Low-carbon ironmaking system and ironmaking method

Abstract

The invention belongs to the technical field of iron and steel smelting, and particularly relates to a low-carbon ironmaking system and an ironmaking method. The low-carbon ironmaking system comprises an iron ore powder feeding device, a reducing gas supply device, a fluidized bed device, an electric furnace feeding device and a melt separation electric furnace, the fluidized bed device comprises a fluidized bed feeding pipe, a fluidized bed discharging pipe, a fluidized bed gas inlet and a fluidized bed gas outlet, and the melt separation electric furnace comprises a furnace body, an electric furnace feeding pipe, an electrode device, a slag hole, an iron outlet and a coal gas outlet. The number of the electric furnace feeding pipes is two or more, and outlets of the electric furnace feeding pipes are all arranged in an electric arc area of an electrode of the electrode device. The iron ore powder feeding device is connected with the fluidized bed feeding pipe, the fluidized bed discharging pipe is connected with the electric furnace feeding pipe through the electric furnace feeding device, and the reducing gas feeding device is connected with a fluidized bed gas inlet. The method has the advantages that the reduced iron powder is directly smelted in the electric furnace, so that the briquetting process is omitted; hydrogen is adopted for reduction of iron ore powder, green electricity is adopted for a melting electric furnace, and CO2 emission in the ironmaking process is reduced by 80%.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel smelting technology, specifically relating to a low-carbon ironmaking system and ironmaking method. Background Technology

[0002] my country's steel industry still heavily relies on coal-based fossil fuels, resulting in significant carbon emissions, accounting for approximately 16% of the country's total carbon emissions. Therefore, effectively reducing carbon emissions during steel production has become a critical issue that urgently needs to be addressed by the steel industry and the nation as a whole.

[0003] The main process route from iron ore powder to crude steel is as follows: Route 1: Iron ore powder is first lumped (sintered ore and / or pellets), and then fed into a blast furnace. In the blast furnace, coke and pulverized coal are burned to smelt the sintered ore and / or pellets into molten iron, which is then sent to a converter or electric furnace to be smelted into crude steel.

[0004] Route 2: Iron ore powder is first made into pellets, and then the pellets are sent into a vertical shaft furnace. In the vertical shaft furnace, the pellets are reduced to sponge iron by reducing gas, and then the sponge iron is sent into an electric furnace to be smelted into crude steel.

[0005] Route 3: The iron ore powder is fed into a fluidized bed, where it is reduced to sponge iron powder by the heated reducing gas. The sponge iron powder is then pressed into block sponge iron, which is then fed into an electric furnace to be smelted into crude steel.

[0006] The disadvantages of the above three routes are: Route 1 is a typical long process, the main disadvantages of which are the long process, carbon metallurgy, and high CO2 emissions.

[0007] Route 2 is a short process and is currently the main solution for hydrogen metallurgy. Its disadvantages are: first, the vertical shaft furnace requires pellets, and the iron ore powder needs to be pelletized first; second, it has high requirements for the grade of iron ore powder, with an iron content of more than 67% and a gangue content of less than 3%.

[0008] Route 3 is a short process and represents the current research direction for hydrogen metallurgy. Its disadvantages include: firstly, sponge iron needs to be briquetteed before entering the electric furnace; secondly, it requires high-grade iron ore powder, with an iron content of over 66% and a gangue content of less than 3.5%; and thirdly, fluidized beds suffer from drawbacks such as "large heat diffusion losses during production, high power consumption of fluidized bed blasting, and easy agglomeration and loss of flow in the ore powder." Furthermore, current iron ore smelting primarily employs multi-stage series fluidized beds with complex and cumbersome structures. Due to the high hardness and density of iron ore, a multi-layer fluidized bed smelting scheme has not yet been developed.

[0009] Therefore, existing technologies urgently need a feasible low-carbon ironmaking method to meet the needs of low-carbon development. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides a low-carbon ironmaking system and method that can achieve low-carbon ironmaking in hydrogen metallurgy.

[0011] A low-carbon ironmaking system for producing molten iron from iron-containing materials using a fluidized bed reduction and electric furnace smelting process includes an iron ore powder feeding device, a reducing gas supply device, a fluidized bed device, an electric furnace feeding device, and a smelting electric furnace. The fluidized bed device includes a fluidized bed feed pipe, a fluidized bed discharge pipe, a fluidized bed air inlet, and a fluidized bed air outlet. The fluidized bed device is a multi-stage fluidized bed or a multi-layer fluidized bed. When the fluidized bed device is a multi-stage fluidized bed, at least one stage of the fluidized bed is a bubbling fluidized bed. When the fluidized bed device is a multi-layer fluidized bed, at least one fluidized bed layer is a bubbling bed layer, and the bubbling bed layer is a conical bed layer. The melting furnace includes a furnace body, a furnace feed pipe, an electrode device, a slag outlet, an iron tapping outlet, and a gas outlet. There are multiple furnace feed pipes, and the electrode device includes electrodes. The outlets of the furnace feed pipes are all located in the arc zone of the electrodes. The iron ore powder feeding device is connected to the fluidized bed feed pipe, the fluidized bed discharge pipe is connected to the electric furnace feed pipe through the electric furnace feeding device, and the reducing gas supply device is connected to the fluidized bed gas inlet.

[0012] This invention, by connecting the fluidized bed device and the smelting electric furnace using an electric furnace feeding device, with multiple electric furnace feed pipes and their outlets located in the arc zone of the electrodes, achieves multi-point, continuous distribution of iron ore powder near the electrodes. Compared to directly feeding the powder into the smelting electric furnace, this effectively reduces the thickness of the material layer inside the furnace, improves its permeability, and makes it possible for the smelting electric furnace to handle powdered iron. Based on this, the combination of the fluidized bed and the smelting electric furnace is achieved, resulting in the beneficial effects of low-carbon ironmaking.

[0013] The conical bed refers to a fluidized bed whose inner wall is not perpendicular to the horizontal plane, but forms a certain angle with the vertical line to the horizontal plane, called the cone angle. The cone angle of the conical bed is 1° to 45°. In the region where the fluidized material layer is located in the conical bed, the cross-section of the upper space is larger than the cross-section of the lower space, exhibiting a "larger at the top and smaller at the bottom" structure.

[0014] Since the mainstream coarse ore powder has a particle size distribution between 0-8mm, for coarse particles close to 8mm, bubbling fluidized bed is the most cost-effective choice, and large particles in coarse ore powder can be treated by bubbling fluidized bed.

[0015] The fluidized bed device of the present invention can be a multi-layer fluidized bed or a multi-stage fluidized bed. Depending on the actual engineering needs, the multi-stage fluidized bed may also include multiple multi-layer fluidized beds, or more than one multi-layer type bed, or a series or parallel connection of several multi-layer fluidized beds. The fluidized bed device may include a circulating fluidized bed, or a combination of a circulating fluidized bed and a bubbling fluidized bed. Preferably, the number of bed layers in the multi-layer fluidized bed is 2 to 9, more preferably 3 to 5, and the number of bed stages in the multi-stage fluidized bed is 2 to 9, more preferably 3 to 5.

[0016] Compared to multi-stage fluidized beds, multi-stage fluidized beds have drawbacks such as higher investment, larger footprint, higher energy consumption, and higher operating costs. However, in iron ore smelting processes, the wear problem of the air distribution plates in multi-stage fluidized beds is particularly severe. This is because iron ore, compared to ores such as zinc, copper, and nickel, has higher hardness and specific gravity. Therefore, if multi-stage fluidized beds are used for iron ore smelting, the high specific gravity of iron ore necessitates higher air velocities for fluidization. Higher air velocities easily blow fine particles from the iron ore to the air distribution plates, and the high hardness of iron ore leads to greater wear on the air distribution plates. This is a major technical challenge in using multi-stage fluidized beds for iron ore fluidization.

[0017] This invention addresses the wear problem in multi-layer fluidized bed iron ore smelting to a certain extent by setting up a conical bed, making multi-layer fluidized bed iron ore smelting possible. Because the conical bed, which is larger at the top and smaller at the bottom, creates a continuous distribution of air velocity in the empty tower, the fluidized particles can be stratified according to their diameter (smaller at the top and larger at the bottom). Furthermore, the supply and demand in the size direction are consistent, providing the operating air velocity according to the critical air velocity that allows various particle sizes to be fluidized. In other words, the setting of the conical bed can reduce the air velocity at the fine particles while ensuring that coarse particles can be fluidized, thus reducing the wear on the air distribution plate.

[0018] Furthermore, the gas outlet is connected to the outlet of the reducing gas supply device.

[0019] Furthermore, the electric furnace feeding device includes a reduced iron powder bin, a solvent bin, and a carbon powder bin, which are all connected to the electric furnace feed pipe via a weighing hopper and a chute, respectively.

[0020] The number of reduced iron powder chamber, solvent chamber and carbon powder chamber can be one, two or more. Preferably, the number of reduced iron powder chamber is two or more to better achieve multi-point material distribution.

[0021] The reduced iron powder silo is used to store iron ore powder after reduction by the fluidized bed device, the solvent silo is used to store the solvent used in the smelting process of the electric furnace, and the carbon powder silo is used to store the solvent used in the smelting process of the electric furnace.

[0022] Furthermore, the solvent tank includes a dolomite tank and a lime tank; Furthermore, the carbon powder silo is one or more of the following: coal powder silo, semi-coke silo, and coke silo.

[0023] Furthermore, the fluidized bed device is a multi-layer fluidized bed, which includes a gas distribution chamber located at the bottom, and the air inlet of the fluidized bed is located on the gas distribution chamber. The fluidized bed discharge pipe includes a lower discharge pipe, which is connected to the bottommost fluidized bed layer. The fluidized bed feed pipe and the fluidized bed air outlet are connected to the top fluidized bed layer; The fluidized bed layers are fed through a feed pipe; Each fluidized bed is equipped with an air distribution plate at the bottom.

[0024] Preferably, each layer of the multi-layer fluidized bed is a bubbling bed, that is, the multi-layer fluidized bed is a multi-layer bubbling fluidized bed; Preferably, each fluidized bed layer is equipped with an air supply pipe; Preferably, the top fluidized bed is a conical bed, and the fluidized bed discharge pipe further includes an upper discharge pipe. The inlet of the upper discharge pipe is located at the upper part of the top fluidized bed (Note: In this invention, the "bed" of a certain fluidized bed refers to the material layer within the fluidized bed), and the outlet of the upper discharge pipe is merged with the lower discharge pipe.

[0025] The advantages of this scheme are as follows: Due to the characteristics of the conical bed, under certain fluidization conditions, particles of different sizes are located at different heights in the bed. The top layer supports particles of all sizes. Fine particles and coarse particles require different reduction times and temperatures. Based on this, feed pipes or discharge pipes can be set at different heights in the bed. Fine particles, which are closer to the bed surface, react quickly, so an upper discharge pipe can be set and combined with a lower discharge pipe to lead the well-reacted fine particles out of the fluidized bed system. Coarse particles, which are more abundant in the lower part of the bed and react slowly, can be fed to the lower layer to continue reacting and finally discharged from the bottom discharge pipe. This can reduce energy consumption and further avoid wear on the air distribution plate. By removing fine particles from the multi-layer fluidized bed in a timely manner, the problem of adhesion and loss of flow caused by fine particles in the fluidized bed is also further avoided.

[0026] Furthermore, the feed pipe includes a bottom feed pipe and an overflow feed pipe, and the bottom feed pipe and the overflow feed pipe are installed in all fluidized bed layers except the bottom fluidized bed layer. The inlet of the bottom feed pipe is located at the air distribution plate of the fluidized bed, and the inlet of the overflow feed pipe is located at the height of the fluidized material surface to be controlled. The bottom feed pipe passes through the air distribution plate of the fluidized bed and enters the adjacent lower fluidized bed. A flow control valve is provided at the inlet of the bottom feed pipe. Alternatively, the bottom feed pipe first extends from the fluidized bed to the outside of the bed body, and then extends from the outside of the bed body into the adjacent lower fluidized bed. A flow control valve is provided on the pipe section of the bottom feed pipe outside the bed body.

[0027] Due to the characteristics of a conical bed, under certain fluidization conditions, particles of different sizes may be at different heights within the bed. Fine particles, mostly close to the bed surface, can be fed into the lower fluidized bed via the overflow pipe, thus maintaining the bed height at the design value. Coarser particles, mostly in the lower part of the bed, can be guided to the lower layer via the bottom feed pipe for further reaction, or ultimately discharged from the bottom fluidized bed. The bottom feed pipe is equipped with a control valve to regulate the feed rate and simultaneously adjust the proportion of coarse and fine particles in the bed, thereby adjusting the reaction time of the particles within the bed.

[0028] To facilitate the adjustment of bed heights and control of material reaction time, flow control valves can be installed on the feed pipe. However, due to the harsh working environment inside the fluidized bed, the control and lifespan of these valves are difficult to achieve the design goals. Therefore, a section of the pipe can be placed outside the fluidized bed, where flow control valves can be installed. This solves the problem and also facilitates the maintenance and replacement of the flow control valves.

[0029] Furthermore, in another embodiment of the present invention, the feeding pipe is a pneumatically controlled feeding device, which includes: a conveying pipe, a tray, a jet pipe, and an air inlet pipe. The conveying pipe vertically passes through the air distribution plate, with its upper opening (the feed inlet) in the upper layer of the adjacent fluidized bed and its lower opening (the discharge outlet) in the lower fluidized bed, generally in the space above the fluidized bed layer of the lower fluidized bed. The tray is positioned below the conveying pipe, arranged horizontally, and fixed to the air inlet pipe, the conveying pipe, or the fluidized bed shell. The air inlet pipe passes through the fluidized bed shell and is fixed to the shell, with its air inlet end connected sequentially to the air volume control device and the air source system outside the fluidized bed. The jet pipe is concentrically arranged inside the tray (i.e., the jet pipe and the tray are concentric), and the jet pipe wall has multiple air outlets, which are generally downward-facing to prevent material from entering. The air intake end of the jet pipe is connected to and fixed on the air intake pipe. Its air intake end is located in the center of the jet pipe and is a radial pipe that is part of the jet pipe, such as an "X" shaped pipe intersecting at the central air intake position.

[0030] Furthermore, the pneumatically controlled feeding device is equipped with a jet cone tower, which is a cone-shaped cavity with the tip pointing upwards. The cone wall has numerous air outlets or slits with an opening ratio of 1-40%. The air inlet pipe connects to the air inlet end of the jet pipe and also to the lower end of the jet cone tower, supplying it with air. The jet cone tower can also be independently supplied with air from a separate air source. The cone angle at the tip of the jet cone tower is 5-85°.

[0031] The working principle of the pneumatically controlled feeding device is as follows: Material enters the conveying pipe from the upper fluidized bed of an adjacent fluidized bed. After filling the tray at its outlet, the material cannot continue to fall and fill the conveying pipe due to the distance between the tray and the outlet of the conveying pipe being designed to meet the material's self-locking condition. When external controlled gas enters the jet pipe and the conical tower from the air inlet pipe and is ejected from the air holes of the jet pipe and the conical tower respectively, the ejected air can only flow out through the channel between the tray and the conveying pipe due to the constraint of the material column in the tray and the conveying pipe. This causes the material to fluidize and be thrown upwards and outwards. The cavity created by the material being thrown out of the tray prevents the material at the lower end of the conveying pipe from self-locking and causes it to flow downwards to fill the cavity. The filling material is continuously and repeatedly thrown out, and the material in the conveying pipe continues to flow downwards to replenish it. In this way, the material is conveyed from the upper bed to the lower bed. The larger the air volume entering through the air inlet pipe, the greater the flow rate of material thrown out per unit time. Therefore, we can control the flow rate of the material by controlling the air volume.

[0032] Furthermore, the jet pipe can be arranged in multiple concentric rings to meet the requirements of the pneumatic feeding device when the flow rate is high.

[0033] Furthermore, the inner and outer walls of the conveying pipe, the perimeter of the tray, and the outer wall of the air inlet pipe can all be covered with ceramic; the jet cone tower can be made of industrial ceramics.

[0034] The pneumatically controlled feeding devices of the above-mentioned inventions have the following advantages: First, based on the stable stratification of the conical bed, which allows for adjustable flow rates according to particle size, flow rate adjustment can allocate more of the reduction reaction space in the fluidized bed to coarse particles, improving the overall production efficiency of the fluidized bed and saving energy. Second, the appropriate spacing between the tray and the discharge port at the lower end of the conveying pipe creates a material self-locking condition smaller than the natural angle of repose, ensuring that the conveying pipe is always full of material within the set flow rate range, preventing short circuits between adjacent fluidized beds. Third, controlling the feeding flow rate by controlling the air intake is equivalent to a material flow regulating valve without any moving parts, making it both simple and reliable. Fourth, the structure of the invention ensures that material ejection does not wear down the tray or the lower end of the conveying pipe, solving the problem of the feeding device being difficult to use for extended periods in a fluidized bed.

[0035] Furthermore, a cyclone dust collector is provided inside or outside the top fluidized bed layer. The cyclone dust collector is connected to the air outlet of the fluidized bed, and the discharge port of the cyclone dust collector is connected to the top fluidized bed layer (injected into the top fluidized bed layer for circulating fluidization) and / or the lower discharge pipe (entering the next process).

[0036] Furthermore, the fluidized bed outlet of the fluidized bed device is sequentially connected to the outlets of the waste heat boiler I, the gas dust collector I, and the reducing gas supply device. A dehydration device and / or a CO2 removal device are also provided between the gas dust collector I and the reducing gas pressurization device. Furthermore, the gas outlet of the melting and separating electric furnace is sequentially connected to the outlets of the waste heat boiler II, the gas dust collector II, the gas compressor II, and the reducing gas supply device. Furthermore, the reducing gas supply device is sequentially connected to the reducing gas pressurization device, the reducing gas heating device, and the fluidized bed inlet of the fluidized bed device; The exhaust gas discharged from the fluidized bed outlet and the coal gas discharged from the coal gas outlet are treated and then combined with the reducing gas discharged from the reducing gas supply device. After being processed by the reducing gas pressurization device and the reducing gas heating device, they enter the fluidized bed from the fluidized bed inlet.

[0037] Furthermore, the iron ore powder feeding device includes an iron ore powder drying device, an iron ore powder silo, and a screw feeder connected in sequence, wherein the screw feeder is connected to the fluidized bed feed pipe; Furthermore, the melting furnace is a fully enclosed furnace structure; Furthermore, the electric furnace feed pipe of the melting furnace is also connected to the scrap steel bin; Furthermore, the furnace body of the melting and separating electric furnace is divided into an iron zone, a slag zone, and a furnace chamber zone from bottom to top. The furnace body is round or square, with an outer steel plate shell and an inner refractory material and cooling wall. The melting and separating electric furnace has multiple feed pipes, and the electrode device includes multiple electrodes. There are one or more furnace gas outlets. The tapping port is located in the lower part of the iron zone and is connected to the preheater. The outlet of the preheater is an iron trough, which has a dam. The dam is raised when tapping iron and falls down after tapping. The slag outlet is located on the side wall of the furnace body, in the lower part of the slag zone.

[0038] Furthermore, the gas supply device is one or a combination of two or more of the following: an electrolytic cell hydrogen production device, a biomass gas production device, a coal gas production device, a natural gas reforming device, and a coke oven gas reforming device.

[0039] The present invention also discloses a low-carbon ironmaking method using the above-mentioned low-carbon ironmaking system, comprising the following steps: Iron ore powder is fed into a fluidized bed device through an iron ore powder feeding device and a fluidized bed feed pipe. The iron ore powder undergoes a reduction reaction in the fluidized bed device, with a reduction degree of ≥70%. The material reduced by the fluidized bed device is transported to the melting and separation electric furnace through the fluidized bed discharge pipe and the electric furnace feeding device, where it continues to be reduced and melted into molten iron. The material after reduction by the fluidized bed device is fed into the melting furnace through multi-point feeding and continuous feeding, and nitrogen is used for sealing during the process.

[0040] Furthermore, the iron ore powder has a particle size ≤12mm.

[0041] Furthermore, the iron ore powder contains ≥50% iron. Due to the aforementioned technical improvements, this invention allows for the combined use of a fluidized bed apparatus and a smelting electric furnace for ironmaking. Because the smelting process removes gangue from low-grade ore, qualified molten iron is produced. Therefore, compared to a standalone fluidized bed apparatus, the low-carbon ironmaking system of this invention significantly reduces the requirement for the iron content of the iron ore powder.

[0042] Furthermore, the reducing gas in the fluidized bed device is hydrogen; the temperature of the reducing gas is ≥650℃; and the hydrogen is a gas with a hydrogen content of ≥90%.

[0043] Furthermore, the reducing gas in the fluidized bed device is a mixture of hydrogen and / or CO; the temperature of the reducing gas is ≥800℃; and the mixture of hydrogen and CO is a gas with a hydrogen and CO content of ≥90%.

[0044] Furthermore, the melting furnace uses green electricity; Furthermore, the reducing agent used in the smelting electric furnace is one or a combination of coal, semi-coke, and coke; Furthermore, the molten iron is used for steelmaking in a converter or electric furnace.

[0045] Compared with the prior art, the present invention has the following advantages: 1) The use of a multi-layer bubbling fluidized bed reduces heat diffusion loss during the production process and lowers the power consumption of the fluidized bed blower; 2) Reduced iron powder is directly fed into the melting and smelting electric furnace for smelting, eliminating the iron ore powder briquetting process; 3) The fully enclosed melting furnace ensures good production continuity, reduces heat loss, and is more environmentally friendly.

[0046] 4) When hydrogen is used for the reduction of iron ore powder and green electricity is used in the melting furnace, CO2 emissions from the ironmaking process are reduced by 80%. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the low-carbon ironmaking system in Example 1; Figure 2 This is a schematic diagram of the pneumatic feeding device provided in Example 3; Figure 3This is a top view of the pneumatic feeding device provided in Embodiment 3.

[0048] In the diagram: 1-Iron ore powder feeding device, 101-Iron ore powder drying device, 102-Iron ore powder silo, 103-Screw feeder, 201-Reducing gas supply device, 202-Reducing gas pressurization device, 203-Reducing gas heating device, 301-Multi-layer bubbling fluidized bed, 302-Fluidized bed outlet, 303-Built-in cyclone dust collector, 304-Feed pipe, 305-Upper discharge pipe, 306-Discharge pipe, 307-Bottom discharge pipe, 308-Lower discharge pipe, 309-Gas distribution chamber, 310-Air distribution plate, 401-Waste heat boiler I, 402-Gas dust collector I, 403-Dehydration device, 404-Adjustment... Pressure device, 501-reduced iron powder bin, 502-solvent bin, 503-carbon powder bin, 504-weighing hopper, 505-chute, 601-electric furnace, 602-electric furnace feed pipe, 603-electrode, 604-gas outlet, 605-slag zone, 606-molten iron zone, 607-tap, 608-preheater, 609-dam, 610-molten iron ditch, 611-slag outlet, 901-feeding pipe, 902-tray, 903-jet nozzle, 904-cone tower, 905-air inlet pipe, 906-gas flow control device, 907-gas source system, 908-cone tower outlet, 909-jet nozzle outlet. Detailed Implementation

[0049] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0050] Example 1: The following is an appendix Figure 1 For reference, the implementation of the present invention will be described in detail so that those skilled in the art can easily implement it. The present invention may be embodied in many different forms and is not limited thereto.

[0051] like Figure 1 As shown, this embodiment discloses a low-carbon ironmaking system, including an iron ore powder feeding device 1, a reducing gas supply device 201, a multi-layer bubbling fluidized bed 301, an electric furnace feeding device, and a melting electric furnace 601. The multi-layer bubbling fluidized bed 301 includes three fluidized bed layers, each of which is a conical bed layer. Each fluidized bed layer is provided with an air distribution plate 310 at the bottom. The top fluidized bed layer is provided with an upper discharge pipe 305, an overflow discharge pipe 306, and a bottom discharge pipe 307. The middle fluidized bed layer is provided with an overflow discharge pipe 306 and a bottom discharge pipe 307. The bottom fluidized bed layer is provided with a lower discharge pipe 308, and a gas distribution chamber 309 is provided below the bottom fluidized bed layer.

[0052] The fluidized bed air inlet is located on the air distribution chamber 309, the fluidized bed air outlet 302 is located on the top fluidized bed layer, the fluidized bed feed pipe 304 is located on the top fluidized bed layer, and the top fluidized bed layer is also equipped with a cyclone dust collector 303, the air outlet of the cyclone dust collector 303 is connected to the fluidized bed air outlet 302.

[0053] The melting electric furnace 601 includes a furnace body, an electric furnace feed pipe 602, and an electrode device. The electrode device includes an electrode 603 and a power supply device. The power supply device is connected to the electrode 603. The electrode 603 is inserted into the slag zone 605 from the top of the furnace body. In this embodiment, three electrodes 603 are provided. There is a gas outlet 604. The gas outlet 604 can be set on the side wall of the electric furnace 601 or on the furnace cover of the electric furnace 601.

[0054] In the smelting process of electric furnace 601, molten iron and slag are produced. The lower part of the furnace is the molten iron zone 606, and the upper part is the slag zone 605. Slag openings 611 are provided on the side walls of the furnace and at the bottom of the slag zone. After smelting, molten iron is discharged from the tapping port 607 of electric furnace 601 and the preheater 608, flowing into the ladle through the molten iron channel 610. A dam 609 is provided in the molten iron channel 610 at the outlet of the preheater 608. When tapping begins, the dam 609 is raised, and the molten iron flows into the ladle along the molten iron channel 610. After tapping is completed, the dam 609 is lowered. The height of the dam 609 is related to the amount of iron tapped. The amount of iron tapped each time is controlled by adjusting the height of the dam 609. The dam 609 is made of refractory material. A residual iron outlet is provided at the bottom or lower part of the smelting electric furnace 601. When it is necessary to empty the furnace, the residual iron outlet is opened to release the iron and slag inside the furnace.

[0055] The electric furnace feeding device includes a reduced iron powder bin 501, a carbon powder bin 502, and a solvent bin 503. The reduced iron powder bin 501, carbon powder bin 502, and solvent bin 503 are all connected to the electric furnace feed pipe 602 of the melting electric furnace 601 via a weighing hopper 504 and a chute 505. In this embodiment, three reduced iron powder bins 501 are provided (four, five, etc., can also be provided), each connected to a different electric furnace feed pipe 602 via its respective weighing hopper 504 and chute 505. The electric furnace feed pipes 602 are all located in the arc zone of the electrode 603. In this embodiment, the melting electric furnace 601 has six electric furnace feed pipes 602 (seven, eight, etc., can also be provided). (To clearly show the connection relationships...) Figure 1 Only one reducing iron powder bin 501 and four electric furnace feed pipes 602 are shown in the image.

[0056] The upper discharge pipe 305 and lower discharge pipe 308 of the multi-layer bubbling fluidized bed 301 are connected to the reduced iron powder silo 501, and the reduced iron powder silo 501 is equipped with a silo top dust collector.

[0057] The iron ore powder feeding device 1 includes an iron ore powder drying device 101, an iron ore powder silo 102, and a screw feeder 103 connected in sequence. The screw feeder 103 is connected to the fluidized bed feed pipe 304.

[0058] The fluidized bed outlet 302 is sequentially connected to the outlets of the waste heat boiler I 401, the gas dust collector I 402, the dehydration device 403, the pressure regulating device 404, and the reducing gas supply device 201. The gas outlet 604 is sequentially connected to the outlets of the waste heat boiler II (not shown in the figure), the gas dust collector II (not shown in the figure), the gas compressor II (not shown in the figure), and the reducing gas supply device 201. The reducing gas supply device 201 is sequentially connected to the reducing gas pressurizing device 202, the reducing gas heating device 203, and the fluidized bed inlet. The flue gas discharged from the fluidized bed outlet 302 and the gas discharged from the gas outlet 604 are purified and then combined with the reducing gas discharged from the reducing gas supply device 201. After being pressurized by the reducing gas pressurizing device 202 and heated by the reducing gas heating device 203, the gas enters the multi-layer bubbling fluidized bed 301 and is used as a reducing gas for recycling.

[0059] Example 2 This embodiment discloses a low-carbon ironmaking method, which uses the low-carbon ironmaking system of Embodiment 1.

[0060] In this embodiment, the iron ore powder to be reduced has a particle size of ≤12mm and an iron content of 55%.

[0061] The specific steps are as follows: Wet iron ore powder from the raw material yard is dried by iron ore powder drying device 101 and then sent to iron ore powder silo 102. The iron ore powder in iron ore powder silo 102 is quantitatively fed by screw feeder 103 with weighing function, and fed to the top fluidized bed layer of multi-layer bubbling fluidized bed 301 through fluidized bed feed pipe 304. The iron ore powder is reduced in the top fluidized bed layer. The reduced ultrafine particles (≤0.074mm) are discharged through the upper discharge pipe 305, and other particles are transported to the next fluidized bed layer through the discharge pipe (overflow discharge pipe 306, bottom discharge pipe 307) for reduction, and finally discharged from the bottom discharge pipe 308 of the bottom fluidized bed layer.

[0062] The reducing gas supply device 201 uses water electrolysis to produce hydrogen. The generated hydrogen is heated to 700°C by the reducing gas heating device 203 and then sent to the bottom gas distribution chamber 309 of the multi-layer bubbling fluidized bed 301. The hydrogen and iron ore powder heated in the multi-layer bubbling fluidized bed 301 react to generate reduced iron powder. In this embodiment, the metallization rate of the iron ore powder after reduction in the multi-layer bubbling fluidized bed 301 reaches about 70%. It is pneumatically conveyed (the conveying of reduced iron powder can also be done by a chain bucket elevator or a tank elevator) to the reduced iron powder silo 501 through the upper discharge pipe 305 and the lower discharge pipe 308.

[0063] After reduction, the exhaust gas from the multi-layer bubbling fluidized bed 301 enters the cyclone dust collector 303 for dust removal. The dust collected is returned to the top fluidized bed layer. The exhaust gas after dust removal is discharged from the fluidized bed outlet 302 at the top of the multi-layer bubbling fluidized bed 301 at a temperature ≥300℃. After heat recovery and cooling to ≤250℃ by the waste heat boiler I 401, it enters the gas dust collector I 402 for dust removal. The purified gas enters the dehydration device 403. Then, after pressure regulation by the pressure regulating device 404, the gas, together with hydrogen from the reducing gas supply device, enters the reducing gas pressurizing device 202 and is pressurized to ≥300kPa. Then, it enters the reducing gas heating device 203 and is heated to ≥700℃. The heated hydrogen is sent to the gas distribution chamber 309 of the multi-layer bubbling fluidized bed 301.

[0064] Reduced iron powder is loaded into electric furnace 601 via reduced iron powder silo 501, weighing hopper 504, chute 505, and electric furnace feed pipe 602. The reduced iron powder is fed into the furnace hot, with a temperature ≥500℃. Raw materials in solvent silo 502 and carbon powder silo 503 are metered by weighing hopper 504 and then loaded into electric furnace 601 via chute 505 and electric furnace feed pipe 602. The furnace charge is added near electrode 603. The reduced iron powder is fed using a multi-point, continuous feeding method. Nitrogen gas is used for sealing during the transportation, storage, and feeding of the reduced iron powder to prevent re-oxidation.

[0065] Green electricity is supplied to the melting furnace 601. After the electrode 603 is energized, it generates an electric arc to provide heat for the slag-iron melting and reduction reaction inside the furnace. The solvents (quicklime, dolomite, fluorite, etc.) added to the melting furnace 601 are used to prepare good slag, giving it good stability and desulfurization and dephosphorization efficiency. The added carbon powder reacts with the insufficiently reduced iron ore powder to produce iron and gas. The molten iron and slag produced by the reaction enter the molten iron layer 606 and the slag layer 605, respectively.

[0066] The coal gas produced by the smelting electric furnace 601 is discharged through the coal gas outlet 604. The exhaust gas temperature is ≥400℃. The heat is recovered by the waste heat boiler II. The low-temperature flue gas discharged from the waste heat boiler is purified by the coal gas dust collector II and pressurized by the coal gas compressor II before being sent to the outlet of the reducing gas supply device 201 for use as reducing gas.

[0067] Iron discharge: After smelting, the molten iron is discharged from the tapping port 607 of the electric furnace 601 and the preheating furnace 608, and flows into the ladle through the molten iron ditch 610. When tapping begins, the dam 609 is raised, and the molten iron flows into the ladle along the molten iron ditch 610. After tapping is completed, the dam 609 is lowered.

[0068] Slag discharge: Use a slag opening machine to open slag opening 611 and discharge the slag from the furnace. After water quenching, it becomes water slag. After the slag discharge is completed, use a mud gun to plug slag opening 611. The plugging material is refractory material.

[0069] In this embodiment, hydrogen is supplied to the fluidized bed to reduce the iron ore powder and to supply green electricity to the electric furnace. Therefore, the entire ironmaking process involves very little carbon (approximately 50 kg / t). 铁 It is used for further reduction of iron ore powder that has not been fully reduced in the melting electric furnace, thus greatly reducing CO2 emissions in the ironmaking process to only 20% of those in the long-process ironmaking process.

[0070] Example 3 The only difference between this embodiment and Embodiment 1 is that a pneumatically controlled feeding device is used for the feeding pipe, such as... Figures 2-3 As shown, the pneumatically controlled feeding device mainly consists of a conveying pipe 901, a tray 902, a jet pipe 903, an air inlet pipe 905, and a jet cone tower 904. The connection relationships and functions of each component are as follows: The conveying pipe 901 is arranged vertically, with its upper end connected to the upper fluidized bed and its lower end in the lower fluidized bed. It is used to receive the mineral powder discharged from the upper bed and guide the mineral powder vertically downward to the tray 902 below.

[0071] The tray 902 is horizontally positioned below the conveying pipe 901 to temporarily store the mineral powder falling from the discharge pipe. The tray 902 is fixedly connected to the air inlet pipe 905, thereby limiting the spatial position of the tray 902 and ensuring its structural stability during material transfer.

[0072] The jet pipe 903 and the air inlet pipe 905 are both located inside the tray 902. The jet pipe 903 has multiple air outlet holes 909 on its wall, which are generally downward-facing to prevent material from entering. The air inlet end of the jet pipe 903 is connected to and fixed to the air inlet pipe 905. The air inlet end is located at the center of the jet pipe 903 and is a radial pipe, like an "X" shaped pipe, intersecting at the central air inlet position. After the gas enters the jet pipe 903 through the air inlet pipe 905, it is evenly discharged from the air outlet holes 909 on the wall of the jet pipe 903, providing fluidization power for the mineral powder in the tray 902.

[0073] The jet cone tower 904 is a cone-shaped cavity with its tip pointing upwards. Numerous air outlet holes 908 are provided on the cone wall, with an opening ratio controlled between 2% and 20%. The air inlet pipe 905 connects to the air inlet end of the jet pipe 903 and also to the lower end of the jet cone tower 904, supplying it with air. The jet cone tower 904 can also be independently supplied with air from a separate air source. The cone angle at the tip of the jet cone tower 904 is within the range of 5° to 85°. This structure effectively breaks up the central column formed by the accumulation of mineral powder, assisting the fluidization process and avoiding a "central dead zone."

[0074] When the pneumatic feeding device of this embodiment is working, the mineral powder enters the tray 902 for temporary storage through the conveying pipe 901. The fluidizing gas forms a fluidized airflow through the air inlet pipe 905 and the air outlet 909 of the air jet pipe 903. With the assistance of the air jet cone tower 904, the mineral powder is kept in a fluidized state and uniformly transported downward. The flow rate of the mineral powder can be flexibly controlled by adjusting the air intake of the air inlet pipe, which solves the problems of narrow adjustment range, easy wear and poor uniformity of traditional feeding methods.

[0075] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical aspects of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A low-carbon ironmaking system, characterized in that, This includes an iron ore powder feeding device, a reducing gas supply device, a fluidized bed device, an electric furnace feeding device, and a melting electric furnace. The fluidized bed device includes a fluidized bed feed pipe, a fluidized bed discharge pipe, a fluidized bed air inlet, and a fluidized bed air outlet. The fluidized bed device is a multi-stage fluidized bed or a multi-layer fluidized bed. When the fluidized bed device is a multi-stage fluidized bed, at least one stage of the fluidized bed is a bubbling fluidized bed. When the fluidized bed device is a multi-layer fluidized bed, at least one fluidized bed layer is a bubbling bed layer, and the bubbling bed layer is a conical bed layer. The melting furnace includes a furnace body, a furnace feed pipe, an electrode device, a slag outlet, an iron tapping outlet, and a gas outlet. There are multiple furnace feed pipes, and the electrode device includes electrodes. The outlets of the furnace feed pipes are all located in the arc zone of the electrodes. The iron ore powder feeding device is connected to the fluidized bed feed pipe, the fluidized bed discharge pipe is connected to the electric furnace feed pipe through the electric furnace feeding device, and the reducing gas supply device is connected to the fluidized bed gas inlet.

2. The low-carbon ironmaking system according to claim 1, characterized in that, The gas outlet is connected to the outlet of the reducing gas supply device.

3. The low-carbon ironmaking system according to claim 1, characterized in that, The electric furnace feeding device includes a reduced iron powder bin, a solvent bin, and a carbon powder bin. There are two or more reduced iron powder bins. The reduced iron powder bin, solvent bin, and carbon powder bin are all connected to the electric furnace feed pipe through a weighing hopper and a chute, respectively.

4. The low-carbon ironmaking system according to claim 3, characterized in that, The solvent tank includes a dolomite tank and a lime tank; And / or, the carbon powder silo is one or more of the following: coal powder silo, semi-coke silo, and coke silo.

5. The low-carbon ironmaking system according to claim 1, characterized in that, The fluidized bed device is a multi-layer fluidized bed, which includes a gas distribution chamber at the bottom and an air inlet located on the gas distribution chamber. The fluidized bed discharge pipe includes a lower discharge pipe, which is connected to the bottommost fluidized bed layer. The fluidized bed feed pipe and the fluidized bed air outlet are connected to the top fluidized bed layer; The fluidized bed layers are fed through a feed pipe; Each fluidized bed is equipped with an air distribution plate at the bottom.

6. The low-carbon and zero-carbon ironmaking system according to claim 5, characterized in that, Each layer of the multi-layer fluidized bed is a bubbling bed, and / or each fluidized bed layer is equipped with a gas supply pipe.

7. The low-carbon and zero-carbon ironmaking system as described in claim 5, characterized in that, The top fluidized bed is a conical bed, and the fluidized bed discharge pipe also includes an upper discharge pipe. The inlet of the upper discharge pipe is located at the top of the top fluidized bed, and the outlet of the upper discharge pipe is merged with the lower discharge pipe.

8. The low-carbon ironmaking system according to claim 5 or 7, characterized in that, The feed pipe includes a bottom feed pipe and an overflow feed pipe, which are installed in all fluidized bed layers except the bottom fluidized bed layer. The inlet of the bottom feed pipe is located at the air distribution plate of the fluidized bed, and the inlet of the overflow feed pipe is located at the height of the fluidized material surface to be controlled. The bottom feed pipe passes through the air distribution plate of the fluidized bed and enters the adjacent lower fluidized bed. A flow control valve is provided at the inlet of the bottom feed pipe. Alternatively, the bottom feed pipe first extends from the fluidized bed to the outside of the bed body, and then extends from the outside of the bed body into the adjacent lower fluidized bed. A flow control valve is provided on the pipe section of the bottom feed pipe outside the bed body.

9. The low-carbon ironmaking system according to claim 5, characterized in that, The feeding pipe is a pneumatically controlled feeding device, which includes: a feeding pipe, a tray, a jet pipe, and an air inlet pipe; the feeding pipe passes vertically through the air distribution plate, and the tray is located below the feeding pipe; the jet pipe is located inside the tray, and its pipe wall is provided with multiple air outlets, and the jet pipe is connected to the air inlet pipe; the air inlet pipe passes through the fluidized bed shell and is fixed to the shell, and its air inlet end is connected to the gas flow control device and the gas source system in sequence outside the fluidized bed.

10. The low-carbon ironmaking system according to claim 9, characterized in that, The pneumatically controlled feeding device is equipped with a jet cone tower, which is a cone-shaped cavity with the tip pointing upwards. The cone wall is provided with many air outlets or air slits with an opening rate of 1~40%. The air inlet pipe is connected to the lower end of the jet cone tower to supply air, or the jet cone tower is supplied with air independently by another separate air source. The cone angle of the tip of the jet cone tower is 5~85°.

11. The low-carbon ironmaking system according to any one of claims 5 to 8, characterized in that, A cyclone dust collector is provided inside or outside the top fluidized bed layer. The cyclone dust collector is connected to the air outlet of the fluidized bed, and the discharge port of the cyclone dust collector is connected to the top fluidized bed layer and / or the lower discharge pipe.

12. The low-carbon ironmaking system according to claim 1, characterized in that, It also includes one or more of the following technical features: The fluidized bed outlet of the fluidized bed device is sequentially connected to the outlets of the waste heat boiler I, the gas dust collector I, and the reducing gas supply device. A dehydration device and / or a CO2 removal device are also provided between the gas dust collector I and the reducing gas pressurization device. The gas outlet of the melting and separating electric furnace is sequentially connected to the outlets of the waste heat boiler II, the gas dust collector II, the gas compressor II, and the reducing gas supply device. The reducing gas supply device is sequentially connected to the reducing gas pressurization device, the reducing gas heating device, and the fluidized bed inlet of the fluidized bed device. The reducing gas supply device is one or a combination of two or more of the following: an electrolytic cell hydrogen production device, a biomass gas production device, a coal gas production device, a natural gas reforming device, and a coke oven gas reforming device.

13. A low-carbon ironmaking system according to claim 1, characterized in that, It also includes one or more of the following technical features: The iron ore powder feeding device includes an iron ore powder drying device, an iron ore powder silo, and a screw feeder connected in sequence, and the screw feeder is connected to the fluidized bed feed pipe; The melting furnace is a fully enclosed furnace structure. The electric furnace feed pipe of the melting furnace is also connected to the scrap steel bin; The furnace body of the smelting electric furnace is divided into an iron zone, a slag zone, and a furnace chamber zone from bottom to top. The tap hole is located in the lower part of the iron zone and is connected to the pre-heater. The outlet of the pre-heater is an iron trough with a dam inside. The slag outlet is located on the side wall of the furnace body, in the lower part of the slag zone.

14. A low-carbon ironmaking method utilizing the low-carbon ironmaking system of claims 1-13, characterized in that, Includes the following steps: Iron ore powder is fed into a fluidized bed device through an iron ore powder feeding device and a fluidized bed feed pipe. The iron ore powder undergoes a reduction reaction in the fluidized bed device, with a reduction degree of ≥70%. The material reduced by the fluidized bed device is transported to the melting and separation electric furnace through the fluidized bed discharge pipe and the electric furnace feeding device, where it continues to be reduced and melted into molten iron. The material after reduction by the fluidized bed device is fed into the melting furnace through multi-point feeding and continuous feeding, and nitrogen is used for sealing during the process.

15. The low-carbon ironmaking method according to claim 14, characterized in that, The iron ore powder has a particle size of ≤12mm.

16. The low-carbon ironmaking method according to claim 14, characterized in that, The iron ore powder has an iron content of ≥50%.

17. The low-carbon ironmaking method according to claim 14, characterized in that, The reducing gas in the fluidized bed device is hydrogen; the temperature of the reducing gas is ≥650℃; and the hydrogen is a gas with a hydrogen content of ≥90%.

18. The low-carbon ironmaking method according to claim 14, characterized in that, The reducing gas in the fluidized bed device is a mixture of hydrogen and / or CO; the temperature of the reducing gas is ≥800℃; the mixture of hydrogen and CO is a gas with a hydrogen and CO content of ≥90%.

19. The low-carbon ironmaking method according to claim 14, characterized in that, It also includes one or more of the following technical features: The melting furnace uses green electricity; The reducing agent used in the smelting electric furnace is one or a combination of coal, semi-coke, and coke. The molten iron is used for steelmaking in converters or electric furnaces.

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