Steel slag waste heat cooling recovery and modification treatment equipment and treatment method

Abstract

The invention discloses steel slag waste heat stepped cooling recovery and modification treatment equipment and method. The steel slag waste heat stepped cooling recovery and modification treatment equipment comprises a first-stage cooling roller, a second-stage modification roller and a third-stage cooling roller which are sequentially arranged from top to bottom; a discharge port of the first-stage cooling roller is communicated with a feed port of the second-stage modification roller through an upper conveying pipe, and a discharge port of the second-stage modification roller is communicated with a feed port of the third-stage cooling roller through a lower conveying pipe; a water circulation cooling recovery system is arranged on the first-stage cooling roller and the third-stage cooling roller, a heat preservation structure is arranged on the second-stage modification roller, and a COO input pipe is mounted on the second-stage modification roller; the temperature of the steel slag discharged from the first-stage cooling roller is adjusted by adjusting the rotating speed of the first-stage cooling roller, so that the temperature of the steel slag discharged into the second-stage modification roller is within the modification temperature range. The waste heat of the steel slag can be recycled in a stepped mode, modification treatment is carried out in the recycling process, secondary heating is not needed in the modification treatment process, and energy utilization is improved.

Description

Technical Field

[0001] This invention relates to a cascade cooling, recovery, and modification treatment device and method for steel slag waste heat, belonging to the technical field of steel slag waste heat cooling, recovery, and modification treatment. Background Technology

[0002] The steel industry generates significant energy consumption and solid waste emissions. Converter slag is a byproduct of steel production, produced at temperatures of 1450-1650℃, and its output accounts for approximately 10wt%-15wt% of crude steel production. Molten steel slag not only possesses enormous calorific value but also has high utilization value. Using it as a building material is a practical and feasible path to achieve large-scale resource utilization of solid waste and environmental protection.

[0003] In the waste heat recovery of high-temperature steel slag, there is a problem that the steel slag, after waste heat recovery, is difficult to reuse as a bulk solid waste. Steel slag contains alkaline oxides such as CaO and MgO. The standard requires that the proportion of CaO and MgO in steel slag can reach more than 45%. The free calcium oxide (f-CaO) and free magnesium oxide (f-MgO) contained in steel slag are the core "hidden danger components". They will slowly react with water at room temperature (f-CaO+H2O→Ca(OH)2, volume expansion of about 98%; f-MgO+H2O→Mg(OH)2, volume expansion of about 148%). If the unstabilized steel slag is directly used in building materials (such as roadbeds and concrete aggregates), it will lead to structural cracking, deformation, and even cause engineering accidents such as road collapse and building wall leakage. After steel slag is modified to reduce the content of free calcium oxide (f-CaO) and magnesium oxide (f-MgO) to meet the requirements of "Technical Specification for Highway Subgrade Construction" JTG / T3610-2019 and "Technical Standard for Steel Slag Application" GB / T20491-2017, it can be used as a filler for subgrade treatment or as an aggregate mixed with asphalt for road construction projects such as pavement laying.

[0004] In the process of modifying steel slag, it is difficult to modify steel slag at room temperature, so it is divided into dry method and wet method. The wet method adds acidic liquid to react, which may pose a risk of environmental pollution due to the presence of acidic liquid. The dry method often needs to be carried out at high temperature due to the reaction rate, which results in high heating cost.

[0005] In dry modification processes, carbon dioxide is generally used for modification. CaO and CO2: Under anhydrous conditions, the initial temperature is approximately 100-150℃. At this point, CO2 begins to adsorb onto the CaO surface and undergo a chemical reaction, but the rate is extremely slow (the product CaCO3 forms a dense film, hindering CO2 diffusion into the interior); MgO and CO2: MgO has a higher lattice energy than CaO (stronger ionic bonds), resulting in lower reactivity. Under anhydrous conditions, the initial temperature is approximately 200-250℃, and there is almost no significant reaction at room temperature (the rate is close to zero). The optimal temperature for CaO and CO2 is 600~700℃ (within this range, surface reaction and internal diffusion are optimally coordinated, the reaction rate is fastest, and the carbonation conversion rate of steel slag can reach 60%~80%); while due to the lower activity of MgO, the optimal temperature is slightly higher, at 700~800℃.

[0006] This modification temperature requires the steel slag to be reheated after waste heat recovery before modification can be carried out. The modification process needs to be carried out at the modification temperature. If the modification is carried out during the waste heat recovery process, a relatively constant temperature is required, but waste heat cannot be recovered during the modification process, resulting in heat loss.

[0007] In conclusion, the existing technology obviously has inconveniences and defects in practical use, so it is necessary to improve it. Summary of the Invention

[0008] To address the shortcomings of the prior art, this invention provides a cascade cooling recovery and modification treatment device and method for steel slag waste heat, which can recover the waste heat of steel slag in stages and perform modification treatment during the recovery process. The modification treatment does not require secondary heating, thus improving energy utilization.

[0009] To solve the above technical problems, the present invention adopts the following technical solution: A waste heat recovery and modification treatment device for steel slag includes a primary cooling drum, a secondary modification drum, and a tertiary cooling drum, which are arranged from top to bottom. The discharge port of the first-stage cooling roller is connected to the inlet of the second-stage modified roller through the upper conveying pipe, and the discharge port of the second-stage modified roller is connected to the inlet of the third-stage cooling roller through the lower conveying pipe. The primary and tertiary cooling drums are equipped with a water circulation cooling and recovery system, the secondary modified drum is equipped with a heat insulation structure, and a CO2 input pipe 206 is installed on the secondary modified drum. By adjusting the rotation speed of the primary cooling drum, the temperature of the steel slag discharged from the primary cooling drum is adjusted, so that the temperature of the steel slag discharged into the secondary modification drum is within the modification temperature range.

[0010] Furthermore, the secondary modified roller is provided in three parts, namely the first modified roller, the second modified roller and the third modified roller, and the discharge end of the upper conveying pipe is provided with three lower branch pipes that are connected one-to-one with the feed inlets of the first modified roller, the second modified roller and the third modified roller. The feed end of the lower feed pipe is provided with three upper branch pipes that are connected one-to-one with the discharge ports of the first modified roller, the second modified roller and the third modified roller.

[0011] Furthermore, a first valve is provided on the lower branch pipe connected to the feed inlet of the first modified roller, a second valve is provided on the lower branch pipe connected to the feed inlet of the second modified roller, and a third valve is provided on the lower branch pipe connected to the feed inlet of the third modified roller; a fourth valve is provided on the upper branch pipe connected to the discharge outlet of the first modified roller, a fifth valve is provided on the upper branch pipe connected to the discharge outlet of the second modified roller, and a sixth valve is provided on the upper branch pipe connected to the discharge outlet of the third modified roller.

[0012] Furthermore, the secondary modified roller includes a fixed sleeve disposed at one end and a rotating drum that rotates relative to the fixed sleeve. The upper end of the fixed sleeve is connected to the lower branch pipe of the upper conveying pipe, and the lower end of the fixed sleeve is connected to the upper branch pipe of the lower conveying pipe.

[0013] Furthermore, the outer side of the secondary modified roller is encapsulated with a sealed insulation box; the inner and outer sides of the secondary modified roller wall are respectively provided with an inner insulation layer and an outer insulation layer, the inner insulation layer is installed on the inner side of the roller wall by fixing nails, and a spiral guide plate is also provided on the inner side of the inner insulation layer.

[0014] Furthermore, multiple lifting plates are provided axially around the inner side of the secondary modified drum wall. The outer ends of the lifting plates are fixed to the drum wall of the secondary modified drum, and the outer ends of the lifting plates extend to the inner side of the inner insulation layer for a certain length.

[0015] Furthermore, the inner end of the secondary modified drum away from the fixed sleeve is provided with wear-resistant and heat-insulating material, which covers the entire inner end face of the drum; The secondary modified roller drum has multiple concentric ring plates of different diameters and multiple radial vertical plates inside one end with wear-resistant and heat-insulating material. The inner ends of the ring plates and vertical plates extend beyond the inner end face of the wear-resistant and heat-insulating material by a certain length, so that the ring plates and vertical plates form multiple fan-shaped grid areas.

[0016] A method for the staged cooling recovery and modification of waste heat from steel slag includes the following steps: Step 1: Open the first valve and close the other valves. After the steel slag is cooled to the modification temperature in the primary cooling drum, it flows into the first modification drum. Open the air inlet valve on the CO2 input pipe 206 on the first modification drum. Step 2: When the first modified drum is installed to its maximum capacity, close the first valve. The steel slag undergoes a modification reaction inside the first modified drum, and CO2 is continuously introduced during the modification process. At the same time, open the second valve and the air inlet valve on the CO2 input pipe 206 on the second modified drum to feed the second modified drum and introduce carbon dioxide. Step 3: When the second modified drum is loaded to its maximum capacity, close the second valve. The steel slag undergoes a modification reaction inside the second modified drum, and CO2 is continuously introduced during the modification process. At the same time, open the third valve and the air inlet valve on the CO2 input pipe 206 on the third modified drum; the third modified drum is then fed.

[0017] Step 4: When the third modification drum is loaded to its maximum capacity, close the third valve. The steel slag will undergo a modification reaction inside the third modification drum, and CO2 will be continuously introduced during the modification process.

[0018] Furthermore, in step three, while opening the third valve, the fourth valve is also opened, so that the steel slag that has been modified in the first modified drum is discharged from the branch pipe on the corresponding lower conveying pipe. In step four, while closing the third valve, the fourth valve is closed, and the first and fifth valves are opened. At this time, the first modified roller starts feeding again, and the second modified roller starts discharging. After the third modified roller finishes feeding, the modification reaction begins. The first modified roller finishes discharging and starts feeding again, while the second modified roller starts discharging. After the steel slag in the third modifying drum has been modified, the sixth valve is opened to discharge the material. At the same time, the first and fifth valves are closed. At this time, the first modifying drum is fed again to carry out the modification reaction, and the second modifying drum starts to feed, so that the three secondary modifying drums feed and discharge material in sequence.

[0019] Furthermore, during the feeding and discharging process of the secondary modified drum, when the secondary modified drum is feeding, the drum rotates in the forward direction, causing the steel slag inside the drum to move away from the fixed sleeve. When the secondary modified drum is discharging, the drum rotates in the reverse direction, causing the steel slag inside the drum to move towards the fixed sleeve.

[0020] Compared with the prior art, the present invention, by adopting the above technical solution, has the following advantages: Waste heat recovery is carried out in stages within the primary and tertiary cooling drums. There is no need to reheat the steel slag for modification reaction. Instead, the steel slag is cooled to an intermediate temperature after exiting the kiln and maintained at that temperature for modification reaction. After the reaction is completed, it is cooled again, which will not affect the heat recovery of the steel slag exiting the kiln. Thus, waste heat recovery can be carried out in stages while steel slag modification can be achieved.

[0021] There are three secondary modification rollers, which allow the first, second and third modification rollers to cycle and alternately perform feeding, modification reaction and discharge, realizing uninterrupted operation of the primary and tertiary cooling rollers without affecting the discharge of the rotary kiln and the cooling of steel slag.

[0022] The upper end of the fixed sleeve is connected to the lower branch pipe of the upper conveying pipe, and the lower end of the fixed sleeve is connected to the upper branch pipe of the lower conveying pipe. The inlet and outlet of the secondary modified roller are both located at the fixed sleeve end. The feeding and discharging are controlled by forward and reverse rotation. It is only necessary to ensure the seal between one end of the rotating drum and the fixed sleeve, while the other end is made wear-resistant, which makes the sealing simpler, more reliable and lower in cost.

[0023] The outer side of the secondary modification drum is enclosed with a sealed heat preservation box. The inner and outer sides of the drum wall are respectively provided with an inner heat preservation layer and an outer heat preservation layer. The inner side of the inner heat preservation layer is also provided with a spiral guide plate and a lifting plate, which achieves a good heat preservation effect and allows the steel slag to be modified at the modification reaction temperature.

[0024] The end of the secondary modified drum equipped with wear-resistant and heat-insulating material has multiple annular plates and vertical plates inside, forming multiple fan-shaped grid areas. The wear-resistant and heat-insulating material itself has a certain wear-resistant and heat-insulating effect. In addition, the vertical plates and annular plates protrude from the surface of the wear-resistant and heat-insulating material, bearing part of the friction force. Moreover, a portion of steel slag accumulates in the grid area formed by the vertical plates and annular plates. This portion of steel slag isolates the direct friction between the rotating steel slag and the wear-resistant and heat-insulating material, ultimately greatly reducing the friction at the closed end of the secondary modified drum.

[0025] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the side connection structure of the present invention; Figure 3 This is a schematic cross-sectional view of the secondary modified roller; Figure 4 This is a schematic diagram of the sealing end of the secondary modified roller; Figure 5 yes Figure 4 Side view.

[0027] In the picture, 1- Primary cooling drum, 2- Secondary modified drum, 201- First modified drum, 202- Second modified drum, 203- Third modified drum, 204- Fixed sleeve, 205- Rotary drum, 206- CO2 input pipe, 3- Tertiary cooling drum, 4- Rotary kiln, 5- Water pipe assembly, 6- First valve, 7- Second valve, 8- Third valve, 9- Fourth valve, 10- Fifth valve, 11- Sixth valve, 12- Upper conveying pipe, 13- Lower conveying pipe, 14- Inner insulation layer, 15- Outer insulation layer, 16- Fixing nail, 17- Spiral guide plate, 18- Lifting plate, 19- Insulation box, 20- Wear-resistant insulation material, 21- Ring plate, 22- Vertical plate. Detailed Implementation

[0028] 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.

[0029] like Figure 1-2 As shown, the present invention provides a steel slag waste heat cascade cooling recovery and modification treatment equipment, including a primary cooling drum 1, a secondary modification drum 2 and a tertiary cooling drum 3, which are arranged in order from top to bottom; The discharge port of the first-stage cooling roller 1 is connected to the inlet of the second-stage modified roller 2 through the upper conveying pipe 12, and the discharge port of the second-stage modified roller 2 is connected to the inlet of the third-stage cooling roller 3 through the lower conveying pipe 13. The primary cooling drum 1 and the tertiary cooling drum 3 are equipped with a water circulation cooling and recovery system, the secondary modified drum 2 is equipped with a heat insulation structure, and the secondary modified drum 2 is equipped with a CO2 input pipe 206. By adjusting the rotational speed of the primary cooling drum 1, the temperature of the steel slag discharged from the primary cooling drum 1 is adjusted, ensuring that the temperature of the steel slag discharged into the secondary modification drum 2 is within the modification temperature range. During the manufacturing process, changing the size and length of the primary cooling drum 1 will also adjust the temperature of the discharged steel slag; in addition, changing the flow rate and cooling speed of the cooling water will also affect the temperature of the discharged steel slag.

[0030] like Figure 2 The secondary modified roller 2 has three parts, namely the first modified roller 201, the second modified roller 202 and the third modified roller 203. The discharge end of the upper conveying pipe 12 has three lower branch pipes that are connected to the inlets of the first modified roller 201, the second modified roller 202 and the third modified roller 203 respectively. The inlet end of the lower conveying pipe 13 has three upper branch pipes that are connected to the outlets of the first modified roller 201, the second modified roller 202 and the third modified roller 203 respectively.

[0031] A first valve 6 is provided on the lower branch pipe connected to the feed inlet of the first modified roller 201; a second valve 7 is provided on the lower branch pipe connected to the feed inlet of the second modified roller 202; and a third valve 8 is provided on the lower branch pipe connected to the feed inlet of the third modified roller 203. A fourth valve 9 is provided on the upper branch pipe connected to the discharge outlet of the first modified roller 201; a fifth valve 10 is provided on the upper branch pipe connected to the discharge outlet of the second modified roller 202; and a sixth valve 11 is provided on the upper branch pipe connected to the discharge outlet of the third modified roller 203.

[0032] Before the equipment starts running, carbon dioxide is introduced into the secondary modification drum 2 through the CO2 input pipe 206 to make its concentration reach more than 96% and the pressure is atmospheric pressure. The equipment starts running and the temperature of the discharged steel slag is adjusted to the modification temperature (adjustable, for example, 700℃) by adjusting the speed of the primary cooling drum. After precise cooling control, the steel slag at the modification temperature enters the secondary modification drum 2 through the upper conveying pipe 12.

[0033] The secondary modified roller 2 includes a fixed sleeve 204 disposed at one end and a rotating drum 205 that rotates relative to the fixed sleeve 204. The upper end of the fixed sleeve 204 is connected to the lower branch pipe of the upper conveying pipe 12, and the lower end of the fixed sleeve 204 is connected to the upper branch pipe of the lower conveying pipe 13.

[0034] When the secondary modified drum 2 is fed, the drum 205 rotates in the forward direction, causing the steel slag inside the drum 205 to move away from the fixed sleeve 204. When the secondary modified drum 2 is discharged, the drum 205 rotates in the reverse direction, causing the steel slag inside the drum 205 to move closer to the fixed sleeve 204. By controlling the forward and reverse rotation of the drum 205, the feeding and discharging of the steel slag are controlled. Since the inlet and outlet of the secondary modified drum 2 are both located at the fixed sleeve 204, it is only necessary to ensure a seal between one end of the drum 205 and the fixed sleeve 204, while ensuring wear resistance at the other end (compared to feeding and discharging from both ends separately, this equipment has a simpler and more reliable sealing method and lower cost).

[0035] The outer side of the secondary modified roller 2 is encapsulated with a sealed heat preservation box 19 for heat preservation; the inner and outer sides of the cylinder wall of the secondary modified roller 2 are respectively provided with an inner heat preservation layer 14 and an outer heat preservation layer 15. The inner heat preservation layer 14 is installed on the inner side of the cylinder wall by fixing nails 16, and a spiral guide plate 17 is also provided on the inner side of the inner heat preservation layer 14.

[0036] Multiple lifting plates 18 are axially arranged around the inner circumference of the inner wall of the secondary modification drum 2 rotating drum 205. The outer ends of the lifting plates 18 are fixed to the drum wall of the secondary modification drum 2 rotating drum 205, and extend a certain length into the inner side of the inner insulation layer 14; furthermore, the outer ends of the lifting plates 18 extend a certain length into the inner side of the spiral guide plate 17. The lifting plates 18 lift the material, increasing the effective reaction area, so that the material can be reacted more fully in the same amount of time. The steel slag rotates and tumbles in the rotating drum 205, increasing the contact area between the steel slag and the reactant gas, expanding the reactant base, increasing the overall reaction volume, and thus increasing the reaction efficiency.

[0037] The outer insulation layer 15 is made of fiber felt or refractory insulation cotton; the inner insulation layer 14 is made of modular castable or refractory insulation brick, which plays the role of heat insulation and wear resistance, reduces heat loss, and allows the steel slag to react at the modification temperature during the modification process, while protecting the cylinder wall of the secondary modification roller 205 from being worn.

[0038] The inner end of the secondary modified roller 205 away from the fixed sleeve 204 is provided with wear-resistant and heat-insulating material 20, which covers the entire inner end face of the roller 205.

[0039] The secondary modified roller 2, rotating drum 205, has multiple concentric ring plates 21 of different diameters and multiple radially arranged vertical plates 22 inside one end of the wear-resistant and heat-insulating material 20. The inner ends of the ring plates 21 and vertical plates 22 extend beyond the inner end face of the wear-resistant and heat-insulating material 20 by a certain length, so that the ring plates 21 and vertical plates 22 form multiple fan-shaped grid areas, such as... Figure 4 and Figure 5 As shown.

[0040] During the modification reaction, the end of the secondary modification drum 205 away from the fixed sleeve 204 is completely closed. When feeding, the material gathers and accumulates in the closed section, and the tumbling friction is more frequent and intense than in other positions. Therefore, the high wear resistance requirement of the closed end necessitates the addition of a reinforced wear-resistant structure inside the closed end to meet the wear resistance requirements. First, the wear-resistant insulation material 20 itself has a certain wear-resistant and heat-insulating effect. In addition, the vertical plate 22 and the ring plate 21 protrude from the surface of the wear-resistant insulation material 20, bearing part of the friction force. Moreover, a portion of steel slag accumulates in the grid area enclosed by the vertical plate 22 and the ring plate 21. This portion of steel slag isolates the direct friction between the rotating steel slag and the wear-resistant insulation material 20, ultimately greatly reducing the friction at the closed end of the secondary modification drum 205.

[0041] The water circulation cooling and recovery system on the primary cooling drum 1 and the tertiary cooling drum 3 includes a circulating water jacket installed on the drum wall, which is connected to the water pipe assembly 5.

[0042] Based on the aforementioned equipment for cooling, recovering, and modifying waste heat from steel slag, this invention also proposes a method for cooling, recovering, and modifying waste heat from steel slag, comprising the following steps: Step 1: Open the first valve 6 and close the remaining valves. After the steel slag is cooled to the modification temperature in the primary cooling drum 1, it flows into the first modification drum 201. Open the inlet valve on the CO2 input pipe 206 on the first modification drum 201. Introduce the modified gas CO2 into the first modification drum 201.

[0043] Step 2: When the first modified roller 201 is installed to its maximum capacity (generally 45%-55% of the total internal capacity of the shell), close the first valve 6. The steel slag undergoes a modification reaction inside the first modified roller 201, and CO2 is continuously introduced during the modification process to replenish the portion absorbed by the modification reaction or the portion accidentally lost, maintaining the CO2 concentration. Depending on the equipment's sealing and pressure rating and the reaction rate, it can be appropriately adjusted to a positive pressure state to improve the reaction rate. At the same time, open the second valve 7 and the air inlet valve on the CO2 input pipe 206 on the second modified roller 202 to allow the second modified roller 202 to be fed and carbon dioxide to be introduced.

[0044] Step 3: When the second modified roller 202 is loaded to its maximum capacity, close the second valve 7. The steel slag undergoes a modification reaction in the second modified roller 202, and CO2 is continuously introduced during the modification process. At the same time, open the third valve 8 and the air inlet valve on the CO2 input pipe 206 on the third modified roller 203, and feed material into the third modified roller 203.

[0045] Step 4: When the third modification drum 203 is loaded to its maximum capacity, close the third valve 8. The steel slag will undergo a modification reaction inside the third modification drum 203, and CO2 will be continuously introduced during the modification process.

[0046] In step three, while opening the third valve 8, the fourth valve 9 is also opened, allowing the steel slag that has been modified in the first modified roller 201 to be discharged from the branch pipe on its corresponding lower conveyor pipe 13. When the third modified roller 203 is feeding, the first modified roller 201 has completed its modification and is discharged.

[0047] In step four, while closing the third valve 8, the fourth valve 9 is closed, and the first valve 6 and the fifth valve 10 are opened. At this time, the first modified roller 201 starts feeding again, and the second modified roller 202 starts discharging. After the third modified roller 203 finishes feeding, the modification reaction begins. The first modified roller 201 finishes discharging and starts feeding again, while the second modified roller 202 starts discharging.

[0048] After the steel slag in the third modifying roller 203 has been modified, the sixth valve 11 is opened to discharge the material. At the same time, the first valve 6 and the fifth valve 10 are closed. At this time, the first modifying roller 201 is fed again to carry out the modification reaction, and the second modifying roller 202 starts to feed. In this way, the three secondary modifying rollers 2 feed and discharge material in sequence, so that the first-stage cooling roller 1 discharges material continuously and the tertiary cooling roller 3 cools continuously.

[0049] During the feeding and discharging process of the secondary modified drum 2, when the secondary modified drum 2 is feeding, the drum 205 rotates in the forward direction, causing the steel slag inside the drum 205 to move away from the fixed sleeve 204. When the secondary modified drum 2 is discharging, the drum 205 rotates in the reverse direction, causing the steel slag inside the drum 205 to move closer to the fixed sleeve 204. By controlling the forward and reverse rotation of the drum 205, the feeding and discharging of the steel slag are controlled.

[0050] In the above-mentioned method for waste heat cooling recovery and modification treatment of steel slag, since feeding and discharging are not allowed during the modification reaction time, if only one secondary modification roller 2 is set up, it will not be able to meet the uninterrupted operation of the primary cooling roller 1 and the tertiary cooling roller 3. The first modification roller 201, the second modification roller 202 and the third modification roller 203 are fed, modified and discharged in sequence, achieving uninterrupted operation of the primary cooling roller 1 and the tertiary cooling roller 3 without affecting the discharge of the rotary kiln 4 and the cooling of the steel slag.

[0051] Specifically, the modification reaction time is generally 1.5-3 hours (it will vary depending on the amount and composition of the steel slag). By controlling the feeding and discharging time of the secondary modification roller 2 to be equal to the modification reaction time, the first modification roller 201, the second modification roller 202 and the third modification roller 203 can continuously carry out feeding, modification reaction and discharging, achieving uninterrupted operation.

[0052] The specific working principle of this invention: The steel slag discharged from the rotary kiln 4 is directly discharged into the primary cooling drum 1 for cooling. By adjusting the rotation speed of the primary cooling drum 1, the temperature of the steel slag discharged from the primary cooling drum 1 to the secondary modification drum 2 can be adjusted, so that the temperature of the steel slag drops from 1300℃ to the modification temperature (around 700℃), and the first stage of waste heat recovery is carried out in the primary cooling drum 1.

[0053] After steel slag is injected into the secondary modification drum 2, the sealed end of the secondary modification drum 2 is equipped with wear-resistant and heat-insulating material 20, and the other end is equipped with a fixed sleeve 204. The drum 205 feeds material when rotating in the forward direction and discharges material when rotating in the reverse direction (both the inlet and outlet are located on the fixed sleeve 204). The secondary modification drum 2 is equipped with a heat-insulating structure to prevent temperature fluctuations during the modification reaction. In fact, the modification reaction is an exothermic reaction, which reduces the heat-insulating requirements and ensures that the temperature is maintained within the appropriate range during the modification reaction.

[0054] After the modification reaction is complete, the slag is discharged into the third-stage cooling drum 3, where the second stage of waste heat recovery takes place. Throughout the process, waste heat recovery is carried out in stages within the first-stage cooling drum 1 and the third-stage cooling drum 3. There is no need for secondary heating of the steel slag for the modification reaction; instead, a certain intermediate temperature (modification temperature) is utilized after the steel slag exits the kiln and maintained at this temperature for the modification reaction. Subsequent cooling after the reaction is complete does not affect the heat recovery of the steel slag exiting the kiln, thus achieving staged waste heat recovery while still enabling steel slag modification.

[0055] 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 cascade cooling, recovery, and modification treatment device for waste heat from steel slag, characterized in that: It includes a primary cooling roller (1), a secondary modification roller (2), and a tertiary cooling roller (3), which are arranged from top to bottom. The discharge port of the first-stage cooling roller (1) is connected to the inlet of the second-stage modified roller (2) through the upper conveying pipe (12), and the discharge port of the second-stage modified roller (2) is connected to the inlet of the third-stage cooling roller (3) through the lower conveying pipe (13). The primary cooling drum (1) and the tertiary cooling drum (3) are equipped with a water circulation cooling and recovery system, the secondary modified drum (2) is equipped with a heat insulation structure, and the secondary modified drum (2) is equipped with a CO2 input pipe 206. By adjusting the rotation speed of the primary cooling drum (1), the temperature of the steel slag discharged from the primary cooling drum (1) is adjusted so that the temperature of the steel slag discharged into the secondary modification drum (2) is within the modification temperature range.

2. The waste heat recovery and modification equipment for steel slag as described in claim 1, characterized in that: The secondary modified roller (2) is provided in three parts, namely the first modified roller (201), the second modified roller (202) and the third modified roller (203). The discharge end of the upper conveying pipe (12) is provided with three lower branch pipes that are connected one-to-one with the feed inlets of the first modified roller (201), the second modified roller (202) and the third modified roller (203). The feed end of the lower feed pipe (13) is provided with three upper branch pipes that are connected one-to-one with the discharge ports of the first modified roller (201), the second modified roller (202) and the third modified roller (203).

3. The waste heat recovery and modification equipment for steel slag as described in claim 2, characterized in that: A first valve (6) is provided on the lower branch pipe connected to the feed port of the first modified roller (201), a second valve (7) is provided on the lower branch pipe connected to the feed port of the second modified roller (202), and a third valve (8) is provided on the lower branch pipe connected to the feed port of the third modified roller (203); a fourth valve (9) is provided on the upper branch pipe connected to the discharge port of the first modified roller (201), a fifth valve (10) is provided on the upper branch pipe connected to the discharge port of the second modified roller (202), and a sixth valve (11) is provided on the upper branch pipe connected to the discharge port of the third modified roller (203).

4. The waste heat recovery and modification equipment for steel slag as described in claim 3, characterized in that: The secondary modified roller (2) includes a fixed sleeve (204) disposed at one end and a rotating drum (205) rotating relative to the fixed sleeve (204). The upper end of the fixed sleeve (204) is connected to the lower branch pipe of the upper conveying pipe (12), and the lower end of the fixed sleeve (204) is connected to the upper branch pipe of the lower conveying pipe (13).

5. The waste heat recovery and modification equipment for steel slag as described in claim 4, characterized in that: The outer side of the secondary modified roller (2) is encapsulated with a sealed heat preservation box (19); The inner and outer sides of the secondary modified roller (2) are respectively provided with an inner insulation layer (14) and an outer insulation layer (15). The inner insulation layer (14) is installed on the inner side of the roller wall by fixing nails (16), and a spiral guide plate (17) is also provided on the inner side of the inner insulation layer (14).

6. The waste heat recovery and modification equipment for steel slag as described in claim 4, characterized in that: Multiple lifting plates (18) are provided along the axial direction on the inner side of the inner wall of the secondary modified drum (2) (205). The outer ends of the lifting plates (18) are fixed on the inner wall of the secondary modified drum (2) (205), and the outer ends of the lifting plates (18) extend to the inner side of the inner insulation layer (14) for a certain length.

7. The waste heat recovery and modification equipment for steel slag as described in claim 6, characterized in that: The inner end of the secondary modified roller (2) (205) away from the fixed sleeve (204) is provided with wear-resistant and heat-insulating material (20), and the wear-resistant and heat-insulating material (20) covers the entire inner end face of the roller (205); The secondary modified roller (2) has a plurality of concentric ring plates (21) of different diameters and a plurality of radial vertical plates (22) inside one end of the roller (2) with wear-resistant and heat-insulating material (20). The inner ends of the ring plates (21) and the vertical plates (22) extend beyond the inner end face of the wear-resistant and heat-insulating material (20) by a certain length, so that the ring plates (21) and the vertical plates (22) form a plurality of fan-shaped grid areas.

8. A method for the staged cooling, recovery, and modification of waste heat from steel slag, characterized in that: The modification treatment method, based on the steel slag waste heat cascade cooling recovery and modification treatment equipment according to any one of claims 4-7, includes the following steps: Step 1: Open the first valve (6) and close the other valves. After the steel slag is cooled to the modification temperature in the first-stage cooling drum (1), it flows into the first modification drum (201) and the air inlet valve on the CO2 input pipe 206 on the first modification drum (201) is opened. Step 2: When the first modified roller (201) is loaded to its maximum capacity, close the first valve (6). The steel slag undergoes a modification reaction in the first modified roller (201), and CO2 is continuously introduced during the modification process. At the same time, open the second valve (7) and the air inlet valve on the CO2 input pipe 206 on the second modified roller (202) to feed the second modified roller (202) and introduce carbon dioxide. Step 3: When the second modified drum (202) is loaded to its maximum capacity, close the second valve (7). The steel slag undergoes a modification reaction in the second modified drum (202), and CO2 is continuously introduced during the modification process. At the same time, open the third valve (8) and the air inlet valve on the CO2 input pipe 206 on the third modified drum (203), and feed into the third modified drum (203). Step 4: When the third modification drum (203) is loaded to its maximum capacity, close the third valve (8). The steel slag third modification drum (203) undergoes a modification reaction, and CO2 is continuously introduced during the modification process.

9. The method for staged cooling recovery and modification of steel slag waste heat as described in claim 8, characterized in that: In step three, while opening the third valve (8), the fourth valve (9) is opened, so that the steel slag that has been modified in the first modified roller (201) is discharged from the branch pipe on the corresponding lower conveying pipe (13); In step four, while closing the third valve (8), the fourth valve (9) is closed, and the first valve (6) and the fifth valve (10) are opened. At this time, the first modified roller (201) starts feeding again, and the second modified roller (202) starts discharging. At this time, the third modified roller (203) completes the feeding and carries out the modification reaction. The first modified roller (201) finishes discharging and starts feeding again, while the second modified roller (202) starts discharging. After the steel slag in the third modified roller (203) has been modified, the sixth valve (11) is opened to discharge the material. At the same time, the first valve (6) and the fifth valve (10) are closed. At this time, the first modified roller (201) feeds in again to carry out the modification reaction, and the second modified roller (202) starts to feed in, so that the three secondary modified rollers (2) feed and discharge in sequence.

10. The method for graded cooling recovery and modification of steel slag waste heat as described in claim 9, characterized in that: During the feeding and discharging process of the secondary modified drum (2), when the secondary modified drum (2) is fed, the drum (205) rotates in the forward direction, causing the steel slag in the drum (205) to move away from the fixed sleeve (204). When the secondary modified drum (2) is discharged, the drum (205) rotates in the reverse direction, causing the steel slag in the drum (205) to move towards the fixed sleeve (204).

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