Barium calcium aluminate desulfurizer, method for preparing the same, and method for preparing steel

Abstract

The present application relates to a kind of barium calcium aluminate desulfurizer and its preparation method and steel preparation method.The barium calcium aluminate desulfurizer includes 3CaO·Al2O3 phase,12CaO·7Al2O3 phase,2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase;In the barium calcium aluminate desulfurizer, the total mass of 3CaO·Al2O3 phase,12CaO·7Al2O3 phase,2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase accounts for ≥50%.The barium calcium aluminate desulfurizer can significantly reduce the melting point of barium calcium aluminate desulfurizer, speed up the melting speed of desulfurizer, so that it can be completely liquefied as soon as possible and fully react with molten steel, thereby improving the desulfurization efficiency, shorten the desulfurization time, and obtain higher desulfurization rate under the condition of same use amount.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steelmaking, in particular to a barium calcium aluminate desulfurizer, a preparation method thereof and a steel production method. BACKGROUND

[0002] Sulfur is a harmful impurity in steel and iron, and the sulfur content has a great influence on the ferromagnetic properties of silicon steel products. The development of low-sulfur silicon steel is an important direction to improve the magnetic permeability and reduce the iron loss of silicon steel products. The modern steel production process mainly consists of converter-RH furnace-continuous casting and other processes. The desulfurization treatment of molten steel is usually carried out in the middle and late stages of RH furnace refining. However, the traditional RH furnace desulfurizer has the problems of large usage amount, long desulfurization time and low desulfurization rate, which seriously restricts the quality and production capacity of silicon steel products. SUMMARY

[0003] Therefore, it is necessary to provide a barium calcium aluminate desulfurizer, a preparation method thereof and a steel production method to overcome the problems of large usage amount, long desulfurization time and low desulfurization rate of the traditional RH furnace desulfurizer.

[0004] The above-mentioned object of the present application is achieved by the following technical solutions:

[0005] In a first aspect, the present application provides a barium calcium aluminate desulfurizer, which comprises 3CaO·Al2O3 phase, 12CaO·7Al2O3 phase, 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase.

[0006] In the barium calcium aluminate desulfurizer, the total mass percentage of the 3CaO·Al2O3 phase, the 12CaO·7Al2O3 phase, the 2BaO·6CaO·4SiO2 phase and the BaO·Al2O3 phase is ≥50%.

[0007] In one embodiment, in the barium calcium aluminate desulfurizer, the total mass percentage of the 2BaO·6CaO·4SiO2 phase and the BaO·Al2O3 phase is ≥15%.

[0008] In one embodiment, the melting point of the barium calcium aluminate desulfurizer is 1230℃-1300℃.

[0009] In one embodiment, the barium calcium aluminate desulfurizer satisfies one or more of the following conditions:

[0010] 1) the particle size is 3mm-50mm or ≤1mm;

[0011] 2) the logarithmic sulfur capacity at 1450℃-1550℃ is -2.4--2.1;

[0012] 3) comprising components with the following mass proportions: CaO, 40%~50%; BaO, 8%~20%; Al2O3, 30%~45%; SiO2, 1%~8%.

[0013] In a second aspect, the application provides a method for preparing the barium calcium aluminate desulfurizer as described above, comprising the following steps:

[0014] providing a mixture containing a calcium source, a barium source, an aluminum source and a silicon source;

[0015] completely melting the mixture to obtain a liquid mixture;

[0016] cooling and solidifying the liquid mixture by a gradient cooling method to obtain the barium calcium aluminate desulfurizer.

[0017] In one embodiment, the step of completely melting the mixture comprises the following steps:

[0018] heating to 1500°C~1550°C and maintaining for at least 15 min.

[0019] In one embodiment, the step of completely melting the mixture further comprises a step of gas flow stirring.

[0020] In one embodiment, the gas for the gas flow stirring is nitrogen and / or argon.

[0021] In one embodiment, the gradient cooling method comprises the following steps:

[0022] maintaining the liquid mixture at a temperature ≥800°C for ≥24h;

[0023] cooling from 800°C to 500°C at a rate ≥150°C / h;

[0024] cooling from 500°C to 300°C at a rate ≥80°C / h;

[0025] cooling from 500°C to room temperature at a rate ≥40°C / h.

[0026] In one embodiment, one or more of the following conditions are met:

[0027] 1) the calcium source is quicklime powder and / or limestone powder;

[0028] 2) the barium source is one or more of barium oxide powder, barium hydroxide powder and barium carbonate powder;

[0029] 3) the aluminum source is aluminum oxide powder;

[0030] 4) the particle size of the calcium source, the barium source and the aluminum source is independently 50 mesh~200 mesh.

[0031] In a third aspect, the present application provides a method for preparing steel, which comprises the step of desulphurizing molten steel with the calcium barium aluminate desulphurizer as described above.

[0032] In one embodiment, the calcium barium aluminate desulphurizer is added in an amount of 3-15 kg per ton of molten steel.

[0033] The present application has the following advantages:

[0034] In the calcium barium aluminate desulphurizer provided by the present application, the melting points of the 2BaO·6CaO·4SiO2 phase and the BaO·Al2O3 phase are in the range of 1260-1290℃, which is lower than all the phases of the CaO-Al2O3 system; the 3CaO·Al2O3 phase and the 12CaO·7Al2O3 phase can enhance the activity of CaO and promote desulphurization. Controlling the total mass proportion of the 3CaO·Al2O3 phase, the 12CaO·7Al2O3 phase, the 2BaO·6CaO·4SiO2 phase and the BaO·Al2O3 phase to be more than 50% can fully exert the synergistic enhancement effect among the four phases, significantly reduce the melting point of the calcium barium aluminate desulphurizer, accelerate the melting speed of the desulphurizer, and make it fully liquefy as soon as possible to fully react with the molten steel, thereby improving the desulphurization rate and shortening the desulphurization time. Compared with the desulphurizer of the CaO-Al2O3 system, the CaO-BaO-Al2O3 system has a higher sulphur capacity, which can further enhance the desulphurization capacity of the calcium barium aluminate desulphurizer, so that the desulphurizer can obtain a higher desulphurization rate under the same usage amount. DETAILED DESCRIPTION

[0035] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0036] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implying the number of the technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0038] Terms and definitions:

[0039] In the present application, the particle size refers to the size of the particle, also known as the particle size. Specifically, the particle size of a spherical particle is the diameter of the measured particle, and the particle size of a non-spherical particle is usually represented by an equivalent particle size, that is, the particle size of a homogeneous spherical particle with the same volume or the same projected area as the measured particle is used as the particle size of the measured particle.

[0040] In the present application, the sulfur capacity (Sulfur Capacity, Cs) is an important indicator for measuring the desulfurization capacity of the desulfurizer in the metallurgical process, which can be calculated by thermodynamic software such as FactSage, or measured by experimental method. The logarithmic sulfur capacity (lgCs) is the sulfur capacity converted to the logarithm of 10, and the larger the logarithmic sulfur capacity, the stronger the desulfurization capacity of the desulfurizer.

[0041] In the present application, the gas flow stirring refers to a method of blowing gas flow into a liquid or a solid-liquid mixture for stirring.

[0042] In the present application, room temperature refers to indoor temperature, general temperature or normal temperature, which is usually in the range of 15℃-30℃.

[0043] Vacuum refining of molten steel by RH furnace is a key technology to obtain high-quality steel, which can effectively remove carbon, oxygen, sulfur, phosphorus and other impurity elements in the molten steel. Among them, the desulfurization treatment is carried out in the middle and late stages of RH furnace refining, and the commonly used desulfurizers mainly include CaO-CaF2 slag system and CaO-Al2O3 slag system.

[0044] CaO-CaF2 slag system is currently recognized as the desulfurizer with the highest sulfur capacity, but in the actual desulfurization process, the desulfurization effect of CaO-CaF2 slag system is not ideal and unstable, and fluorides can also seriously erode steelmaking equipment and cause environmental pollution. The CaO-Al2O3 slag system has a high melting point, and the relative slagging speed is slowed down, resulting in unsatisfactory desulfurization effect, which seriously affects the production capacity and quality of silicon steel and other steel products.

[0045] This is because the desulfurizer for RH furnace stays in the vacuum chamber for a short time during desulfurization treatment, and cannot play a desulfurization role after leaving the vacuum chamber. In the vacuum chamber, the CaO-Al2O3 slag system has a high melting point and has not completely melted when contacting the molten steel, so there is no sufficient reaction between the desulfurizer and the molten steel, and the desulfurization rate is very low when the amount of desulfurizer added is small. If the desulfurization rate is to be improved, the amount of desulfurizer used usually needs to be increased and the desulfurization time needs to be extended, which will greatly increase the cost of desulfurization treatment. The inventors have further found that the composition and content of each phase in the desulfurizer affect the melting point of the desulfurizer, which in turn greatly affects the amount of desulfurizer used, the desulfurization time, the sulfur capacity and the desulfurization rate and other properties.

[0046] Based on this, the first aspect of the present application provides a barium calcium aluminate desulfurizer to overcome the problems of large amount of use, long desulfurization time and low desulfurization rate of conventional desulfurizers.

[0047] In some embodiments, the barium calcium aluminate desulfurizer includes 3CaO·Al2O3 phase, 12CaO·7Al2O3 phase, 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase.

[0048] In the barium calcium aluminate desulfurizer, the total mass percentage of 3CaO·Al2O3 phase, 12CaO·7Al2O3 phase, 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase is ≥50%.

[0049] The melting point of 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase in the barium calcium aluminate desulfurizer provided by the present application is in the range of 1260℃ to 1290℃, which is lower than that of all phases of CaO-Al2O3 system; 3CaO·Al2O3 phase and 12CaO·7Al2O3 phase can enhance the activity of CaO and promote desulfurization. Controlling the total mass percentage of 3CaO·Al2O3 phase, 12CaO·7Al2O3 phase, 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase to be more than 50% can fully exert the synergistic effect between the four phases, significantly reduce the melting point of the barium calcium aluminate desulfurizer, speed up the melting speed of the desulfurizer, and make it completely liquefy as soon as possible to fully react with the molten steel, thereby improving the desulfurization rate and shortening the desulfurization time. Compared with the desulfurizer of CaO-Al2O3 system, the CaO-BaO-Al2O3 system has a higher sulfur capacity, which can further enhance the desulfurization capacity of the barium calcium aluminate desulfurizer, so that the desulfurizer can obtain a higher desulfurization rate under the same amount of use.

[0050] Optionally, in the barium calcium aluminate desulfurizer, the total mass percentage of 3CaO·Al2O3 phase, 12CaO·7Al2O3 phase, 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase is 50% to 95%, and in some specific examples, the total mass percentage of 3CaO·Al2O3 phase, 12CaO·7Al2O3 phase, 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase in the barium calcium aluminate desulfurizer can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%, etc.

[0051] In some embodiments, in the barium calcium aluminate desulfurizer, the total mass percentage of 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase is ≥15%.

[0052] Optionally, in the barium calcium aluminate desulfurizer, the total mass percentage of 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase is 15% to 35%, and in some specific examples, the total mass percentage of 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase in the barium calcium aluminate desulfurizer can be 15%, 20%, 25%, 30% or 35%, etc.

[0053] The melting point of 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase is between 1260°C and 1290°C, and the sulfur capacity of BaO is higher, so increasing the total mass percentage of these two phases as much as possible can further improve the desulfurization capacity of the barium calcium aluminate desulfurizer.

[0054] In some embodiments, the barium calcium aluminate desulfurizer includes the following mass percentage of components: CaO, 40% to 50%; BaO, 8% to 20%; Al2O3, 30% to 45%; SiO2, 1% to 8%; and the balance is impurities.

[0055] Controlling the mass percentage of CaO, BaO, Al2O3 and SiO2 components in the barium calcium aluminate desulfurizer within a suitable range is conducive to forming 3CaO·Al2O3 phase, 12CaO·7Al2O3 phase, 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase in the desulfurizer, and controlling the total content of the above phases within a specific range.

[0056] Further optionally, in the barium calcium aluminate desulfurizer, the mass percentage of the components of impurities should meet the following conditions: MgO ≤ 8%; TiO2 ≤ 0.1%; C ≤ 0.15%; S ≤ 0.1%.

[0057] Controlling the upper limit of the impurity component in the barium calcium aluminate desulfurizer can avoid the impurity component from entering the molten steel during the desulfurization process and affecting the cleanliness of the molten steel, thereby improving the product quality.

[0058] In some embodiments, the melting point of the barium calcium aluminate desulfurizer is 1230℃-1300℃. In some specific examples, the melting point of the barium calcium aluminate desulfurizer can be 1230℃, 1235℃, 1240℃, 1245℃, 1250℃, 1255℃, 1260℃, 1265℃, 1270℃, 1275℃, 1280℃, 1285℃, 1290℃, 1295℃, or 1300℃, etc.

[0059] The temperature of the molten steel smelting is usually around 1550℃-1600℃, and the temperature of the interface between the desulfurizer and the molten steel is usually around 1500℃. The melting point of the barium calcium aluminate desulfurizer is 1230℃-1300℃, which can make it quickly melt to form a liquid phase, and the liquid desulfurizer and the molten steel can have a sufficient liquid-phase desulfurization reaction, the desulfurization speed is fast, the desulfurizer utilization rate is high, and the desulfurization rate is greatly improved.

[0060] In some embodiments, the logarithmic sulfur capacity of the barium calcium aluminate desulfurizer at 1450℃-1550℃ is -2.4 to -2.1. In some specific examples, the logarithmic sulfur capacity of the barium calcium aluminate desulfurizer at 1450℃-1550℃ can be -2.40, -2.35, -2.30, -2.25, -2.20, -2.15, or -2.10, etc.

[0061] Alternatively, the particle size of the barium calcium aluminate desulfurizer is 3mm-50mm, and in some specific examples, the particle size of the barium calcium aluminate desulfurizer can be 3mm, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, or 50mm, etc.

[0062] Alternatively, the particle size of the barium calcium aluminate desulfurizer is ≤1mm, and in some specific examples, the particle size of the barium calcium aluminate desulfurizer can be 0.01mm, 0.02mm, 0.05mm, 0.08mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or 1mm, etc.

[0063] Controlling the particle size of the barium calcium aluminate desulfurizer in the range of 3mm-50mm can increase the specific surface area of the desulfurizer, which is beneficial to the rapid dispersion and reaction in the molten steel, and accelerates the desulfurization rate. On the other hand, it can prevent the desulfurizer from being easily scattered and lost due to too small particle size, and avoid the problem of too high processing cost of small particle size. Controlling the particle size of the barium calcium aluminate desulfurizer to be ≤1mm is suitable for using the spray method to desulfurize the molten steel, which can make the desulfurizer disperse uniformly in a very short time, and further improve the desulfurization effect.

[0064] In the second aspect of the present application, a preparation method of the barium calcium aluminate desulfurizer is provided, which is used to prepare the barium calcium aluminate desulfurizer described above.

[0065] In some embodiments, the preparation method of the barium calcium aluminate desulfurizer comprises the following steps:

[0066] Providing a mixture containing a calcium source, a barium source, an aluminum source and a silicon source;

[0067] Fully melting the mixture to obtain a liquid mixture;

[0068] Cooling and solidifying the liquid mixture by the gradient cooling method to obtain the barium calcium aluminate desulfurizer.

[0069] The present application melts the mixture to promote the interaction of the calcium source, the barium source, the aluminum source and the silicon source in the mixture, and forms low-melting-point 3CaO·Al2O3 phase, 12CaO·7Al2O3 phase, 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase in the gradient cooling process, which reduces the melting point of the barium calcium aluminate desulfurizer and improves the melting speed during use, so that a higher desulfurization rate can be obtained under the condition of the same amount of desulfurizer.

[0070] In some embodiments, providing the mixture containing the calcium source, the barium source, the aluminum source and the silicon source comprises the following steps: grinding the calcium source, the barium source, the aluminum source and the silicon source respectively, mixing to obtain the mixture.

[0071] The content of silicon oxide in the barium calcium aluminate desulfurizer is only 1%-8%, and usually no silicon oxide powder or other raw materials as a silicon source need to be added separately, but exists in the form of impurities in the calcium source, the barium source and the aluminum source, that is, one or more of the calcium source, the barium source and the aluminum source can be used as a silicon source at the same time. If the purity of the calcium source, the barium source and the aluminum source is very high, and the content of silicon oxide is insufficient, a small amount of silicon oxide powder can be additionally added as a silicon source.

[0072] Optionally, the calcium source is lime powder and / or limestone powder.

[0073] The quicklime (CaO) powder meets the quality requirements of the general metallurgical lime of the second level in YB / T 042-2014 Metallurgical Lime, i.e., the mass fraction of each component is: CaO≥85%, MgO<5%, SiO2≤3.5%, and S≤0.05%. The limestone (CaCO3) powder meets the quality requirements of the general limestone PS530 in YB / T 5279-2005 Limestone, i.e., the mass fraction of each component is: CaO≥53%, MgO≤3.0%, SiO2≤1.5%, and S≤0.035%.

[0074] Optionally, the barium source is one or more of barium oxide powder, barium hydroxide powder, and barium carbonate powder.

[0075] In the barium oxide (BaO) powder, the mass fraction of BaO is≥90%, and the mass fraction of SiO2 can be 1% to 10%. The barium hydroxide (Ba(OH)2) powder meets the quality requirements of the superior product in HG / T 2566-2006 Industrial Barium Hydroxide, i.e., the mass fraction of Ba(OH)2 is≥98.0%. The barium carbonate (BaCO3) powder meets the quality requirements of the superior product in GB / T 1614-2021 Industrial Barium Carbonate, i.e., the mass fraction of BaCO3 is≥99.2%.

[0076] Optionally, the aluminum source is aluminum oxide powder.

[0077] The aluminum oxide (Al2O3) powder meets the quality requirements of at least one of the YAO-1, YAO-2, and YAO-3 grades in YS / T 803-2012 Metallurgical Grade Aluminum Oxide, i.e., the mass fraction of each component is: Al2O3≥98.4%, and SiO2≤0.06%.

[0078] Optionally, the method of the grinding treatment is one or more of the ball milling method, the mechanical grinding method, and the ultrasonic grinding method.

[0079] Optionally, the particle size of the calcium source, the barium source, the aluminum source, and the silicon source is independently 50 mesh to 200 mesh (i.e., 74 μm to 280 μm). In some specific examples, the particle size of the calcium source, the barium source, the aluminum source, and the silicon source can be independently 50 mesh, 60 mesh, 70 mesh, 80 mesh, 90 mesh, 100 mesh, 110 mesh, 120 mesh, 130 mesh, 140 mesh, 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh, or 200 mesh, etc.

[0080] By controlling the particle size of the calcium source, the barium source, the aluminum source, and the silicon source, the raw materials have a large specific surface area, which is conducive to the rapid melting, diffusion, decomposition, and interaction of the raw materials, and promotes the formation of low-melting-point phases.

[0081] In some embodiments, the complete melting of the mixture includes the following steps:

[0082] heating to 1500-1550℃ and holding for at least 15 min.

[0083] In some specific examples, the target temperature of the heating can be 1500℃, 1505℃, 1510℃, 1515℃, 1520℃, 1525℃, 1530℃, 1535℃, 1540℃, 1545℃ or 1550℃, etc.; and the holding time can be 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min or 120 min, etc.

[0084] Heating to 1500-1550℃ can make the mixture completely melt to form a liquid mixture. Holding at 1500-1550℃ for at least 15 min can make the phases in the liquid mixture disperse uniformly, ensuring that the melting point of the barium calcium aluminate desulfurizer is relatively stable.

[0085] Optionally, making the mixture completely melt further includes a step of air flow stirring.

[0086] The device for air flow stirring is simple, has no stirring components, is suitable for stirring of high-temperature liquid or corrosive liquid, and can further improve the uniformity of the dispersion of the liquid mixture. At the same time, air flow stirring can also carry away volatile components in the raw materials, such as CO2 generated by the decomposition of carbonates, to promote the decomposition and interaction of the raw materials.

[0087] Further optionally, the gas for air flow stirring is nitrogen and / or argon.

[0088] Nitrogen and argon are inert gases, which can protect the mixture from the influence of O2, CO2 and other reactive gases during the melting process, avoid the oxidation of impurity elements in the mixture, and prevent the reaction of CaO, BaO and other alkaline oxides with CO2 to form carbonate products, thereby ensuring that the desulfurizer has the advantages of low melting point and high sulfur capacity.

[0089] In some embodiments, the gradient cooling method includes the following steps:

[0090] holding the liquid mixture at a temperature ≥800℃ for ≥24 h;

[0091] cooling from 800℃ to 500℃ at a cooling rate ≥150℃ / h;

[0092] cooling from 500℃ to 300℃ at a cooling rate ≥80℃ / h;

[0093] cooling from 500℃ to room temperature at a cooling rate ≥40℃ / h.

[0094] By the above-mentioned gradient cooling method, the liquid mixture can be caused to perform phase transformation under slow temperature change, so as to avoid too fast temperature change and to avoid formation of insufficient 3CaO·Al2O3 phase, 12CaO·7Al2O3 phase, 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase.

[0095] Optionally, the heat preservation of the liquid mixture at a temperature of ≥800℃ for ≥24h comprises the following steps:

[0096] The liquid mixture is placed in a ferrous container and heat preservation is performed by taking the method of covering and heat preservation.

[0097] Optionally, after the heat preservation at a temperature of ≥800℃ for ≥24h, the method of air cooling is taken to perform gradient cooling to room temperature, so as to obtain the blocky barium calcium aluminate desulfurizer.

[0098] Optionally, the liquid mixture after cooling and solidification further comprises the step of crushing.

[0099] Further optionally, the blocky barium calcium aluminate desulfurizer obtained by the gradient cooling is sequentially subjected to artificial crushing and mechanical crushing, so as to obtain the barium calcium aluminate desulfurizer with a particle size of 3mm-50mm.

[0100] Optionally, the blocky barium calcium aluminate desulfurizer after crushing further comprises the step of grinding.

[0101] Further optionally, the barium calcium aluminate desulfurizer with a particle size of 3mm-50mm is subjected to ball milling, mechanical grinding or ultrasonic grinding, so as to obtain the barium calcium aluminate desulfurizer with a particle size of ≤1mm.

[0102] In a third aspect, the present application provides a preparation method of steel material, which comprises the step of performing desulfurization treatment on molten steel by using the above-mentioned barium calcium aluminate desulfurizer.

[0103] Optionally, the adding amount of the barium calcium aluminate desulfurizer is 3kg-15kg per ton of molten steel.

[0104] The present application will be further described in detail in combination with specific examples. In the following examples, the raw materials used are all commercially available products, unless otherwise specified.

[0105] Example 1

[0106] The quicklime powder (containing silicon oxide impurities), barium carbonate powder and aluminum oxide powder are respectively ball milled to a particle size of 50 mesh to 200 mesh, then the quicklime powder, barium carbonate powder and aluminum oxide powder are added into a mixing bin and uniformly mixed to obtain a mixture; the mixture is placed in an electric furnace, heated to 1500°C to completely melt the mixture, and kept for 30 min, and nitrogen is introduced for airflow stirring during the heating process and the keeping process to obtain a liquid mixture; the liquid mixture is poured into an iron container, and air blowing is used to cool the liquid mixture to room temperature to obtain a blocky barium calcium aluminate desulfurizer; the blocky barium calcium aluminate desulfurizer is manually crushed, and then put into a jaw crusher for mechanical crushing to obtain a barium calcium aluminate desulfurizer with a particle size of 3 mm to 50 mm.

[0107] Referring to Table 1, the barium calcium aluminate desulfurizer includes components with the following mass proportions: CaO, 42%; BaO, 19%; Al2O3, 35%; SiO2, 2%; MgO, 1.8%; TiO2, 0.03%; C, 0.08%; S, 0.04%. Referring to Table 2, the barium calcium aluminate desulfurizer includes phases with the following mass proportions: 3CaO·Al2O3 phase, 37.1%; 12CaO·7Al2O3 phase, 3.4%; 2BaO·6CaO·4SiO2 phase, 7.1%; BaO·Al2O3 phase, 25.2%. In Table 2, C3A represents the 3CaO·Al2O3 phase, C 12 A7 represents the 12CaO·7Al2O3 phase, B2C6S4 represents the 2BaO·6CaO·4SiO2 phase, and BA represents the BaO·Al2O3 phase.

[0108] Example 2

[0109] The quicklime powder (containing silicon oxide impurities), barium carbonate powder and aluminum oxide powder are respectively ball milled to a particle size of 50 mesh to 200 mesh, then the quicklime powder, barium carbonate powder and aluminum oxide powder are added into a mixing bin and uniformly mixed to obtain a mixture; the mixture is placed in an electric furnace, heated to 1500°C to completely melt the mixture, and kept for 30 min, and nitrogen is introduced for airflow stirring during the heating process and the keeping process to obtain a liquid mixture; the liquid mixture is poured into an iron container, and air blowing is used to cool the liquid mixture to room temperature to obtain a blocky barium calcium aluminate desulfurizer; the blocky barium calcium aluminate desulfurizer is manually crushed, and then put into a jaw crusher for mechanical crushing to obtain a barium calcium aluminate desulfurizer with a particle size of 3 mm to 50 mm.

[0110] The barium calcium aluminate desulfurizer includes the following components with the mass ratio: CaO, 45%; BaO, 15%; Al2O3, 36%; SiO2, 2%; MgO, 1.6%; TiO2, 0.04%; C, 0.11%; S, 0.06%. Referring to Table 2, the barium calcium aluminate desulfurizer includes the following phases with the mass ratio: 3CaO·Al2O3 phase, 40.7%; 12CaO·7Al2O3 phase, 7.4%; 2BaO·6CaO·4SiO2 phase, 6.3%; BaO·Al2O3 phase, 19.1%.

[0111] Example 3

[0112] The quicklime powder (containing silicon oxide impurities), barium carbonate powder and aluminum oxide powder are respectively ball milled to the particle size of 50 mesh to 200 mesh, and then the quicklime powder, barium carbonate powder and aluminum oxide powder are added into a mixing bin to be uniformly mixed to obtain a mixture; the mixture is placed in an electric furnace, and is heated to 1550°C to completely melt the mixture, and is kept for 15 min, and argon gas is introduced to perform airflow stirring during the heating process and the keeping process to obtain a liquid mixture; the liquid mixture is poured into an iron container, and air blowing is performed by using an air blower to cool the liquid mixture to room temperature to obtain a blocky barium calcium aluminate desulfurizer; the blocky barium calcium aluminate desulfurizer is manually crushed, and then is put into a jaw crusher to be mechanically crushed to obtain the barium calcium aluminate desulfurizer with the particle size of 3 mm to 50 mm.

[0113] The barium calcium aluminate desulfurizer includes the following components with the mass ratio: CaO, 49%; BaO, 9%; Al2O3, 38%; SiO2, 2%; MgO, 1.7%; TiO2, 0.06%; C, 0.04%; S, 0.05%. Referring to Table 2, the barium calcium aluminate desulfurizer includes the following phases with the mass ratio: 3CaO·Al2O3 phase, 53.2%; 12CaO·7Al2O3 phase, 13.4%; 2BaO·6CaO·4SiO2 phase, 6.5%; BaO·Al2O3 phase, 11.2%.

[0114] Comparative Example 1

[0115] The desulfurizer of the present comparative example is a calcium aluminate desulfurizer without BaO, and has the particle size of 3 mm to 50 mm.

[0116] The calcium aluminate desulfurizer includes the following components with the mass ratio: CaO, 54%; Al2O3, 42%; SiO2, 2%; MgO, 1.5%; TiO2, 0.04%; C, 0.07%; S, 0.04%. Referring to Table 2, the calcium aluminate desulfurizer includes the following phases with the mass ratio: 3CaO·Al2O3 phase, 32.0%; 12CaO·7Al2O3 phase, 43.0%.

[0117] Comparative Example 2

[0118] The barium calcium aluminate desulfurizer of the present comparative example is prepared at a temperature lower than 1500℃.

[0119] The quicklime powder (containing silicon oxide impurities), barium carbonate powder and aluminum oxide powder are respectively ball milled to a particle size of 50 mesh to 200 mesh, and then the quicklime powder, barium carbonate powder and aluminum oxide powder are added into a mixing bin and uniformly mixed to obtain a mixture; the mixture is placed in an electric furnace and heated to 1250℃ to completely melt the mixture, and the temperature is maintained for 15 min, and argon gas is introduced for airflow stirring during the heating process and the temperature maintaining process to obtain a liquid mixture; the liquid mixture is poured into an iron container, and a blower is used to blow air to cool the liquid mixture to room temperature to obtain a blocky barium calcium aluminate desulfurizer; the blocky barium calcium aluminate desulfurizer is manually crushed and then put into a jaw crusher for mechanical crushing to obtain a barium calcium aluminate desulfurizer with a particle size of 3 mm to 50 mm.

[0120] The barium calcium aluminate desulfurizer includes the following components with the mass ratio: CaO, 49%; BaO, 9%; Al2O3, 38%; SiO2, 2%; MgO, 1.7%; TiO2, 0.06%; C, 0.04%; S, 0.06%. Referring to Table 2, the barium calcium aluminate desulfurizer includes the following phases with the mass ratio: 3CaO·Al2O3 phase, 21.0%; 12CaO·7Al2O3 phase, 10.4%; 2BaO·6CaO·4SiO2 phase, 0%; BaO·Al2O3 phase, 4.2%.

[0121] Comparative Example 3

[0122] The barium calcium aluminate desulfurizer of the present comparative example is not subjected to gradient cooling.

[0123] The quicklime powder (containing silica impurities), barium carbonate powder and alumina powder are respectively ball milled to a particle size of 50 mesh to 200 mesh, and then the quicklime powder, barium carbonate powder and alumina powder are added into a mixing bin and uniformly mixed to obtain a mixture; the mixture is placed in an electric furnace, heated to 1530°C to completely melt the mixture, and kept for 15 min, and argon is introduced for airflow stirring during the heating process and the keeping process to obtain a liquid mixture; the liquid mixture is poured into an iron container, and the liquid mixture is naturally cooled to room temperature for 3 days to obtain a blocky barium calcium aluminate desulfurizer; the blocky barium calcium aluminate desulfurizer is manually crushed, and then is put into a jaw crusher for mechanical crushing to obtain a barium calcium aluminate desulfurizer with a particle size of 3 mm to 50 mm.

[0124] Referring to Table 1, the barium calcium aluminate desulfurizer includes components with the following mass proportions: CaO, 49%; BaO, 9%; Al2O3, 38%; SiO2, 2%; MgO, 1.7%; TiO2, 0.06%; C, 0.04%; and S, 0.06%. Referring to Table 2, the barium calcium aluminate desulfurizer includes phases with the following mass proportions: 3CaO·Al2O3 phase, 15.3%; 12CaO·7Al2O3 phase, 3.4%; 2BaO·6CaO·4SiO2 phase, 1.9%; and BaO·Al2O3 phase, 8.2%.

[0125] Test Example

[0126] The content of oxides in the barium calcium aluminate desulfurizer is tested by using an X-ray fluorescence spectrometer, and the carbon content and the sulfur content in the barium calcium aluminate desulfurizer are tested by referring to GB / T 20123-2006 Steel - Determination of total carbon and sulfur content - High frequency induction furnace combustion followed by infrared absorption method, and the results are shown in Table 1. The components in the barium calcium aluminate desulfurizer are input into a thermodynamic software FactSage to calculate the phases, the melting point and the logarithmic sulfur capacity thereof, the mass proportions of the phases of the barium calcium aluminate desulfurizer are shown in Table 2, and the melting point and the logarithmic sulfur capacity are shown in Table 3.

[0127] As shown in Table 2, the total mass proportions of the 2BaO·6CaO·4SiO2 phase and the BaO·Al2O3 phase of the barium calcium aluminate desulfurizers of Examples 1 to 3 are 17.7% to 32.3%, and the total mass proportions of the four target phases are 73.5% to 84.3%. The calcium aluminate desulfurizer of Comparative Example 1 only contains the 3CaO·Al2O3 phase and the 12CaO·7Al2O3 phase; the calcium aluminate desulfurizers of Comparative Examples 2 and 3 do not form enough 3CaO·Al2O3 phase, 12CaO·7Al2O3 phase, 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase, and the total mass proportions of the four target phases are less than 50%, and the total mass proportions of the phases containing BaO are less than 15%.

[0128] From Table 3, the melting point of the barium calcium aluminate desulfurizer of Example 1 is 1296°C, and the logarithmic sulfur capacity lgCs at 1550°C is -2.18. At 1550°C, 33 heats of molten steel were desulfurized, each heat having 150 tons (t) of molten steel, and the barium calcium aluminate desulfurizer was added at a rate of 4 to 9 kg per ton of molten steel, with an average of 7.1 kg per ton. After desulfurization, the average desulfurization rate was 64.6%, with a variance of 5.8%.

[0129] The melting point of the barium calcium aluminate desulfurizer of Example 2 is 1282°C, and the logarithmic sulfur capacity lgCs at 1550°C is -2.24. At 1550°C, 23 heats of molten steel were desulfurized, each heat having 150 tons (t) of molten steel, and the barium calcium aluminate desulfurizer was added at a rate of 5 to 8 kg per ton of molten steel, with an average of 7.12 kg per ton. After desulfurization, the average desulfurization rate was 62.8%, with a variance of 6.1%.

[0130] The melting point of the barium calcium aluminate desulfurizer of Example 3 is 1263°C, and the logarithmic sulfur capacity lgCs at 1550°C is -2.32. At 1550°C, 18 heats of molten steel were desulfurized, each heat having 150 tons (t) of molten steel, and the barium calcium aluminate desulfurizer was added at a rate of 4 to 8 kg per ton of molten steel, with an average of 7.05 kg per ton. After desulfurization, the average desulfurization rate was 56.3%, with a variance of 6.7%.

[0131] The melting point of the calcium aluminate desulfurizer of Comparative Example 1 is 1358°C, and the logarithmic sulfur capacity lgCs at 1550°C is -2.52. At 1550°C, 88 heats of molten steel were desulfurized, each heat having 150 tons (t) of molten steel, and the calcium aluminate desulfurizer was added at a rate of 4 to 9 kg per ton of molten steel, with an average of 7.15 kg per ton. After desulfurization, the average desulfurization rate was 48.3%, with a variance of 7.7%.

[0132] The melting point of the barium calcium aluminate desulfurizer of Comparative Example 2 is 1343°C, and the logarithmic sulfur capacity lgCs at 1550°C is -2.32. At 1550°C, 14 heats of molten steel were desulfurized, each heat having 150 tons (t) of molten steel, and the barium calcium aluminate desulfurizer was added at a rate of 5 to 9 kg per ton of molten steel, with an average of 7.08 kg per ton. After desulfurization, the average desulfurization rate was 51.4%, with a variance of 9.3%.

[0133] The melting point of the barium calcium aluminate desulfurizer of Comparative Example 3 is 1313°C, and the logarithmic sulfur capacity lgCs at 1550°C is -2.32. At 1550°C, 17 heats of molten steel were desulfurized, each heat having 150 tons (t) of molten steel, and the barium calcium aluminate desulfurizer was added at a rate of 6 to 9 kg per ton of molten steel, with an average of 7.25 kg per ton. After desulfurization, the average desulfurization rate was 50.2%, with a variance of 8.9%.

[0134] By comparison, the melting point of the calcium aluminate desulfurizer in Examples 1-3 is in the range of 1230-1300℃, the melting speed is fast during desulfurization treatment, higher logarithmic sulfur capacity and desulfurization rate can be obtained under the condition of the same amount of desulfurizer, and the problems of large amount of desulfurizer, long desulfurization time and low desulfurization rate are avoided. Among them, the desulfurization capacity of the calcium aluminate desulfurizer in Example 1 is the strongest, and the desulfurization effect is the most stable.

[0135] Table 1. Mass percentage (wt.%) of components of desulfurizer

[0136] CaO BaO Al2O3 SiO2 MgO TiO2 C S Example 1 42 19 35 2 1.8 0.03 0.08 0.04 Example 2 45 15 36 2 1.6 0.04 0.11 0.06 Example 3 49 9 38 2 1.7 0.06 0.04 0.05 Comparative Example 1 54 / 42 2 1.5 0.04 0.07 0.04 Comparative Example 2 49 9 38 2 1.7 0.06 0.08 0.06 Comparative Example 3 49 9 38 2 1.7 0.05 0.05 0.04

[0137] Table 2. Mass percentage (wt.%) of phases of desulfurizer

[0138] [C3A] C 12 A7]]> [B2C6S4] BA BaO-containing phases Four target phases Example 1 37.1 3.4 7.1 25.2 32.3 72.8 Example 2 40.7 7.4 6.3 19.1 25.4 73.5 Example 3 53.2 13.4 6.5 11.2 17.7 84.3 Comparative Example 1 32.0 43.0 / / / 75.0 Comparative Example 2 21.0 10.4 0 4.2 4.2 35.6 Comparative Example 3 15.3 3.4 1.9 8.2 10.1 28.8

[0139] Table 3. Performance comparison of desulfurizer

[0140]

[0141] The technical features of the above-described embodiments can be combined arbitrarily, and in order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present disclosure.

[0142] The above-described embodiments only express several embodiments of the present application, the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of variations and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims, and the description can be used to explain the content of the claims.

Claims

1. A barium calcium aluminate desulfurizer, characterized by, 3CaO·Al2O3 phase, 12CaO·7Al2O3 phase, 2BaO·6CaO·4SiO2 phase and BaO·Al2O3 phase; In the calcium barium aluminate desulfurizer, the total mass percentage of the 3CaO·Al2O3 phase, the 12CaO·7Al2O3 phase, the 2BaO·6CaO·4SiO2 phase and the BaO·Al2O3 phase is ≥50%, and the melting point of the calcium barium aluminate desulfurizer is 1230-1300℃; The preparation method of the calcium barium aluminate desulfurizer comprises the following steps: a mixture containing a calcium source, a barium source, an aluminum source and a silicon source is provided; the mixture is completely melted to obtain a liquid mixture; the liquid mixture is cooled and solidified by a gradient cooling method to obtain the calcium barium aluminate desulfurizer; the gradient cooling method comprises the following steps: the liquid mixture is kept at a temperature ≥800℃ for ≥24h; the temperature is decreased from 800℃ to 500℃ at a rate ≥150℃ / h; the temperature is decreased from 500℃ to 300℃ at a rate ≥80℃ / h; the temperature is decreased from 500℃ to room temperature at a rate ≥40℃ / h.

2. The barium calcium aluminate desulfurizer according to claim 1, wherein In the calcium barium aluminate desulfurizer, the total mass percentage of the 2BaO·6CaO·4SiO2 phase and the BaO·Al2O3 phase is ≥15%.

3. The barium calcium aluminate desulfurizer according to claim 1, wherein In the calcium barium aluminate desulfurizer, the total mass percentage of the 3CaO·Al2O3 phase, the 12CaO·7Al2O3 phase, the 2BaO·6CaO·4SiO2 phase and the BaO·Al2O3 phase is 50-95%.

4. The barium calcium aluminate desulfurizer according to any one of claims 1 to 3, characterized in that, The calcium barium aluminate desulfurizer satisfies one or more of the following conditions: 1) the particle size is 3-50mm or ≤1mm; 2) the logarithmic sulfur capacity at 1450-1550℃ is -2.4--2.1; 3) the components include the following mass percentages: CaO, 40-50%; BaO, 8-20%; Al2O3, 30-45%; SiO2, 1-8%.

5. A process for producing the barium calcium aluminate desulfurizer according to any one of claims 1 to 4, characterized by, comprises the following steps: a mixture containing a calcium source, a barium source, an aluminum source and a silicon source is provided; the mixture is completely melted to obtain a liquid mixture; the liquid mixture is cooled and solidified by a gradient cooling method to obtain the calcium barium aluminate desulfurizer; the gradient cooling method comprises the following steps: the liquid mixture is kept at a temperature ≥800℃ for ≥24h; the temperature is decreased from 800℃ to 500℃ at a rate ≥150℃ / h; the temperature is decreased from 500℃ to 300℃ at a rate ≥80℃ / h; the temperature is decreased from 500℃ to room temperature at a rate ≥40℃ / h.

6. The method of producing barium calcium aluminate desulfurizer according to claim 5, characterized by, comprises the following steps: the temperature is increased to 1500-1550℃ and kept for at least 15min.

7. The method of producing barium calcium aluminate desulfurizer according to claim 6, characterized by, comprises the following steps:

8. The method of producing barium calcium aluminate desulfurizer according to claim 7, characterized by, the temperature is increased to 1500-1550℃ and kept for at least 15min.

9. The method of producing barium calcium aluminate desulfurizer according to claim 5, characterized by, the gas flow stirring is nitrogen and / or argon. satisfies one or more of the following conditions: 1) the calcium source is quicklime powder and / or limestone powder; 2) the barium source is one or more of barium oxide powder, barium hydroxide powder and barium carbonate powder; 3) the aluminum source is aluminum oxide powder; 4) the particle size of each of the calcium source, the barium source and the aluminum source is independently 50 mesh to 200 mesh.

10. A method of producing a steel material, characterized by, including the step of subjecting molten steel to desulfurization treatment using the calcium barium aluminate desulfurizer according to any one of claims 1 to 4.

11. The method of producing a steel material according to claim 10, characterized by, The amount of the calcium barium aluminate desulfurizer added per ton of molten steel is 3 kg to 15 kg.

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