Treatment process for recycling energy from steel slag

Abstract

The invention discloses a treatment process and system for recycling energy from steel slag. The method comprises the steps that liquid steel slag is atomized through high-speed airflow and cooled to form high-temperature steel slag particles, and first high-temperature flue gas is generated; the steel slag particles are conveyed and continuously cooled, the particles are cooled to the preset temperature, and second high-temperature flue gas is discharged in the process; carrying out waste heat recovery on the first and second high-temperature flue gas; and at least part of the recovered flue gas is used as a cooling medium for recycling. According to the technical scheme, multiple strands of sensible heat generated in the granulation stage and the cooling stage can be recycled at the same time, a cyclic utilization path of a cooling medium is constructed, the use amount of fresh cooling gas is reduced, the energy utilization efficiency of the whole steel slag treatment process is improved, exhaust heat loss and system operation energy consumption are reduced, and energy saving and resource utilization in the steel slag treatment process are achieved.

Description

Technical Field

[0001] This invention relates to the field of steel slag treatment technology, and in particular to a treatment process and system for the resource recovery and energy recycling of steel slag. Background Technology

[0002] In steelmaking, slag-forming agents such as lime and fluorite are added to smelting equipment like converters and electric furnaces to facilitate the removal of impurities and adjust the composition of the metal. These agents react with sulfur, phosphorus, and other impurities in the molten iron at high temperatures to form slag. After smelting, this slag floating on top of the molten steel is poured off, forming liquid steel slag, typically at temperatures above 1400 degrees Celsius. Liquid steel slag not only contains high levels of silicates, aluminates, and calcium oxide, but also has a high specific heat capacity and high temperature; its sensible heat per unit mass is far greater than that of ordinary solid waste. Without proper treatment and energy recovery from liquid steel slag, not only will a large amount of heat energy be wasted, but long-term slag storage will also occupy land and have adverse environmental impacts. Therefore, how to recover the sensible heat while treating steel slag has become an important technical direction for steel enterprises to save energy, reduce carbon emissions, and improve the comprehensive utilization rate of resources.

[0003] Current production processes commonly employ hot quenching, natural cooling, and wet slag flushing to treat steel slag. A typical approach involves pouring liquefied steel slag into a slag pit or slag pot and subjecting it to prolonged hot quenching or water cooling in a high-temperature environment. Once the slag has cooled and solidified, it undergoes secondary processing such as crushing, grinding, and magnetic separation to recover scrap iron and obtain tailings. These processes are lengthy and require large land areas. During the cooling and handling of the liquefied steel slag, a large amount of high-temperature flue gas is directly released into the environment. The sensible heat of the steel slag itself is also dissipated disorderly through radiation and convection, with almost no effective utilization. Furthermore, the water or air used for cooling is often single-use and discharged immediately after use, increasing the consumption and processing burden of cooling media and carrying away a significant amount of usable heat during the emission of high-temperature flue gas. To improve energy utilization, existing technologies have proposed sending high-temperature liquid steel slag or granulated steel slag into grate coolers or waste heat boilers for cooling and waste heat recovery. However, these technologies often only utilize the high-temperature flue gas generated in a certain stage, lacking unified management and coordinated design for multiple flue gas streams in the granulation stage and subsequent cooling stage.

[0004] In summary, existing steel slag treatment technologies suffer from several drawbacks. Firstly, the high-temperature flue gas generated during the granulation and cooling processes of liquefied steel slag is not systematically collected and graded for recovery, resulting in insufficient utilization of sensible heat, high exhaust temperatures, and significant energy waste. Secondly, the gas used as the cooling medium is typically used in a single-pass flow pattern, lacking an effective recycling path, leading to large consumption of fresh cooling medium and high system operating energy consumption. Therefore, balancing efficient sensible heat recovery with the recycling of the cooling medium to improve the overall energy utilization efficiency and reduce operating energy consumption in the treatment of liquefied steel slag has become a critical technical challenge that urgently needs to be addressed. Summary of the Invention

[0005] This application provides a processing technology for the resource recovery of energy from steel slag. The main purpose of this invention is to solve the technical problems of existing wet treatment of steel slag, lack of recovery and utilization of waste heat and sensible heat, difficulty in recycling cooling medium, and high system energy consumption.

[0006] To achieve the above objectives, embodiments of this application provide a processing technology for energy recovery from steel slag, comprising: Liquid steel slag is atomized and cooled by a high-speed airflow to form high-temperature steel slag particles, and the first high-temperature flue gas is generated. The steel slag particles are conveyed and cooled by a cooling medium to reduce their temperature to a preset temperature, and a second high-temperature flue gas is discharged during the cooling process. The heat from the first high-temperature flue gas and / or the second high-temperature flue gas is recovered and utilized. The recycled first high-temperature flue gas and / or the second high-temperature flue gas are at least partially reused as the cooling medium.

[0007] To achieve the above objectives, this application also proposes a processing system for energy recovery from steel slag, comprising: The granulation device is used to atomize and cool liquid steel slag through a high-speed airflow to form high-temperature steel slag particles and generate the first high-temperature flue gas. A grate cooler is used to transport the steel slag particles and cool them through a cooling medium to reduce the temperature of the steel slag particles to a preset temperature, and to discharge a second high-temperature flue gas during the cooling process. Waste heat recovery device, used to recover and utilize the heat of the first high-temperature flue gas and / or the second high-temperature flue gas; A circulation device is used to recycle at least a portion of the recovered first high-temperature flue gas and / or the second high-temperature flue gas as the cooling medium.

[0008] In the processing technology of this invention, after the liquid steel slag is poured out from metallurgical equipment such as a rotary kiln, it directly enters the high-speed airflow zone. The high-speed airflow impacts the continuous flow of steel slag, breaking it into a large number of small droplets. A sensible heat transfer is completed during the full contact between the steel slag droplets and the airflow. Part of the high-temperature energy of the liquid steel slag is rapidly transferred to the gas, causing the gas to heat up and form the first high-temperature flue gas. The other part remains in the partially cooled but still high-temperature steel slag particles. Compared to naturally cooling the entire tank of steel slag, this granulation method significantly increases the contact area between the steel slag and the gas. The heat exchange path between the gas and solid is compressed within the granulation space, and the high-temperature energy is more concentratedly transferred to the easily transportable gaseous carrier. Simultaneously, high-temperature steel slag particles with relatively controllable particle size and temperature are obtained, creating conditions for subsequent continuous cooling and energy recovery.

[0009] After obtaining high-temperature steel slag particles, the particles are fed into a conveying unit equipped with a cooling medium for further cooling. The cooling medium continuously contacts the particles along the conveying path, causing the residual sensible heat inside the particles to gradually release into the gas, thus forming a second high-temperature flue gas. Through this process, the heat that has not yet been completely transferred from the high-temperature solid is fully extracted, and the sensible heat of the liquid steel slag, which was originally dispersed in various stages, is orderly concentrated into the first and second high-temperature flue gases, facilitating their unified delivery to the waste heat recovery device for heat recovery. Due to the high temperature and high calorific value of the two flue gases, the waste heat recovery device can operate stably under high operating conditions, generating steam or other usable heat transfer media. After heat recovery, the flue gas temperature is significantly reduced, but it still retains a certain cooling capacity. At least a portion of it is returned as a cooling medium for recycling, forming a closed loop in the cooling system. This reduces the amount of fresh cooling gas required for replenishment, lowers the consumption of auxiliary energy such as fan drives, and, by repeatedly utilizing the temperature distribution within the same gas stream, completes the cooling process of the steel slag at a lower emission temperature, reducing the residual heat loss carried by the emitted flue gas. Through the synergistic design of continuous granulation, staged transfer of sensible heat, and flue gas recycling, the sensible heat of steel slag is systematically and hierarchically recovered and reused multiple times during the entire process of steel slag transforming from liquid to solid particles. This solves the problems of insufficient sensible heat recovery and difficulty in recycling cooling media during steel slag treatment, improves overall energy utilization efficiency, and reduces system operating energy consumption. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of one embodiment of the energy recovery process for steel slag resource utilization in this invention. Figure 2 This is a schematic diagram of one embodiment of the energy recovery system for steel slag resource utilization in this invention. Figure 3 This is a partial structural schematic diagram of a processing system for energy recovery from steel slag in an embodiment of the present invention.

[0012] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0014] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0015] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the term "and / or" throughout the text includes three solutions; taking A and / or B as an example, it includes technical solution A, technical solution B, and a technical solution that simultaneously satisfies A and B. Furthermore, the technical solutions of various embodiments can be combined with each other, provided that they are feasible for those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0016] One embodiment of this application provides a processing technology for energy recovery from steel slag. Figure 1 This is a flow chart illustrating a process for energy recovery from steel slag, provided as an embodiment of this application. In this embodiment, the method includes: Please see Figure 1 Liquid steel slag is atomized and cooled by a high-speed airflow to form high-temperature steel slag particles, and the first high-temperature flue gas is generated. In one embodiment of the present invention, the high-speed airflow contains water vapor to promote the decomposition of free calcium oxide and free magnesium oxide in the liquid steel slag.

[0017] It should be noted that water vapor refers to water in the gaseous phase, including saturated water vapor or mixed gases containing a certain volume fraction of water vapor. Free calcium oxide and free magnesium oxide in liquid steel slag refer to CaO and MgO that have not yet formed stable silicate or aluminate mineral phases with oxides such as silicon and aluminum. These components undergo hydration upon contact with water, accompanied by volume expansion. If hydration only begins in the finished steel slag stage, it can easily lead to later expansion and pulverization.

[0018] Specifically, a branch line connected to the plant's steam network can be installed on the air supply duct that provides high-speed airflow. By adjusting the steam valve, the high-speed airflow entering the granulation unit can be mixed with steam before reaching the nozzle, forming a high-speed airflow containing water vapor. Alternatively, atomizing nozzles can be arranged in the air supply duct to spray an appropriate amount of industrial water into the ambient air. The water droplets will instantly vaporize in the high-temperature area to form water vapor, so that the high-speed airflow reaches the set absolute humidity before contacting the liquid steel slag. For example, under the condition that the temperature of converter steel slag is about 1400 degrees Celsius, saturated water vapor is mixed with compressed air. The water vapor content in the mixed gas is controlled to provide the water required for the hydration of free calcium oxide and free magnesium oxide without causing excessive rapid cooling or unstable granulation due to excessive water content. After the liquid steel slag is atomized into fine droplets by the high-speed airflow containing water vapor, the water vapor diffuses on the surface and inside of the droplets, hydrating with the free calcium oxide and free magnesium oxide to generate calcium hydroxide, magnesium hydroxide, and subsequent more stable hydration products. This allows the volume change to be released in advance during the granulation and cooling stages, thereby reducing the risk of delayed expansion during subsequent storage and application, and improving the volume stability of the steel slag particles. In other embodiments, the high-speed airflow containing water vapor can also be composed of high-humidity hot air or flue gas containing water vapor. As long as the gas is adjusted to a predetermined moisture content before reaching the granulation area, the purpose of promoting the dissolution of free calcium oxide and free magnesium oxide can be achieved, while maintaining the stability and controllability of the granulation and cooling process of the liquid steel slag.

[0019] In one embodiment of the present invention, the step of atomizing and cooling liquid steel slag through a high-speed airflow to form high-temperature steel slag particles includes: Liquid steel slag is atomized by a high-speed airflow, and the resulting steel slag droplets enter the granulation chamber with a parabolic trajectory. The droplets are cooled and solidified in the granulation chamber to form high-temperature steel slag particles, which are then discharged from the outlet of the granulation chamber. The first high-temperature flue gas is collected through the flue gas outlet of the granulation chamber.

[0020] It should be noted that the granulation chamber is a closed or semi-closed space arranged to the side of the slag dumping area. Its interior is lined with a refractory lining and has an upper slag droplet inlet, a lower particle outlet, and a side or upper flue gas outlet. After flowing out of the trough, the liquid slag encounters a high-speed airflow at the granulation device. The high-speed airflow impacts the slag flow along a predetermined direction, atomizing the continuous slag flow into a large number of slag droplets. Because the high-speed airflow not only changes the falling direction of the slag droplets but also imparts a certain horizontal velocity component, the droplets, under the combined action of gravity and inertia, fly into the granulation chamber's internal space in a parabolic trajectory. By rationally setting the relative height and spacing between the granulation device and the granulation chamber inlet, the slag droplets can be dispersed and cover a predetermined area upon entering the granulation chamber. This avoids the droplets colliding with the furnace wall and forming a crust, while ensuring that the droplets have sufficient flight distance and time in the gas phase to complete preliminary cooling. In another embodiment, the granulation device can employ a multi-nozzle arrangement, so that steel slag droplets from different nozzles overlap and distribute in the inlet area of ​​the granulation chamber, which can also form a group of steel slag droplets that enter the granulation chamber with a parabolic trajectory and obtain similar spatial distribution and cooling conditions.

[0021] After steel slag droplets enter the granulation chamber, they remain in continuous contact with the cooling gas and undergo radiative heat exchange with the inner wall of the granulation chamber. The droplets gradually cool from the outside in until they solidify into high-temperature steel slag particles. To ensure a stable and controllable cooling process, the flow rate and temperature of the cooling medium entering the granulation chamber, as well as the particle size range of the steel slag droplets, can be adjusted. This ensures that the residence time of the steel slag droplets in the granulation chamber is sufficient to complete the transformation from liquid to solid state, while maintaining the overall temperature of the particles within a predetermined high-temperature range. This allows the particles to possess sufficient mechanical strength and shape stability while retaining an appropriate amount of sensible heat for subsequent processes. For example, when the converter slag temperature is 1400 degrees Celsius, the effective height of the granulation chamber can be designed to be on the order of several meters. With a suitable amount of cold air, the steel slag droplets can solidify during their flight and descent within the granulation chamber, resulting in high-temperature steel slag particles with concentrated particle size, high temperature, and no sticking. By completing the cooling and solidification process within the granulation chamber, the uneven internal cooling caused by the accumulation of large slag masses can be avoided, reducing the difficulty of subsequent crushing and ensuring that the high-temperature particles enter the subsequent cooling and conveying units in a regular pattern. In other embodiments, a suitable amount of preheated air or a mixture containing water vapor can be introduced into the granulation chamber to adjust the cooling intensity and promote the dissolution of unstable components within the steel slag. As long as the process of solidifying the steel slag from droplets into high-temperature steel slag particles in the granulation chamber is achieved, it constitutes an equivalent implementation of this step.

[0022] The outlet of the granulation chamber is located at the bottom or lower side of the chamber to orderly discharge the cooled and solidified high-temperature steel slag particles. The outlet can connect to the downstream grate cooler inlet or intermediate buffer hopper. A heat-resistant chute, star-shaped discharge valve, or vibrating feeder can be installed at the outlet to control the discharge rate and prevent backflow of high-temperature flue gas from the outlet direction. In converter steel slag processing scenarios, after the high-temperature steel slag particles solidify in the granulation chamber, they fall under their own weight to the outlet area and are uniformly fed into the grate cooler grate bed by a vibrating feeder. This ensures continuous and uniform feeding to the grate cooler and prevents particle agglomeration at the outlet. By concentrating the solidified particles and discharging them from the granulation chamber outlet, spatial separation of solid materials and upper high-temperature flue gas can be achieved. Solid particles are transported along the downstream material channel, while the gas is collected through an independent flue gas outlet, creating conditions for subsequent material cooling and waste heat recovery. In another embodiment, a mechanical airlock device, such as a rotary feeder, can also be installed at the outlet of the granulation chamber to further reduce flue gas leakage and improve flue gas collection efficiency while ensuring smooth discharge of granules.

[0023] The flue gas outlet of the granulation chamber is located on the top or side wall of the upper part of the granulation chamber and is connected to the waste heat recovery device through a heat-resistant flue. It is used to centrally collect the first high-temperature flue gas generated by the cooling of liquid steel slag. As the steel slag droplets continuously transfer heat to the surrounding gas during their flight and cooling process within the granulation chamber, the large amount of high-temperature gas accumulated in the upper region of the granulation chamber constitutes the first high-temperature flue gas. By connecting an induced draft fan to the flue gas outlet or utilizing the suction effect of a downstream waste heat boiler, the high-temperature flue gas within the granulation chamber can be stably discharged. In practical applications, a simple baffle or inertial separation structure can be installed before the flue gas outlet to reduce the probability of entrained particles entering the flue and reduce wear on the waste heat recovery equipment. Since the first high-temperature flue gas has a high temperature when it forms in the granulation chamber and contains the portion with the highest sensible heat potential of the steel slag, centrally collecting this portion of the flue gas through an independent flue gas outlet and sending it to the waste heat recovery device is beneficial for efficient heat exchange at a higher inlet temperature, improving the overall system's heat recovery level. In other embodiments, the granulation chamber can be provided with multiple flue gas outlets, each corresponding to a different height or a different area, and connected to the waste heat recovery device in parallel or series by a collecting flue. As long as the first high-temperature flue gas generated during the granulation of steel slag is effectively collected, it constitutes an equivalent implementation of this step.

[0024] In one embodiment of the present invention, the temperature of the steel slag particles discharged from the outlet of the granulation chamber is 350°C to 850°C.

[0025] Specifically, the temperature of the steel slag particles discharged from the granulation chamber at 350℃~850℃ refers to the actual temperature of the steel slag particles after they have completed their transformation from droplets to solid particles within the granulation chamber, and before they fall into the outlet area and have fully exchanged heat with the external environment. This temperature can be monitored in real time by arranging a high-temperature resistant infrared thermometer or a sheathed thermocouple near the outlet of the granulation chamber. The measuring point can be set inside the material discharge channel through which the particles flow to ensure that the measured data reflects the temperature state of the particles immediately after they are discharged from the granulation chamber. This temperature range is achieved by adjusting the jet pressure of the high-speed airflow, the nozzle flow rate, the temperature and flow rate of the cooling medium within the granulation chamber, and the particle size of the steel slag droplets. On the one hand, the steel slag droplets need sufficient flight and heat exchange time within the granulation chamber to complete the outer shell solidification and form transportable solid particles. On the other hand, to avoid excessive cooling within the granulation chamber leading to premature loss of sensible heat, the temperature and heat exchange capacity of the cooling medium need to be maintained at a level that keeps the particle outlet temperature above 350℃. Simultaneously, by controlling the average size of the slag droplets and the gas distribution within the granulation chamber, the particles are kept free of a significant semi-molten phase, and their overall temperature does not exceed 850°C. This ensures that the particles do not adhere, deform, or suffer structural damage before falling into the downstream grate cooler. This temperature range keeps the slag in a stable, solid state at the outlet, retaining medium-to-high temperature heat, allowing for direct subsequent transport and further cooling, thus facilitating a high sensible heat recovery rate. In other embodiments, this temperature range can also be achieved by changing the effective height of the granulation chamber, adjusting the air inlet direction, or using a multi-nozzle arrangement. As long as the slag particles remain stably within the 350°C~850°C range at the outlet, the functional requirements of this step are met.

[0026] Preferably, the temperature of the steel slag particles discharged from the outlet of the granulation chamber is 500℃~600℃.

[0027] Please continue reading. Figure 1 The steel slag particles are conveyed and cooled by a cooling medium to reduce their temperature to a preset temperature, and a second high-temperature flue gas is discharged during the cooling process. In one embodiment of the present invention, cooling the steel slag particles with a cooling medium includes: Multiple cooling zones are sequentially arranged along the conveying direction of the steel slag particles. Cooling media are sequentially supplied to the steel slag particles through each cooling zone, so that the temperature of the steel slag particles decreases step by step.

[0028] Specifically, multiple cooling zones refer to several independent cooling units arranged sequentially along the conveying direction of the steel slag particles. Each cooling unit is equipped with a cooling medium inlet, allowing the cooling medium to act on the steel slag particles in a segmented manner at different locations. For example, in scenarios where a grate cooler is used as the conveying device, multiple partitioned air chambers can be set below the grate cooler, each corresponding to a cooling zone and connected to independent air supply pipelines and regulating valve groups, allowing the flow rate, pressure, and temperature of the cooling medium in each cooling zone to be individually controlled. When the high-temperature steel slag particles fall from the outlet of the granulation chamber onto the grate bed of the grate cooler, they pass through multiple cooling zones sequentially with the reciprocating motion of the grate bed. The cooling medium in each cooling zone passes through the particle layer from bottom to top, engaging in convective heat exchange, causing the temperature of the steel slag particles to gradually decrease in each cooling zone, reaching a preset lower temperature in the final cooling zone. By supplying the cooling medium in stages, the cooling process can be precisely controlled from strong to weak or from weak to strong, preventing structural cracking of the steel slag particles due to rapid cooling at the high-temperature end, while ensuring sufficient sensible heat recovery at the low-temperature end, achieving a gradual and stable temperature decrease. In the converter steel slag processing, by setting different air volumes and temperatures for multiple cooling zones, a continuous but controllable cooling gradient can be formed along the conveying path of the steel slag particles, thereby improving cooling efficiency and waste heat recovery. In other embodiments, the multiple cooling zones can also be composed of multiple fluidized bed cooling devices or rotary cooling cylinders connected in series. As long as the cooling medium is supplied sequentially to the particles along the conveying direction of the steel slag particles, and the particle temperature decreases gradually, this constitutes an equivalent implementation of this step.

[0029] In one embodiment of the invention, the steel slag particles are transported via a grate cooler.

[0030] It should be noted that the transport of steel slag particles via a grate cooler refers to the process where high-temperature steel slag particles discharged from the granulation chamber outlet fall onto the grate bed of the grate cooler, and are continuously moved along a set conveying direction by the reciprocating propulsion structure of the grate cooler. The grate cooler includes an upper shell, a lower shell, a grate bed, a grate bed drive device, and multiple air chambers located within the lower shell. Each air chamber supplies cooling medium upwards to the grate bed. When the grate bed's propulsion mechanism performs reciprocating linear motion or stepped propulsion motion at a predetermined frequency, the steel slag particles on the grate bed are pushed forward segment by segment under the combined action of friction and gravity, achieving continuous transport. Simultaneously, the cooling medium from the air chambers enters the particle layer through the grate bed pores, undergoing forced convection heat exchange with the steel slag particles, ensuring uniform cooling of the particles during transport. For example, in the case of converter slag processing, slag particles fall onto the high-temperature end of the grate and move towards the low-temperature end at a speed of several centimeters to tens of centimeters per second via the grate propulsion structure. During this process, they pass through multiple cooling zones in sequence, causing the particle temperature to gradually decrease over the long transport path, eventually leaving the grate cooler at near-room temperature or a predetermined temperature. The grate cooler integrates the conveying and cooling processes, which traditionally require multiple devices, into one unit by simultaneously handling material transport and cooling heat exchange, thus improving sensible heat recovery efficiency and reducing the number of devices. In other embodiments, slag particles can also be transported using grate coolers with different structural forms, such as moving grate structures or multi-stage variable-speed propulsion structures. As long as the slag particles move forward on the grate with the propulsion mechanism and receive cooling media during this process, it can be considered an equivalent implementation of this step.

[0031] In one embodiment of the present invention, the second high-temperature flue gas includes multiple streams of flue gas generated by each of the cooling zones, and each stream of flue gas is collected and recycled.

[0032] Specifically, the second high-temperature flue gas refers to the high-temperature gas discharged from each cooling zone after the steel slag particles have exchanged heat with the cooling medium in multiple cooling zones. The gases generated by the multiple cooling zones together constitute the second high-temperature flue gas. Along the conveying direction of the steel slag particles, an independent flue gas outlet is set on the shell of each cooling zone, and the gases generated in each cooling zone are led out separately through heat-resistant flues. For example, when a grate cooler is used as the cooling and conveying device, a corresponding flue gas collecting hood and flue gas branch pipe can be configured for each air chamber. This allows the cooling medium passing through the steel slag particle layer in that cooling zone to absorb sensible heat and then be led out through the branch pipe, forming a high-temperature flue gas with relatively stable temperature and flow rate. Each branch pipe is connected to a waste heat recovery device through a regulating valve. Based on the differences in flue gas temperature and dust concentration in each cooling zone, the high-temperature flue gas can be directly sent to the radiation section, while the medium- and low-temperature flue gas can be sent to the convection section or the economizer inlet, thereby achieving staged heat exchange and orderly recovery. Because each flue gas stream is collected separately, premature mixing that would lower the overall temperature is avoided. This allows the high-temperature flue gas to participate in heat exchange at a higher inlet temperature, improving waste heat recovery efficiency. It also facilitates the individual adjustment of flow rate and oxygen content in different areas to meet the operational requirements of the boiler or other waste heat recovery equipment. In other embodiments, multiple cooling zones can be arranged in a series of fluidized beds or multi-stage rotary cooling cylinders. An equivalent implementation of this step is achieved simply by providing independent flue gas outlets in each cooling zone and separately leading out and connecting each flue gas stream to the waste heat recovery device.

[0033] In one embodiment of the invention, in the conveying direction of the steel slag particles, the temperature of the cooling medium in the cooling zone at the end is lower than that in any of the other cooling zones.

[0034] It should be noted that, in the direction of steel slag particle conveying, the cooling medium temperature in the final cooling zone is lower than that in any other cooling zone. This is achieved by classifying and configuring the cooling medium source and supply method for each cooling zone. When multiple cooling zones are set up along the conveying direction of steel slag particles, each cooling zone can be equipped with an independent cooling medium supply branch, and regulating valves and temperature detection elements can be arranged on the branch. The final cooling zone directly introduces ambient air or simply pre-treated low-temperature air through an independent air inlet branch, so that the cooling medium temperature in this cooling zone is close to the ambient temperature or at a predetermined low level. Other cooling zones before the final zone preferentially use high-temperature or medium-temperature gas returned from the waste heat recovery device or upstream flue as the cooling medium. If necessary, a portion of cold air can be mixed in according to the gas temperature to adjust to the target temperature range. By comparing the temperature detection signals at the cooling medium inlet of each cooling zone, the regulating valves of each branch are linked for control, so that the cooling medium temperature in the final cooling zone is always maintained as the lowest among all cooling zones. Taking converter slag treatment as an example, after high-temperature slag particles enter the grate cooler from the high-temperature end, they first contact the relatively high-temperature circulating gas, releasing high-level sensible heat for waste heat recovery. As the particles gradually approach the outlet along the conveying direction, they then contact the cooling medium in the lowest-temperature end cooling zone, causing the particles to finally cool to a low-temperature state suitable for conveying and storage. This arrangement ensures sufficient cooling capacity in the end cooling zone, making the temperature of the slag particles exiting the machine stable and controllable; it also prioritizes the use of high-temperature media for heat exchange in the high-temperature section, improving the energy quality utilization of the system. In other embodiments, the lowest-temperature cooling medium can be introduced from the end of the material conveying process and pass through each cooling zone in the opposite direction to form countercurrent cooling. As long as the temperature of the cooling medium in the end cooling zone is lower than that in any other cooling zone along the slag particle conveying direction, this is an equivalent implementation of this step.

[0035] Please continue reading. Figure 1 The heat of the first high-temperature flue gas and / or the second high-temperature flue gas is recovered and utilized. Specifically, recovering and utilizing the heat from the first and / or second high-temperature flue gas refers to introducing the first high-temperature flue gas obtained from the granulation chamber flue gas outlet and the second high-temperature flue gas obtained from the flue gas outlets of each cooling zone into a waste heat recovery device through a closed flue. This allows the flue gas to exchange heat with the working fluid, transferring the sensible heat carried in the flue gas into usable thermal energy. In the converter slag treatment scenario, a waste heat boiler is preferred as the waste heat recovery device. The flue gas is sequentially introduced into the radiant heating surface and the convective heating surface, with feedwater flowing inside the heating surface. As the first and second high-temperature flue gas flow along the flue, their heat is transferred to the water or saturated water through the pipe wall, generating steam at a certain pressure and temperature, which is then sent to the plant's steam network for production heating or power generation. In this way, the sensible heat released by the liquid steel slag during granulation and cooling is converted into a stable steam heat source, reducing boiler fuel consumption. At the same time, the flue gas temperature is reduced to a predetermined emission or reuse level, reducing the burden on subsequent cooling and purification. In other embodiments, the waste heat recovery device may also employ a hot air heat exchanger, a hot water heat exchanger, or a thermal oil heat exchanger to use the heat from the first high-temperature flue gas and / or the second high-temperature flue gas to heat process air, process water, or thermal oil. As long as the sensible heat of the flue gas is transferred to the usable medium through the heat exchange equipment, it constitutes an equivalent implementation of this step.

[0036] Please continue reading. Figure 1 The first high-temperature flue gas and / or the second high-temperature flue gas, after being recycled, will be at least partially reused as the cooling medium.

[0037] Specifically, recycling at least a portion of the recovered first and / or second high-temperature flue gas as a cooling medium means that after waste heat recovery, the flue gas, whose temperature and cleanliness meet the requirements, is reintroduced into the granulation unit and / or multiple cooling zones via pipelines and fans as a source of high-speed airflow or cooling medium. Specifically, the first and second high-temperature flue gas can be jointly introduced into the waste heat recovery unit. After releasing heat to the working fluid in the heat exchange tube bundle, the flue gas temperature is reduced to a predetermined range, such as around 200 degrees Celsius. The flue gas then undergoes dust removal treatment by a dust collector to remove most solid particles, and is then sent into the main circulation pipe by an induced draft fan. Branches are set on the main circulation pipe; a portion of the flue gas enters the air supply duct before the granulation unit after passing through a regulating valve, serving as a source of high-speed airflow; the other portion of the flue gas is sent into the corresponding air chamber through the inlet branches of each cooling zone, serving as the cooling medium for that cooling zone. Temperature detection elements and proportional control valves are installed on each branch. By adjusting the mixing ratio of flue gas and fresh air, the recycled flue gas reaches the target temperature and oxygen content before entering the granulation device or cooling zone. This ensures sufficient heat exchange capacity for liquid steel slag and steel slag particles while avoiding excessively high temperatures that could affect equipment lifespan or excessively low temperatures that could reduce the value of waste heat utilization. Since the recycled flue gas has already completed high-level heat output in the waste heat recovery device, its remaining heat is at a temperature level suitable for use as a cooling medium. Recycling it significantly reduces the amount of fresh air or other cooling media needed, lowers fan drive energy consumption, and allows for multiple uses of the same gas within a closed pipeline, reducing the total amount and temperature of directly emitted high-temperature flue gas. In other embodiments, it is also possible to select only one of the recycled first or second high-temperature flue gas to be connected to the cooling medium circulation loop, or to first mix the recycled flue gas with a certain proportion of inert gas or nitrogen to adapt to special operating conditions. As long as a portion of the flue gas is returned after heat recovery for use as a cooling medium in the granulation or cooling process, this is an equivalent implementation of this step.

[0038] The above describes the processing technology for energy recovery from steel slag in embodiments of the present invention. The following describes the processing system for energy recovery from steel slag in embodiments of the present invention. Please refer to [link to relevant documentation]. Figure 2 and Figure 3 One embodiment of the energy recovery system for steel slag resource utilization according to the present invention includes: Granulation device 101 is used to atomize and cool liquid steel slag through high-speed airflow to form high-temperature steel slag particles and generate first high-temperature flue gas; The grate cooler 102 is used to transport the steel slag particles and cool them through a cooling medium to reduce the temperature of the steel slag particles to a preset temperature, and discharges a second high-temperature flue gas during the cooling process. Waste heat recovery device 103 is used to recover and utilize the heat of the first high-temperature flue gas and / or the second high-temperature flue gas; The circulation device 104 (not shown) is used to circulate at least a portion of the recovered first high-temperature flue gas and / or second high-temperature flue gas as the cooling medium.

[0039] The granulation device 101 is used to atomize liquid steel slag into steel slag droplets through a high-speed airflow, and to perform preliminary cooling during the droplet flight. The granulation device 101 may include structures such as a chute, a granulation nozzle, and a granulation chamber inlet.

[0040] In a typical implementation, the chute, constructed of heat-resistant steel or a composite refractory lining, guides the liquefied steel slag to the granulation nozzle area. The granulation nozzles can be Venturi or Laval nozzles, connected to a compressed air blower or high-pressure blower to obtain a high-speed airflow. This high-speed airflow is injected at a predetermined angle into the liquefied steel slag flow, causing the slag to be dispersed into droplets with a diameter of approximately one to five millimeters under the action of shear force, impact force, and aerodynamic forces. The slag droplets ejected from the nozzles enter the granulation chamber along a parabolic trajectory due to inertia and gravity. The granulation chamber inlet is typically equipped with a refractory material protective structure and has an enclosed space for collecting the initial high-temperature flue gas generated during the granulation process.

[0041] In this structure, the granulation device 101 transforms the liquid steel slag from a continuous state to a droplet state, enabling more efficient transfer of the sensible heat of the steel slag to the high-speed airflow, forming the first high-temperature flue gas, and simultaneously forming high-temperature steel slag particles with uniform and controllable temperature. In other embodiments, the granulation nozzle can be replaced with a ring-shaped spray structure, a multi-nozzle array structure, or a double-sided counter-current spray structure, as long as sufficient contact between the high-speed airflow and the liquid steel slag is achieved to form droplets, constituting an equivalent scheme of the device.

[0042] The waste heat recovery device 103 functions to exchange heat between the first high-temperature flue gas and / or the second high-temperature flue gas, so that the sensible heat in the flue gas is recovered as usable thermal energy. The waste heat recovery device 103 may include a waste heat boiler body, heat exchange tube bundle, induced draft device, and feedwater / steam system.

[0043] In a typical implementation, the waste heat boiler adopts a horizontal, straight-through structure, consisting of a radiant heating surface, a convective heating surface, and an economizer. First and second high-temperature flue gas enter the radiant zone through the flue, transferring their sensible heat to the water in the evaporator tube bundle, causing the water to absorb heat and vaporize. The flue gas then enters the convective zone for further heat exchange with the superheater or evaporator, and finally enters the economizer to heat the feedwater. An induced draft fan maintains the flow of flue gas, ensuring effective heat transfer. The steam output from this device can serve as a heat source for the plant's steam system.

[0044] In scenarios requiring lower-grade heat energy, the waste heat recovery device 103 can also employ an air preheater, a hot air heat exchanger, a hot water heat exchanger, or a thermal oil heater. As long as the sensible heat of the flue gas can be transferred to the usable medium, it is an equivalent implementation method of this solution.

[0045] With the above structure, the waste heat recovery device 103 can effectively reduce the flue gas emission temperature, provide a suitable temperature range for recycling, and reduce overall energy consumption.

[0046] The circulation device 104 is used to recycle the treated flue gas output from the waste heat recovery device 103 back into the granulation device 101 or the grate cooler 102 as a cooling medium, thereby realizing the recycling of cooling gas. The circulation device 104 may consist of components such as circulation pipelines, dust collectors, temperature control devices, and circulation fans.

[0047] In a typical implementation, the flue gas from the outlet of the waste heat recovery device 103 is treated by a dust collector and then enters the main circulation pipe. The main circulation pipe is connected to the air inlet channels of the granulation device 101 and multiple cooling zones via branch pipes. A circulating fan maintains the gas flow within the pipes, and regulating valves are used to control the gas distribution and temperature of different branches. If necessary, fresh air can be introduced into the branch pipes to adjust the temperature of the circulating gas to meet the cooling requirements of different workstations. For example, the granulation device 101 may require a higher temperature circulating gas to avoid over-cooling of the slag droplets, while the final cooling zone may require a lower temperature circulating gas to achieve final cooling.

[0048] This structure can significantly reduce the amount of fresh air used, lower fan energy consumption, and allow the same gas to be used multiple times within the system, thereby improving the overall sensible heat utilization rate.

[0049] In other embodiments, the circulation device 104 may also use a regenerating fan, a mixing box structure, or a heat pipe coupling structure. As long as the recycled flue gas can be sent back into the cooling medium path, it is an equivalent implementation.

[0050] It should be noted that the cooling medium refers to the type of gas used to exchange heat with high-temperature steel slag particles, thereby lowering the particle temperature. The cooling medium can be implemented in the following ways: 1. Fresh air: The ambient air is filtered and then delivered to each cooling zone. The structure is simple and the source is stable.

[0051] 2. The first and / or second high-temperature flue gas after recycling: After being cooled and dusted by the waste heat recovery device 103, they can be reused as a cooling medium.

[0052] 3. Mixed gas of air and recovered flue gas: By adjusting the mixing ratio, the gas temperature is made to meet the needs of different cooling zones, ensuring a continuous and stable cooling gradient.

[0053] 4. Mixed gas containing water vapor: Suitable for promoting the dissolution of free calcium oxide and free magnesium oxide inside steel slag, but the water vapor content needs to be controlled according to the working conditions to avoid excessive humidity affecting particle flowability.

[0054] 5. Mixed gas of inert gas (such as nitrogen) and recycled flue gas: suitable for preventing oxidation or meeting special process environment requirements.

[0055] Any cooling medium that can effectively exchange heat with steel slag particles and achieve a temperature drop falls within the scope of the cooling medium of this invention.

[0056] In addition to the embodiments described above, in some embodiments, after the liquid steel slag is atomized and cooled by a high-speed airflow to form high-temperature steel slag particles, the method further includes: setting up a secondary injection area in the granulation chamber along the path of the steel slag particles falling from the first parabolic trajectory to the grate cooler; when the steel slag particles enter the secondary injection area, jet gas is injected from the secondary nozzles set in the secondary injection area and arranged upwards, so that the steel slag particles obtain an upward velocity component in the granulation chamber and fly in the second parabolic trajectory in the granulation chamber before falling into the grate cooler, thereby extending the flight path and residence time of the steel slag particles in the high-temperature atmosphere.

[0057] It should be noted that the first parabolic path refers to the flight trajectory of slag droplets formed after liquid steel slag is atomized by a high-speed airflow, from near the granulation device to when they naturally fall towards the inlet plane of the grate cooler, under the combined action of gravity and the initial velocity given by the high-speed airflow. The downstream space of the first parabolic path refers to the latter part of the trajectory from the starting point to the landing point, corresponding to the spatial position traversed by the steel slag particles after completing most of their descent, approaching the lower part of the granulation chamber, and about to fall into the grate cooler. This space can be defined by geometric boundaries within the granulation chamber, for example, with the inner wall as the side boundary, a horizontal section above a certain height of the grate cooler inlet as the lower boundary, and a corresponding section at a predetermined position on the first parabolic path as the upper boundary, so that the particles in this space are in the middle and later stages of the first parabolic descent. In actual arrangement, the secondary nozzle can be installed in the granulation chamber near the grate cooler, within a height range below the highest point of the first parabola and above the grate cooler inlet. This ensures that particles falling along the first parabola path will inevitably pass through the secondary injection area when passing through this height range, thereby gaining an upward velocity component under the action of the injected gas and being lifted onto the second parabola trajectory.

[0058] By defining the above limitations, it can be ensured that the secondary injection occurs after the steel slag particles have essentially completed their transformation from liquid to solid, achieved stable shape, and cooled to the predetermined high-temperature range, rather than during the initial droplet formation or near-complete cooling stage. This means that within the first parabolic segment, the steel slag particles primarily complete high-speed forming and the transfer of high-level sensible heat to the first high-temperature flue gas; after entering the downstream space of the first parabolic path, although the particle temperature decreases somewhat, it remains in a medium-high temperature state, with a large amount of usable heat still remaining inside. At this point, by using a secondary nozzle to lift the particles in this space to the second parabolic trajectory, a controlled flight path can be added within the limited volume of the granulation chamber, allowing the particles to continue convective heat transfer and mass exchange with the injected gas in a suspended state. On the one hand, the extra flight time allows the residual sensible heat inside the particles to be transferred to the gas more fully, reducing the instantaneous heat load when entering the grate cooler. This helps to reduce the thermal shock at the beginning of the grate cooler and increase the proportion of overall residual heat carried away by the gas phase. On the other hand, the secondary injection zone and the second parabolic trajectory can be used in conjunction with injection gases of specific compositions, providing a space and time window for the subsequent introduction of reactive gases containing carbon dioxide and water vapor into this zone. This allows the particles to undergo an additional controllable reaction zone within a suitable temperature range, thus achieving both sensible heat recovery and particle stabilization without adding independent reaction equipment, forming a comprehensive effect that is difficult to achieve with a single parabolic flight.

[0059] Optionally, the secondary nozzle is connected to a cooling gas branch and a reactive gas branch. The reactive gas contains at least carbon dioxide and water vapor, wherein the carbon dioxide is at least partially derived from the flue gas discharged during the waste heat recovery process, and the water vapor is obtained by injecting water or water vapor into the reactive gas. An infrared thermometer is installed downstream of the first parabolic trajectory in the granulation chamber to detect the surface temperature of the steel slag particles before entering the secondary injection area. When the detected surface temperature is within a preset temperature range, the secondary nozzle is controlled to open and reactive gas containing carbon dioxide and water vapor is supplied to the second parabolic trajectory area. When the detected surface temperature is lower than the lower limit of the preset temperature range, the secondary nozzle is controlled to close and / or only cooling gas is supplied to the secondary nozzle.

[0060] Specifically, the cooling gas refers to the gas primarily used to remove the sensible heat from the steel slag particles and lower their temperature. Its composition can be air, first-temperature flue gas cooled by the waste heat recovery device, and / or second-temperature flue gas, or a mixture of the above gases. The reactive gas refers to the gas that, while participating in particle cooling, also reacts with free calcium oxide and free magnesium oxide in the steel slag particles in a gas-solid reaction. It contains at least carbon dioxide and water vapor. The carbon dioxide is preferably obtained by diverting it from the flue gas discharged from the waste heat recovery device to reduce the need for purchased carbon dioxide. The water vapor is obtained by injecting an appropriate amount of industrial water or saturated steam into the reactive gas pipeline, causing the water to vaporize at high temperature, thus creating suitable partial pressures of carbon dioxide and water vapor in the reactive gas. The secondary nozzle is connected to the cooling gas and reactive gas through two independent gas branches. A regulating valve is installed on each branch, allowing the secondary nozzle to selectively inject only the cooling gas, only the reactive gas, or a mixture of both under the command of the control unit.

[0061] An infrared thermometer is installed downstream of the first parabolic trajectory within the granulation chamber, its field of view covering the flight path of the steel slag particles about to enter the secondary injection area. This device is used to detect the surface temperature of these particles at the end of the first parabolic trajectory. The temperature signal output by the infrared thermometer is sent to the control unit and compared with a preset temperature range determined in advance based on the steel slag composition, reaction kinetics, and system thermal balance. For example, the preset temperature range can be set between 500 and 800 degrees Celsius, which is higher than the minimum temperature required for the gas-solid reaction between carbon dioxide and free calcium oxide and free magnesium oxide, while avoiding excessively high temperatures that could lead to overly surface-level reaction and affect subsequent waste heat utilization. When the surface temperature of the steel slag particles is detected to be within the preset temperature range, the control unit sends an opening command to the secondary nozzle and adjusts the regulating valves of each branch to ensure that the reactive gas occupies a certain proportion of the gas injected by the secondary nozzle. An atmosphere containing carbon dioxide and water vapor is injected into the second parabolic trajectory area, allowing the particles to fully contact the reactive gas within this temperature window. During this process, the free calcium oxide and free magnesium oxide on the surface of the high-temperature particles undergo hydration and carbonation reactions with water vapor and carbon dioxide to generate volume-stable hydroxides and carbonates, which allows the potential for later expansion to be released and dissolved in advance during the flight phase.

[0062] Conversely, when the infrared thermometer detects that the particle surface temperature is below the lower limit of the preset temperature range, the control unit determines that the current temperature is insufficient to support an effective gas-solid reaction. Continuing to inject reactive gas would not only fail to achieve a significant dissipation effect but would also cause unnecessary cooling, further lowering the particle temperature and reducing the heat grade when entering the grate cooler and waste heat recovery device. Therefore, in this situation, the control unit shuts off the secondary nozzles and / or supplies cooling gas only to the secondary nozzles, ensuring that the slag particles only receive limited aerodynamic forces and sensible heat transfer without additional reactive cooling. This atmosphere selection mechanism, triggered by surface temperature, ensures that reactive gas is introduced into the second parabolic flight zone only when the slag particles are within a suitable temperature window. This maximizes the dissipation of free calcium oxide and free magnesium oxide with limited gas consumption, while avoiding excessive cooling and heat waste at low temperatures. Combined with the second parabolic flight path formed by secondary injection in the above implementation, this limitation allows the steel slag particles to obtain a spatiotemporally controllable reaction area inside the granulation chamber. This not only increases the contact time between the particles and carbon dioxide and water vapor in the medium and high temperature range, but also ensures that the reaction takes place under the most favorable thermal conditions through temperature triggering logic. Thus, while maintaining the overall waste heat recovery efficiency, it significantly improves the volume stability of the steel slag particles and the subsequent resource utilization performance.

[0063] Optionally, the steel slag product is sampled within a preset time period to detect the free calcium oxide content and / or volume expansion rate in the steel slag particles, and compared with the preset stability target range to obtain the stability deviation; simultaneously, the steam pressure and / or steam flow rate generated during the waste heat recovery process are detected and compared with the preset steam demand to obtain the energy utilization deviation; based on the stability deviation and energy utilization deviation, the processing conditions are divided into an energy utilization priority mode and a stability priority mode. In the energy utilization priority mode, the total flow rate and / or mass fraction of the reactive gas injected by the secondary nozzle is limited and / or the secondary nozzle is closed, so that the steel slag particles mainly fly along the first parabolic trajectory and are cooled by the cooling gas; in the stability priority mode, the secondary nozzle is opened and the proportion of reactive gas in the injected gas is increased, so that the flight time of the steel slag particles in the second parabolic trajectory and the degree of contact with the atmosphere containing carbon dioxide and water vapor are increased.

[0064] It should be noted that the temperature rise trend refers to the direction of temperature change obtained by analyzing the time-series temperature data after the multi-point infrared thermometer continuously measures the steel slag particles at different positions along the second parabolic flight trajectory. As the particles move along the second parabolic trajectory, the multi-point infrared thermometer sequentially transmits the surface temperature data of the particles at the beginning, middle, and end of the flight path to the control unit. The control unit performs sequential comparisons of the acquired temperature data, such as comparing the temperature difference between the beginning and middle of the flight path, or comparing the temperature difference between the middle and end of the flight path. When the temperature rises in two consecutive flight positions, i.e., the surface temperature gradually increases as the flight progresses, it can be determined that the particles exhibit a temperature rise trend. This trend is usually caused by the rapid conduction of residual heat from the inside of the steel slag particles to the surface, or it may be caused by an exothermic reaction between reactive gases and the particle surface. Under the premise of a relatively stable environment in the granulation chamber and a basically constant temperature of the injected gas, the temperature rise trend of the particles during flight is considered an indicator of heat migration from the inside of the particles to the surface.

[0065] While the steel slag particles are still on their second parabolic flight path and their temperature is trending upward, the control unit promptly closes the regulating valve of the cooling gas branch to prevent the cooling gas from causing additional cooling to the particle surface. This is because if cooling gas continues to be injected while residual heat inside the particles is being conducted to the surface, a strong cooling gradient will form on the outer surface, causing the outer temperature to drop faster than the internal heat transfer rate. This not only weakens the utilization efficiency of internal heat but also locks some of the untransferred usable heat inside the particles, ultimately releasing it with a lower temperature difference after the particles fall into the grate cooler, which is detrimental to the concentrated recovery of waste heat on the gas phase side. By stopping the injection of cooling gas during the particle temperature rise, the particle surface can be maintained at a temperature close to the internal temperature, allowing more of the residual sensible heat inside to be carried away by the reactive gas or surrounding gas through convection, thereby increasing the recovery rate of gas phase waste heat.

[0066] As the particle temperature continues to rise, the control unit maintains the injection of reactive gas. At this time, the particle surface temperature is rapidly increasing due to internal thermal migration, falling within a temperature range conducive to the hydration reaction of free calcium oxide with water vapor and the carbonation reaction with carbon dioxide. Without interference from cooling gas, the injected reactive gas can more fully contact the high-temperature particle surface, increasing the reaction rate and promoting a more uniform reaction into the particle interior. Since the reactive gas's primary objective is not temperature reduction but stability improvement, maintaining its supply further enhances the volumetric stability of the particles without significantly reducing their temperature.

[0067] In summary, by shutting off the cooling gas while maintaining the supply of the reactive gas when the particle temperature is rising, the following continuous effects can be achieved: the internal residual heat is transferred more fully to the gas phase, improving the efficiency of gas phase waste heat recovery; hydration and carbonation reactions are promoted under high-temperature surface conditions, further enhancing the particle volume stability; and the intervention of the cooling gas at inappropriate stages is avoided, resulting in heat dispersion and more intensive utilization of thermal energy within the entire granulation chamber.

[0068] In other embodiments, the temperature rise trend can also be determined by setting two infrared temperature measurement points on the second parabolic trajectory and directly determining the trend based on the temperature difference between the two measurement points; or by using a high-temperature thermal imager to obtain the temperature field changes during particle flight, and replacing point-by-point comparison with the direction of regional average temperature change in the control unit. As long as the control idea of ​​dynamically switching between cooling gas and reactive gas based on the temperature change trend of particle surface is met, it belongs to the equivalent method of this limitation.

[0069] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A processing technology for energy recovery from steel slag, characterized in that, include: Liquid steel slag is atomized and cooled by a high-speed airflow to form high-temperature steel slag particles, and the first high-temperature flue gas is generated. The steel slag particles are conveyed and cooled by a cooling medium to reduce their temperature to a preset temperature, and a second high-temperature flue gas is discharged during the cooling process. The heat from the first high-temperature flue gas and / or the second high-temperature flue gas is recovered and utilized. The recycled first high-temperature flue gas and / or the second high-temperature flue gas are at least partially reused as the cooling medium.

2. The processing technology for energy recovery from steel slag resource utilization according to claim 1, characterized in that, The high-speed airflow contains water vapor to promote the decomposition of free calcium oxide and free magnesium oxide in the liquid steel slag.

3. The processing technology for energy recovery from steel slag resource utilization according to claim 1, characterized in that, The process of atomizing and cooling liquid steel slag through a high-speed airflow to form high-temperature steel slag particles includes: Liquid steel slag is atomized by a high-speed airflow, and the resulting steel slag droplets enter the granulation chamber with a parabolic trajectory. The droplets are cooled and solidified in the granulation chamber to form high-temperature steel slag particles, which are then discharged from the outlet of the granulation chamber. The first high-temperature flue gas is collected through the flue gas outlet of the granulation chamber.

4. The processing technology for energy recovery from steel slag resource utilization according to claim 3, characterized in that, The temperature of the steel slag particles discharged from the outlet of the granulation chamber is 350℃~850℃.

5. The processing technology for energy recovery from steel slag resource utilization according to claim 4, characterized in that, The temperature of the steel slag particles discharged from the outlet of the granulation chamber is 500℃~600℃.

6. The processing technology for energy recovery from steel slag resource utilization according to claim 1, characterized in that, Cooling steel slag particles using a cooling medium includes: Multiple cooling zones are sequentially arranged along the conveying direction of the steel slag particles. Cooling media are sequentially supplied to the steel slag particles through each cooling zone, so that the temperature of the steel slag particles decreases step by step.

7. The processing technology for energy recovery from steel slag resource utilization according to claim 6, characterized in that, The steel slag particles are transported via a grate cooler.

8. The processing technology for energy recovery from steel slag according to claim 6, characterized in that, The second high-temperature flue gas includes multiple streams of flue gas generated by each of the cooling zones, and each stream of flue gas is collected and recycled.

9. The processing technology for energy recovery from steel slag resource utilization according to claim 6, characterized in that, In the conveying direction of the steel slag particles, the temperature of the cooling medium in the cooling zone at the end is lower than that in any of the other cooling zones.

10. A processing system for energy recovery from steel slag, characterized in that, include: The granulation device is used to atomize and cool liquid steel slag through a high-speed airflow to form high-temperature steel slag particles and generate the first high-temperature flue gas. A grate cooler is used to transport the steel slag particles and cool them through a cooling medium to reduce the temperature of the steel slag particles to a preset temperature, and to discharge a second high-temperature flue gas during the cooling process. Waste heat recovery device, used to recover and utilize the heat of the first high-temperature flue gas and / or the second high-temperature flue gas; A circulation device is used to recycle at least a portion of the recovered first high-temperature flue gas and / or the second high-temperature flue gas as the cooling medium.

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