Device and method for carbon sequestration of steel slag

Abstract

The present application relates to the field of resource utilization of industrial waste, and specifically relates to a device and method for carbon sequestration of steel slag. The device for carbon sequestration of steel slag comprises a device body, and a sprayer and a vent, which are arranged at the top of the structure of the device body, wherein the device body is further provided with a feeding port, a discharging port and an air intake port, a conveying unit is arranged in the device body, and the conveying unit comprises a plurality of conveying mechanisms. The device can introduce industrial waste gas containing carbon dioxide into steel slag under the condition that the ambient humidity is maintained at 80-100%, thereby achieving carbon sequestration of the steel slag. In the present application, by controlling the ambient humidity, maintaining the moisture content of the steel slag during the process of a reaction of same with carbon dioxide and reducing the contact time of water and the steel slag at the same time, calcium in the steel slag is prevented from being dissolved out, and a water film is not formed on the surface of the steel slag to affect the reaction of carbon dioxide with free calcium oxide in the steel slag, thereby enabling a further reaction between carbon dioxide and free calcium oxide.

Description

Device and method for carbon fixation in steel slag

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on July 24, 2023, with application number 202310911825.8 and invention name “A device and method for carbon fixation in steel slag”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of resource utilization of industrial waste, and specifically to a device and method for carbon fixation of steel slag. Background Art

[0004] Steel slag is one of the main by-products of the steel production process. A large amount of steel slag is produced every year, but 60% of it has not been effectively utilized. Therefore, the resource utilization of steel slag is of great significance. The main reason limiting the resource utilization of steel slag is that it contains a large amount of unstable free calcium oxide. On the one hand, the high free calcium oxide content in steel slag makes the steel slag prone to expansion and pulverization, and poor volume stability, which in turn leads to a series of quality problems such as pavement expansion and cracking when the steel slag is used in road projects. On the other hand, the reduction effect of free calcium oxide in steel slag is unstable and difficult to maintain at a low level. At present, the main method is to use carbon dioxide to react with the free calcium oxide in steel slag to form calcium carbonate. This can effectively improve the stability of steel slag and expand the scope of steel slag utilization, while also reducing carbon dioxide emissions. It has the dual benefits of carbon dioxide emission reduction and solid waste resource recovery.

[0005] The prior art discloses a method for fixing CO2 and digesting free calcium oxide in steel slag micropowder, which mainly involves allowing the soaked steel slag to react stably with waste heat flue gas containing carbon dioxide in a grinding mill to achieve carbon dioxide fixation and digestion of free calcium oxide. However, this method causes excess water to remain on the surface of the steel slag due to soaking, forming a water film, which affects the contact between carbon dioxide and free calcium oxide in the steel slag. At the same time, soaking the steel slag causes other calcium elements besides free calcium oxide to dissolve. The wastewater after soaking the steel slag needs to be treated again, increasing resource utilization costs. At the same time, the loss of calcium elements causes a decrease in the carbon fixation rate of the steel slag.

[0006] Summary of the Invention

[0007] Therefore, the technical problem to be solved by this application is to overcome the defects of the prior art in which steel slag is soaked to form a water film, which affects the contact between carbon dioxide and free calcium oxide in the steel slag, increases the cost of wastewater reprocessing, and causes the loss of calcium elements in the steel slag, resulting in a low carbon fixation rate of the steel slag, thereby providing a steel slag carbon fixation device and method to improve the steel slag carbon fixation rate.

[0008] On the one hand, the present application provides a device for carbon fixation of steel slag, including a device body, a sprinkler and an exhaust port arranged on the top of the device body structure. The device body is also provided with a feed port, a discharge port and an air inlet. The position of the feed port is higher than the position of the discharge port, and the air inlet is located between the feed port and the discharge port. A conveying unit is provided inside the device body, and the conveying unit includes several conveying mechanisms.

[0009] On the other hand, the present application provides a method for carbon fixation in steel slag, comprising the following steps: introducing industrial waste gas containing carbon dioxide into the steel slag under an ambient humidity of 80-100%.

[0010] The industrial waste gas containing carbon dioxide also contains SO2; optionally, the volume content of SO2 is 100-300 ppm.

[0011] The ambient humidity is controlled by the spraying amount of the spraying water.

[0012] The amount of industrial waste gas introduced is 150,000-230,000 m 3 The feed rate of the steel slag is 1-1.5 t / h.

[0013] The volume content of CO2 in the industrial waste gas containing carbon dioxide is ≥10%, and optionally, the volume content of CO2 is ≥25%; the temperature of the industrial waste gas is 100-200°C.

[0014] During the reaction between the steel slag and the industrial waste gas containing carbon dioxide, the pressure is 1-1.5 atm.

[0015] The contact time between the steel slag and the industrial waste gas containing carbon dioxide is 0.5-2 hours; the conveying rate of the steel slag is 0.5-1.5 m / min.

[0016] More than 50% of the particles in the steel slag have a diameter of ≤80 μm; before feeding, the moisture content of the steel slag is 5-15%; and the water is at least one of industrial wastewater and reclaimed water.

[0017] The steel slag produced by the steel slag carbon fixation device provided in this application or the steel slag produced by the steel slag carbon fixation method provided in this application can be used in building materials or road construction materials.

[0018] The technical solution of this application has the following advantages:

[0019] 1. The present application provides a device for carbonizing steel slag, comprising a device body, a sprayer and an exhaust port arranged at the top of the device body structure, the device body is further provided with a feed port, a discharge port and an air inlet, the feed port is located higher than the discharge port, the air inlet is located between the feed port and the discharge port, a conveying unit is arranged inside the device body, and the conveying unit includes several conveying mechanisms. The present application arranges the sprayer at the top of the device body to facilitate spraying water into the device so that the environmental humidity inside the device meets the requirements. At the same time, the air inlet is arranged between the feed port and the discharge port, which is conducive to sufficient contact between the industrial waste gas and the steel slag fed into the feed port, and avoids the industrial waste gas injected into the device from overflowing from the air outlet without reacting with the steel slag. Furthermore, the present application arranges a conveying unit formed by several conveying mechanisms, which can ensure the reaction time of the steel slag and the industrial waste gas in the device by controlling the conveying rate of each conveying mechanism.

[0020] 2. The present invention provides a method for carbon fixation in steel slag, comprising introducing industrial waste gas containing carbon dioxide into the steel slag under conditions of an ambient humidity of 80-100%. By controlling the ambient humidity, the present invention maintains the moisture content of the steel slag during the reaction with carbon dioxide, reduces the amount of water in contact with the steel slag, and prevents the dissolution of calcium from the steel slag. This allows for a sufficient carbon fixation reaction in the steel slag while preventing the formation of a water film on the steel slag surface that would affect the reaction between the carbon dioxide and the free calcium oxide in the steel slag. Maintaining the ambient humidity allows the reaction between the carbon dioxide and the free calcium oxide in the steel slag to proceed further.

[0021] 3. The method for carbon fixation in steel slag provided in the present application contains sulfur dioxide in addition to carbon dioxide in the industrial waste gas that reacts with the free calcium oxide in the steel slag. The present application introduces industrial waste gas containing sulfur dioxide and carbon dioxide to react with the steel slag. Due to the addition of sulfur dioxide, the generated sulfurous acid and sulfuric acid can react with the compounds on the surface of the steel slag to dissolve gaps, thereby allowing the carbon dioxide to further penetrate into the steel slag and react with the free calcium oxide inside the steel slag, thereby improving the carbon fixation efficiency.

[0022] 4. The method for steel slag carbon fixation provided in the present application sprays water droplets during the steel slag carbon fixation process, while controlling the steel slag conveying rate to 0.5-1.5m / min and the contact time between the steel slag and the industrial waste gas to 0.5-2h, so that the steel slag can fully contact with the sprayed water droplets, ensuring that the moisture content of the steel slag reacting with the industrial waste gas containing carbon dioxide meets the standard, thereby accelerating the reaction efficiency of steel slag carbon fixation.

[0023] 5. The method for carbonizing steel slag provided in this application has a low free calcium oxide content in the steel slag after carbonization, and can be used in building materials or road construction materials. The carbonization process is simple and can effectively absorb industrial waste gas and industrial recycled water. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] FIG1 is a schematic diagram of the structure of the device for carbon fixation of steel slag of the present application;

[0026] Reference numerals: 1 - discharge port, 2 - air inlet, 3 - feed port, 4 - sprayer, 5 - exhaust port, 6 - device body, 7 - conveying unit. DETAILED DESCRIPTION

[0027] The following examples are provided to further better understand the present application, but are not limited to the best implementation mode described herein, and do not limit the content and protection scope of the present application. Any product identical or similar to the present application obtained by anyone under the inspiration of the present application or by combining the features of the present application with other prior arts shall fall within the scope of protection of the present application.

[0028] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0029] The present application provides a steel slag carbon fixation device, as shown in Figure 1, the steel slag carbon fixation device includes a device body 6, a sprayer 4 and an exhaust port 5 arranged on the top of the device body 6 structure, the device body 6 is also provided with a feed port 3, a discharge port 1 and an air inlet 2, the feed port 3 is located higher than the discharge port 1, and the air inlet 2 is located between the feed port 3 and the discharge port 1, a conveying unit 7 is provided inside the device body 6, and the conveying unit 7 includes several conveying mechanisms. In use, steel slag with a moisture content that meets the requirements is put into the conveying mechanism through the feed port 3, the placement angle of the conveying mechanism can be adjusted arbitrarily to ensure that the steel slag can be spread as thinly as possible on the conveying mechanism, and the conveying mechanism drives the steel slag to be conveyed. During the conveying process, industrial waste gas containing carbon dioxide or carbon dioxide and sulfur dioxide is introduced from the air inlet 2, and reclaimed water or industrial waste water is sprayed from the sprayer 4 to maintain the environmental humidity in the device body 6, and the steel slag that has completed carbon fixation is sent out through the discharge port 1.

[0030] Specifically, the feeding method of the present application can adopt spiral feeding, conveying feeding or vibration feeding, etc., preferably the vibration feeding method. By maintaining a certain vibration frequency, the steel slag can be spread more evenly on the conveying unit 7.

[0031] Specifically, the discharging method of the present application can adopt spiral discharging, conveying discharging or vibration discharging, and is preferably vibration discharging, which is more conducive to the discharging of steel slag and avoids excessive humidity and adhesion of steel slag to the discharge port 1.

[0032] Specifically, the present application does not limit the type, material, number and setting position of the conveying mechanism of the conveying unit 7, as long as it can meet the needs of conveying steel slag. The angle formed by each conveying mechanism and the horizontal line is set as the inclination angle of the conveying mechanism. The inclination angle of the conveying mechanism can be adjusted arbitrarily to ensure that the steel slag can be spread as thinly as possible on the conveying mechanism. The conveying mechanism of the present application can be a conveyor belt, and each conveyor belt is provided with a protrusion on the belt to increase the friction between the belt and the steel slag. Each conveyor belt is set at a certain inclination angle to allow the steel slag on the previous conveyor belt to fall onto the next conveyor belt under the action of gravity. The present application provides an optional embodiment, wherein the conveying mechanism is two conveyor belts, wherein one end of the first conveyor belt is provided at the feed port for receiving the steel slag from the feed port 3, the other end of the first conveyor belt is provided above one end of the second conveyor belt, and the second conveyor belt is used to receive the steel slag on the first conveyor belt and convey the steel slag to the discharge port 1. By providing two conveyor belts, the steel slag can be better spread, so that the steel slag is fully in contact with the industrial waste gas.

[0033] Specifically, the present application does not limit the type, location and number of the sprinkler 4, as long as it can maintain the humidity of the environment inside the device at 80-100%. Optionally, the sprinkler 4 is a plurality of droplet sprinklers, which are evenly arranged on the top of the device to ensure uniform humidity of the environment inside the device.

[0034] The steel slags of the examples and comparative examples of the present application had an initial free calcium oxide content of 8%, a chlorine content of 0.015%, and a sulfur content of 0.07% before carbon fixation.

[0035] Example 1

[0036] This embodiment provides a method for carbonizing steel slag, and the specific steps and methods are as follows:

[0037] 1. Before feeding, control the steel slag with a particle size of ≤80μm to account for 50% of the steel slag, and ensure that the moisture content of the steel slag is 10% before feeding. The moisture content of the steel slag is controlled by spraying water on the steel slag.

[0038] 2. The feed rate of steel slag is 1t / h, and the inclination angle of the conveying mechanism is controlled at 15°.

[0039] 3. The device is continuously sprayed with water droplets to maintain the humidity in the device at 80%. At the same time, industrial waste gas containing CO2 is blown in. The volume proportion of CO2 in the CO2-containing industrial waste gas is ≥25%. The injection volume of industrial waste gas is 150,000 m3 3 / h, the temperature of industrial waste gas is 150℃, and the pressure of the device body is 1.5atm.

[0040] 4. Control the conveying mechanism’s conveying rate to 1m / min, so that the slag runs in the device for 1h, that is, the contact time between the slag and the industrial waste gas in the main body of the device is 1h.

[0041] Example 2

[0042] This embodiment provides a method for carbonizing steel slag, and the specific steps and methods are as follows:

[0043] 1. Before feeding, control the steel slag with a particle size of ≤80μm to account for 70% and ensure that the moisture content of the steel slag is 5% before feeding. The moisture content of the steel slag is controlled by spraying water on the steel slag.

[0044] 2. The feed rate of steel slag is 1.5t / h, and the inclination angle of the conveying mechanism is controlled at 25°.

[0045] 3. Industrial wastewater droplets are continuously sprayed into the device to maintain the humidity in the device at 100%. At the same time, industrial waste gas containing CO2 is blown in. The volume proportion of CO2 in the CO2-containing industrial waste gas is ≥30%. The injection volume of industrial waste gas is 200,000 m 3 / h, the temperature of industrial waste gas is 200℃, and the pressure of the device body is 1atm.

[0046] 4. Control the conveying rate of the conveying mechanism to 1.5m / min, so that the steel slag runs in the device for 2 hours, that is, the contact time between the steel slag and the industrial waste gas in the main body of the device is 2 hours.

[0047] Example 3

[0048] This embodiment provides a method for carbonizing steel slag, and the specific steps and methods are as follows:

[0049] 1. Before feeding, control the steel slag with a particle size of ≤80μm to account for 50% of the steel slag, and ensure that the moisture content of the steel slag is 10% before feeding. The moisture content of the steel slag is controlled by spraying water on the steel slag.

[0050] 2. The feed rate of steel slag is 1t / h, and the inclination angle of the conveying mechanism is controlled at 15°.

[0051] 3. The device is continuously sprayed with water droplets to maintain the humidity at 80%. At the same time, industrial waste gas containing CO2 is blown in. The volume content of CO2 in the CO2-containing industrial waste gas is ≥25%, and the volume content of SO2 is 150ppm. The injection volume of industrial waste gas is 150,000 m 3 / h, the temperature of industrial waste gas is 150℃, and the pressure of the device body is 1.5atm.

[0052] 4. Control the conveying mechanism’s conveying rate to 1m / min, so that the slag runs in the device for 1h, that is, the contact time between the slag and the industrial waste gas in the main body of the device is 1h.

[0053] Example 4

[0054] This embodiment provides a method for carbonizing steel slag, and the specific steps and methods are as follows:

[0055] 1. Before feeding, control the proportion of steel slag with particle size ≤80μm to 50%, and ensure that the moisture content of steel slag is 15% before feeding. The moisture content of steel slag is controlled by spraying water on the steel slag.

[0056] 2. The feed rate of steel slag is 1.2t / h, and the inclination angle of the conveying mechanism is controlled at 15°.

[0057] 3. Industrial wastewater droplets are continuously sprayed into the device to maintain the humidity in the device at 90%. At the same time, industrial waste gas containing CO2 is blown in. The volume proportion of CO2 in the CO2-containing industrial waste gas is ≥10%, and the volume content of SO2 is 250ppm. The injection volume of industrial waste gas is 230,000m 3 / h, the temperature of industrial waste gas is 100℃, and the pressure of the device body is 1.2atm.

[0058] 4. Control the conveying rate of the conveying mechanism to 0.5m / min, so that the steel slag runs in the device for 0.5h, that is, the contact time between the steel slag and the industrial waste gas in the main body of the device is 0.5h.

[0059] Example 5

[0060] This embodiment provides a method for carbon fixation in steel slag. The specific steps and methods are the same as those in Example 3, except that the volume content of SO2 in the industrial waste gas is 300 ppm.

[0061] Example 6

[0062] This embodiment provides a method for carbon fixation in steel slag. The specific steps and methods are the same as those in Example 1, except that the moisture content of the feed steel slag is controlled by soaking.

[0063] Example 7

[0064] This embodiment provides a method for carbonizing steel slag. The specific steps and methods are as follows:

[0065] Before feeding, the steel slag is controlled to have a particle size of ≤80μm and account for 70% of the steel slag, and the water content of the steel slag is guaranteed to be fed under 5%. The water content of the steel slag is controlled by spraying water on the steel slag. The structure shown in Figure 1 is adopted. According to the steel slag feeding rate of 1t / h, the steel slag with a moisture content that meets the standard is conveyed to the conveying mechanism through the feeding port 3. The conveying mechanism consists of two conveyor belts. The inclination angles of the two conveyor belts are controlled at 25°, so that the steel slag at the discharge port 1 can be evenly spread on the conveyor belts. At the same time, under the action of gravity, the steel slag on the upper conveyor belt can fall onto the next conveyor belt, and the steel slag is conveyed in the device body 6. At the same time, the sprayer 4 continuously sprays water droplets into the device body 6 to keep the humidity in the device body 6 at 100%. At the same time, the air inlet 2 blows CO2-containing industrial waste gas into the device body 6. The proportion of CO2 in the CO2-containing industrial waste gas is ≥15%, and the injection amount of industrial waste gas is 150,000 m 3 / h; control the conveying rate of each conveyor belt to 1.5m / min, so that the slag runs in the device body 6 for 2h, and the carbon-fixed slag is output through the discharge port 1.

[0066] Comparative Example 1

[0067] The comparative example of the present application provides a method for carbon fixation of steel slag, and the specific steps and methods are the same as those of Example 1, except that the ambient humidity in the steel slag carbon fixation device is maintained at 60%.

[0068] Comparative Example 2

[0069] The comparative example of the present application provides a method for carbon fixation of steel slag, and the specific steps and methods are the same as those of Example 1, except that no spraying is performed during the carbon fixation of steel slag.

[0070] Experimental example

[0071] The free calcium oxide content, chlorine content, and sulfur content of the steel slag treated by the steel slag carbon fixation method in Examples 1-5 and Comparative Examples 1-2 were tested using the YB / T140-2009 "Chemical Analysis Methods for Steel Slag". The test results are shown in Table 1.

[0072] Table 1 Test results of steel slag treated by the steel slag carbon fixation method in Examples 1-5 and Comparative Examples 1-2

[0073] It can be seen that the free calcium oxide, chlorine content and sulfur content of the steel slag treated by the steel slag carbon fixation method in Examples 1-5 of the present application all meet the requirements of the national standard GB / T20491-2017 for the chemical composition of steel slag powder. Moreover, since the free calcium oxide content of the steel slag produced by this method is far less than the prescribed standard, the steel slag produced by this method also has broader application potential.

[0074] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A device for carbon fixation in steel slag, characterized in that: The invention comprises a device body (6), a sprayer (4) and an exhaust port (5) arranged on the top of the device body (6) structure; the device body (6) is also provided with a feed port (3), a discharge port (1) and an air inlet (2); the position of the feed port (3) is higher than the position of the discharge port (1); the air inlet (2) is located between the feed port (3) and the discharge port (1); a conveying unit (7) is arranged inside the device body (6); and the conveying unit (7) includes a plurality of conveying mechanisms.

2. A method for carbon fixation in steel slag, characterized in that: The following steps are included: Under the condition of environmental humidity of 80-100%, industrial waste gas containing carbon dioxide is introduced into the steel slag.

3. The method for carbon fixation in steel slag according to claim 2, characterized in that: The industrial waste gas containing carbon dioxide also contains SO2. Optionally, the volume content of SO2 is 100-300 ppm.

4. The method for carbon fixation in steel slag according to claim 3, characterized in that: The environmental humidity is controlled by the spraying amount of the spraying water.

5. The method for carbon fixation in steel slag according to claim 4, characterized in that: The amount of industrial waste gas introduced is 150,000-230,000 m 3 / h; and / or, The feed rate of the steel slag is 1-1.5 t / h.

6. The method for carbon fixation in steel slag according to claim 5, characterized in that: The volume content of CO2 in the industrial waste gas containing carbon dioxide is ≥10%, and optionally, the volume content of CO2 is ≥25%; And / or, the temperature of the industrial waste gas is 100-200°C.

7. The method for carbon fixation in steel slag according to claim 6, characterized in that: During the reaction between the steel slag and the industrial waste gas containing carbon dioxide, the pressure is 1-1.5 atm.

8. The method for carbon fixation in steel slag according to any one of claims 2 to 7, characterized in that: The contact time between the steel slag and the industrial waste gas containing carbon dioxide is 0.5-2h; and / or, The conveying rate of the slag is 0.5-1.5 m / min.

9. The method for carbon fixation in steel slag according to claim 8, characterized in that: More than 50% of the particles in the steel slag have a particle size of ≤80 μm; and / or, Before feeding, the moisture content of the steel slag is 5-15%; and / or, The water is at least one of industrial wastewater and reclaimed water.

10. Use of steel slag obtained by the steel slag carbon fixation device according to claim 1 or steel slag obtained by the steel slag carbon fixation method according to any one of claims 2 to 9 in building materials or road construction materials.

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