A method for gas generation in slag-reduced smelting under the condition of hot metal in a converter at high temperature

Abstract

The present application provides a method for gas generation in slag-reduced smelting under the condition of hot metal in a converter, which relates to the metallurgical field. The method includes: analyzing the hot metal entering the furnace to obtain the temperature and composition information of the hot metal, and classifying the hot metal entering the furnace according to the temperature and composition information; the temperature of the hot metal entering the furnace is greater than 1350 °C, and the silicon mass content is greater than 0.4%; determining the scrap ratio and using raw materials for converter charging; according to the classification result and the raw material composition, determining the blowing mode and the slag-making agent scheme, blowing a top-blown oxygen-carbon dioxide mixture and bottom-blowing carbon dioxide according to the blowing mode, and adding a solid slag-making agent according to the slag-making agent scheme, and obtaining a target steel product and recovered gas through converter smelting. The method provided by the present application reduces the amount of slag-making agent under the condition of reducing the converter slag, improves the steel yield, increases the gas recovery amount, and thus is beneficial to reducing the converter smelting cost.

Description

Technical Field

[0001] The present application relates to the metallurgical field, and particularly to a method for slag-reducing smelting and gas generation under the condition of high-temperature hot metal in a converter. Background Art

[0002] At present, the domestic iron and steel industry mainly adopts the long process of blast furnace-converter smelting, accounting for about 90% of the total iron and steel output value. Converter steelmaking mainly uses hot metal and scrap as raw materials, and top-blowing O2 reacts with elements such as [C], [Si], and [Mn] in the molten bath to provide heat to complete the steelmaking process. During the steelmaking process, slag-making agents such as lime, limestone, and sinter are added to make slag. The main purpose is to oxidize the impurity elements in the iron and steel materials into the slag for removal, and to control the temperature at the end of converter smelting to be relatively stable.

[0003] The blast furnace process is the main link in hot metal production and determines the quality of hot metal. In the actual production process, the iron and steel plant faces the choice of raw material composition fluctuations and cost levels, resulting in large fluctuations in the temperature and composition of the hot metal produced by the blast furnace process. When the temperature of the hot metal is relatively high or the silicon content is relatively high, a large amount of slag-making agent is required to balance the heat and maintain the slag basicity, resulting in an increase in the slag volume in the converter, which is not conducive to the smooth progress of the smelting process, an increase in splashing during converter smelting, an increase in iron loss in the slag, waste of hot metal heat, and an increase in the cost of converter smelting.

[0004] Based on this, it is necessary to develop a new converter smelting method to solve the above problems. Summary of the Invention

[0005] The purpose of the present application is to provide a method for slag-reducing smelting and gas generation under the condition of high-temperature hot metal in a converter to solve the above problems.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] A method for slag-reducing smelting and gas generation under the condition of high-temperature hot metal in a converter, comprising:

[0008] Analyze the hot metal entering the furnace, obtain the temperature and composition information of the hot metal, and classify the hot metal entering the furnace according to the temperature and composition information; the temperature of the hot metal entering the furnace is greater than 1350 °C and the silicon mass content is greater than 0.4%; the classification includes:

[0009] When the temperature of the hot metal entering the furnace is greater than 1400 °C and the silicon mass content is greater than 0.8%, it is high-temperature high-silicon hot metal; when the temperature of the hot metal entering the furnace is greater than 1400 °C and the silicon mass content is less than or equal to 0.8%, it is high-temperature low-silicon hot metal; when the temperature of the hot metal entering the furnace is greater than 1350 °C and less than or equal to 1400 °C and the silicon mass content is greater than 0.8%, it is low-temperature high-silicon hot metal;

[0010] Determine the scrap ratio and use raw materials for converter charging;

[0011] According to the classification results and the raw material composition, determine the injection mode and slag-forming agent scheme. Blow a mixture of oxygen and carbon dioxide from the top and carbon dioxide from the bottom according to the injection mode, and add solid slag-forming agents according to the slag-forming agent scheme. The converter smelting obtains the target steel product and the recycled gas.

[0012] Preferably, the scrap ratio is not higher than 20% of the total mass of the raw materials.

[0013] Preferably, in the oxygen-carbon dioxide mixture, the volume fraction of carbon dioxide is not higher than 50%.

[0014] Preferably, when the hot metal charged is high-temperature high-silicon hot metal, in the oxygen-carbon dioxide mixture, the volume fraction of carbon dioxide is 20%-40%;

[0015] When the hot metal charged is high-temperature low-silicon hot metal or low-temperature high-silicon hot metal, in the oxygen-carbon dioxide mixture, the volume fraction of carbon dioxide is not higher than 30%.

[0016] Preferably, the volume fraction of carbon dioxide in the oxygen-carbon dioxide mixture is determined by the following formula:

[0017] η(CO2) = w·(1 - η 废钢 )

[0018] In the formula, η(CO2) is the volume fraction of carbon dioxide, w is a proportionality constant, taking 0.32 - 0.36 for high-temperature high-silicon hot metal, and taking 0.14 - 0.18 for both high-temperature low-silicon hot metal and low-temperature high-silicon hot metal.

[0019] Preferably, the flow rate of the top blowing is 2000 Nm 3 / h - 10000 Nm 3 / h, and the flow rate of the bottom blowing is 120 Nm 3 / h - 480 Nm 3 / h.

[0020] Preferably, the solid slag-forming agents include hydrated lime, limestone and sinter.

[0021] Preferably, the determination process of the slag-forming agent scheme includes:

[0022] When the hot metal charged is the high-temperature high-silicon hot metal or the low-temperature high-silicon hot metal, based on reducing the amount of sinter used, adjust the amount of hydrated lime in combination with the basicity, and then adjust the amount of limestone with the goal of controlling the slag-making amount;

[0023] When the molten iron charged into the furnace is the high-temperature low-silicon molten iron, based on reducing the dosage of limestone, the dosage of hydrated lime is adjusted in combination with the basicity, and then the dosage of sinter is adjusted with the aim of controlling the slag-making amount.

[0024] Preferably, the binary basicity of the slag in the converter smelting is 2.1-2.8.

[0025] Preferably, the temperature of the molten iron in the converter smelting is 1350°C to 1500°C, and the blowing time is 11 minutes to 17 minutes.

[0026] Compared with the prior art, the beneficial effects of the present application include:

[0027] The method for less slag smelting and gas production under the condition of high-temperature molten iron in a converter provided by the present application classifies the molten iron according to the temperature and composition of the molten iron charged into the furnace; according to the classification results and raw material composition, appropriate amounts of slag-making agents such as lime, limestone, and sinter are selected and added, and CO2 is used as the gas coolant for converter smelting. By mixing CO2 when blowing O2 from the top, the control of the converter smelting temperature is achieved. As a coolant, CO2 can replace part of the slag-making agent to achieve less slag smelting in the converter, reduce the splashing iron loss during the smelting process, reduce the iron loss in the slag at the end of smelting, improve the steel yield, and increase the recovery amount of converter gas. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope of the present application.

[0029] Figure 1 It is a schematic flow chart of the less slag smelting process under the condition of high-temperature molten iron in a converter provided by the present application;

[0030] Figure 2 It is a gas supply curve graph of the less slag smelting and gas production process with CO2 injection in a 120t converter;

[0031] Figure 3 It is a gas supply curve graph of the less slag smelting and gas production process with CO2 injection in a 210t converter;

[0032] Figure 4 It is a gas supply curve graph of the less slag smelting and gas production process with CO2 injection in a 300t converter. Detailed Embodiments

[0033] In order to better explain the technical solutions provided by the present application, before the embodiments, the technical solutions will be presented as a whole as follows:

[0034] A method for less slag smelting and gas production under the condition of high-temperature molten iron in a converter, comprising:

[0035] Analyze the hot metal charged into the furnace to obtain the temperature and composition information of the hot metal, and classify the hot metal charged into the furnace based on the temperature and composition information; the temperature of the hot metal charged into the furnace is greater than 1350 °C, and the mass content of silicon is greater than 0.4%; the classification includes:

[0036] When the temperature of the hot metal charged into the furnace is greater than 1400 °C and the mass content of silicon is greater than 0.8%, it is high-temperature high-silicon hot metal; when the temperature of the hot metal charged into the furnace is greater than 1400 °C and the mass content of silicon is less than or equal to 0.8%, it is high-temperature low-silicon hot metal; when the temperature of the hot metal charged into the furnace is greater than 1350 °C and less than or equal to 1400 °C and the mass content of silicon is greater than 0.8%, it is low-temperature high-silicon hot metal;

[0037] Determine the scrap ratio and charge the converter with raw materials;

[0038] According to the results of the classification and the raw material composition, determine the blowing mode and slag-forming agent scheme. Blow a top-blown oxygen-carbon dioxide mixture and bottom-blow carbon dioxide according to the blowing mode, and add solid slag-forming agents according to the slag-forming agent scheme. The target steel product and recycled gas are obtained through converter smelting.

[0039] In the face of the increased pressure of the slag during the smelting of high-temperature hot metal, CO2 can be used as a gas coolant for converter smelting, and has the following advantages: (1) CO2 has reaction characteristics under the high-temperature conditions of the molten bath and can undergo oxidation reactions with elements such as [C], [Si], [Mn], and Fe(l) in the molten bath, and the reaction rate is above 80%; (2) Compared with O2, more CO gas is generated when CO2 reacts with the elements in the molten bath, which is conducive to improving the reaction kinetic conditions and can increase the heat recovered from converter gas; (3) The reaction of CO2 with [C] and Fe(l) in the molten bath is an endothermic reaction, and the reaction with [Si] and [Mn] is a slightly exothermic reaction, and the specific heat capacity of CO2 is higher than that of O2. Therefore, CO2 can be used as a gas coolant for converter smelting and does not introduce impurities such as SiO2, making it a clean coolant.

[0040] It should be noted that: after the blowing is completed, tilt the furnace to tap the steel. Argon is bottom-blown throughout the tapping process of the converter, and slag blocking operation is carried out to prevent pollution of the molten steel. After tapping, slag splashing for furnace protection is carried out, and the converter maintenance work is completed, and then the smelting of the next furnace is carried out.

[0041] Such as Figure 1As shown, generally speaking, the method provided by this application can achieve the purposes of reducing the splashing iron loss during the smelting process, reducing the iron loss in the slag at the end of smelting, and increasing the steel yield. By combining the molten iron temperature, composition information, and scrap ratio, the CO2 mixed blowing ratio and the dosage of various slag formers are determined respectively to complete the slag-reduced converter smelting process. First, the conditions of the molten iron entering the furnace are obtained and divided into three categories of high-temperature molten iron, namely high-temperature high-silicon, high-temperature low-silicon, and low-temperature high-silicon molten iron; with the scrap ratio fixed, the converter starts charging, and the O2-CO2 mixed blowing process is formulated based on the comprehensive scrap ratio and the heat of the molten iron; then, a reasonable slag-making process is selected by comprehensively considering the silicon content of the molten iron, the scrap ratio, and the CO2 dosage to complete the blowing process; finally, operations such as tapping the converter and slag splashing for furnace lining protection are completed.

[0042] The nominal capacity of the converter is generally 35 - 450t.

[0043] In an optional embodiment, the scrap ratio is not higher than 20% of the total mass of the raw materials.

[0044] The scrap ratio is determined based on the actual needs of each smelting scenario and cost control, etc.

[0045] In an optional embodiment, in the oxygen-carbon dioxide mixture, the volume percentage of carbon dioxide is not higher than 50%.

[0046] In an optional embodiment, when the molten iron entering the furnace is high-temperature high-silicon molten iron, in the oxygen-carbon dioxide mixture, the volume percentage of carbon dioxide is 20 - 40%;

[0047] When the molten iron entering the furnace is high-temperature low-silicon molten iron or low-temperature high-silicon molten iron, in the oxygen-carbon dioxide mixture, the volume percentage of carbon dioxide is not higher than 30%.

[0048] In an optional embodiment, the volume percentage of carbon dioxide in the oxygen-carbon dioxide mixture is determined by the following formula:

[0049] η(CO2) = w·(1 - η 废钢 )

[0050] In the formula, η(CO2) is the volume percentage of carbon dioxide, w is a proportionality constant, taking 0.32 - 0.36 for high-temperature high-silicon molten iron, and taking 0.14 - 0.18 for both high-temperature low-silicon molten iron and low-temperature high-silicon molten iron.

[0051] In an optional embodiment, the flow rate of the top blowing is 2000 Nm 3 / h - 10000 Nm 3 / h, and the flow rate of the bottom blowing is 120 Nm 3 / h - 480 Nm 3 / h.

[0052] In an alternative embodiment, the solid slag former includes hydrated lime, limestone and sinter.

[0053] In an alternative embodiment, the process for determining the slag former scheme includes:

[0054] When the hot metal charged into the furnace is the hot high-silicon hot metal or the cold high-silicon hot metal, based on reducing the amount of sinter, the amount of hydrated lime is adjusted in combination with the basicity, and then the amount of limestone is adjusted with the aim of controlling the slag amount;

[0055] When the hot metal charged into the furnace is the hot low-silicon hot metal, based on reducing the amount of limestone, the amount of hydrated lime is adjusted in combination with the basicity, and then the amount of sinter is adjusted with the aim of controlling the slag amount.

[0056] Reduce the amount of the corresponding solid slag former to make up for the heat consumption caused by blowing CO2.

[0057] Adding scrap steel, lime, limestone, sinter and blowing CO2 has a cooling effect on the molten bath. The cooling effects of different coolants and scrap steel are represented by L with the material subscript added, H 潜 represents the latent heat of fusion of scrap steel, H 分解 represents the endothermic decomposition of the slag former, H 反应 represents the endothermic reaction of CO2 with the elements in the molten bath, and its calculation formula is as follows:

[0058] L 废钢 = m 废钢 ×(c 废钢 ×(T 熔化 - T0) + H 潜 + c 钢水 ×(T 终点 - T 熔化 ))

[0059] L 造渣剂 = m 造渣剂 ×(H 分解 + c 造渣剂 ×(T 终点 - T0))

[0060] L CO2 = m CO2 ×(H 反应 + c CO2 ×(T 终点 - T0))

[0061] Taking the heat absorbed by the melting and heating of scrap steel as the equivalent value 1, the cooling effects of the slag former and CO2 relative to it are shown in Table 1.

[0062] Table 1 Cooling effects of each material

[0063] Item Scrap Steel Sintered Ore Limestone Lime <![CDATA[CO2]]> Equivalent Value 1.0 2.5～3.2 1.4～1.8 0.8～1 1.2～1.7

[0064] In an alternative embodiment, the binary basicity of the slag in the converter smelting is 2.1 - 2.8.

[0065] It is 0.2 - 0.8 lower than that of the conventional smelting process, and the lime consumption in the converter smelting is reduced.

[0066] In an alternative embodiment, the molten iron temperature in the converter smelting is 1350 °C to 1500 °C, and the blowing time is 11 minutes to 17 minutes.

[0067] The implementation scheme of the present application will be described in detail below in conjunction with specific embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are followed. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0068] First, industrial tests were carried out using the molten iron produced by a blast furnace in a domestic factory as raw materials, as follows:

[0069] The molten iron composition produced by the blast furnace of this factory is as shown in Table 2 below:

[0070] Table 2 Molten iron composition produced by the blast furnace

[0071] Unit Minimum Value Maximum Value Average Value Temperature ℃ 1370 1440 1405 C Wt% 4.24 5.12 4.68 Si Wt% 0.56 0.98 0.77 Mn Wt% 0.12 0.16 0.14

[0072] According to Table 2, it can be seen that the molten iron temperature and composition of this factory fluctuate greatly, covering three types of high-calorie molten iron, namely high-temperature high-silicon, high-temperature low-silicon, and low-temperature high-silicon. The slag-making agent and slag amount before using the method provided by the present application are shown in Table 3.

[0073] Table 3 Slag-making agent and slag amount before improvement

[0074]

[0075] According to the actual situation of the molten iron in this factory and in combination with the method provided by the present application, an industrial production comparative test was carried out, and the effects are shown in Table 4:

[0076] Table 4 Basic data of the comparison furnace

[0077]

[0078] As can be seen from Table 4, after applying the method of the present application, the lime consumption per ton of steel is reduced by 10.55 kg, the limestone consumption is reduced by 7.63 kg, the sinter ore consumption is reduced by 4.50 kg, the yield of steel slag per ton of steel is reduced by 27.89 kg, and the reduction effect of the converter smelting slag amount is significant. The average total iron content in the slag is 18%, and the metal yield per ton of steel is increased by 5.02 kg. The recovered gas volume per ton of steel is increased by 7.8 Nm 3 , and the CO concentration in the gas is increased by 6.22%.

[0079] To more comprehensively illustrate the method provided by the present application, the following examples are specifically provided:

[0080] Example 1

[0081] For a certain blast furnace hot metal in a 120t converter of a certain factory, a slag-free smelting process under the condition of high-temperature hot metal in the converter is as follows:

[0082] S1. Analyze the hot metal entering the furnace to obtain the temperature and composition information of the hot metal as follows:

[0083] Hot metal temperature: 1440 °C, hot metal Wt.[C]: 5.12%, hot metal Wt.[Si]: 0.98%, hot metal Wt.[Mn]: 0.16%, hot metal Wt.[P]: 0.11%, hot metal Wt.[S]: 0.020%; After judgment, the hot metal condition is high-temperature and high-silicon hot metal.

[0084] S2. When smelting in this converter, the scrap ratio in the steel and iron materials is 17%.

[0085] S3. According to the hot metal composition and the steel and iron material structure, formulate a top-blown O2-CO2 smelting mode. Overall, the proportion of CO2 in the O2 and CO2 mixed gas is 28.22%. Specifically, the flow curve diagram of the O2-CO2 mixed gas blown into the converter is as Figure 2 shown. The flow rate of top-blown CO2 is 4500 Nm 3 / h to 7500 Nm 3 / h, and the flow rate of bottom-blown CO2 is 120 Nm 3 / h.

[0086] When blowing the O2-CO2 gas mixture, the binary basicity of slag formation in the converter smelting is 2.7, which is 0.2 lower than that of the conventional smelting process.

[0087] The hot metal entering the furnace is determined to be high-temperature and high-silicon hot metal. By reducing the sinter ore consumption, the heat consumption caused by blowing CO2 is compensated, and the sinter ore addition amount per ton of steel is reduced by 5 - 7 kg.

[0088] S4. Tapping the converter, argon is blown from the bottom throughout the tapping process of the converter, and slag blocking operation is done well to prevent pollution of the molten steel.

[0089] S5. Slag splashing for furnace protection is carried out, and the converter maintenance work is completed, and then the smelting of the next heat is carried out.

[0090] The addition amount of slag-making agent and the slag output during smelting are counted, and the results are shown in Table 5:

[0091] Table 5 Comparison of high-temperature and high-silicon hot metal production

[0092]

[0093] As can be seen from Table 5, after the method provided in this application is applied, the lime consumption per ton of steel is reduced by 12.13 kg, the limestone consumption is reduced by 3.88 kg, the sinter ore consumption is reduced by 7.17 kg, and the output of steel slag per ton of steel is reduced by 29.87 kg. The total iron content in the slag is 17%, and the metal yield per ton of steel is increased by 5.08 kg.

[0094] According to the statistical data of the gas holder in the converter auxiliary workshop, after the application of this process, the recovered gas volume per ton of steel is increased by 10.6 Nm 3 , and the CO concentration in the gas is increased by 6.48%.

[0095] Example 2

[0096] For a certain kind of blast furnace hot metal in a 210t converter of a certain factory, a slag-reducing smelting process under the condition of high-temperature hot metal in the converter is as follows:

[0097] S1. Analyze the hot metal entering the furnace to obtain the following temperature and composition information of the hot metal:

[0098] Hot metal temperature: 1437 °C, hot metal Wt.[C]: 4.68%, hot metal Wt.[Si]: 0.62%, hot metal Wt.[Mn]: 0.16%, hot metal Wt.[P]: 0.12%, hot metal Wt.[S]: 0.020%; After judgment, this hot metal condition is high-temperature and low-silicon hot metal.

[0099] S2. When smelting in this converter, the scrap ratio in the steel and iron materials is 13%.

[0100] S3. According to the hot metal composition and the steel and iron material structure, a top-blown O2-CO2 smelting process is formulated. The proportion of CO2 in the O2 and CO2 mixed gas is 12.42%. Specifically, the flow curve of the O2-CO2 mixed gas blown into the converter is as Figure 3 shown. The flow rate of top-blown CO2 is 3000 Nm 3 / h to 6800 Nm 3 / h, and the flow rate of bottom-blown CO2 is 280 Nm 3 / h.

[0101] When blowing the O2-CO2 mixed gas, the binary basicity of slag making in the converter smelting is 2.7, which is 0.2 lower than that of the conventional smelting process.

[0102] The molten iron charged into the furnace is determined to be high-temperature and low-silicon molten iron. The heat consumption caused by blowing CO2 is compensated by reducing the amount of limestone used. The amount of limestone added per ton of steel is reduced by 10 - 12 kg.

[0103] S4. Tapping the converter. Argon is blown from the bottom throughout the tapping process of the converter, and slag blocking operation is carried out well to prevent the molten steel from being contaminated.

[0104] S5. Slag splashing for furnace lining protection, and completing the converter maintenance work, then proceeding with the smelting of the next furnace.

[0105] The addition amount of slag-making agent and the output of furnace slag during the smelting period are counted, and the results are shown in Table 6:

[0106] Table 6 Comparison of high-temperature and low-silicon molten iron production

[0107]

[0108] As can be seen from Table 6, after the application of the slag-reducing smelting process under the condition of high-temperature molten iron in the converter, the amount of lime used per ton of steel is reduced by 5.41 kg, the amount of limestone used is reduced by 11.31 kg, the amount of sinter used is reduced by 1.82 kg, and the output of steel slag per ton of steel is reduced by 14.83 kg. The total iron content is 18%, and the metal yield per ton of steel is increased by 2.67 kg.

[0109] According to the statistical data of the gas holder in the converter auxiliary workshop, after the application of the slag-reducing smelting process under the condition of high-temperature molten iron in the converter, the amount of gas recovered per ton of steel is increased by 6.1 Nm 3 , and the CO concentration in the gas is increased by 3.23%.

[0110] Example 3

[0111] For a certain type of blast furnace molten iron in a 300t converter of a certain factory, a slag-reducing smelting process under the condition of high-temperature molten iron in the converter is carried out as follows:

[0112] S1. Analyze the molten iron charged into the furnace to obtain the following temperature and composition information of the molten iron:

[0113] Molten iron temperature: 1370 °C, molten iron Wt.[C]: 4.65%, molten iron Wt.[Si]: 0.98%, molten iron Wt.[Mn]: 0.12%, molten iron Wt.[P]: 0.12%, molten iron Wt.[S]: 0.020%; After determination, the condition of this molten iron is low-temperature and high-silicon molten iron.

[0114] S2. During the smelting of this converter, the scrap ratio in the steel and iron materials is 15%.

[0115] S3. Based on the hot metal composition and the structure of steel materials, formulate the top-blown O2-CO2 smelting process. The proportion of CO2 in the O2 and CO2 mixed gas is 14.88%. Specifically, the flow curve diagram of the O2-CO2 mixed gas blown into the converter is as shown in Figure 4 shown. The flow rate of the top-blown CO2 is 6500 Nm 3 / h to 9000 Nm 3 / h, and the flow rate of the bottom-blown CO2 is 400 Nm 3 / h.

[0116] When blowing the O2-CO2 gas mixture, the binary basicity of slag formation in converter smelting is 2.8, which is 0.2 lower than that of the conventional smelting process.

[0117] The hot metal charged into the furnace is determined to be low-temperature and high-silicon hot metal. The heat consumption caused by blowing CO2 is compensated by reducing the amount of sinter added. The amount of sinter added per ton of steel is reduced by 4 - 6 kg.

[0118] S4. Tapping the converter. Argon is blown from the bottom throughout the tapping process of the converter, and slag blocking operation is carried out well to prevent contamination of the molten steel.

[0119] S5. Carry out slag splashing for furnace lining protection, complete the converter maintenance work, and then carry out the smelting of the next furnace.

[0120] Statistical data on the addition amount of slag formers and the output of furnace slag during smelting are shown in Table 7:

[0121] Table 7 Comparison of production of low-temperature and high-silicon hot metal

[0122]

[0123]

[0124] As can be seen from Table 7, after the application of the slag-reducing smelting process under the conditions of the high-temperature hot metal in the converter described above, the amount of lime used per ton of steel is reduced by 7.08 kg, the amount of limestone used is reduced by 2.23 kg, the amount of sinter used is reduced by 5.51 kg, and the output of steel slag per ton of steel is reduced by 17.93 kg. The total iron content in the slag is 19%, and the metal yield per ton of steel is increased by 3.41 kg.

[0125] According to the statistical data of the gas holder in the converter auxiliary workshop, after the application of the slag-reducing smelting process under the conditions of the high-temperature hot metal in the converter described above, the amount of recovered gas per ton of steel is increased by 7.8 Nm 3 , and the CO concentration in the gas is increased by 4.05%.

[0126] Comparative Example 1

[0127] In this Comparative Example 1, for a certain kind of blast furnace hot metal in a 120t converter of a certain factory, the traditional converter smelting process is adopted, that is, CO2 is not blown, and only slag formers are relied on to cool down the hot metal:

[0128] First, analyze the temperature and composition of the hot metal charged into the furnace. The information is as follows:

[0129] Hot metal temperature: 1420 °C, hot metal Wt.[C]: 4.89%, hot metal Wt.[Si]: 0.85%, hot metal Wt.[Mn]: 0.15%, hot metal Wt.[P]: 0.11%, hot metal Wt.[S]: 0.021%.

[0130] The scrap ratio in the steel materials during the smelting in this converter is 18%.

[0131] The slag-making basicity during smelting is 2.9. During the smelting process, lime, limestone, and sinter are added for slag-making.

[0132] Due to the relatively high temperature and large silicon content of the hot metal, the amount of slag-making agents added is very large. The lime consumption per ton of steel is 48.26 kg, the limestone consumption per ton of steel is 32.21 kg, and the sinter consumption per ton of steel is 11.52 kg.

[0133] During the smelting process, due to the too thick slag layer in the converter, serious splashing occurs during the blowing process. It is necessary to tilt the furnace to pour out the slag during the middle stage of smelting, and perform double-slag operation. This not only slows down the smelting rhythm but also causes losses of steel materials.

[0134] According to the statistical results of the converter slag in the slag car, when smelting hot metal at high temperature, the slag amount per ton of steel reaches 138.45 kg. The total iron content in the slag is 19%, and the metal yield per ton of steel is about 5.7 kg less than that of the slag-reducing smelting process under the conditions of high-temperature hot metal in one of the present inventions.

[0135] In addition, because the high heat of the high-temperature hot metal is mainly consumed by the slag-making agents, the calorific value of the converter gas has no obvious change, resulting in waste of heat.

[0136] Comparative Example 2

[0137] In this Comparative Example 2, for a certain blast furnace hot metal in a 150 t converter of a certain factory, the traditional converter smelting process is adopted, that is, no CO2 is blown, and only slag-making agents are relied on to cool down the hot metal:

[0138] First, analyze the temperature and composition of the hot metal charged into the furnace. The information is as follows:

[0139] Hot metal temperature: 1380 °C, hot metal Wt.[C]: 4.89%, hot metal Wt.[Si]: 0.95%, hot metal Wt.[Mn]: 0.15%, hot metal Wt.[P]: 0.11%, hot metal Wt.[S]: 0.021%.

[0140] The scrap ratio in the steel materials during the smelting in this converter is 16%.

[0141] The slag-making basicity during smelting is 2.7. During the smelting process, lime, limestone, and sinter are added for slag-making.

[0142] Due to the high temperature and large silicon content of the hot metal, the dosage of the slag-making agent added is very large. The lime dosage per ton of steel is 45.38 kg, the limestone dosage is 26.54 kg, and the sinter dosage is 14.21 kg.

[0143] During the smelting process, due to the too thick converter slag layer, serious splashing occurs during the blowing process. During the middle stage of smelting, operations such as raising the lance position and reducing the oxygen flow rate need to be taken, resulting in a reduction in the calorific value of the recovered gas, and serious splashing during the smelting process, causing losses of steel and iron materials.

[0144] According to the statistical results of the converter slag in the slag car, when smelting hot metal at high temperature, the slag amount per ton of steel reaches 156.49 kg. The total iron content in the slag is 22%, and the metal yield per ton of steel is about 8.2 kg less than that of the slag-reducing smelting process under the conditions of hot metal in a converter of the present invention.

[0145] In addition, because the high heat of the hot metal is mainly consumed by the slag-making agent, and the O2 intensity of blowing is reduced, the CO concentration in the gas is reduced by 2.11%, resulting in waste of heat.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for gas generation in slag-reduced smelting under the condition of hot metal in a converter, characterized in that, Including: Analyze the hot metal charged into the furnace to obtain the temperature and composition information of the hot metal, and classify the hot metal charged into the furnace according to the temperature and composition information; The temperature of the hot metal charged into the furnace is greater than 1350 °C, and the silicon mass content is greater than 0.4%; The classification includes: When the temperature of the hot metal charged into the furnace is greater than 1400 °C and the silicon mass content is greater than 0.8%, it is high-temperature and high-silicon hot metal. When the temperature of the hot metal charged into the furnace is greater than 1400 °C and the silicon mass content is greater than 0.4% and less than or equal to 0.8%, it is high-temperature and low-silicon hot metal. When the temperature of the hot metal charged into the furnace is greater than 1350 °C and less than or equal to 1400 °C and the silicon mass content is greater than 0.8%, it is low-temperature and high-silicon hot metal; Determine the scrap ratio and charge the converter with raw materials; According to the results of the classification and the raw material composition, determine the blowing mode and slag-forming agent scheme. Blow the top-blown oxygen-carbon dioxide mixture and bottom-blown carbon dioxide according to the blowing mode, and add solid slag-forming agent according to the slag-forming agent scheme to obtain the target steel product and recovered gas through converter smelting; The scrap ratio is not higher than 20% of the total mass of the raw materials; When the hot metal charged into the furnace is high-temperature and high-silicon hot metal, in the oxygen-carbon dioxide mixture, the volume ratio of carbon dioxide is 20-40%; When the hot metal charged into the furnace is high-temperature and low-silicon hot metal or low-temperature and high-silicon hot metal, in the oxygen-carbon dioxide mixture, the volume ratio of carbon dioxide is not higher than 30%; The solid slag-forming agent includes hydrated lime, limestone and sinter; The determination process of the slag-forming agent scheme includes: When the hot metal charged into the furnace is the high-temperature and high-silicon hot metal or the low-temperature and high-silicon hot metal, based on reducing the dosage of sinter, adjust the dosage of hydrated lime in combination with the basicity, and then adjust the dosage of limestone with the goal of controlling the slag amount; When the hot metal charged into the furnace is the high-temperature and low-silicon hot metal, based on reducing the dosage of limestone, adjust the dosage of hydrated lime in combination with the basicity, and then adjust the dosage of sinter with the goal of controlling the slag amount.

2. The method for slag-reduced smelting gas generation under the condition of hot metal in a converter according to claim 1, characterized in that In the oxygen-carbon dioxide mixture, the volume ratio of carbon dioxide is determined by the following formula: η(CO₂) = ω·(1 - η 废钢 ) Where η(CO2) is the volume percentage of carbon dioxide, ѡ is a proportionality constant, which is taken as 0.32 - 0.36 for high-temperature high-silicon hot metal, and 0.14 - 0.18 for both high-temperature low-silicon hot metal and low-temperature high-silicon hot metal; η 废钢 is the scrap ratio.

3. The method for slag-reducing smelting gas production under the condition of hot metal in a converter according to claim 1, characterized in that, The flow rate of the top blowing is 2000 Nm 3 / h to 12000 Nm 3 / h, and the flow rate of the bottom blowing is 120 Nm 3 / h to 480 Nm 3 / h.

4. The method for slag-reduced smelting gas production under the condition of hot metal in a converter according to claim 1, characterized in that The binary basicity of the slag in the converter smelting is 2.1-2.

8.

5. The method for slag-reduced smelting gas generation under the condition of hot metal in a converter at high temperature according to any one of claims 1-4, characterized in that, The hot metal temperature in the converter smelting is 1350 °C to 1500 °C, and the blowing time is 11 minutes to 17 minutes.

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