Asphalt coated aluminum powder iron runner castable

Abstract

The invention belongs to the technical field of refractory materials, and relates to preparation of a castable for an iron runner. The invention provides an iron runner castable method for coating aluminum powder with asphalt. The castable is composed of 55 to 62% of corundum with a particle size of 25 to 0.044 mm, 17 to 25% of silicon carbide with a particle size of 2.5 to 0.044 mm, 5 to 8% of alumina micro powder with a particle size of 5 to 0.5 [mu] m, 0.5 to 1% of silica micro powder with a particle size of less than 1 [mu] m, 1.0 to 1.5% of pure calcium aluminate cement with a particle size of less than 25 [mu] m, 0.2 to 0.5% of andalusite with a particle size of 1 to 0.12 mm, 5 to 8% of asphalt coated aluminum powder with a particle size of 1 to 0.2 mm, 0.5 to 1.5% of carbon black with a particle size of less than 1 [mu] m, 0.08 to 0.12% of organic fiber, and 0.1 to 0.2 The perfect combination of the spherical asphalt and the aluminum powder well solves the problems that the aluminum powder is unstable when meeting water at normal temperature and the porosity is increased due to the increase of the addition amount of the spherical asphalt, and the service life of the tapping main channel is greatly prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials, and mainly relates to an iron ditch castable of asphalt-coated aluminum powder. Background Art

[0002] The blast furnace iron ditch mainly uses Al2O3-SiC-C castable, which will be washed, eroded and penetrated by molten iron and iron slag during use; carbon has the characteristics of high refractoriness, large thermal conductivity, small thermal expansion coefficient, and not easily wetted by molten oxides such as slag. The addition of carbon-containing raw materials can improve the thermal shock resistance and slag resistance of Al2O3-SiC-C castable, but C is easily oxidized at high temperature, resulting in structural collapse and performance degradation of Al2O3-SiC-C castable.

[0003] How to reduce or even avoid the oxidation of C is the key to maintaining the excellent performance of Al2O3-SiC-C castables; the commonly used method is to add non-oxides such as silicon powder, aluminum powder, boron carbide as antioxidants to form a low-melting phase or a binding phase at high temperature to plug and close the pores; aluminum powder is an ideal antioxidant. It softens at medium temperature and fills the pores. At high temperatures, aluminum powder can form a binding phase with silicon, calcium, magnesium, carbon, etc. to enhance the strength of the material and greatly improve the high-temperature performance. However, when cast at room temperature, aluminum powder is easily hydrated, causing cracks in the castable, so the addition amount is generally controlled between 0.1 and 0.2%.

[0004] Asphalt is a high-quality carbon source with good hydrophilicity. Its main manifestation is that during the heating process of the material, it can penetrate into the pores very well, and volatilize at high temperature to condense in the pores and between particles in the form of gas, thus achieving uniform distribution of carbon in the entire castable. The carbon formed after carbonization of the asphalt has high reaction activity and is easier to react with silicon powder and aluminum powder in the castable to enhance the structure of the castable and improve the mechanical properties of the castable. In order to minimize the impact of asphalt on the amount of water added to the castable, spherical asphalt with a particle size of 0.2 to 1 mm is generally used. Due to the limitations of the manufacturing process, spherical asphalt has a hollow structure. After being added to the castable, it will cause a significant increase in the porosity of the material. The amount added is generally controlled between 2 and 3%.

[0005] Since spherical asphalt plays an irreplaceable role in Al2O3-SiC-C castables and aluminum powder has excellent antioxidant properties, it is crucial to increase the porosity of the castable while increasing the amount of asphalt added and taking into account its high-temperature antioxidant properties, in order to improve the slag resistance of the Al2O3-SiC-C castable and extend its service life. Summary of the invention

[0006] In order to minimize the effect of spherical asphalt on the porosity of Al2O3-SiC-C castable, while increasing the amount of aluminum powder added, improving the high temperature performance of the castable and increasing its iron throughput, the present invention proposes an iron ditch castable with asphalt-coated aluminum powder.

[0007] The present invention adopts the following technical solutions to achieve the above-mentioned purpose: An iron ditch castable with asphalt-coated aluminum powder, characterized in that the raw material composition, particle size and mass percentage of the iron ditch castable are as follows: Corundum 25-0.044mm 55~62%; Silicon carbide 2.5-0.044mm 17~25%; Alumina powder 5-0.5μm 5~8%; Silicon oxide powder <1μm 0.5~1%; Pure calcium aluminate cement <25μm 1.0~1.5% Andalusite 1-0.12mm 0.2~0.5%; Asphalt coated aluminum powder 1-0.2mm 5~8%; Carbon black <1μm 0.5~1.5%; Organic fiber 0.08-0.12%; Water reducing agent 0.1~0.2%; The asphalt-coated aluminum powder refers to liquid asphalt sprayed with compressed air containing aluminum powder ≤0.044 mm, naturally cooled in a cooling tower to form a semi-finished product, and then sieved to obtain solid spherical asphalt that meets the requirements.

[0008] Mix all the above raw materials evenly, package them, and send them to the iron ditch site for on-site pouring.

[0009] The present invention proposes an iron ditch castable of asphalt-coated aluminum powder, the room temperature softening point of the asphalt is above 110°C, and during the casting process, the contact between the aluminum powder coated with asphalt and water is basically isolated, which largely avoids the reaction of aluminum powder and water to generate Al(OH)3, and reduces the cracking problem of the material during room temperature curing and baking; due to the reduction of low-melting phases, the corrosion resistance and penetration resistance of the material are significantly improved at high temperatures, and at the same time, aluminum and carbon form aluminum carbide to enhance the strength of the material, and the material's anti-scouring ability is greatly enhanced; at medium temperature, the softening of aluminum powder can not only fill the pores, but also absorb the thermal stress of the material, so that the thermal shock resistance of the material is also improved. DETAILED DESCRIPTION

[0010] The specific technical scheme of the present invention is further described below in conjunction with the embodiments and with reference to the scheme of the normal iron-out main groove to form a comparative example. Example 1

[0011] An iron ditch castable of asphalt-coated aluminum powder, characterized in that the raw material composition, particle size and mass percentage of the material are as follows: Corundum 25-0.044mm 62%; Silicon carbide 2.5-0.044mm 19%; Alumina powder 5-0.5μm 7.8%; Silica powder <1μm 0.5%; Pure calcium aluminate cement<25μm 1.0% Andalusite 1-0.12mm 0.5%; Asphalt coated aluminum powder 1-0.2mm 8%; Carbon black<1μm 1.0%; Organic fiber 0.1%; Water reducing agent 0.1%; Example 2

[0012] An iron ditch castable of asphalt-coated aluminum powder, characterized in that the raw material composition, particle size and mass percentage of the material are as follows: Corundum 25-0.044mm 60.5%; Silicon carbide 2.5-0.044mm 25%; Alumina powder 5-0.5μm 5%; Silica powder <1μm 1%; Pure calcium aluminate cement<25μm 1.5% Andalusite 1-0.12mm 0.3%; Asphalt coated aluminum powder 1-0.2mm 5%; Carbon black <1μm 1.5%; Organic fiber 0.1%; Water reducing agent 0.1%; Comparative Example 1

[0013] The castable material for the normal main trough of iron tapping is characterized in that the raw material composition, particle size and mass percentage of the material are as follows: Corundum 25-0.044mm 62%; Silicon carbide 2.5-0.044mm 22%; Alumina powder 5-0.5μm 7%; Silica powder <1μm 1%; Pure calcium aluminate cement <25μm 1.5%; Andalusite 1-0.12mm 0.6%; Carbon source 1-0.044mm 2.6%; Elemental silicon 0.12-0.044mm 3%; Aluminum metal 0.088-0.044mm 0.08%; Organic fiber 0.1%; Water reducing agent 0.12%; Comparative Example 2

[0014] The castable material for the normal iron tapping main ditch is characterized in that the raw material composition, particle size and mass percentage of the material are as follows: Corundum 25-0.044mm 64%; Silicon carbide 2.5-0.044mm 17%; Alumina powder 5-0.5μm 8.5%; Silica powder <1μm 2.5%; Pure calcium aluminate cement <25μm 3%; Andalusite 1-0.12mm 1.4%; Carbon source 1-0.044mm 2%; Elemental silicon 0.12-0.044mm 1.1%; Metal aluminum 0.088-0.044mm 0.23%; Organic fiber 0.12%; Water reducing agent 0.15%; It can be seen from the performance test results in Table 1 that, compared with the comparative example, the bulk density and post-firing linear change rate of the embodiment material are increased, the high-temperature flexural strength and the flexural strength retention rate after thermal shock are greatly improved, and the oxidation resistance is significantly improved; the embodiment represents an asphalt-coated aluminum powder castable, and its performance indicators are optimized; blast furnace iron tapping ditch castable is the basis for ensuring the safe, stable and efficient operation of blast furnace iron tapping. Extending the service life of blast furnace iron tapping ditch castable can not only effectively reduce the ironmaking cost and improve production efficiency, but also find a better way to rationally utilize resources; since the iron tapping ditch is frequently subjected to mechanical erosion, corrosion and penetration by high-temperature molten iron and slag, the iron tapping ditch castable must have excellent thermal shock resistance, slag resistance and penetration resistance. The asphalt-coated aluminum powder just satisfactorily solves this problem and greatly improves the service life of the blast furnace iron tapping ditch; therefore, the asphalt-coated aluminum powder iron tapping ditch castable described in the present invention has a good application prospect.

[0015] Table 1 Performance indexes of main channel castables of embodiments and comparative examples

[0016] Note: “A” represents the sample baking temperature of 200℃*24h.

[0017] "B" represents the sample treatment temperature in an oxidizing atmosphere of 1500°C*3h.

[0018] "C" means the sample is baked at 200℃*24h and the strength is tested at 1450℃*1h in a reducing atmosphere.

[0019] “D” means the sample is pre-heated at 1500℃*3h and tested 30 times at 1100℃*0.5h.

[0020] “E” means the sample was pre-treated at 1450℃*3h and then re-treated at 1100℃*5h.

Claims

1. An iron ditch castable of asphalt-coated aluminum powder, characterized in that: The raw material composition, particle size and mass percentage of the material are as follows: Corundum 25-0.044mm 55~62%; Silicon carbide 2.5-0.044mm 17~25%; Alumina powder 5-0.5μm 5~8%; Silicon oxide powder <1μm 0.5~1%; Pure calcium aluminate cement <25μm 1.0~1.5% Andalusite 1-0.12mm 0.2~0.5%; Asphalt coated aluminum powder 1-0.2mm 5~8%; Carbon black <1μm 0.5~1.5%; Organic fiber 0.08-0.12%; Water reducing agent 0.1~0.2%; The asphalt-coated aluminum powder refers to liquid asphalt sprayed with compressed air containing aluminum powder ≤ 0.044 mm, naturally cooled in a cooling tower to form a semi-finished product, and then sieved to obtain solid spherical asphalt that meets the requirements; Mix all the above raw materials evenly, package them, and send them to the iron ditch site for on-site pouring.

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