Gas flow cyclone direct reduction shaft furnace, system and method for direct smelting iron

Abstract

The present application relates to the technical field of steel metallurgy, and particularly relates to a gas flow cyclone type direct reduction shaft furnace, a system and a method for direct iron smelting by rotation and floating. The gas flow cyclone type direct reduction shaft furnace comprises a reduction furnace column cavity, a rotation and floating type nozzle arranged at the top of the reduction furnace column cavity, a reduction furnace cone cavity fixedly connected with the bottom of the reduction furnace column cavity, a mushroom arranged at the joint of the reduction furnace column cavity and the reduction furnace cone cavity, used for dispersing powder and then uniformly entering the reduction furnace cone cavity, a tail gas discharge port arranged at the bottom of the mushroom, a tail gas pipeline connected with the tail gas discharge port, and a lock hopper arranged at the bottom of the reduction furnace cone cavity. The gas flow cyclone type direct reduction shaft furnace is applied to the system for direct iron smelting by rotation and floating, which not only saves a large amount of fixed investment and occupies less area, but also provides an economic, reliable and efficient low-carbon path for industrial engineering and rapid iron making of medium and low grade iron ore.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to a system and method for a gas flow cyclone direct reduction vertical furnace and a cyclone-float direct ironmaking process. Background Technology

[0002] Blast furnace-converter metallurgy accounts for over 70% of global production, with China accounting for 51% of global steel production, and blast furnace-converter processes dominating, accounting for over 90%. Blast furnace ironmaking consumes vast amounts of energy and generates significant amounts of carbon dioxide. Therefore, facing the requirements of green, low-carbon steelmaking and carbon dioxide emission reduction, a key issue for the steel industry is developing a more energy-efficient and environmentally friendly innovative ironmaking technology. Simultaneously, the new ironmaking technology should be significantly cheaper than the blast furnace / coke oven combination and must be able to produce iron at a sufficiently high rate to supply raw materials to steel mills. Currently, the solid feedstock in blast furnace processes mainly consists of iron ore sinter or pellets and coke made from coking coal; both production processes consume large amounts of energy and easily cause environmental pollution. Alternative direct reduction processes for ironmaking have seen significant development in recent years, with gas-solid and solid-solid direct reduction processes growing rapidly. Alongside the development of vertical shaft furnace processes, fluidized bed processes have also become the subject of investigation and experimentation. However, the intensity of these processes is insufficient to compete with blast furnaces. The vertical shaft furnace process requires the use of iron oxide concentrate pellets, but the global high-grade iron concentrate content is only 4%. To obtain high-quality pellets, reverse flotation is required during mining, followed by pellet processing, oxidized pellet roasting, and then reduction in a gas-based vertical shaft furnace. This process consumes additional energy and emits pollutants, including CO2. While fluidized bed blast furnaces eliminate the agglomeration process, they require a certain level of high-temperature resistant ore or coating of the ore powder to prevent scaling and adhesion during high-temperature reduction, which could disrupt production. In the early 21st century, inspired by flash copper, flash nickel, and flash lead smelting, research on flash ironmaking began both domestically and internationally. Experimental-led research found that in a reducing gas environment of 1750K and an excess coefficient of 500% H2+CO, iron ore could be reduced to 99% within 3 seconds, demonstrating the superior performance of flash ironmaking and paving the way for its industrialization as a replacement for blast furnace ironmaking. However, the progress of this process is slow due to the defects in equipment and technology itself. Its reduction furnace + melting is a violent oxidation coupled reaction with strong reduction in the upper part and combustion of hydrogen or natural gas in the lower part. The tail gas temperature is high, and it requires a complex and huge treatment system for power generation or purification. This not only increases the investment and safety hazards, but also results in low primary energy utilization. Summary of the Invention

[0003] In view of this, the technical problem to be solved by the present invention is to provide a system and method for direct reduction shaft furnace with airflow cyclone and direct ironmaking with cyclone flotation, which is economical, reliable and efficient.

[0004] This invention provides an airflow cyclone direct reduction vertical furnace, comprising:

[0005] A reduction furnace column cavity; a swirling nozzle is installed at the top of the reduction furnace column cavity;

[0006] A reduction furnace conical cavity is fixedly connected to the bottom of the reduction furnace cylindrical cavity; a mushroom cap is provided at the connection between the reduction furnace cylindrical cavity and the reduction furnace conical cavity to disperse the powder and allow it to enter the reduction furnace conical cavity evenly; a tail gas outlet is provided at the bottom of the mushroom cap;

[0007] An exhaust pipe connected to the exhaust outlet;

[0008] A locking hopper is provided at the bottom of the cone cavity of the reduction furnace.

[0009] Preferably, the swirling nozzle comprises:

[0010] An inverted cone-shaped cavity; a mineral powder inlet and a distribution air inlet are sequentially arranged at the top center of the cavity in a direction away from the cavity; two process air inlets are arranged at the top of the cavity near the edge, with the two process air inlets located on both sides of the top center;

[0011] An outlet is provided at the bottom of the cavity; an air regulating cone is provided at the outlet of the cavity; a ore separating cone is provided at the outlet of the air regulating cone; a distribution air device is provided at the bottom of the ore separating cone; a heat insulation plate is provided at the bottom of the distribution air device; the material powder entering from the ore powder inlet forms a material column under the action of the distribution air device, the ore separating cone and the air regulating cone and the material is discharged evenly.

[0012] The outlet of the cavity is connected to the top of the column cavity of the reduction furnace.

[0013] Preferably, the angle of the top of the mushroom cap does not exceed 70°.

[0014] The present invention also provides a system for direct ironmaking by swirl flotation, comprising:

[0015] Cyclone direct reduction vertical shaft furnace;

[0016] A waste heat boiler connected to the tail gas pipe of the aforementioned airflow cyclone direct reduction vertical furnace;

[0017] A cyclone dust collector connected to the gas outlet of the waste heat boiler;

[0018] A scrubbing tower connected to the gas outlet of the cyclone dust collector;

[0019] An absorption tower is connected to the gas outlet of the spraying tower; the gas outlet of the absorption tower is provided with two paths; the first path is connected to a heating furnace; the gas outlet of the heating furnace is connected to the process air inlet of the airflow cyclone direct reduction vertical furnace; the second path is connected to a feeding tank; the outlet of the feeding tank is connected to the ore powder inlet of the airflow cyclone direct reduction vertical furnace.

[0020] The top of the feeding tank is provided with a feeding port; the feeding port of the feeding tank is connected to the locking hopper; the top of the locking hopper is provided with a feeding port; the feeding port of the locking hopper is connected to the silo.

[0021] The gas flow cyclone direct reduction vertical furnace is the gas flow cyclone direct reduction vertical furnace described above.

[0022] The present invention also provides a method for direct ironmaking by swirl flotation, comprising the following steps:

[0023] S1) Iron ore powder is injected into a cyclone direct reduction vertical furnace through a swirling nozzle using a high-temperature reducing carrier gas of 850-1200℃. The powder rotates, floats, and descends, undergoing physicochemical reactions involving mass and heat transfer during its descent to obtain iron powder. The obtained iron powder is dispersed and guided by a funnel and enters the cone cavity of the reduction furnace before entering the lock hopper. The tail gas is discharged through the tail gas pipe.

[0024] S2) The exhaust gas obtained in step S1) is cooled by heat exchange in a waste heat boiler. The temperature of the exhaust gas after cooling is 270-290°C. After being humidified by water spraying, the temperature of the exhaust gas is further reduced to below 180°C.

[0025] S3) Remove dust from the gas processed in step S2);

[0026] S4) Spray the gas processed in step S3) to wash it;

[0027] S5) Remove carbon dioxide from the gas processed in step S4);

[0028] S6) After mixing and heating a portion of the gas processed in step S5) with fresh reducing gas, it is reused as the high-temperature reducing carrier gas in the gas flow cyclone direct reduction vertical furnace.

[0029] Another portion of the gas processed in step S5) is mixed with the carrier gas carrying iron ore powder and then reused for the iron ore powder in the gas flow cyclone direct reduction shaft furnace.

[0030] Preferably, in step S1), the iron ore powder is a medium-to-low grade iron ore powder; the iron content in the iron ore powder is 50% to 65% by mass.

[0031] The iron ore powder has a particle size of 200 mesh and a moisture content of less than 1%.

[0032] Preferably, in step S1), the components of the high-temperature reducing carrier gas include at least one of natural gas, syngas, and hydrogen.

[0033] Iron ore powder is reduced with carrier gas at a high temperature of 850–1200℃, with the gas-solid ratio controlled at 5–10 kg / Nm³. 3 .

[0034] Preferably, in step S1), the physicochemical reaction takes 3 to 5 seconds.

[0035] Preferably, the spraying solution used in the spraying is fresh industrial water;

[0036] The absorbent used for carbon dioxide removal includes MEDA, an active agent, and water; the active agent is selected from MEA, DEA, or PZ.

[0037] Preferably, in step S6), the volume ratio of one part of the gas to another part of the gas after the treatment in step S5) is 1.5 to 2.5:1;

[0038] A portion of the gas processed in step S5) is mixed with fresh reducing gas and heated to a temperature of 850–1200°C.

[0039] The volume ratio of a portion of the gas processed in step S5) to fresh reducing gas is 1.5 to 2.5:1.

[0040] In step S5), the volume ratio of the other part of the gas after treatment to the carrier gas carrying iron ore powder is 1.5 to 2.5:1.

[0041] The carrier gas is selected from at least one of nitrogen and carbon dioxide.

[0042] This invention flexibly employs a vortex-type nozzle, high-temperature reducing gas as a carrier, a mushroom-type finished product collection system, and a lock hopper-type finished product collection system to ensure the smooth operation and reliability of the process. Applying this invention's airflow cyclone direct reduction shaft furnace to a vortex-type direct ironmaking system eliminates the need for supporting coking, sintering, pelletizing, and flux plants. This not only saves significant fixed investment and reduces land area requirements, but also provides an economical, reliable, efficient, and low-carbon pathway for the rapid ironmaking of medium- and low-grade iron ore in industrial engineering. Attached Figure Description

[0043] Figure 1 A structural diagram of a gas flow cyclone direct reduction vertical furnace provided for one embodiment of the present invention;

[0044] Figure 2 A system diagram of a vortex-flotation direct ironmaking process provided for one embodiment of the present invention. Detailed Implementation

[0045] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0046] This invention provides an airflow cyclone direct reduction vertical furnace, comprising:

[0047] A reduction furnace column cavity; a swirling nozzle is installed at the top of the reduction furnace column cavity;

[0048] A reduction furnace conical cavity is fixedly connected to the bottom of the reduction furnace cylindrical cavity; a mushroom cap is provided at the connection between the reduction furnace cylindrical cavity and the reduction furnace conical cavity to disperse the powder and allow it to enter the reduction furnace conical cavity evenly; a tail gas outlet is provided at the bottom of the mushroom cap;

[0049] An exhaust pipe connected to the exhaust outlet;

[0050] A locking hopper is provided at the bottom of the cone cavity of the reduction furnace.

[0051] Figure 1 This is a structural diagram of a gas flow cyclone direct reduction vertical furnace provided as an embodiment of the present invention.

[0052] Among them, 1-1-1 is the column cavity of the reduction furnace, 1-1-2 is the cone cavity of the reduction furnace, 1-2 is the swirling nozzle, 1-3 is the locking hopper, 1-4 is the mushroom cap, 1-5 is the tail gas pipe, 1-6 is the heat insulation plate, 1-7 is the distribution air device, 1-8 is the ore separating cone, 1-9 is the air regulating cone, 1-10 is the process air inlet (high temperature reduction carrier gas inlet or high reduction potential gas inlet), 1-11 is the ore powder inlet, 1-12 is the distribution air inlet, 1-13 is the inverted cone-shaped cavity, and 1-14 is the material column.

[0053] In some embodiments of the present invention, the swirling nozzles 1-2 can be vortex column spray guns, with specific structures as follows: Figure 1 As shown, it includes:

[0054] An inverted cone-shaped cavity; a mineral powder inlet and a distribution air inlet are sequentially arranged at the top center of the cavity in a direction away from the cavity; two process air inlets are arranged at the top of the cavity near the edge, with the two process air inlets located on both sides of the top center;

[0055] An outlet is provided at the bottom of the cavity; an air regulating cone is provided at the outlet of the cavity; a ore separating cone is provided at the outlet of the air regulating cone; a distribution air device is provided at the bottom of the ore separating cone; a heat insulation plate is provided at the bottom of the distribution air device; the material powder entering from the ore powder inlet forms a material column under the action of the distribution air device, the ore separating cone and the air regulating cone and the material is discharged evenly.

[0056] The outlet of the cavity is connected to the top of the column cavity of the reduction furnace.

[0057] The present invention does not impose any particular limitation on the material of the inverted conical cavity; it can be Q235 carbon structural steel or 310 heat-resistant stainless steel. Alternatively, the cavity material may also include a steel substrate and a protective layer formed on the steel substrate; the protective layer may be a refractory material or a corundum ceramic sheet with rivets; the steel substrate may be Q235 carbon structural steel or 310 heat-resistant stainless steel. The thickness of the cavity can be 18–22 mm, for example, 20 mm.

[0058] The powder material entering from the ore powder inlet forms a column 1-14 under the action of the distribution air device, the ore separating cone and the air regulating cone, and the material is discharged evenly.

[0059] The air distribution device can be an air distribution ring or an air distribution hole.

[0060] The heat insulation board does not affect the material feeding; it only blocks the radiant heat of the high-temperature reducing gas inside the reduction furnace column cavity. This invention does not impose any special restrictions on the material of the heat insulation board; it can be high-temperature resistant fiber cotton, nanofiber board, or aerogel insulation sheet.

[0061] In some embodiments of the present invention, the process air outlet of the swirling nozzle is bolted to the top of the reduction furnace column cavity.

[0062] In some embodiments of the present invention, the bottom of the reduction furnace cylindrical cavity is connected to the reduction furnace conical cavity by welding; or the reduction furnace cylindrical cavity and the reduction furnace conical cavity are integrally formed.

[0063] The present invention does not impose any special restrictions on the material of the reduction furnace column cavity and the reduction furnace cone cavity, and they can be Q235 steel, Q345 steel, or Q235A steel.

[0064] This invention includes a fungicide cap at the connection between the column cavity and the cone cavity of the reduction furnace for dispersing and guiding powdered materials. In some embodiments of this invention, the angle of the top of the fungicide cap does not exceed 70°, for example, 65° to 70°, specifically 68°. The fungicide cap is made of heat-resistant stainless steel, serving to disperse and guide the materials, ensuring not only operational stability and strength at high temperatures, but also acting as a diaphragm to prevent the reduced iron powder from being drawn away. Specifically, the fungicide cap is mounted on a heat-resistant steel structure, which is fixedly connected to the column cavity of the reduction furnace using heat-resistant bolts.

[0065] In some embodiments of the present invention, a hopper is provided at the outlet of the locking hopper.

[0066] The described cyclone direct reduction vertical furnace is a closed-loop reduction reaction tower. It utilizes heated high-reducing-potential gas, injecting material (iron ore powder) into the reduction reaction tower through swirling nozzles. During the process of thorough mixing and swirling descent of the iron ore powder and high-temperature reducing-potential gas, FeO is produced within seconds. x The iron ore is reduced to Fe. The rotating airflow carries the iron ore powder downwards, preventing it from scattering and ensuring the reduced powder doesn't stick to the walls. Near the bottom of the reduction tower, the reduced iron powder is dispersed around the inside of the tower by the action of the mold, flowing evenly down into the cone section (reduction furnace cone cavity). The reduced iron powder collected in the cone section drips into the hopper (hopper 9, described later) for use in hot pelletizing. At 650–750℃, under closed, high-pressure roller pressing, the iron powder is pressed into saucer-shaped pellets with a horizontal diameter of 35–60 mm and a thickness (vertical diameter) of 15–20 mm. The press operates under nitrogen protection to prevent oxidation of the iron powder. The pressed pellets are directly transported to the steelmaking furnace for use or cooled and sold as high-quality metal feedstock. The exhaust port at the bottom of the mold is connected to an exhaust pipe to discharge the exhaust gas, which is then purified before use.

[0067] Specifically, 200-mesh iron ore powder enters the reduction furnace column cavity 1-1-1 through the powder inlet 1-11 of the swirl-type nozzle 1-2. Under the influence of the distribution air entering through the distribution air inlet 1-12 and the large amount of high-temperature, high-reducing-potential gas entering through the high-temperature reducing carrier gas inlet 1-10, the powder passes through the nozzle channel. To prevent material adhesion, the gas-solid ratio is controlled at 5–10 kg / Nm³. 3Under the action of the distribution air device 1-7, the ore-separating cone 1-8, and the regulating air cone 1-9, the material column is ensured to have a certain radius and uniform feeding (the feeding rate is related to the output setting). To prevent nozzle overheating when a certain amount of CO is present or natural gas is injected (entering through process air inlet 1-10), heat insulation plate 1-6 is used to protect the lower end of the nozzle. The powder material and process gas descend in a hurricane-like motion, undergoing explosive mass transfer, heat transfer, and reduction reactions simultaneously, producing FeO. x The reduced iron is converted to Fe and drifts down to the bottom of the reduction furnace. To facilitate the treatment of excess unreacted reducing gas in the exhaust gas pipes 1-5, as well as to separate dust and prevent low-melting-point substances from sticking together, mushroom caps 1-4 are installed in the conical section of the reduction furnace. The angle of the mushroom cap top is below 70°, and the size is designed according to the capacity of the reduction furnace. The reduced iron powder is collected in sections by the locking hoppers 1-3 and discharged in batches to the next process, where it is briquetteed into hot briquettes or directly smelted into steel in an electric furnace.

[0068] The present invention also provides a system for direct ironmaking by swirl flotation, comprising:

[0069] Cyclone direct reduction vertical shaft furnace;

[0070] A waste heat boiler connected to the tail gas pipe of the aforementioned airflow cyclone direct reduction vertical furnace;

[0071] A cyclone dust collector connected to the gas outlet of the waste heat boiler;

[0072] A scrubbing tower connected to the gas outlet of the cyclone dust collector;

[0073] An absorption tower is connected to the gas outlet of the spraying tower; the gas outlet of the absorption tower is provided with two paths; the first path is connected to a heating furnace; the gas outlet of the heating furnace is connected to the process air inlet of the airflow cyclone direct reduction vertical furnace; the second path is connected to a feeding tank; the outlet of the feeding tank is connected to the ore powder inlet of the airflow cyclone direct reduction vertical furnace.

[0074] The top of the feeding tank is provided with a feeding port; the feeding port of the feeding tank is connected to the locking hopper; the top of the locking hopper is provided with a feeding port; the feeding port of the locking hopper is connected to the silo.

[0075] The gas flow cyclone direct reduction vertical furnace is the gas flow cyclone direct reduction vertical furnace described above.

[0076] Figure 2 This is a system diagram of a cyclone direct ironmaking system provided according to an embodiment of the present invention. In the diagram, 1 is a vertical shaft furnace for direct reduction using a cyclone airflow system, 2 is a waste heat boiler, 3 is a cyclone dust collector, 4 is a spraying tower, 5 is an absorption tower, 6 is a heating furnace, 7 is a feeding tank, 8 is a locking hopper, and 9 is a silo.

[0077] In this invention, the waste heat boiler is further equipped with a steam outlet. The waste heat boiler is used for heat exchange of the tail gas from a cyclone direct reduction vertical furnace, reducing the tail gas temperature while producing steam as a byproduct. Therefore, the waste heat boiler is used to absorb waste heat and produce steam for external utilization. Simultaneously, it reduces washing water consumption, thereby lowering operating costs. This invention does not impose any special limitations on the structure and type of the waste heat boiler; structures and types of waste heat boilers well known to those skilled in the art can be used.

[0078] In some embodiments of the present invention, a Venturi mixer is installed on the pipeline between the waste heat boiler and the cyclone dust collector to humidify and cool the exhaust gas discharged from the waste heat boiler.

[0079] The cyclone dust collector is used for dust removal from gas. This invention does not impose any special limitations on the structure and type of the cyclone dust collector; structures and types of cyclone dust collectors well-known to those skilled in the art can be used.

[0080] The spraying solution used in the spraying tower is fresh industrial water. This invention does not impose any special limitations on the structure and type of the spraying tower; any structure and type of spraying tower well-known to those skilled in the art can be used.

[0081] The absorption tower is used to remove carbon dioxide from the gas. This invention does not impose any special limitations on the structure and type of the absorption tower; structures and types of absorption towers well-known to those skilled in the art can be used. The gas discharged from the absorption tower is a decarbonization reducing gas.

[0082] In this invention, the first outlet of the gas from the absorption tower is connected to the decarbonized gas inlet of the heating furnace. A portion of the decarbonized reducing gas discharged from the absorption tower enters the heating furnace via the decarbonized gas inlet. In some embodiments of this invention, the heating furnace is further provided with a reducing gas inlet (i.e., a fresh reducing gas inlet). The reducing gas includes at least one of natural gas, syngas, and hydrogen. When natural gas is used as the gas source, a reforming heating furnace is employed; when syngas or hydrogen is used as the gas source, a tubular heating furnace, an electric heating furnace, or a plasma heating device can be employed. The heating furnace is used for mixing and heating the reducing gas with a portion of the decarbonized reducing gas discharged from the absorption tower, thereby fully utilizing the gas and reducing energy consumption.

[0083] The second outlet of the gas from the absorption tower is connected to the feed tank. Another portion of the decarbonization reducing gas discharged from the absorption tower is used as part of the process gas in the feed tank, serving as the energy source for system pressure equalization and fine ore transportation. It also has reducing properties, thus acting as both a power source and a process reducing gas.

[0084] In some embodiments of the present invention, the hopper is further provided with a carrier gas inlet. The carrier gas includes at least one of nitrogen and carbon dioxide. Carbon dioxide, as a by-product gas of this system, can minimize additional nitrogen consumption and reduce operating costs.

[0085] In some embodiments of the present invention, the silo is provided with an iron ore powder inlet.

[0086] In some embodiments of the present invention, the dust outlet at the bottom of the cyclone dust collector is connected to the silo; the dust outlet at the bottom of the spray tower is connected to the silo.

[0087] The present invention also provides a method for direct ironmaking using the system described above, comprising the following steps:

[0088] S1) Iron ore powder is injected into a cyclone direct reduction vertical furnace through a swirling nozzle using a high-temperature reducing carrier gas of 850-1200℃. The powder rotates, floats, and descends, undergoing physicochemical reactions involving mass and heat transfer during its descent to obtain iron powder. The obtained iron powder is dispersed and guided by a funnel and enters the cone cavity of the reduction furnace before entering the lock hopper. The tail gas is discharged through the tail gas pipe.

[0089] S2) The exhaust gas obtained in step S1) is cooled by heat exchange in a waste heat boiler. The temperature of the exhaust gas after cooling is 270-290°C. After being humidified by water spraying, the temperature of the exhaust gas is further reduced to below 180°C.

[0090] S3) Remove dust from the gas processed in step S2);

[0091] S4) Spray the gas processed in step S3) to wash it;

[0092] S5) Remove carbon dioxide from the gas processed in step S4);

[0093] S6) After mixing and heating a portion of the gas processed in step S5) with fresh reducing gas, it is reused as the high-temperature reducing carrier gas in the gas flow cyclone direct reduction vertical furnace.

[0094] Another portion of the gas processed in step S5) is mixed with the carrier gas carrying iron ore powder and then reused for the iron ore powder in the gas flow cyclone direct reduction shaft furnace.

[0095] Regarding step S1):

[0096] Iron ore powder is injected into a cyclone direct reduction vertical furnace through a swirling nozzle using a high-temperature reducing carrier gas at 850–1200℃. The powder rotates, floats, and descends, undergoing physicochemical reactions involving mass and heat transfer during its descent to obtain iron powder. The obtained iron powder is then dispersed and guided by a funnel and enters the cone cavity of the reduction furnace before entering the lock hopper. The tail gas is discharged through a tail gas pipe.

[0097] The swirling nozzle is the swirling nozzle described above.

[0098] In some embodiments of the present invention, the iron ore powder is a medium-to-low grade iron ore powder; the iron content in the iron ore powder is 50% to 65% by mass. For example, at least one of hematite, magnetite, and vanadium-titanium magnetite. The particle size of the iron ore powder is 200 mesh, and the moisture content is controlled to be less than 1%. For iron ore powder whose particle size does not meet the requirements, it can be ground to 200 mesh using a ball mill.

[0099] In some embodiments of the present invention, the high-temperature reducing carrier gas comprises at least one of natural gas, syngas, and hydrogen. In syngas containing a high concentration of CO, the reaction is predominantly exothermic; however, in high H2 concentrations or with pure hydrogen, the reaction is endothermic, requiring temperatures above 1000°C for optimal performance.

[0100] In some embodiments of the present invention, iron ore powder is passed through a high-temperature reducing carrier gas at 850–1200°C, and the gas-solid ratio is controlled to be 5–10 kg / Nm³. 3 For example, 8kg / Nm 3 .

[0101] The flow rate injected by the swirling nozzle can be determined according to the design capacity. For a capacity of 10,000 tons, it is 0.8 to 1.2 t / h, such as 1 t / h; for a capacity of one million tons or more, it is 430 to 470 t / h, such as 450 t / h.

[0102] In this invention, iron ore powder is injected into a cyclone-type direct reduction vertical furnace through a swirling nozzle, where it rotates, floats, and descends. During this descent, physicochemical reactions involving mass and heat transfer occur, yielding iron powder. Specifically, iron ore powder is suspended and descends by a cyclone, undergoing mass, heat, and chemical reactions during its descent to obtain iron powder. The chemical reaction is a reduction reaction.

[0103] In some embodiments of the present invention, the physicochemical reaction takes 3 to 5 seconds, for example, 4 seconds.

[0104] In this invention, under a working environment with a gas-to-solid ratio of 5–10 kg / m³, due to the high specific surface area of ​​the ore powder, the reducing gas and the material undergo explosive mass transfer, heat transfer, and chemical reactions, which can be completed in 3–5 seconds. With increasing temperature and smaller particle size, the reaction time is even shorter. This invention flexibly employs a swirling nozzle, high-temperature reducing gas as a carrier, a mushroom-type finished product collection system, a lock hopper-type finished product collection system, and hot-pressing, ensuring the smooth operation and reliability of the process. It provides an economical and low-carbon path for the rapid iron production from medium- and low-grade iron ore in industrial engineering.

[0105] In this invention, columnar swirling material floats and descends within the reduction vertical furnace, preventing it from sticking to the furnace wall, ensuring smooth production, reducing friction, improving the service life of refractory materials, and facilitating the feeding of raw materials into containers.

[0106] Regarding step S2):

[0107] The exhaust gas obtained in step S1) is cooled by heat exchange in a waste heat boiler to a temperature of 275-285°C. After being humidified by water spraying, the temperature of the exhaust gas is further reduced to below 180°C.

[0108] In this invention, after being humidified by water spraying, the exhaust gas temperature is further reduced to below 180°C; at the same time, large-diameter "water-encased dust" particles are formed in the exhaust gas, with dust as the condensation nucleus.

[0109] Regarding step S3):

[0110] The gas processed in step S2) is then subjected to dust removal.

[0111] The dust removal is carried out in a cyclone dust collector.

[0112] In step S2), large-diameter "water-encased dust" particles are formed in the treated gas, which can improve dust removal efficiency. The gas enters a cyclone dust collector and removes dust under the action of centrifugal force. Compared with traditional cyclone dust collectors, this invention can remove dust with smaller particle size.

[0113] The dust obtained from dust removal can enter the silo for use in heated briquetting.

[0114] Regarding step S4):

[0115] The gas processed in step S3) is then sprayed and washed.

[0116] The spraying is carried out in a spraying tower. The spraying fluid used is fresh industrial water. Using fresh industrial water for spraying and washing removes dust from the gas. The resulting dust can be fed into a silo for use in hot briquetting.

[0117] Regarding step S5):

[0118] The gas processed in step S4) is subjected to carbon dioxide removal.

[0119] This invention does not impose any special limitations on the composition of the absorbent used for carbon dioxide removal; any amine solution well-known to those skilled in the art can be used. Specifically, the absorbent used for carbon dioxide removal includes MEDA, an active agent, and water. The active agent is selected from MEA, DEA, or PZ. Specifically, in the absorbent, the mass content of MEDA is 40% to 50%, for example, 45%; and the mass content of the active agent is 3% to 8%, for example, 5%.

[0120] Regarding step S6):

[0121] After a portion of the gas processed in step S5) is mixed with fresh reducing gas and heated, it is reused as the high-temperature reducing carrier gas in the gas flow cyclone direct reduction vertical furnace.

[0122] Another portion of the gas processed in step S5) is mixed with the carrier gas carrying iron ore powder and then reused for the iron ore powder in the gas flow cyclone direct reduction shaft furnace.

[0123] In some embodiments of the present invention, the fresh reducing gas is at least one of natural gas, syngas, and hydrogen.

[0124] In some embodiments of the present invention, the volume ratio of one part of the gas to another part of the gas after step S5) is 1.5 to 2.5:1, for example 2:1.

[0125] In some embodiments of the present invention, a portion of the gas processed in step S5) is mixed with fresh reducing gas and heated to a temperature of 850–1200°C.

[0126] In some embodiments of the present invention, the volume ratio of a portion of the gas after step S5) to fresh reducing gas is 1.5 to 2.5:1, for example 2:1.

[0127] In some embodiments of the present invention, the volume ratio of another portion of the gas after step S5) to the carrier gas carrying iron ore powder is 1.5 to 2.5:1, for example 2:1.

[0128] The carrier gas is selected from at least one of nitrogen and carbon dioxide.

[0129] In this invention, the entire process does not require pellets, sinter, or coke as required by other ironmaking processes. Compared with blast furnace ironmaking, the new technology will significantly reduce energy consumption by 30%–60% and carbon dioxide emissions by 60%–96%, depending on whether hydrogen or hydrocarbon gases are used. This invention avoids problems such as particle adhesion or particle disintegration. Given the global scarcity of high-grade iron ore and the inability to comprehensively utilize difficult-to-process ores, this invention provides an economical, reliable, and efficient technological solution. Specifically, the reduction furnace in this invention uses a 380t / h nozzle equivalent to a 2000m³ blast furnace and does not require supporting coking, sintering, pelletizing, or flux plants, thus saving significant fixed investment, reducing land area, and achieving completely zero-carbon iron and steel production.

[0130] To further illustrate the present invention, the following detailed description of the system and method for direct reduction shaft furnace and direct ironmaking by cyclone flow provided by the present invention is provided in conjunction with embodiments, but it should not be construed as a limitation on the scope of protection of the present invention.

[0131] Example 1

[0132] Adopting such Figure 1 The illustrated cyclone direct reduction vertical furnace includes:

[0133] The reduction furnace column cavity 1-1-1; a swirling nozzle 1-2 is provided at the top of the reduction furnace column cavity 1-1-1;

[0134] A reduction furnace conical cavity 1-1-2 is fixedly connected to the bottom of the reduction furnace cylindrical cavity 1-1-1; a mushroom cap 1-4 (with a top angle of 68° and made of heat-resistant stainless steel) is provided at the connection between the reduction furnace cylindrical cavity 1-1-1 and the reduction furnace conical cavity 1-1-2 to disperse the powder and allow it to enter the reduction furnace conical cavity 1-1-2 evenly; a tail gas outlet is provided at the bottom of the mushroom cap 1-4;

[0135] Exhaust pipes 1-5 connected to the exhaust outlet;

[0136] A locking hopper 1-3 is provided at the bottom of the cone cavity of the reduction furnace;

[0137] A hopper 9 is provided at the outlet of the locking hoppers 1-3.

[0138] The fungal cap 1-4 is mounted on a heat-resistant steel structure, and the heat-resistant steel structure is fixedly connected to the reduction furnace column cavity 1-1-1 by heat-resistant bolts.

[0139] Both the cylindrical cavity and the conical cavity of the reduction furnace are made of Q235 steel.

[0140] The structure of the swirling nozzle 1-2 is as follows: Figure 1As shown, it includes:

[0141] An inverted conical cavity 1-13 (made of 310 heat-resistant stainless steel, 20mm thick); a mineral powder inlet 1-11 and a distribution air inlet 1-12 are sequentially arranged at the top center of the cavity in a direction away from the cavity; two process air inlets 1-10 are arranged at the top of the cavity near the edge, with the two process air inlets located on both sides of the top center respectively.

[0142] An outlet is provided at the bottom of the cavity; an air regulating cone 1-9 is provided at the outlet of the cavity; a ore separating cone 1-8 is provided at the outlet of the air regulating cone 1-9; a distribution air device 1-12 (distribution air hole) is provided at the bottom of the ore separating cone 1-8; a heat insulation plate 1-6 (nanofiber plate) is provided at the bottom of the distribution air device; the material powder entering from the mineral powder inlet forms a material column 1-14 under the action of the distribution air device 1-12, the ore separating cone 1-8 and the air regulating cone 1-9, and the material is discharged evenly;

[0143] The outlet of the cavity is connected to the top of the reduction furnace column cavity 1-1-1.

[0144] The process air outlet of the swirling nozzle is bolted to the top of the reduction furnace column cavity.

[0145] cyclone direct ironmaking systems such as Figure 2 As shown, it includes:

[0146] 1. Direct reduction vertical furnace with airflow cyclone type;

[0147] Waste heat boiler 2 is connected to the tail gas pipe of the airflow cyclone direct reduction vertical furnace 1;

[0148] Cyclone dust collector 3 is connected to the gas outlet of the waste heat boiler 2;

[0149] A spray scrubbing tower 4 is connected to the gas outlet of the cyclone dust collector 3;

[0150] An absorption tower 5 is connected to the gas outlet of the spraying tower 4; the gas outlet of the absorption tower 5 is provided with two paths; the first path is connected to the heating furnace 6; the gas outlet of the heating furnace 6 is connected to the process air inlet of the airflow cyclone direct reduction vertical furnace 1; the second path is connected to the feeding tank 7; the outlet of the feeding tank 7 is connected to the ore powder inlet of the airflow cyclone direct reduction vertical furnace 2.

[0151] The top of the feeding tank 7 is provided with a feeding port; the feeding port of the feeding tank 7 is connected to the locking hopper 8; the top of the locking hopper 8 is provided with a feeding port; the feeding port of the locking hopper 8 is connected to the silo 9.

[0152] The waste heat boiler 2 is also equipped with a steam outlet for heat exchange of the tail gas from the airflow cyclone direct reduction vertical furnace, which reduces the tail gas temperature and produces steam as a byproduct.

[0153] The first outlet of the gas from the absorption tower 5 is connected to the decarbonization gas inlet of the heating furnace 6. The second outlet of the gas from the absorption tower 5 is connected to the feeding tank 7.

[0154] The heating furnace 6 is also equipped with a reducing gas inlet (i.e., a fresh reducing gas inlet).

[0155] The locking hopper 8 is also equipped with a carrier gas inlet.

[0156] The silo 9 is equipped with an iron ore powder inlet.

[0157] A Venturi mixer is installed on the pipeline between the waste heat boiler 2 and the cyclone dust collector 3 to humidify and cool the exhaust gas discharged from the waste heat boiler.

[0158] The dust outlet at the bottom of the cyclone dust collector 3 is connected to the silo 9; the dust outlet at the bottom of the spray tower 4 is connected to the silo 9.

[0159] The method of direct ironmaking by swirl flotation includes the following steps:

[0160] 1) Iron ore powder is reduced by carrier gas at a high temperature of 990-1000℃ (gas-solid ratio controlled at 8 kg / Nm³). 3 The iron powder is injected into the cyclone direct reduction vertical furnace through a swirling nozzle, rotates and floats down, and undergoes a physicochemical reaction involving mass and heat transfer for 4 seconds during the descent to obtain iron powder. The obtained iron powder is dispersed and guided by the fungal cap and enters the cone cavity of the reduction furnace, and then enters the lock hopper. The tail gas is discharged through the tail gas pipe.

[0161] The iron ore powder is hematite; the iron content in the iron ore powder is 60% by mass. The particle size of the iron ore powder is 200 mesh, and the moisture content is controlled to be less than 1%.

[0162] The high-temperature reducing carrier gas is composed of natural gas; when natural gas is used as the gas source, the heating furnace is a reforming heating furnace;

[0163] 2) The exhaust gas obtained in step 1) is cooled by heat exchange in a waste heat boiler to a temperature of 270-290°C. After being humidified by water spraying, the temperature of the exhaust gas is further reduced to 165-175°C. At the same time, large-diameter "water-encased dust" particles are formed in the exhaust gas with dust as condensation nuclei.

[0164] 3) The gas processed in step 2) is dusted by a cyclone dust collector; the dust obtained from the dust removal can enter the silo for use in hot briquetting.

[0165] 4) The gas processed in step 3) is sprayed and washed to remove dust from the gas; the spraying liquid used is fresh industrial water; the obtained dust can enter the silo for use in hot briquetting.

[0166] 5) Remove carbon dioxide from the gas treated in step 4):

[0167] The absorbent used for carbon dioxide removal consists of MEDA, an active agent, and water; the active agent is selected from MEA. The absorbent contains 45% MEDA by mass and 5% active agent by mass.

[0168] 6) A portion of the gas processed in step 5) is mixed with fresh reducing gas (natural gas) and heated to 1100-1110°C, and then reused as the high-temperature reducing carrier gas in the gas flow cyclone direct reduction vertical furnace; the volume ratio of a portion of the gas processed in step 5) to another portion of the gas is 2:1.

[0169] Another portion of the gas processed in step S5) is mixed with the carrier gas carrying iron ore powder and then reused for iron ore powder in the gas flow cyclone direct reduction shaft furnace. The volume ratio of the other portion of the gas processed in step S5) to the carrier gas carrying iron ore powder is 2:1. The carrier gas is selected from carbon dioxide (including carbon dioxide, a by-product gas of this system).

[0170] The volume ratio of one part of the gas to another part of the gas after step 5) is 2:1.

[0171] In this embodiment, the physicochemical reaction time in step 1) is only 4 seconds, which is relatively short. For blast furnace ironmaking, the time from charging to tapping is currently 8-12 hours, while for vertical shaft furnaces it is 6 hours from charging to product output.

[0172] The total CO2 emissions of steel production enterprises are equal to the sum of all fossil fuel combustion emissions, industrial production process emissions, and CO2 emissions implied by net purchased electricity and net purchased heat within the enterprise boundary. The emissions implied by carbon sequestration products should also be deducted. The calculation is based on formula (1).

[0173] E CO2 =E 燃烧 +E 过程 +E 电和热 -R 固碳 Equation (1);

[0174] In formula (1):

[0175] E CO2 This represents the total CO2 emissions of the enterprise, expressed in tons (t).

[0176] E燃烧 CO2 emissions from all net fossil fuel combustion activities of a company, expressed in tons (t);

[0177] E 过程 CO2 emissions generated during the industrial production process of an enterprise, expressed in tons (t);

[0178] E 电和热 CO2 emissions from net purchased electricity and net purchased heat for enterprises, expressed in tons (t);

[0179] R 固碳 This represents the CO2 emissions implied by a company's carbon sequestration products, expressed in tons (t).

[0180] Based on the current status of traditional steelmaking, process energy consumption, and emission factors from the North China Power Grid, the comprehensive carbon emissions of 1 ton of steel throughout its entire lifecycle are calculated as follows:

[0181] 1) Carbon emissions from a typical blast furnace-converter process

[0182] Based on a typical blast furnace converter process, the carbon emissions of converter steel are calculated as follows: 1819.89 kg / t of CO2 is emitted per ton of steel. See Table 1 for details.

[0183] Table 1 Carbon Emissions of Typical Blast Furnace-Converter Process

[0184]

[0185] As can be seen from Table 1, the blast furnace process accounts for more than 70% of both energy consumption and carbon emissions in the smelting process of 1 ton of steel, making it a veritable major carbon emitter.

[0186] 2) Carbon dioxide emissions from the process of this invention

[0187] Based on the electricity emission factor, the average emission factor of the regional power grid in 2012 was selected from the value of 0.8843 kgCO2 / kWh for North China. The calculated energy consumption values ​​for the process are shown in Table 2.

[0188] Table 2 Carbon dioxide emission data for each process

[0189]

[0190]

[0191] As can be seen, when hydrogen is used, the CO2 emission data is 93.12 kg / t DRI.

[0192] The descriptions of the above embodiments are merely illustrative of the methods and core ideas of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gas flow cyclone direct reduction vertical shaft furnace, comprising: The column cavity of the reduction furnace; A swirling nozzle is installed at the top of the cylindrical cavity of the reduction furnace; A cone-shaped cavity of a reduction furnace that is fixedly connected to the bottom of the cylindrical cavity of the reduction furnace; A fungal cap is installed at the connection between the cylindrical cavity and the conical cavity of the reduction furnace to disperse the powder and allow it to enter the conical cavity of the reduction furnace evenly. An exhaust port is provided at the bottom of the mushroom cap; An exhaust pipe connected to the exhaust outlet; A locking hopper is provided at the bottom of the cone cavity of the reduction furnace.

2. The airflow cyclone direct reduction vertical furnace according to claim 1, characterized in that, The swirling nozzle includes: An inverted cone-shaped cavity; a mineral powder inlet and a distribution air inlet are sequentially arranged at the top center of the cavity in a direction away from the cavity; two process air inlets are arranged at the top of the cavity near the edge, with the two process air inlets located on both sides of the top center; An outlet is provided at the bottom of the cavity; an air regulating cone is provided at the outlet of the cavity; a ore separating cone is provided at the outlet of the air regulating cone; a distribution air device is provided at the bottom of the ore separating cone; a heat insulation plate is provided at the bottom of the distribution air device; the material powder entering from the ore powder inlet forms a material column under the action of the distribution air device, the ore separating cone and the air regulating cone and the material is discharged evenly. The outlet of the cavity is connected to the top of the column cavity of the reduction furnace.

3. The airflow cyclone direct reduction vertical furnace according to claim 1, characterized in that, The angle of the top of the mushroom cap does not exceed 70°.

4. A system for direct ironmaking by swirl flotation, comprising: Cyclone direct reduction vertical shaft furnace; A waste heat boiler connected to the tail gas pipe of the aforementioned airflow cyclone direct reduction vertical furnace; A cyclone dust collector connected to the gas outlet of the waste heat boiler; A scrubbing tower connected to the gas outlet of the cyclone dust collector; An absorption tower is connected to the gas outlet of the spraying tower; the gas outlet of the absorption tower is provided with two paths; the first path is connected to a heating furnace; the gas outlet of the heating furnace is connected to the process air inlet of the airflow cyclone direct reduction vertical furnace; the second path is connected to a feeding tank; the outlet of the feeding tank is connected to the ore powder inlet of the airflow cyclone direct reduction vertical furnace. The top of the feeding tank is provided with a feeding port; the feeding port of the feeding tank is connected to the locking hopper; the top of the locking hopper is provided with a feeding port; the feeding port of the locking hopper is connected to the silo. The gas flow cyclone direct reduction vertical furnace is the gas flow cyclone direct reduction vertical furnace as described in any one of claims 1 to 3.

5. A method for direct ironmaking by swirl flotation, comprising the following steps: S1) Iron ore powder is injected into a cyclone direct reduction vertical furnace through a swirling nozzle using a high-temperature reducing carrier gas of 850-1200℃. The powder rotates, floats, and descends, and during the descent, physicochemical reactions involving mass and heat transfer occur to obtain iron powder. The obtained iron powder is dispersed and guided by the bacteria and enters the cone cavity of the reduction furnace, and then enters the lock hopper; Exhaust gas is discharged through the exhaust pipe; S2) The exhaust gas obtained in step S1) is cooled by heat exchange in a waste heat boiler. The temperature of the exhaust gas after cooling is 270-290°C. After being humidified by water spraying, the temperature of the exhaust gas is further reduced to below 180°C. S3) Remove dust from the gas processed in step S2); S4) Spray the gas processed in step S3) to wash it; S5) Remove carbon dioxide from the gas processed in step S4); S6) After mixing and heating a portion of the gas processed in step S5) with fresh reducing gas, it is reused as the high-temperature reducing carrier gas in the gas flow cyclone direct reduction vertical furnace. Another portion of the gas processed in step S5) is mixed with the carrier gas carrying iron ore powder and then reused for the iron ore powder in the gas flow cyclone direct reduction shaft furnace.

6. The method according to claim 5, characterized in that, In step S1), the iron ore powder is a medium-to-low grade iron ore powder; the iron content in the iron ore powder is 50% to 65% by mass. The iron ore powder has a particle size of 200 mesh and a moisture content of less than 1%.

7. The method according to claim 5, characterized in that, In step S1), the components of the high-temperature reducing carrier gas include at least one of natural gas, syngas, and hydrogen. Iron ore powder is reduced with carrier gas at a high temperature of 850–1200℃, with the gas-solid ratio controlled at 5–10 kg / Nm³. 3 .

8. The method according to claim 5, characterized in that, In step S1), the physicochemical reaction takes 3 to 5 seconds.

9. The method according to claim 5, characterized in that, The spraying solution used in the spraying process is fresh industrial water; The absorbent used for carbon dioxide removal includes MEDA, an active agent, and water; the active agent is selected from MEA, DEA, or PZ.

10. The method according to claim 5, characterized in that, In step S6), the volume ratio of one part of the gas to another part of the gas after the treatment in step S5) is 1.5 to 2.5:1; A portion of the gas processed in step S5) is mixed with fresh reducing gas and heated to a temperature of 850–1200°C. The volume ratio of a portion of the gas processed in step S5) to fresh reducing gas is 1.5 to 2.5:

1. In step S5), the volume ratio of the other part of the gas after treatment to the carrier gas carrying iron ore powder is 1.5 to 2.5:

1. The carrier gas is selected from at least one of nitrogen and carbon dioxide.

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