Steel slag modification and valuable element recovery device and method

Abstract

The application discloses a steel slag modification and valuable element recovery device and method, and belongs to the technical field of solid waste treatment in metallurgical industry. The steel slag modification and valuable element recovery device comprises a rotary tilting system and a spray gun system, wherein the rotary tilting system comprises a modification reduction furnace and a tilting frame, the modification reduction furnace is arranged in the tilting frame, the modification reduction furnace can rotate around a furnace body center shaft in the tilting frame and tilt around a tilting shaft of the tilting frame; the spray gun system comprises a powder spraying and heat supplement gun and a rotary lifting mechanism, the powder spraying and heat supplement gun is arranged on the upside of a charging furnace mouth at the top of the modification reduction furnace, one end of the rotary lifting mechanism is connected with the powder spraying and heat supplement gun, and the other end is connected with one side of the tilting shaft. The device and method provided by the application effectively improve the stirring dynamics conditions of the modification reduction process, the molten slag is heated, modified and treated by carbon thermal reduction by using the powder spraying and heat supplement gun, and the valuable elements such as phosphorus, iron and manganese in the steel slag are recovered.

Description

Technical Field

[0001] This invention belongs to the field of solid waste treatment technology in the metallurgical industry, and specifically relates to a device and method for steel slag modification and valuable element recovery. Background Technology

[0002] my country has a large steel production, with crude steel output reaching 1.032 billion tons in 2021, generating over 100 million tons of steel slag. Since steel slag contains valuable elements such as phosphorus and iron, physical methods cannot effectively separate and recover them. Many experts and scholars have proposed using carbothermic reduction to reduce iron oxides in the slag into molten iron, which can effectively separate and recover the slag. During the reduction process, the reduced phosphorus can also enter the molten iron, thus achieving effective recovery and utilization of phosphorus and iron resources in the slag. On the other hand, the high basicity of the slag limits its recycling. Therefore, many researchers have proposed adding substances such as silica sand, mainly composed of SiO2, after the steel slag is discharged. This can effectively reduce the basicity of the slag, thereby increasing the utilization pathways of the steel slag. In particular, low-basicity steel slag can be widely used in basic materials. Based on the above two backgrounds, current research often involves adding carbon powder as a reducing agent and SiO2 as a modifier during converter slag removal to simultaneously reduce and recover valuable elements such as phosphorus and iron from steel slag and increase the utilization pathways of steel slag. However, due to poor kinetic conditions between steel slag, carbon powder, and modifier, as well as poor heating conditions, valuable elements such as phosphorus and iron in the slag cannot be reduced efficiently. Furthermore, the modified steel slag is uneven, and the free calcium oxide content still does not meet the requirements for building materials. Therefore, there is a need to invent a device that can simultaneously modify and reduce steel slag, improving kinetic and heating conditions to achieve efficient reduction and modification of steel slag. Summary of the Invention

[0003] Based on the above analysis, the present invention aims to provide a device and method for steel slag modification and valuable element recovery, in order to solve at least one of the problems of poor kinetic conditions and poor temperature compensation conditions in existing modification and reduction processes.

[0004] The objective of this invention is mainly achieved through the following technical solutions:

[0005] On one hand, the present invention provides a steel slag modification and valuable element recovery device, including a rotary tilting system and a spray gun system. The rotary tilting system includes a modification and reduction furnace and a tilting frame. The modification and reduction furnace is disposed within the tilting frame and can rotate within the tilting frame about the central axis of the furnace body and tilt about the tilting axis of the tilting frame. The spray gun system includes a powder injection and heating gun and a rotary lifting mechanism. The powder injection and heating gun is disposed above the feeding port at the top of the modification and reduction furnace. One end of the rotary lifting mechanism is connected to the powder injection and heating gun, and the other end is connected to one side of the tilting axis.

[0006] Preferably, the powder spraying and heating gun comprises:

[0007] The first pipe is for adding powder.

[0008] The second pipe, surrounding the first pipe, is a gas pipeline.

[0009] The third pipe, surrounding the second pipe, is a gas-supporting pipe.

[0010] Preferably, the modified reduction furnace is connected within the tilting frame via a rotary support provided inside the tilting frame.

[0011] Preferably, the rotary lifting mechanism includes:

[0012] The lifting arm is connected at one end to the powder spraying and heating gun and at the other end to the guide mechanism;

[0013] The column is connected to the guide mechanism at one end and has a pivot hole at the other end, which is rotatably connected to the tilting shaft of the tilting frame.

[0014] Preferably, the rotary lifting mechanism further includes a chain, which is mounted on a column. Both ends of the chain are connected to a guide mechanism. Additionally, sprockets are mounted on the upper and lower sides of the column, and the chain is sleeved on the sprockets.

[0015] Preferably, a pressure wheel and a drive wheel are provided on the side of the column, and the chain is sleeved on the pressure wheel and the drive wheel.

[0016] Preferably, a tapping mechanism is provided at the bottom of the modified reduction furnace, the tapping mechanism comprising:

[0017] The rotating part is installed at the bottom of the modification and reduction furnace, and has a tapping hole in the middle.

[0018] The first sliding plate is set on the underside of the seat brick and is slidably connected to the bottom of the modified reduction furnace. A first through hole is provided on the left side of the first sliding plate.

[0019] The second slide plate is located below the first slide plate and is slidably connected to the first slide plate. The second slide plate has a second through hole on its left side and a third through hole in its middle. A sand filling device is located below the second through hole.

[0020] Preferably, the sand-filling device includes:

[0021] A longitudinal extrusion device is disposed on the lower side of the second through hole and communicates with the second through hole;

[0022] A transverse extrusion device is connected at one end to the longitudinal extrusion device, and a sand storage bin is provided on the upper side of the other end, which is connected to the transverse extrusion device.

[0023] Preferably, when the first through hole is connected to the third through hole and the steel outlet hole of the seat brick, it is the steel outlet position; when the first through hole is connected to the second through hole, it is the sand filling position.

[0024] On the other hand, the present invention provides a method for steel slag modification and valuable element recovery, using the above-mentioned steel slag modification and valuable element recovery device, comprising the following steps:

[0025] Step 1: After the primary smelting furnace has finished tapping steel, during the high-temperature steel slag dumping process, a modifier is added in advance at the bottom of the modification and reduction furnace or along with the liquid slag flow, and the residual heat of the steel slag and the slag discharge power are used to melt and modify the slag.

[0026] Step 2: After pouring the modified hot slag from Step 1 into the modification and reduction furnace online, gas is injected at the furnace opening to reheat the slag and simultaneously agitate the slag in the molten pool.

[0027] Step 3: The molten slag is heated in the modification and reduction furnace, and a reducing agent is injected into the modified molten slag at the furnace opening;

[0028] Step 4: After reduction, the molten slag pool is calmed to achieve stratification of molten slag and molten iron. Then, the molten iron is discharged from the bottom of the modified reduction furnace, and the slag is discharged from the furnace opening by flipping the furnace.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] A) The steel slag modification and valuable element recovery device and method provided by the present invention can effectively improve the stirring dynamics conditions of the modification and reduction process by rotating and tilting the modification and reduction furnace. The molten slag is heated, modified and carbotherm reduced by the powder injection heating gun, so as to realize continuous heating and effective modification and reduction of steel slag, and realize the recovery of valuable elements such as phosphorus, iron and manganese in steel slag.

[0031] B) The steel slag modification and valuable element recovery device provided by the present invention has a powder injection heating gun that is coaxial with the tilting frame and operates independently. It can tilt synchronously with the furnace body. During the tilting process, powder is injected or burned to achieve synchronous heating or reduction modification during the stirring process. The high-temperature gas generated by combustion impacts the slag layer at a certain speed. At the same time, the powder is entrained into the high-temperature gas by the ejector principle so that the powder can enter the slag layer for reaction. The high-speed gas plays a role in stirring the molten pool while providing heating.

[0032] C) The steel slag modification and valuable element recovery device provided by the present invention adopts steel tapping at the bottom of the furnace and slag tapping at the top of the furnace. The bottom steel tapping system is equipped with a sand filling device, which can realize both bottom steel tapping and bottom sand filling. It can be used repeatedly while maintaining a molten pool in the furnace.

[0033] D) The steel slag modification and valuable element recovery device provided by this invention can achieve efficient recovery of valuable elements from steel slag. This plays a crucial role in reducing land occupation and environmental pollution caused by the large-scale dumping of dephosphorized steel slag and increasing the economic benefits of steel enterprises. Therefore, this invention has important reference and guiding significance for the efficient recycling of dephosphorized steel slag in steel enterprises.

[0034] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0035] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0036] Figure 1 An exploded perspective view of the device provided by the present invention.

[0037] Figure 2 A front view of the device provided by the present invention.

[0038] Figure 3 Right view of the device provided by the present invention.

[0039] Figure 4 This is a schematic diagram of the spray gun provided by the present invention.

[0040] Figure 5 This is a cross-sectional view of the modified reduction furnace provided by the present invention.

[0041] Figure 6 for Figure 5 Enlarged view of part A.

[0042] Figure 7SEM image of dephosphorized converter slag in Example 1 provided by the present invention.

[0043] Figure 8 Photograph of the metallic iron block obtained after the dephosphorization converter slag in Example 1 of the present invention has been treated by this method.

[0044] Figure 9 Photograph of the slag sample obtained after the dephosphorization converter slag in Example 1 of the present invention has been processed by this method.

[0045] Figure 10 SEM image of electric furnace steel slag in Example 2 provided by the present invention.

[0046] Figure 11 Photograph of the metal iron block obtained after processing electric furnace steel slag by this method in Example 2 of the present invention.

[0047] Figure 12 Photograph of the slag sample obtained after processing electric furnace steel slag using this method in Example 2 of the present invention.

[0048] Figure label:

[0049] 1-Base, 2-Tilting drive, 3-Angular displacement sensor, 4-Tilting frame, 41-Tilting shaft, 5-Rotation support, 6-Reduction furnace, 7-Rotation drive, 8-Spray gun system, 9-Steel tapping system, 10-Powder spraying and reheating gun, 11-Pressure block, 12-Lifting crossarm, 13-Guide mechanism, 14-Column, 141-Sprocket, 142-Pressure wheel, 143-Drive wheel, 144-Shaft hole, 15-Chain, 16-Lifting motor, 17-Encoder, 18-Rotation drive, 19-Angular displacement sensor, 20-First pipe, 21-Second pipe, 22-Third pipe, 211-Gas inlet. 221-Gas supply hole, 23-First transverse movement mechanism, 24-Sand storage bin, 25-Transverse extrusion device, 26-Vertical extrusion device, 27-Brick seat, 271-Steel tap hole, 28-First slide plate, 281-First through hole, 29-Second slide plate, 291-Second through hole, 292-Third through hole, 30-Second transverse movement mechanism, 61-Furnace body base. Detailed Implementation

[0050] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0051] Reference Figures 1-6 This invention provides a device for steel slag modification and valuable element recovery, comprising a rotary tilting system and a spray gun system, wherein...

[0052] The rotation and tilting system includes a modified reduction furnace 6 and a tilting frame 4. The modified reduction furnace 6 is set inside the tilting frame 4. The modified reduction furnace 6 can rotate within the tilting frame 4 about the central axis of the furnace body (Y-axis in the figure) and tilt about the tilting axis 41 of the tilting frame 4 (X-axis in the figure). The rotation and the tilting operate independently.

[0053] The spray gun system 8 includes a powder spraying and heating gun 10 and a rotary lifting mechanism. The powder spraying and heating gun 10 is located on the upper side of the feeding port at the top of the modified reduction furnace 6. One end of the rotary lifting mechanism is connected to the powder spraying and heating gun 10, and the other end is connected to one side of the tilting shaft 41.

[0054] Specifically, the rotary lifting mechanism can drive the powder injection heating gun 10 to extend into or out of the charging port of the reforming and reduction furnace 6, and drive the powder injection heating gun 10 to swing and rotate in the tilting direction of the reforming and reduction furnace 6, thereby realizing the heating or reforming and reduction of the steel slag in the furnace.

[0055] The steel slag modification and valuable element recovery device provided by this invention can effectively improve the stirring dynamics of the modification and reduction process by rotating and tilting the modification and reduction furnace. The powder injection heating gun can tilt with the furnace body and extend into the modification and reduction furnace under the drive of the rotating lifting mechanism. The powder injection heating gun is used to heat, modify and carbotherm reduce the molten slag, realize the continuous heating and effective modification and reduction of steel slag, and thus realize the recovery of valuable elements such as iron, phosphorus and manganese in steel slag.

[0056] Specifically, the modified reduction furnace 6 can be connected to the tilting frame 4 through the rotating support 5 set inside the tilting frame 4. The modified reduction furnace 6 can rotate 360° around the Y-axis under the support and drive of the rotating support 5.

[0057] Preferably, the rotating support 5 can be a roller, which is set inside the tilting frame 4. A protruding rib can be set in the middle of the modified reduction furnace 6, and the rotating support 5 can be rolled and engaged with the protruding rib.

[0058] Specifically, the rotating support 5 can be connected to the rotating drive 7 to drive the rotation of the rotating support 5. The rotating support 5 connected to the rotating drive 7 can be a drive roller, and the rotating support 5 not connected to the rotating drive 7 can be a guide roller. Preferably, in this invention, the tilting frame 4 is equipped with 3 guide rollers and 1 drive roller as an example for illustration. However, the invention is not limited to this. When the furnace body is large, more than 2 rotating drives 7 and more rotating supports 5 can be used to drive the furnace body to rotate.

[0059] Specifically, one end of the tilting shaft 41 can be connected to the tilting drive 2, which is called the drive shaft. The tilting drive 2 is connected to an angular displacement sensor 3. The reforming and reduction furnace 6 can be tilted along the X-axis by the tilting drive 2 along with the tilting frame 4. The tilting angle during the reforming and reduction process is generally ±30°. When the reforming is completed and all the slag in the furnace needs to be poured out, the tilting frame 4 can rotate more than 180° to pour out the slag.

[0060] It should be noted that the control system can read the signal from the angular displacement sensor 3 to obtain the current tilting position of the furnace body. The angular displacement sensor 3, combined with the control system, realizes closed-loop control of the furnace body's attitude. For example, different work positions such as slag receiving, stirring, and slag dumping can be preset. According to the system instructions, the system is driven to tilt and rotate in the specified direction. When the furnace body reaches the specified position, the tilting stops and is locked. Specifically, for example, when the modified reduction furnace 6 needs to receive slag, the modified reduction furnace 6 tilts vertically or towards the slag receiving direction at a certain angle. The angular displacement sensor 3 can compare with the control signal, and then the control system tilts the modified reduction furnace 6 to the slag receiving angle. When it is necessary to fully stir the molten slag during the modification and reduction process, the angular displacement sensor 3 can compare with the control signal and drive the furnace body to tilt repeatedly within a certain range according to the control signal, promoting the homogenization of the molten pool and providing good kinetic conditions for the modification reaction.

[0061] It should be noted that the rotation and tilting of the modified reduction furnace are driven by the rotation drive 7 and the tilting drive 2, respectively. During operation, rotation or tilting can be performed independently, or both can be performed simultaneously, depending on actual needs.

[0062] Specifically, the device may also include a base 1, which is set on the ground. The tilting shaft 41 of the tilting frame 4 is connected to the base 1, making the operation of the rotation tilting system more stable.

[0063] Specifically, the powder spraying and heating gun 10 can be composed of three layers of tubing. The first pipe 20 is the middle pipe, which is the powder addition pipe. The powder can be a modifier or a reducing agent. The second pipe 21 surrounds the middle pipe 20 and is the gas pipe. The third pipe 22 surrounds the second pipe and is the combustion-supporting pipe. The second pipe 21 and the third pipe 22 can be respectively provided with a gas inlet hole 211 and a combustion-supporting hole 221 on the side.

[0064] It should be noted that the powder-injected heating lance 10 adds powder (reducing agent and modifier) ​​to the steel slag during the modification and reduction process. The main function of the fuel gas is to heat and replenish the temperature of the molten slag. The fuel gas can be natural gas, propane, or coal gas, while the auxiliary fuel gas can be air, pure oxygen, or a mixture of both in oxygen-enriched air. The lance adopts a high-speed design with a jet exit velocity >80m / s. The high-temperature, high-speed jet carries the modifying powder and impacts the slag surface, forming a high-temperature melting zone. The high-speed gas not only provides heating but also stirs the molten pool, which is beneficial to the modification reaction. The lance's combustion system is configured for complete combustion, with a fuel gas to auxiliary fuel gas ratio of 1:1 to 1:1.05 (this ratio is for complete combustion and only calculates the portion of the gas that participates in the reaction, not the actual amount of gas). The combustion flame is a neutral or weakly oxidizing flame to reduce and avoid burn-off of the injected powder.

[0065] It should be noted that the size of the medium pipeline in the powder spraying and heating gun 10 is determined according to the powder dosage required for the reaction and the amount of combustion gas required for heating. Specifically, the diameter of each medium pipeline in the powder spraying and heating gun 10 ranges from DN10 to DN150, with a preferred range of DN10 to DN65.

[0066] In one specific embodiment, the diameter of the first pipe 20 (powder addition pipe) is DN15-DN40. When the combustion-supporting gas is pure oxygen, the diameters of the second pipe 21 (gas pipe) and the third pipe 22 (combustion-supporting pipe) are DN25-DN50. When the combustion-supporting gas is air, the diameters of the second pipe 21 (gas pipe) and the third pipe 22 (combustion-supporting pipe) are DN25~DN150.

[0067] It should be noted that the powder spraying and heating gun 10 can spray gas or powder separately as needed, or spray gas or powder simultaneously as needed.

[0068] Specifically, the rotating lifting mechanism includes a lifting arm 12, a guide mechanism 13, and a column 14, wherein,

[0069] The lifting horizontal arm 12 is connected at one end to the powder spraying and heating gun 10 and at the other end to the guide mechanism 13;

[0070] The column 14 has one end connected to the guide mechanism 13, allowing the lifting arm 12 to slide along the column 14. The other end is provided with a pivot hole 144, which is rotatably connected to the tilting shaft 41 of the tilting frame 4. Preferably, the pivot hole 144 can be mounted on the passive shaft side (the side without tilting drive) of the tilting shaft 41 via a bearing (not shown), thereby achieving a rotatable connection between the pivot hole 144 and the tilting shaft 41.

[0071] It should be noted that during the reforming and reduction process, the furnace body may rotate, tilt, or rotate and tilt simultaneously. When it is necessary to spray reducing agent, reforming agent, or fuel gas, the powder injection and heating gun will tilt and move downwards into the furnace body along with the furnace body. When the spray gun is not needed, it will move upwards and remain stationary, without tilting with the furnace body.

[0072] The steel slag modification and valuable element recovery device provided by this invention has a powder injection heating gun that is coaxial with the tilting frame and operates independently. It can tilt synchronously with the furnace body. During the tilting process, powder is injected or burned to achieve synchronous heating or reduction modification during the stirring process. The high-temperature gas generated by combustion impacts the slag layer at a certain speed. At the same time, the powder is entrained into the high-temperature gas by the ejector principle so that the powder can enter the slag layer for reaction. The high-speed gas plays a role in stirring the molten pool while providing heating.

[0073] Preferably, in order to further control the sliding of the guide mechanism 13 on the column, the rotary lifting mechanism may also include a chain 15, which is disposed on the column 14. The two ends of the chain are respectively connected to the guide mechanism 13. Meanwhile, sprockets 141 are disposed on the upper and lower sides of the column 14, and the chain 15 is sleeved on the sprockets.

[0074] Preferably, the guide mechanism 13 can be a sleeve fitted onto the column 14. Connecting plates are provided at both the top and bottom of the connection end between the lifting arm 12 and the guide mechanism 13. Both ends of the chain 15 are connected to the top and bottom connecting plates of the guide mechanism 13, respectively. Additionally, a pressure wheel 142 and a drive wheel 143 can be provided on the side of the column 14. The chain 15 is fitted onto the pressure wheel 142 and the drive wheel 143. The drive wheel 143 drives the chain 15 to move and lift, while the pressure wheel 142 further stabilizes the movement of the chain 15.

[0075] Preferably, the rotary lifting mechanism may further include a lifting motor 16 connected to the drive wheel 143. An encoder 17 is connected to the rotating shaft on one side of the lifting motor 16 to convert the rotation signal into a series of pulse signals and send them to the control system. The control system determines the rotation angle by detecting the pulses, calculates the current gun position, and compares it with the gun position set by the control system to determine whether the gun body has reached the preset position.

[0076] Preferably, the lifting column 14 is located on the passive shaft side of the tilting shaft 41 and is equipped with an independent rotary drive 18. The drive can be achieved through a hydraulic cylinder. One end of the rotary drive 18 is connected to the lower side of the column 14, and the other end is connected to the base 1. The rotary drive 18 can drive the column 14 to rotate synchronously with the tilting frame 4 or rotate independently, with a maximum rotation angle of ±45°, thereby meeting different functional requirements. An angular displacement sensor 19 is installed at the pivot hole of the column 14 to display the current rotation angle of the column 14 for easy control.

[0077] Preferably, one end of the lifting arm 12 is connected to the spray gun 10 via a pressure block 11.

[0078] Specifically, the bottom of the modified reduction furnace 6 is equipped with a steel tapping mechanism 9, including:

[0079] The rotating part 27 is installed through the bottom of the reforming and reduction furnace 6, and has a tapping hole 271 in the middle for tapping steel.

[0080] The first sliding plate 28 is located on the underside of the seat brick 27 and is slidably connected to the bottom of the seat brick 27 and the modified reduction furnace 6. The first sliding plate 28 has a first through hole 281 on its left side.

[0081] The second slide plate 29 is located below the first slide plate 28 and is slidably connected to the first slide plate 28. A second through hole 291 is provided on the left side and a third through hole 292 is provided in the middle. A sand filling device is provided below the second through hole 291.

[0082] It should be noted that when the first through hole 281 is connected to the third through hole 292 and the steel outlet hole of the seat brick 27, it is the steel outlet position, and iron elements flow out; when the first through hole 281 is connected to the second through hole 291, it is the sand filling position, which is used to fill the steel outlet hole with sand.

[0083] Specifically, the sand-filling device includes:

[0084] The longitudinal extrusion device 26 is disposed on the lower side of the second through hole 291 and communicates with the second through hole 291;

[0085] The transverse extrusion device 25 is connected to the longitudinal extrusion device 26 at one end, and a sand storage bin 24 is provided on the upper side of the other end. The sand storage bin 24 is connected to the transverse extrusion device 25.

[0086] Preferably, the transverse extrusion device 25 and the longitudinal extrusion device 26 can be piston extrusion or spiral continuous extrusion.

[0087] Preferably, the right side of the first slide plate 28 is connected to the second lateral movement mechanism 30 to drive the sliding of the first slide plate 28. This mechanism can be a hydraulic cylinder, with one end fixedly connected to the bottom of the furnace body and the other end connected to the first slide plate 28. The connection end of the transverse extrusion device 25 and the sand storage bin 24 is connected to the first lateral movement mechanism 23 to drive the sliding of the second slide plate 29. This mechanism can be a hydraulic cylinder and can be fixedly connected to the bottom of the furnace body.

[0088] Preferably, in order to further stabilize the first sliding plate 28 and the second sliding plate 29, a furnace base 61 can be provided at the bottom of the furnace body, with the base brick 27 penetrating through the furnace base, and the first sliding plate 28 slidably connected to the furnace base 61.

[0089] The specific implementation process for steel tapping and sand filling is as follows:

[0090] When the molten metal accumulated in the molten pool reaches a certain level, the first slide plate 28 slides to the right under the action of the second transverse mechanism 30. The first through hole 281 on the first slide plate 28 communicates with the steel tapping hole of the seat brick 27 and the third through hole 292 of the second slide plate 29. At this time, it is the steel tapping position, and the molten metal accumulated at the bottom of the furnace body 6 flows out. When the molten metal reaches a certain level, the first slide plate 28 slides to the left under the action of the second transverse mechanism 30. The first through hole 281 is misaligned with the steel tapping hole and the third through hole 292 of the seat brick 27, and the steel tapping process stops. At this time, the first through hole 281, the second through hole 291, and the longitudinal extrusion device 26 are connected. This is the sand filling position.

[0091] After the first slide plate 28 moves to the left sand filling position, the transverse extrusion device 25 and the longitudinal extrusion device 26 are activated in sequence to fill the guiding sand into the first through hole 281 and the second through hole 291. After the above process is completed, the first slide plate 28 and the second slide plate 29 move to the right under the drive of the second transverse mechanism 30 and the first transverse mechanism 23, respectively. The steel outlet hole of the seat brick 27, the first through hole 281, the second through hole 291, and the longitudinal extrusion device 26 are connected. The guiding sand is filled into the steel outlet hole of the seat brick 27 under the extrusion of the longitudinal extrusion device 26. After filling is completed, the sand storage bin 24, the transverse extrusion device 25, the longitudinal extrusion device 26, and the second slide plate 29 slide to the left under the drive of the first transverse mechanism 23 and return to the sand filling position. At this time, the sand filling is completed.

[0092] It should be noted that this device uses bottom steel tapping and top slag tapping, and the bottom steel tapping system is equipped with a sand filling device, which can achieve both bottom steel tapping and bottom sand filling, and can be reused repeatedly while maintaining a molten pool inside the furnace.

[0093] The apparatus provided by this invention allows the modification and reduction furnace to rotate 360 ​​degrees along the X-axis, which facilitates the loading of slag dumped from the converter. Simultaneously, the furnace can rotate along its centerline (Y-axis) to promote stirring of the molten pool. This ensures thorough mixing of the slag, reducing agent, and modifying agent, improving the reduction rate and uniformity of the phosphorus and iron resources in the slag. The powder injection heating lance employs a multi-layer sleeve design, with the central pipe capable of simultaneously injecting both reducing agent and modifying agent. This allows the combustion of gas to compensate for the heat required for the reduction and modification reactions, while the high-speed airflow impacting the molten pool promotes uniform distribution of the reducing agent and modifying agent in the slag, providing the necessary kinetic conditions for the reduction and modification reactions. Externally... The circumferential seam allows fuel and combustion-supporting gas to pass through, enabling the spray gun to have a combustion and heat-replenishing function. This increases the temperature of the steel slag, providing the heat required during the steel slag modification process. Simultaneously, it melts the steel slag, improving its fluidity and ensuring the reduction of valuable elements such as phosphorus, iron, and manganese in the steel slag, as well as the combination with the modifier and calcium oxide in the slag. A taphole is provided at the bottom of the modifier furnace, allowing the molten iron formed after the reduction and precipitation of iron elements in the slag to be discharged through the bottom of the modifier furnace, thus achieving slag-iron separation. To adapt to the erosion of the furnace lining caused by changes in alkalinity during the steel slag modification process, a certain amount of alkaline furnace charge is sprayed onto the modifier furnace before each use to reduce the erosion of the main neutral furnace lining after the steel slag is poured in, ensuring the service life of the main refractory material of the modifier furnace.

[0094] The following describes the working process of the steel slag modification and valuable element recovery device provided by the present invention.

[0095] In general, the apparatus provided by this invention involves pouring steel slag into a reforming and reducing furnace after slag discharge. Before loading molten, unreformed steel slag, a certain amount of alkaline refractory material is sprayed into the interior of the reforming furnace using a spray gun. After the steel slag to be reformed is loaded into the reforming furnace, a reforming agent is sprayed in using a spray gun to achieve the purpose of steel slag reforming. After the reforming agent is added, a reducing agent is added to reduce iron oxides and phosphorus oxides in the steel slag, thereby achieving the purpose of recovering valuable elements from the steel slag. During the addition of the reforming agent and reducing agent, the combustion of gas on the spray gun heats the steel slag to ensure that the steel slag reaches a molten state. After the reforming and reducing is completed, the furnace is allowed to stand to separate the slag and iron. The molten metal flows from the bottom of the reforming furnace, and the remaining steel slag after reforming and reducing is treated accordingly according to its final use.

[0096] Specifically, the reforming and reduction process can be divided into the following stages: slag receiving, reforming and reduction, iron discharge, and slag removal.

[0097] Slag Receiving: When receiving slag, the reforming and reduction furnace should be upright or tilted at a certain angle towards the slag receiving direction. The powder injection and heat replenishment lance should be opened to make room above the furnace opening. The slag pot containing hot slag should be adjusted above the furnace opening by the overhead crane and tilted to pour the hot slag into the reforming and reduction furnace. After the slag is poured out, the furnace body should be straightened, and the powder injection and heat replenishment lance should be rotated to the top of the furnace body. At this time, the furnace body axis should be parallel to the axis of the lance support.

[0098] Modification and Reduction: The lance is ignited to heat the hot slag in the furnace. During heating, the furnace body tilts at a certain angle, generally not exceeding 30°. The rotating device is activated, and the furnace body rotates continuously around its own Y-axis. This process accelerates the melting of the hot slag. After the hot slag has basically melted, the lance begins to inject reducing agent or modifying agent into the furnace. To promote mass transfer and reaction, the furnace body oscillates within a small range (-30° to +30°) along the X-axis under the drive of the tilting system, and the lance performs the same movement as the furnace body.

[0099] Iron discharge: Because the slag contains a large amount of iron oxide, it reacts with the reducing agent at a sufficient temperature to produce iron. Since the reduced iron droplets have a higher density, they sink and accumulate under gravity, eventually forming a molten steel pool of a certain height at the bottom of the furnace. Once the pool reaches a certain height, the taphole at the bottom of the furnace can be opened to discharge and recover the molten steel. Due to the sufficient conditions for the above-mentioned modification and reduction, valuable elements such as P and Mn are also reduced into the molten iron and discharged.

[0100] Slag Removal: After processing, allow the molten metal droplets in the furnace to settle and converge for a certain period. Then, tilt the furnace at a certain angle to pour out the upper layer of molten slag from the furnace opening. Since the bottom of the molten pool contains a large amount of metal, only the upper layer of lower-density slag is poured out during operation, leaving a portion of liquid slag. This reduces metal loss and, on the other hand, a certain height of flowing slag facilitates the melting of newly added slag. When the equipment is shut down or under maintenance, all the molten slag in the furnace needs to be poured out. At this time, simply rotate the furnace to 180°.

[0101] In addition, the present invention also provides a method for steel slag modification and valuable element recovery, comprising the following steps:

[0102] Step 1: After the primary smelting furnace has finished tapping steel, during the high-temperature steel slag dumping process, a modifier is added to the bottom of the modification and reduction furnace in advance or added with the liquid slag flow. The residual heat of the steel slag and the power of slag dumping are used to melt and modify the slag, so as to ensure that the basicity of the steel slag and f-CaO in the slag are reduced while meeting the requirements of raw materials for building and road materials.

[0103] Step 2: After pouring the modified hot slag from Step 1 into the modification and reduction furnace online, gas is injected into the furnace opening to reheat the slag within the range of 1450℃-1650℃, so that the slag is fully melted. At the same time, the slag in the molten pool is stirred to ensure that the molten pool is fully modified and mixed evenly.

[0104] Step 3: After the slag is heated to 1450℃-1650℃ in the reforming and reduction furnace, a reducing agent is sprayed into the reforming and reduction furnace mouth to carry out hot reduction treatment, and the temperature is maintained at the reduction temperature for 10min-1h to ensure that the slag is fully reduced and to improve the recovery rate of valuable elements such as iron, phosphorus and manganese in the slag.

[0105] Step 4: After reduction, the molten slag pool is calmed to achieve stratification of molten slag and molten iron. Then, the molten iron is discharged from the bottom of the modified reduction furnace, and the furnace opening is rotated 180° to discharge slag. The reduced phosphorus-containing molten iron and molten slag are discharged separately to achieve effective separation of steel and slag.

[0106] Step 5: After being processed by the steel slag melting and modification and carbothermic reduction process, the tailings in the tank are introduced into the slag treatment line for subsequent granulation (such as air quenching, hot simmering, etc.). After processing, the steel slag can be directly used to produce mineral wool or meet the requirements for raw materials for building materials such as cement, thus realizing the resource utilization of steel slag.

[0107] Preferably, in order to adapt to the corrosion of the furnace lining caused by the change in alkalinity during the steel slag modification process, a certain amount of alkaline furnace charge is sprayed on the modification and reduction furnace before each use, so as to reduce the corrosion of the main neutral furnace lining after the steel slag is poured in and ensure the service life of the main refractory material of the modification furnace.

[0108] It should be noted that the method for steel slag modification and valuable element recovery provided by this invention is based on the traditional slag discharge process at the end of smelting. It utilizes the large amount of residual heat from the steel slag during the slag discharge process to perform molten modification and carbothermic reduction treatment on the steel slag, so that the steel slag is modified to the target alkalinity. The molten slag is continuously heated by injecting gas and a reducing agent is injected to ensure that the valuable elements in the slag are reduced as much as possible. At the same time, it promotes the dissolution of reduced phosphorus vapor into the molten iron and inhibits the overflow of reduced phosphorus vapor, so as to achieve efficient reduction and maximum recovery of valuable elements in the steel slag. The recovered phosphorus and iron resources can be used to produce ferrophosphate, and the treated steel slag can be directly used to produce mineral wool or used as raw material for cement and other building materials after water quenching.

[0109] Regarding step 1:

[0110] Specifically, in step 1, during the process of dumping high-temperature steel slag, the modified reduction furnace 6 is tilted vertically or at a certain angle towards the slag receiving direction, and the powder injection and heat repair gun 10 is opened to make room above the furnace opening. After dumping the slag, the furnace body is straightened, and the powder injection and heat repair gun is rotated to the top of the furnace body.

[0111] Specifically, the modifier mentioned in step 1 is one or more of siliceous materials and calcareous materials, wherein the siliceous materials include one or more of silica, mud, sand, and SiO2, and the calcareous materials include one or more of lime, limestone, and gravel.

[0112] Specifically, the modifier is added beforehand at the bottom of the modification and reduction furnace, or added with the liquid slag flow between 1 / 5 and 4 / 5 of the slag discharge. The amount of siliceous material added is 0-50% (mass content) of the treated slag, which can be any value between 0-50%, such as 10%, 20%, 30%, 40%, and 50%. The amount of calcareous material added is 0-5% (mass content) of the treated slag, which can be any value between 0-5%, such as 0, 1%, 2%, 3%, 4%, and 5%. The modification target is to reduce the binary basicity of the steel slag to 0.5-1.5, which can be any value between 0.5-1.5, such as 0.8, 0.9, 1, and 1.1.

[0113] It should be noted that when adding the modifier along with the molten slag, if the modifier is added too early, it will directly contact the bottom of the slag pot and easily adhere to it; if the modifier is added too late, the kinetic energy from the slag discharge cannot be utilized, and the modifier will float directly on the slag surface, making it difficult to fully contact and react with the molten slag. Therefore, the modifier should be added with the molten slag during the period between 1 / 5 and 4 / 5 of the slag discharge.

[0114] Specifically, the amount of siliceous material added is 0-50% (by mass) of the treated slag. Adding too much siliceous material increases material costs and also raises the melting point of the slag too high; adding too little siliceous material fails to adequately modify the slag and makes it difficult to fully dissolve free calcium oxide in the slag. Preferably, the amount of siliceous material added is 10-50% (by mass) of the treated slag.

[0115] Specifically, the amount of limestone material added should be 0-5% (by mass) of the treated slag. Adding too much limestone material will result in high material costs and an excessively high melting point of the slag. Adding too little limestone material will not be sufficient to modify the slag and will make it difficult to fully dissolve the excessive free calcium oxide in the slag.

[0116] Regarding step 2:

[0117] Specifically, in step 2, the powder injection heating gun 10 extends into the interior of the modification and reduction furnace 6 to inject gas to replenish the temperature of the steel slag. During the replenishment process, the modification and reduction furnace 6 is tilted, and the powder injection heating gun 10 also swings synchronously with the modification and reduction furnace 6. At the same time, the modification and reduction furnace 6 rotates continuously around its own rotation axis Y. While replenishing the temperature, the rotation and tilting of the modification and reduction furnace 6 can agitate the molten slag in the molten pool, ensuring that the molten pool is fully modified and mixed evenly.

[0118] Specifically, in step 2, the gas injection velocity is above 80m / s, and the injected gas can be used to replenish the temperature of the molten slag. The gas includes one or more of blast furnace gas, coke oven gas, acetylene, natural gas, and methane. The gas is injected into the molten slag to continuously replenish the temperature of the molten slag, and the temperature of the steel slag is controlled within the range of 1450℃-1650℃. The heat value replenished by each ton of steel slag is within the range of 10~50kg of standard coal.

[0119] It should be noted that in step 2, the injection adopts a high-speed design with an injection flow rate of over 80m / s. The high-temperature gas generated by combustion impacts the slag layer at a certain speed. At the same time, the powder (reducing agent or modifier, etc.) is entrained into the high-temperature gas using the ejector principle so that the powder can enter the slag layer for reaction. The high-speed gas not only provides heat but also stirs the molten pool.

[0120] It should be noted that in step 2, if the steel slag temperature is too high, energy consumption will be excessive, resulting in high energy costs; if the steel slag temperature is too low, the molten slag will become sticky or solidify, making it impossible to carry out melting, tempering, and reduction treatments. Therefore, the steel slag temperature should be controlled within the range of 1450℃-1650℃.

[0121] It should be noted that in step 2, the modification and reduction furnace can rotate 360 ​​degrees along the central axis of the furnace body and tilt at the same time, so as to fully mix evenly and improve the stirring kinetics, further promoting the modification and reduction of steel slag.

[0122] Regarding step 3:

[0123] Specifically, in step 3, while the modified reduction furnace 6 is rotating and tilting, the powder injection and heating gun 10 continues to extend into the furnace body to spray reducing agent onto the steel slag, so as to ensure that the slag is fully reduced and improve the recovery rate of valuable elements such as iron, phosphorus, and manganese in the slag.

[0124] Specifically, the reducing agent in step 3 can be a carbonaceous reducing agent, which includes one or more components such as carbon powder and coal powder. The amount of carbonaceous reducing agent added is 1-3 times the theoretical carbon content (the theoretical carbon content is the ratio of the mass of effective carbon added to the mass of carbon required for the reduction of Fe2O3, P2O5, and MnO in the slag). Depending on the amount of carbonaceous reducing agent added, the total addition time of the carbonaceous reducing agent is controlled within the range of 5-15 minutes, and the temperature of the steel slag is controlled within the range of 1450℃-1650℃, maintaining the reduction time for 10 minutes to 1 hour to ensure that the slag is fully reduced.

[0125] Specifically, the injection rate of the carbonaceous reducing agent is 10-30 kg / (t·min), and the injection volume of the carbonaceous reducing agent is... Controlled by the following relation:

[0126] ;

[0127] in To process steel slag by weight, t;

[0128] The theoretical carbon content is generally 1-3.

[0129] To treat the mass fraction of P2O5 in the raw slag, %

[0130] The mass fraction of all iron oxides in the raw slag, converted to Fe2O3, is calculated as follows: %.

[0131] To treat the mass fraction of MnO in the raw slag, %

[0132] The mass fraction of carbon in a carbonaceous modifier is typically 90%-100%. It is a constant and can be obtained in advance by detecting the composition of the carbonaceous modifier.

[0133] It should be noted that in step 3, the reason for adding 1-3 times the theoretical amount of carbonaceous reducing agent to the modified slag is that adding too much carbonaceous reducing agent results in high material consumption and large carbon emissions; adding too little carbonaceous reducing agent results in insufficient reduction and low recovery rate of elements such as Fe.

[0134] It should be noted that in step 3, if the carbon powder blowing speed is too high, the carbon powder will be lost due to excessive burning; if the carbon powder blowing speed is too low, the mixing effect between the carbon powder and the molten pool will be poor, resulting in low reaction efficiency. Therefore, the carbon powder blowing speed should be 10-30 kg / (t·min).

[0135] It should be noted that in step 3, the total time for adding toner should be controlled within the range of 5-15 minutes. If the time for adding toner is too short, the reaction will be insufficient; if the time for adding toner is too long, the processing time will be long and the energy consumption will be high.

[0136] It should be noted that in step 3, the reduction time should be maintained for 10 minutes to 1 hour. If the reduction time is too short, the reduction will be insufficient; if the reduction time is too long, the energy consumption will be high.

[0137] It should be noted that in step 3, the reduction temperature is 1450℃-1650℃, the reduction time is 10min-1h, the reforming reduction furnace is rotated and tilted simultaneously, and carbonaceous reducing agent is sprayed by injection. The synergistic control of the above reduction conditions can promote the dissolution of phosphorus vapor after reduction into the molten iron and inhibit the overflow of phosphorus vapor after reduction, thereby further recovering valuable elements such as iron, phosphorus, and manganese.

[0138] Regarding step 4:

[0139] Specifically, in step 4, the first through hole 281 on the first slide plate 28 communicates with the steel tapping hole of the seat brick 27 and the third through hole 292 on the second slide plate 29, allowing molten iron to be discharged from the bottom. Then, the slag is discharged from the furnace opening of the reforming and reduction furnace 6, achieving effective steel-slag separation. It should be noted that when repeated discharge of molten iron is required, sand can be added using a sand-filling device after bottom steel tapping to prepare for subsequent steel tapping.

[0140] Specifically, after the slag reduction is completed in step 4, the slag is calmed in the reduction furnace for a certain period of time, which is 0-30 minutes, for example, 5 minutes, 10 minutes, 20 minutes, or 30 minutes. The molten iron discharged in step 4 contains valuable elements such as iron, phosphorus, and manganese.

[0141] It should be noted that in step 4, if the settling time is too short, the slag and iron separation will be incomplete; if the settling time is too long, the processing time will be long, the molten slag will solidify, and the slag and iron separation will be difficult.

[0142] Regarding step 5:

[0143] Specifically, the subsequent processing of the steel slag in step 5, after being introduced into the steel slag processing line, constitutes a steel slag resource utilization process. The specific steel slag processing line is the company's existing steel slag granulation process, such as hot quenching and air quenching. The subsequent resource utilization process involves online granulation of the molten slag, such as hot quenching and air quenching. After exiting the processing line, the steel slag undergoes multi-stage crushing and grinding to extract residual metallic iron. The tailings can then be directly used to produce mineral wool or meet the requirements for raw materials in building materials such as cement.

[0144] Specifically, the present invention provides a method for recovering valuable elements from steel slag, wherein the steel slag is derived from converter slag, electric furnace slag, molten iron pretreatment slag, and refining slag.

[0145] It should be noted that this invention provides a method for steel slag modification and recovery of valuable elements. This method enables the efficient recovery of resources such as phosphorus, iron, and manganese from steel slag and the resource utilization of the treated steel slag. This plays a crucial role in reducing land occupation and environmental pollution caused by the large-scale dumping of steel slag and in increasing the economic benefits of steel enterprises. Therefore, this invention has important reference and guiding significance for the efficient recycling of metallurgical industrial waste, especially large-scale stockpiling of steel slag.

[0146] The advantages of this invention lie in its efficient utilization of waste heat from steel slag and the energy generated during slag discharge stirring. It employs a synergistic process of slag melting and modification combined with controlled-temperature, deep-level modification within the reduction furnace to achieve steel slag composition conditioning. By using injection methods to perform temperature-controlled and carbothermic reduction treatments on the slag, this process can achieve phosphorus recovery rates exceeding 60%, iron recovery rates exceeding 90%, and manganese recovery rates of 10-80%. The treatment eliminates the influence of low-activity, refractory phases (RO phase) and weakly stable phases (f-CaO), reducing total iron content in the slag to below 3% and free calcium oxide to [missing information]. The concentration is below 0.1%, meeting the national standards for building materials such as cement. Furthermore, this method is simple, reliable, highly operable, and easy to implement, enabling efficient recovery of valuable elements from steel slag. This increases the resource utilization pathways for tailings, enhances the added value of steel slag, and significantly reduces energy consumption during slag treatment. It effectively solves the problems of high-value-added resource recovery and utilization of valuable elements in steel slag and the limitations imposed by the difficulty in large-scale resource utilization of steel slag in actual production. This lays the foundation for efficient recovery and resource utilization of valuable elements in slag, improving the economic benefits of steel enterprises and reducing environmental pollution.

[0147] The present invention differs from other steel slag resource utilization processes in the following ways: 1) Conventional steel slag resource utilization processes primarily focus on maximizing the elimination of f-CaO and f-MgO on the slag treatment line, followed by multi-stage crushing and magnetic separation to recover metallic iron or magnetic iron oxides. The remaining tailings are used as a small amount of admixture in cement and other building materials. Currently, there are no mature and reliable industrial cases that simultaneously achieve efficient recovery of valuable elements such as phosphorus, iron, and manganese from steel slag and facilitate complete resource utilization. This invention addresses the challenges of effectively recovering valuable elements from steel slag and the difficulty of large-scale resource utilization of tailings by proposing a new process that balances efficient recovery of valuable elements and tailings resource utilization. Specifically, it employs a synergistic approach of slag melting and upgrading with controlled temperature to economically and reliably achieve steel slag composition conditioning. The molten slag is heated and carbotherm-reduced using a spraying method to achieve continuous heating and effective reduction of the upgraded steel slag. Corresponding process control parameters and technical routes are also proposed. 2) This process proposes fully utilizing the waste heat of high-temperature steel slag to… The process scheme provides favorable thermodynamic and kinetic conditions for the initial melting and modification of steel slag, the use of injection heating and slag agitation in the molten pool for deep melting and modification of molten slag, and the use of injection reducing agent and slag agitation in the molten pool for carbothermic reduction treatment of molten slag. This provides favorable thermodynamic and kinetic conditions for the melting and modification and effective reduction of steel slag. 3) The process method provides process control for the initial melting and modification of steel slag, deep melting of molten slag, and carbothermic reduction treatment of molten slag. It proposes slag-iron separation conditions after melting and modification and carbothermic reduction, which improves the recovery rate of valuable elements such as phosphorus, iron, and manganese in slag and the utilization pathways of tailings. 4) The overall efficiency of the entire process is improved, enabling the efficient reduction and recovery of valuable elements such as phosphorus, iron, and manganese in steel slag. It also enables the treated tailings to meet the resource utilization requirements of building material raw materials, effectively solving the problems of unutilized residual heat of steel slag, difficulty in high-value-added resource recovery and utilization of valuable elements in slag, and difficulty in large-scale resource utilization of steel slag. Moreover, the method is simple to operate and easy to implement.

[0148] The following detailed description of preferred embodiments of the present invention illustrates the principles of the invention and is not intended to limit the scope of the invention.

[0149] Example 1

[0150] This method was used to treat steel slag from a dual-stage dephosphorization converter. The specific implementation process is as follows:

[0151] Step 1: During the slag dumping process, some of the high-temperature steel slag produced by the converter dephosphorization furnace is pre-treated by adding sand and gravel to the bottom of a special slag pot as a modifier. The amount of sand and gravel added is 11% of the amount of slag to be treated. The modification goal is to reduce the binary basicity of the steel slag to 1.0. The composition of the original slag and modified slag of the dephosphorization converter in this plant is shown in Table 1.

[0152] Step 2: After the preliminarily modified hot slag is poured into the modification and reduction furnace online, blast furnace gas is injected. The amount of blast furnace gas injected per ton of steel slag is 260 m³ / t based on the temperature of the hot steel slag. The slag temperature is controlled within the range of 1450℃-1650℃ to ensure that the slag is fully melted. At the same time, the slag in the molten pool is stirred to ensure that the molten pool is fully modified and mixed evenly.

[0153] Step 3: Raise the temperature of the molten slag to about 1500℃, and spray carbon powder into the molten slag. The amount of carbon powder sprayed is 15.5% of the amount of slag to be treated. The carbon powder spraying time is controlled at 10 min and the carbon powder spraying speed is 20 kg / (t•min). The entire spraying time and reaction time are maintained for 30 min to ensure that the molten slag is fully reduced.

[0154] In calculating the toner injection rate, It is 1.5. It is 4.34%. It is 25.54%. It is 4.55%. It is 99%.

[0155] Step 4: After the reduction is completed, the slag is calmed in the reduction furnace for 15 minutes to achieve stratification of slag and molten iron. Then, the reduced phosphorus-containing molten iron and slag are discharged separately to achieve effective separation of molten metal and slag. The composition of the molten metal and slag obtained after separation is shown in Table 2 and Table 3, respectively.

[0156] Step 5: After being processed by steel slag melting and modification and carbothermic reduction, the separated molten iron can be used as a metal material in smelting; the tailings in the tank are introduced into the slag treatment line for further processing. After the steel slag exiting the slag treatment line is crushed and ground in multiple stages, the residual iron is extracted. The tailings can be directly used to produce mineral wool or meet the requirements for raw materials for building materials such as cement, thus realizing the resource utilization of steel slag.

[0157] It should be noted that the constant in the formula for controlling the injection rate of carbonaceous reducing agent obtained from the experiment is... and They are 1.5% and 99% respectively.

[0158] It should be noted that, in order to reduce energy supply, carbonaceous reducing agent can be injected after the slag temperature rises to the point where the slag melts. Therefore, the deep melting and modification process and the carbothermic reduction process overlap.

[0159] Table 1. Target component mass fractions (%) of raw dephosphorized converter slag and molten modified slag from a certain plant.

[0160]

[0161] Table 2. Mass fraction of the metal liquid obtained after separation, %

[0162]

[0163] Table 3. Mass fraction of slag components obtained after separation, %

[0164]

[0165] according to Figure 7 As shown, 1 is the phosphorus-enriched phase, 2 is the RO phase, and 3 is the base phase. Figure 8 This is a photograph of the processed metal block. Figure 9 The image shows the slag sample obtained after processing, which demonstrates that valuable elements in the steel slag were effectively reduced.

[0166] In this embodiment, the iron recovery rate was 90.69%; the phosphorus recovery rate was 72.05%; the manganese recovery rate was 17.02%; and the TFe content in the slag was 0.81% and the f-CaO content was 0.09%.

[0167] Example 2

[0168] This method was used to treat electric arc furnace steel slag from a certain factory. The specific implementation process is as follows:

[0169] Step 1: A certain amount of mud and sand is added as a modifier to some of the high-temperature steel slag produced by electric furnace smelting during the slag dumping process along with the liquid slag flow. The addition is completed between 1 / 5 and 4 / 5 of the slag is discharged. The amount of mud and sand added is 31.96% of the slag volume processed. The modification target is to reduce the binary basicity of the steel slag to 1.0. The composition of the original slag and modified slag of the dephosphorization converter of this plant is shown in Table 4.

[0170] Step 2: After the preliminarily modified hot molten slag is poured online into a dedicated reduction furnace, 310m³ of molten slag is injected. 3 / t of blast furnace gas is used to reheat the slag, keeping the slag temperature within the range of 1450℃-1650℃, so that the slag is fully melted and the slag in the molten pool is stirred to ensure that the molten pool is fully modified and mixed evenly.

[0171] Step 3: Raise the temperature of the molten slag to about 1550℃, and then spray carbon powder into the molten slag. The amount of carbon powder sprayed is 11.3% of the amount of slag to be treated. The carbon powder is sprayed out in 8 minutes, and the carbon powder spraying speed is 15 kg / (t·min). The entire spraying time and reaction time are maintained for 40 minutes to ensure that the molten slag is fully reduced.

[0172] In calculating the toner injection rate, 99%, It is 1.61%. It was 21.59%. It is 1.82%. It is 1.5.

[0173] Step 4: After reduction, the slag is calmed in the reduction furnace for 20 minutes to achieve stratification of slag and molten iron. Then, the reduced phosphorus-containing molten iron and slag are discharged to achieve effective separation of molten metal and slag. The composition of the molten metal and slag obtained after separation is shown in Table 5 and Table 6, respectively.

[0174] Step 5: After being processed by steel slag melting and modification and carbothermic reduction, the separated molten iron can be used as a metal material in smelting; the tailings in the tank are introduced into the slag treatment line for further processing. After the steel slag exiting the slag treatment line is crushed and ground in multiple stages, the residual iron is extracted. The tailings can be directly used to produce mineral wool or meet the requirements for raw materials for building materials such as cement, thus realizing the resource utilization of steel slag.

[0175] It should be noted that the constant in the formula for controlling the injection rate of carbonaceous reducing agent obtained from the experiment is... and They are 1.5% and 99% respectively;

[0176] It should be noted that, in order to reduce energy supply, carbonaceous reducing agent can be injected after the slag temperature rises to the point where the slag melts. Therefore, the deep melting and modification process and the carbothermic reduction process overlap.

[0177] Table 4. Mass fraction of raw converter slag from a certain plant, %

[0178]

[0179] Table 5. Mass fraction of the metal liquid obtained after separation, %

[0180]

[0181] Table 6. Mass fraction of slag components obtained after separation, %

[0182]

[0183] according to Figure 10 As shown, 1 is the phosphorus-enriched phase, 2 is the RO phase, and 3 is the base phase. Figure 11 This is a photograph of the processed metal block. Figure 12 The image shows the slag sample obtained after processing, which demonstrates that valuable elements in the steel slag were effectively reduced.

[0184] In this embodiment, the iron recovery rate was 90.76%; the phosphorus recovery rate was 62.80%; the manganese recovery rate was 61.53%; the TFe content in the slag was 0.48%; and the f-CaO content was 0.08%.

[0185] Comparative Example 1

[0186] Compared with Example 1, this comparative example does not use the method provided by the present invention, but instead uses magnetic separation to recover magnetic metallic iron or iron oxides after cooling steel slag. However, only a small amount of metallic iron or iron oxides can be recovered from the slag, and the recovered steel slag cannot be used. The current practice is to discard or stockpile it.

[0187] Table 7. Target component mass fractions (%) of raw dephosphorized converter slag and molten modified slag from a certain plant.

[0188]

[0189] Table 8. Mass fraction of magnetic iron-containing substances obtained after separation, %

[0190]

[0191] Table 9. Mass fraction of TFe content in slag obtained after magnetic separation, %

[0192]

[0193] Table 10. Mass fraction of f-CaO in steel slag after magnetic separation and after modification, %

[0194]

[0195] It should be noted that although Embodiments 1 and 2 of this invention use converter slag and electric arc furnace slag as examples, this invention is not limited to these. The process for efficient recovery and resource utilization of valuable elements in steel slag, as described in this embodiment, is also applicable to other steel slags such as refining slag and pretreated hot metal slag produced during the iron and steel smelting process. Due to differences in slag type, composition, phase properties, and other parameters, the control conditions, such as the type of modifier, the amount of modifier added, the amount of reducing agent added, the control temperature, and the reduction time, also differ when using the slag melting modification and carbothermic reduction treatment process.

[0196] It is worth noting that the present invention is not limited to the converter slag in the above embodiments, but is also applicable to other steelmaking process slags generated in the steel production process.

[0197] It is worth noting that this invention provides formulas relating the amount of carbonaceous reducing agent injected during the carbothermic reduction process to the composition, weight, and theoretical carbon content of the steel slag, and gives key constants under specific experimental conditions in the examples. and The value of does not represent a constant in the control relationship involved in this invention. and It is a unique constant, while for the key constant and The determination of should be based on specific conditions such as the specific steel slag, process conditions, and related equipment parameters. This invention also provides constants. and Range of values.

[0198] It is worth noting that this invention emphasizes a process for economically and reliably conditioning steel slag composition by combining slag melting and conditioning with a controlled temperature regime. For example, it utilizes a powder-injected heating gun to heat the molten slag and perform carbothermic reduction treatment to achieve continuous heating and effective reduction of the slag. Based on this approach, this invention provides the control relationships for key parameters. Therefore, any process, control relationship, or control method obtained under the guidance of this approach should be covered within the scope of protection of this invention.

[0199] In summary, this invention provides a process for rationally utilizing the waste heat and slag stirring energy of steel slag, and achieving steel slag composition conditioning through a synergistic combination of initial melting and conditioning at the slag discharge stage and controlled deep conditioning at a reasonable temperature within the reduction furnace. The process utilizes injection to perform temperature-controlled carbothermic reduction treatment on the molten slag. After treatment, the phosphorus recovery rate in the slag can reach over 60%, the iron recovery rate over 90%, and the manganese recovery rate 10-80%. The treatment eliminates the influence of low-activity, refractory phases (RO phase) and weakly stable phases (f-CaO), reducing the total iron content in the slag to below 3%, and eliminating free oxides. The calcium content was reduced to below 0.1%, meeting the national standards for building materials such as cement. Furthermore, the method is simple, reliable, highly operable, and easy to implement, enabling the efficient recovery of valuable elements from steel slag. This increases the resource utilization pathways for tailings, enhances the added value of steel slag, and significantly reduces energy consumption during slag treatment. It effectively solves the problems of high-value-added resource recovery and utilization of valuable elements in steel slag and the limitations imposed by the difficulty in large-scale resource utilization of steel slag in actual production. This lays the foundation for the efficient recovery and resource utilization of valuable elements in slag, improving the economic benefits of steel enterprises and reducing environmental pollution.

[0200] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for steel slag modification and valuable element recovery, characterized in that, Including a rotating tilting system and a spray gun system, among which, The rotating and tilting system includes a modified reduction furnace and a tilting frame. The modified reduction furnace is arranged inside the tilting frame. The modified reduction furnace can rotate within the tilting frame about the central axis of the furnace body and tilt about the tilting axis of the tilting frame. The modified reduction furnace is connected to the tilting frame through a rotating support set inside the tilting frame. The modified reduction furnace can rotate 360° around the Y-axis under the support and drive of the rotating support. The spray gun system includes a powder spraying and heating gun and a rotary lifting mechanism. The powder spraying and heating gun is located on the upper side of the feeding port at the top of the modified reduction furnace. One end of the rotary lifting mechanism is connected to the powder spraying and heating gun, and the other end is connected to one side of the tilting shaft. The powder spraying and heating gun includes: a first pipe, which is a powder addition pipe; a second pipe, which surrounds the first pipe, which is a gas pipe; and a third pipe, which surrounds the second pipe, which is a gas-supporting pipe. The powder-injected heating lance adds powder to the steel slag during the modification and reduction process to modify and reduce it. The main function of the gas is to heat and replenish the temperature of the molten slag. The powder-injected heating lance adopts a high-speed design with a jet outlet velocity of >80m / s. The high-temperature and high-speed jet carries the modification powder to impact the slag surface, forming a high-temperature melting zone. The high-speed gas not only replenishes the heat but also stirs the molten pool, which is conducive to the modification reaction. The rotary lifting mechanism includes: The lifting arm is connected at one end to the powder spraying and heating gun and at the other end to the guide mechanism; The column has one end connected to the guide mechanism and the other end provided with a pivot hole, which is rotatably connected to the tilting shaft of the tilting frame. The steel tapping mechanism includes: A base brick is installed through the bottom of the reforming and reduction furnace, with a tapping hole in the middle; The first sliding plate is set on the underside of the seat brick and is slidably connected to the bottom of the modified reduction furnace. A first through hole is provided on the left side of the first sliding plate. The second slide plate is located below the first slide plate and is slidably connected to the first slide plate. The second slide plate has a second through hole on its left side and a third through hole in its middle. A sand filling device is located below the second through hole.

2. The apparatus according to claim 1, characterized in that, The rotating lifting mechanism also includes a chain, which is mounted on a column. Both ends of the chain are connected to a guide mechanism. Additionally, sprockets are mounted on the upper and lower sides of the column, and the chain is sleeved on the sprockets.

3. The apparatus according to claim 2, characterized in that, The column is provided with a pressure wheel and a drive wheel on its side, and the chain is sleeved on the pressure wheel and the drive wheel.

4. The apparatus according to claim 1, characterized in that, The sand filling device includes: A longitudinal extrusion device is disposed on the lower side of the second through hole and communicates with the second through hole; A transverse extrusion device is connected at one end to the longitudinal extrusion device, and a sand storage bin is provided on the upper side of the other end, which is connected to the transverse extrusion device.

5. The apparatus according to claim 1, characterized in that, When the first through hole is connected to the third through hole and the steel outlet hole of the seat brick, it is the steel outlet position; when the first through hole is connected to the second through hole, it is the sand filling position.

6. A method for modifying steel slag and recovering valuable elements, characterized in that, The apparatus described in any one of claims 1-5 comprises the following steps: Step 1: After the primary smelting furnace has finished tapping steel, during the high-temperature steel slag dumping process, a modifier is added in advance at the bottom of the modification and reduction furnace or along with the liquid slag flow, and the residual heat of the steel slag and the slag discharge power are used to melt and modify the slag. Step 2: After pouring the modified hot slag from Step 1 into the modification and reduction furnace online, gas is injected at the furnace opening to reheat the slag and simultaneously agitate the slag in the molten pool. Step 3: After the molten slag is heated in the reforming and reducing furnace, a reducing agent is injected into the reforming and reducing furnace opening; Step 4: After reduction, the molten slag pool is calmed to achieve stratification of molten slag and molten iron. Then, the molten iron is discharged from the bottom of the modified reduction furnace, and the slag is discharged from the furnace opening by flipping the furnace.

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