Metallurgical slag granulation and waste heat recovery system and method

Abstract

The invention provides a metallurgical slag granulation and waste heat recovery system and method. Comprising a granulation roller, a moving bed, a granulation cover, a cooling device, a fan, a waste heat boiler and a conveyor, and the granulation cover, the cooling device, the waste heat boiler and the fan are sequentially connected through flue gas pipelines to form a closed-loop flue gas passage. According to the method, water is not needed, full-dry granulation is achieved, latent heat and sensible heat of the whole process from the liquid state to the solid state of the slag are recycled, and the method has the advantages of being water-saving, energy-saving, environmentally friendly and high in equipment reliability and is suitable for resourceful treatment of high-temperature metallurgical slag such as blast furnace slag and steel slag.

Description

Technical Field

[0001] This invention relates to the field of metallurgical waste resource utilization technology, and in particular to a metallurgical slag granulation and waste heat recovery system and method. Background Technology

[0002] my country produces 400 to 500 million tons of metallurgical slag annually, including approximately 280 to 320 million tons of blast furnace slag and 120 to 180 million tons of steel slag. These metallurgical slags generally have temperatures above 1400℃ and contain a large amount of high-quality heat, possessing enormous potential for energy recovery.

[0003] Current technologies primarily employ water cooling, consuming enormous amounts of water resources annually. Furthermore, the high-quality heat contained in these high-temperature slags is not effectively utilized, resulting in significant heat waste. Summary of the Invention

[0004] In view of this, the present invention provides a system and method for metallurgical slag granulation and waste heat recovery. The purpose is to provide a more energy-efficient, environmentally friendly, and reliable system and method for metallurgical slag granulation and waste heat recovery.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A metallurgical slag granulation and waste heat recovery system includes: a granulation roller, a moving bed, a granulation hood, a cooling device, a blower, a waste heat boiler, and a conveyor, wherein the granulation hood, the cooling device, the waste heat boiler, and the blower are sequentially connected by flue gas pipes to form a closed-loop flue gas passage. The granulating roller is fixed in the middle of the granulating hood by bearings, and can rotate in both directions around its own axis. Its surface is evenly distributed with multiple roller teeth for crushing molten slag. The moving bed has a trough-shaped structure and is set below the granulating roller via a track. It can reciprocate along the track in the horizontal direction to receive high-temperature liquid slag and cooperate with the granulating roller to complete crushing and pushing during the granulation process. The granulation hood is a fully enclosed structure that can seal the granulation roller body and the moving bed body inside. The granulation hood is provided with an openable and closable door for the moving bed to enter and exit the granulation hood to complete the external slag receiving. The cooling device is a stationary hollow box, located below the moving bed corresponding to the middle of the granulation hood. The top is provided with a material discharge port and an air outlet that connect with the moving bed, and the bottom is provided with a material discharge port and an air inlet. The waste heat boiler receives high-temperature flue gas generated in the granulation hood and the cooling device through the flue gas pipeline, and obtains saturated steam and low-temperature flue gas through heat exchange. The low-temperature flue gas is transported to the granulation hood and the cooling device through the flue gas pipeline. The tail of the conveyor is located below the discharge port of the cooling device and is used to transfer the cooled solid granular slag.

[0006] Preferably, the axial direction of the granulating roller is arranged perpendicular to the length direction of the moving bed, and the linear velocity of the outer edge of the roller teeth is greater than the translational velocity of the moving bed.

[0007] Preferably, the movement directions of the granulating roller and the moving bed can be dynamically coordinated. Specifically, in the granulation stage, the rotation direction of the granulating roller is consistent with the translation direction of the moving bed to achieve uniform crushing; in the feeding stage, the rotation direction of the granulating roller is opposite to the translation direction of the moving bed, so that the solid slag gathers on both sides of the moving bed and is discharged into the cooling device through the discharge port.

[0008] Preferably, the cooling device is a vertical cooler or an annular cooler.

[0009] Preferably, the flue gas duct is equipped with a regulating valve, which is used to change the cooling air volume entering the granulation hood and the cooling device at different time periods.

[0010] Preferably, the track extends outside the granulation shroud.

[0011] This invention also proposes a method for granulation and waste heat recovery of metallurgical slag, comprising the following steps: Step 1: After the slag receiving is completed outside the granulation hood, the moving bed is entered into the granulation hood through the door of the granulation hood, and the door is closed to form a sealed space; Step 2: Control the granulation roller to rotate forward or backward and coordinate with the moving bed to reciprocate along the track. The granulation of liquid slag is achieved by the speed difference between the granulation roller and the moving bed. At the same time, the blower sends the low-temperature circulating air into the granulation hood through the flue gas pipe and blows it to the surface of the liquid slag at a certain flow rate through multiple flue gas branch pipes to cool the liquid slag into solid granular slag. Step 3: Adjust the rotation direction of the granulating roller to be opposite to the translational direction of the moving bed, and push the solid granular slag into the cooling device through the coordinated action of the two. Step 4: The blower sends the low-temperature circulating air to the bottom of the cooling device. The low-temperature circulating air penetrates upward through the solid granular slag to perform secondary cooling, further reducing the temperature of the solid granular slag. Step 5: The high-temperature flue gas after heat exchange in the granulation hood and the high-temperature flue gas after heat exchange in the cooling device enter the waste heat boiler through corresponding connected flue gas pipes to generate saturated steam and low-temperature flue gas. The low-temperature flue gas obtained after heat exchange is returned to the granulation hood and the cooling device by the fan and the flue gas pipes to complete the closed-loop circulation of flue gas. Step Six: The solid granular slag, after being cooled in the cooling device, is discharged through the discharge port to the conveyor and transferred to other areas by the conveyor.

[0012] The beneficial effects of this invention are as follows: This invention achieves green and efficient treatment and synergistic resource and energy recovery of metallurgical slag: It adopts a closed-loop flue gas path design of "granulation + cooling device + waste heat boiler + fan," cooling the slag throughout the process via air-cooled circulation, completely eliminating the large water consumption of traditional water quenching methods and avoiding related wastewater pollution problems. Simultaneously, the granulation hood is a fully enclosed structure, completely sealing off dust and flue gas during granulation and cooling processes. Combined with closed-loop flue gas circulation, it eliminates fugitive emissions, meets environmental protection requirements, and achieves harmless treatment of metallurgical slag. The granulation roller axis is arranged perpendicular to the length direction of the moving bed, with roller teeth evenly distributed on the surface, and the linear velocity of the outer edge of the roller teeth is greater than that of the moving bed. The moving bed's translational speed creates a reasonable speed difference, avoiding dead zones in crushing and preventing slag accumulation and agglomeration, ensuring the slag is fully and uniformly crushed. Simultaneously, during the granulation stage, the granulation rollers and moving bed move in the same direction to achieve uniform crushing, while during the feeding stage, their reverse movement causes solid slag particles to gather on both sides of the moving bed and fall precisely into the discharge port, preventing slag residue buildup inside the equipment and ensuring smooth subsequent heat exchange and conveying. Low-temperature flue gas cools the liquid slag inside the granulation hood and then further cools the phase-change solid slag in a cooling device. After the flue gas temperature rises, it enters the waste heat boiler, achieving centralized heat recovery and efficient heat exchange, generating saturated steam for external utilization, effectively recovering high-temperature waste heat. The high-quality heat contained in the molten slag reduces heat waste caused by traditional cooling methods, thus lowering the company's energy consumption. The track extends outside the granulation hood, allowing the moving bed to operate outside the hood to collect slag. Combined with the closable door of the granulation hood, slag collection is flexible and convenient, facilitating observation of the molten slag state and timely adjustment of the collection volume to avoid overload or underload, improving equipment operating efficiency and maintenance safety. The cooling device supports modular replacement of vertical coolers and annular coolers, allowing companies to flexibly choose according to their needs without reconstructing the entire system. Furthermore, regulating valves are installed on the flue gas ducts to adjust the amount of gas entering the granulation hood and cooling device at different times. The cooling airflow can adapt to the different characteristics of various slag types, further enhancing the system's adaptability to different working conditions. Through the coordinated action of the granulation roller and the moving bed, the granulation and pushing functions are integrated, eliminating the need for additional auxiliary equipment such as pushers and chutes. This simplifies the system structure, reduces equipment failure points, and the closed-loop flue gas circulation and airflow regulation design avoids problems such as flue gas pressure fluctuations caused by excessive airflow or insufficient cooling and slag sticking to the wall caused by insufficient airflow, ensuring long-term continuous and stable operation of the system. The cooled solid granular slag is directly transferred by the conveyor without the need for additional transfer equipment, avoiding secondary heating or scattering and contamination of the slag. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the metallurgical slag granulation and waste heat recovery system of the present invention; Figure 2 This is a flowchart of the metallurgical slag granulation and waste heat recovery method of the present invention.

[0014] Reference numerals: 1: Granulating roller, 2: Moving bed, 3: Granulating hood, 4: Cooling device, 5: Fan, 6: Waste heat boiler, 7: Flue gas duct, 8: Conveyor, 9: Track, 10: Gate. Detailed Implementation

[0015] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0017] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0018] like Figure 1As shown, the metallurgical slag granulation and waste heat recovery system of the present invention mainly includes a granulating roller 1, a moving bed 2, a granulation hood 3, a cooling device 4, a blower 5, a waste heat boiler 6, and a conveyor 8. The granulation hood 3, cooling device 4, waste heat boiler 6, and blower 5 are sequentially connected by flue gas pipes 7 to form a closed-loop flue gas passage. The granulating roller 1 is fixed to the center of the granulation hood 3 by bearings and can rotate in both directions around its own axis. Its surface is evenly distributed with multiple roller teeth for crushing slag. The moving bed 2 has a trough-shaped structure and is positioned below the granulating roller 1 via a track 9, allowing it to move horizontally along the track. The conveyor belt 9 moves reciprocally to receive high-temperature liquid slag and, during the granulation process, works in conjunction with the granulating roller 1 to complete crushing and feeding. The granulation hood 3 is a fully enclosed structure that seals the main body of the granulating roller 1 and the main body of the moving bed 2 inside. The granulation hood 3 is equipped with an openable and closable door 10 for the moving bed 2 to enter and exit the granulation hood 3 to complete external slag reception. The cooling device 4 is a stationary hollow box, located below the moving bed 2 in the middle of the granulation hood 3. The top is equipped with a discharge port and an air outlet that connect with the moving bed 2, and the bottom is equipped with a discharge port and an air inlet. The waste heat boiler 6 receives the waste heat from the granulation hood 3 and the cooling device 4 through the flue gas pipe 7. The high-temperature flue gas generated in device 4 is cooled and converted into saturated steam and low-temperature flue gas through heat exchange. The low-temperature flue gas is then transported to granulation hood 3 and cooling device 4 via flue gas pipe 7. The tail of conveyor 8 is located below the discharge port of cooling device 4 and is used to transfer the cooled solid granular slag. This setup achieves full air-cooled circulating cooling through a closed-loop flue gas path design of "granulation + cooling device 4 + waste heat boiler 6 + fan 5," eliminating the water consumption of traditional water quenching methods and avoiding dust-containing wastewater pollution. At the same time, the fully enclosed structure of granulation hood 3 completely seals the dust and flue gas during the granulation and cooling process, preventing dust from entering the granulation and cooling process. There are absolutely no organized emissions; the granulation roller 1 has uniformly distributed roller teeth on its surface, and with its forward and reverse rotation function, it can crush high-temperature liquid slag. The trough-shaped moving bed 2 can stably support the high-temperature liquid slag, avoiding equipment damage and safety hazards caused by slag splashing; the low-temperature flue gas, after passing through the granulation process and the cooling device 4 for heat exchange, converges into the waste heat boiler 6 to achieve heat recovery and generate steam, effectively recovering the heat contained in the slag and reducing the company's energy consumption; the bottom discharge port of the cooling device 4 is precisely connected to the conveyor 8, and the cooled solid granular slag can be directly transferred without additional transfer equipment, avoiding secondary heating of the slag or scattering and pollution.

[0019] like Figure 1As shown, the axial direction of the granulating roller 1 is arranged perpendicular to the length direction of the moving bed 2, and the linear velocity of the outer edge of the roller teeth is greater than the translational velocity of the moving bed 2. Specifically, all equipment in this technical solution adopts frequency conversion speed regulation and follows the principle that the linear velocity of the outer edge of the roller teeth is greater than the translational velocity of the moving bed 2. The ratio of the linear velocity of the outer edge of the roller teeth to the translational velocity of the moving bed 2 can be determined according to the actual use. This setting can make the granulation effect more uniform. The axial direction of the granulating roller 1 is arranged perpendicular to the length direction of the moving bed 2, so that the roller teeth can fully cover the tank area of ​​the moving bed 2, avoiding crushing dead corners. The linear velocity of the outer edge of the roller teeth is greater than the translational velocity of the moving bed 2, forming a reasonable speed difference, which not only ensures that the molten slag is fully sheared and crushed, but also prevents the molten slag from accumulating and agglomerating on the moving bed 2. At the same time, through speed difference optimization, the hard contact impact between the roller teeth and the molten slag is reduced, reducing equipment wear.

[0020] like Figure 1 As shown, the movement directions of the granulating roller 1 and the moving bed 2 can be dynamically coordinated. Specifically, in the granulation stage, the rotation direction of the granulating roller 1 is consistent with the translation direction of the moving bed 2 to achieve uniform crushing; in the feeding stage, the rotation direction of the granulating roller 1 is opposite to the translation direction of the moving bed 2, causing the solid slag to gather on both sides of the moving bed 2 and be discharged into the cooling device 4 through the discharge port. This setting integrates the functions of granulation and feeding. In the granulation stage, the granulating roller 1 and the moving bed 2 move in the same direction to achieve uniform crushing of the molten slag, and in the feeding stage, they move in opposite directions to achieve slag aggregation and discharge. There is no need to set up additional auxiliary equipment such as feeders and chutes, which simplifies the system structure. At the same time, when moving in opposite directions, the pushing of the slag by the granulating roller 1 and the translation of the moving bed 2 form a synergistic force, causing the solid granular slag to gather on both sides of the moving bed 2 and fall accurately into the discharge port, avoiding the decrease in heat exchange efficiency or equipment blockage caused by slag accumulation inside the equipment.

[0021] like Figure 1 As shown, cooling device 4 is either a vertical cooler or an annular cooler. This configuration makes the technical solution more adaptable. Cooling device 4 supports modular replacement of vertical coolers and annular coolers, allowing enterprises to flexibly choose according to their actual needs without reconstructing the entire system. The vertical cooler is a stationary hollow box with air vents at the bottom, allowing circulating air to penetrate upwards through the material layer to cool the slag. The annular cooler is an optional cooling method. Both devices can effectively reduce the temperature of solid granular slag, meeting the requirements for subsequent transportation and reuse.

[0022] like Figure 1As shown, a regulating valve is installed on the flue gas duct 7. The regulating valve is used to change the cooling air volume entering the granulation hood 3 and the cooling device 4 at different time periods. Specifically, when the liquid slag is being cooled on the moving bed 2, the regulating valve on the flue gas duct 7 connected to the granulation hood 3 is opened, allowing low-temperature flue gas to enter the granulation hood 3 to cool the liquid slag. The cooling air volume continues until the solid granulated slag falls into the cooling device 4, at which point the corresponding regulating valve is closed to stop the air supply. When the cooling device 4 contains solid granulated slag and is not in the discharge process, the regulating valve on the flue gas duct 7 connected to the cooling device 4 is opened, allowing low-temperature flue gas to enter the cooling device 4. The solid granular slag is subjected to secondary cooling in the cooling device 4 until it needs to be discharged from the cooling device 4 to the conveyor 8. At this point, the corresponding regulating valve is closed to stop the air supply. The regulating valve can independently control the cooling air volume entering the granulation hood 3 and the cooling device 4. During the granulation stage, the air volume can be increased to quickly cool the liquid molten slag to a solid state and avoid sticking to the rollers. During the cooling stage, the air volume can be dynamically adjusted according to the slag temperature to balance the cooling efficiency and waste heat recovery effect. At the same time, it can adapt to the differences in characteristics of different slag types and avoid problems such as flue gas pressure fluctuations caused by excessive air volume or insufficient cooling and slag sticking to the wall caused by insufficient air volume, thereby improving the stability of system operation.

[0023] like Figure 1 As shown, track 9 extends outside the granulation hood 3. This arrangement allows the moving bed 2 to run outside the hood to complete slag collection. Combined with the openable and closable door 10 of the granulation hood 3, the slag collection operation is flexible and convenient. At the same time, when collecting slag outside the hood, the granulation hood 3 can remain closed for internal maintenance, realizing parallel slag collection and maintenance. It also facilitates observation of the molten slag status, timely adjustment of the slag collection amount, avoidance of overload or underload, and improvement of equipment utilization.

[0024] like Figure 2 As shown in the figure, this embodiment provides a method for metallurgical slag granulation and waste heat recovery, the specific steps of which are as follows: Step 1: After the slag is collected outside the granulation hood 3, the moving bed 2 enters the granulation hood 3 through the door 10 of the granulation hood 3, and the door 10 is closed to form a sealed space. Step 2: Control the granulation roller 1 to rotate forward or backward and coordinate with the moving bed 2 to move back and forth along the track 9. The granulation of liquid slag is achieved by the speed difference between the granulation roller 1 and the moving bed 2. At the same time, the blower 5 sends low temperature circulating air into the granulation hood 3 through the flue gas pipe 7 and blows it to the surface of the liquid slag at a certain flow rate through multiple flue gas branch pipes to cool the liquid slag into solid granular slag. Step 3: Adjust the rotation direction of the granulating roller 1 to be opposite to the translational direction of the moving bed 2, and push the solid granular slag into the cooling device 4 through the coordinated action of the two. Step 4: The blower 5 sends low-temperature circulating air to the bottom of the cooling device 4. The low-temperature circulating air penetrates the solid granular slag upwards to perform secondary cooling (cooling it to about 200°C), further reducing the temperature of the solid granular slag. Step 5: The high-temperature flue gas after heat exchange in the granulation hood 3 and the high-temperature flue gas after heat exchange in the cooling device 4 enter the waste heat boiler 6 through the corresponding connected flue gas pipes 7 to generate saturated steam and low-temperature flue gas. The low-temperature flue gas obtained after heat exchange is returned to the granulation hood 3 and the cooling device 4 by the fan 5 and the flue gas pipes 7 to complete the closed-loop circulation of flue gas. Step 6: After the solid granular slag has been cooled in the cooling device 4, it is discharged through the discharge port to the conveyor 8, and then transferred to other areas by the conveyor 8.

[0025] The above steps are performed throughout the entire metallurgical slag processing; therefore, there is no necessary sequential order among the steps. For example, while performing step one after feeding a new batch of molten steel slag, step five regarding the previous batch of molten steel slag may also be performed simultaneously in the cooling device.

[0026] The specific operating principle is as follows: After the slag is collected outside the granulation hood, the moving bed enters the granulation hood through the hood's main door, which is then closed to create a sealed space. The granulation rollers are controlled to rotate forward or backward in coordination with the moving bed's reciprocating motion along the track. The speed difference between the granulation rollers and the moving bed breaks down and granulates the molten slag. Simultaneously, a blower delivers low-temperature circulating air through flue gas ducts into the granulation hood and blows it onto the surface of the molten slag at a certain flow rate through multiple flue gas branch pipes, cooling the molten slag into solid granular slag. The rotation direction of the granulation rollers is adjusted to be opposite to the direction of the moving bed's translation; through their coordinated action, the solid granular slag is pushed into the cooling device. Low-temperature circulating air is sent to the bottom of the cooling device by a fan. The low-temperature circulating air penetrates the solid granular slag upwards to cool it a second time, further reducing the temperature of the solid granular slag. The high-temperature flue gas after heat exchange in the granulation hood and the high-temperature flue gas after heat exchange in the cooling device enter the waste heat boiler through corresponding connected flue gas pipes to generate saturated steam and low-temperature flue gas. The low-temperature flue gas obtained after heat exchange is returned to the granulation hood and cooling device by the fan and flue gas pipes to complete the closed-loop circulation of flue gas. The solid granular slag that has been cooled in the cooling device is discharged through the discharge port to the conveyor and transferred to other areas by the conveyor.

[0027] Parameter description: All parameter values ​​mentioned in this manual are not subjective assumptions, but rather a comprehensive result of the application scenario's security / efficiency requirements, industry standards and specifications, and industry practice experience thresholds. In actual applications, the parameters will be fine-tuned according to the relevant scenarios.

[0028] The components provided in this invention are only for use in accordance with the structural features of the product. The product will be adjusted and modified after purchase to better match and conform to the technical solution of this invention. It is an optimal application of this technical solution. The product model can be replaced and modified according to the required technical parameters. It is well known to those skilled in the art. Therefore, those skilled in the art can clearly obtain the corresponding usage effect through the technical solution provided in this invention.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A metallurgical slag granulation and waste heat recovery system, characterized in that, include: The granulation roller, moving bed, granulation hood, cooling device, fan, waste heat boiler and conveyor are connected in sequence through flue gas pipes to form a closed-loop flue gas passage. The granulating roller is fixed in the middle of the granulating hood by bearings, and can rotate in both directions around its own axis. Its surface is evenly distributed with multiple roller teeth for crushing molten slag. The moving bed has a trough-shaped structure and is set below the granulating roller via a track. It can reciprocate along the track in the horizontal direction to receive high-temperature liquid slag and cooperate with the granulating roller to complete crushing and pushing during the granulation process. The granulation hood is a fully enclosed structure that can seal the granulation roller body and the moving bed body inside. The granulation hood is provided with an openable and closable door for the moving bed to enter and exit the granulation hood to complete the external slag receiving. The cooling device is a stationary hollow box, located below the moving bed corresponding to the middle of the granulation hood. The top is provided with a material discharge port and an air outlet that connect with the moving bed, and the bottom is provided with a material discharge port and an air inlet. The waste heat boiler receives high-temperature flue gas generated in the granulation hood and the cooling device through the flue gas pipeline, and obtains saturated steam and low-temperature flue gas through heat exchange. The low-temperature flue gas is transported to the granulation hood and the cooling device through the flue gas pipeline. The tail of the conveyor is located below the discharge port of the cooling device and is used to transfer the cooled solid granular slag.

2. The metallurgical slag granulation and waste heat recovery system according to claim 1, characterized in that, The axial direction of the granulating roller is arranged perpendicular to the length direction of the moving bed, and the linear velocity of the outer edge of the roller teeth is greater than the translational velocity of the moving bed.

3. The metallurgical slag granulation and waste heat recovery system according to claim 1, characterized in that, The movement directions of the granulating roller and the moving bed can be dynamically coordinated. Specifically, during the granulation stage, the rotation direction of the granulating roller is consistent with the translation direction of the moving bed to achieve uniform crushing. During the feeding stage, the rotation direction of the granulating roller is opposite to the translation direction of the moving bed, causing the solid slag to gather on both sides of the moving bed and be discharged into the cooling device through the discharge port.

4. The metallurgical slag granulation and waste heat recovery system according to claim 1, characterized in that, The cooling device is a vertical cooler or an annular cooler.

5. The metallurgical slag granulation and waste heat recovery system according to claim 1, characterized in that, The flue gas duct is equipped with a regulating valve, which is used to change the cooling air volume entering the granulation hood and the cooling device at different time periods.

6. The metallurgical slag granulation and waste heat recovery system according to claim 1, characterized in that, The track extends outside the granulation shroud.

7. A method for granulation and waste heat recovery of metallurgical slag as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: After the slag receiving is completed outside the granulation hood, the moving bed is entered into the granulation hood through the door of the granulation hood, and the door is closed to form a sealed space; Step 2: Control the granulation roller to rotate forward or backward and coordinate with the moving bed to reciprocate along the track. The granulation of liquid slag is achieved by the speed difference between the granulation roller and the moving bed. At the same time, the blower sends the low-temperature circulating air into the granulation hood through the flue gas pipe and blows it to the surface of the liquid slag at a certain flow rate through multiple flue gas branch pipes to cool the liquid slag into solid granular slag. Step 3: Adjust the rotation direction of the granulating roller to be opposite to the translational direction of the moving bed, and push the solid granular slag into the cooling device through the coordinated action of the two. Step 4: The blower sends the low-temperature circulating air to the bottom of the cooling device. The low-temperature circulating air penetrates upward through the solid granular slag to perform secondary cooling, further reducing the temperature of the solid granular slag. Step 5: The high-temperature flue gas after heat exchange in the granulation hood and the high-temperature flue gas after heat exchange in the cooling device enter the waste heat boiler through corresponding connected flue gas pipes to generate saturated steam and low-temperature flue gas. The low-temperature flue gas obtained after heat exchange is returned to the granulation hood and the cooling device by the fan and the flue gas pipes to complete the closed-loop circulation of flue gas. Step Six: The solid granular slag, after being cooled in the cooling device, is discharged through the discharge port to the conveyor and transported to other areas by the conveyor.

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