Blast furnace iron runner skimmer suitable for oscillating sintering and preparation method thereof

Abstract

The application discloses a blast furnace iron runner skimmer suitable for oscillation sintering, and raw material components are as follows in percentage by mass: 18-25% of brown corundum aggregate with a particle size of 5-8 mm; 18-25% of brown corundum aggregate with a particle size of 3-5 mm; 10-18% of brown corundum particles with a particle size of 1-3 mm; 8-15% of dense corundum particles with a particle size of 0.074-1 mm; 5-9% of dense corundum fine powder with a particle size of less than or equal to 0.074 mm; 6-12% of silicon carbide particles with a particle size of 0.074-1 mm; 6-12% of silicon carbide fine powder with a particle size of less than or equal to 0.074 mm; 0.5-3% of spherical pitch with a particle size of 0.1-0.8 mm; 3-6% of submicron SiO2 powder with a particle size of less than or equal to 0.020 mm; 2-7% of alpha-Al2O3 powder with a particle size of less than or equal to 0.020 mm; and 0.5-1.0% of boron oxide powder with a particle size of less than or equal to 0.044 mm. The raw material of the blast furnace iron runner skimmer is well adapted to oscillation sintering through the redesign of the formula, the obtained product has good high-temperature performance, high volume stability, excellent erosion resistance, long service life and low comprehensive operation and maintenance cost, and has remarkable economic and social benefits.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of refractory materials, and particularly relates to a high furnace iron channel skimmer and a preparation method thereof. BACKGROUND

[0002] The iron channel skimmer is an important component of the high furnace iron channel, is located at the tail end of the main channel of the high furnace iron channel, connects the main iron channel, the branch iron channel and the slag channel, and is a key position for separating slag and iron during iron tapping. The iron channel skimmer separates slag and iron through the principle of density difference between slag and iron, and thus needs to withstand chemical corrosion and physical erosion of high-temperature molten slag and molten iron. The damage of the skimmer is often found in the lower half and is often faster than other parts of the main channel. The different service lives of the skimmer and the main channel lead to early shutdown, which will inevitably cause waste of refractory materials and instability and discontinuity of steel production. The service condition of the iron channel skimmer determines the overall service life of the high furnace iron channel and the smooth and efficient operation of the steel industry.

[0003] CN 202010463673.6 discloses a silicon nitride combined castable for a high furnace skimmer and a high furnace skimmer. The technical solution is to introduce silicon nitride powder on the basis of using high-purity raw materials to enhance the density of the castable and thus improve the oxidation resistance, slag resistance and the like of the castable. However, since silicon nitride has good chemical stability at high temperatures, it is difficult to sinter as a whole, which is not conducive to improving the high-temperature service performance. In addition, the introduced cordierite in the raw material will decompose at the service temperature of the skimmer, which will further reduce the high-temperature service performance of the castable.

[0004] CN 202311633692.9 discloses a castable for a high furnace iron channel skimmer. The technical solution is to modify the Al2O3-SiC-C castable by using chromium oxide green and spinel and to realize remote disassembly, maintenance and repair of the skimmer by using a transmission assembly. However, since cement is still used as a binder, the strength of the material at high temperatures cannot be effectively improved, and the problem of easy damage of the skimmer is not fundamentally solved. In addition, due to the introduction of chromium oxide green, toxic hexavalent chromium may be formed under high-temperature oxidation conditions, which also limits the use conditions.

[0005] CN 202010205168.1 discloses a method for online repair of a skimmer. The technical solution is to repair the damaged part of the iron channel skimmer by spraying. However, the complex operations such as lowering the molten iron level and laying a thermal insulation layer are required, and the maintenance time is more than 1 hour. The method has many limitations, cannot fundamentally improve the service performance of the skimmer, and simultaneously affects the normal production operation.

[0006] Oscillating hot-pressing sintering is a new dynamic pressure sintering technology, that is, a clamping pressure with a certain frequency and amplitude is applied in the sintering process, which is beneficial to solve the defects of low density and cracks in the traditional sintering process, and can be applied to the preparation of oxide / non-oxide ceramics and high-temperature alloy products. In the early stage of oscillating sintering, the clamping pressure can promote particle slip, deflection and rearrangement, and eliminate agglomeration; in the later stage of sintering, the clamping pressure can provide greater sintering driving force, stimulate grain boundary slip and plastic deformation, and more effectively promote the merging and discharge of residual closed pores at the grain boundary.

[0007] However, the castables for the iron runner slag skimmer at the present stage are all cement-bound, and the CA6 structure formed after hydration makes the compressive strength of the material after hardening >40MPa. If the traditional cement-bound castables are used to prepare prefabricated parts, the rigidity of the prefabricated parts is too large, and internal microcracks are easy to propagate during the oscillating pressure process, thereby damaging the original structure. Moreover, the particle rearrangement efficiency is low or even no particle rearrangement due to the lack of liquid phase formation under low-temperature conditions of the high-purity raw materials. Therefore, the traditional cement-bound castables are difficult to adapt to the oscillating sintering process. SUMMARY

[0008] The traditional iron runner slag skimmer has the problem of too large rigidity due to cement binding, and the particle rearrangement is hindered under medium and low temperature due to the lack of liquidization conditions, which makes the preparation of the traditional iron runner slag skimmer unable to well adapt to the oscillating sintering system. The present application provides a blast furnace iron runner slag skimmer suitable for oscillating sintering and a preparation method thereof. The raw materials of the blast furnace iron runner slag skimmer are well adapted to the oscillating sintering through the redesign of the formula, and the obtained product has good high-temperature performance, high volume stability, excellent corrosion resistance, long service life and low comprehensive operation and maintenance cost, and the once-through iron capacity of the large and medium-sized blast furnace slag skimmer is improved to 350 to 400 million tons, the service life of the slag skimmer is effectively improved, and significant economic and social benefits are achieved.

[0009] To achieve the above-mentioned purpose, the technical scheme is as follows:

[0010] The raw material composition of the blast furnace iron runner slag skimmer suitable for oscillating sintering is as follows in terms of mass percentage:

[0011] The brown corundum aggregate with a particle size of 5-8mm is 18-25%;

[0012] The brown corundum aggregate with a particle size of 3-5mm is 18-25%;

[0013] The brown corundum particles with a particle size of 1-3mm are 10-18%;

[0014] The dense corundum particles with a particle size of 0.074-1mm are 8-15%;

[0015] The dense corundum fine powder with a particle size of ≤0.074mm is 5-9%.

[0016] Silicon carbide particles with a particle size of 0.074-1mm 6%-12%;

[0017] Silicon carbide fine powder with a particle size of ≤0.074mm 6%-12%;

[0018] Spherical pitch with a particle size of 0.1-0.8mm 0.5%-3%;

[0019] Submicron SiO2 powder with a particle size of ≤0.020mm 3%-6%;

[0020] α-Al2O3 powder with a particle size of ≤0.020mm 2%-7%;

[0021] Boron oxide powder with a particle size of ≤0.044mm 0.5%-1.0%.

[0022] According to the above scheme, the Al2O3 content of the brown corundum is not less than 95.0wt%, the Fe2O3 content is not higher than 0.5wt%, and the C content is not higher than 0.2wt%.

[0023] According to the above scheme, the Al2O3 content of the dense corundum is not less than 99.0wt%, the Fe2O3 content is not higher than 0.2wt%, and the C content is not higher than 0.1wt%.

[0024] According to the above scheme, the SiC content of the silicon carbide is not less than 98.0wt%.

[0025] According to the above scheme, the C content of the spherical pitch is not less than 55.0wt%.

[0026] According to the above scheme, the SiO2 content of the submicron SiO2 powder is not less than 99.8wt%, and the D 90 is not higher than 3μm.

[0027] According to the above scheme, the Al2O3 content of the α-Al2O3 powder is not less than 99.5wt%, and the D 50 is not higher than 5μm.

[0028] According to the above scheme, the B2O3 content of the boron oxide powder is not less than 99.9wt%, and the D 50 is not higher than 25μm.

[0029] The above method for preparing the blast furnace iron runner skimmer suitable for oscillation sintering comprises the following steps:

[0030] (1) After mixing the raw materials, 3%-5% of water is added and mixed uniformly, and then the precast piece is obtained by pouring and vibration forming;

[0031] (2) one-stage oscillation sintering: heating at 4-5 ℃ / min to 1100-1150 ℃ at room temperature, and during the process, the preform is clamped and oscillated when the temperature is raised to 500-550 ℃, wherein the clamping pressure is 2-5 MPa, and the oscillation frequency is 2-4 Hz;

[0032] (3) two-stage oscillation sintering: continue to heat at 2-3 ℃ / min to 1350-1370 ℃, and at the same time, the preform is clamped and oscillated, wherein the clamping pressure is 5-8 MPa, and the oscillation frequency is 4-5 Hz.

[0033] According to the above scheme, the clamping pressure application direction is consistent with the oscillation direction.

[0034] Compared with the prior art, the present application has the following advantages:

[0035] The present application changes the original cement bonding system of castable and uses sub-micron SiO2 micro powder for bonding, and the Si-O-Si bond formed thereby can be broken and reorganized during oscillation, and the sub-micron SiO2 micro powder can more effectively fill the pores, effectively solving the problem of excessive rigidity of CA6 formed by traditional cement bonding and excessive internal pore structure not suitable for oscillation sintering.

[0036] By introducing boron oxide powder, the present application takes advantage of the low-temperature liquefaction (liquefaction temperature <500 ℃) characteristics of boron oxide powder to form an appropriate amount of liquid phase, thereby improving the particle rearrangement rate and effect of one-stage oscillation sintering and accelerating the densification process.

[0037] The present application develops the synergistic effect of sub-micron SiO2 micro powder and boron oxide powder in oscillation sintering. Under the conditions of oscillation and pressure at medium temperature, high-activity sub-micron SiO2 micro powder initiates mullitization reaction in advance, and boron oxide liquid phase is solid-soluted in the mullite phase, forming a high-strength / high-aspect-ratio boron-doped mullite network structure, avoiding the residual of excess liquid phase and the formation of aluminum borate phase, and ensuring the volume stability of the preform and improving the high-temperature performance.

[0038] In the one-stage oscillation sintering process, the present application adopts the mode of low-temperature rapid heating, small pressure, and low oscillation frequency, which is beneficial to optimizing the quality and effect of particle rearrangement by oscillation sintering; in the two-stage oscillation sintering process, the mode of slow heating, large pressure, and high oscillation frequency is used at high temperature to accelerate the development and growth of boron-doped mullite, and improve the high-temperature performance.

[0039] Through the redesign of the formula, the present application makes the raw materials of the blast furnace iron runner skimmer well adapted to oscillation sintering, and the volume change rate of the obtained product during service is-0.1% to 0.1%, the cold modulus of rupture is not less than 20.0 MPa, the high-temperature modulus of rupture is not less than 15.0 MPa, the corrosion index is not higher than 0.10, the main service life is more than 180 days, and the comprehensive operation and maintenance cost is reduced by more than 20%. DETAILED DESCRIPTION

[0040] The following examples further illustrate the technical solutions of the present invention but are not intended to limit the scope of protection of the present invention.

[0041] In a specific embodiment, the Al2O3 content of the selected brown corundum is 95.2%, the Fe2O3 content is 0.14%, and the C content is 0.07%; the Al2O3 content of the dense corundum is 99.1%, the Fe2O3 content is 0.11%, and the C content is 0.05%; the SiO2 content of the submicron SiO2 powder is 99.9%, and the D 90 1.8μm; Al2O3 content in α-Al2O3 powder is 99.6%, D 50 The B2O3 content in the boron oxide powder is 99.9%, D 50 Unless otherwise specified, all raw materials were purchased from the market.

[0042] Example 1

[0043] The raw materials and contents of the iron ditch skimmer are: 24.5% brown corundum aggregate with a particle size of 5-8mm, 18% brown corundum aggregate with a particle size of 3-5mm, 10% brown corundum particles with a particle size of 1-3mm, 12% dense corundum particles with a particle size of 0.074-1mm, 9% dense corundum fine powder with a particle size of ≤0.074mm, 6% silicon carbide particles with a particle size of 0.074-1mm, 12% silicon carbide fine powder with a particle size of ≤0.074mm, 3% spherical asphalt with a particle size of 0.1-0.8mm, 3% submicron SiO2 fine powder with a particle size of ≤0.020mm, 2% α-Al2O3 fine powder with a particle size of ≤0.020mm, and 0.5% boron oxide powder with a particle size of ≤0.044mm.

[0044] The preparation method of the oscillating sintering blast furnace iron ditch slag skimmer is as follows: (1) mixing the raw materials until uniform, adding 3.0% water and continuing to stir and mix for 3 minutes, and casting and vibrating to form a prefabricated part; (2) casting the prefabricated part and sintering it into a finished part through oscillation; (3) casting and embedding the finished skimmer part in the corresponding position of the iron ditch main ditch on site to start service.

[0045] One-stage oscillation sintering: the heating rate is 4.0°C / min, the preform is clamped and oscillated when the temperature reaches 500°C, and the end temperature is 1100°C; the clamping pressure is 2 MPa and the oscillation frequency is 2 Hz.

[0046] Second stage oscillation sintering: continue to heat up to 1350°C at a rate of 2.0°C / min, while clamping the preform and oscillating it, with a clamping pressure of 5 MPa and an oscillation frequency of 4 Hz.

[0047] Example 2

[0048] The raw materials and their contents of the iron runner skimmer are as follows: brown corundum aggregate with a particle size of 5-8 mm 18%, brown corundum aggregate with a particle size of 3-5 mm 25%, brown corundum particles with a particle size of 1-3 mm 18%, dense corundum particles with a particle size of 0.074-1 mm 8%, dense corundum fine powder with a particle size of ≤0.074 mm 5%, silicon carbide particles with a particle size of 0.074-1 mm 10%, silicon carbide fine powder with a particle size of ≤0.074 mm 6%, spherical pitch with a particle size of 0.1-0.8 mm 1.3%, submicron SiO2micropowder with a particle size of ≤0.020 mm 6%, α-Al2O3micropowder with a particle size of ≤0.020 mm 2%, and boron oxide powder with a particle size of ≤0.044 mm 0.7%.

[0049] The preparation method of the oscillation sintering blast furnace iron runner skimmer is as follows: (1) the raw materials are mixed uniformly, 5.0% of water is added and the mixture is continuously stirred for 5 min, and then the mixture is poured and vibrated to form a preform; (2) the poured preform is sintered by oscillation to form a finished product; and (3) the finished product of the skimmer is poured and inlaid at a corresponding position of the main runner of the iron runner to start service.

[0050] One-stage oscillation sintering: the preform is clamped and oscillated when the temperature is raised to 520℃ at a rate of 4.5℃ / min, and the end temperature is 1110℃; wherein the clamping pressure is 2.5 MPa and the oscillation frequency is 3 Hz.

[0051] Two-stage oscillation sintering: the temperature is continuously raised to 1355℃ at a rate of 2.5℃ / min, and the preform is clamped and oscillated at the same time, the clamping pressure is 6 MPa and the oscillation frequency is 5 Hz.

[0052] Example 3

[0053] The raw materials and their contents of the iron runner skimmer are as follows: brown corundum aggregate with a particle size of 5-8 mm 20%, brown corundum aggregate with a particle size of 3-5 mm 20%, brown corundum particles with a particle size of 1-3 mm 12.7%, dense corundum particles with a particle size of 0.074-1 mm 15%, dense corundum fine powder with a particle size of ≤0.074 mm 6%, silicon carbide particles with a particle size of 0.074-1 mm 7%, silicon carbide fine powder with a particle size of ≤0.074 mm 7%, spherical pitch with a particle size of 0.1-0.8 mm 1.5%, submicron SiO2micropowder with a particle size of ≤0.020 mm 5%, α-Al2O3micropowder with a particle size of ≤0.020 mm 5%, and boron oxide powder with a particle size of ≤0.044 mm 0.8%.

[0054] The preparation method of the oscillation sintering blast furnace iron runner skimmer is: (1) the raw materials are mixed uniformly, 4.0% of water is added and continues to be stirred and mixed for 4 minutes, and then precast is formed by pouring and vibration; (2) the precast is sintered by oscillation to form a finished product; and (3) the finished product of the skimmer is poured and inlaid at the corresponding position of the main runner of the iron runner to start service.

[0055] One-stage oscillation sintering: the temperature is raised at a rate of 5.0 ℃ / min, the precast is clamped and oscillated when the temperature is raised to 550 ℃, and the end temperature is 1150 ℃; wherein the clamping pressure is 5.0 MPa and the oscillation frequency is 4 Hz.

[0056] Two-stage oscillation sintering: the temperature is continuously raised at a rate of 3.0 ℃ / min to 1360 ℃, the precast is clamped and oscillated at the same time, the clamping pressure is 7 MPa and the oscillation frequency is 4 Hz.

[0057] Example 4

[0058] The raw materials and their contents of the iron runner skimmer are: 25% of brown corundum aggregate with a particle size of 5-8 mm, 18% of brown corundum aggregate with a particle size of 3-5 mm, 10% of brown corundum particles with a particle size of 1-3 mm, 10% of dense corundum particles with a particle size of 0.074-1 mm, 6.5% of dense corundum fine powder with a particle size of ≤0.074 mm, 12% of silicon carbide particles with a particle size of 0.074-1 mm, 6% of silicon carbide fine powder with a particle size of ≤0.074 mm, 0.5% of spherical pitch with a particle size of 0.1-0.8 mm, 4% of submicron SiO2micropowder with a particle size of ≤0.020 mm, 7% of α-Al2O3micropowder with a particle size of ≤0.020 mm, and 1.0% of boron oxide powder with a particle size of ≤0.044 mm.

[0059] The preparation method of the oscillation sintering blast furnace iron runner skimmer is: (1) the raw materials are mixed uniformly, 3.5% of water is added and continues to be stirred and mixed for 4 minutes, and then precast is formed by pouring and vibration; (2) the precast is sintered by oscillation to form a finished product; and (3) the finished product of the skimmer is poured and inlaid at the corresponding position of the main runner of the iron runner to start service.

[0060] One-stage oscillation sintering: the temperature is raised at a rate of 4.0 ℃ / min, the precast is clamped and oscillated when the temperature is raised to 540 ℃, and the end temperature is 1150 ℃; wherein the clamping pressure is 4.0 MPa and the oscillation frequency is 3 Hz.

[0061] Two-stage oscillation sintering: the temperature is continuously raised at a rate of 2.0 ℃ / min to 1370 ℃, the precast is clamped and oscillated at the same time, the clamping pressure is 8 MPa and the oscillation frequency is 5 Hz.

[0062] Comparative Example 1

[0063] Example 1 was repeated, and the sub-micron SiO2 powder with a particle size of ≤0.020 mm in the formulation was replaced with aluminate cement, and the amount was unchanged.

[0064] Comparative Example 2

[0065] Example 1 was repeated, and the boron oxide powder with a particle size of ≤0.044 mm in the formulation was replaced with α-Al2O3 powder with a particle size of ≤0.020 mm, and the amount was unchanged.

[0066] Comparative Example 3

[0067] Example 1 was repeated, and the same temperature rising sintering method was used, but the clamping and oscillation were cancelled.

[0068] Comparative Example 4

[0069] Example 1 was repeated, and one-time oscillation sintering was used: the temperature was directly raised to 1350°C at a temperature rising rate of 4.0°C / min, and the preform was clamped and oscillated when the temperature rose to 500°C; wherein the clamping pressure was 2 MPa, and the oscillation frequency was 2 Hz.

[0070] The permanent linear change rate of the finished product 1450°C x 3h was determined by the method in GB / T 5988-2022, the cold modulus of rupture after heat treatment of the finished product 1450°C x 3h was determined by the method in GB / T 3001-2017, the high temperature modulus of rupture of the castable 1400°C x 1h was determined by the method in GB / T 3002-2017, and the slag iron erosion resistance was determined by the method in GB / T 8931-2007 (static crucible method). The properties of each example and each comparative example were compared, and the details are shown in Table 1.

[0071] Table 1

[0072]

[0073] In Comparative Example 1, aluminate cement was used as the binder, which caused the preform to have too much rigidity, and the internal microcracks were easily extended during the oscillation and pressure process, which damaged the original structure. In addition, CaO in the cement was converted into liquid phase at high temperature, which significantly reduced the high temperature strength.

[0074] In Comparative Example 2, α-Al2O3 powder was used to replace boron oxide powder, which significantly reduced the particle rearrangement and densification efficiency during low temperature oscillation sintering, and could not adapt to the oscillation sintering process.

[0075] In Comparative Example 3, the pre-sintering treatment method was used, and the lack of clamping pressure and oscillation significantly reduced the sintering densification degree of the preform. In the case of increasing the process flow compared with the traditional method, the performance and use effect were not obviously improved, and the comprehensive cost was not significantly different.

[0076] The non-staged oscillatory sintering in Comparative Example 4 did not rearrange the particles completely and boron-doped mullitization was not complete, resulting in failure to fully play the effect of oscillatory sintering, and the performance and use effect were lower than those of Example 1.

[0077] The above examples are merely intended for the purpose of illustration, and are not intended to limit the embodiments. Based on the above description, those skilled in the art can make other different forms of changes or modifications, and here it is not necessary or possible to exhaust all the embodiments, and thus the obvious changes or modifications derived are still within the protection scope of the present application.

Claims

1. A method of preparing a trough skimmer for a blast furnace suitable for oscillating sintering, characterised in that The method comprises the following steps: (1) mixing raw materials, adding 3-5% water, and uniformly mixing to obtain a preform; (2) one-stage oscillation sintering: heating at 4-5 ℃ / min to 1100-1150 ℃ at room temperature, and clamping the preform and oscillating when the temperature is raised to 500-550 ℃, wherein the clamping pressure is 2-5 MPa and the oscillation frequency is 2-4 Hz; (3) two-stage oscillation sintering: continuing to heat at 2-3 ℃ / min to 1350-1370 ℃, while clamping the preform and oscillating, wherein the clamping pressure is 5-8 MPa and the oscillation frequency is 4-5 Hz. The raw material composition of the blast furnace iron runner skimmer is as follows in terms of mass percentage: 18-25% brown corundum aggregate with a particle size of 5-8 mm; 18-25% brown corundum aggregate with a particle size of 3-5 mm; 10-18% brown corundum particles with a particle size of 1-3 mm; 8-15% dense corundum particles with a particle size of 0.074-1 mm; 5-9% dense corundum fine powder with a particle size of ≤0.074 mm; 6-12% silicon carbide particles with a particle size of 0.074-1 mm; 6-12% silicon carbide fine powder with a particle size of ≤0.074 mm; 0.5-3% spherical pitch with a particle size of 0.1-0.8 mm; 3-6% submicron SiO2 powder with a particle size of ≤0.020 mm; 2-7% α-Al2O3 powder with a particle size of ≤0.020 mm; 0.5-1.0% boron oxide powder with a particle size of ≤0.044 mm.

2. The method of claim 1, wherein the iron runner skimmer for a blast furnace adapted for oscillating sintering is characterized by The Al2O3 content of the brown corundum is not less than 95.0 wt%, the Fe2O3 content is not higher than 0.5 wt%, and the C content is not higher than 0.2 wt%.

3. The method of claim 1, wherein the iron runner skimmer for a blast furnace adapted for oscillating sintering is characterized by The Al2O3 content of the dense corundum is not less than 99.0 wt%, the Fe2O3 content is not higher than 0.2 wt%, and the C content is not higher than 0.1 wt%.

4. The method of claim 1, wherein the iron runner skimmer for a blast furnace adapted for oscillating sintering is characterized by The SiC content of the silicon carbide is not less than 98.0 wt%.

5. The method of claim 1, wherein the iron runner skimmer for a blast furnace adapted for oscillating sintering is characterized by The C content of the spherical pitch is not less than 55.0 wt%.

6. The method of claim 1, wherein the iron runner skimmer for a blast furnace adapted for oscillating sintering is characterized by The SiO2 content of the submicron SiO2 powder is not less than 99.8wt%, D 90 not more than 3 μm.

7. The method of claim 1, wherein the method is used for the preparation of a trough skimmer for a blast furnace suitable for oscillating sintering, characterized in that The α-Al2O3 micropowder has an Al2O3 content of not less than 99.5 wt%, D 50 not more than 5 μm.

8. The method of claim 1, wherein the method is used for the preparation of a trough skimmer for a blast furnace adapted for oscillating sintering. The B2O3 content of the boron oxide powder is not less than 99.9wt%, D 50 not more than 25 μm.

9. The method of claim 1, wherein the method is used for the preparation of a trough skimmer for a blast furnace suitable for oscillating sintering, characterized in that The clamping pressure application direction is consistent with the oscillation direction.

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