Countercurrent immersion type thermal steel slag treatment coupling industrial flue gas carbon capture system and method

Abstract

The invention discloses a countercurrent immersion type thermal steel slag treatment coupling industrial flue gas carbon capture system and method, and belongs to the technical field of industrial solid waste and waste gas resourceful treatment. The system comprises a hot braising pool, a slag cover, a matrix type water and gas distribution system, an industrial flue gas supply unit, a micro-nano bubble generation device, a waste heat recovery device and a control unit, the method comprises the following steps: introducing cooling water and an industrial flue gas aqueous solution rich in micro-nano bubbles into the hot-state steel slag from the bottom of the tank in a zoning and timing sequence manner through the matrix type water and gas distribution system, and sequentially carrying out countercurrent immersion type cooling slag braising and carbonation carbon sequestration reaction. According to the invention, the problems of poor safety, low resource recovery rate and high carbon capture cost of the traditional hot braising process are solved, and a safe, efficient and low-cost steel slag and flue gas synergistic treatment solution is provided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of industrial solid waste and waste gas resource processing, in particular, relates to a countercurrent immersion type hot steel slag processing coupled industrial flue gas carbon capture system and method. BACKGROUND

[0002] Steel slag is the main solid waste produced in the steel smelting process, and its output is about 12%-15% of the crude steel output. A large amount of steel slag stored not only occupies land, but also is easy to expand in volume when it comes into contact with water due to the presence of free calcium oxide and free magnesium oxide, resulting in poor stability and difficulty in large-scale resource utilization in the building material field.

[0003] At present, the most widely used steel slag treatment process is hot stewing method, that is, by spraying water on high-temperature steel slag, the steel slag is pulverized by using its digestion to eliminate expansion stress, and the free calcium oxide and free magnesium oxide are stabilized. However, the existing hot stewing process, whether it is a pool type hot stewing or a tank type pressure hot stewing, has significant defects. The pool type hot stewing usually adopts a top water spraying method, which has the problems of large water consumption, long processing cycle (usually more than 20 hours), poor workshop environment, and a large amount of dust-containing steam and combustible gases such as hydrogen, carbon monoxide generated during the water spraying process, which has the risk of explosion. Although the tank type pressure hot stewing is carried out in a sealed pressure tank, the reaction is accelerated by maintaining a certain pressure, which shortens the processing time, but the equipment investment is huge (a single set of equipment often costs tens of millions of yuan), the manufacturing and maintenance requirements for the pressure vessel are extremely high, there is a risk of overpressure explosion during operation, and the risk of combustible gas explosion cannot be solved.

[0004] On the other hand, the steel industry itself is also a huge source of carbon dioxide emissions, and the industrial flue gas generated in the sintering, coking, lime calcination and other links contains a certain concentration of carbon dioxide (usually 10%-30%). How to capture and utilize the carbon dioxide in these flue gases at low cost and high efficiency is a key challenge to achieve carbon emission reduction in the steel industry. Existing carbon capture technologies such as amine absorption have the problems of high capture cost, high energy consumption, and easy degradation of the absorbent, which are difficult to be widely applied.

[0005] It is worth noting that steel slag contains a large amount of alkaline substances such as calcium and magnesium, which is a natural carbon dioxide mineralizer. In theory, carbon dioxide in industrial flue gas can be fixed by using steel slag to achieve "waste treatment with waste". However, the attempt to combine steel slag treatment and carbon capture in existing technologies is still in its early stages. The usual practice is to contact the cooled slag with carbon dioxide in a reactor, which has a slow reaction rate and low carbon fixation efficiency, and fails to utilize the high activity of hot steel slag, resulting in poor economic efficiency. If carbon dioxide is directly introduced during the high-temperature stewing process, there are safety problems such as easy oxidation of metallic iron at high temperature, resulting in a decrease in iron recovery rate, and an increase in the risk of combustible gas explosion.

[0006] Therefore, developing an integrated technology system capable of synergistically solving the problems of efficient and stable treatment of hot steel slag, inhibition of metal iron oxidation to improve recovery rate, safe and efficient capture of industrial flue gas carbon dioxide, and recovery of process waste heat has become a key problem in the field that needs to be solved. SUMMARY

[0007] The present application aims to overcome a series of outstanding problems and limitations in the existing steel slag hot stew technology, including: 1. High safety risk: In traditional pool-type hot stew and tank-type hot stew processes, high-temperature water is easy to produce hydrogen and carbon monoxide, etc. Combustible gases, and there is a risk of explosion. 2. Low resource recovery rate: In the existing process, the high-temperature water vapor environment leads to serious oxidation of metal iron, reducing the iron recovery rate in the subsequent magnetic separation process; at the same time, the sensible heat of steel slag and the carbon source in flue gas are not effectively utilized, resulting in energy waste and carbon emissions. 3. Uneven treatment effect: The traditional water distribution method is easy to produce hydraulic dead zones, resulting in uneven cooling of steel slag, poor pulverization effect, and incomplete digestion of free calcium and magnesium. 4. High cost of carbon capture: The investment and operating cost of the independent carbon capture system is high, and it is difficult to be organically coupled with the steel production process.

[0008] Therefore, the present application provides a countercurrent immersed hot steel slag treatment coupled with an industrial flue gas carbon capture system and method, which aims to innovatively integrate steel slag stabilization treatment, iron resource recovery, industrial flue gas carbon capture, and waste heat recovery into one, achieving safe, efficient, and low-cost collaborative production.

[0009] To solve the above technical problems, the present application adopts the following technical solutions: The countercurrent immersed hot steel slag treatment coupled with an industrial flue gas carbon capture system comprises a hot stew pool, a slag cover, a matrix-type water and gas distribution system, an industrial flue gas supply unit, a micro-nano bubble generating device, a waste heat recovery device, and a control unit. The slag cover is tightly closed and installed at the top end of the hot stew pool, the matrix-type water and gas distribution system is laid at the bottom of the inner cavity of the hot stew pool, the water inlet of the micro-nano bubble generating device is connected to a water source, the gas inlet of the micro-nano bubble generating device is connected to the industrial flue gas supply unit, and the water outlet of the micro-nano bubble generating device is connected to the matrix-type water and gas distribution system.

[0010] Further, the hot stew pool is of a rectangular structure for containing hot steel slag, the bottom of the hot stew pool is of a bucket-shaped structure, the bottom end of the bucket-shaped structure is provided with a drain port, a drain pipe is connected to the drain port, and a switch valve is installed on the drain pipe; the side of the hot stew pool is provided with a ventilation replacement device.

[0011] Furthermore, an exhaust vent is provided in the middle of the slag cover, and the exhaust vent is connected to the waste heat recovery device through an exhaust pipe; a serpentine water-cooled pipe is installed inside the slag cover, and an infrared thermometer, a pressure sensor, and a gas concentration sensor are installed on the slag cover; there are multiple infrared thermometers, which are distributed and installed on the inner surface of the slag cover, and the pressure sensor and gas concentration sensor are set near the exhaust vent; a slag cover opening and closing drive mechanism is connected to the side of the slag cover.

[0012] Furthermore, the upper part of the matrix water and air distribution system is covered with a perforated high-temperature resistant steel billet. The matrix water and air distribution system includes two main water supply pipes, multiple water distribution branch pipes, and multiple regulating valves respectively installed on each of the water distribution branch pipes; the main water supply pipes are connected to the outlet of the micro-nano bubble generator.

[0013] Furthermore, the water distribution branch pipe is made of heat-resistant stainless steel or high-temperature alloy, and is provided with a water distribution port with an equivalent diameter of not less than 10mm; the water distribution port is made of high-performance ceramic material and is fixed by a quick-disassembly connection method.

[0014] Furthermore, the industrial flue gas supply unit includes a dust collector, an induced draft fan, and a carbon dioxide concentration monitor arranged sequentially along the airflow direction.

[0015] Furthermore, the control unit is connected to the infrared thermometer, pressure sensor, gas concentration sensor, various regulating valves, industrial flue gas supply unit, micro-nano bubble generator and slag cover opening and closing drive mechanism. The control unit is configured to perform the following operations: (a) Based on the data from the pressure sensor, the sequential start-stop mode is activated within the safe pressure range, and the regulating valves on different water distribution branches are started and stopped in turn according to the preset sequence to introduce cooling water; (b) Based on the data from the infrared thermometer, when a local high-temperature area is detected, the zone control mode is activated, and the opening of the corresponding area regulating valve is opened or increased first. (c) When the infrared thermometer detects that the temperature in each area of ​​the hot bath has dropped below 548°C, start the industrial flue gas supply unit and the micro-nano bubble generator, randomly start and stop some regulating valves, and introduce industrial flue gas aqueous solution rich in micro-nano bubbles. (d) When the gas concentration sensor detects that the concentration of hydrogen or carbon monoxide exceeds 25% of the lower explosive limit, the safety interlock is triggered, and the operation of the industrial flue gas supply unit and the micro-nano bubble generator is immediately cut off. (e) After the slag curing process is completed, continuously monitor the data from the infrared thermometer and the gas concentration sensor, and only allow or control the slag cover opening and closing drive mechanism to open the slag cover when the following two conditions are met simultaneously: (i) The readings at all temperature monitoring points dropped below 100°C; (ii) The gas concentration sensor readings show that the concentrations of both hydrogen and carbon monoxide are below 1% of their lower explosive limits; The control unit is also configured to: when condition (e)(i) is met but condition (e)(ii) is not met, control the activation of the ventilation and replacement device to purge the pool with inert gas or air until condition (e)(ii) is met.

[0016] A countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture method is proposed. The above system is used to introduce cooling water and industrial flue gas aqueous solution rich in micro-nano bubbles into the hot steel slag from the bottom of the pool in a phased and sequential manner through a matrix water and gas distribution system. The countercurrent submerged cooling and slag curing and carbonation carbon fixation reactions are carried out in sequence.

[0017] A countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture method includes the following steps: (a) Slag loading and sealing: Hot steel slag is loaded into the hot quenching tank and the slag cover is closed; (b) Countercurrent immersion cooling: The control unit reads the pressure sensor data. If the pressure value is normal, the sequential start-stop mode is activated, and the regulating valves are opened and closed in sequence to introduce cooling water; cooling water is introduced from the bottom of the hot braising tank for steam braising of slag. (c) Coupled carbon capture: The control unit continuously monitors the data from the infrared thermometer. When the temperature in all areas drops below 548°C, the industrial flue gas supply unit and the micro-nano bubble generator are activated to introduce an industrial flue gas aqueous solution rich in micro-nano bubbles for carbonation reaction. If the infrared thermometer detects a local temperature rise, the zone control mode is automatically triggered for local enhanced cooling. The gas concentration sensor provides safety interlock protection throughout the process. (d) Waste heat recovery and drainage: The high-temperature waste gas generated during the treatment process is introduced into the waste heat recovery device through the exhaust port for heat recovery and purification; after the reaction is completed, the control valve is used to discharge the leaching water through the drain port and drainage pipe. (e) Safe slag removal: The control unit continuously monitors the state inside the pool and only issues an instruction to open the slag cover after confirming that the temperature of the steel slag is ≤100℃ and the concentration of combustible gas in the pool is close to zero. (f) Remove the cooled slag after processing.

[0018] Furthermore, the industrial flue gas introduced in step (c) comes from a steel plant sintering machine or lime kiln, and its carbon dioxide volume concentration ranges from 10% to 30%; the carbon dioxide mass concentration of the industrial flue gas aqueous solution rich in micro-nano bubbles is maintained in the range of 500 mg / L to 1500 mg / L. The heat energy recovered by the waste heat recovery device in step (d) is used to drive the steam turbine generator set, and part of the generated electricity is used to drive the induced draft fan and system water pump in the industrial flue gas supply unit. In step (e), if the concentration of combustible gas does not meet the standard, the ventilation and replacement procedure will be automatically started to purge and dilute the pool with inert gas until the concentration is safe before the cover is allowed to be opened. After the steel slag is treated in step (f), with the help of a reasonable secondary magnetic separation process, the metallic iron content in the tailings can be controlled to below 1%, the carbon dioxide capture rate is ≥15%, and the free calcium oxide content is ≤1.5%. The micro-nano bubble generator is not activated in step (b), but is activated only in step (c) after the temperature inside the pool drops below 548°C.

[0019] Compared with the prior art, the present invention, by adopting the above technical solution, has the following advantages: Safe and efficient: It adopts a phased strategy of cooling with water first and then carbon fixation at low temperature, and injects carbon dioxide in a safe temperature window below 548℃, which completely avoids the risk of producing combustible gases and violent oxidation of metal iron by water-gas reaction at high temperature. At the same time, the maintenance of a slightly positive pressure environment prevents the entry of external air, thus fundamentally eliminating the risk of explosion.

[0020] High resource recovery rate: The countercurrent immersion method ensures full contact between water, gas, and steel slag, while micro-nano bubble technology greatly increases the mass transfer efficiency and reaction time of carbon dioxide. Combined with a reasonable steel slag magnetic separation process, the MFe content in the tailings can be controlled below 1%, and the carbon dioxide capture rate in the flue gas can be no less than 15%, achieving efficient recovery of iron resources and high-value carbon sources.

[0021] Excellent treatment effect: Cooling water is introduced into the hot steel slag from the bottom of the pool in a phased and sequential manner through a matrix water and air distribution system, ensuring that there are no dead zones in the reaction. After treatment, the steel slag is fully pulverized (≤30mm particles ≥75%) and has excellent stability (free calcium oxide ≤1.5%), making it a high-quality building material raw material.

[0022] Waste-to-waste treatment, cost reduction and efficiency improvement: By directly utilizing low-concentration carbon dioxide industrial flue gas (such as sintering flue gas and lime kiln tail gas) within the steel plant as a carbon source, waste-to-waste treatment is achieved, eliminating the high-cost carbon dioxide purification and compression process and significantly reducing carbon capture costs. At the same time, the system's waste heat is recovered for power generation or to drive its own equipment, reducing overall energy consumption.

[0023] Product value enhancement: The treated steel slag has good stability, with free calcium oxide content ≤1.5%, carbon dioxide capture rate ≥15%, and is fully pulverized. It can be directly used as high-quality building material aggregate or cement admixture, realizing high-value-added resource utilization of solid waste.

[0024] Intelligent and reliable: Intelligent control strategies based on multi-sensor data (sequential start-stop, zoned control) ensure uniform, efficient and reliable response.

[0025] Environmentally friendly: The entire process achieves the coordinated treatment of waste residue and waste gas.

[0026] This invention innovatively integrates three independent processes—steel slag treatment, carbon capture, and waste heat recovery—into a single, safe, economical, efficient, and green comprehensive solution, providing strong technical support for energy conservation, carbon reduction, and solid waste resource utilization in the steel industry.

[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a side view of the hot braising tank; Figure 3 yes Figure 2 Sectional view at point AA; Figure 4 yes Figure 2 Sectional view at point BB; Figure 5 This is a top view of the slag lid; Figure 6 This is a bottom view of the hot brine tank; Figure 7 This is a structural diagram of a matrix-type water and air distribution system.

[0029] In the diagram, 1-Hot curing tank, 11-Drain outlet, 12-Drainage pipe, 13-Switch valve; 2-Slag cover, 21-Exhaust vent, 22-Water cooling pipe, 23-Infrared thermometer, 24-Pressure sensor, 25-Gas concentration sensor, 26-Exhaust pipe; 3-Matrix water and gas distribution system, 31-Perforated high-temperature resistant steel billet, 32-Main water supply pipe, 33-Water distribution branch pipe, 34-Regulating valve, 35-Water distribution port; 4-Industrial flue gas supply unit, 41-Dust collector, 42-Exhaust fan, 43-Carbon dioxide concentration monitor; 5-Micro-nano bubble generator; 6-Waste heat recovery device; 7-Control unit; 8-Slag cover opening and closing drive mechanism; 9-Ventilation replacement device; 10-Magnetic separator. Detailed Implementation

[0030] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0031] like Figures 1-7As shown in the figure, the present invention provides a countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture system, including a hot blanching tank 1, a slag cover 2, a matrix water and gas distribution system 3, an industrial flue gas supply unit 4, a micro-nano bubble generator 5, a waste heat recovery device 6, and a control unit 7. The slag cover 2 is sealed and fastened to the top of the hot blanching tank 1. The matrix water and gas distribution system 3 is laid at the bottom of the inner cavity of the hot blanching tank 1. The water inlet of the micro-nano bubble generator 5 is connected to a water source. The air inlet of the micro-nano bubble generator 5 is connected to the industrial flue gas supply unit 4. The water outlet of the micro-nano bubble generator 5 is connected to the matrix water and gas distribution system 3.

[0032] The hot curing tank 1 has a rectangular structure and is used to contain hot steel slag. The bottom of the hot curing tank 1 has a bucket-shaped structure, and a drain outlet 11 is provided at the bottom of the bucket-shaped structure. A drain pipe 12 is connected to the drain outlet 11, and a switch valve 13 is installed on the drain pipe 12.

[0033] An exhaust vent 21 is located in the middle of the slag cover 2, and the exhaust vent 21 is connected to the waste heat recovery device 6 through an exhaust pipe 26. The flue gas after waste heat recovery is treated by the subsequent flue gas purification system and then discharged through the chimney.

[0034] The inside of the slag cover 2 is equipped with a serpentine water-cooled pipe 22, and the slag cover 2 is equipped with an infrared thermometer 23, a pressure sensor 24, and a gas concentration sensor 25.

[0035] Multiple infrared thermometers 23 are distributed and installed on the inner surface of the slag cover 2 to monitor the temperature distribution of the steel slag surface in different areas of the hot curing pool 1.

[0036] Pressure sensor 24 and gas concentration sensor 25 are distributed on both sides of the vent 21 on the slag cover 2, and are positioned close to the vent 21. Pressure sensor 24 is used to monitor the internal pressure of the hot blanching tank 1, and gas concentration sensor 25 is used to monitor the concentration of hydrogen and / or carbon monoxide.

[0037] The slag cover 2 is connected to a slag cover opening and closing drive mechanism 8 on its side.

[0038] The matrix-type water and air distribution system 3 is topped with a perforated high-temperature resistant steel billet 31. The system includes two main water supply pipes 32, multiple branch water distribution pipes 33, and multiple regulating valves 34 respectively installed on each branch water distribution pipe 33. The main water supply pipes 32 are connected to the outlet of the micro / nano bubble generator 5. Each branch water distribution pipe 33 is made of heat-resistant stainless steel or a high-temperature alloy and has a water distribution port 35 with an equivalent diameter of not less than 10 mm. The water distribution port 35 is made of high-performance ceramic material and is fixed using a quick-detachable connection method.

[0039] The air inlet of the industrial flue gas supply unit 4 is connected to the industrial kiln flue gas source. The industrial flue gas supply unit 4 includes a dust collector 41, an induced draft fan 42 and a carbon dioxide concentration monitor 43 arranged sequentially along the airflow direction.

[0040] The micro-nano bubble generator 5 is located outside the hot brine tank 1 and is used to generate flue gas aqueous solution rich in micro-nano bubbles.

[0041] The hot braising tank 1 is equipped with a ventilation and displacement device 9 on its side, which can blow inert gas or air into the hot braising tank 1 for purging.

[0042] The cooled slag after being treated in the hot blanching tank 1 enters the magnetic separator 10 for sorting.

[0043] The control unit 7 is connected to the infrared thermometer 23, pressure sensor 24, gas concentration sensor 25, various regulating valves 34, industrial flue gas supply unit 4, micro-nano bubble generator 5, and slag cover opening and closing drive mechanism 8.

[0044] The control unit 7 is connected to the carbon dioxide concentration monitor 43. The control unit 7 can dynamically adjust the gas-liquid mixing ratio of the micro-nano bubble generator 5 according to the actual concentration of carbon dioxide in the industrial flue gas.

[0045] The control unit 7 is configured to perform the following operations: (a) Based on the data from the pressure sensor 24, the sequential start-stop mode is activated within the safe pressure range, and the regulating valves 34 on different water distribution branch pipes 33 are started and stopped in turn according to the preset sequence to introduce cooling water; (b) Based on the data from the infrared thermometer 23, when a local high-temperature area is detected, the zone control mode is activated, and the opening of the corresponding zone regulating valve 34 is opened or increased first. (c) When the infrared thermometer 23 detects that the temperature in each area of ​​the hot bath 1 has dropped below 548°C, the industrial flue gas supply unit 4 and the micro-nano bubble generator 5 are started, and some regulating valves 34 are randomly started and stopped to introduce industrial flue gas aqueous solution rich in micro-nano bubbles. (d) When the gas concentration sensor 25 detects that the concentration of hydrogen or carbon monoxide exceeds 25% of the lower explosive limit (LEL), the safety interlock is triggered, and the operation of the industrial flue gas supply unit 4 and the micro-nano bubble generator 5 is immediately cut off. (e) After the slag curing process is completed, continuously monitor the data from the infrared thermometer 23 and the gas concentration sensor 25, and only allow or control the slag cover opening and closing drive mechanism 8 to open the slag cover 2 when the following two conditions are met simultaneously: (i) The readings at all temperature monitoring points dropped below 100°C; (ii) The readings of gas concentration sensor 25 show that the concentrations of hydrogen and carbon monoxide are both below 1% of their lower explosive limits.

[0046] The control unit 7 is further configured to: when condition (e)(i) is met but condition (e)(ii) is not met, control the activation of the ventilation and displacement device 9 to blow inert gas or air into the pool for purging until condition (e)(ii) is met.

[0047] A method for countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture using the above system involves introducing cooling water and an aqueous solution of industrial flue gas rich in micro-nano bubbles into the hot steel slag from the bottom of the pool in a zoned and sequential manner through a matrix-type water and gas distribution system. This sequentially performs countercurrent submerged cooling and slag-curing reactions, as well as carbonation and carbon fixation reactions. Specifically, the method includes the following steps: (a) Slag loading and sealing: Hot steel slag is loaded into the hot quenching tank 1 and the slag cover 2 is closed; (b) Countercurrent immersion cooling: The control unit 7 reads the data from the pressure sensor 24. If the pressure value is normal, the sequential start-stop mode is activated, and the regulating valves 34 are opened and closed in sequence to introduce cooling water. Cooling water is introduced from the bottom of the hot braising tank 1 to steam the slag. (c) Coupled carbon capture: The control unit 7 continuously monitors the data of the infrared thermometer 23. When the temperature of all areas drops below 548°C, the industrial flue gas supply unit 4 and the micro-nano bubble generator 5 are activated to introduce an industrial flue gas aqueous solution rich in micro-nano bubbles for carbonation reaction. If the infrared thermometer 23 detects a local temperature rise, it automatically triggers the zone control mode for local enhanced cooling. The gas concentration sensor 25 provides safety interlock protection throughout the process. (d) Waste heat recovery and drainage: The high-temperature waste gas generated during the treatment process is introduced into the waste heat recovery device 6 through the exhaust port 21 for heat recovery and purification; after the reaction is completed, the control switch valve 13 discharges the leaching water through the drain port 11 and the drainage pipe 12. (e) Safe slag removal: The control unit 7 continuously monitors the state inside the pool and only issues an instruction to open the slag cover 2 after confirming that the temperature of the steel slag is ≤100℃ and the concentration of combustible gas in the pool is close to zero. (f) Remove the cooled slag after processing.

[0048] The industrial flue gas introduced in step (c) comes from a steel plant sintering machine or lime kiln, and its carbon dioxide volume concentration ranges from 10% to 30%; the carbon dioxide mass concentration of the industrial flue gas aqueous solution rich in micro-nano bubbles is maintained in the range of 500 mg / L to 1500 mg / L.

[0049] The heat energy recovered by the waste heat recovery device 6 in step (d) is used to drive the steam turbine generator set, and the generated electrical energy is used to drive the induced draft fan 42 and the system water pump in the industrial flue gas supply unit 4.

[0050] In step (e), if the concentration of combustible gas does not meet the standard, the ventilation and replacement procedure will be automatically started to purge and dilute the pool with inert gas until the concentration is safe before the cover is allowed to be opened.

[0051] After the steel slag is treated in step (f), with the help of a reasonable secondary magnetic separation process, the content of metallic iron (MFe) in the tailings can be controlled to below 1%, the carbon dioxide capture rate is ≥15%, and the free calcium oxide content is ≤1.5%.

[0052] The micro-nano bubble generator 5 is not activated in step (b), but is activated only in step (c) after the temperature inside the pool drops below 548°C.

[0053] Example 1: Treatment of converter steel slag and coupling with sintering flue gas Object to be processed: 150 tons of hot converter steel slag.

[0054] Carbon source: flue gas from the sintering machine of the steel plant, with a carbon dioxide volume concentration of about 20%, used after dust removal.

[0055] Process parameters: After the steel slag is added to the tank, room temperature water is immediately introduced from the bottom at a flow rate controlled at 15 m³ / h for countercurrent immersion cooling. When the infrared thermometer on the slag cover shows that the temperature inside the tank has dropped to 530℃, the micro / nano bubble generator is activated. Sintering flue gas is introduced at a flow rate of 50 Nm³ / h and mixed with 25 m³ / h of water to generate an aqueous solution rich in micro / nano bubbles (median diameter 100 μm) (carbon dioxide mass concentration approximately 1000 mg / L), which is then continuously introduced. A slight positive pressure is maintained in the tank at 0.5 kPa. The total treatment time is approximately 5.5 hours.

[0056] Treatment results: After treatment, the free calcium oxide content in the steel slag decreased to 1.1%; the carbon dioxide capture rate reached 15.9%; and the pulverization rate of particles ≤30mm reached 78.4%. After magnetic separation, the metallic iron content in the tailings decreased to 0.9%.

[0057] Example 2: Treatment of electric arc furnace steel slag and coupling with lime kiln exhaust gas Object to be processed: 80 tons of hot steel slag from electric arc furnace.

[0058] Carbon source: Lime kiln exhaust gas, with a carbon dioxide volume concentration of about 28%, which is relatively pure and only requires simple dust removal.

[0059] Process parameters: Initial water flow rate 10 m³ / h; when the temperature drops to 540℃, lime kiln tail gas is introduced at a flow rate of 30 Nm³ / h and mixed with water (20 m³ / h) to prepare a micro-nano bubble aqueous solution (carbon dioxide mass concentration approximately 1400 mg / L). Total treatment time is approximately 6 hours.

[0060] Treatment results: After treatment, the free calcium oxide content in the steel slag decreased to 1.1%; the carbon dioxide capture rate reached 16.8%. The metallic iron content in the tailings decreased to 0.9%.

[0061] Comparative Example 1: Traditional pool-type hot braising process Object of treatment: 150 tons of converter steel slag from the same source as in Example 1.

[0062] Process: Top spraying method is adopted, with a flow rate controlled at 15m³ / h and a treatment cycle of up to 15 hours.

[0063] Results: The free calcium oxide content in the steel slag decreased to 2.8% after treatment, with no carbon fixation effect. The metallic iron content in the tailings was 2.6%. The hydrogen concentration during treatment was close to the lower explosive limit, posing a significant safety hazard. No waste heat was recovered during the treatment process, resulting in complete energy waste.

[0064] Comparative Example 2: Pressurized Tank Heat Curing Process Object of treatment: 150 tons of converter steel slag from the same source as in Example 1.

[0065] Process: The treatment is carried out in a closed pressure tank, using a top spray method, with the flow rate controlled at 15 m³ / h and the pressure maintained at 0.3 MPa. The treatment cycle is approximately 6 hours.

[0066] Treatment results: After treatment, the free calcium oxide content in the steel slag decreased to 2.3%, with no carbon fixation effect. The metallic iron content in the tailings was 1.4%. There is a tendency for combustible gas accumulation during operation, posing an explosion risk; strict pressure monitoring is required, resulting in a high safety risk. The carbon capture function was also not utilized.

[0067] The above description provides examples of the preferred embodiments of the present invention. Parts not detailed herein are common knowledge to those skilled in the art. The scope of protection of the present invention is determined by the claims. Any equivalent modifications based on the technical teachings of the present invention are also within the scope of protection of the present invention.

Claims

1. A counter-current submerged hot steel slag treatment coupled with an industrial flue gas carbon capture system, characterized in that: It includes a hot blanching tank (1), a slag cover (2), a matrix water and gas distribution system (3), an industrial flue gas supply unit (4), a micro-nano bubble generator (5), a waste heat recovery device (6), and a control unit (7); the slag cover (2) is sealed and fastened to the top of the hot blanching tank (1), the matrix water and gas distribution system (3) is laid at the bottom of the inner cavity of the hot blanching tank (1), the water inlet of the micro-nano bubble generator (5) is connected to a water source, the air inlet of the micro-nano bubble generator (5) is connected to the industrial flue gas supply unit (4), and the water outlet of the micro-nano bubble generator (5) is connected to the matrix water and gas distribution system (3).

2. The countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture system as described in claim 1, characterized in that: The hot brine tank (1) is a rectangular structure used to contain hot steel slag. The bottom of the hot brine tank (1) is a bucket-shaped structure with a drain outlet (11) at the bottom. A drain pipe (12) is connected to the drain outlet (11), and a switch valve (13) is installed on the drain pipe (12). A ventilation and displacement device (9) is installed on the side of the hot brine tank (1).

3. The countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture system as described in claim 1, characterized in that: The slag cover (2) is provided with an exhaust port (21) in the middle position. The exhaust port (21) is connected to the waste heat recovery device (6) through an exhaust pipe (26). A serpentine water-cooled pipe (22) is installed inside the slag cover (2). An infrared thermometer (23), a pressure sensor (24), and a gas concentration sensor (25) are installed on the slag cover (2). There are multiple infrared thermometers (23), which are distributed and installed on the inner surface of the slag cover (2). The pressure sensor (24) and the gas concentration sensor (25) are set near the exhaust port (21). The slag cover (2) is connected to the side of the slag cover (2) with a slag cover opening and closing drive mechanism (8).

4. The countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture system as described in claim 1, characterized in that: The matrix water and air distribution system (3) is covered with a perforated high-temperature resistant steel billet (31). The matrix water and air distribution system (3) includes two main water supply pipes (32), multiple water distribution branch pipes (33), and multiple regulating valves (34) respectively installed on each of the water distribution branch pipes (33). The main water supply pipes (32) are connected to the outlet of the micro-nano bubble generator (5).

5. The countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture system as described in claim 4, characterized in that: The water distribution branch pipe (33) is made of heat-resistant stainless steel or high-temperature alloy and is provided with a water distribution port (35) with an equivalent diameter of not less than 10 mm. The water distribution port (35) is made of high-performance ceramic material and is fixed by a quick-disassembly connection method.

6. The countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture system as described in claim 1, characterized in that: The industrial flue gas supply unit (4) includes a dust collector (41), an induced draft fan (42), and a carbon dioxide concentration monitor (43) arranged sequentially along the airflow direction.

7. The countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture system as described in claim 1, characterized in that: The control unit (7) is connected to the infrared thermometer (23), pressure sensor (24), gas concentration sensor (25), various regulating valves (34), industrial flue gas supply unit (4), micro-nano bubble generator (5) and slag cover opening and closing drive mechanism (8) via signal connection. The control unit (7) is configured to perform the following operations: (a) Based on the data from the pressure sensor (24), the sequential start-stop mode is activated within the safe pressure range, and the regulating valves (34) on different water distribution branch pipes (33) are started and stopped in turn according to the preset sequence to introduce cooling water; (b) Based on the data from the infrared thermometer (23), when a local high temperature area is identified, the zone control mode is activated, and the opening degree of the corresponding area regulating valve (34) is opened or increased first. (c) When the infrared thermometer (23) detects that the temperature of each area in the hot bath (1) has dropped below 548°C, the industrial flue gas supply unit (4) and the micro-nano bubble generator (5) are started, and some regulating valves (34) are randomly started and stopped to introduce industrial flue gas aqueous solution rich in micro-nano bubbles. (d) When the gas concentration sensor (25) detects that the concentration of hydrogen or carbon monoxide exceeds 25% of the lower explosive limit, the safety interlock is triggered, and the operation of the industrial flue gas supply unit (4) and the micro-nano bubble generator (5) is immediately cut off. (e) After the slag curing process is completed, continuously monitor the data from the infrared thermometer (23) and the gas concentration sensor (25), and only allow or control the slag cover opening and closing drive mechanism (8) to perform the operation of opening the slag cover (2) when the following two conditions are met simultaneously: (i) The readings at all temperature monitoring points dropped below 100°C; (ii) The readings of the gas concentration sensor (25) show that the concentrations of hydrogen and carbon monoxide are both below 1% of their lower explosive limits; The control unit (7) is also configured to: when condition (e)(i) is met but condition (e)(ii) is not met, control the activation of the ventilation replacement device (9) to blow inert gas or air into the pool for purging until condition (e)(ii) is met.

8. A counter-current submerged hot steel slag treatment coupled with industrial flue gas carbon capture method, using the counter-current submerged hot steel slag treatment coupled with industrial flue gas carbon capture system as described in any one of claims 1 to 7, characterized in that: The matrix-type water and gas distribution system introduces cooling water and industrial flue gas aqueous solution rich in micro-nano bubbles into the hot steel slag from the bottom of the pool in a zoned and sequential manner, so as to carry out countercurrent submerged cooling slag curing and carbonation carbon fixation reaction in sequence.

9. The countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture method as described in claim 8, characterized in that: Includes the following steps: (a) Slag filling and sealing: Hot steel slag is loaded into the hot quenching tank (1), and the slag cover is closed (2). (b) Countercurrent immersion cooling: The control unit (7) reads the data from the pressure sensor (24). If the pressure value is normal, the sequential start-stop mode is started, and the regulating valves (34) are opened and closed in sequence to introduce cooling water; cooling water is introduced from the bottom of the hot braising tank (1) to steam the slag. (c) Coupled carbon capture: The control unit (7) continuously monitors the data of the infrared thermometer (23). When the temperature of all areas drops below 548°C, the industrial flue gas supply unit (4) and the micro-nano bubble generator (5) are activated to introduce an industrial flue gas aqueous solution rich in micro-nano bubbles for carbonation reaction. If the infrared thermometer (23) detects a local temperature rise, the zone control mode is automatically triggered to perform local enhanced cooling. The gas concentration sensor (25) provides safety interlock protection throughout the process. (d) Waste heat recovery and drainage: The high-temperature waste gas generated during the treatment process is introduced into the waste heat recovery device (6) through the exhaust port (21) for heat recovery and purification; after the reaction is completed, the control switch valve (13) discharges the leaching water through the drain port (11) and the drainage pipe (12); (e) Safe slag removal: The control unit (7) continuously monitors the state inside the pool and only issues an instruction to open the slag cover (2) after confirming that the temperature of the steel slag is ≤100℃ and the concentration of combustible gas in the pool is close to zero. (f) Remove the cooled slag after processing.

10. The countercurrent submerged hot steel slag treatment coupled with industrial flue gas carbon capture method as described in claim 9, characterized in that: The industrial flue gas introduced in step (c) comes from a steel plant sintering machine or lime kiln, and its carbon dioxide volume concentration ranges from 10% to 30%; the carbon dioxide mass concentration of the industrial flue gas aqueous solution rich in micro-nano bubbles is maintained in the range of 500 mg / L to 1500 mg / L. The heat energy recovered by the waste heat recovery device (6) in step (d) is used to drive the steam turbine generator set, and the generated electrical energy is used to drive the induced draft fan (42) and system water pump in the industrial flue gas supply unit (4); In step (e), if the concentration of combustible gas does not meet the standard, the ventilation and replacement procedure will be automatically started to purge and dilute the pool with inert gas until the concentration is safe before the cover is allowed to be opened. After the steel slag is treated in step (f), with the help of a reasonable secondary magnetic separation process, the metallic iron content in the tailings can be controlled to below 1%, the carbon dioxide capture rate is ≥15%, and the free calcium oxide content is ≤1.5%. The micro-nano bubble generator (5) is not started in step (b), but only in step (c) after the temperature in the pool drops below 548°C.

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