Converter slagging agent as well as preparation method and use method thereof

Abstract

The invention provides a converter slagging agent which comprises the following components in percentage by mass: 40%-60% of converter dedusting ash, 40%-60% of ladle casting residues and 4%-15% of a binder, and the converter slagging agent comprises the following components in percentage by mass: 25%-38% of TFe, 20%-30% of CaO, 15%-35% of Al2O3, 3%-8% of SiO2 and 3%-5% of MgO. The invention also provides a preparation method and a use method of the converter slagging agent. According to the converter slagging agent and the preparation method and the use method thereof, the preparation process is simple, use is convenient, the slagging effect is obvious, resource recycling can be promoted, and the problems that traditional converter slagging pollutes the environment, erodes refractory materials and the like are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of resource recycling, and in particular to a converter slagging agent and a preparation method and a use method thereof. Background Art

[0002] my country's steel industry has developed rapidly, with crude steel output exceeding 1 billion tons for many consecutive years. As steel production increases, solid waste from the production process is also increasing, which not only occupies a large amount of land, but also has a serious impact on the environment, making steel production face major challenges in environmental protection and energy conservation and emission reduction. Therefore, the disposal of steelmaking solid waste needs to be solved urgently.

[0003] At present, the comprehensive utilization rate of casting slag in most steel mills is only about 10%. Usually, cooling-magnetic separation is used to separate some of the metal materials, and the remaining tailings can only be piled up or landfilled. The CaO content in ladle casting slag is usually 30-45%, the Al2O3 content is 25-55%, the TFe content is less than 5%, and the SiO2 content is 5-10%. The ladle casting slag is pre-melted at high temperature by heating molten steel, which is a high-quality pre-melted slag. In addition, the Al2O3 content in the casting slag is relatively high, which can reduce the melting point and is beneficial to slagging. Part of the LF refining slag is hot-cycled in the ladle. The recycling of hot refining slag from LF furnace can reduce the consumption of lime and bauxite and shorten the heating time. Some ladle casting slag is also used as raw material for cement production.

[0004] A large amount of harmful smoke will be generated during the converter steelmaking process. After being processed and recycled by the dust removal equipment, dust ash with fine particle size and high iron content can be obtained. The TFe content in the converter dust ash can reach about 55%. It has fine particle size, large specific surface area, low melting point (melting point is about 1370℃, lower than 1566℃ of iron oxide), strong reactivity, and is a high-quality secondary resource. On-site use shows that the use of converter dust ash briquettes has good cooling and slag-removing effects, can replace iron balls, slag steel and iron ore, and can realize the "full closed-loop" comprehensive utilization of converter dust ash. The invention patent with application number 202011032932.6 is a method for deep dephosphorization with dust ash. In the process of converter steelmaking, converter dust ash is added into the ladle for post-converter dephosphorization, which has a good dephosphorization and slag-removing effect. In addition, some use converter dust ash as raw materials for sintered ore.

[0005] In order to achieve better dephosphorization effect in converter steelmaking process, rapid slagging is required in the early stage of steelmaking to form slag with certain basicity, low melting point and good fluidity. The traditional converter slagging agent is fluorite, which has obvious slagging effect, but it is easy to volatilize and contains fluorine, which will pollute the environment. Moreover, the addition of fluorite will aggravate the erosion of slag on refractory materials, so the use of F-free slagging agent has become a trend.

[0006] At present, the use of solid waste generated in the metallurgical process to prepare converter steelmaking slag-removing agent is a research direction of steelmaking. For example, the patent application with application number 202011037636.5 uses refined slag tailings, iron oxide, lime and binder to prepare converter slag-removing agent; the patent application with application number 201711308607.6 uses steelmaking dust, steelmaking sludge, quartz sand, cement and binder to prepare converter slag-removing agent; the patent application with application number 202311527084.X uses iron-rich red mud, refined slag, converter dust and iron oxide to prepare converter slag-removing agent. It has played a positive role in the comprehensive utilization of converter slag and metallurgical solid waste, but they also have problems such as low slag-removing effect, complex process flow, low resource utilization, easy erosion of refractory materials and still have an impact on the environment.

[0007] Therefore, it is still necessary to develop a method for recycling steelmaking solid waste to prepare an efficient slag-removing agent for converters, which not only simplifies the preparation process, but also makes the slag-removing effect of the slag-removing agent obvious, which can not only promote the recycling of resources, but also solve the problems of environmental pollution and erosion of refractory materials caused by traditional converter slag-removing. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a converter slag-removing agent with a simple preparation process, obvious slag-removing effect, the ability to promote resource recycling, and the ability to solve the problems of environmental pollution and erosion of refractory materials caused by traditional converter slag-removing, as well as a preparation method and a use method thereof.

[0009] In order to solve the above technical problems, the present invention provides a converter slag-forming agent, which comprises, by mass percentage, 40%-60% of converter dust removal ash, 40%-60% of ladle casting slag and 4%-15% of binder, and the converter slag-forming agent components include TFe 25%-38%, CaO 20%-30%, Al2O3 15%-35%, SiO2 3%-8%, and MgO 3%-5%.

[0010] Furthermore, the TFe content of the converter dust is 40%-60%.

[0011] Furthermore, in terms of mass percentage, the ladle casting slag components include CaO 30%-45%, Al2O3 25%-55%, MgO 4%-7%, TFe 0.5%-8%, and SiO2 5%-10%.

[0012] Furthermore, the binder includes bentonite or magnesium chloride.

[0013] The present invention also provides a method for preparing a converter slag-forming agent, comprising the following steps:

[0014] In terms of mass percentage, the raw materials are prepared according to 40%-60% of converter dust, 40%-60% of ladle casting slag and 4%-15% of binder;

[0015] crushing the ladle casting slag to obtain the ladle casting slag powder;

[0016] The ladle casting slag powder, converter dust removal ash and binder are mixed with water to obtain a mixture;

[0017] Pressing the mixture into balls to obtain finished balls;

[0018] The finished balls are dried and dehydrated to obtain the converter slag-removing agent.

[0019] Furthermore, the particle size of the converter dust is less than 1 mm, and the particle size of the ladle casting slag powder is less than 3 mm.

[0020] Furthermore, the diameter of the finished ball is 5-15 cm, and the water content of the finished ball after drying and dehydration is less than 2%.

[0021] The present invention provides a method for using a converter slag-forming agent, which comprises adding prepared converter slag-forming agent balls into a converter silo, and adding the slag-forming agent into the converter for slag-forming according to the converter slag-forming conditions at the initial stage of converter smelting and at various periods during the converter smelting process when slag-forming is required.

[0022] Furthermore, the slag-forming agent is added to the converter for slag forming by a single slag method, the amount of slag-forming agent used in converter smelting is 5-25kg / ton of steel, the furnace temperature in the initial stage of converter smelting is 1300-1450°C, and 60%-70% of the total slag-forming agent is added in the initial stage of converter smelting; the furnace temperature during converter smelting is 1450-1650°C, and the remaining slag-forming agent is added in batches according to the converter slag forming situation at each period of converter smelting that requires slag forming, and the slag forming time after each addition of the slag-forming agent is 0.5-2min.

[0023] Furthermore, the slag-removing agent is added to the converter to remove slag using the double slag method. The amount of slag-removing agent added during the dephosphorization period is determined according to the silicon conditions of the molten iron and the conditions of the steel grade. The agent is added when the basicity CaO / SiO2>1.4, and the comprehensive basicity CaO / (SiO2+Al2O3) is controlled between 1.4-2.0; the agent is added 0.5-2 minutes after the auxiliary materials are added during the decarburization period, and 5-15kg / ton of steel is added to promote converter slag removal under low silicon conditions.

[0024] The present invention provides a converter slag-forming agent, which contains up to 40%-60% of ladle casting slag mainly composed of 12CaO·7Al2O3, and the melting point of 12CaO·7Al2O3 is 1392°C, and it melts rapidly at the converter temperature. The melted Al2O3 combines with the converter slag to form a complex compound, and since Al2O3 can reduce the melting point of the slag, it has the effect of diluting the alkaline slag. In this way, the melting point of the slag-forming agent is relatively low. When the converter slag-forming is difficult, the low-melting-point slag-forming agent can be added to the converter to melt rapidly, and the unmelted slag material dissolves in the liquid slag-forming agent to form low-melting-point converter slag. Therefore, the low-melting-point slag-forming agent provided by the present invention is conducive to slag-forming.

[0025] Furthermore, the acidic compound SiO2 in converter slag has the function of reducing the surface tension of FeO melt, while Al2O3 has the opposite effect, increasing the surface tension of converter slag, thus promoting the foaming of converter slag, better covering the converter smelting pool, and avoiding drying. In the double slag dephosphorization slag making process, this effect is more prominent, which is conducive to the foaming of converter slag in the dephosphorization stage, thereby increasing the volume of the slag layer and facilitating more discharge of converter slag from the furnace.

[0026] The TFe in the slagging agent provided by the present invention comes from 40%-60% of converter dust ash in the slagging agent. Controlling the TFe content at 25%-38% can not only promote the slagging of the slagging agent and improve the slagging rate, but also improve the utilization rate of the converter dust ash.

[0027] The present invention provides a converter slag-forming agent, the raw materials of which are all low-melting-point substances, without high-melting-point lime and quartz, and the TFe content in the slag-forming agent is relatively high, so the converter slag-forming agent provided by the present invention can quickly slag, and can improve the slag-forming efficiency and slag-forming effect. The melting point of FeO is 194°C lower than that of Fe2O3, so its slag-forming speed is about 1.4 times that of the commonly used Fe2O3 slag-forming agent ore. Due to its low-temperature rapid melting characteristics, the recycling rate of Fe in the slag-forming agent can be as high as more than 90%, which is particularly obvious in the double slag dephosphorization period, because the terminal temperature of the dephosphorization period is generally around 1420°C, which is higher than the melting temperature of FeO. FeO will melt at this temperature, but below the temperature of 1566°C of Fe2O3, there are obstacles to the melting of Fe2O3.

[0028] In addition, the slagging agent for a converter provided by the present invention uses converter dust removal ash and ladle casting slag as main raw materials, which not only solves the problem of recycling converter dust removal ash and ladle casting slag, but also the slagging agent contains 20%-30% CaO, which can reduce the amount of lime used in the converter smelting process, reduce production costs and improve economic benefits.

[0029] At the same time, the converter slag-forming agent provided by the present invention replaces the traditional F-containing slag-forming agent mainly composed of fluorite (CaF2). It not only has no obvious effect on the solubility of MgO in the converter slag, but also can reduce environmental pollution, reduce the erosion of the refractory materials of the furnace lining, increase the service life of the converter, and reduce production costs.

[0030] In addition, the present invention provides a method for preparing a converter slag-forming agent, which only requires ladle casting slag powder and converter dust ash as main raw materials, mixing them with a binder and water, pressing them into balls, and then drying them to obtain the converter slag-forming agent. It does not require mixing to prepare pre-melted slag under high temperature conditions, the preparation process is simple, energy can be saved, and the preparation cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flow chart of a method for preparing a converter slagging agent provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] A converter slag-forming agent provided in an embodiment of the present invention comprises, by mass percentage, 40%-60% of converter dust removal ash, 40%-60% of ladle casting slag and 4%-15% of binder, and the converter slag-forming agent components include TFe 25%-38%, CaO 20%-30%, Al2O3 15%-35%, SiO2 3%-8%, and MgO3%-5%.

[0033] Wherein, the TFe content of the converter dust is 40%-60%.

[0034] Wherein, in terms of mass percentage, the ladle casting slag components include CaO 30%-45%, Al2O3 25%-55%, MgO 4%-7%, TFe 0.5%-8%, and SiO2 5%-10%.

[0035] Wherein, the binder is a binder such as bentonite or magnesium chloride.

[0036] Since the steelmaking process requires the melting point of the slag to be 50℃-200℃ lower than the melting point of the steel being made, at a certain temperature, any component that can reduce the melting point of the slag and increase its concentration within a certain range can reduce the viscosity of the slag and promote slagging. FeO and Al2O3 can reduce the melting point of the slag. The more of these two, the better the slagging effect. When FeO and Al2O3 enter the slag, they need to melt quickly to promote the reaction. The lower the melting point of the added substance, the faster the reaction when entering the steel slag. Therefore, the higher the FeO content in the iron slag agent, the better the slagging effect of the iron slag agent, and the same is true for Al2O3. The converter slag-forming agent provided by the present invention is mainly iron with low-melting-point FeO, and its melting point is 1370°C, which is much lower than the melting point of Fe2O3 of 1566°C. The aluminum slag slag-forming agent contains up to 40%-60% of casting slag mainly composed of 12CaO·7Al2O3, and the melting point of 12CaO·7Al2O3 is 1392°C, which makes the melting point of the slag-forming agent lower. When slag-forming in the converter is difficult, the low-melting-point slag-forming agent can be quickly melted when added to the converter, and the unmelted slag dissolves into the liquid slag-forming agent to form low-melting-point converter slag. Therefore, the low-melting-point slag-forming agent provided by the present invention is conducive to slag-forming.

[0037] Therefore, the converter slag-forming agent provided by the present invention can quickly slag in converter smelting, and can greatly improve the slag-forming efficiency and slag-forming effect, because the raw materials are all low-melting-point substances, without high-melting-point lime and quartz, and the FeO content in the slag-forming agent is relatively high. The slag-forming agent provided by the present invention can quickly slag in converter smelting, and can greatly improve the slag-forming efficiency and slag-forming effect. Its slag-forming speed is about 1.4 times that of the commonly used slag-forming agent ore, and due to its low-temperature rapid melting characteristics, the recycling rate of Fe element in the slag-forming agent can be as high as more than 90%.

[0038] In addition, the slagging agent for a converter provided by the present invention uses converter dust removal ash and ladle casting slag as main raw materials, which not only solves the problem of recycling converter dust removal ash and ladle casting slag, but also the slagging agent contains 20%-30% CaO, which can reduce the amount of lime used in the converter smelting process, reduce production costs and improve economic benefits.

[0039] At the same time, the converter slag-forming agent provided by the present invention replaces the traditional F-containing slag-forming agent mainly composed of fluorite (CaF2). It not only has no obvious effect on the solubility of MgO in the converter slag, but also can reduce environmental pollution, reduce the erosion of the refractory materials of the furnace lining, increase the service life of the converter, and reduce production costs.

[0040] See also Figure 1 The present invention also provides a method for preparing a converter slag-forming agent, comprising the following steps:

[0041] Step 1) The raw materials are prepared according to 40%-60% of converter dust, 40%-60% of ladle casting slag and 4%-15% of binder in percentage by mass.

[0042] Step 2) crushing the ladle casting slag to obtain the ladle casting slag powder.

[0043] Wherein, the particle size of the converter dust is less than 1 mm. The particle size of the ladle casting slag powder is less than 3 mm.

[0044] Step 3) adding water to the ladle casting slag powder, converter dust removal ash and binder and mixing them evenly to obtain a mixture.

[0045] Step 4) pressing the mixture into balls to obtain finished balls.

[0046] Wherein, the diameter of the finished ball is 5-15cm.

[0047] Step 5) Dry and dehydrate the finished balls to obtain the converter slag-removing agent.

[0048] The water content of the finished ball after drying and dehydration is less than 2%.

[0049] The present invention provides a method for preparing a converter slag-forming agent, which only requires ladle casting slag powder and converter dust removal ash as main raw materials, a binder and water to mix, press into balls, and then air-dry or bake to obtain the converter slag-forming agent. It does not need to be mixed under high temperature conditions to prepare pre-melted slag, the preparation process is simple, energy can be saved, and the preparation cost is low.

[0050] The present invention provides a method for using a converter slag-forming agent, which comprises adding prepared converter slag-forming agent pellets into a converter silo, and adding the slag-forming agent into the converter for slag-forming according to the converter slag-forming situation at the initial stage of converter smelting and at various periods during the converter smelting process when slag-forming is required.

[0051] Among them, the slag agent can be added into the converter for slagging by a single slag method. The amount of slagging agent used during converter smelting is 5-25kg / ton of steel. The furnace temperature at the initial stage of converter smelting is 1300-1450°C, and 60%-70% of the total slagging agent is added at the initial stage of converter smelting; the furnace temperature during converter smelting is 1450-1650°C, and the remaining slagging agent is added in batches according to the converter slagging situation at each period of converter smelting. The slagging time after each addition of the slagging agent is 0.5-2min.

[0052] In addition, the double slag method can also be used to add slag agent into the converter for slagging. The amount of slag agent added during the dephosphorization period is determined according to the silicon conditions of the molten iron and the steel grade conditions. It is added when the basicity CaO / SiO2>1.4, and the comprehensive basicity Ca0 / (SiO2+Al2O3) is controlled between 1.4-2.0. Generally, 5-15kg / ton of steel is added. During the decarburization period, it is added 0.5-2min after the auxiliary materials are added, and 5-15kg / ton of steel is added to promote slag formation in the converter under low silicon conditions.

[0053] Example 1

[0054] In single slag smelting, 70% of the slag-removing agent is added to the converter through the converter silo at the beginning of converter smelting, and the remaining 30% of the slag-removing agent is added in batches according to the slag-removing situation in the middle and late stages of converter smelting. Under the same molten iron and auxiliary materials, TSC samples of the smelting process are taken, and the phosphorus content is determined by TSC analysis. The results are shown in Table 1. The P content of the test heat is 25.1% lower than that of the comparison heat.

[0055] Table 1 TSC sample P content determination results (%)

[0056]

[0057] Example 2

[0058] During double slag smelting, the amount of slag-removing agent added during the dephosphorization period is determined according to the silicon conditions of the molten iron and the conditions of the steel grade. It is added when the basicity CaO / SiO2>1.4, and the comprehensive basicity Ca0 / (SiO2+Al2O3) is controlled between 1.4-2.0. Generally, 5-15kg / ton of steel is added. As shown in Table 2, the converter inclination angle when the converter slag flows out of the furnace mouth during the slag pouring process is 69.8° for the test furnace and 76.5° for the comparison furnace. The test furnace is 6.7° smaller than the comparison furnace, and the slag foaming is better.

[0059] Table 2 Converter inclination angle when converter slag flows out from the furnace mouth during slag pouring (°)

[0060]

[0061] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A converter slag-removing agent, characterized in that: Calculated by mass percentage, it includes 40%-60% of converter dust removal ash, 40%-60% of ladle casting slag and 4%-15% of binder, and the converter slag-forming agent components include TFe 25%-38%, CaO 20%-30%, Al2O3 15%-35%, SiO2 3%-8%, and MgO3%-5%.

2. The converter slag-removing agent according to claim 1, characterized in that: The TFe content of the converter dust is 40%-60%.

3. The converter slag-removing agent according to claim 1, characterized in that: In terms of mass percentage, the ladle casting slag components include 30%-45% CaO, 25%-55% Al2O3, 4%-7% MgO, 0.5%-8% TFe, and 5%-10% SiO2.

4. The converter slag-removing agent according to claim 1, characterized in that: The binder includes bentonite or magnesium chloride.

5. A method for preparing a converter slag-forming agent according to any one of claims 1 to 4, characterized in that: The steps include: In terms of mass percentage, the raw materials are prepared according to 40%-60% of converter dust, 40%-60% of ladle casting slag and 4%-15% of binder; crushing the ladle casting slag to obtain the ladle casting slag powder; The ladle casting slag powder, converter dust removal ash and binder are mixed with water to obtain a mixture; Pressing the mixture into balls to obtain finished balls; The finished balls are dried and dehydrated to obtain the converter slag-removing agent.

6. The method for preparing a converter slag-removing agent according to claim 5, characterized in that: The particle size of the converter dust is less than 1 mm, and the particle size of the ladle casting slag powder is less than 3 mm.

7. The method for preparing a converter slag-removing agent according to claim 5, characterized in that: The diameter of the finished ball is 5-15 cm, and the water content of the finished ball after drying and dehydration is less than 2%.

8. A method for using a converter slag-removing agent, characterized in that: The converter slag-forming agent prepared according to claims 5-7 is added to the converter silo, and the slag-forming agent is added into the converter for slag-forming according to the converter slag-forming situation at the initial stage of converter smelting and at various periods during the converter smelting process when slag-forming is required.

9. The method for using the converter slag-removing agent according to claim 8, characterized in that: The slag-forming agent is added to the converter for slag forming by a single slag method, the amount of slag-forming agent used in converter smelting is 5-25kg / ton of steel, the furnace temperature in the initial stage of converter smelting is 1300-1450°C, and 60%-70% of the total slag-forming agent is added in the initial stage of converter smelting; the furnace temperature during converter smelting is 1450-1650°C, and the remaining slag-forming agent is added in batches according to the converter slag forming situation at each period during the converter smelting process when slag forming is required, and the slag forming time after each addition of the slag-forming agent is 0.5-2min.

10. The method for using the converter slag-removing agent according to claim 8, characterized in that: The slag-forming agent is added to the converter to form slag using the double slag method. The amount of slag-forming agent added during the dephosphorization period is determined according to the silicon conditions of the molten iron and the conditions of the steel grade. The slag-forming agent is added when the basicity CaO / SiO2>1.4, and the comprehensive basicity CaO / (SiO2+Al2O3) is controlled between 1.4 and 2.

0. The slag-forming agent is added during the decarburization period 0.5 to 2 minutes after the auxiliary materials are added, and 5 to 15 kg per ton of steel is added to promote slag-forming in the converter under low silicon conditions.

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