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

Abstract

The invention discloses an iron runner castable with aluminum-rich natural minerals as main materials, and belongs to the field of unshaped refractory materials. The iron runner castable comprises the following components in percentage by mass: 66-70% of aluminum-rich natural mineral aggregate; 2-8% of 0-1mm silicon carbide; 1-2% of ball pitch; 6-8% of alumina micro powder; 1.5 to 2.5 percent of silicon dioxide micro powder; 1.5-2% of pure calcium aluminate cement; 0.8%-1.2% of special carbon black; 9-11% of silicon carbide powder; 2-3% of microcrystalline silicon nitride multiphase micro powder; 0.2 to 0.4 percent of boron carbide powder; 0.1%-0.16% of metal aluminum powder; 0.8 to 1.6 percent of metal silicon powder; 0.1 to 0.14 percent of boron oxide powder; 0.08 to 0.12 percent of explosion-proof fiber; and 0.1-0.2% of a dispersing agent. The obtained iron runner castable has the advantages of zero energy consumption of the main material, reduced cost, high strength, high volume density, good high-temperature performance and oxidation resistance, and important application prospects.

Description

Technical Field

[0001] The invention belongs to the field of amorphous refractory materials, and in particular relates to an iron trough castable with aluminum-rich natural minerals as main materials. Background Art

[0002] The iron trough is an important channel for high-temperature molten iron to flow from the blast furnace to the ladle. It is subjected to the violent erosion of 1500℃ high-temperature molten iron and slag for a long time. At present, corundum, silicon carbide and carbon iron trough castables are mainly used. However, the smelting process of electric fused corundum is a high-energy and high-pollution process, which causes great resource consumption. It is necessary to reduce the consumption of high-energy refractory raw materials.

[0003] ZL202110064608.0 discloses "an iron ditch castable and its preparation method", which uses 33-36% homogenized alumina to replace brown corundum. This solves the technical problem of the high price of iron ditch castables with brown corundum as aggregate. However, high-alumina alumina needs to be fired in a high-temperature kiln, which also consumes energy and pollutes the environment.

[0004] ZL201811417432.7 discloses a "long-life hot repair iron ditch castable", which uses calcium heptaaluminate to solve the problem of early reaction of metal aluminum powder before cement solidification, so that the metal aluminum powder in the iron ditch castable generates hydrogen in advance, and the gas is released to open the exhaust hole before the castable generates solidification strength, thereby increasing the stability of the anti-explosion performance of the castable. However, the use of brown corundum as the main material is costly and consumes a lot of energy.

[0005] ZL201610374825.9 discloses a "iron ditch castable containing more than 80% waste refractory materials", which uses waste refractory materials such as waste iron ditch castables to increase the proportion of waste refractory materials added to the castable. However, there are problems such as large fluctuations in the quality of waste refractory materials and limited resources. Summary of the invention

[0006] The purpose of the present invention is to provide an iron ditch castable with aluminum-rich natural mineral as the main material in view of the deficiencies in the prior art. The obtained iron ditch castable has zero energy consumption as the main material, reduces the cost, has high strength, high bulk density, good high temperature performance and antioxidant performance, and excellent comprehensive performance.

[0007] In order to solve the above problems, the present invention adopts the following technical solutions:

[0008] Provided is an iron trough castable with aluminum-rich natural mineral as the main material, wherein the raw material components are as follows by mass percentage:

[0009]

[0010]

[0011] in:

[0012] In the aluminum-rich natural mineral aggregate, Al2O3≥94wt%, SiO2≤3.5wt%, H2O≤1wt%, and water absorption rate≤1.6%;

[0013] In the microcrystalline silicon nitride composite powder, the main crystal phase is silicon nitride and silicon oxynitride. 90 ≤5μm.

[0014] Aluminum-rich natural minerals are natural minerals with extremely high aluminum oxide content and extremely low crystal water content. Due to the extremely low crystal water content, it can be used directly as aggregate without calcination or electric melting process. Its core indicators such as water absorption rate and aluminum content have reached the level of electric fused corundum.

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

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

[0017] According to the above scheme, the alumina powder has Al2O3≥99.5wt%, Na2O≤0.1wt%, and a fineness of D 50 ≤1.2 microns, the crystal diameter of the original crystal is controlled at 0.45-0.55um, the activity is very stable, the α phase conversion rate reaches more than 95%, it has better water reduction performance, good fluidity and good strength development.

[0018] According to the above scheme, the silica powder includes 98wt%≥SiO2≥94wt% of common silica powder with relatively high purity; preferably D 90 ≥5 microns. High-purity or submicron silicon dioxide powder is not suitable for the present invention, and its typical characteristics are: SiO2 ≥99wt%, pH value less than 4, and volume average particle size less than 0.3 microns.

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

[0020] According to the above scheme, the special carbon black is N990R ​​type produced in Germany.

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

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

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

[0024] According to the above scheme, the metal 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 metal silicon powder is ≤45 μm, and the Si content is ≥98.5%.

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

[0027] According to the above scheme, the dispersant is a mixture of polyacrylic acid liquid and alumina powder by spraying at a mass ratio of 1:3-1:4; wherein the molecular weight of polyacrylic acid is 5000-12000, and it is a highly efficient composite water reducing agent with excellent water reducing performance, and is not prone to water seepage, has good stability, and avoids swelling and cracking of iron ditch castables.

[0028] According to the above scheme, the boron oxide powder B2O3≥99.5% and the fineness is ≤44um.

[0029] The present invention provides an iron ditch castable with aluminum-rich natural mineral as the main material, wherein:

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

[0031] The present invention adopts microcrystalline silicon nitride composite powder, in which the main crystal phases are silicon nitride and silicon oxynitride. On the one hand, the silicon oxynitride in the composite powder has better chemical activity than silicon nitride, is more easily converted into SiAlON to form a Sialon binding phase, has better bonding with silicon carbide, and can produce higher bonding strength at high temperature than silicon nitride alone, significantly improves the hot strength, slag resistance and corrosion resistance of the castable, and can effectively improve the high-temperature oxidation resistance of the castable, making up for the decrease in oxidation resistance caused by the loss of crystal water of natural aggregate in the range of 500-600°C. On the other hand, the present invention selects finer microcrystalline silicon nitride composite powder, whose fineness is close to the original crystal size, avoids grain gaps, has better filling performance and surface activity, and does not increase the amount of water added to the castable.

[0032] At the same time, the present invention also uses boron oxide and boron carbide to cooperate with each other, wherein boron carbide can effectively compensate for the decrease in oxidation resistance caused by the loss of crystal water, but it will also cause a decrease in the hot strength of the iron ditch castable; and the present invention finds that a trace amount of boron oxide powder can improve the hot strength of the iron ditch castable, which not only effectively compensates for the decrease in hot strength caused by the addition of boron carbide, but also further improves the hot strength and assists boron carbide in improving oxidation resistance. Through the synergistic effect of boron oxide and boron carbide, while improving the medium and low temperature oxidation resistance of the castable, the hot strength of the iron ditch castable is also improved.

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

[0034] The present invention provides an iron ditch castable with aluminum-rich natural mineral as the main material. The newly discovered aluminum-rich natural mineral can be used as the aggregate of the iron ditch castable to directly replace the high-energy-consuming brown corundum without sintering and electric melting. The iron ditch castable is made of microcrystalline silicon nitride composite powder, boron oxide and boron carbide, and other components. The main material of the obtained iron ditch castable has zero energy consumption, reduced cost, high strength, high bulk density, good high-temperature performance and oxidation resistance, and excellent comprehensive performance. The bulk density of the iron ditch castable reaches 3g / cm 3 The above are reaching or even exceeding the conventional corundum iron ditch castables; the compressive strength after firing at 1450℃ generally exceeds 100MPa, and the hot flexural strength at 1400℃×1h exceeds 5MPa, which exceeds the conventional corundum iron ditch castables and has important application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0036] Figure 2 It is the XRD of natural mineral in the example.

[0037] Figure 3 TG-DSC of natural minerals in the examples. DETAILED DESCRIPTION

[0038] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0039] In the following examples, the specific indicators of the raw materials used are:

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

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

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

[0043] The silicon dioxide powder is 98wt%≥SiO2≥94wt%, ordinary silicon dioxide powder with higher purity, D 90 ≥5 microns.

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

[0045] The special carbon black is N990R ​​type produced in Germany.

[0046] The SiC content in the silicon carbide powder is ≥98% and the fineness is ≤74um.

[0047] In the microcrystalline silicon nitride composite powder, the main crystal phase is silicon nitride and silicon oxynitride. 90 ≤5μm, Si≥45%, 13%≤N≤16%.

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

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

[0050] The particle size of the metal silicon powder is ≤45 μm, and the Si content is ≥98.5%.

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

[0052] The dispersant is a mixture of polyacrylic acid liquid and alumina powder by spraying in a mass ratio of 1:3, wherein the molecular weight of polyacrylic acid is 5000-12000, and it is a highly efficient composite water reducing agent with excellent water reducing performance, and is not prone to water seepage, has good stability, and avoids swelling and cracking of iron ditch castables.

[0053] The boron oxide powder B2O3≥99.5% and the fineness is ≤44um.

[0054] The particle size of the natural mineral aggregate is 0.1-8mm; the natural mineral is a newly discovered mineral, which is a natural mineral with extremely high aluminum oxide content and extremely low crystal water. Conventional chemical analysis of refractory raw materials found that the contained Al2O3≥94wt%, SiO2≤3.5wt%, H2O≤1wt%, and water absorption rate≤1.6%; due to the extremely low crystal water content, it can be used directly as an aggregate without calcination or electric melting process, and its core indicators such as water absorption rate and aluminum content have reached the level of electric fused corundum.

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

[0056] Figure 1 This is the macroscopic morphology of natural mineral particles. It can be seen that the surface of natural mineral particles has a smooth and flat surface and obvious cleavage.

[0057] Figure 2 The XRD results of natural minerals show that the main crystal phase is Al2O3, in which there are small amounts of SiO2 and Al4O8H2. Al4O8H2 should be diaspore with -OH. The semi-quantitative results of the three are 92%, 3% and 5%.

[0058] Figure 3 This is the TG-DSC experimental result of natural minerals. It can be seen from the figure that there is obvious endothermic phenomenon and weight loss at 500-600℃. Combined with the XRD results, it can be known that it is caused by the thermal precipitation of -OH in diaspore Al4O8H2, and the maximum weight loss ratio is 0.71%.

[0059] Example 1

[0060] The iron trough castable is mainly made of natural minerals, and the components and their mass percentages are as follows:

[0061]

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

[0063] The iron ditch castable sample with natural mineral as the main material prepared in this embodiment was subjected to performance testing, and the results are shown in Table 1. The performance testing method adopted is carried out in accordance with the current national standard or industry standard, and the test results obtained are the average test results of 3 times (the same below).

[0064] Table 1. Performance test results of iron ditch castable samples made of natural minerals as the main material prepared in Example 1

[0065]

[0066] Example 2

[0067] The iron trough castable is mainly made of natural minerals, and the components and their mass percentages are as follows:

[0068]

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

[0070] The iron ditch castable sample with natural mineral as the main material prepared in this embodiment was subjected to performance testing, and the results are shown in Table 2. The performance testing method adopted is carried out in accordance with the current national standard or industry standard, and the test results obtained are the average test results of 3 times (the same below).

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

[0072]

[0073] Example 3

[0074] The iron trough castable is mainly made of natural minerals, and the components and their mass percentages are as follows:

[0075]

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

[0077] The iron ditch castable sample with natural mineral as the main material prepared in this embodiment was subjected to performance testing, and the results are shown in Table 3. The performance testing method adopted is carried out in accordance with the current national standard or industry standard, and the test results obtained are the average test results of 3 times (the same below).

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

[0079]

[0080] Example 4

[0081] The iron trough castable is mainly made of natural minerals, and the components and their mass percentages are as follows:

[0082]

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

[0084] The iron ditch castable sample with natural mineral as the main material prepared in this embodiment was subjected to performance testing, and the results are shown in Table 4. The performance testing method adopted is carried out in accordance with the current national standard or industry standard, and the test results obtained are the average test results of 3 times (the same below).

[0085] Table 4 Performance test results of iron ditch castable samples with natural minerals as the main material prepared in Example 4

[0086]

[0087] The above results show that the iron ditch castable with natural mineral as the main material of the present invention has the characteristics of high strength, high bulk density, good high temperature performance, and zero energy consumption of the main material.

[0088] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the invention.

Claims

1. An iron ditch castable with aluminum-rich natural mineral as the main material, characterized in that: In terms of mass percentage, the raw material components are: in: The aluminum-rich natural mineral aggregate contains Al2O3≥94wt%, SiO2≤3.5wt%, H2O≤1wt%, and water absorption rate≤1.6%; In the microcrystalline silicon nitride composite powder, the main crystal phase is silicon nitride and silicon oxynitride. 90 ≤5μm.

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

3. The iron ditch castable according to claim 1, characterized in that: The alumina powder has Al2O3≥99.5wt%, Na2O≤0.1wt%, and a fineness of D 50 ≤1.2 microns, the crystal diameter of the original crystal is controlled at 0.45-0.55um, and the α phase conversion rate reaches more than 95%; in the silicon dioxide micropowder, 98wt%≥SiO2≥94wt%.

4. The iron ditch castable according to claim 1, characterized in that: 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 ball asphalt is ≤1mm.

5. The iron ditch castable according to claim 1, characterized in that: The special carbon black is N990R ​​type produced in Germany.

6. The iron ditch castable according to claim 1, characterized in that: In the microcrystalline silicon nitride multiphase powder, Si≥45%, and N≤13%≤16%.

7. The iron ditch castable according to claim 1, characterized in that: In the boron carbide powder, B4C≥94% and fineness is≤45um.

8. The iron ditch castable according to claim 1, characterized in that: The metal aluminum powder is produced by nitrogen atomization process, with Al≥999% and fineness≤74um; the particle size of the metal silicon powder is≤45μm and Si content≥98.5%.

9. The iron ditch castable according to claim 1, characterized in that: The explosion-proof fiber is a polypropylene explosion-proof fiber with a melting point of 160-180°C and a length of 5-7mm; the dispersant is a mixture of polyacrylic acid liquid and alumina powder sprayed in a mass ratio of 1:3-1:4; the molecular weight of the polyacrylic acid is 5000-12000.

10. The iron trough castable according to claim 1, characterized in that: The boron oxide powder B2O3≥99.5% and the fineness is ≤44um.

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