System and method for producing metallized pellets based on plasma heating

Abstract

The application relates to the technical field of metallized pellets, and provides a system and a method for producing metallized pellets based on plasma heating, the system comprising a methane gas cabinet, a plasma exciter, a filtering chamber, a collecting chamber, a smoke hood, a reduction unit and a flue gas treatment station; the methane gas cabinet, the plasma exciter, the filtering chamber, the collecting chamber and the smoke hood are sequentially connected; high-temperature flue gas enters the reduction unit through the smoke hood to reduce the pellets. The method comprises the following steps: nitrogen replacement in a front gas replacement chamber; methane gas is sent into the reduction unit after plasma excitation; the pellets are reduced into metallized pellets; nitrogen replacement in a rear gas replacement chamber; flue gas recycling treatment and nitrogen and methane recycling. The method can obtain energy while treating methane, compared with a traditional gas-based shaft furnace, a large amount of external heating is reduced, and carbon emission can be reduced by more than 80%; meanwhile, the phenomenon of carbon deposition in the traditional reaction process is prevented, so that the furnace lining is protected, and the service life is prolonged.

Description

Technical Field

[0001] This invention relates to the field of metallized pellet technology, and in particular to a system and method for producing metallized pellets based on plasma heating. Background Technology

[0002] In 2022, China's crude steel output reached 1.017 billion tons, accounting for approximately 55.53% of the world's steel production capacity. China's steelmaking process is primarily based on a long process, requiring the extraction of iron from ore through blast furnaces. Many metallurgists and researchers have turned their attention to non-blast furnace ironmaking technologies to replace blast furnaces and achieve energy conservation and emission reduction goals.

[0003] Currently, mature non-blast furnace technologies can be divided into two categories: smelting reduction and direct reduction. Smelting reduction uses coal as raw material, reducing reliance on coke in the ironmaking process, thereby reducing energy consumption and emissions from coking. However, the development of smelting reduction technologies has been relatively slow, and its equipment performance and production efficiency are not stable enough to replace the blast furnace ironmaking process, and its application is limited worldwide. In contrast, direct reduction is more mature. Among them, gas-based direct reduction using hydrogen-rich gas as fuel is theoretically a zero-carbon emission ironmaking process. Currently, the most widely used gas-based direct reduction method in industrial applications is gas-based vertical shaft furnace direct reduction. Gas-based vertical shaft furnace direct reduction refers to a process that uses hydrogen-rich gases such as natural gas or coal gas at high temperatures to reduce ore pellets to produce metallized pellets. Gas-based vertical shaft furnace direct reduction also eliminates reliance on coke, and has a short process and low consumption of manpower and materials. However, current gas-based vertical shaft furnace production requires reforming of natural gas or coal gas, which consumes heat, and external heating is also required to obtain the temperature required for reduction. Therefore, the traditional gas-based vertical shaft furnace production process still inevitably generates a large amount of CO2 emissions.

[0004] A new ironmaking process needs to be developed to further reduce carbon emissions from the perspective of energy supply. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system and method for producing metallized pellets based on plasma heating. This system can release a large amount of energy while preparing reducing gas, thereby eliminating the energy consumption generated by external heating and achieving the ultimate goal of energy saving and emission reduction. The system has a simple structure and is easy to operate.

[0006] The present invention adopts the following technical solution:

[0007] On the one hand, the present invention provides a system for producing metallized pellets based on plasma heating, including a methane gas holder, a plasma exciter, a filter chamber, a collection chamber, a fume hood, a reduction unit, and a flue gas treatment station;

[0008] The reduction unit is used for the high-temperature reduction of pellets;

[0009] The methane gas holder, plasma exciter, filter chamber, and collection chamber are connected in sequence; methane gas is transported from the methane gas holder to the plasma exciter, and the high-temperature flue gas after plasma excitation is transported to the filter chamber for filtration, and then transported to the collection chamber.

[0010] One or more fume hoods are disposed above the reduction unit; the fume hoods are connected to the collection chamber; high-temperature flue gas enters the reduction unit through the fume hoods to reduce the pellets inside the reduction unit.

[0011] In addition to any of the possible implementations described above, a further implementation is provided in which the system further includes a front ventilation chamber and a rear ventilation chamber, wherein the front ventilation chamber, the reduction unit, and the rear ventilation chamber are sequentially and sealed together.

[0012] Both the front and rear ventilation chambers are equipped with front and rear doors, which are used for the input and output of pellets, respectively.

[0013] The tops of the front and rear air exchange chambers are connected to the nitrogen holder via pipes, and the bottoms are connected to the flue gas treatment station via pipes.

[0014] The reduction unit is provided with a flue below its tail end, and the flue is connected to the flue gas treatment station.

[0015] The nitrogen and methane, after being separated and purified by the flue gas treatment station, are transported back to the nitrogen holder and methane holder respectively through pipelines.

[0016] In addition to any of the possible implementations described above, another implementation is provided in which a flue gas analyzer is installed at the bottom of both the front and rear ventilation chambers.

[0017] In addition to any of the possible implementations described above, a further implementation is provided in which the filter chamber is composed of multiple layers of 400-mesh filter screens arranged in an alternating vertical structure; and a storage chamber for storing carbon powder is provided at the bottom of the filter chamber.

[0018] In addition to any of the possible implementations described above, another implementation is provided in which each of the filter layers is provided with a vibrator for shaking off carbon powder.

[0019] On the other hand, the present invention also provides a method for producing metallized pellets based on plasma heating, the method using the above-described system, the method comprising:

[0020] S1. The pellets enter the pre-ventilation chamber and undergo nitrogen replacement in the pre-ventilation chamber. When the replacement is completed, the oxygen concentration is less than the set threshold.

[0021] S2. Methane gas is transported from the methane gas holder to the plasma exciter. The high-temperature flue gas after plasma excitation is transported to the filter chamber for filtration, then to the collection chamber, and then evenly enters the reduction unit through one or more fume hoods.

[0022] S3. The pellets enter the reduction unit and undergo a reduction reaction with the high-temperature flue gas to obtain metallized pellets.

[0023] S4. The metallized pellets processed in step S3 enter the post-exchange chamber and undergo nitrogen replacement in the post-exchange chamber. After the replacement is completed, the finished metallized pellets are obtained.

[0024] The flue gas in S5, the front air exchange chamber, the reduction unit and the rear air exchange chamber are respectively recovered to the flue gas recovery station. After treatment and purification, nitrogen and methane are respectively transported back to the nitrogen tank and the methane tank for recycling through pipelines.

[0025] In addition to any of the possible implementations described above, another implementation is provided in which, in step S2, the hydrogen content in the high-temperature flue gas is controlled by controlling the parameters of the plasma exciter; after plasma excitation, the temperature of the high-temperature flue gas is 1400±50℃, and the composition of the high-temperature flue gas is 60% hydrogen, 25% methane, 15% other hydrocarbons, and carbon powder in solid form.

[0026] In addition to any of the possible implementations described above, a further implementation is provided in which, in step S2, the amount of solid toner is reduced by 90% after filtration through the filter chamber.

[0027] In addition to any of the possible implementations described above, another implementation is provided in which, in step S3, the time for the pellets to run on the trolley of the reduction unit is 30±2 minutes, and the metallization rate is not less than 95% when the pellets reach the end of the reduction unit.

[0028] In addition to any of the possible implementations described above, another implementation is provided in which the amount of filtered carbon powder is controlled at around 50 kg per ton of pellet ore.

[0029] In addition to any of the possible implementations described above, another implementation is provided in which, in step S1, when the pellet filling amount reaches 60% of the volume of the front ventilation chamber, the front and rear doors of the front ventilation chamber are closed for nitrogen purging; and in step S4, when the pellet filling amount reaches 90% of the volume of the front ventilation chamber, the front and rear doors of the rear ventilation chamber are closed for nitrogen purging.

[0030] The beneficial effects of this invention are as follows: The method of this invention obtains energy while processing methane, significantly reducing external heating compared to traditional gas-based vertical shaft furnaces, and lowering carbon emissions by over 80%. Through the selection and control of the working atmosphere and its synergistic effect with plasma, CO2 production during the reaction process is reduced. Simultaneously, it prevents carbon buildup seen in traditional reaction processes, thus protecting the furnace lining and extending its service life. From the perspective of heat acquisition, plasma heating is essentially electric heating; with the future development of green electricity technologies, the carbon emissions from energy supply using the method of this invention can approach zero. Attached Figure Description

[0031] Figure 1 The diagram shown is a structural schematic of a system for producing metallized pellets based on plasma heating according to an embodiment of the present invention.

[0032] Figure 2 The diagram shown is a schematic flow chart of a method for producing metallized pellets based on plasma heating according to an embodiment of the present invention.

[0033] In the diagram: 1-Reduction unit; 2-Front air exchange chamber; 3-Rear air exchange chamber; 4-Methane gas holder; 5-Plasma exciter; 6-Filter chamber; 7-Pipeline 1; 8-Collection chamber; 9-Storage chamber; 10-Pipeline 2; 11-Pipeline 3; 12-Flue gas analyzer 1; 13-Flue gas treatment station; 14-Flue gas analyzer 2; 15-Pipeline 4; 16-Pipeline 5; 17-Nitrogen holder; 18-Pipeline 6; 19-Pipeline 7; 20-Exhaust duct; 21-Pipeline 8; 22-Pipeline 9; 23-Hood 1; 24-Hood 2; 25-Hood 3; 26-Hood 4; 27-Pipeline 10. Detailed Implementation

[0034] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered in isolation, but can be combined with each other to achieve better technical effects.

[0035] Plasma heating refers to the process where, when a working gas is ionized into plasma, free electrons in the plasma recombine with positive ions, releasing energy to obtain a high-temperature working gas for reaction. This process can be described as follows: electrons in the working gas molecules form high-energy electrons under the influence of an electric field; these high-energy electrons interact with molecules to generate excited ions, molecules, and free radicals; atoms, molecules, and free radicals react with each other to form reaction products and heat of reaction. After plasma heating of the working gas, an activated working gas is obtained, which, at high temperatures, undergoes the breaking of chemical bonds to form new substances. For example, CH4 can be plasma-heated to produce high-temperature CH4, H2, C2H2, C2H4, C2H6, and C, etc. The hydrogen content can be controlled by adjusting the parameters of the plasma exciter (voltage, current, power, etc.). Increasing the current (or voltage, power, etc.) allows more electrons to gain energy and form high-energy electrons, thereby promoting the ionization process of hydrocarbons (C). n H m +e→C n H m-1 +H + ).

[0036] In this embodiment of the invention, methane is selected as the working gas. Its ionization process can replace traditional gas reforming, avoiding the catalysts and external heating required in traditional gas processing. The high-temperature working gas obtained through the ionization process contains a large amount of hydrogen, which reacts with the ore pellets in the reduction section to obtain metallized pellets with a metallization rate exceeding 95%. Through the reasonable design of the device, the flue gas circulation is controlled, thereby reducing environmental pollution.

[0037] like Figure 1 As shown, an embodiment of the present invention provides a system for producing metallized pellets based on plasma heating, comprising a methane gas holder 4, a plasma exciter 5, a filter chamber 6, a collection chamber 8, a fume hood (23-26), a reduction unit 1, and a flue gas treatment station 13;

[0038] The reduction unit 1 is used for the high-temperature reduction of pellets;

[0039] The methane gas holder 4, plasma exciter 5, filter chamber 6, and collection chamber 8 are connected in sequence; methane gas is transported from the methane gas holder 4 to the plasma exciter 5, and the high-temperature flue gas after plasma excitation is transported to the filter chamber 6 for filtration, and then transported to the collection chamber 8.

[0040] One or more smoke hoods (23-26) are arranged above the reduction unit 1; the smoke hoods (23-26) are connected to the collection chamber 8; high-temperature flue gas enters the reduction unit 1 through the smoke hoods (23-26) to reduce the pellets in the reduction unit 1.

[0041] Preferably, the fume hood is equipped with multiple 23-26 units, which is beneficial for the uniform distribution of high-temperature flue gas and the reduction unit.

[0042] In one specific embodiment, the reduction unit 1 is a closed trolley on which the pellets are transported.

[0043] In one specific embodiment, the system further includes a front ventilation chamber 2 and a rear ventilation chamber 3, wherein the front ventilation chamber 2, the reduction unit 1, and the rear ventilation chamber 3 are sequentially and sealed together; the front ventilation chamber 2 and the rear ventilation chamber 3 are used to purify air and flue gas, respectively.

[0044] Both the front ventilation chamber 2 and the rear ventilation chamber 3 are equipped with a front chamber door and a rear chamber door, which are used for the input and output of the pellets, respectively.

[0045] The tops of the front ventilation chamber 2 and the rear ventilation chamber 3 are connected to the nitrogen cabinet via pipes 19 and 15, respectively, and the bottoms are connected to the flue gas treatment station 13 via pipes 27 and 21, respectively.

[0046] The exhaust duct 20 is provided below the tail of the reduction unit 1, and the exhaust duct 20 is connected to the flue gas treatment station 13 through a pipe 21.

[0047] The nitrogen and methane separated and purified by the flue gas treatment station 13 are transported back to the nitrogen tank and methane tank through pipelines 18 and 22, respectively.

[0048] In one specific embodiment, flue gas analyzers 14 and 12 are installed at the bottom of both the front ventilation chamber 2 and the rear ventilation chamber 3.

[0049] In one specific embodiment, the filter chamber 6 is composed of multiple layers (e.g., 20 layers) of 400-mesh filter screens, which are arranged in an alternating vertical structure; a storage chamber 9 for storing carbon powder is provided at the bottom of the filter chamber 6.

[0050] In one specific embodiment, each of the filter screens is equipped with a vibrator for shaking off carbon powder. During the period when the ionization working gas is paused, the filter screen is vibrated by the vibrator at regular intervals to shake off the carbon powder. At this time, the door panel above the storage chamber 9 opens to allow the carbon powder to smoothly enter the storage chamber 9 for collection and storage, and then the door panel is closed.

[0051] like Figure 2 As shown, an embodiment of the present invention provides a method for producing metallized pellets based on plasma heating, using the above-described system. The method includes:

[0052] S1. The pellets enter the pre-air exchange chamber 2 and undergo nitrogen replacement in the pre-air exchange chamber 2. When the replacement is completed, the oxygen concentration is less than the set threshold (purified air).

[0053] S2. Methane gas is transported from methane gas holder 4 to plasma exciter 5. After plasma excitation, the high-temperature flue gas is transported to filter chamber 6 for filtration, then to collection chamber 8, and then uniformly enters reduction unit 1 through one or more fume hoods 23-26.

[0054] S3. The pellets enter reduction unit 1 and undergo a reduction reaction with the high-temperature flue gas to obtain metallized pellets.

[0055] Within reduction unit 1, high-temperature flue gas interacts with the ore pellets, causing the pellets to transform into metallized pellets through the reduction effect of the high-temperature flue gas. Within reduction unit 1, methane and other hydrocarbon gases undergo a cracking process at high temperatures (C2). n H m =nC + 0.5mH2);

[0056] Besides metallized pellets, the products of the interaction between high-temperature flue gas and pellets also include water vapor. At high temperatures, water vapor reacts with carbon to form carbon monoxide and hydrogen: C + H₂O(g) = CO + H₂. Adsorbed carbon produced by the pyrolysis process adheres to the pellet surface. Besides participating in the reduction reaction, this adsorbed carbon also reacts with the hydrogen reduction product—water vapor—and is consumed. In summary, the pyrolysis process increases the hydrogen concentration in the flue gas; the excess adsorbed carbon adhering to the pellets is promptly consumed, preventing it from covering the pellet surface and clogging the pores, allowing hydrogen to diffuse smoothly into the pellets. Ultimately, the pellet reduction process proceeds efficiently. Under the combined effect of a high hydrogen concentration and an appropriate amount of adsorbed carbon, the metallization rate of the pellets can be controlled by adjusting the trolley's running speed.

[0057] S4. The metallized pellets processed in step S3 enter the post-exchange chamber 3 and undergo nitrogen replacement (purification of flue gas) in the post-exchange chamber 3. After the replacement is completed, the finished metallized pellets are obtained.

[0058] S5, the flue gas in the front air exchange chamber 2, the reduction unit 1 and the rear air exchange chamber 3 are respectively recovered to the flue gas recovery station 13. After processing and purification, nitrogen and methane are respectively transported back to the nitrogen tank 17 and the methane tank 4 through pipelines 18 and 22 for recycling.

[0059] In one specific embodiment, in step S2, the hydrogen content in the high-temperature flue gas is controlled by adjusting the parameters of the plasma exciter 5. After plasma excitation, the temperature of the high-temperature flue gas is 1400±50℃, and the gas composition of the high-temperature flue gas is 60% hydrogen, 25% methane, and 15% other hydrocarbons. The flue gas also contains carbon powder in solid form. As mentioned earlier, the composition of the high-temperature flue gas can be controlled by adjusting the parameters of the plasma exciter. To achieve the purpose of this invention, the voltage of the plasma exciter is controlled at 20~30V, and the current at 150~200A. At this time, the carbon powder can reach the nanoscale, is extremely lightweight, and disperses in the flue gas in the form of carbon nanotubes, graphite carbon, etc., under the action of gas flow. If excessive carbon powder adheres to the pellets, it will hinder the reduction process of the material, while a small amount of carbon will help the reduction of the pellets. Therefore, flue gas treatment is required to remove excessive carbon powder (the amount of filtered carbon powder is controlled at about 50kg per ton of pellets), thereby improving the productivity of this invention.

[0060] In one specific embodiment, in step S2, the carbon powder formed by ionization has high activity and is easy to adhere to the filter screen. After the original high-temperature flue gas containing a large amount of carbon powder is filtered by the filter chamber 6, the amount of carbon powder in solid form is reduced by 90%.

[0061] In one specific embodiment, the purified high-temperature flue gas continues to flow forward along the pipeline 7 and is redistributed within the collection chamber 8. By adjusting the fan speed under the collection chamber 8, the flue gas flow rate through fume hoods 1-23 to 4-26 is controlled to be 5L / min, thereby uniformly delivering the high-temperature flue gas to the reduction unit 1.

[0062] In one specific embodiment, in step S1, when the pellet loading reaches 60% of the volume of the front ventilation chamber 2, the front and rear doors of the front ventilation chamber 2 are closed, and nitrogen replacement is performed to purify the air. Ensuring the front and rear doors are closed, nitrogen output from the nitrogen cabinet 17 is then introduced into the front ventilation chamber 2 via pipe 19, and the replaced gas is transported to the flue gas treatment station 13 via pipe 27. The completion of the replacement process is determined by the oxygen concentration in the flue gas analyzer 14 located below the front ventilation chamber 2. The entire ventilation process takes approximately 5 minutes. Immediately afterward, the rear door of the front ventilation chamber 2 is opened, and the pellets are fed into the reduction unit 1 via a sealed pipe connecting the reduction unit 1 and the front ventilation chamber 2. After the pellet reduction is completed, the pellets are sent into the rear ventilation chamber 3 via a sealed pipe between the reduction unit 1 and the rear ventilation chamber 3 as the trolley moves. At this time, the front door of the rear ventilation chamber 3 is opened. When the total amount of pellets reaches 90% of the volume of the rear ventilation chamber 3, the front chamber door is closed. At this point, the flue gas content in the rear ventilation chamber 3 is relatively low, which is beneficial for flue gas treatment. Nitrogen enters the rear ventilation chamber 3 through pipeline 15, and the flue gas analyzer 12 located below the rear ventilation chamber 3 determines whether the replacement is complete. The replaced gas is sent to the flue gas treatment station 13 through pipeline 16 for flue gas purification. Subsequently, the rear chamber door of the rear ventilation chamber 3 is opened, and the pellets are transported by a belt conveyor to the electric furnace or raw material silo for storage. It is worth mentioning that during the ventilation operation, the trolley in the reduction unit 1 is in a stopped state, but due to the favorable reduction conditions, the reduction process continues efficiently.

[0063] In one specific embodiment, in step S3, the time for the pellets to run on the trolley of the reduction unit is 30±2 minutes, and the metallization rate is not less than 95% when the pellets reach the end of the reduction unit.

[0064] In addition to the flue gas transported through pipes 16 and 27, the flue gas entering the flue gas treatment station 13 also includes flue gas from below the tail end of reduction unit 1 via exhaust duct 21. The purpose of setting up exhaust duct 21 below reduction unit 1 to discharge flue gas is to balance the pressure and temperature within reduction unit 1. Reduction unit 1 can actually form a self-circulation mechanism: ionization products ① CH4 and ② other hydrocarbons are decomposed into hydrogen and carbon at high temperatures. The water vapor generated from the ionization and decomposition products reacts with carbon to produce carbon monoxide and hydrogen. The carbon dioxide generated from the reduction of the carbon monoxide pellets reacts with the ionization and decomposition products carbon to produce carbon monoxide. Most of the reactions involved in this self-circulation are endothermic, thus requiring energy replenishment. The energy replenishment method is the ionization of methane. The introduction of methane gas will increase the pressure within reduction unit 1. Although increasing the pressure helps the reduction process, it causes significant wear and tear on the equipment. In summary, it is necessary to appropriately discharge cold flue gas, and the aforementioned self-circulation process will increase the CO concentration. Discharging cold flue gas also helps maintain the hydrogen concentration within reduction unit 1. The flue gas at the bottom of reduction unit 1 is in a relatively stable state. Since the molecular mass of other gases in reduction unit 1 is smaller than that of CO, CO is more distributed at the bottom of reduction unit 1. Therefore, placing the exhaust duct 21 at the bottom of reduction unit 1 is beneficial to improving CO discharge efficiency.

[0065] Inside the flue gas treatment station 13, flue gas is treated according to the different properties of various gases. The purified nitrogen and methane are sent to nitrogen tank 17 and methane tank 4 through pipelines 18 and 22 respectively, to continue to participate in the production of metallized pellets.

[0066] The method employed in this invention generates energy while processing methane. Compared to traditional gas-based vertical shaft furnaces, the energy consumption required to achieve the same reducing gas composition and temperature is only about one-quarter of that of fossil fuels, and carbon emissions can be reduced by more than 80%. Through the selection and control of the working atmosphere and its synergistic effect with plasma, CO2 production during the reaction process is reduced. Simultaneously, it prevents carbon buildup seen in traditional reaction processes, thus protecting the furnace lining and extending its service life. From a heat acquisition perspective, plasma heating is essentially electric heating; with the future development of green electricity technologies, the carbon emissions from energy supply using the method employed in this invention can approach zero.

[0067] While several embodiments of the present invention have been provided herein, those skilled in the art should understand that modifications can be made to these embodiments without departing from the spirit of the invention. The above embodiments are merely exemplary and should not be construed as limiting the scope of the invention.

Claims

1. A method for producing metallized pellets based on plasma heating, characterized in that, The method uses a system for producing metallized pellets based on plasma heating, the system including a methane gas holder, a plasma exciter, a filter chamber, a collection chamber, a fume hood, a reduction unit and a flue gas treatment station, as well as a pre-exchange chamber and a post-exchange chamber. The methane gas holder, plasma exciter, filter chamber, and collection chamber are connected in sequence. The fume hood is positioned above the reduction unit; The fume hood is connected to the collection chamber; The method includes: S1. The pellets enter the pre-exchange chamber and undergo nitrogen replacement in the pre-exchange chamber. When the replacement is completed, the oxygen concentration is less than the set threshold. S2. Methane gas is transported from the methane gas holder to the plasma exciter. The high-temperature flue gas after plasma excitation is then transported to the filter chamber for filtration, and then to the collection chamber. Finally, it is evenly introduced into the reduction unit through one or more fume hoods. The temperature of the high-temperature flue gas after plasma excitation is 1400±50℃. After the high-temperature flue gas is filtered through the filtration chamber, the amount of solid carbon powder is reduced by 90%. S3. The pellets enter the reduction unit and undergo a reduction reaction with the high-temperature flue gas to obtain metallized pellets. S4. The metallized pellets processed in step S3 enter the post-exchange chamber and undergo nitrogen replacement in the post-exchange chamber. After the replacement is completed, the finished metallized pellets are obtained. The flue gas in S5, the front air exchange chamber, the reduction unit and the rear air exchange chamber are respectively recovered to the flue gas recovery station. After treatment and purification, nitrogen and methane are respectively transported back to the nitrogen tank and the methane tank for recycling through pipelines.

2. The method for producing metallized pellets based on plasma heating as described in claim 1, characterized in that, In step S2, the hydrogen content in the high-temperature flue gas is controlled by controlling the parameters of the plasma exciter; after plasma excitation, the composition of the high-temperature flue gas is 60% hydrogen, 25% methane, and 15% other hydrocarbons.

3. The method for producing metallized pellets based on plasma heating as described in claim 1, characterized in that, In step S3, the pellets run on the trolley of the reduction unit for 30±2 minutes, and the metallization rate is not less than 95% when the pellets reach the end of the reduction unit.

4. The method for producing metallized pellets based on plasma heating as described in claim 1, characterized in that, In step S1, when the pellet filling amount reaches 60% of the volume of the front ventilation chamber, the front and rear doors of the front ventilation chamber are closed for nitrogen purging; in step S4, when the pellet filling amount reaches 90% of the volume of the front ventilation chamber, the front and rear doors of the rear ventilation chamber are closed for nitrogen purging.

5. The method for producing metallized pellets based on plasma heating as described in claim 1, characterized in that, The front ventilation chamber, the reduction unit, and the rear ventilation chamber are sequentially and sealed together. Both the front and rear ventilation chambers are equipped with front and rear doors, which are used for the input and output of pellets, respectively. The tops of the front and rear air exchange chambers are connected to the nitrogen holder via pipes, and the bottoms of the chambers are connected to the flue gas treatment station via pipes. The reduction unit is provided with a flue below its tail end, and the flue is connected to the flue gas treatment station.

6. The method for producing metallized pellets based on plasma heating as described in claim 5, characterized in that, Flue gas analyzers are installed at the bottom of both the front and rear ventilation chambers.

7. The method for producing metallized pellets based on plasma heating as described in claim 1, characterized in that, The filter chamber is composed of multiple layers of 400-mesh filter screens, which are arranged in an alternating vertical structure; a storage chamber for storing toner is provided at the bottom of the filter chamber.

8. The method for producing metallized pellets based on plasma heating as described in claim 7, characterized in that, Each of the filter layers is equipped with a vibrator to shake off toner.

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