A high-temperature solid bulk material waste heat direct recovery system applied to high-temperature steel slag

Abstract

This utility model discloses a high-temperature solid bulk material waste heat direct recovery system for high-temperature steel slag, comprising: a discharge tank for receiving and temporarily storing high-temperature molten steel slag discharged from a metallurgical furnace; a crushing and screening device including a crusher and a conveying and screening mechanism, wherein the inlet of the crusher is connected to the outlet of the discharge tank, and the inlet of the conveying and screening mechanism is connected to the outlet of the crusher; a high-temperature solid bulk material waste heat direct recovery device, wherein the inlet of the high-temperature solid bulk material waste heat direct recovery device is connected to the outlet of the conveying and screening device; and a tail-end treatment device including a hot quenching tank, wherein the inlet of the hot quenching tank is connected to the outlet of the high-temperature solid bulk material waste heat direct recovery device. This utility model realizes the staged cooling of high-temperature steel slag to achieve energy cascade utilization, greatly improves steam quality, reduces cooling time, and provides very favorable conditions for the subsequent resource utilization of steel slag.

Description

Technical Field

[0001] This utility model relates to the field of high-temperature steel slag waste heat recovery technology, specifically to a high-temperature solid bulk waste heat direct recovery system applied to high-temperature steel slag. Background Technology

[0002] As a major carbon emitter, the steel industry accounts for 18% of the country's total carbon emissions, ranking second among all industrial categories. Therefore, achieving low-carbonization has become an important measure to promote the leapfrog and high-quality development of the steel industry.

[0003] Existing methods for recovering waste heat from metallurgical slag mainly include: a) Dry granulation waste heat recovery technology, which uses granulation devices such as rotary discs or drums to break molten metallurgical slag into fine metallurgical slag particles under mechanical force. Air and high-temperature slag particles exchange heat in a fluidized bed (or fixed bed, moving bed), and the heated air drives a waste heat boiler to generate steam for power generation; b) Wind tunnel quenching method, which uses high-pressure air to directly impact the metallurgical slag stream, breaking it up, while air exchanges heat with the broken slag particles; c) Hot simmering method.

[0004] However, the above-mentioned process methods have the following drawbacks: (1) The temperature of the metallurgical slag discharge is high and it contains a lot of energy. The specific heat of air is low, about Cg=1.0kj / (kg*℃). The heat recovery of metallurgical slag by using air as the heat exchange medium will inevitably result in a large air-slag ratio, which requires a large air volume fan to match it; (2) The metallurgical slag particles obtained by dry granulation waste heat recovery are small. The porosity of slag particles in fixed bed, moving bed and fluidized bed is low, resulting in high air pressure and increasing the power consumption of waste heat recovery system; (3) The fine metallurgical slag particles are blown up and carried in hot air, which requires the addition of dust removal equipment, thereby increasing the construction cost and operating cost; (4) The air quenching method is affected by the oxidation of iron elements, which seriously affects iron recovery and has poor economic efficiency; (5) The hot slag cooling time is long and the waste heat recovery effect of steel slag in the low temperature section is poor. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature solid bulk material waste heat direct recovery system for high-temperature steel slag, in order to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, this utility model provides a high-temperature solid bulk material waste heat direct recovery system applied to high-temperature steel slag, which includes: A slag discharge tank is used to receive and temporarily store high-temperature molten steel slag discharged from a metallurgical furnace. A crushing and screening device, comprising a crusher and a conveying and screening mechanism, wherein the feed inlet of the crusher is connected to the discharge outlet of the discharge tank, and the feed inlet of the conveying and screening mechanism is connected to the discharge outlet of the crusher. A high-temperature solid bulk waste heat direct recovery device, wherein the inlet of the high-temperature solid bulk waste heat direct recovery device is connected to the outlet of the conveying and screening mechanism; The tail-end processing device includes a hot sealing tank, the inlet of which is connected to the outlet of the high-temperature solid bulk waste heat direct recovery device.

[0007] Furthermore, the crusher includes a first crusher and a second crusher, the feed inlet of the first crusher is connected to the discharge outlet of the discharge tank, the feed inlet of the second crusher is connected to the discharge outlet of the first crusher, and the discharge outlet of the second crusher is connected to the feed inlet of the conveying and screening mechanism.

[0008] Furthermore, the crushing and screening device also includes a buffer chamber, the inlet and outlet of which are connected to the outlet of the first crusher and the inlet of the second crusher, respectively.

[0009] Furthermore, the conveying and screening mechanism includes a lifting conveyor and a screening machine. The feed inlet of the lifting conveyor is connected to the discharge outlet of the second crusher, the feed inlet of the screening machine is connected to the discharge outlet of the lifting conveyor, and the discharge outlet of the screening machine is connected to the feed inlet of the high-temperature solid bulk waste heat direct recovery device.

[0010] Furthermore, the lifting conveyor includes a lifting bucket and a lifting machine, wherein the lifting machine is used to control the lifting bucket to move up and down.

[0011] Furthermore, the lifting conveyor also includes a feeding hopper, which is disposed above the lifting bucket and has its inlet connected to the outlet of the second crusher, and its outlet connected to the inlet of the lifting bucket.

[0012] Furthermore, the tail-end processing device also includes a rod mill and a magnetic separator. The feed inlet of the rod mill is connected to the discharge outlet of the hot quenching tank through a conveying device for crushing the steel slag after hot quenching. The magnetic separator is used to magnetically separate and recover metallic iron from the crushed steel slag.

[0013] The beneficial effects of this invention are as follows: This invention perfectly combines solid-solid heat exchange technology with hot quenching process, allowing high-temperature solid steel slag particles to directly exchange heat with the medium inside the heat exchange tube, avoiding the huge heat loss from air and secondary heat exchange tubes, and enabling more efficient recovery of waste heat from high-temperature steel slag. Furthermore, without the introduction of intermediate media, there are no new sources of pollution, and the absence of power equipment such as fans effectively reduces construction and operating costs. Simultaneously, after recovering waste heat from the steel slag through the high-temperature solid bulk waste heat recovery device, it enters the hot quenching tank to effectively dissolve the free calcium oxide, allowing the steel slag to be further pulverized and crushed. The rapid cooling and waste heat recovery of the high-temperature solid-solid heat exchange section combined with the self-pulverization effect of the low-temperature hot quenching section improves the problem of poor waste heat recovery in the low-temperature section, enhancing the integrity and effectiveness of waste heat recovery. This invention enables the recovery of thermal energy from high-temperature steel slag in the high-temperature stage through a direct waste heat recovery device for high-temperature solid bulk materials, and the segmented utilization of the low-temperature stage through hot slag melting in a hot slag-making tank. This shortens the cooling time of the high-temperature steel slag and cleverly utilizes the most valuable low-temperature waste heat in the pre-treatment stage of steel slag resource utilization, thereby maximizing energy efficiency. Attached Figure Description

[0014] Figure 1 This is a structural schematic diagram of an embodiment of the present utility model.

[0015] The components include: 1. Feeding tank; 2. Crushing and screening device; 3. High-temperature solid bulk material waste heat direct recovery device; 4. Tail-end treatment device.

[0016] 21. First crusher; 22. Second crusher; 23. Conveying and screening mechanism; 24. Buffer silo; 41. Hot sluice box.

[0017] 231. Elevating bucket; 232. Elevator; 233. Feeding bucket. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only one embodiment of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments.

[0020] In the following description, references to "an embodiment," "an embodiment," "an example," "example," etc., indicate that the described embodiment or example may include a particular feature, structure, characteristic, property, element, or limitation, but not every embodiment or example necessarily includes that particular feature, structure, characteristic, property, element, or limitation. Furthermore, the repeated use of the phrase "an embodiment according to this application," while possibly referring to the same embodiment, does not necessarily refer to the same embodiment.

[0021] like Figure 1 As shown, this utility model discloses a high-temperature solid bulk material waste heat direct recovery system applied to high-temperature steel slag, which includes: The discharge tank 1 is used to receive and temporarily store the high-temperature molten steel slag discharged from the metallurgical furnace. This device plays the role of receiving, temporarily storing and buffering, which solves the contradiction between the periodic slag discharge in metallurgical production and the continuous downstream processing, and provides the initial conditions for the stable operation of the entire system.

[0022] The crushing and screening device 2 includes a crusher and a conveying and screening mechanism 23. The feed inlet of the crusher is connected to the discharge outlet of the discharge tank 1, and the feed inlet of the conveying and screening mechanism 23 is connected to the discharge outlet of the crusher. The crushing and screening device 2 includes a first crusher 21, a second crusher 22, and a conveying and screening mechanism 23. The feed inlet of the first crusher 21 is connected to the discharge outlet of the discharge tank 1, the feed inlet of the second crusher 22 is connected to the discharge outlet of the first crusher 21, and the feed inlet of the conveying and screening mechanism 23 is connected to the discharge outlet of the second crusher 22. High-temperature molten slag flows steadily into the crusher from the discharge tank 1. Here, large pieces of slag are mechanically crushed. This process is not only to reduce particle size, but more importantly, to accelerate the phase transition of the slag from liquid to solid by increasing the surface area and mechanical disturbance, thus laying the foundation for subsequent solid-state heat exchange.

[0023] After being crushed, the steel slag enters the conveying and screening mechanism 23 from the discharge port of the crusher 22 for screening. This ensures that only steel slag particles that meet the particle size requirements enter the next stage, while oversized particles are returned for re-crushing. This guarantees the uniformity of the material entering the heat exchange device, thereby ensuring the stability of the heat exchange efficiency.

[0024] The high-temperature solid bulk material waste heat direct recovery device 3 has its inlet connected to the outlet of the conveying and screening mechanism 23. This device directly couples high-temperature steel slag cooling and waste heat recovery; that is, within this device, the high-temperature steel slag is in direct contact with heat exchange tubes filled with water and steam as the medium. Heat is transferred directly from the high-temperature steel slag to the heat exchange medium inside the heat exchange tubes through heat conduction and radiation between the solid and solid components. This heats the slag into high-grade superheated steam for power generation or other industrial applications.

[0025] Because no air is introduced as a cooling medium, there is no secondary heat exchange, significantly improving the residual heat recovery efficiency to over 80%, which is more than 20% higher than the efficiency of traditional air cooling followed by heat recovery. Furthermore, since no intermediate medium is introduced, no new pollution sources are generated, resulting in extremely high environmental protection characteristics. Additionally, no power equipment such as fans is required. If air cooling were used, the air-to-slag ratio would be high, necessitating large-volume fans; the power consumption of an air-cooled system per ton of steel slag would be 9-10 kWh. This solution effectively reduces construction and operating costs.

[0026] The tail-end processing device 4 includes a hot quenching tank 41, whose inlet is connected to the outlet of the high-temperature solid bulk waste heat direct recovery device 3. The high-temperature solid bulk waste heat direct recovery device 3 cools the high-temperature steel slag to a suitable temperature, allowing it to cool rapidly before entering the hot quenching tank 41 for hot quenching. Its core principle is to utilize the steel slag's own waste heat to react with water, causing the slag to self-pulverize and further refine its physical particle size. This transforms it from a hazardous industrial solid waste into a high-quality primary raw material that is stable and easily applied in subsequent magnetic separation and building materials.

[0027] Traditional hot-quenching methods require processing steel slag cooled from thousands of degrees Celsius, a process that is extremely lengthy. In contrast, this system utilizes a high-temperature solid waste heat recovery device 3 to handle the most time-consuming high-temperature cooling stage with high efficiency, shortening the overall system processing cycle. Furthermore, because contact with air is avoided during the high-temperature stage (solid-to-solid heat exchange without air), minimal oxidation of the metallic iron is achieved, maintaining its high grade. The steel slag in the low-temperature stage undergoes hot-quenching treatment in the hot-quenching tank 41, effectively dissolving free calcium oxide and allowing for further pulverization and crushing of the slag, providing highly favorable conditions for subsequent resource utilization.

[0028] This invention perfectly combines high-temperature solid bulk material waste heat recovery technology with a hot quenching process. High-temperature solid steel slag particles directly exchange heat with the medium inside the heat exchange tubes, avoiding significant heat loss from air and secondary heat exchangers, thus enabling more efficient recovery of waste heat from the high-temperature steel slag. Furthermore, without introducing intermediate media, there are no new pollution sources, and the absence of power equipment such as fans effectively reduces construction and operating costs. Simultaneously, after the waste heat is recovered from the steel slag through the high-temperature solid bulk material waste heat recovery device 3, it enters the hot quenching tank 41 to effectively dissolve the free calcium oxide, allowing the steel slag to be further pulverized and crushed. The rapid cooling and waste heat recovery from solid-solid heat exchange in the high-temperature section, combined with the self-pulverization effect of the hot quenching in the low-temperature section, improves the poor waste heat recovery effect in the low-temperature section, enhancing the integrity and effectiveness of waste heat recovery. This invention enables the thermal energy of high-temperature steel slag to be recovered in the high-temperature stage through the high-temperature solid bulk material waste heat recovery device 3, and in the low-temperature stage through the segmented utilization of slag by the hot slag melting tank 41. This shortens the cooling time of high-temperature steel slag and cleverly uses the most difficult-to-utilize low-temperature waste heat in the most valuable steel slag resource pretreatment stage, thereby maximizing energy efficiency.

[0029] In one embodiment, the crusher includes a first crusher 21 and a second crusher 22. The feed inlet of the first crusher 21 is connected to the discharge outlet of the discharge tank 1, the feed inlet of the second crusher 22 is connected to the discharge outlet of the first crusher 21, and the discharge outlet of the second crusher 22 is connected to the feed inlet of the conveying and screening mechanism 23.

[0030] Because the slag discharge temperature is high, exceeding 1400℃ even at the crushing zone, a primary crushing process is performed at the front end to address the liquid-solid phase change issue. The core function of the first crusher 21 is to perform "liquid-solid phase change" crushing, breaking large pieces of slag, which may still be molten inside, into smaller particles, allowing them to cool rapidly and completely solidify. This is a prerequisite for subsequent efficient and stable solid-solid heat exchange.

[0031] The second crusher 22 further crushes the solid steel slag after the initial crushing. Its purpose is to crush the steel slag to the optimal particle size range suitable for solid-solid heat exchange, ensuring that it has a sufficiently large specific surface area to facilitate rapid heat exchange, and that there are enough gaps between the particles to allow them to flow and contact smoothly between the heat exchange tubes filled with heat exchange medium.

[0032] In one embodiment, the crushing and screening device 2 further includes a buffer chamber 24, the inlet and outlet of which are connected to the outlet of the first crusher 21 and the inlet of the second crusher 22, respectively.

[0033] Because the slag supply fluctuates with the converter smelting cycle, a buffer bin 24 needs to be set up after the initial crushing to store the high-temperature slag after the initial crushing, so that the periodically fluctuating material is transformed into a continuous material, ensuring that the second crusher 22 can work continuously and stably, thus better adapting to the high-temperature solid bulk material waste heat direct recovery device 3.

[0034] In one embodiment, the conveying and screening mechanism 23 includes a lifting conveyor and a screening machine. The feed inlet of the lifting conveyor is connected to the discharge outlet of the second crusher 22, the feed inlet of the screening machine is connected to the discharge outlet of the lifting conveyor, and the discharge outlet of the screening machine is connected to the feed inlet of the high-temperature solid bulk waste heat direct recovery device 3.

[0035] After two stages of crushing, the steel slag enters the lifting conveyor from the discharge port of the second crusher 22. The lifting conveyor elevates the steel slag from a lower position to a certain height, providing suitable height conditions for subsequent screening operations. This mechanical lifting method is more reliable and consumes less energy than relying on slope sliding or pneumatic conveying, and there is no dust escape, making it very suitable for conveying high-temperature materials. The steel slag enters the screening machine from the discharge port of the lifting conveyor. The screening machine screens the steel slag, separating the qualified steel slag particles from the non-qualified steel slag particles according to the preset particle size requirements. This ensures that only qualified steel slag particles that meet the preset particle size requirements can be discharged from their discharge port and enter the subsequent high-temperature solid bulk material waste heat direct recovery device 3. This ensures the uniformity and stability of the material entering the core heat exchange device. The material with uniform particle size can form a material layer with stable porosity and consistent flow within the heat exchange device, thereby ensuring that the contact thermal resistance between the heat exchange tube and the steel slag is minimized and stable. This is an important prerequisite for achieving efficient and uniform heat exchange.

[0036] In one embodiment, the lifting conveyor includes a lifting bucket 231 and a lifting machine 232, the lifting machine 232 being used to control the vertical movement of the lifting bucket 231. By adjusting the operating speed of the lifting machine 232 and the loading capacity of the lifting bucket 231, the conveying volume of steel slag can be flexibly adjusted. When the production scale expands or shrinks, the conveying volume can be adjusted in a timely manner to meet the needs of different production stages, avoiding system inefficiency or resource waste caused by mismatched conveying volumes.

[0037] In one embodiment, the lifting conveyor further includes a feeding hopper 233, which is positioned above the lifting bucket 231 and has its inlet connected to the outlet of the second crusher 22. The outlet of the feeding hopper 233 is connected to the inlet of the lifting bucket 231. The feeding hopper 233 serves to buffer and guide the material, and its volume design can accommodate the discharge volume of the second crusher 22 within a certain period of time, preventing the material from directly impacting the lifting bucket 231 and ensuring the stability of the material conveying.

[0038] In one embodiment, the tail-end processing device 4 further includes a rod mill and a magnetic separator. The feed inlet of the rod mill is connected to the discharge outlet of the hot quenching tank 41 via a conveying device for crushing the steel slag after hot quenching. The magnetic separator is used to magnetically separate and recover metallic iron from the crushed steel slag.

[0039] After being processed in the hot slag 41, the steel slag enters the rod mill through its discharge port via a conveyor. The rod mill uses internal steel rods as grinding media to grind and crush the steel slag. During the rotation of the rod mill, the steel rods collide and rub against each other, breaking the steel slag into finer particles, allowing for better separation of metallic iron from other impurities and improving the efficiency of subsequent magnetic separation for recovering metallic iron.

[0040] Magnetic separators use magnetic force to adsorb metallic iron from steel slag, separating it from other non-magnetic impurities. The recovered metallic iron can be reused as a high-quality steelmaking raw material, while the remaining tailings can be used in the production of other building materials, transforming steel slag from hazardous solid waste into a high-value resource.

[0041] Compared with domestic steel enterprises' pretreatment processes for steel slag, such as water quenching, air quenching, hot pouring, hot simmering, and aging, this technology boasts advantages such as a short cooling cycle, high processing efficiency, high automation level, and high degree of cleanliness. It can maximize the recovery rate of metal materials and truly achieve mechanized, resource-based, safe, and clean steel slag treatment. The treated steel slag tailings meet national environmental protection policies and "zero emission" requirements, making it a key technology for steel enterprises to achieve "zero slag discharge." This significantly enhances my country's international competitiveness in the field of steel slag treatment, promotes the high-value utilization of steel slag, and enables steel slag resource utilization to leap from "usable" to "high-value." It has enormous economic and social benefits.

[0042] The above description of the disclosed embodiments enables those skilled in the art to implement or use this invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, this invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-temperature solid bulk material waste heat direct recovery system applied to high-temperature steel slag, characterized in that: include: A slag discharge tank is used to receive and temporarily store high-temperature molten steel slag discharged from a metallurgical furnace. A crushing and screening device, comprising a crusher and a conveying and screening mechanism, wherein the feed inlet of the crusher is connected to the discharge outlet of the discharge tank, and the feed inlet of the conveying and screening mechanism is connected to the discharge outlet of the crusher. A high-temperature solid bulk waste heat direct recovery device, wherein the inlet of the high-temperature solid bulk waste heat direct recovery device is connected to the outlet of the conveying and screening mechanism; The tail-end processing device includes a hot sealing tank, the inlet of which is connected to the outlet of the high-temperature solid bulk waste heat direct recovery device.

2. The high-temperature solid bulk material waste heat direct recovery system applied to high-temperature steel slag according to claim 1, characterized in that: The crusher includes a first crusher and a second crusher. The feed inlet of the first crusher is connected to the discharge outlet of the discharge tank, the feed inlet of the second crusher is connected to the discharge outlet of the first crusher, and the discharge outlet of the second crusher is connected to the feed inlet of the conveying and screening mechanism.

3. The high-temperature solid bulk material waste heat direct recovery system applied to high-temperature steel slag according to claim 2, characterized in that: The crushing and screening device also includes a buffer chamber, the inlet and outlet of which are connected to the outlet of the first crusher and the inlet of the second crusher, respectively.

4. The high-temperature solid bulk material waste heat direct recovery system applied to high-temperature steel slag according to claim 2, characterized in that: The conveying and screening mechanism includes a lifting conveyor and a screening machine. The feed inlet of the lifting conveyor is connected to the discharge outlet of the second crusher, the feed inlet of the screening machine is connected to the discharge outlet of the lifting conveyor, and the discharge outlet of the screening machine is connected to the feed inlet of the high-temperature solid bulk waste heat direct recovery device.

5. A high-temperature solid bulk material waste heat direct recovery system applied to high-temperature steel slag according to claim 4, characterized in that: The lifting conveyor includes lifting buckets and a lifting machine, the lifting machine being used to control the vertical movement of the lifting buckets.

6. A high-temperature solid bulk material waste heat direct recovery system applied to high-temperature steel slag according to claim 5, characterized in that: The lifting conveyor also includes a feeding hopper, which is located above the lifting bucket and has its inlet connected to the outlet of the second crusher, and its outlet connected to the inlet of the lifting bucket.

7. A high-temperature solid bulk material waste heat direct recovery system applied to high-temperature steel slag according to claim 1, characterized in that: The tail-end processing device also includes a rod mill and a magnetic separator. The feed inlet of the rod mill is connected to the discharge outlet of the hot quenching tank through a conveying device for crushing the steel slag after hot quenching. The magnetic separator is used to magnetically separate and recover metallic iron from the crushed steel slag.

Images