Preparation method of high-metallization-ratio DRI and direct steelmaking method

Abstract

The invention relates to the technical field of ferrous metallurgy, in particular to a preparation method of high-metallization-ratio DRI and a direct steelmaking method. The preparation method of the high-metallization-ratio DRI comprises a fluidized bed process, a cooling process, a fine crushing process and a magnetic separation process. The method can be suitable for direct steelmaking of low-grade iron ore powder. Direct steelmaking refers to that iron in iron ore powder does not need to be melted into molten iron before steelmaking. According to the method, a low-temperature method of fine crushing and magnetic separation is used for replacing a high-temperature method of melting separation, so that an iron-making process is omitted, and carbon emission and huge cost consumption caused by addition of carbon elements during iron-making and decarburization with a large amount of energy during steel-making are avoided.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, specifically a method for preparing high metallization rate DRI and a direct steelmaking method. Background Technology

[0002] Using gas-solid reduction to obtain sponge iron, which can then be directly fed into a steelmaking furnace, avoids the numerous environmentally unfriendly problems associated with blast furnaces, sintering, coking, and pelletizing processes. Especially when using hydrogen to produce sponge iron, zero carbon dioxide emissions can be achieved, a widely accepted direction. However, its adoption has been slow for many years. The fundamental reason is that the two currently used processes for obtaining sponge iron through gas-solid reduction rely on vertical shaft furnaces or fluidized beds, both of which have insurmountable drawbacks. The main drawback of vertical shaft furnaces is the necessity of pelletizing, which severely limits the types of iron ore powder that can be used. The main drawbacks of fluidized beds are significant heat diffusion losses during production, high power consumption for fluidized bed blasting, severe particle adhesion within the fluidized bed, and, more importantly, the low iron content of the main source of coarse ore after fluidized bed reduction, which is unacceptable for steelmaking processes. Therefore, direct steelmaking is not possible; the iron must first be refined into molten iron before being sent to the steelmaking process. This process of refining sponge iron into molten iron not only increases production costs but also generates substantial carbon dioxide emissions. These drawbacks result in the overall cost of both processes being significantly higher than that of the blast furnace process, making them unsuitable for the market.

[0003] Although the Chinese patent document CN111961784A (application number 202010898285.0) proposes magnetic separation of DRI (sponge iron or direct reduced iron), the magnetic separation method of this patent is inefficient and wastes a lot of heat. At the same time, in order to avoid adhesion and loss of flow in the fluidized bed, this patent requires the addition of coal to the fluidized bed. However, coal powder will produce tar in the fluidized bed, which will also cause the material to stick together. Therefore, the effect of solving adhesion and loss of flow by coal powder is not significant. Instead, it will increase the energy consumption of the fluidized bed and increase carbon dioxide emissions, which does not meet the requirements of the dual carbon trend.

[0004] While POSCO's patent CN104185686A (application number 201280064020.4) proposes magnetic separation using DRI (Distilled Reduction), the low temperature setting of the fluidized bed to ensure separation results in poor reduction. Lacking effective cooling, particle size separation, and fine crushing methods, particularly efficient magnetic separation methods, which are strongly correlated with magnetic separation efficiency, the patent limits its efforts to hot magnetic separation of only 10-20% of ultrafine particles selected from its developed dual-fluidized bed reactor. Consequently, the proportion of metallic iron in the product falls far short of steelmaking requirements. Therefore, POSCO's patent aims only to partially address the problem of excessive slag and high costs associated with smelting and ironmaking from low-grade ore powder.

[0005] This invention provides a technical solution to address the aforementioned defects of fluidized beds, and also resolves the technical deficiencies of the two patents mentioned above. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing high-metallization-rate DRI and directly steelmaking. This invention is applicable to the direct steelmaking of low-grade iron ore powder. Direct steelmaking refers to the process of steelmaking without first melting the iron in the iron ore powder into molten iron. This invention uses a low-temperature method of fine crushing and magnetic separation instead of the high-temperature method of melting, eliminating the ironmaking process and avoiding the addition of carbon elements during ironmaking, followed by the energy-intensive decarburization during steelmaking, which results in carbon dioxide emissions and huge costs.

[0007] Glossary of terms in this invention: Fluidized bed group: This can refer to a multi-stage fluidized bed, i.e., a system composed of multiple independent fluidized beds connected in series or parallel. It can also refer to a single, independently configured fluidized bed, including fluidized beds with different numbers of layers (single-layer and multi-layer fluidized beds), fluidized beds with different fluidization patterns (circulating beds, bubbling beds, etc.), and fluidized beds with different bed types (conical beds, cylindrical beds, etc.). See the specific limitations of each scheme for details.

[0008] Fluidized bed sequencing: The fluidized beds are sequenced according to the order in which the reducing gas enters. The fluidized bed into which the reducing gas enters is the first-stage fluidized bed, and the fluidized bed into which the reducing gas exits is the last-stage fluidized bed. This is indicated by R followed by a number in the attached diagram.

[0009] Tailings: refers to iron powder particles with low iron content remaining after the magnetic separation process provided by this invention, and is not tailings remaining in the field of mineral processing.

[0010] Iron ore powder: The iron ore powder used in this invention is all low-grade iron ore powder; Fluidized bed reduction process: includes reducing gas reduction and reducing gas mixed with coal at no more than 50% of the iron ore powder mass.

[0011] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution: A production apparatus for high metallization rate DRI includes a fluidized bed assembly, a fine crushing device, and a magnetic separation device. The inlet of the fine crushing device is connected to the fluidized bed group, and / or the outlet of the fine crushing device is connected to the fluidized bed group; The inlet of the magnetic separator is connected to the fluidized bed assembly, and / or the inlet of the magnetic separator is connected to the fine crushing device; The fluidized bed assembly is equipped with a low-temperature reducing gas inlet and a high-temperature reducing gas inlet, or the production equipment for the high metallization rate DRI also includes a cooling device.

[0012] The fine crushing device is a conventional piece of equipment for various crushing and powdering processes; the fine crushing device is sequentially connected to the pre-selection chamber and the magnetic separation device; more preferably, the magnetic separation device is conventional equipment. The grade of the magnetic separation will be determined comprehensively based on all products of the production line, preferably above 90%. Specifically, the magnetic separation device is selected from various existing dry magnetic separators. It can also be selected from the novel magnetic separation devices that differ from existing technologies as described in the embodiments of this invention.

[0013] This invention also discloses a method for preparing high metallization DRI using the above-mentioned high metallization DRI production equipment, comprising the following steps: Fluidized bed process: Iron is produced by reducing gas and low-grade iron ore powder (hereinafter referred to as iron ore powder) that, even when produced with high metallization rate as DRI, still cannot meet the requirements for direct use in steelmaking, is reduced in the fluidized bed group; Cooling process: When the fluidized bed group is equipped with a low-temperature reducing gas inlet and a high-temperature reducing gas inlet, the material particles are cooled in the fluidized bed group; when the production equipment also includes a cooling device, the cooling device is used to cool the material particles obtained by the fluidized bed process reduction; all or part of the reducing gas is heated and enters the fluidized bed group to react with the iron ore powder, and after the reaction, it flows out of the fluidized bed group and is purified for energy output or recycled by the system.

[0014] Fine crushing process: using a fine crushing device to finely crush iron ore powder, and / or using a fine crushing device to finely crush the material particles obtained from the fluidized bed process reduction; Magnetic separation process: A magnetic separator is used to perform dry magnetic separation on the material particles after the fluidized bed process and the fine crushing process to obtain DRI powder with a high metallization rate; or a magnetic separator is used in the fluidized bed process to perform dry magnetic separation on the material particles flowing out of the fluidized bed group, and the magnetically separated high iron content material is returned to the fluidized bed process for further reduction, finally obtaining DRI powder with a high metallization rate; the proportion of solid metallic iron in the total mass of DRI powder meets the market requirements for steelmaking slag cost.

[0015] The iron ore powder used in this method is mainly coarse powder, which constitutes the majority of the ore source, and its composition is mainly ferric oxide with a particle size of 0-10 mm. If a bubbling fluidized bed is used, the bed thickness depends on the reduction or cooling time; generally, the preferred thickness for a heating reduction bed is 2-3 m. The temperature of the ore powder gradually increases after entering the heating reduction bed, with a preferred high temperature range of 600-850 degrees Celsius. Upon entering the cooling reduction bed, the powder is cooled to a magnetic separation temperature range below the Curie point, preferably 70-50 degrees Celsius. A high reducing potential of the reducing gas is preferable. The initial high-temperature reducing gas temperature entering the heating reduction bed is preferably 650-900 degrees Celsius; the low-temperature reducing gas temperature is preferably 20-200 degrees Celsius. The particle size after fine crushing is generally 8-400 mesh, preferably 50-200 mesh.

[0016] In one type of embodiment of the present invention: The fluidized bed group is a multi-stage bubbling fluidized bed group, preferably with 3 to 6 stages. Reducing gas between adjacent fluidized beds exits from the top of the preceding fluidized bed, enters from the bottom of the following fluidized bed through a reducing gas pipe, and exits from the last fluidized bed. The fluidized bed group is selected from one of the following forms: a) The fluidized bed assembly is a conventional multi-stage bubbling fluidized bed assembly of the prior art: All iron ore powder is added from the last stage fluidized bed, passes through each stage of fluidized bed in sequence, and is discharged from the first stage fluidized bed; b) Compared with the conventional fluidized bed assembly in a), the improvement is that the last stage fluidized bed is a conical bed with a taper of 3~50 degrees on the sidewalls, preferably 15~35 degrees. The top of the fluidized bed layer of the last stage fluidized bed is provided with a fine material outlet pipe, and the bottom is provided with a coarse material outlet pipe and a control valve. The control valve is used to control the discharge flow rate. The taper here, also known as the cone angle, refers to the fact that the inner wall of the fluidized bed's side wall cylinder is not perpendicular to the horizontal plane, but forms a certain angle with the vertical line of the horizontal plane. In the area 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, presenting a "larger at the top and smaller at the bottom" structure.

[0017] By setting the last stage fluidized bed as a conical bed, and through the coarse and fine stratification of mineral powder in the large-cone conical fluidized bed, the fluidized bed becomes a reducing fluidized bed with coarse and fine particle separation function, mainly composed of fine materials, and the rest being a reducing fluidized bed of coarse materials.

[0018] In this fluidized bed assembly of the present invention, iron ore powder first enters the last stage fluidized bed, where the iron ore powder undergoes coarse and fine particle separation. After being reduced in the last stage fluidized bed, the fine particles are discharged through the fine material discharge pipe, while the coarse particles pass through each stage of the fluidized bed sequentially and are discharged from the first stage fluidized bed. Due to the conical bed's structural feature of being larger at the bottom and smaller at the top, the air velocity inside the conical bed tends to be higher at the bottom and lower at the top, thus enabling the separation of coarse and fine particles.

[0019] This invention separates fine and coarse particles and then reduces them in different fluidized beds. Therefore, the reduction temperature of the fine particle fluidized bed can be controlled, effectively avoiding the problem of fluidized bed adhesion and loss of flow while ensuring reduction efficiency.

[0020] c) Compared to the conventional fluidized bed assembly in a), the improvement lies in the fact that the subsequent fluidized bed is equipped with an air separation mechanism, which is connected to the last fluidized bed. The air separation mechanism is used to transfer the fine particles in the iron ore powder entering the next stage fluidized bed to the last stage fluidized bed, so that the last stage fluidized bed is a fine particle reduction bed and the others are coarse particle reduction beds. In this fluidized bed assembly of the present invention, iron ore powder first enters the next stage fluidized bed, and the air separation mechanism transfers the fine particles in the iron ore powder to the last stage fluidized bed. The fine particles are reduced in the last stage fluidized bed and then discharged. The coarse particles pass through each stage of the fluidized bed sequentially from the next stage fluidized bed and are discharged from the first stage fluidized bed. d) Compared to the conventional fluidized bed group in a), the improvement lies in that the fluidized bed group is divided into a coarse particle fluidized bed group and a fine particle fluidized bed group, which are connected to the sorting device: In this fluidized bed assembly of the present invention, before the iron ore powder enters the fluidized bed, it is first separated into coarse particles and fine particles by a sorting device, and then enters the coarse particle fluidized bed assembly and the fine particle fluidized bed assembly respectively for reduction.

[0021] Preferably, the fluidized bed assembly of the present invention further includes the following technical features: e) The fluidized bed group is a cooled multi-stage bubbling fluidized bed group: Specifically, the cooled multi-stage bubbling fluidized bed assembly of the present invention includes the following three forms: The first-stage fluidized bed of the cooling multi-stage bubbling fluidized bed group is a cooling reduction bed, and the other fluidized beds are heating reduction beds; Alternatively, the next-stage fluidized bed in the cooling multi-stage bubbling fluidized bed group is a cooling reduction bed, while the other fluidized beds are heating reduction beds. The material outlet of the next-stage fluidized bed is connected to the next-stage fluidized bed via the magnetic separation device. This scheme is particularly suitable for fluidized beds of type a), where iron ore powder is reduced to magnetite in the last fluidized bed, where the magnetism is at its highest. After being cooled in the next-stage fluidized bed, it enters the magnetic separation device for magnetic separation. The high-grade iron ore powder after magnetic separation enters the next-stage fluidized bed for further reduction. Low-temperature reducing gas is introduced into the next-stage fluidized bed, and the reducing gas outlets of both the next-stage and next-stage fluidized beds are connected to the reducing gas inlet of the last-stage fluidized bed.

[0022] Alternatively, the first-stage fluidized bed of the cooled multi-stage bubbling fluidized bed group is a multi-layer bed, with the bottom 1 to 3 layers of the first-stage fluidized bed being cooled reduction beds, and the remaining layers being heated reduction beds. High-temperature reducing gas enters the first-stage fluidized bed from the bottom of the gas distribution plate of the heated reduction bed adjacent to the cooled reduction bed, and passes through each heated reduction bed in sequence. Low-temperature reducing gas enters the first-stage fluidized bed from the bottom of the lowest gas distribution plate, passes through each cooled reduction bed in sequence, and then merges with the high-temperature reducing gas to enter the heated reduction bed. Finally, it exits from the top layer of the first-stage fluidized bed, then enters the second-stage fluidized bed, and finally exits from the last-stage fluidized bed of the cooled multi-stage bubbling fluidized bed group.

[0023] The term "cooled" in the described multi-stage bubbling fluidized bed refers to the fact that, unlike existing reduction beds which only have a heated reduction bed layer, the fluidized bed provided by this invention also includes a cooling reduction layer. Iron ore powder is primarily cooled in the cooling reduction layer, which offers advantages such as higher heat exchange efficiency, less heat loss, lower investment, and less floor space compared to a separate cooling device. The term "multi-stage" refers to multiple beds arranged laterally and connected by feed and gas pipes, distinguishing it from "multi-layer" fluidized beds that are stacked vertically.

[0024] Preferably, when the fluidized bed group is in the form of a)-d), the cooling of the reduced DRI powder is completed by a cooling device located outside the fluidized bed group; more preferably, when the fluidized bed group is in the form of d), after the fine particles are discharged from the fine particle fluidized bed group, they can also enter a coarse particle fluidized bed group for further reduction, and then enter the cooling device together with the coarse particles, either partially or completely.

[0025] Preferably, when the fluidized bed group is a combination of d) and e), the first-stage fluidized bed is a coarse-particle fluidized bed group: In a scheme where the first-stage fluidized bed is a cooling reduction bed, fine particles are discharged from the fine particle fluidized bed group and then enter the first-stage fluidized bed together with coarse particles, either entirely or partially. Alternatively, in a scheme where the first-stage fluidized bed is a multi-layer bed, after the fine particles are discharged from the fine particle fluidized bed group, they enter the heating and reduction bed of the first-stage fluidized bed for further reduction, and then, together with the coarse particles, enter the cooling and reduction bed of the first-stage fluidized bed in whole or in part.

[0026] Preferably, all or part of the reducing gas discharged from the fluidized bed is collected by a cyclone dust collector before entering the adjacent fluidized bed. Each bed in a cooled multi-stage bubbling fluidized bed is generally a single-layer bed, but it can also be a multi-layer bed. Since each layer of the bubbling bed has an air distribution plate at the bottom, the scouring and wear of the air distribution plate can be reduced by setting up a cyclone dust collector. This is the reason why this method adopts an innovative cooled multi-stage bubbling fluidized bed.

[0027] In another embodiment of the invention: The fluidized bed group is a multi-stage circulating fluidized bed group with 3 to 7 stages; the fluidized bed group is selected from one of the following forms: a) The multi-stage circulating fluidized bed group is a conventional multi-stage circulating fluidized bed group in the prior art: Iron ore powder is added from the last stage fluidized bed, passes through each stage of fluidized bed in sequence, and is discharged from the first stage fluidized bed; b) The fluidized bed is divided into a coarse particle bed and a fine particle bed, and the fluidized bed is connected to a particle classification device: Before entering the fluidized bed, iron ore powder first enters the particle classification device, which separates it into fine particles and coarse particles according to the design requirements. Then, the particles enter the fine particle bed group or the coarse particle bed group respectively to complete the reduction. Furthermore, the fluidized bed assembly further includes the following technical features: c) The multi-stage circulating fluidized bed group is a cooled multi-stage circulating fluidized bed group, with the first stage circulating fluidized bed being a cooled reduction bed and the rest being heated reduction beds: The low-temperature reducing gas enters from the bottom of the first-stage circulating fluidized bed, passes through the first-stage circulating fluidized bed, and then enters the second-stage circulating fluidized bed, where it merges with the high-temperature reducing gas; the first-stage circulating fluidized bed can also be replaced with a bubbling bed.

[0028] Alternatively, the multi-stage circulating fluidized bed group can be a cooled multi-stage circulating fluidized bed group, while other fluidized beds can be heated reduction beds. The material outlet of the next-to-last circulating fluidized bed is connected to the next-to-last secondary circulating fluidized bed through the magnetic separation device. This scheme is particularly suitable for circulating fluidized beds of type a), where iron ore powder is reduced to magnetite in the last circulating fluidized bed, at which point the magnetism is at its highest. After being cooled in the next-to-last circulating fluidized bed, it enters the magnetic separation device for magnetic separation. The high-grade iron ore powder after magnetic separation enters the next-to-last secondary circulating fluidized bed for further reduction. Low-temperature reducing gas is introduced into the next-to-last circulating fluidized bed, and the reducing gas outlets of the next-to-last secondary fluidized bed and the next-to-last primary fluidized bed are both connected to the reducing gas inlet of the last fluidized bed.

[0029] More preferably, when the fluidized bed group is in the form of a) or b), the cooling of the reduced DRI powder is completed by a cooling device outside the fluidized bed group; More preferably, when the fluidized bed group is in the form of b) and c), the first-stage circulating fluidized bed is a coarse-particle bed group. Coarse and fine particles are discharged from their respective bed groups and merged into the first-stage circulating fluidized bed; Low-temperature reducing gas passes through all the bed groups in sequence; The high-temperature reducing gas passes through the fine particle bed in sequence and the coarse particle bed in sequence, or the high-temperature reducing gas is introduced from the second-stage circulating fluidized bed and then passes through each stage of the fluidized bed in sequence.

[0030] When the present invention uses an innovative cooling multi-stage circulating fluidized bed, the air distribution plate can be eliminated, thus avoiding the problem of erosion and wear of the air distribution plate.

[0031] In yet another embodiment of the invention: The fluidized bed group is a multi-layer bubbling fluidized bed, or a series or parallel connection of several multi-layer bubbling fluidized beds.

[0032] Preferably, the multi-layer bubbling fluidized bed is an air-classified multi-layer conical bed, wherein the air-classified multi-layer conical bed is a multi-layer bubbling fluidized bed with an air-classification mechanism, and each fluidized bed layer is a conical bed.

[0033] In a further preferred embodiment, in the air-classified multi-layer cone bed, the bottom layer or the bottom layer plus the second bottom layer is a cooling reduction bed, and the other layers are heating reduction beds. Finally, the reduced DRI powder leaves the air-classified multi-layer cone bed from the bottom cooling reduction bed.

[0034] 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.

[0035] Because of the wide particle size distribution of coarse ore powder, the conical bed can effectively control the separation of the bed, stabilize the bed, reduce the space occupied by each bed, and reduce wear.

[0036] Preferably, in the method for preparing high metallization rate DRI, the fine crushing step is set in one of the following ways: a) The fine crushing process is completed before the fluidized bed process reduction, that is, the iron ore powder is first finely crushed, then enters the fluidized bed group, is reduced in the fluidized bed process, and then cooled and dry magnetically separated; b) First, the iron ore powder is coarsely crushed, then reduced in a fluidized bed process, and then finely crushed after exiting the fluidized bed group, followed by cooling and dry magnetic separation. c) The iron ore powder is reduced in a fluidized bed process, then cooled, finely crushed, and then dry magnetically separated; d) After the iron ore powder enters the fluidized bed process for reduction, it exits the fluidized bed for fine crushing and dry magnetic separation, and then enters the fluidized bed process again to complete the reduction. Preferably, in the four setting methods described above, the iron ore powder processed through any one of the steps of crushing, cooling, or dry magnetic separation is either part iron ore powder or all iron ore powder.

[0037] The advantage of placing the fine crushing process before the fluidized bed reduction process is that fine particles have a large specific surface area in the fluidized bed, resulting in high reaction efficiency. It also allows for the use of relatively low fluidizing velocities, reducing the power consumption of fluidization. The disadvantage is that it easily leads to agglomeration and loss of flow; to prevent agglomeration, a relatively low reduction temperature must be used, resulting in reduced reduction efficiency. Conversely, the advantages and disadvantages of fine crushing after the fluidized bed reduction process are exactly the opposite. Therefore, the optimal choice must be determined comprehensively based on the conditions of the iron ore powder, the reducing gas conditions, and the effectiveness of fine crushing and magnetic separation. Considering the raw material conditions and the characteristics of the fine crushing equipment, coarse powder can be coarsely crushed first, preferably to 2-3 mm or less, before entering the fluidized bed, and then finely crushed after exiting the bed, preferably to 100-200 mesh. In summary, in most cases, cooling, fine crushing, and magnetic separation after completing the fluidized bed reduction process is the preferred solution.

[0038] In a further preferred embodiment, when the fine crushing process is arranged after the particles have been reduced, the cooled particles are transported by carrier gas to the fine crushing device for fine crushing, and are separated into high-iron-content particles and low-iron-content particles by magnetic separation. The high-iron-content particles enter the separation bin, and can be directly fed to the electric furnace with DRI powder feeding device for steelmaking in the steelmaking process by pneumatic conveying, or supplied to the converter or electric furnace after briquetting. The low-iron-content particles enter the tailings bin, and can be sent to the tailings furnace for treatment in the tailings treatment process.

[0039] Preferably, the particles are cooled in a cooling-reduction bed or cooling-reduction bed layer in the fluidized bed group, or the particles are cooled in a cooling device outside the fluidized bed; Preferably, the carrier gas is the reducing gas within the fluidized bed assembly, which pneumatically conveys the DRⅠ (Drone I) that has reached the required cooling temperature to the fine crushing chamber for gas-solid separation. A filter bag is installed at the upper outlet of the fine crushing chamber; the reducing gas exits the chamber after filtration, and the purified exhaust gas is collected. The DRⅠ is buffered in the fine crushing chamber and its particles are fed into the fine crushing device through its discharge pipe and feed control valve. Alternatively, a Venturi tube can be installed at the point where the fluidized bed discharge pipe enters the fine crushing chamber, and an impact plate can be installed at an appropriate position opposite its outlet. This utilizes the air pressure of the fluidized bed cooling layer to propel the DRⅠ particles onto the impact plate, achieving a preliminary crushing effect.

[0040] Alternatively, the carrier gas may be a gas that is essentially oxygen-free; more preferably, the gas that is essentially oxygen-free may be selected from at least one of nitrogen or carbon dioxide. When the carrier gas is a gas that is essentially oxygen-free, a blower, a jetting device, and a gas supply and exhaust port need to be added. The discharge pipe of the cooling reduction bed is equipped with an airlock valve for gravity discharge.

[0041] More preferably, the reducing gas can be hydrogen, carbon monoxide-based coal gas, syngas, reformed natural gas, coke oven gas and its reformed gas, other reducing gases, or mixtures thereof; the gas generating device for producing the reducing gas can be a hydrogen electrolyzer, a coal gasifier, a gas reforming device, or, if necessary, a pressurization device, and generally a sufficient reducing gas storage tank. The heating device includes a combustion chamber, a gas source heater, oxygen injection combustion, a plasma heater, etc.

[0042] One of the advantages of this invention is that it places no restrictions on the type of reducing gas. It is suitable for both carbon-based and hydrogen-based smelting, as well as any ratio of carbon to hydrogen. Its significance lies in the fact that this method can be used efficiently from the initial development stage of the transition to hydrogen metallurgy, through the transitional stages of various carbon-to-hydrogen conversion ratios, and all the way to the pure hydrogen stage. This means that production line equipment built using this method will not be rendered obsolete or wasted due to incompatibility with the deepening transformation.

[0043] The present invention also discloses an integrated device for processing tailings, including a delivery system, a smelting system, a slag treatment system and a molten iron system; The material delivery system is used to transport tailings into the smelting system; The smelting system includes a tailings furnace, which consists of a shell, a furnace base, refractory materials, and cooling walls. The furnace body, from bottom to top, comprises the molten iron zone, the slag zone, and the furnace chamber. The furnace zone is equipped with a feed inlet, and the top of the furnace zone is equipped with a gas outlet, an electrode inlet, and a gas sealing device. Outside the furnace, there are electrodes, electrode clamping devices, and power distribution devices. The electrodes enter the tailings furnace from the electrode inlet. Preferably, the sealing gas is nitrogen or carbon dioxide. The slag zone is equipped with a U-shaped injection port and a U-shaped slag outlet, and the U-shaped slag outlet is equipped with a tiltable slag pot; The molten iron section has an iron tapping point; The slag treatment system includes a water spraying device and a water slag storage and transportation device and a water treatment device connected to the water spraying device. The water spraying device is located below the molten slag ladle. The molten iron system includes a molten iron ladle and a conveying device and a casting machine connected to the molten iron ladle for steelmaking, with the molten iron ladle located below the taphole.

[0044] Preferably, the material delivery system is one of the following three forms: Method 1: The feeding system includes a tailings bin, a solvent bin, and a granular carbon bin. The outlets of the tailings bin, solvent bin, and granular carbon bin are all connected to an airlock feeder, which is then connected to the tailings preheating bin, solvent preheating bin, and granular carbon preheating bin, respectively. The outlets of the tailings preheating bin, solvent preheating bin, and granular carbon preheating bin are all connected to a dispensing feeder, which is then connected to a mixing feeder. The mixing feeder is connected to the inlet of the tailings furnace. Preferably, the tailings preheating bin, solvent preheating bin, and granular carbon preheating bin are all provided with a preheating bin air inlet connected to the tailings bin air outlet, and the tailings preheating bin, solvent preheating bin, and granular carbon preheating bin are all provided with a preheating bin air outlet. Method 2: The feeding system includes a tailings bin, a solvent bin, and a granular carbon bin. The outlets of the tailings bin, solvent bin, and granular carbon bin are all connected to a mixing feeder. A counterweight feeder is also connected between the outlets of the tailings bin, solvent bin, and granular carbon bin and the mixing feeder. The outlet of the mixing feeder is connected to the inlet of the combined preheating bin. The outlet of the combined preheating bin is connected to the inlet of the tailings furnace through a screw feeder. Preferably, the combined preheating bin has a preheating bin air inlet connected to the outlet of the tailings bin, and the combined preheating bin has a preheating bin air outlet. Method 3: The feeding system is a tailings injection device. The tailings are injected into the slag pool inside the tailings furnace through the spray gun of the tailings injection device. The spray gun is equipped with a water-cooled sleeve.

[0045] Preferably, the connection method between the mixing feeder in Method 1 or the screw feeder in Method 2 and the inlet of the tailings furnace is as follows: The feed inlet is located on the side wall of the tailings furnace in the furnace zone, and the outlet of the mixing feeder or screw feeder is connected to the feed inlet; Alternatively, the tailings furnace is equipped with a feed pipe, one end of which is connected to the outlet of the mixing feeder or screw feeder, and the other end of which is a feed inlet, which is connected to an annular feeding pipe that is inclined around the motor. Alternatively, the tailings furnace is equipped with a feed pipe, one end of which is connected to the outlet of the mixing feeder or screw feeder, and the other end of which is a feed inlet. The feed inlets are arranged at a suitable height and angle for each electrode, so that the tailings can be thrown to the vicinity of the arc zone released by the electrode. Preferably, the integrated device further includes one or more of the following technical features: The U-shaped slag outlet is a U-shaped liquid-sealed slag outlet; The tailings furnace is also equipped with an oxygen-containing gas inlet; The tailings preheating chamber, solvent preheating chamber, and granular carbon preheating chamber are arranged in a hyperbolic conical shape. The slag bag is insulated and / or equipped with an electric heating device; The furnace zone is equipped with a liquid steel slag inlet at the top.

[0046] Preferably, the integrated device further includes a furnace gas treatment system, which includes furnace gas pipelines, gas distribution devices for various solid material preheating silos, dust removal devices, pressure regulating valve groups, or desulfurization and denitrification devices, or waste heat utilization devices, or induced draft fans.

[0047] The tailings furnace of this invention offers four major advantages: First, it enables 100% utilization of iron in iron ore, solving the problem of unusable residual iron in tailings and steel slag. Second, it utilizes 100% of the components of iron ore other than iron, resolving the solid waste pollution problems associated with tailings dams and steel slag heaps. Third, it allows for the determination of the optimal economic point for fine crushing and magnetic separation operating parameters based on the market's iron-to-steel demand ratio, thus reducing production costs. Fourth, it allows a portion of the molten iron from the tailings furnace to be added to an electric furnace, achieving the carbon requirements for steelmaking cleanly and at low cost.

[0048] The present invention also discloses a method for processing tailings using any of the above-described integrated tailings processing devices, comprising the following steps: Tailings (including DRI tailings and iron ore tailings), solvents (limestone, dolomite, etc.) and particulate carbon (coke powder, carbon powder, etc.) are mixed using the feeding system to form a mixture and fed into the tailings furnace, where they are heated and melted by releasing an electric arc from the electrodes. The tailings are added in the form of powder. The molten slag from the electric furnace and / or converter is fed into the tailings furnace through a U-shaped inlet and melted and mixed with the tailings slag. Preferably, the solvent addition ratio can be adjusted according to the composition of the molten slag to meet the composition requirements for producing qualified water slag after mixing with the tailings slag. After the molten slag in the tailings furnace is discharged through the U-shaped slag outlet, it is mixed in a slag ladle and then discharged into the ladle for water quenching. This process is beneficial to the mixing of slag and liquid components. The resulting water slag can be used as a raw material for cement production. The control of whether or not the tailings furnace discharges slag is achieved by adjusting the furnace pressure through the pressure regulating valve group of the furnace gas treatment system.

[0049] The by-product molten iron produced by the slag melting process in the tailings furnace flows from the tapping port into the molten iron ladle and is cast into block iron or cast iron or directly fed into the steelmaking furnace. Preferably, directly feeding into the steelmaking furnace means directly feeding hot molten iron with temperature into the steelmaking furnace. The furnace gas flows out from the outlet, and its sensible heat and / or chemical heat are used for drying and preheating of tailings, solvents, and carbon particles entering the tailings furnace, and then discharged after purification; or it is input into other systems such as for power generation or fluidized bed reduction.

[0050] Preferably, the method of feeding the mixture into the tailings furnace is selected from any of the following: a) When the mixture is fed into the tailings furnace, it is buried in the solid material pile inside the furnace. The solid material is allowed to enter by applying pressure to the solid material at the feed port. b) The mixture is thrown into the area where the electrodes release the electric arc through the feed pipe extending into the tailings furnace; c) The mixture enters the tailings furnace through the feed pipe and is arranged in the area where the electrode releases the electric arc through the inclined annular distribution pipe that surrounds the electrode. d) When the mixture is fed into the tailings furnace, it is sprayed into the slag pool through the spray gun of the tailings injection device.

[0051] Using the aforementioned tailings treatment method, 100% of the iron contained in the iron ore powder is utilized. Furthermore, 100% of the remaining components are also utilized. Solid pollution from tailings and steel slag is eliminated. Moreover, before environmental protection requirements for industrial applications are fully met, tailings furnace methods, which include environmental costs, cannot compete with tailings disposal methods that do not incur environmental costs. Tailings separated by magnetic separators can be used to make sand, or raw materials suitable for cement rotary kilns can be produced using mature pelletizing and roasting processes.

[0052] The present invention also discloses a direct steelmaking equipment, including the high metallization rate DRI preparation equipment described above, the tailings treatment integrated device described above, the briquetting device, and the converter.

[0053] The briquetting device is used to briquette the high metallization rate DRI powder magnetically separated by the magnetic separation device of the high metallization rate DRI preparation equipment, and then transfer it to the converter for direct steelmaking. The tailings treatment integrated device is used to process low-iron-content material particles magnetically separated by the magnetic separation device of the high metallization rate DRI preparation equipment.

[0054] Both the briquetting device and the converter are existing equipment.

[0055] The present invention also discloses a direct steelmaking method, comprising the following steps: High metallization rate DRI powder preparation process: High metallization rate DRI powder is prepared using any of the above-described methods for preparing high metallization rate DRI. Steelmaking process: The high metallization rate DRI powder is briquetized by a briquetting device and then fed into a converter for steelmaking.

[0056] Preferably, in the high metallization rate DRI powder preparation process, the low iron content material particles selected by the magnetic separation device are processed by any of the tailings treatment methods described above.

[0057] Preferably, in the steelmaking process, the liquid slag produced in the converter is injected into the tailings furnace through the U-shaped inlet of the tailings furnace for the tailings treatment process. In the tailings treatment process, the molten iron produced in the tailings furnace is injected into the converter for use in the steelmaking process.

[0058] In the high metallization rate DRI powder preparation process, the reducing gas enters the tailings treatment process along with the low iron content material particles. After being heated in the tailings furnace, it is returned to the fluidized bed process.

[0059] By adopting the above technical solution, the beneficial effects of the present invention are as follows: The high metallization rate DRI preparation method of the present invention effectively solves the problem of easy agglomeration and flow loss of fine particles in fluidized bed devices, and reduces energy consumption.

[0060] The direct steelmaking method of the present invention reduces carbon emissions and can achieve low-carbon or even zero-carbon steelmaking. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the magnetic separation device for diameter division provided in Embodiment 17; Figure 2 This is a schematic diagram of the deflection magnetic separator provided in Embodiment 18; Figure 3 This is a schematic diagram of the magnetic resonant magnetic separator provided in Embodiment 19; Figure 4 This is a schematic diagram of the integrated tailings processing device provided in Example 13; Figure 5 This is a schematic diagram of the electric arc furnace for melting DRI powder provided in Example 17; Figure 6 This is a schematic diagram of the direct steelmaking method using cooled multi-stage bubbling fluidized bed pure hydrogen magnetic separation provided in Example 17; Figure 7 This is a schematic diagram of the direct steelmaking method using a cooled multi-stage circulating fluidized bed low-carbon deflection magnetic separation provided in Example 18; Figure 8 This is a schematic diagram of the direct steelmaking method using a cooled air-classified multi-layer cone bed pure hydrogen magnetic resonant separation provided in Example 19.

[0062] Among them, 101-cooled multi-stage bubbling fluidized bed group, 102-feed silo, 103-screw feeder, 104-H2 electrolytic cell, 105-storage tank, 106-gas source heater, 107-hydrogen compressor, 108-combustion chamber, 109-integrated device for tailings treatment, 110-heating chamber, 111-oxygen compressor, 112-air separation mechanism, 113-airlock valve, 114-tubular heat exchanger, 115-scrubber, 116-ceramic tube dust collector, 117-circulating compressor, 118-water treatment system, 119-Laval tube, 120-impact plate, 121-pre-selection silo feeder, 122-diameter magnetic separator, 123-electric arc furnace for smelting DRI powder, 124-pneumatic conveying device, 125-bag dust collector, 126-chimney, 127-fine material discharge pipe. 128 - Electric furnace; 129 - Slag ladle; 201-Circulating fluidized bed unit, 202-Grinding mill, 203-Feeding equipment, 204-Deflection magnetic separator, 205-Bulking machine, 206-Converter, 207-Gas generator, 208-Electric heater, 209-Carbon dioxide removal device, 210-Desulfurization device, 211-Raw ore bin, 212-Cyclone dust collector, 213-Blower; 304 - Air separator pipe, 313 - Feed pipe; 401-Air-separated multi-layer cone bed, 402-Magnetic vibration separator, 403-Bulking machine, 404-Bucket elevator, 405-Receiving bin, 406-Weighing bin, 407-Inlet bin, 408-Upper valve, 409-Lower valve; 601-Tailings bin, 602-Solvent bin, 603-Particle carbon bin, 604-Airlock feeder, 607-Tailings preheating bin, 608-Solvent preheating bin, 609-Particle carbon preheating bin, 610-Counterweight feeder, 613-Mixing feeder, 616-U-shaped slag outlet, 617-Iron outlet, 618-Electrode, 619-Air seal device, 620-U-shaped injection port, 621-Slag ladle, 622-Water spray device, 623-Slag storage and transportation device, 628-Iron ladle, 629-Air outlet, 630-Iron zone, 631-Slag zone, 632-Solid stockpile zone, 633-Furnace zone; 122-Magnetic separator for diameter division, 801-Multi-layer vibrating screen for screening, 802-Intermediate trough, 803-Magnetic separator roller, 804-Residual chute, 805-Output chute, 806-Residual bin, 807-Output bin, 808-Dust cover, 809-Magnet, 810-Screw, 811-Screw bevel gear, 812-Control rod bevel gear, 813-Control rod, 814-Bearing seat, 815-Front bin for selection; 901-Scraper, 902-Rope, 903-Fixed pulley, 904-Drive wheel, 905-Enclosed shell, 906-Top air distribution plate, 907-Bottom air distribution plate, 908-Circulating fan, 909-Settling chamber, 910-Air inlet; 1201-Feeder, 1202-Feeding pipe, 1203-Electrode, 1204-Rotating furnace cover, 1205-Fixed furnace cover, 1206-Furnace body, 1207-Furnace body rotating device, 1208-Smoke vent, 1209-Buffer chamber. Detailed Implementation

[0063] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0064] Example 1 A production apparatus for high metallization rate DRI includes a fluidized bed assembly, a fine crushing device, and a magnetic separation device. The fluidized bed unit is equipped with a low-temperature reducing gas inlet and a high-temperature reducing gas inlet; The inlet of the fine crushing device is connected to the fluidized bed group, and / or the outlet of the fine crushing device is connected to the fluidized bed group; The inlet of the magnetic separator is connected to the fluidized bed assembly, and / or the inlet of the magnetic separator is connected to the fine crushing device.

[0065] The fluidized bed assembly is equipped with a low-temperature reducing gas inlet and a high-temperature reducing gas inlet, or a cooling device is also installed outside the fluidized bed assembly.

[0066] The method for preparing high metallization DRI using the apparatus of this embodiment includes the following steps: Fluidized bed process: Iron is produced by reducing iron ore powder with reducing gas in the fluidized bed group; Cooling process: When the fluidized bed group is equipped with a low-temperature reducing gas inlet and a high-temperature reducing gas inlet, the material particles are cooled in the fluidized bed group; when a cooling device is also included, the cooling device is used to cool the material particles obtained by the fluidized bed process reduction. Fine crushing process: using a fine crushing device to finely crush iron ore powder, and / or using a fine crushing device to finely crush the material particles obtained from the fluidized bed process reduction; Magnetic separation process: A magnetic separator is used to perform dry magnetic separation on the material particles after the fluidized bed process and the fine crushing process to obtain DRI powder with a high metallization rate; or a magnetic separator is used in the fluidized bed process to perform dry magnetic separation on the material particles flowing out of the fluidized bed group, and the magnetically separated high iron content material is returned to the fluidized bed process for further reduction, finally obtaining DRI powder with a high metallization rate; the proportion of solid metallic iron in the total mass of DRI powder meets the market requirements for steelmaking slag cost.

[0067] Example 2 A production apparatus for high metallization rate DRI, based on Example 1, wherein the fluidized bed group is a multi-stage bubbling fluidized bed group, preferably 3-6 stages, specifically 3 stages, 4 stages, 5 stages or 6 stages; When preparing DRI powder using the production apparatus of this embodiment, based on Example 1: The reducing gas is introduced from the first-stage fluidized bed. Between adjacent fluidized beds, the reducing gas is discharged from the top of the preceding fluidized bed, enters from the bottom of the following fluidized bed through the reducing gas pipeline, and is discharged from the last fluidized bed. All iron ore powder is added from the last stage fluidized bed, passes through each stage of fluidized bed in sequence, and is discharged from the first stage fluidized bed.

[0068] Example 3 A high metallization rate DRI production apparatus differs from Embodiment 2 in that the last stage fluidized bed is a conical bed with a taper of 3 to 50 degrees on the sidewalls of the bed, specifically 3, 10, 20, 30, 40, or 50 degrees. Preferably, the taper range is 15 to 35 degrees, specifically 15, 25, or 35 degrees. The top of the fluidized bed layer of the last stage fluidized bed is provided with a fine material outlet pipe, and the bottom is provided with a coarse material outlet pipe and a control valve. The difference between using the production apparatus of this embodiment to prepare DRI powder and that of Example 2 is as follows: The iron ore powder first enters the last stage fluidized bed, where it undergoes coarse and fine particle separation. The fine particles are reduced and discharged in the last stage fluidized bed, while the coarse particles pass through each stage of the fluidized bed sequentially and are discharged from the first stage fluidized bed.

[0069] Example 4 A production apparatus for high metallization rate DRI differs from Embodiment 2 in that the subsequent fluidized bed is equipped with an air classifier, which is connected to the final fluidized bed. The difference between using the production apparatus of this embodiment to prepare DRI powder and that of Example 2 is as follows: Iron ore powder first enters the next stage fluidized bed. The air separation mechanism transfers the fine particles in the iron ore powder to the last stage fluidized bed. The fine particles are reduced in the last stage fluidized bed and then discharged. The coarse particles pass through each stage of the fluidized bed sequentially from the next stage fluidized bed and are discharged from the first stage fluidized bed.

[0070] Example 5 A production apparatus for high metallization rate DRI differs from that of Example 2 in that the fluidized bed component is divided into a coarse particle fluidized bed group and a fine particle fluidized bed group, and the fluidized bed group is connected to a sorting device: The difference between using the production apparatus of this embodiment to prepare DRI powder and that of Example 2 is as follows: Before entering the fluidized bed, iron ore powder is first separated into coarse and fine particles by a sorting device, and then enters the coarse particle fluidized bed and the fine particle fluidized bed respectively for reduction.

[0071] Example 6 A production apparatus for high metallization rate DRI differs from that in Example 2 in that the first-stage fluidized bed is a cooling reduction bed, while the other fluidized beds are heating reduction beds.

[0072] The difference between using the production apparatus of this embodiment to prepare DRI powder and that of Example 2 is as follows: High-temperature reducing gas is introduced from the second-stage fluidized bed. Subsequently, the reducing gas between adjacent fluidized beds is discharged from the top of the preceding fluidized bed, enters from the bottom of the following fluidized bed through the reducing gas pipe, and is discharged from the last fluidized bed. Low-temperature reducing gas is introduced from the first-stage fluidized bed, exits from the top of the first-stage fluidized bed, and then enters the second-stage fluidized bed, where it merges with the high-temperature reducing gas. After passing through each stage of heated reducing bed in sequence, it is then discharged.

[0073] Example 7 A high metallization rate DRI production apparatus differs from Example 2 in that the first-stage fluidized bed is a multi-layer bed, with the bottom 1-3 layers being cooling reduction beds. For example, only the bottom layer is a cooling reduction bed, or the bottom and second-bottom layers are cooling reduction beds, or the bottom, second-bottom, and adjacent upper layers are all cooling reduction beds, while the remaining layers are heating reduction beds.

[0074] The difference between using the production apparatus of this embodiment to prepare DRI powder and that of Example 2 is as follows: High-temperature reducing gas enters the bed from the bottom of the gas distribution plate of the heating reducing bed adjacent to the cooling reducing bed, and passes through each heating reducing bed in sequence; low-temperature reducing gas enters the fluidized bed from the bottom of the lowest gas distribution plate of each bed, passes through each cooling reducing bed in sequence, and then merges with the high-temperature reducing gas to enter the heating reducing bed together, and finally exits from the top bed of the first-stage fluidized bed, and then passes through each fluidized bed in sequence, and exits from the last-stage fluidized bed.

[0075] Example 8 A production apparatus for high metallization rate DRI, which differs from any of Examples 2-7 in that it also includes a cyclone dust collector.

[0076] When preparing DRI powder using the production apparatus of this embodiment, the difference from that of Examples 2-7 is that: all or part of the reducing gas discharged from the fluidized bed is collected by a cyclone dust collector before entering the adjacent fluidized bed.

[0077] Example 9 A production apparatus for high metallization rate DRI, based on Example 1, wherein the fluidized bed group is a multi-stage circulating fluidized bed group with 3-7 stages, specifically 3, 4, 5, 6 or 7 stages: between adjacent fluidized beds, reducing gas is discharged from the top of the fluidized bed of the previous stage, enters from the bottom of the fluidized bed of the subsequent stage through a reducing gas pipeline, and is discharged from the last fluidized bed; Iron ore powder is added from the last stage fluidized bed, passes through each stage of fluidized bed in sequence, and is discharged from the first stage fluidized bed.

[0078] Example 10 A production apparatus for high metallization rate DRI differs from that of Example 9 in that the fluidized bed is composed of a coarse particle bed and a fine particle bed, and the fluidized bed is connected to a particle classification device. Before entering the fluidized bed, iron ore powder first enters the particle classification device, which separates it into fine particles and coarse particles according to the design requirements. Then, the particles enter the fine particle bed group or the coarse particle bed group respectively to complete the reduction.

[0079] Example 11 A high metallization rate DRI production apparatus differs from Example 10 in that the multi-stage circulating fluidized bed group is a cooled multi-stage circulating fluidized bed group, the first stage circulating fluidized bed is a cooled reduction bed, and the rest are heated reduction beds: The low-temperature reducing gas enters from the bottom of the first-stage circulating fluidized bed, passes through the first-stage circulating fluidized bed, and then enters the second-stage circulating fluidized bed, where it merges with the high-temperature reducing gas.

[0080] High-temperature gas enters from the bottom of the second-stage circulating fluidized bed, passes through each stage of heating and reduction beds in sequence, and is discharged from the last-stage circulating fluidized bed.

[0081] Example 12 A production apparatus for high metallization rate DRI, based on Example 1, wherein the fluidized bed group is a multi-layer bubbling fluidized bed, or a series or parallel connection of several multi-layer bubbling fluidized beds; In a preferred embodiment, the multi-layer bubbling fluidized bed is an air-classified multi-layer cone bed. More preferably, in the air-classified multi-layer cone bed, the bottom layer or the bottom layer plus the second bottom layer is a cooling reduction bed, and the other layers are heating reduction beds: the finally reduced DRI powder leaves the air-classified multi-layer cone bed from the bottom cooling reduction bed.

[0082] Example 13 An integrated device for processing tailings, such as Figure 4 As shown, it includes a material delivery system, a smelting system, a slag treatment system, and a molten iron system; The material delivery system is used to transport tailings into the smelting system; The material delivery system can be one of the following three forms: The first type: The material delivery system includes a tailings bin 601, a solvent bin 602, and a granular carbon bin 603. The outlet of each bin is connected to an airlock feeder 604, which is then connected to a tailings preheating bin 607, a solvent preheating bin 608, and a granular carbon preheating bin 609. The outlet of each preheating bin is connected to a dispensing feeder 610 for that bin. Each dispensing feeder 610 is connected to a mixing feeder 613 connected to the tailings furnace. The mixing feeder 613 is used to transport materials to the solid stockpile area 632 in the tailings furnace. Each preheating bin has several air inlets at its cone section that are connected to the tailings furnace air outlet 629. Each preheating bin has an air outlet at its top that is connected to the furnace gas purification output system or a subsequent utilization system. The second method is that the feeding system can also combine the three preheating bins into one, that is, the outlets of the tailings bin 601, solvent bin 602 and granular carbon bin 603 are all connected to their respective dispensing feeders 610, each dispensing feeder 610 is connected to the same mixing feeder, the outlet of the mixing feeder is connected to the inlet of the combined preheating bin, and the outlet of the preheating bin is connected to the furnace body of the tailings furnace through a screw feeder. The third type: The feeding system is a tailings injection device, in which tailings are injected into the slag pool inside the tailings furnace through the spray gun of the tailings injection device.

[0083] The smelting system includes a tailings furnace, which consists of a shell, a furnace base, refractory materials, and cooling walls. The furnace body, from bottom to top, comprises the molten iron zone 630, the slag zone 631, and the furnace chamber zone 633. The furnace zone 633 is equipped with a feed inlet, and the top of the furnace zone 633 is equipped with a gas outlet 629, an electrode inlet, and a gas sealing device 619, with nitrogen or carbon dioxide used as the sealing gas. Electrodes 618, electrode clamping devices, and power distribution devices are provided outside the furnace, and electrodes 618 enter the tailings furnace through the electrode inlet; preferably, the top of the furnace zone 633 is also equipped with a liquid steel slag inlet.

[0084] The slag zone 631 is equipped with a U-shaped inlet 620, through which the slag from the electric furnace and / or converter is injected into the slag zone 631. The slag or molten steel slag is then fed into the tailings furnace to melt and mix with the tailings slag. If necessary, the solvent ratio can be adjusted during the steelmaking process to ensure that the mixture meets the composition requirements for producing qualified slag after mixing with the tailings slag. The slag zone 631 is also equipped with a U-shaped slag outlet 616. Whether or not slag is discharged from the tailings furnace is controlled by adjusting the furnace pressure through the pressure regulating valve group of the furnace gas treatment system. A tiltable slag ladle 621 is provided at the U-shaped slag outlet 616, and the slag ladle 621 is equipped with insulation and / or an electric heating device.

[0085] Iron tapping point 617 is located in iron molten metal zone 630.

[0086] The slag treatment system is located below the slag ladle 621. After the slag ladle 621 is filled with slag, it is poured out by tilting for water quenching. This process facilitates the mixing of the slag liquid components. The slag treatment system includes a water spraying device 622 located below the slag ladle 621, and a water slag storage and transportation device 623 and a water treatment device connected in sequence to the water spraying device 622.

[0087] The molten iron system includes a molten iron ladle 628 located below the taphole 617, and a conveying device for steelmaking and a casting machine connected in sequence to the molten iron ladle 628.

[0088] Maintenance holes are provided on the tailings furnace body to facilitate personnel entering the furnace for inspection and maintenance.

[0089] Example 14 An integrated device for processing tailings, such as Figure 4 As shown, based on Example 13, The U-shaped slag outlet 616 is a "U" shaped liquid seal slag outlet; The tailings furnace is also equipped with an oxygen-containing gas inlet; The tailings preheating chamber 607, the solvent preheating chamber 608, and the granular carbon preheating chamber 609 are arranged in a hyperbolic conical shape.

[0090] Meanwhile, in the integrated device, the connection method between the mixing feeder in the first method and the screw feeder in the second method and the feed inlet of the tailings furnace is one of the following: I. The feed inlet is located on the side wall of the tailings furnace in the furnace zone, and the outlet of the mixing feeder or screw feeder is connected to the feed inlet; II. The tailings furnace is equipped with a feed pipe. One end of the feed pipe is connected to the outlet of the mixing feeder or the screw feeder, and the other end of the feed pipe is a feed inlet. The feed inlet is connected to an annular material distribution pipe that is inclined around the motor. III. The tailings furnace is equipped with a feed pipe. One end of the feed pipe is connected to the outlet of the mixing feeder or the screw feeder, and the other end of the feed pipe is the inlet. The inlet is arranged at a suitable height and angle for each electrode so that the tailings can be thrown to the vicinity of the arc zone released by the electrode.

[0091] Example 15 A method for processing tailings, using the integrated apparatus provided in Example 13 or Example 14: Tailings, solvents (limestone, dolomite, etc.) and granular carbon (coke powder, carbon powder, etc.) are mixed to form a mixture, which is then fed into a tailings furnace and heated and melted by releasing an electric arc from the electrodes. The tailings are added in the form of powder. The method of feeding the mixture into the tailings furnace is selected from any of the following: When the connection method between the mixing feeder or screw feeder in Example 14 and the inlet of the tailings furnace is I: a) When the mixture is fed into the tailings furnace, it is buried in the solid material pile inside the furnace. The solid material is allowed to enter by applying pressure to the solid material at the feed port. When the connection method between the mixing feeder or screw feeder in Example 14 and the inlet of the tailings furnace is III: b) The mixture is thrown into the area where the electrodes release the electric arc through the feed pipe extending into the tailings furnace; When the connection method between the mixing feeder or screw feeder in Example 14 and the inlet of the tailings furnace is II: c) The mixture enters the tailings furnace through the feed pipe and is arranged in the area where the electrode releases the electric arc through the inclined annular distribution pipe that surrounds the electrode. When the material delivery system in Example 13 is a tailings injection device: d) When the mixture is fed into the tailings furnace, it is sprayed into the slag pool through the spray gun of the tailings injection device.

[0092] The molten slag from the electric furnace and / or converter is fed into the tailings furnace through a U-shaped inlet to melt and mix with the tailings slag. After the slag in the tailings furnace is discharged from the furnace through the U-shaped slag outlet, it is mixed in a slag ladle and then discharged from the ladle for slag treatment. The by-product molten iron produced during the slag melting process in the tailings furnace flows from the tapping port into the molten iron ladle and is cast into block iron or foundry iron or directly sent into the steelmaking furnace. The furnace gas flows out from the outlet 629, and its sensible heat and / or chemical heat are used for drying and preheating of the tailings, solvents, and carbon particles entering the tailings furnace.

[0093] Example 16 This embodiment discloses a direct steelmaking method, including the following steps: High metallization rate DRI powder preparation process: High metallization rate DRI powder is prepared using the preparation methods of high metallization rate DRI in Examples 1 to 12 above; the magnetic separation device is existing equipment.

[0094] Steelmaking process: The high metallization rate DRI powder is briquetized by a briquetting device and then fed into a converter for steelmaking. The briquetting device and converter are existing equipment.

[0095] In the high metallization rate DRI powder preparation process, the low iron content material particles selected by the magnetic separation device are processed by the tailings treatment method described in Example 15.

[0096] In the steelmaking process, the liquid slag produced in the converter is injected into the tailings furnace through the U-shaped inlet 620 for the tailings treatment process. In the tailings treatment process, the molten iron produced in the tailings furnace is injected into the converter for use in the steelmaking process.

[0097] In the high metallization rate DRI powder preparation process, the reducing gas enters the tailings treatment process along with the low iron content material particles. After being heated in the tailings furnace, it is returned to the fluidized bed process.

[0098] Example 17 To facilitate a clearer understanding of the technical solution of the present invention by those skilled in the art, this embodiment discloses a detailed direct steelmaking method. The direct steelmaking method of this embodiment adopts a cooling multi-stage bubbling fluidized bed pure hydrogen magnetic separation method, that is, using a cooling multi-stage bubbling fluidized bed group for reduction + pure hydrogen reducing gas + magnetic separation using a magnetic separation device.

[0099] like Figure 6 As shown, low-grade Brazilian iron ore powder containing 60% iron is fed into a cooling multi-stage bubbling fluidized bed group 101 via a feed hopper 102 and a screw feeder 103. The bed group consists of five fluidized beds. Figure 6 From right to left, the fluidized beds are arranged in five stages: first, second, third, fourth, and fifth (shown as R1, R2, R3, R4, and R5 in the diagram). Material with a particle size ≤0.3mm is pre-loaded into the fifth fluidized bed through the inspection port, while material with a particle size >0.3mm is pre-loaded into the second, third, and fourth fluidized beds. Hydrogen produced by the H2 electrolyzer 104 is stored in storage tank 105 via hydrogen compressor 107. Hydrogen exiting storage tank 105 then enters the gas source heater 106. Combustion chamber 108 is introduced with some oxygen produced during the electrolysis process. It is used to burn a mixture of recycled hot hydrogen that has not been dehydrated and tail gas from tailings furnace 109. The high-temperature exhaust gas from the combustion is heated to a higher temperature by gas source heater 106. Then, a small amount of oxygen is added by oxygen compressor 111 and the hydrogen is heated by combustion in heating chamber 110. Finally, the hydrogen is heated to 1050 degrees and enters the cooled multi-stage bubbling fluidized bed group 101 from the fourth fluidized bed gas distribution chamber.

[0100] When the fluidized bed reaches the bubbling fluidization state and the metallization rate of large particles reaches 95%, iron ore powder can be continuously fed into the fourth-stage fluidized bed according to the design flow rate. After passing through the air separation mechanism 112 located in the fourth-stage fluidized bed, fine particles ≤0.3 mm enter the fifth-stage fluidized bed through the air separation pipe 304. The remaining large particles enter the fourth-stage fluidized bed through the feed pipe 313, undergo fluidization and reduction in the fourth-stage bed, and then enter the third-stage fluidized bed through the discharge pipe of the fourth-stage fluidized bed and the airlock valve 113. The same process is then repeated in the second-stage and first-stage fluidized beds.

[0101] The first-stage fluidized bed is a cooled reduction bed. Unheated, room-temperature hydrogen gas is blown in from the bottom gas distribution chamber through the gas distribution plate at half the flow rate of heated hydrogen gas. Hydrogen gas at 1050 degrees Celsius enters from the gas distribution chamber of the second-stage fluidized bed, mixing with cooled hydrogen gas from the first-stage fluidized bed after cooling DRI powder, resulting in a temperature of 900 degrees Celsius before entering the second-stage fluidized bed. It then passes through a built-in cyclone dust collector at the top and exits from the top of the second-stage fluidized bed, entering the gas distribution chamber of the third-stage fluidized bed through a pipe. After passing through the gas distribution plate, the bed, and the built-in cyclone dust collector, it exits, and similarly enters the fourth and fifth-stage fluidized beds. The hydrogen gas undergoes a high-temperature reduction reaction with iron ore at each fluidized bed layer, producing water which enters the tail gas as steam.

[0102] The exhaust gas, ultimately discharged from the top of the fifth-stage fluidized bed via a built-in cyclone dust collector, has a very small portion returning to the combustion chamber 108 as fuel or mixed with the exhaust gas from the tail gas furnace to burn and heat hydrogen, or burned with oxygen and then mixed with the tail gas furnace exhaust gas to heat hydrogen. The vast majority enters the exhaust gas treatment system, undergoing fine dust removal by the ceramic tube dust collector 116, cooling on the hot side of the tubular heat exchanger 114, dehydrating in the scrubber 115, pressurizing by the circulating compressor 117, and then reheating on the cold side of the tubular heat exchanger 114 before returning to the gas source heater 106 at the front of the fluidized bed for recycling. The water discharged from the scrubber 115 is returned to the electrolytic cell 104 for recycling after passing through the water treatment system 118. The gas discharged from the gas source heater 106 is treated by the bag filter 125 and then discharged through the chimney 126.

[0103] The reduction temperature of the fifth-stage fluidized bed is 620~650 degrees Celsius to avoid fine particles from agglomerating and losing flow.

[0104] The DRl powder that has undergone reduction in the second-stage fluidized bed has a temperature of 860 degrees Celsius, and its temperature after cooling in the first-stage fluidized bed is 120 degrees Celsius.

[0105] The airflow reaches supersonic speed through the Laval tube 119 installed on the discharge pipe of the first-stage cooling fluidized bed, causing the ejected particles to impact the impact plate 120 in the pre-selection chamber. The flow rate is controlled by a valve at the inlet of the discharge pipe. After the crushed particles fall into the pre-selection chamber 815, the fine particles DRⅠ that have been reduced by the fifth-stage fluidized bed also enter the pre-selection chamber 815 through the fine material discharge pipe 127. The particles are then distributed onto the multi-layer vibrating screen 801 of the sizing magnetic separator 122 by the pre-selection chamber feeder 121 located at the discharge port of the pre-selection chamber 815. The specific structure of the sizing magnetic separator 122 is as follows... Figure 1 As shown, it should be noted that the magnetic separation device 122 is not existing technology. The vibrating screen 801 has four layers, dividing the particles into five size groups: ≥1.5~1.0~0.5~0.2~0mm. Magnetic separation is performed on five magnetic separation rollers 803 arranged through an intermediate chute 802. Approximately 80% of the separated particles enter the separation chamber 807, with a grade of approximately 90%, while the remaining 20% ​​enters the residual separation chamber 806, with a grade of approximately 47%. The hydrogen gas entering the pre-separation chamber 815 is at approximately 100 degrees Celsius. After being filtered by filter bags, the hydrogen gas exiting the pre-separation chamber 815 is piped into the purified and recycled hydrogen gas.

[0106] The pneumatic conveying device 124 located at the lower part of the selection bin 807 transports the selected DR1 powder to the buffer bin 1209 at the top of the DRⅠ powder melting electric arc furnace 123. The specific structure of the DRⅠ powder melting electric arc furnace 123 is as follows: Figure 5 As shown, it should be noted that this electric arc furnace 123 is not existing technology. Through three spiral feeders 1201 and three feed pipes 1202, DRⅠ powder can be delivered to the lower arc zone of the three electrodes 1203. The rotating furnace cover 1204 is opened. Scrap steel, auxiliary materials, and molten iron from the tailings furnace 109 are added. After the cover is closed, the electrodes 1203 are lowered for smelting. Once a slag surface has formed at the lower end of the electrodes 1203, DRⅠ powder is continuously added to continue smelting. During the above process, slag-forming agents and ferroalloys required for the steel grade also need to be added. After steelmaking is completed, the steel is tapped, and then the slag is removed. If no scrap steel is added during the smelting process, the slag liquid can be directly water-quenched by tempering during steelmaking to meet the conditions for direct water quenching. If it is mixed with scrap steel for smelting, the slag liquid can be treated in accordance with existing technology. Preferably, the slag liquid is stored in steel slag tank 129 and transported to integrated tailings treatment device 109. After being mixed and modified by integrated tailings treatment device 109, water slag is produced.

[0107] The remaining material in the tailings bin 806 is the tailings. It is fed into the tailings bin 601 of the integrated tailings processing device 109 (specifically, the integrated tailings processing device described in Example 13) via a pneumatic conveying device 124 at the bottom of the tailings bin 806. The tailings then enter the tailings furnace via a dispensing feeder 610 and a mixing feeder 613 under the tailings bin 601, continuously pushing the tailings into the arc zone of the tailings furnace electrode 618. Simultaneously, appropriate amounts of solvent (such as lime) and carbon powder are added through the solvent bin 602 and granular carbon bin 603 to maintain the carbon content of the produced molten iron and the water-quenched slag properties in accordance with national standards. The produced molten iron is stored in an iron ladle 628 and then transported to the DRI powder smelting electric arc furnace 123.

[0108] The magnetic separator 122 used in this embodiment is as follows: Figure 1 As shown, a multi-layer vibrating screen screening device 801 is included. Intermediate material troughs 802 for receiving materials of different particle sizes are provided at the discharge port of each layer of vibrating screen and below the bottom layer of vibrating screen. A magnetic separator roller 803 is provided at the outlet of each intermediate material trough 802. The magnetic separator roller 803 includes a magnet 809 and a cylinder body. The magnet 809 is located inside the cylinder body. During operation, the position of the magnet 809 is fixed, while the cylinder body rotates. The magnet 809 inside the cylinder body can be an electromagnet or a permanent magnet. When a permanent magnet is used, the magnet 809 is divided into multiple pieces along the circumference of the cylinder body and arranged at a certain distance from the surface of the cylinder body. A magnetic separation spacing adjustment mechanism can be provided.

[0109] The magnetic separation spacing adjustment mechanism includes a frame, a control rod 813, and multiple screws 810. The frame is equipped with multiple bearing seats 814, and each screw 810 is rotatably mounted within one of the bearing seats 814. The axis of each screw 810 is parallel to the radial direction of the magnetic separation roller 803. The control rod 813 coincides with the axis of the roller body, meaning each screw 810 is perpendicular to the control rod 813. One end of each screw 810 is equipped with a screw bevel gear 811, and the control rod 813 is equipped with a control rod bevel gear 812. The control rod bevel gear 812 meshes with the screw bevel gear 811. It can only be driven to rotate by the screw bevel gear 811 and cannot move radially or circumferentially; each magnet 809 has a threaded hole with internal thread, that is, the magnet 809 is equivalent to a nut. The magnet 809 is slidably connected in the guide groove set parallel to the screw 810, and can only move radially and cannot rotate. The threaded hole is connected to the other end of the screw by thread engagement; by rotating the control rod 813, the power can be transmitted to the screw 810 through the control rod bevel gear 812 and the screw bevel gear 811, driving the screw 810 to rotate, thereby realizing the adjustment of the distance between the magnet 809 and the surface of the magnetic separation roller 803.

[0110] At the selection drop point of each magnetic separator roller 803, a selection chute 805 is provided, connected to the selection bin 807 below it. At the selection drop point, a selection residue chute 804 is provided, connected to the selection residue bin 806 below it. The multi-layer vibrating screen screening device 801 and the intermediate material trough 802 are covered with dust covers 808.

[0111] The electric arc furnace 123 used in this embodiment for melting DRI powder is as follows: Figure 5 As shown, it includes a furnace body 1206, a furnace body rotating device 1207, a DRI powder feeding device, a furnace cover, a furnace cover driving device, an electrode 1203, an electrode driving device, an electrode power supply device, a flue gas vent 1208, a flue gas purification output system, an auxiliary material pipe, and an auxiliary material feeding device. The furnace body rotation device 1207 is connected to the furnace body 1206 and is used to control the tilting of the furnace body 1206 to achieve operations such as steel tapping and slag removal. The furnace cover drive device is connected to the furnace cover and is used to drive the furnace cover to rotate, realizing the opening and closing of the furnace cover to meet the needs of operations such as charging and maintenance. The electrode 1203 extends from the furnace cover into the furnace body 1206. The electrode power supply device and the electrode drive device are both connected to the electrode 1203. The electrode power supply device is used to supply power to the electrode 1203, and the electrode drive device is used to drive the electrode 1203 to rise and fall. The flue gas vent 1208 is set on the furnace cover and is connected to the flue gas purification and output system for purifying the flue gas discharged from the electric furnace before discharge. The auxiliary material pipe is connected to the auxiliary material feeding device. The auxiliary material pipe can be set on the furnace body 1206 for adding auxiliary materials, such as slag-forming agents, into the furnace. The specific structure of this part can be set with reference to the existing electric furnace, so it will not be described in detail.

[0112] The DRI feeding device includes a buffer silo 1209, a feeder 1201, and a feed pipe 1202. The buffer silo 1209 is equipped with a dust removal system. The feeder 1201 is connected to the lower outlet of the buffer silo 1209, and the upper end of the feed pipe 1202 is connected to the outlet of the feeder 1201. The DRI powder feeding device is equipped with a nitrogen or carbon dioxide priming protection system.

[0113] In the electric arc furnace for steelmaking, the connection relationship between the feed pipe 1202 and the furnace cover is as follows: a) The furnace cover is divided into a fixed furnace cover 1205 and a rotating furnace cover 1204. The rotating furnace cover 1204 is driven to rotate by a furnace cover driving device.

[0114] The feed pipe 1202 is divided into branches corresponding to the number of electrodes, and is inserted into the furnace from the fixed furnace cover 1205. The height and angle of the discharge port of each branch feed pipe 1202 are such that the powder being fed falls near the corresponding electrode arc area. Figure 5 As shown; b) The furnace cover is a rotating furnace cover. The feed pipe 1202 is provided with several branch outlets. Each branch feed pipe is divided into upper and lower sections. The lower section is fixed on the rotating furnace cover and passes through the rotating furnace cover and extends into the furnace body. Preferably, the lower section is connected to a material distribution pipe that is inclined around the corresponding electrode. Multiple discharge ports are opened below the annular material distribution pipe. The upper opening of the upper section is rotatably connected to the branch outlet of the feed pipe. The upper section can swing. When the rotating furnace cover is on the furnace body, the swing of the upper section can make its lower opening align with the upper opening of the corresponding branch feed pipe lower section, so that the axes of the two openings coincide.

[0115] The steelmaking method of the electric arc furnace using this scheme is as follows: DRI powder is supplied into the electric furnace, allowing the continuously added powder to enter the vicinity of the electric arc zone, thereby achieving efficient melting upon entry into the furnace. Specifically, the DRI powder is transported to the electric arc zone of the electrode through a buffer hopper 1209, a feeder 1201, and a feed pipe 1202. The flow rate of the DRI powder is controlled to match the melting capacity of the electrode 1203. A continuous feeding method is adopted, ensuring that the continuously added DRI powder first enters the electric arc zone to achieve efficient melting. The process is protected by nitrogen, carbon dioxide, or waste gas to prevent oxidation. The advantages of this steelmaking method are that it not only solves the problem of ice formation during powder melting but also improves smelting efficiency, while seamlessly integrating with traditional scrap steel-using steelmaking processes.

[0116] Example 18 The direct steelmaking method in this embodiment is a direct steelmaking method using a cooled multi-stage circulating fluidized bed with low-carbon deflection magnetic separation, that is, using a cooled multi-stage circulating fluidized bed group for reduction + low-carbon reducing gas + deflection magnetic separation device for magnetic separation.

[0117] like Figure 7 As shown, there are only five differences from Example 17: First, the fluidized bed group selected is four conventional circulating fluidized bed groups 201. Its operation process is the same as that of conventional circulating fluidized beds, so it will not be repeated here. The only difference is that the operating temperature of the first-stage fluidized bed does not exceed 700 degrees. The second, third and fourth-stage fluidized beds are appropriately supplemented with heat reducing gas so that the reduction temperature of the second and third beds is between 550 and 700 degrees, and the fourth bed is around 500 degrees.

[0118] Secondly, the fine crushing process is placed before the fluidized reduction process. The raw ore bin 211 sends the coarse ore powder to the grinding mill 202. The hot air obtained by the blower 213 and the heat exchanger 114 enters the grinding mill 202 and is used to transport the fine ore powder ground by the grinding mill 202 to the cyclone dust collector 212. The powder is then fed into the fourth-stage fluidized bed through the feeding device 203, with a particle size of 100~200 mesh.

[0119] Thirdly, magnetic separation is placed between the fourth and third fluidized beds, using an offset magnetic separator 204. It should be noted that the offset magnetic separator 204 is not existing technology; it eliminates the need for the pre-separation chamber 815, replacing its outlet with the discharge pipe of the cyclone dust collector from the fourth fluidized bed. The magnetic separation temperature is 400-500 degrees Celsius. The DRI powder from the first fluidized bed is directly conveyed hot to the DRI powder melting electric arc furnace 123 via a pneumatic conveying device 124, or pressed into briquettes by the briquetting machine 205 and then sent to the converter 206.

[0120] Fourth, the reducing gas generating device selected is gasifier 207. If the temperature of gasifier 207 is insufficient, electric heater 208 can be used to raise the temperature, or a small amount of oxygen can be injected for combustion to raise the temperature.

[0121] Fifth, the gas purification system is equipped with a carbon dioxide removal device 209 and a desulfurization device 210. The exhaust gas discharged from the cyclone dust collector of the fourth-stage fluidized bed is finely dusted by the ceramic tube dust collector 116. After being cooled on the hot side of the tubular heat exchanger 114, the exhaust gas enters the scrubber 115 for dehydration, the desulfurization device 210 for desulfurization, and the carbon dioxide removal device 209 for CO2 removal. After being pressurized by the circulating compressor 117, it enters the tubular heat exchanger 114 for heating on the cold side and then returns to the electric heater 208 at the front of the fluidized bed group for recycling.

[0122] Everything else is the same as in Example 17. It should be noted that, since the remaining iron ore powder has not yet begun metallization, the tailings furnace of the integrated tailings processing device 109 needs to have more carbon or coal powder added, increasing the gas volume in the tailings furnace so that it can be combined with the gas source from the gas generator and enter the fluidized bed group. Therefore, the tailings furnace design must meet the requirements for high-pressure operation.

[0123] The deflection magnetic separator in this embodiment is as follows: Figure 2As shown, it includes a pre-selection chamber 815, a magnet 809, a selection chamber 807, and a residual selection chamber 806. The discharge port of the pre-selection chamber 815 and the inlet of the residual selection chamber 806 are arranged vertically correspondingly. The magnet 809 is located between the pre-selection chamber 815 and the residual selection chamber 806. The magnetic lines of force generated by the magnet 809 are generally as perpendicular as possible to the vertical line of the discharge port of the pre-selection chamber 815, and point towards or away from the magnet. The inlet of the selection chamber 807 is close to the inlet of the residual selection chamber 806 and is arranged on the same side as the magnet. The pre-selection chamber 815, which accepts different particle size groups, has several closely spaced components, and the inlets of the separation chamber 807 are all located on the same horizontal plane. The magnets are electromagnets and / or permanent magnets. A magnet cleaning device is provided on the magnet 809, located on the side facing the particles to be magnetically separated. The deflection magnetic separator also includes a pulley group consisting of a fixed pulley 903 and a drive wheel 904. A rope 902 is provided on the pulley group. In this embodiment, the magnet cleaning device is a scraper 901, which is mounted on the rope 902 and driven by the drive wheel 904 for dust removal. The deflection magnetic separator also includes a closed housing 905, which at least includes the area from the bottom outlet of the pre-selection chamber 815 to the inlet of the residual selection chamber 806 and the separation chamber 807. The magnets 809 are enclosed inside or outside the housing. The top of the closed housing 905 has an air inlet and a top air equalization plate 906, and the bottom has an air outlet and a bottom air equalization plate 907. The sealed housing 905 has a settling chamber 909, an air inlet 910, and a circulating fan 908 connected sequentially from bottom to top. The circulating fan 908 is connected to the air inlet at the top of the sealed housing 905, and the air outlet at the bottom of the sealed housing 905 is connected to the settling chamber 909. This device is used to apply a downward airflow to the particles to be magnetically separated during their fall to counteract air resistance.

[0124] The magnetic separation method using the aforementioned deflection magnetic separator is as follows: the particles to be magnetically separated are placed in a free-fall state; a magnet is placed on one side along the falling path, with the magnetic field lines generally horizontal and pointing away from the magnet; the particles to be magnetically separated are sieved according to their magnetization strength under the action of magnetic force. At the same time, a downward airflow is applied during the falling process of the particles to be magnetically separated to counteract air resistance.

[0125] Example 19 A direct steelmaking method employing a cooled air-classified multi-layer conical bed for pure hydrogen magnetic separation involves using a cooled air-classified multi-layer conical bed (a multi-layer conical fluidized bed containing an air-classification mechanism and a cooling bed) + pure hydrogen reducing gas + magnetic separation using a magnetic separation device.

[0126] like Figure 8 As shown, the differences from Example 17 are: First, the fluidized bed group uses a multi-layer conical air classifier 401 with 5 layers. The bottom fluidized bed is a cooling bed. Iron ore powder enters the multi-layer conical air classifier 401 from the second-to-top fluidized bed. Fine particles enter the top fluidized bed for reduction. The reduced fine particles are discharged from the multi-layer conical air classifier 401. Coarse particles are reduced from the second-to-top fluidized bed and then enter the lower fluidized bed layers through the feed pipe for further reduction. Finally, they are discharged from the bottom fluidized bed. Both coarse and fine particles discharged from the multi-layer conical air classifier 401 pass through the Laval pipe 119, which makes the airflow supersonic. The ejected particles impact the impact plate 120 in the pre-selection chamber. The flow rate is controlled by the valve at the inlet of the discharge pipe. The crushed particles fall into the pre-selection chamber.

[0127] Secondly, a magnetic separation device 402 with vibration type is selected below the front silo 815 for magnetic separation. It should be noted that the magnetic separation device 402 is not existing technology. The distance between the electromagnets on both sides is adjustable from 50 to 200 mm, the width is 1000 mm, the total height is 3000 mm, and it is divided into ten magnetic segments. The temperature of DRⅠ powder during magnetic separation is around 700 degrees Celsius. The separated portion enters the separation silo 807, then enters the briquetting machine 403. After briquetting, it is sent to the receiving silo 405 of the DRⅠ hot briquetting feeder for the electric furnace via the bucket elevator 404, then enters the weighing silo 406 through the upper valve 408, and then enters the electric furnace 128 through the inlet silo via the lower valve 409. A conventional electric furnace can be selected. Nitrogen protection is used throughout the process to prevent oxidation. Alternatively, it can be supplied to a converter for steelmaking.

[0128] The rest are the same as in Example 17.

[0129] The magnetic separation device of this embodiment, such as Figure 3 As shown, it includes a pre-selection chamber 815, a magnetic vibration separator, a selection chamber, and a remaining selection chamber. The magnetic vibration separator is located below the discharge port of the pre-selection chamber 815. The separator includes two magnetic field components, each composed of electromagnets 809 arranged vertically. The two magnetic field components are symmetrically arranged on either side of the vertical line descending from the discharge port of the pre-selection chamber 815. Two separation chamber inlets are located below the two magnetic field components, and the residual separation chamber inlet is located between the two separation chamber inlets. The electromagnets in both magnetic field components are vertically aligned. The distance between the two magnetic field components is adjustable.

[0130] The magnetic separation method using the aforementioned magnetic vibration separator is as follows: The particles to be separated are subjected to free fall, forming a falling material flow. Electromagnets that can be opened and closed are arranged at equal heights on both sides of the falling material flow. The electromagnets at the same height on both sides are opened and closed alternately. Adjacent electromagnets on the same side are also opened and closed alternately. The alternating magnetic fields on both sides are used to separate strongly magnetized particles from weakly magnetized particles. During magnetic separation, the principle is that if one side of a segment at the same height is energized, the other side is de-energized, and vice versa; from top to bottom, if adjacent segments are energized, the current segment is de-energized, and vice versa; the energizing cycle should be adjusted to achieve a higher magnetic separation efficiency. The advantages of magnetic vibration separation are twofold: firstly, it involves alternating magnetic separation on both sides of the falling material flow; secondly, it helps to eliminate agglomeration and improve magnetic separation efficiency.

Claims

1. A production apparatus of high metallization rate DRI, characterized by, Includes fluidized bed assembly, fine crushing unit, and magnetic separation unit. The inlet of the fine crushing device is connected to the fluidized bed group, and / or the outlet of the fine crushing device is connected to the fluidized bed group; The inlet of the magnetic separator is connected to the fluidized bed assembly, and / or the inlet of the magnetic separator is connected to the fine crushing device; The fluidized bed assembly is equipped with a low-temperature reducing gas inlet and a high-temperature reducing gas inlet, or the production equipment for the high metallization rate DRI also includes a cooling device.

2. A method for producing high metallization DRI using the production facility for high metallization DRI according to claim 1, characterized by, The process includes the following steps: Fluidized bed process: Iron is produced by reducing iron ore powder with reducing gas in the fluidized bed group; Cooling process: When the fluidized bed group is equipped with a low-temperature reducing gas inlet and a high-temperature reducing gas inlet, the material particles are cooled in the fluidized bed group; when the production equipment also includes a cooling device, the cooling device is used to cool the material particles obtained by the fluidized bed process reduction. Fine crushing process: using a fine crushing device to finely crush iron ore powder, and / or using a fine crushing device to finely crush the material particles obtained from the fluidized bed process reduction; Magnetic separation process: A magnetic separation device is used to perform dry magnetic separation on the material particles after the fluidized bed process and the fine crushing process to obtain DRI powder with high metallization rate; or a magnetic separation device is used in the fluidized bed process to perform dry magnetic separation on the material particles flowing out of the fluidized bed group, and the high iron content material separated by magnetic separation is returned to the fluidized bed process for further reduction, and finally DRI powder with high metallization rate is obtained. The proportion of solid metallic iron in DRI powder meets market requirements for the cost ratio of steelmaking slag.

3. The method of claim 2, wherein the high metallization rate DRI is produced by the steps of: The fluidized bed group is a multi-stage bubbling fluidized bed group, preferably with 3 to 6 stages. Between adjacent fluidized beds, reducing gas is discharged from the top of the preceding fluidized bed, enters from the bottom of the following fluidized bed through a reducing gas pipeline, and is discharged from the last fluidized bed. The fluidized bed group and the corresponding fluidized bed process are selected from one of the following forms: a) All iron ore powder is added from the last stage fluidized bed, passes through each stage of fluidized bed in sequence, and is discharged from the first stage fluidized bed; b) The last stage fluidized bed is a conical bed with a taper of 3 to 50 degrees on the sidewalls, preferably 15 to 35 degrees. The top of the fluidized bed layer of the last stage fluidized bed is equipped with a fine material outlet pipe, and the bottom is equipped with a coarse material outlet pipe and a control valve. The iron ore powder first enters the last stage fluidized bed, where it undergoes coarse and fine particle separation. The fine particles are reduced and discharged in the last stage fluidized bed, while the coarse particles pass through each stage of the fluidized bed sequentially and are discharged from the first stage fluidized bed. c) The subsequent fluidized bed is equipped with an air separation mechanism, which is connected to the last fluidized bed: Iron ore powder first enters the next stage fluidized bed. The air separation mechanism transfers the fine particles in the iron ore powder to the last stage fluidized bed. The fine particles are reduced in the last stage fluidized bed and then discharged. Coarse particles pass through each stage of the fluidized bed sequentially from the next stage fluidized bed and are discharged from the first stage fluidized bed. d) The fluidized bed group is divided into a coarse particle fluidized bed group and a fine particle fluidized bed group, and the fluidized bed group is connected to the sorting device: Before entering the fluidized bed, iron ore powder is first separated into coarse and fine particles by a sorting device, and then enters the coarse particle fluidized bed and the fine particle fluidized bed respectively for reduction.

4. The method of claim 3, wherein the high metallization rate DRI is produced by the steps of: The fluidized bed assembly also includes the following technical features: e) The fluidized bed group is a cooled multi-stage bubbling fluidized bed group: The first-stage fluidized bed of the cooling multi-stage bubbling fluidized bed group is a cooling reduction bed, and the other fluidized beds are heating reduction beds; Alternatively, the next stage fluidized bed in the cooling multi-stage bubbling fluidized bed group is a cooling reduction bed, and the other fluidized beds are heating reduction beds. The material outlet of the next stage fluidized bed is connected to the next secondary fluidized bed through the magnetic separator. Alternatively, the first-stage fluidized bed of the cooling multi-stage bubbling fluidized bed group is a multi-layer bed, with the bottom 1 to 3 layers of the first-stage fluidized bed being cooling reduction beds and the remaining layers being heating reduction beds; High-temperature reducing gas enters the first-stage fluidized bed from the bottom of the gas distribution plate of the heating reducing bed adjacent to the cooling reducing bed, and passes through each heating reducing bed in sequence; low-temperature reducing gas enters the first-stage fluidized bed from the bottom of the lowest gas distribution plate, passes through each cooling reducing bed in sequence, and then merges with the high-temperature reducing gas to enter the heating reducing bed together, and finally exits from the top layer of the first-stage fluidized bed.

5. The method for preparing high metallization rate DRI as described in claim 3, characterized in that, When the fluidized bed group is in the form of a)-d), the cooling of the reduced DRI powder is completed by a cooling device located outside the fluidized bed group. Preferably, when the fluidized bed group is in the form of d), after the fine particles are discharged from the fine particle fluidized bed group, they enter the coarse particle fluidized bed group for further reduction, and then enter the cooling device together with the coarse particles, either partially or completely.

6. The method for preparing high metallization rate DRI as described in claim 4, characterized in that, When the fluidized bed group is a combination of d) and e), the first-stage fluidized bed is a coarse-particle fluidized bed group: After being discharged from the fine particle fluidized bed, the fine particles enter the first-stage fluidized bed together with the coarse particles, either entirely or partially. Alternatively, after being discharged from the fine particle fluidized bed, the fine particles enter the heating and reducing bed of the first-stage fluidized bed for further reduction, and then, together with the coarse particles, enter the cooling and reducing bed of the first-stage fluidized bed in whole or in part.

7. The method of claim 3, wherein the high metallization rate DRI is produced by the steps of: The reducing gas discharged from all or part of the fluidized bed is collected by a cyclone dust collector before entering the adjacent fluidized bed. ​ 8. The method for preparing high metallization rate DRI as described in claim 2, characterized in that, The fluidized bed group is a multi-stage circulating fluidized bed group with 3 to 7 stages; the fluidized bed group and the corresponding fluidized bed process are selected from one of the following forms: a) Iron ore powder is added from the last stage fluidized bed, passes through each stage of fluidized bed in sequence, and is discharged from the first stage fluidized bed; b) The fluidized bed is divided into a coarse particle bed and a fine particle bed, and the fluidized bed is connected to a particle classification device: Before entering the fluidized bed unit, the iron ore powder first enters the particle classification device, where it is separated into fine particles and coarse particles, and then enters the coarse particle bed unit and the fine particle bed unit respectively for reduction.

9. The method for preparing high metallization rate DRI as described in claim 8, characterized in that, The fluidized bed assembly also includes the following technical features: c) The multi-stage circulating fluidized bed group is a cooled multi-stage circulating fluidized bed group, with the first stage circulating fluidized bed being a cooled reduction bed and the rest being heated reduction beds: The low-temperature reducing gas enters from the bottom of the first-stage circulating fluidized bed, and after passing through the first-stage circulating fluidized bed, it enters the second-stage circulating fluidized bed, where it merges with the high-temperature reducing gas. d) The multi-stage circulating fluidized bed group is a cooled multi-stage circulating fluidized bed group. The next stage circulating fluidized bed is a cooled reduction bed, and the rest are heated reduction beds. The material outlet of the next stage circulating fluidized bed is connected to the next stage circulating fluidized bed through the magnetic separation device. The low-temperature reducing gas enters from the bottom of the next stage circulating fluidized bed, passes through the next stage circulating fluidized bed, and enters the last stage circulating fluidized bed. The high-temperature reducing gas of the next stage circulating fluidized bed directly enters the last stage circulating fluidized bed.

10. The method for preparing high metallization rate DRI as described in claim 8, characterized in that, When the fluidized bed is in the form of a) or b), the cooling of the reduced DRI powder is accomplished by a cooling device outside the fluidized bed.

11. The method for preparing high metallization rate DRI as described in claim 9, characterized in that, When the fluidized bed group is a combination of b) and c), the first-stage circulating fluidized bed is a coarse-particle bed group. Coarse and fine particles are discharged from their respective bed groups and merged into the first-stage circulating fluidized bed; Low-temperature reducing gas passes through all bed groups in sequence; The high-temperature reducing gas passes through the fine particle bed in sequence and the coarse particle bed in sequence, or the high-temperature reducing gas is introduced from the second-stage circulating fluidized bed and then passes through each stage of the fluidized bed in sequence.

12. The method for preparing high metallization rate DRI as described in claim 2, characterized in that, The fluidized bed group is a multi-layer bubbling fluidized bed, or a series or parallel connection of several multi-layer bubbling fluidized beds. Preferably, the multi-layer bubbling fluidized bed is an air-classified multi-layer cone bed. In a further preferred embodiment, in the air-classified multi-layer cone bed, the bottom layer or the bottom layer plus the next bottom layer is a cooling reduction bed, and the other layers are heating reduction beds. Finally, the reduced DRI powder leaves the air-classified multi-layer cone bed from the bottom cooling reduction bed.

13. The method for preparing high metallization rate DRI as described in any one of claims 2 to 12, characterized in that, The fine crushing process can be set up in the method in one of the following ways: a) The fine crushing process is completed before the fluidized bed process reduction. The iron ore powder is first finely crushed, then enters the fluidized bed process for reduction, and then cooled and dry magnetically separated. b) First, the iron ore powder is coarsely crushed, then reduced in a fluidized bed process, and then finely crushed after exiting the fluidized bed group, followed by cooling and dry magnetic separation. c) The iron ore powder is reduced in a fluidized bed process, then cooled, crushed, and then dry magnetically separated; d) After the iron ore powder is reduced in the fluidized bed process, it is finely crushed and dry magnetically separated in the fluidized bed group, and then enters the fluidized bed process again to complete the reduction.

14. The method for preparing high metallization rate DRI as described in claim 13, characterized in that, Method c) specifically refers to: When the fine crushing process is arranged after the material particles have been reduced, the material particles are cooled and transported to the fine crushing device by carrier gas for fine crushing. The particles with high iron content and particles with low iron content are separated by magnetic separation. The particles with high iron content enter the separation bin and the particles with low iron content enter the separation bin. The particles with high iron content are the high metallization rate (DRI). Preferably, the carrier gas is a reducing gas in the fluidized bed, or the carrier gas is an oxygen-free gas; more preferably, the oxygen-free gas is selected from at least one of nitrogen or carbon dioxide, and when the carrier gas is an oxygen-free gas, an airlock valve is provided at the material particle discharge point.

15. An integrated device for processing tailings, characterized in that, This includes a distribution system, a smelting system, a slag treatment system, and a molten iron system; The material delivery system is used to transport tailings into the smelting system; The smelting system includes a tailings furnace, which consists of a shell, a furnace base, refractory materials, and cooling walls. The furnace body, from bottom to top, comprises the molten iron zone, the slag zone, and the furnace chamber. The furnace zone is equipped with a feed inlet, and the top of the furnace zone is equipped with a gas outlet, an electrode inlet, and a gas sealing device. Outside the furnace, there are electrodes, electrode clamping devices, and power distribution devices. The electrodes enter the tailings furnace from the electrode inlet. The slag zone is equipped with a U-shaped injection port and a U-shaped slag outlet, and the U-shaped slag outlet is equipped with a tiltable slag pot; The molten iron section has an iron tapping point; The slag treatment system includes a water spraying device and a water slag storage and transportation device and a water treatment device connected to the water spraying device. The water spraying device is located below the molten slag ladle. The molten iron system includes a molten iron ladle and a conveying device and a casting machine connected to the molten iron ladle for steelmaking, with the molten iron ladle located below the taphole.

16. The integrated device as claimed in claim 15, characterized in that, The material delivery system can take one of the following three forms: Method 1: The feeding system includes a tailings bin, a solvent bin, and a granular carbon bin. The outlets of the tailings bin, solvent bin, and granular carbon bin are all connected to an airlock feeder, which is then connected to the tailings preheating bin, solvent preheating bin, and granular carbon preheating bin, respectively. The outlets of the tailings preheating bin, solvent preheating bin, and granular carbon preheating bin are all connected to a dispensing feeder, which is then connected to a mixing feeder. The mixing feeder is connected to the inlet of the tailings furnace. Preferably, the tailings preheating bin, solvent preheating bin, and granular carbon preheating bin are all provided with a preheating bin air inlet connected to the tailings bin air outlet, and the tailings preheating bin, solvent preheating bin, and granular carbon preheating bin are all provided with a preheating bin air outlet. Method 2: The feeding system includes a tailings bin, a solvent bin, and a granular carbon bin. The outlets of the tailings bin, solvent bin, and granular carbon bin are all connected to a mixing feeder. A counterweight feeder is also connected between the outlets of the tailings bin, solvent bin, and granular carbon bin and the mixing feeder. The outlet of the mixing feeder is connected to the inlet of the combined preheating bin. The outlet of the combined preheating bin is connected to the inlet of the tailings furnace through a screw feeder. Preferably, the combined preheating bin has a preheating bin air inlet connected to the outlet of the tailings bin, and the combined preheating bin has a preheating bin air outlet. Method 3: The feeding system is a tailings injection device. The tailings are injected into the slag pool inside the tailings furnace through the spray gun of the tailings injection device. The spray gun is equipped with a water-cooled sleeve.

17. The integrated device as claimed in claim 16, characterized in that, The connection method between the mixing feeder in Method 1 or the screw feeder in Method 2 and the feed inlet of the tailings furnace is as follows: The feed inlet is located on the side wall of the tailings furnace in the furnace zone, and the outlet of the mixing feeder or screw feeder is connected to the feed inlet; Alternatively, the tailings furnace is equipped with a feed pipe, one end of which is connected to the outlet of the mixing feeder or screw feeder, and the other end of which is a feed inlet, which is connected to an annular feeding pipe that is inclined around the motor. Alternatively, the tailings furnace may be equipped with a feed pipe, one end of which is connected to the outlet of the mixing feeder or screw feeder, and the other end of which is a feed inlet. The feed inlets are arranged corresponding to each electrode, so that the tailings can be thrown to the vicinity of the arc zone released by the electrode.

18. The integrated device according to any one of claims 15 to 17, characterized in that, It also includes one or more of the following technical features: The U-shaped slag outlet is a U-shaped liquid-sealed slag outlet; The tailings furnace is also equipped with an oxygen-containing gas inlet; The tailings preheating chamber, solvent preheating chamber, and granular carbon preheating chamber are arranged in a hyperbolic conical shape. The slag bag is insulated and / or equipped with an electric heating device; The furnace zone is equipped with a liquid steel slag inlet at the top.

19. A method for treating tailings using the integrated tailings treatment device according to any one of claims 15-18, characterized in that, Includes the following steps: Tailings, solvent and particulate carbon are mixed using the feeding system to form a mixture and fed into the tailings furnace, where they are heated and melted by an electric arc released from the electrodes. The tailings are added in powder form. The molten slag from the electric furnace and / or converter is fed into the tailings furnace through a U-shaped inlet to melt and mix with the tailings slag. After the slag in the tailings furnace is discharged through the U-shaped slag outlet, it is mixed in a slag ladle and then discharged from the ladle for water quenching. The by-product molten iron produced during the slag melting process in the tailings furnace flows from the tapping port into the molten iron ladle and is cast into block iron or foundry iron or directly sent into the steelmaking furnace. The furnace gas flows out from the outlet, and its sensible heat and / or chemical heat are used for drying and preheating of the tailings, solvents, and carbon particles entering the tailings furnace.

20. The method for processing iron ore tailings as described in claim 19, characterized in that, The method of feeding the mixture into the tailings furnace is selected from any of the following: a) When the mixture is fed into the tailings furnace, it is buried in the solid material pile inside the furnace. The solid material is allowed to enter by applying pressure to the solid material at the feed port. b) The mixture is thrown into the area where the electrodes release the electric arc through the feed pipe extending into the tailings furnace; c) The mixture enters the tailings furnace through the feed pipe and is arranged in the area where the electrode releases the electric arc through the inclined annular distribution pipe that surrounds the electrode. d) When the mixture is fed into the tailings furnace, it is sprayed into the slag pool through the spray gun of the tailings injection device.

21. A direct steelmaking apparatus, characterized in that, Includes the high metallization rate DRI preparation equipment as described in claim 1, the tailings treatment integrated device as described in any one of claims 15-18, the briquetting device, and the converter: The briquetting device is used to briquette the high metallization rate DRI powder magnetically separated by the magnetic separation device of the high metallization rate DRI preparation equipment, and then transfer it to the converter for direct steelmaking. The tailings treatment integrated device is used to process low-iron-content material particles magnetically separated by the magnetic separation device of the high metallization rate DRI preparation equipment.

22. A direct steelmaking method, characterized in that, The process includes the following steps: High metallization rate DRI powder preparation process: High metallization rate DRI powder is prepared using the preparation method of high metallization rate DRI according to any one of claims 2 to 14; Steelmaking process: The high metallization rate DRI powder is briquetized by a briquetting device and then fed into a converter for steelmaking.

23. The direct steelmaking method as described in claim 22, characterized in that, In the high metallization rate DRI powder preparation process, the low iron content material particles selected by the magnetic separation device are processed by the tailings treatment method described in claims 19-20.

24. The direct steelmaking method as described in claim 23, characterized in that, In the steelmaking process, the liquid slag produced in the converter is injected into the tailings furnace through the U-shaped inlet for the tailings treatment process. In the tailings treatment process, the molten iron produced in the tailings furnace is injected into the converter for use in the steelmaking process. In the high metallization rate DRI powder preparation process, the reducing gas enters the tailings treatment process along with the low iron content material particles. After being heated in the tailings furnace, it is returned to the fluidized bed process.

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