Aluminum killed steel ladle top slag modifier and preparation method thereof

Abstract

The invention provides an aluminum killed steel ladle top slag modifier which comprises the following components in percentage by weight: 50-60% of aluminum particles, 5-10% of carbon powder, 15-25% of active lime, 3-7% of borocalcite, 3-7% of szaibelyite and 2-3% of a binder, and the total proportion of the borocalcite and the szaibelyite does not exceed 10%. The preparation method of the top slag modifier comprises the following steps: S1, respectively crushing and drying szaibelyite, borocalcite and active lime, and then uniformly mixing with aluminum particles, carbon powder and a binder; s2, carrying out ball pressing granulation on the mixed raw material by adopting a ball pressing machine; and S3, carrying out baking treatment on the ball pressing product, and carrying out sealed packaging. According to the invention, through reasonable components and dosage, after the slag-containing additive is added into molten steel, the adsorption capacity of slag to inclusions in aluminum killed steel can be effectively improved, the density of the inclusions in the aluminum killed steel is controlled within 10.5 / mm < 2 >, the total oxygen in the steel is controlled below 9 * 10 <-6 >, the fluidity of the slag liquid is improved, and the corrosion of the steel slag to a steel ladle slag line is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of steelmaking, and in particular to an aluminum killed steel ladle top slag modifier and a preparation method thereof. Background Art

[0002] Low-carbon aluminum-killed steel is a special type of steel with a low carbon content and aluminum alloying. This steel has excellent mechanical properties and is widely used in the automotive, construction, shipbuilding, petrochemical and other industries. When smelting low-carbon aluminum-killed steel in a converter, it is necessary to boil the steel due to the need for decarbonization. At this time, the oxygen content in the steel is high and the Fe content in the slag is x The sum of O and MnO content is 20% to 30%. Highly oxidizing slag affects the alloy recovery rate and increases the burden of later molten steel deoxidation. In order to reduce the secondary pollution of molten steel by highly oxidizing slag, steel companies often use top slag modifiers to reduce the oxidizing property of slag and realize the recovery of metal resources in ladle slag.

[0003] Inclusions in aluminum-killed steel are mostly Al2O3, and a large amount of Al2O3 agglomerates and floats. Suitable refined slag needs to have a good adsorption capacity for such inclusions. It is generally believed that a higher Al2O3 saturation concentration difference and a lower slag viscosity are important factors that are conducive to the adsorption of such inclusions.

[0004] At present, there are many ladle modifiers, which are basically aluminum-based modifiers. For example, Chinese patent CN114737025A discloses a RH top slag modifier and its preparation method, which has the following components: Al: 10-45%; Al2O3: 10-35%; CaO: 15-30%; MgO: 3-10%; and does not contain CaF2 and CaCO3. Among them, the sum of the mass percentages of Al and Al2O3 is greater than 40% and less than 70%, and the mass ratio of Al to Al2O3 is 1: (0.4 0.7). The modifier adjusts the slag properties of the slag in the ladle by not containing CaF2 and CaCO3 modifiers, effectively reduces the FeO content in the slag, has a strong ability to absorb molten steel inclusions, improves the purity of molten steel, and forms the characteristics of low-melting-point ladle top slag. After modification, the surface tension of the slag liquid increases, and the inclusions in the molten steel can be quickly adhered to, which has a good slag turning effect and solves the comprehensive problem of removing inclusions. However, the modifier does not contain CaF2. In order to ensure the fluidity of the modified slag, a higher Al2O3 content is required in the slag system. The high Al2O3 content in the refined slag will affect the slag's adsorption of Al2O3, a typical inclusion in steel, and may even seep back into the molten steel. The increase in the Al2O3 content in the molten steel will cause cracks in the billet rolling process.

[0005] Chinese patent CN106119462A discloses an Al-based ladle top slag modifier, comprising the following components in mass percentage: Al, 40% to 60%; CaCO3, 20% to 50%; Al2O3, 2% to 10%; SiO2, 1% to 5%; water and inevitable impurities, 0.2% to 5%; three groups of calcium carbonate with different particle sizes are added to the modifier, wherein the particle size of the calcium carbonate in group M1 is 4 to 6 mm, the particle size of the calcium carbonate in group M2 is 2 to 4 mm, and the particle size of the calcium carbonate in group M3 is 0.1 to 2 mm, and the mass ratio of the three groups of calcium carbonate is group M1: group M2: group M3 = (4.5 to 5.5): (2.5 to 3.5): (1.5 to 2.2). In this modifier, the CO2 generated by the decomposition of calcium carbonate will isolate the Al in the modifier from the air, which can prevent the Al in the modifier from combining with oxygen in the air and improve the utilization efficiency, action time and basicity of Al. However, from the perspective of composition, this modifier does not consider the effect of its effect on slag fluidity, and its addition may cause the fluidity of steel slag to deteriorate.

[0006] Chinese patent CN115287408B discloses a high manganese steel ladle top slag modifier and preparation method. The raw material composition is calculated by weight percentage: metal magnesium particles: 3% to 5%; aluminum wire: 10% to 25%; active lime: 40% to 60%; boric anhydride stone: 5% to 10%; wollastonite: 12% to 30%. The modifier of the invention has a good ability to reduce the oxidizing properties of MnO and other substances in the slag, stabilize the fluctuation of manganese components in steel, and has the ability to adjust the fluidity of the slag. However, due to the presence of metal magnesium, magnesium is easy to volatilize, resulting in a low magnesium yield, and it is easy to cause the modified balls to burst into powder and not easy to sink into the slag, reducing the reducibility of the modifier; and 12% to 30% wollastonite in the modifier component will significantly reduce the basicity of the slag. For aluminum-killed steel that requires high basicity slag (R>5), its basicity and the calcium-aluminum ratio are not suitable for the adsorption and removal of typical Al2O3 slag inclusions in aluminum-killed steel.

[0007] See also Figure 1 According to calculations, the best low-carbon, low-silicon, aluminum-killed steel slag system is Figure 1 The medium alkalinity R>5, and the fluidity is near the 1400℃ liquid phase region. Comprehensive development of a modifier that has both good fluidity and Al2O3 inclusion adsorption capacity, and low corrosion to the furnace lining, has a good application value for ladle modification and aluminum-killed steel production. Summary of the invention

[0008] The object of the present invention is to provide an aluminum killed steel ladle top slag modifier and a preparation method thereof in view of the drawbacks of the prior art.

[0009] The technical solution adopted by the present invention to solve its technical problem is:

[0010] A modifier for aluminum-killed steel ladle top slag comprises the following components in weight percentage: 50% to 60% aluminum particles, 5% to 10% carbon powder, 15% to 25% active lime, 3% to 7% colemanite, 3% to 7% magnesite, and 2% to 3% binder, wherein the total proportion of colemanite and magnesite does not exceed 10%.

[0011] Preferably, the aluminum-killed steel ladle top slag modifier contains the following components in weight percentage: 52% to 58% aluminum particles, 5% to 8% carbon powder, 20% to 25% active lime, 3% to 5% colemanite, 4% to 7% boraxite, and 2% to 3% binder, wherein the total proportion of colemanite and boraxite does not exceed 10%.

[0012] The aluminum content in the aluminum particles is greater than 98%; the binder is bentonite; the activity of the active lime is greater than 330ml / 4N-HCI, and the CaO content is greater than 85%.

[0013] The preparation method of the aluminum killed steel ladle top slag modifier comprises the following steps:

[0014] S1, crushing and drying boraxite, colemanite and active lime respectively, and then uniformly mixing the dried boraxite, colemanite, active lime, aluminum particles, carbon powder and binder;

[0015] S2, using a ball press to granulate the mixed raw materials;

[0016] S3. Bake the pressed balls and pack them in sealed packages.

[0017] In the step S1, boraxite, colemanite, active lime, aluminum particles and carbon powder are first mixed uniformly, and then a binder is added to the mixture and mixed uniformly. The boraxite and colemanite have a crushed particle size of 0.3 to 2.0 mm, the active lime has a crushed particle size of 0.3 to 1 mm, the aluminum particles have a particle size of less than 5 mm, and the carbon powder has a particle size of less than 1 mm.

[0018] In the step S2, the mixed raw materials are pressed into material balls with a particle size of 20 to 40 mm using a ball press.

[0019] In step S3, the baking temperature is controlled at 50-100° C., and the baking time is 6-10 hours.

[0020] Through the above technical solution, the beneficial effects obtained by the present invention are:

[0021] The present invention discloses a top slag modifier for aluminum-killed steel ladle. Through reasonable components and dosage, after adding the top slag modifier to molten steel, the slag can effectively improve the adsorption capacity of the slag to the inclusions in the aluminum-killed steel, improve the fluidity of the slag liquid, and reduce the erosion of the slag line of the ladle. By using the top slag modifier of the present invention, the adsorption capacity of the ladle slag to the Al2O3 inclusions in the steel is improved by more than 15%, and the unit density of the inclusions in the steel is reduced by 3 / mm compared with that without adding the modifier. 2 After modification, the inclusion density in aluminum-killed steel is controlled at 10.5 / mm 2 The total oxygen in the steel is controlled within 9×10 -6 Following this, the quality of aluminum killed steel has steadily improved.

[0022] The invention uses strong reduction of aluminum and Fe in the top slag to x O and MnO undergo a rapid redox reaction, recovering Fe and Mn into the molten steel; by adding a small amount of carbon powder to replace aluminum particles for deoxidation, without or with little Al2O3 powder, the Al2O3 content in the slag can be reduced, which is beneficial to improving the saturation concentration difference of Al2O3 in the slag, and then improving the slag's adsorption capacity for Al2O3 inclusions in the steel. Adding a small amount of colemanite and magnesite, the B2O3 decomposed from these two substances can significantly reduce the melting point of the slag system and improve the fluidity of the slag, and these two substances are more economical than pure B2O3; finally, the CaO and MgO decomposed from colemanite and magnesite can increase the slag basicity and MgO content, which has the effect of protecting the furnace lining.

[0023] The present invention can effectively slow down the corrosion of the ladle lining by steel slag and prolong the service life of the ladle lining by 8 to 10 furnaces; at the same time, since the Al2O3 inclusions in the molten steel are reduced, the blockage of the tundish water outlet during casting is greatly reduced, thereby accelerating the production rhythm.

[0024] The system of the present invention does not contain fluorine, thus greatly reducing the pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Aluminum killed steel CaO-SiO2-Al2O 3- Superposition diagram of liquidus lines, oxygen lines and sulfur lines in MgO-FeO slag system slag-steel equilibrium. DETAILED DESCRIPTION

[0026] The present invention is described in further detail below.

[0027] The present invention provides an aluminum-killed steel ladle top slag modifier, comprising the following components in weight percentage: 50% to 60% of aluminum particles, 5% to 10% of carbon powder, 15% to 25% of active lime, 3% to 7% of colemanite, 3% to 7% of magnesite, and 2% to 3% of binder, wherein the total proportion of colemanite and magnesite does not exceed 10%.

[0028] Preferably, the aluminum-killed steel ladle top slag modifier contains the following components in weight percentage: aluminum particles: 52% to 58%, carbon powder 5% to 8%, active lime 20% to 25%, colemanite 3% to 5%, magnesite 4% to 7%, and binder 2% to 3%, wherein the total proportion of colemanite and magnesite does not exceed 10%.

[0029] Further preferably, the aluminum-killed steel ladle top slag modifier comprises the following components in weight percentage: 60% aluminum particles, 8% carbon powder, 20% active lime, 5% colemanite, 4% boraxite, and 3% binder.

[0030] The main component of the converter lining refractory brick is Mg-C. Once MgO melts into the slag, it will cause erosion of the brick body; therefore, a modifier is needed to provide sufficient Mg content to increase the Mg content in the slag and prevent the Mg in the refractory brick from being dissolved. Since the MgO content in each batch of ladle slag will fluctuate, the amount of boraxite is adjusted with the MgO content in the ladle slag. Generally speaking, the MgO content in most CaO-SiO2-MgO-Al2O3-FeO five-element converter slag systems is between 2% and 6%. In order to prevent the MgO in the slag from being too high and affecting the fluidity of the ladle slag, the content of boraxite is controlled at 3-7%. About 5% of boron oxide can reduce the melting point of the slag, so the total proportion of boraxite + boraxite does not exceed 10%.

[0031] The aluminum content in the aluminum particles is greater than 98%, and the binder is bentonite.

[0032] The activity of the active lime is greater than 330 ml / 4N-HCl, and the CaO content is greater than 85%.

[0033] In the modifier of the present invention, aluminum particles are strong deoxidizers, which are used to reduce Fe in the slag during top slag modification. x O and MnO, reducing the oxidizability of the slag. The role of carbon powder is also to reduce Fe in the slag xO and MnO, and the CO gas produced by the reaction can form a gas protection layer on the slag surface, reducing the proportion of aluminum particles directly oxidized by air; at the same time, using carbon powder instead of aluminum particles as a reducing agent can reduce the amount of aluminum used, reduce the proportion of Al2O3 in the slag, and then increase the saturation concentration difference of Al2O3 in the slag, and enhance the slag's adsorption capacity for Al2O3 inclusions in steel. The role of active lime is to increase the basicity of the slag, which is beneficial to the desulfurization and dephosphorization of molten steel. Boronite and boraxite decompose B2O3 in high-temperature slag. The presence of B2O3 can significantly reduce the viscosity of the slag, improve the fluidity of the slag liquid, and is conducive to the adsorption of Al2O3 inclusions in the steel by the slag; and the price of Boronite and boraxite is relatively cheap compared to B2O3. The MgO decomposed by them at the same time can increase the MgO content in the slag, which has a protective effect on the ladle lining; and using part of Boronite to replace boraxite, the B2O3 decomposed by Boronite can not only ensure the B2O3 content in the slag, but also improve the basicity of the slag by decomposing CaO, and prevent the MgO in the slag from being too high, which affects the fluidity of the slag. The binder has the effect of bonding various materials, which is convenient for ball pressing.

[0034] It can be seen from the above description that in the modifier of the present invention, the various components are not relatively independent, but there is a relationship of mutual influence and mutual restriction. The relative amount of aluminum particles and carbon powder is related to the content of Al2O3 in the slag, thereby affecting the adsorption capacity of steel slag to Al2O3. Boron magnesium stone and boraxite jointly provide boron elements to reduce the melting point of steel slag and improve the fluidity of steel slag. However, if the total amount of boraxite and boraxite is too large and the B2O3 content in the steel slag is too high, the steel slag will be too thin, which will affect the adsorption of Al2O3 by the slag, which is not conducive to the control of inclusions in steel. Boron magnesium stone and boraxite are not only constrained by the total amount, but also by their independent effects. For example, the amount of boraxite affects the Mg content in the slag. If the amount of boraxite is too high, the Mg content in the slag will increase, causing the slag to become viscous and the fluidity to deteriorate; if the amount of boraxite is too low, the Mg content in the slag is low, which will cause the steel slag to corrode the ladle lining. Appropriate colemanite content can control the basicity of the slag within a suitable range to ensure the absorption of Al2O3. Therefore, based on the specific requirements of aluminum-killed steel for the composition of molten steel, the present invention makes detailed restrictions on the dosage of each component of the modifier, and adopts the weight percentage as a mutually influential restriction method. The adjustment range of the content of each component is small, and within this range, it can fully ensure that each component effectively cooperates and enhances each other, and finally achieves effective modification of the aluminum-killed steel ladle top slag, fully adsorbs Al2O3 in the molten steel, and controls the inclusion density in the aluminum-killed steel to 10.5 pieces / mm 2 Within.

[0035] Generally speaking, the dosage of the top slag modifier of the present invention is 100-200 kg / t slag.

[0036] The preparation method of the aluminum killed steel ladle top slag modifier comprises the following steps:

[0037] S1, crushing and drying boraxite, colemanite and active lime respectively, and then uniformly mixing the dried boraxite, colemanite, active lime, aluminum particles, carbon powder and binder;

[0038] S2, using a ball press to granulate the mixed raw materials;

[0039] S3. Bake the pressed balls and pack them in sealed packages.

[0040] In the step S1, borax, colemanite, active lime, aluminum particles and carbon powder are firstly mixed evenly, and then a binder is added to the mixture and mixed evenly.

[0041] The crushed particle size of the boraxite and colemanite is 0.3-2.0 mm, the crushed particle size of the active lime is 0.3-1 mm, the particle size of the aluminum particles is less than 5 mm, and the particle size of the carbon powder is less than 1 mm.

[0042] In the step S2, the mixed raw materials are pressed into material balls with a particle size of 20 to 40 mm using a ball press.

[0043] In step S3, the baking temperature is controlled at 50-100° C., and the baking time is 6-10 hours.

[0044] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments and comparative examples. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Example 1

[0046] The invention discloses an aluminum-killed steel ladle top slag modifier, the raw materials of which are as follows (by weight percentage): 60% aluminum particles, 8% carbon powder, 20% active lime, 5% colemanite, 4% boraxite and 3% bentonite.

[0047] The preparation method of the aluminum killed steel ladle top slag modifier comprises the following steps:

[0048] S1. Crush magnesite and colemanite into powders of 0.3-2.0 mm respectively and bake at 120°C for 3 hours; crush active lime into powders of 0.3-1 mm and bake at 300°C for 2 hours; crush carbon powder into powders of less than 1 mm; control aluminum particles containing more than 98% aluminum within 5 mm;

[0049] The crushed boraxite, colemanite, active lime, carbon powder and aluminum particles are mixed evenly, and bentonite is added to the mixed materials, and mixed evenly again to make them bonded;

[0050] S2. Press the material into material balls with a diameter of 20 to 40 mm through a ball press;

[0051] S3. Bake the pressed material balls at 80° C. for 8 hours, and seal and package the material balls in a dry environment.

[0052] Example 2

[0053] The invention discloses an aluminum killed steel ladle top slag modifier, the raw materials of which are as follows (by weight percentage): 52% aluminum particles, 10% carbon powder, 25% active lime, 3% colemanite, 7% boraxite and 3% bentonite.

[0054] The preparation method of the aluminum killed steel ladle top slag modifier is exactly the same as that in Example 1.

[0055] Example 3

[0056] The invention discloses an aluminum killed steel ladle top slag modifier, the raw materials of which are as follows (by weight percentage): 58% aluminum particles, 5% carbon powder, 25% active lime, 5% colemanite, 5% boraxite and 2% bentonite.

[0057] The preparation method of the aluminum killed steel ladle top slag modifier is exactly the same as that in Example 1.

[0058] The modifiers prepared in Examples 1 to 3 were used in the aluminum killed steel smelting site of Delong Steel Plant for testing. The specific process was as follows:

[0059] 97.2 tons of molten steel was tapped from the converter. 400 kg of lime and 100 kg of ladle top slag modifier were added to the ladle during tapping. 80 kg of aluminum ingots and 70 kg of medium carbon ferromanganese were added after 1 / 2 of the steel was tapped. 28.73 kg of aluminum wire was fed to the ladle with argon. Samples of converter slag, ladle slag after argon, and steel from the argon outlet station were taken for testing.

[0060] Table 1 Composition of converter slag and post-argon ladle slag in Example 1

[0061]

[0062] The steel sample was taken out from the argon station for testing and found that the total oxygen in the steel was 8.5×10 -6 , inclusion density 9.8 pieces / mm 2 Under the same production conditions, the ladle lining can be used for 51 furnaces.

[0063] Table 2 Composition of converter slag and post-argon ladle slag in Example 2

[0064]

[0065] The steel sample was taken out from the argon station for testing and found that the total oxygen in the steel was 8.7×10-6 , inclusion density 10.0 pieces / mm 2 Under the same production conditions, the ladle lining can be used for 51 furnaces.

[0066] Table 3 Composition of converter slag and post-argon ladle slag in Example 3

[0067]

[0068] The steel sample was taken out of the argon station for testing and found that the total oxygen in the steel was 8.8×10 -6 , inclusion density 10.2 pieces / mm 2 Under the same production conditions, the ladle lining can be used for 50 furnaces.

[0069] It can be seen from the above experimental data that after using the top slag modifier of the present invention, the Al2O3 content in the ladle slag after argon is greatly increased, and the inclusion density in the steel sample is controlled at 10.5 / mm 2 The following proves that the use of the steel slag modifier of the present invention effectively improves the adsorption performance of the slag to Al2O3, and most of the Al2O3 in the molten steel is adsorbed by the slag; the Al2O3 content in the slag is about 25%, and the fluidity of the slag is moderate.

[0070] The TFe content and FeO content in the ladle slag after argon treatment dropped significantly, proving that most of the Fe component in the slag was recovered into the molten steel, with a high metal recovery rate; at the same time, the total oxygen content in the steel sample leaving the argon station was low, reducing the burden of deoxidation of the molten steel in the later stage.

[0071] After adopting the top slag modifier of the present invention, the service life of the ladle lining can generally reach more than 50 furnaces.

[0072] Comparative Example 1

[0073] In this comparative example, no top slag modifier is added during steel tapping to compare the composition changes of the steel sample and the slag.

[0074] The specific steel-making process is as follows:

[0075] The converter tapped 96.8 tons of molten steel. When tapping, 400 kg of lime was added to the ladle. After 1 / 2 of the steel was tapped, 120 kg of aluminum ingots and 75 kg of medium carbon ferromanganese were added. When the ladle was argon-blown, 28.82 kg of aluminum wire was fed. When the ladle was out of the argon station, steel samples were taken from the ladle.

[0076] Table 4 Composition of converter slag and post-argon ladle slag in comparative example 1

[0077]

[0078] By comparing Comparative Example 1 with the embodiment, it can be seen that if the top slag modifier is not added, the MgO content in the outlet slag is low and the oxidizing property of the slag is strong; the TFe content and FeO content in the outlet slag are high and the alloy yield is low.

[0079] After testing, the total oxygen in the steel sample was 11.5×10 -6 , inclusion density 13.2 pieces / mm 2 , which are much higher than those of the example steel samples. Too many inclusions in aluminum killed steel seriously affect the quality of the steel, and the fracture is obvious during rolling.

[0080] The ladle lining can be used for 42 furnaces, which is significantly lower than the life of the ladle lining after the top slag modifier of the present invention is adopted, which proves that the top slag modifier of the present invention can effectively reduce the erosion of the slag on the lining.

[0081] Comparative Example 2

[0082] The present invention adopts a top slag modifier purchased from another factory, the composition of which is: Al: 49.1%, Al2O3: 10.2%, SiO2: 3.5%; CaO: 21.8%, CaF2: 6.1%, and water content 2.2%; the modifier particle size is 40mm.

[0083] The specific steel-making process is as follows:

[0084] 97.0 tons of molten steel was tapped from the converter. 400 kg of lime and 100 kg of ladle top slag modifier were added to the ladle during tapping. 80 kg of aluminum ingots and 70 kg of medium carbon ferromanganese were added after 1 / 2 of the steel was tapped. 28.73 kg of aluminum wire was fed to the ladle with argon. Samples of converter slag, ladle slag after argon, and steel from the argon outlet station were taken for testing.

[0085] Table 5 Composition of converter slag and post-argon ladle slag in comparative example 2

[0086]

[0087] From the data in Table 5, it can be seen that in Comparative Example 2, a top slag modifier without magnesite and colemanite was added, and the MgO content in the outgoing slag was low, and the slag had a strong ability to corrode magnesia refractory materials. -6 , inclusion density 9.9 pieces / mm 2 Under the same production conditions, the ladle lining can be used for 40 furnaces, which is quite different from the lining life of Comparative Example 1. Compared with Examples 1 to 3, the lining life is reduced by 10 furnaces, indicating that the top slag modifier used in Comparative Example 2 does not have the function of protecting the ladle lining.

[0088] In Comparative Example 2, CaF2 is used in the top slag modifier to adjust the fluidity of the slag, which causes great pollution to the environment.

[0089] Comparative Example 3

[0090] This comparative example is a comparative example of Example 1. The contents of colemanite and magnesiaite in the top slag modifier are respectively within the range specified in the present invention, but the total amount of the two is greater than 10%.

[0091] The raw material composition of the top slag modifier is (by weight): 55% aluminum particles, 8% carbon powder, 20% active lime, 10% colemanite, 4% boraxite, and 3% bentonite.

[0092] The preparation method of the top slag modifier and the smelting and steelmaking method are the same as those in Example 1.

[0093] Table 6 Composition of converter slag and post-argon ladle slag in comparative example 3

[0094]

[0095] The steel sample was taken out from the argon station for testing and found that the total oxygen in the steel was 8.8×10 -6 , inclusion density 9.7 pieces / mm 2 Under the same production conditions, the ladle lining can be used for 44 furnaces.

[0096] Compared with Example 1, the MgO content in the ladle slag after argon in this comparative example is low, resulting in strong corrosion of the slag to the ladle lining, and the boron oxide content in the steel is relatively high, which further increases the erosion of the slag on the ladle lining, resulting in the life of the ladle lining being reduced by about 7 furnaces; although a certain amount of boron magnesium stone component is also added to the modifier, the slag still has a certain damaging effect on the life of the ladle lining.

[0097] Since the total amount of colemanite and magnesiaite exceeds 10%, the fluidity of the slag system is slightly stronger, and the erosion of the ladle lining by boron oxide is increased.

[0098] Comparative Example 4

[0099] This comparative example is a comparative example of Example 1, in which the content of boraxite in the top slag modifier is increased to 10%, and the content of colemanite and boraxite is greater than 10%.

[0100] The raw material composition of the top slag modifier is (by weight percentage): 54% aluminum particles, 8% carbon powder, 20% active lime, 5% colemanite, 10% boraxite, and 3% bentonite.

[0101] The preparation method of the top slag modifier and the smelting and steelmaking method are the same as those in Example 1.

[0102] Table 7 Composition of converter slag and post-argon ladle slag in Comparative Example 4

[0103]

[0104] The steel sample was taken out from the argon station for testing and found that the total oxygen in the steel was 9.3×10 -6 , inclusion density 11.5 pieces / mm 2 Compared with the top slag modifier of the present invention, the total oxygen in the steel increases by about 0.5×10 -6 , the inclusion density increases by about 1.5 / mm 2 This is because the content of magnesia borate is too high, which leads to a significant increase in the MgO content in the slag, a significant increase in the slag viscosity, and a deterioration in fluidity, which reduces the slag's adsorption effect on inclusions in molten steel, thereby increasing the content of inclusions in molten steel and increasing the density of inclusions.

[0105] Compared with Example 1, the life of the ladle lining of this comparative example is 55 furnaces, which is increased by 4 furnaces; this is also because the high Mg content in the slag effectively reduces the erosion of the slag on the lining.

[0106] Comparative Example 5

[0107] This comparative example is a comparative example of Example 1, and the content of the aluminum component is less than 50%.

[0108] The raw material composition of the top slag modifier is (by weight): 48% aluminum particles, 17% carbon powder, 22% active lime, 5% colemanite, 5% boraxite, and 3% bentonite.

[0109] The preparation method of the top slag modifier is the same as that in Example 1.

[0110] After using the top slag modifier of this comparative example, the aluminum content as the main deoxidizing component is lower than the specified range, resulting in insufficient deoxidation of the molten steel. The carbon content in the molten steel increases from 0.05% before refining to 0.07% after refining, exceeding the internal standard of the enterprise by 0.06%, and cannot be shipped as qualified steel. Although carbon powder also has reducing properties, its reducing property is lower than that of aluminum particles, and the reaction speed is slow. Even if the amount of carbon powder is increased, it cannot replace aluminum particles.

[0111] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A modifier for aluminum killed steel ladle top slag, characterized in that It contains the following components in weight percentage: 50% to 60% aluminum particles, 5% to 10% carbon powder, 15% to 25% active lime, 3% to 7% colemanite, 3% to 7% boraxite, and 2% to 3% binder, wherein the total proportion of colemanite and boraxite does not exceed 10%.

2. The aluminum killed steel ladle top slag modifier according to claim 1, characterized in that It contains the following components in weight percentage: 52% to 58% aluminum particles, 5% to 8% carbon powder, 20% to 25% active lime, 3% to 5% colemanite, 4% to 7% boraxite, and 2% to 3% binder, wherein the total proportion of colemanite and boraxite does not exceed 10%.

3. The aluminum killed steel ladle top slag modifier according to any one of claims 1 or 2, characterized in that: The aluminum content in the aluminum particles is greater than 98%; the binder is bentonite; the activity of the active lime is greater than 330ml / 4N-HCI, and the CaO content is greater than 85%.

4. The method for preparing the aluminum killed steel ladle top slag modifier according to any one of claims 1 to 3, characterized in that The following steps are involved: S1, crushing and drying boraxite, colemanite and active lime respectively, and then uniformly mixing the dried boraxite, colemanite, active lime, aluminum particles, carbon powder and binder; S2, using a ball press to granulate the mixed raw materials; S3. Bake the pressed balls and pack them in sealed packages.

5. The method for preparing the aluminum killed steel ladle top slag modifier according to claim 4, characterized in that: In the step S1, borax, colemanite, active lime, aluminum particles and carbon powder are firstly mixed evenly, and then a binder is added to the mixture and mixed evenly.

6. The method for preparing the aluminum killed steel ladle top slag modifier according to claim 5, characterized in that: The crushed particle size of the boraxite and colemanite is 0.3-2.0 mm, the crushed particle size of the active lime is 0.3-1 mm, the particle size of the aluminum particles is less than 5 mm, and the particle size of the carbon powder is less than 1 mm.

7. The method for preparing the aluminum killed steel ladle top slag modifier according to claim 4, characterized in that: In the step S2, the mixed raw material is pressed into material balls with a particle size of 20-40 mm by a ball press.

8. The method for preparing the aluminum killed steel ladle top slag modifier according to claim 4, characterized in that: In step S3, the baking temperature is controlled at 50-100° C., and the baking time is 6-10 hours.

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