Method for preparing metallized sintered ore through electric induction heating and hydrogen reduction

Abstract

The invention discloses a method for preparing metallized sinter through electric induction heating and hydrogen reduction. The method comprises the steps that firstly, an iron ore raw material, a flux, fuel and return mine are mixed with water according to the proportion, granulation and ignition sintering are conducted, and hot-state sinter is obtained; and then the hot-state sintered ore is conveyed to an electric induction heating hydrogen reduction system, hydrogen-rich reducing gas is introduced, the hot-state sintered ore is sequentially conveyed to a hot-state sintered ore belt, an electric induction heating sintered ore belt and a hydrogen cooling sintered ore belt to react, and the cold-state metallized sintered ore is obtained. According to the method, in the reduction process, heat is provided by utilizing physical heat of the sinter and a mode of heating the metallized sinter through electric induction, the sinter is reduced into three sections including a hot sinter zone, an electric induction heating sinter zone and a hydrogen cooling sinter zone, and conditions of all the sections are synchronously optimized; and the reduction reaction efficiency, the metallization rate of the metallized sinter and the energy utilization efficiency of the whole process can be effectively improved, low-carbon emission in the reduction process is achieved, and the method is suitable for application and popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a method for preparing metallized sintered ore by electric induction heating and hydrogen reduction. Background Art

[0002] The long blast furnace-converter process dominates steel production. The preparation of green, low-carbon charge materials is a key approach to reducing carbon emissions in the steel industry. Theoretical and practical applications of blast furnace processes have shown that using 100% pre-reduced charge materials with a 70% reduction degree can reduce the fuel ratio by approximately 11.5%. To increase the metallization rate of incoming feedstock, researchers have proposed a process for pre-reducing sintered ore. Pre-reduced sintered ore shifts the iron ore reduction step earlier in the sintering process, allowing over 40% of the reduction to occur in the sintering machine. This reduces the reduction load on the blast furnace and reduces overall CO2 emissions from the ironmaking process.

[0003] Currently, research on pre-reduction sintering processes focuses on preparing carbon-containing pellets by mixing iron ore fines with solid fuel, followed by sintering. Some studies have employed a single-step roasting process to achieve both sintering and pre-reduction of fine-grained materials. This involves mixing iron ore fines with pulverized coal, pelletizing them to produce 5-6mm green pellets, which are then coated with iron ore fines to a diameter of 10mm before sintering. One study, using a sintering cup test, demonstrated pre-reduction sintering of a high-grade fine ore, achieving a metallization ratio of 45.7%.

[0004] Then, the existing pre-reduction sintering process still needs to solve the following key restrictive difficulties: First, the pre-reduction sintered ore is prone to over-melting; the pre-reduction sintered ore requires a reduction degree of 40-70% in an oxidizing atmosphere, and the quality of the sintered ore must be guaranteed; the appropriate proportion of solid fuel is difficult to control, if the proportion is too low, the reduction degree of the sintered ore is too low, and if the proportion is too high, the sintered ore is over-melted, affecting the quality; Second, the pre-reduction sintered ore is easy to re-oxidize; the hot pre-reduction sintered ore is in an oxidizing atmosphere on the sintering machine trolley and is easily oxidized again, and the reduction degree will be reduced, which will cause energy waste and affect the quality; Third, the flue gas has a high CO content; the pre-reduction sintering process uses solid fuel to reduce iron ore, and a large amount of high-CO flue gas will be generated in the process, which makes flue gas treatment difficult and costly.

[0005] In response to this, researchers have proposed using hydrogen-containing gas instead of carbon as a reducing agent to prepare metallized sintered ore. For example, Chinese patent applications CN114058840A, CN115491454A, and CN112159880A all propose pre-reducing iron ore with hydrogen-rich gas to produce metallized furnace charge with a certain metallization rate and good metallurgical properties. When using hydrogen-rich gas to reduce iron ore, hydrogen absorbs a large amount of heat during the reduction process. To maintain the required temperature for the reduction reaction, the gas typically needs to be repeatedly heated or supplemented with solid fuel combustion. This results in low hydrogen utilization and energy efficiency throughout the entire process, and the resulting furnace charge has a low metallization rate.

[0006] Therefore, it is necessary to develop a new process for preparing metallized furnace charges by hydrogen reduction to solve the reaction engineering problem of mismatch between physical energy and chemical energy caused by the strong endothermic effect of H2 reduction of iron oxides, and to break through the technical bottlenecks of low hydrogen utilization rate, low metallization rate and high energy consumption in the reduction process of traditional hydrogen-rich reduction to prepare pre-reduction furnace charges, so as to create favorable conditions for low-carbon and efficient preparation of metallized sintered ore and reduction of carbon emissions in the steel industry. Summary of the Invention

[0007] The main purpose of the present invention is to address the problems and shortcomings of the existing technology and provide a method for preparing metallized sintered ore by electric induction heating and hydrogen reduction, so as to solve the reaction engineering problem of mismatch between physical energy and chemical energy caused by the strong endothermic effect of H2 reduction of iron oxides, and prepare metallized sintered ore with a metallization rate of more than 50%. It effectively breaks through the technical bottlenecks of low hydrogen utilization rate, low metallization rate and high energy consumption of the reduction process in the preparation of pre-reduction charge with hydrogen-rich reduction, and creates favorable conditions for low-carbon and high-efficiency preparation of metallized sintered ore and reduction of carbon emissions from the steel industry.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A method for preparing metallized sintered ore by electric induction heating and hydrogen reduction comprises: mixing iron ore with flux and fuel and roasting to prepare sintered ore; reducing the resulting hot sintered ore using hydrogen-rich gas; the reduction process utilizes the physical heat of the sintered ore itself and electric induction heating of the metallized sintered ore to provide heat; the sintered ore reduction is divided into three stages: a hot sintering zone, an electric induction heating sintering zone, and a hydrogen cooling sintering zone; and simultaneously optimizing process parameters to optimize the reduction reaction efficiency, achieve low carbon emissions during the reduction process, and obtain sintered ore with a certain metallization rate. The specific technical solutions adopted by the present invention are as follows:

[0010] 1) Mixing the iron ore raw material with flux, fuel, and return ore in proportion with water, and pelletizing or pelletizing to obtain a mixture; distributing the mixture to a sintering machine through a distributor, igniting and sintering to obtain hot sintered ore;

[0011] 2) The hot sintered ore is crushed and screened and then transported to an electric induction heating hydrogen reduction system, where hydrogen-rich reducing gas is introduced. The hot sintered ore reacts in the electric induction heating hydrogen reduction system in sequence, which is divided into a hot sintering ore zone, an electric induction heating sintering ore zone, and a hydrogen cooling sintering ore zone to obtain cold metallized sintered ore.

[0012] In the above scheme, the raw materials in step 1) and their mass percentages include: 56.0-62.0% iron ore, 25-30% return ore, 9.0-12.0% flux, and 3.50-4.0% fuel.

[0013] In the above scheme, the iron ore raw material is mixed with flux, fuel, return ore and water, and the amount of water added is adjusted so that the moisture accounts for 5-7% of the total mass of the raw material.

[0014] Preferably, the iron ore is one or more of limonite, magnetite, hematite and the like.

[0015] Preferably, the flux is one or more of quicklime, dolomite, limestone, etc.

[0016] Preferably, the fuel is one or more of coke powder, anthracite, etc.

[0017] In the above scheme, the sintering machine adopts a micro-negative pressure ignition process for sintering ignition, the ignition temperature is 1050-1250°C, the furnace pressure is a micro-negative pressure (-6--12kPa), and the ignition time is 1-2min.

[0018] In the above scheme, the main components in the hot sintered ore and their mass percentages include: TFe 54-59%, SiO2 4.7-5.5%, and CaO 8-12%.

[0019] In the above scheme, the particle size of the hot sintered ore after crushing, screening and granulation is controlled at 10 to 30 mm, and the temperature is above 800°C.

[0020] In the above scheme, the sintered ore is crushed and screened and then transported to the electric induction heating hydrogen reduction system through a high-temperature resistant sealed pipeline.

[0021] In the above scheme, the electric induction heating hydrogen reduction system includes an electric induction heating device, a belt conveyor, a high-temperature and high-pressure sealed furnace, an electric induction heating device, a pressurized blower, a hydrogen-rich reducing gas pipeline, and an exhaust gas delivery pipeline. The high-temperature and high-pressure sealed furnace can also be a hydrogen-based vertical furnace.

[0022] In the above scheme, the reaction process of sintered ore with reducing gas in the electric induction heating hydrogen reduction system is divided into three stages: hot sintering zone, electric induction heating sintering zone, and hydrogen cooling sintering zone. In the hot sintering zone, the hot sintered ore roasted in the sintering machine is transported to the hydrogen reduction system via a high-temperature sealed pipeline. The high-temperature sintered ore, which is above 800°C, reacts with the reducing gas, gradually decreasing the sintered ore temperature and increasing the metallization rate. As the reduction reaction proceeds, the metallization rate reaches above 45%, and the temperature drops below 400°C. In the electric induction heating sintering zone, when the sintered ore temperature drops below 400°C, it is heated by an electric induction coil, raising the sintered ore temperature back to above 800°C (800-1100°C). In the hydrogen cooling sintering zone, the sintered ore temperature rises to above 800°C and continues to undergo reduction reaction with the reducing gas. As the H2 reduces the iron oxides with a strong endothermic reaction, the sintered ore temperature drops below 200°C, and the metallization rate increases to above 55%. In the above scheme, the induction heating device provided by the present invention performs induction heating on the high-metallization sintered ore. The induction heating device places an induction coil in the middle and rear portion of the sealed furnace and heats the high-metallization sintered ore using a medium-frequency current through the induction coil. The medium-frequency power supply has a power of 15,000 to 25,000 kW.

[0023] In the above scheme, the temperature of the sintered ore in the hot sintering zone is controlled above 800°C (the hot sintered ore obtained by sintering is directly transferred to the hydrogen reduction system without cooling), fully utilizing the physical heat of the sintered ore for the hydrogen reduction reaction. The induction heating device is used to heat the sintered ore with a high metallization rate, and the sintered ore temperature in the induction heating sintering zone is controlled between 800°C and 1100°C. Excessive temperatures can lead to excessive charge adhesion and cause abnormal furnace conditions, while low temperatures can reduce the efficiency of the reduction reaction. The temperature of the sintered ore in the hydrogen-cooled sintering zone is controlled below 200°C to ensure the full progress of the reduction reaction.

[0024] In the above scheme, the hydrogen-rich reducing gas can be one or more hydrogen-containing gases such as hydrogen, coke oven gas, blast furnace gas, etc., wherein the hydrogen content is above 35 vol%; the gas flow rate of the hydrogen-rich reducing gas is 0.5-3.0 m / s.

[0025] Furthermore, the hydrogen-rich reducing gas passes through a hydrogen-cooled sintering zone, an electric induction-heated sintering zone and a hot-state sintering zone in sequence.

[0026] Furthermore, the hydrogen content of the hydrogen-rich reducing gas in the hot sintering zone is more than 55 vol%; the hydrogen content of the hydrogen-rich reducing gas in the electric induction heating sintering zone is more than 40 vol%; the hydrogen content of the hydrogen-rich reducing gas in the hydrogen cooling sintering zone is more than 35 vol%.

[0027] Preferably, the flow rate of the hydrogen-rich reducing gas in the hot sintering zone is 2.0-3.0 m / s, the flow rate of the hydrogen-rich reducing gas in the electric induction heating sintering zone is 1.0-2.0 m / s, and the flow rate of the hydrogen-rich reducing gas in the hydrogen cooling sintering zone is 0.5-1.0 m / s.

[0028] The hydrogen content and gas flow rate of the hydrogen-rich reducing gas are changed in the reaction section by adjusting the reducing gas ratio and the blast pressure.

[0029] Furthermore, in the electric induction heating hydrogen reduction system, the reaction time of the sintered ore in the hot sintering zone, the electric induction heating sintering zone, and the hydrogen cooling sintering zone are 30 to 120 minutes, 30 to 60 minutes, and 30 to 60 minutes, respectively.

[0030] In the above scheme, the tail gas generated by the electric induction heating hydrogen reduction system is returned to the hydrogen reduction system for circulation after purification.

[0031] In the above scheme, the obtained cold metallized sintered ore is transported to the blast furnace ironmaking section through the metallized sintered ore transportation system.

[0032] In the above scheme, the exhaust gas is purified of particulate matter and moisture through an electrostatic precipitator and a flue gas scrubber for recycling; if the hydrogen-rich reducing gas contains coke oven gas or blast furnace gas, the exhaust gas also needs to be free of CO2, and activated carbon adsorption or lime spraying can be used to remove CO2 from the flue gas.

[0033] In the above scheme, the temperature of the obtained cold metallized sintered ore is below 200°C, the metallization rate is above 55%, and the hydrogen utilization rate of the whole process is above 68%.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The method of the present invention first adopts a sintering machine to prepare sintered ore, which is then crushed and screened and transported to an electric induction heating hydrogen reduction system. The hot sintered ore and hydrogen-rich reducing gas undergo a gas-solid countercurrent reduction reaction (the conveying direction of the sintered ore is opposite to the direction of introduction of the hydrogen reducing gas). At the same time, an electric induction heating device is used to induction heat the sintered ore with a high metallization rate, thereby effectively solving the reaction engineering problem of the mismatch between physical energy and chemical energy caused by the strong endothermic effect of H2 reducing iron oxides. Metallized sintered ore with a metallization rate of more than 55% is prepared, breaking through the technical bottlenecks of low hydrogen utilization rate, low metallization rate and high energy consumption in the reduction process of hydrogen-rich reduction of pre-reduction furnace charge, and creating favorable conditions for low-carbon and high-efficiency preparation of metallized sintered ore and reducing carbon emissions in the steel industry.

[0036] (2) The method of the present invention can effectively simplify the process flow of metallized sintered ore, and divide the reduction of sintered ore into three sections: hot sintered ore zone, electric induction heating sintered ore zone, and hydrogen cooling sintered ore zone. First, the hot sintered ore is directly involved in the reduction reaction, and the physical heat of the roasted sintered ore is fully utilized. In the later stage of reduction, the metallized sintered ore is cooled by reducing the heat with hydrogen-rich gas, and the process conditions such as sintered ore temperature, gas hydrogen content, and gas flow rate during the reaction are simultaneously optimized, thereby effectively improving the reduction reaction efficiency and the energy utilization efficiency of the entire process, and having certain economic benefits.

[0037] (3) The present invention uses hydrogen-rich gas instead of traditional carbon-containing fuel. In view of the strong endothermic property of hydrogen-rich gas during reduction, the metallized sintered ore is supplemented with heat by an electric induction heating device. During the process, the heat can be adjusted according to the degree of reduction. The temperature of the prepared metallized sintered ore is lower than 200°C and it is directly transported to a blast furnace or a converter through a high-temperature resistant pipeline. This solves the problems of over-melting and reoxidation of the metallized sintered ore caused by heat mismatch in the traditional method, and at the same time avoids wear and breakage in subsequent processing, thereby improving the utilization efficiency of iron ore resources.

[0038] (4) The present invention uses hydrogen-rich gas as reducing gas, and the reduced tail gas can be recycled after removing CO2, H2O and dust, thus solving the problem of large amounts of NO in the flue gas of traditional solid fuel combustion. x 、SO x , CO, and dioxins are difficult to remove. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a system diagram of the method for preparing metallized sintered ore by electric induction heating and hydrogen reduction according to the present invention;

[0040] Figure 2 This is a schematic structural diagram of the induction heating hydrogen reduction system of the present invention;

[0041] In the figure, 1. hot sintering belt, 2. electric induction heating sintering belt, 3. hydrogen cooling sintering belt, 4. electric induction heating device, 5. belt conveyor, 6. high temperature and high pressure sealed furnace, 7. electric induction heating device, 8. first pressurized fan and reducing gas pipeline, 9. second pressurized fan and reducing gas pipeline, 10. third pressurized fan and reducing gas pipeline, 11. exhaust gas conveying pipeline. DETAILED DESCRIPTION

[0042] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0043] like Figure 1As shown, the present invention provides a method for preparing metallized sintered ore by electric induction heating and hydrogen reduction, comprising a belt roasting system, an electric induction heating and hydrogen reduction system, a metallized sintered ore transportation system, and a flue gas purification and circulation system; the specific control steps are as follows:

[0044] (1) Belt roasting system;

[0045] The belt roasting system is used to roast iron ore raw materials with flux, fuel, and return ore on a belt roaster to prepare sintered ore. The hot sintered ore is crushed and screened and then transported to the electric induction heating hydrogen reduction system through a high-temperature resistant sealed pipeline;

[0046] In a further preferred embodiment, the particle size of the hot sintered ore after crushing, screening and granulation is controlled to be 10 to 30 mm, and the metallization rate of the pre-reduced sintered ore is more uniform;

[0047] (2) Electric induction heating hydrogen reduction system:

[0048] In the electric induction heating hydrogen reduction system, the pre-reduction of the sintered ore is achieved through the gas-solid countercurrent reaction between the hot sintered ore and the hydrogen-rich reducing gas. Since the reduction of iron oxides by H2 is a strong endothermic reaction, the physical heat of the hot sintered ore itself is not enough to support the efficient reduction reaction. In response to the above problems, the present invention divides the reaction of sintered ore and reducing gas into three stages in the electric induction heating hydrogen reduction system, namely, the hot sintered ore zone 1, the electric induction heating sintered ore zone 2, and the hydrogen cooling sintered ore zone 3. In the electric induction heating sintered ore zone, an electric induction heating device is used to induction heat the sintered ore to supplement the heat, so as to solve the engineering problem of mismatch between physical energy and chemical energy caused by the strong endothermic reaction of H2 reducing iron oxides. Combined with Figure 2 As shown, the electric induction heating hydrogen reduction system includes an electric induction heating device 4, a belt conveyor 5, a high-temperature and high-pressure sealed furnace 6, an electric induction heating device 7, a first pressurized fan and a reducing gas pipeline 8, a second pressurized fan and a reducing gas pipeline 9, a third pressurized fan and a reducing gas pipeline 10, and an exhaust gas conveying pipeline 11.

[0049] The electric induction heating hydrogen reduction system may also adopt a vertical furnace process, with an electric induction heating device added to the lower part of the vertical furnace.

[0050] In the hot sintering zone, the hot sintered ore at the tail of the sintering machine is transported to the hydrogen reduction system via a high-temperature sealed pipeline. The high-temperature sintered ore, exceeding 800°C, reacts with the reducing gas, gradually decreasing the sintered ore temperature and increasing the metallization rate. As the reduction reaction proceeds, the metallization rate reaches over 45%, and the temperature drops below 400°C. The sintered ore is then transported to the induction heating sintering zone, where it is heated by an induction coil, raising the sintered ore temperature back to 800°C to 1100°C. The sintered ore is then transported to the hydrogen cooling sintering zone, where it continues to undergo a reduction reaction with the reducing gas. As the H2 reduces iron oxides in a strongly endothermic reaction, the sintered ore temperature drops below 200°C, and the metallization rate increases to over 55%. The reaction times for the sintered ore in the hot sintering zone, the induction heating sintering zone, and the hydrogen cooling sintering zone are 90 minutes, 45 minutes, and 45 minutes, respectively. The reducing gas is pure hydrogen, which is pressurized by the pressure blower and reducing gas pipes 8, 9, and 10 and then enters the electric induction heating hydrogen reduction system. The hydrogen content and gas flow rate are changed by adjusting the reducing gas component ratio and blast pressure.

[0051] The reducing gas passes through the hydrogen-cooled sintering zone, the induction-heated sintering zone, and the hot sintering zone in sequence. The reducing gas is heated by the high-temperature sintered ore and simultaneously undergoes a reduction reaction with the high-temperature sintered ore. The volume fraction of H2 in the reducing gas continues to decrease, while the volume fraction of H2O continues to increase. After the reduction reaction is completed, the reducing tail gas, under the action of the negative pressure blower, passes through the tail gas conveying pipe 11 into the flue gas purification circulation system to remove H2O and dust, and then passes through the first pressurized blower and the reducing gas pipe 8-10 again to participate in the reduction reaction. The reducing gas can also be coke oven gas. The reducing tail gas needs to remove CO2, H2O and dust when entering the flue gas purification circulation system, and then passes through the reducing gas pipe 8-10 again to participate in the reduction reaction.

[0052] (3) Metallized sintered ore transportation system:

[0053] The metallized sintered ore transportation system is used to transport metallized sintered ore with a temperature below 300°C and a metallization ratio of 50% or more to a blast furnace for ironmaking. The metallized sintered ore can be transported to the blast furnace via a sealed belt conveyor. A small amount of nitrogen can be introduced during transportation to prevent reoxidation of the metallized sintered ore.

[0054] (4) Flue gas purification circulation system:

[0055] The flue gas purification circulation system adopts an electrostatic precipitator and a flue gas scrubber to remove H2O and dust. If CO2 needs to be removed, a small amount of lime can also be sprayed in the scrubber to remove CO2 from the flue gas.

[0056] In the following examples, the iron ore raw material used has a chemical composition of TFe 61.14%, SiO2 4.75%, and CaO 0.80%; the fluxes include limestone, dolomite, and quicklime, with the limestone containing 53.29% CaO and 0.63% MgO, the dolomite containing 31.72% CaO and 18.44% MgO, and the quicklime containing 90.23% CaO and 1.38% MgO; the fuel is coke powder, which has an ash content of 12.38%, fixed C 86.59%, and volatile matter of 1.03%; and the return ore has a composition of TFe 58.50%, CaO 8.56%, and SiO2 4.74%. Iron ore raw material, flux, fuel, return ore, bed material, and water are mixed in the mass percentages of 53%, 7%, 3%, 24%, 6%, and 7%. The resulting mixture is granulated (average particle size after granulation is 4.3 mm) and then spread into a sintering machine through a distribution device for ignition and sintering. The ignition temperature is 1150°C and the ignition time is 1.5 minutes to obtain sintered ore (the main chemical components of the sintered ore are TFe 56.63%, SiO2 5.01%, and CaO 9.27%). The obtained sintered ore is crushed and screened (the particle size of the hot sintered ore after crushing, screening, and granulation is controlled to be 10-30 mm, and the temperature is higher than 900°C).

[0057] Example 1

[0058] A method for preparing metallized sintered ore by electric induction heating and hydrogen reduction comprises the following steps:

[0059] 1) The hot sintered ore after crushing and screening is transported to the electric induction heating hydrogen reduction system through a high-temperature resistant sealed pipeline. In the hot sintering ore belt, the average hydrogen content of the hydrogen-rich reducing gas is 55vol%, and the gas flow rate of the hydrogen-rich reduction is 2.0-3.0m / s. As the reduction reaction proceeds, the metallization rate of the sintered ore reaches 45-47.25%, and the temperature drops to 380-400℃; in the electric induction heating sintering ore belt, an induction coil is set at the rear of the sealed furnace, and the sintered ore with high metallization rate is heated by the medium frequency current through the induction coil. The medium frequency power supply power is 18000kw, and the hydrogen-rich reducing gas is heated in the electric induction heating sintered ore. The average hydrogen content in the zone is 40 vol%, and the gas flow rate of hydrogen-rich reduction is 1.0-2.0 m / s. After heating, the sintered ore temperature rises again to 810-895°C, and the metallization rate reaches 47.5-52.5%. In the hydrogen-cooled sintering zone, the average hydrogen content in the hydrogen-rich reduction gas is 35 vol%, and the gas flow rate of hydrogen-rich reduction is 0.5-1.0 m / s. After the reduction reaction, the metallized sintered ore temperature is 180°C, the metallization rate is 65%, and the hydrogen utilization rate of the whole process is 48%. The flue gas is collected through the exhaust gas transmission pipeline to the flue gas purification circulation system, and the electrostatic precipitator and flue gas scrubber remove H2O and dust in the flue gas, and the lime spray removes CO2 and NO in the flue gas. x 、SO x , the total CO content is less than 0.5 vol%.

[0060] 2) The obtained metallized sintered ore is transported to the blast furnace ironmaking section using a metallized sintered ore transportation system.

[0061] When 30% sintered ore with a metallization rate of 65% is added to the blast furnace, the coke ratio of the blast furnace decreases by about 12.5% ​​and the reduction pulverization rate of the blast furnace charge decreases by 5%.

[0062] Example 2

[0063] A method for preparing metallized sintered ore by electric induction heating and hydrogen reduction comprises the following steps:

[0064] 1) The hot sintered ore after crushing and screening is transported to the electric induction heating hydrogen reduction system through a high-temperature resistant sealed pipe. In the hot sintering ore belt, the average hydrogen content of the hydrogen-rich reducing gas is 60vol%, and the gas flow rate of the hydrogen-rich reduction is 2.0-3.0m / s. As the reduction reaction proceeds, the metallization rate of the sintered ore reaches 47.5-52.5%, and the temperature drops to 335-360℃; in the electric induction heating sintering ore belt, an induction coil is set at the rear of the sealed furnace, and the sintered ore with high metallization rate is heated by the medium frequency current through the induction coil. The medium frequency power supply power is 20000kw, and the hydrogen-rich reducing gas is heated in the electric induction heating sintering The average hydrogen content in the ore belt is 45 vol%, and the gas flow rate of hydrogen-rich reduction is 1.0-2.0 m / s. After heating, the sintered ore temperature rises again to 810-895°C, and the metallization rate reaches 52.3-57.8%. In the hydrogen-cooled sintered ore belt, the average hydrogen content in the hydrogen-rich reduction gas is 40 vol%, and the gas flow rate of hydrogen-rich reduction is 0.5-1.0 m / s. After the reduction reaction, the metallized sintered ore temperature is 150°C, the metallization rate is 70%, and the hydrogen utilization rate of the whole process is 55%. The flue gas is collected through the tail gas transmission pipeline to the flue gas purification circulation system, and the electrostatic precipitator and flue gas scrubber remove H2O and dust in the flue gas, and the lime spray removes CO2 and NO in the flue gas. x 、SO x , the total CO content is less than 0.5 vol%.

[0065] 2) The obtained metallized sintered ore is transported to the blast furnace ironmaking section using a metallized sintered ore transportation system.

[0066] When 30% sintered ore with a metallization rate of 70% is added to the blast furnace, the coke ratio of the blast furnace decreases by about 14% and the reduction pulverization rate of the blast furnace charge decreases by 6%.

[0067] Comparative Example 1

[0068] A method for preparing metallized sintered ore by hydrogen reduction is substantially the same as that of Example 1, except that the crushed and screened hot sintered ore is transported to a sealed system via a high-temperature resistant sealed pipe; a hydrogen-rich reducing gas having a hydrogen content of 55 vol% is introduced into the sealed system, and the gas flow rate of the hydrogen-rich reducing gas is 2.5 m / s.

[0069] The results show that as the reduction reaction proceeds, the metallization rate of the sintered ore reaches 15% and the temperature drops to 150℃.

[0070] Comparative Example 2

[0071] A method for preparing metallized sintered ore by electric induction heating and hydrogen reduction, the method being substantially the same as Example 1, except that the hot sintered ore after crushing and screening is transported to a sealed system via a high-temperature resistant sealed pipe; wherein the hydrogen content of the hydrogen-rich reducing gas during the entire reduction process is 60 vol%, the gas flow rate of the hydrogen-rich reduction is 3.0 m / s, and the sintered ore is heated throughout the reduction process via an induction coil using a medium-frequency current, and the medium-frequency power supply has a power of 18,000 kW.

[0072] The sintering results show that the above scheme obtains a metallized sintered ore with a temperature of 280°C, a metallization rate of 30%, a hydrogen utilization rate of 20% in the whole process, and 30% of the sintered ore with a metallization rate of 30% is added to the blast furnace. The coke ratio of the blast furnace decreases by about 4.5%, and the reduction pulverization rate of the blast furnace charge decreases by 3%.

[0073] The present invention adopts a reduction process based on electric induction heating and hydrogen reduction system, divides the sinter reduction into three sections: hot sinter zone, electric induction heating sinter zone, and hydrogen cooling sinter zone, and simultaneously optimizes the sinter temperature, gas hydrogen content, and gas flow rate process parameters during the reaction process. The electric induction heating process is matched with the reaction heat distribution, which can significantly improve the reduction reaction efficiency, increase the metallization rate of the metallized sinter, and improve the energy utilization efficiency of the entire process. Simply introducing electric induction heating to supplement the heat required for the hydrogen reduction process of the sinter cannot achieve the goal of efficiently preparing metallized sinter.

[0074] Obviously, the above embodiments are merely examples for illustrative purposes and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. However, any obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing metallized sintered ore by electric induction heating and hydrogen reduction, characterized in that: The steps include: 1) Mixing the iron ore raw material with flux, fuel, and return ore in proportion with water, and granulating or pelletizing to obtain a mixture; igniting and sintering the mixture to obtain hot sintered ore; 2) Crushing and screening the hot sintered ore and then conveying it to an electric induction heating hydrogen reduction system, wherein the electric induction heating hydrogen reduction system is divided into a hot sintering ore zone, an electric induction heating sintering ore zone, and a hydrogen cooling sintering ore zone; hydrogen-rich reducing gas is introduced, and the hot sintered ore is conveyed to the hot sintering ore zone, the electric induction heating sintering ore zone, and the hydrogen cooling sintering ore zone in turn to react and obtain cold metallized sintered ore.

2. The method according to claim 1, characterized in that The introduced hydrogen-rich reducing gas passes through the hydrogen-cooled sintering zone, the electric induction-heated sintering zone and the hot-state sintering zone in sequence.

3. The method according to claim 1, characterized in that The raw materials and their mass percentages in step 1) include: 56.0-62.0% iron ore, 25-30% return ore, 7.0-12.0% flux, and 3.4-4.0% fuel.

4. The method according to claim 1, characterized in that: After hot sintered ore is crushed, screened and granulated, the particle size is controlled at 10-30mm and the temperature is above 800℃.

5. The method according to claim 1, characterized in that In the hot sintering belt, the high-temperature sintered ore above 800°C reacts with the reducing gas until the metallization rate of the sintered ore reaches above 45%, and the temperature is reduced to below 400°C and transmitted to the electric induction heating sintering belt; in the electric induction heating sintering belt, the sintered ore is heated by the electric induction coil, the temperature of the sintered ore is raised to above 800°C again, and then transmitted to the hydrogen cooling sintering belt; in the hydrogen cooling sintering belt, the sintered ore after magnetic induction heating continues to undergo reduction reaction with the reducing gas.

6. The method according to claim 5, characterized in that The medium frequency current is used to heat the sintered ore with high metallization rate through the induction coil. The power of the medium frequency power supply is 15000~25000kw.

7. The method according to claim 1, characterized in that The hydrogen-rich reducing gas is one or more of hydrogen, coke oven gas, and blast furnace gas, wherein the hydrogen content is above 35 vol%; the gas velocity of the hydrogen-rich reducing gas is 0.5-3.0 m / s.

8. The method according to claim 5, characterized in that The hydrogen content of the hydrogen-rich reducing gas in the hot sintering zone is more than 55 vol%; the hydrogen content in the electric induction heating sintering zone is more than 40 vol%; the hydrogen content in the hydrogen cooling sintering zone is more than 35 vol%.

9. The method according to claim 1, characterized in that: The tail gas generated by the electric induction heating hydrogen reduction system is returned to the hydrogen reduction system for circulation after being purified.

10. The cold metallized sintered ore prepared by the method according to any one of claims 1 to 9, characterized in that: The temperature of the cold metallized sintered ore is below 200°C and the metallization rate is above 55%.

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