metallic silicon powder is ≤45um, and the Si content is ≥98.5%.

9. The iron runner castable of claim 1, wherein, The explosion-proof fiber is polypropylene explosion-proof fiber, with a melting point of 160-180 ℃ and a length of 5~7mm; the dispersant is a spray mixture of polyacrylic acid liquid and alumina powder in a mass ratio of 1:3-1:4; the molecular weight of the polyacrylic acid is 5000-12000.

10. The iron runner castable of claim 1, wherein, The B2O3 content of the boron oxide powder is ≥99.5%, and the fineness is ≤44um. ​

Images