Apparatus and method for fixing carbon dioxide in steel slag

Abstract

This application relates to the field of industrial waste recycling, specifically to an apparatus and method for carbon dioxide fixation of steel slag. The apparatus for carbon dioxide fixation of steel slag includes an apparatus main body, a spray device provided at the top of the apparatus main body, and an exhaust port. The apparatus main body is further provided with a supply port, a discharge port, and an intake port. A conveying unit is provided inside the apparatus main body, and the conveying unit includes multiple conveying mechanisms. The apparatus can achieve carbon dioxide fixation of steel slag by injecting carbon dioxide-containing industrial exhaust gas into the steel slag while maintaining an ambient humidity of 80-100%. By controlling the ambient humidity, the present application maintains the moisture content of the steel slag during the reaction with carbon dioxide, shortens the contact time between water and the steel slag, prevents the elution of calcium element from the steel slag, and forms a water film on the surface of the steel slag without interfering with the reaction between carbon dioxide and free calcium oxide in the steel slag, thereby allowing the reaction between carbon dioxide and free calcium oxide to proceed more efficiently.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority from a Chinese patent application bearing application number 202310911825.8 and entitled "Apparatus and method for fixing carbon dioxide in steel slag," filed with the China Patent Office on July 24, 2023, the entire contents of which are incorporated herein by reference.

[0002] [Technical field] The present application relates to the field of recycling industrial waste, and more particularly to an apparatus and method for fixing carbon dioxide in steel slag. [Background technology]

[0003] Steel slag is a major by-product of the steelmaking process. While a large amount of steel slag is generated each year, 60% of it remains unused. Therefore, its recycling is crucial. The main reason for the limited recycling of steel slag is its large amount of unstable free calcium oxide. On the one hand, the high content of free calcium oxide in steel slag makes it prone to swelling and shattering, resulting in poor volume stability. Furthermore, its use in road engineering can lead to a series of quality issues, such as pavement swelling and cracking. On the other hand, the reduction of free calcium oxide in steel slag is unstable, making it difficult to maintain at a low level. Currently, the reaction of free calcium oxide in steel slag with carbon dioxide to form calcium carbonate effectively improves the stability of steel slag, expanding its applications and reducing carbon dioxide emissions. This has the dual benefits of reducing carbon dioxide emissions and recycling solid waste.

[0004] Prior art has mainly disclosed a method for CO2 fixation and slaking free calcium oxide in steel slag powder, in which the steel slag after soaking is stably reacted with waste heat flue gas containing carbon dioxide in a mill to fix the carbon dioxide and slaking the free calcium oxide. However, this method has the drawback that excess water remains on the surface of the steel slag during soaking, forming a water film that prevents contact between the carbon dioxide and the free calcium oxide in the steel slag. Furthermore, soaking the steel slag causes the elution of calcium elements other than the free calcium oxide, making it necessary to reprocess the wastewater after soaking the steel slag, which increases resource utilization costs and reduces the carbon dioxide fixation rate of the steel slag due to the loss of calcium elements. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, the technical problem to be solved by the present application is to provide an apparatus and method for carbon dioxide fixation in steel slag that improves the carbon dioxide fixation rate of steel slag, in order to overcome the deficiencies of the prior art, such as the formation of a water film when the steel slag is immersed, which prevents contact between carbon dioxide and the free calcium oxide in the steel slag, resulting in increased wastewater retreatment costs and a low carbon dioxide fixation rate in the steel slag due to the loss of calcium element in the steel slag. [Means for solving the problem]

[0006] According to one aspect, the present application provides an apparatus for fixing carbon dioxide in steel slag, comprising: an apparatus main body; a spray device and an exhaust port provided on an upper portion of the structure of the apparatus main body; the apparatus main body further comprising a supply port, a discharge port, and an air intake port; the supply port is located higher than the discharge port, the air intake port is located between the supply port and the discharge port; and a transport unit is provided inside the apparatus main body, the transport unit including a plurality of transport mechanisms.

[0007] According to another aspect, the present application provides a method for immobilizing carbon dioxide in steel slag, the method comprising the step of injecting industrial exhaust gas containing carbon dioxide into steel slag under conditions of an environmental humidity of 80 to 100%.

[0008] The carbon dioxide-containing industrial exhaust gas further contains SO2, and optionally the volume content of SO2 is 100-300 ppm.

[0009] The environmental humidity is controlled by the amount of spray water.

[0010] The amount of industrial waste gas injected is 150,000 to 230,000 m 3 The supply amount of the iron and steel slag is 1 to 1.5 t / h.

[0011] The volume content of CO2 in the carbon dioxide-containing industrial exhaust gas is ≧10%, optionally the volume content of CO2 is ≧25%, and the temperature of the industrial exhaust gas is 100-200°C.

[0012] During the reaction process between the steel slag and the carbon dioxide-containing industrial exhaust gas, the pressure intensity is 1 to 1.5 atm.

[0013] The contact time between the steel slag and the carbon dioxide-containing industrial exhaust gas is 0.5 to 2 hours, and the conveying speed of the steel slag is 0.5 to 1.5 m / min.

[0014] The particle size of 50% or more of the steel slag is ≦80 μm, and the water content of the steel slag before being supplied is 5-15%, and the water is at least one of industrial wastewater or recycled water.

[0015] The steel slag obtained by the apparatus for carbon dioxide fixation from steel slag according to the present application or the steel slag obtained by the method for carbon dioxide fixation from steel slag according to the present application can be used as a building material or a road construction material. [Effects of the Invention]

[0016] The technical solution of the present application has the following advantages:

[0017] 1. The present invention provides an apparatus for carbon dioxide fixation of steel slag, comprising an apparatus main body, a spray device disposed on the upper part of the apparatus main body, and an exhaust port. The apparatus main body is further provided with a supply port, an exhaust port, and an air intake port. The supply port is located higher than the exhaust port, and the air intake port is located between the supply port and the exhaust port. A conveying unit is disposed inside the apparatus main body, and the conveying unit includes a plurality of conveying mechanisms. The spray device disposed on the upper part of the apparatus main body facilitates spraying water into the apparatus, ensuring that the environmental humidity inside the apparatus meets the required level. The air intake port is disposed between the supply port and the exhaust port, which is advantageous for ensuring that the industrial exhaust gas supplied through the supply port is in sufficient contact with the steel slag, preventing the industrial exhaust gas injected into the apparatus from overflowing through the gas outlet without reacting with the steel slag. Furthermore, the present invention provides a conveying unit formed of a plurality of conveying mechanisms, which allows the conveying speed of each conveying mechanism to be controlled to ensure sufficient time for the steel slag and the industrial exhaust gas to react with each other inside the apparatus.

[0018] 2. The method for immobilizing carbon dioxide in steel slag according to the present invention includes injecting industrial exhaust gas containing carbon dioxide into steel slag under conditions of an ambient humidity of 80 to 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 contact between water and the steel slag, and prevents the elution of calcium element in the steel slag, thereby allowing the reaction of immobilizing carbon dioxide in the steel slag to proceed sufficiently, and does not form a water film on the surface of the steel slag to interfere with the reaction between carbon dioxide and free calcium oxide in the steel slag. By maintaining the ambient humidity, the present invention allows the reaction between carbon dioxide and free calcium oxide in the steel slag to proceed more efficiently.

[0019] 3. According to the method for immobilizing carbon dioxide in steel slag of the present application, the industrial exhaust gas that reacts with the free calcium oxide in the steel slag contains sulfur dioxide in addition to carbon dioxide. In the present application, industrial exhaust gas containing sulfur dioxide and carbon dioxide is injected and allowed to react with the steel slag. The sulfurous acid and sulfuric acid produced by the addition of sulfur dioxide react with and dissolve compounds on the surface of the steel slag, forming gaps that allow the carbon dioxide to penetrate deeper into the steel slag and react with the free calcium oxide inside the slag, improving the efficiency of carbon dioxide immobilization.

[0020] 4. According to the method for immobilizing carbon dioxide in steel slag of the present application, while spraying water droplets during the process of immobilizing carbon dioxide in steel slag, the conveying speed of the steel slag is controlled to 0.5 to 1.5 m / min and the contact time between the steel slag and industrial exhaust gas is controlled to 0.5 to 2 hours, thereby ensuring that the steel slag is in sufficient contact with the sprayed water droplets, ensuring that the moisture content of the steel slag that reacts with the carbon dioxide-containing industrial exhaust gas meets the standard, and improving the reaction efficiency of the carbon dioxide immobilization in the steel slag.

[0021] 5. According to the method for carbon dioxide fixation in steel slag of the present application, the steel slag after carbon dioxide fixation has a low content of free calcium oxide and can be used as a building material or road construction material. The carbon dioxide fixation process is simple, and industrial exhaust gas and industrial reclaimed water can be effectively consumed. [Brief explanation of the drawings]

[0022] In order to more clearly describe the specific embodiments of the present application or the technical solutions of the prior art, the drawings necessary for describing the specific embodiments or the prior art will be briefly described below. It will be apparent that the drawings described below are some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without any creative work.

[0023] [Figure 1] 1 is a structural schematic diagram of an apparatus for fixing carbon dioxide in steel slag according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following examples are provided for a better understanding of the present application, but are not limited to the best embodiment and do not constitute limitations on the content and scope of protection of the present application. Any products that are the same as or similar to the present application obtained under the suggestion of the present application or by combining the present application with other prior art features are all included in the scope of protection of the present application.

[0025] Unless specific experimental procedures or conditions are given in the examples, they may be carried out in accordance with the procedures or conditions of conventional experimental procedures described in the literature in the field. Unless the manufacturers of the reagents or instruments used are given, they are all commercially available conventional reagent products.

[0026] The present application provides an apparatus for fixing carbon dioxide in steel slag, and as shown in FIG. 1, the apparatus for fixing carbon dioxide in steel slag includes an apparatus main body 6, a spray device 4 and an exhaust port 5 provided on the upper part of the structure of the apparatus main body 6, the apparatus main body 6 further includes a supply port 3, a discharge port 1 and an intake port 2, the supply port 3 is located higher than the discharge port 1, the intake port 2 is located between the supply port 3 and the discharge port 1, a transport unit 7 is provided inside the apparatus main body 6, the transport unit 7 includes a plurality of transport mechanisms, and during use Steel slag with a moisture content that meets the requirements is fed into the conveying mechanism through the supply port 3, the angle of which can be adjusted as desired to ensure that the steel slag is spread as thinly as possible on the conveying mechanism, and the conveying mechanism conveys the steel slag. During transportation, industrial exhaust gas containing carbon dioxide or containing carbon dioxide and sulfur dioxide is injected through the intake port 2, and recycled water or industrial wastewater is sprayed through the spray device 4, maintaining the ambient humidity within the device body 6, and the steel slag with carbon dioxide fixed is discharged through the discharge port 1.

[0027] Specifically, the supply method of the present application can employ screw supply, conveyor supply, vibration supply, etc., and is preferably a vibration supply method, which maintains a constant vibration frequency to allow the steel slag to be spread more uniformly on the conveyor unit 7.

[0028] Specifically, the discharge method of the present application can be screw discharge, conveyor discharge, vibration discharge, etc., and preferably vibration discharge, which is more advantageous for discharging the steel slag and prevents the steel slag from adhering to the discharge port 1 due to excessive humidity.

[0029] Specifically, the present application does not limit the type, material, number, or installation location of the conveying mechanism of the conveying unit 7, as long as it can convey the steel slag. The angle between each conveying mechanism and the horizontal line is set as the inclination angle of the conveying mechanism, and the inclination angle of the conveying mechanism can be adjusted arbitrarily, thereby ensuring that the steel slag is laid as thinly as possible on the conveying mechanism. The conveying mechanism of the present application may be a conveyor belt, each of which is provided with protrusions to increase the friction between the belt and the steel slag, and each conveyor belt is provided at a certain inclination angle, so that the steel slag on the previous conveyor belt falls onto the next conveyor belt under the action of gravity. The present application provides one alternative embodiment, in which the conveying mechanism is two conveyor belts, one end of the first conveyor belt is provided at the supply port and is used to receive the steel slag from the supply port 3, and the other end of the first conveyor belt is provided above one end of the second conveyor belt, which is used to receive the steel slag on the first conveyor belt and transport it to the discharge port 1. The provision of two conveyor belts allows the steel slag to be better spread and to be fully exposed to industrial exhaust gases.

[0030] Specifically, the present application does not limit the type, installation location, or number of spray devices 4, as long as the environmental humidity inside the device can be maintained at 80 to 100%. Optionally, the spray devices 4 are multiple droplet spray devices that are uniformly installed on the top of the device to ensure uniform environmental humidity inside the device.

[0031] In the examples and comparative examples of the present application, the initial free calcium oxide content of the steel slag before carbon dioxide fixation is 8%, the chlorine content is 0.015%, and the sulfur content is 0.07%.

[0032] Example 1 This embodiment provides a method for immobilizing carbon dioxide in steel slag, and the specific steps and method are as follows:

[0033] 1. Before feeding, the proportion of steel slag with a particle size of ≦80 μm was controlled to 50%, and the moisture content of the steel slag was kept at 10%. The moisture content of the steel slag was controlled by spraying water onto the steel slag.

[0034] 2. The supply rate of steel slag was 1t / h, and the inclination angle of the conveying mechanism was controlled to 15°.

[0035] 3. Continuously spray recycled water droplets into the device to maintain the humidity inside the device at 80%. At the same time, inject CO2-containing industrial exhaust gas. The volume ratio of CO2 in the CO2-containing industrial exhaust gas is ≥ 25%. The injection amount of industrial exhaust gas is 150,000 m 3 / h, the temperature of the industrial exhaust gas was 150°C, and the pressure strength of the device body was 1.5 atm.

[0036] 4. The conveying speed of the conveying mechanism was controlled to 1 m / min, and the operating time of the steel slag in the device was 1 hour, that is, the contact time between the steel slag and the industrial exhaust gas in the device body was 1 hour.

[0037] Example 2 This embodiment provides a method for immobilizing carbon dioxide in steel slag, and the specific steps and methods are as follows:

[0038] 1. Before feeding, the proportion of steel slag with a particle size of ≦80 μm was controlled to 70%, and the moisture content of the steel slag was kept at 5%. The moisture content of the steel slag was controlled by spraying water onto the steel slag.

[0039] 2. The supply rate of steel slag was 1.5t / h, and the inclination angle of the conveying mechanism was controlled to 25°.

[0040] 3. Continuously spray industrial wastewater droplets into the device to maintain the humidity in the device at 100%. At the same time, inject CO2-containing industrial exhaust gas. The volume ratio of CO2 in the CO2-containing industrial exhaust gas is ≥ 30%. The injection amount of industrial exhaust gas is 200,000 m 3 / h, the temperature of the industrial exhaust gas was 200°C, and the pressure inside the device was 1 atm.

[0041] 4. The conveying speed of the conveying mechanism was controlled to 1.5 m / min, and the operating time of the steel slag in the device was 2 hours, that is, the contact time between the steel slag and the industrial exhaust gas in the device body was 2 hours.

[0042] Example 3 This embodiment provides a method for immobilizing carbon dioxide in steel slag, and the specific steps and method are as follows:

[0043] 1. Before feeding, the proportion of steel slag with a particle size of ≦80 μm was controlled to 50%, and the moisture content of the steel slag was kept at 10%. The moisture content of the steel slag was controlled by spraying water onto the steel slag.

[0044] 2. The supply rate of steel slag was 1t / h, and the inclination angle of the conveying mechanism was controlled to 15°.

[0045] 3. Continuously spray recycled water droplets into the device to maintain the humidity inside the device at 80%. At the same time, inject CO2-containing industrial exhaust gas. The volume ratio of CO2 in the CO2-containing industrial exhaust gas is ≥ 25%, the volume content of SO2 is 150 ppm, and the injection amount of industrial exhaust gas is 150,000 m 3 / h, the temperature of the industrial exhaust gas was 150°C, and the pressure strength of the device body was 1.5 atm.

[0046] 4. The conveying speed of the conveying mechanism was controlled to 1 m / min, and the operating time of the steel slag in the device was 1 hour, that is, the contact time between the steel slag and the industrial exhaust gas in the device body was 1 hour.

[0047] Example 4 This embodiment provides a method for immobilizing carbon dioxide in steel slag, and the specific steps and methods are as follows:

[0048] 1. Before feeding, the proportion of steel slag with a particle size of ≦80 μm was controlled to 50%, and the moisture content of the steel slag was kept at 15%. The moisture content of the steel slag was controlled by spraying water onto the steel slag.

[0049] 2. The supply rate of steel slag was 1.2 t / h, and the inclination angle of the conveying mechanism was controlled to 15°.

[0050] 3. Continuously spray industrial wastewater droplets into the device to maintain the humidity inside the device at 90%. At the same time, inject CO2-containing industrial exhaust gas. The volume ratio of CO2 in the CO2-containing industrial exhaust gas is ≥ 10%, the volume content of SO2 is 250 ppm, and the injection amount of industrial exhaust gas is 230,000 m 3 / h, the temperature of the industrial exhaust gas was 100°C, and the pressure inside the device was 1.2 atm.

[0051] 4. The conveying speed of the conveying mechanism was controlled to 0.5 m / min, and the operating time of the steel slag in the device was 0.5 h, that is, the contact time between the steel slag and the industrial exhaust gas in the device body was 0.5 h.

[0052] Example 5 This example provides a method for immobilizing carbon dioxide in steel slag, and the specific steps and methods are the same as those in Example 3, except that the volume content of SO2 in the industrial exhaust gas is 300 ppm.

[0053] Example 6 This embodiment provides a method for immobilizing carbon dioxide in steel slag, and the specific steps and method are the same as those in Example 1, except that the moisture content of the supplied steel slag is controlled by immersion.

[0054] Example 7 This embodiment provides a method for immobilizing carbon dioxide in steel slag, and the specific steps and method are as follows:

[0055] Before feeding, the proportion of steel slag with a particle size of 80 μm or less is controlled to 70%, and the moisture content of the steel slag is maintained at 5%. The moisture content of the steel slag is controlled by spraying water onto the steel slag. Using the structure shown in Figure 1, the steel slag with a moisture content that meets the standard is transported to the transport mechanism via the feed port 3 at a feed rate of 1 t / h. The transport mechanism consists of two conveyor belts, and the inclination angles of the two conveyor belts are both controlled to 25°, so that the steel slag at the discharge port 1 is The steel slag can be spread evenly on the conveyor belt, and under the action of gravity, the steel slag on the previous conveyor belt can fall onto the next conveyor belt. While the steel slag is being transported within the device body 6, the spray device 4 continuously sprays recycled water droplets onto the device body 6 to maintain the humidity within the device body 6 at 100%. At the same time, the air inlet 2 blows CO2-containing industrial exhaust gas into the device body 6, and the proportion of CO2 in the CO2-containing industrial exhaust gas is ≥ 15%, and the injection amount of industrial exhaust gas is 150,000 m 3 / h, the transport speed of each conveyor belt was controlled to 1.5 m / min, the operating time of the steel slag in the device body 6 was set to 2 hours, and the steel slag after carbon dioxide fixation was discharged from the discharge outlet 1.

[0056] Comparative Example 1 The comparative example of the present application provides a method for immobilizing carbon dioxide in steel slag, and the specific steps and methods are the same as those in Example 1, except that the ambient humidity in the apparatus for immobilizing carbon dioxide in steel slag is maintained at 60%.

[0057] Comparative Example 2 The comparative example of the present application provides a method for fixing carbon dioxide in steel slag, and the specific steps and methods are the same as those in Example 1, except that no spraying is performed during the process of fixing carbon dioxide in steel slag.

[0058] Experimental example The free calcium oxide content, chlorine content, and sulfur content of the steel slag treated by the carbon dioxide fixation method for steel slag in Examples 1 to 5 and Comparative Examples 1 and 2 were determined. The determination method adopted was YB / T140-2009 "Method for Chemical Analysis of Steel Slag." The detection results are shown in Table 1.

[0059] [Table 1]

[0060] The free calcium oxide, chlorine content, and sulfur content of the steel slag treated by the method for immobilizing carbon dioxide in steel slag in Examples 1 to 5 of the present application all meet the requirements for the chemical composition of steel slag powder in the national standard GB / T 20491-2017. The free calcium oxide content of the steel slag produced by this method is much lower than the specified standard, and therefore the steel slag produced by this method also has wider applicability.

[0061] It is apparent that the above examples are merely illustrative and do not limit the embodiments. Those skilled in the art can make various other modifications and variations based on the above description. It is not necessary or possible to cover all embodiments here. Any obvious modifications and variations derived therefrom still fall within the scope of protection of the present invention. [Explanation of symbols]

[0062] 1 - outlet, 2 - intake, 3 - supply, 4 - spray device, 5 - exhaust, 6 - device body, 7 - conveying unit.

Claims

1. An apparatus for fixing carbon dioxide in steel slag, comprising: an apparatus main body (6); a spray device (4) and an exhaust port (5) provided in an upper portion of the structure of the apparatus main body (6); the apparatus main body (6) is further provided with a supply port (3), a discharge port (1) and an air intake port (2); the supply port (3) is positioned higher than the discharge port (1); the air intake port (2) is located between the supply port (3) and the discharge port (1); a transport unit (7) is provided inside the apparatus main body (6), and the transport unit (7) includes a plurality of transport mechanisms.

2. A method for fixing carbon dioxide in iron and steel slag, comprising: A method for immobilizing carbon dioxide in steel slag, comprising the step of injecting industrial exhaust gas containing carbon dioxide into steel slag under conditions of an environmental humidity of 80 to 100%.

3. The carbon dioxide-containing industrial exhaust gas contains SO 2 and optionally, SO 2 The method for fixing carbon dioxide in iron and steel slag according to claim 2, characterized in that the volume content of is 100 to 300 ppm.

4. 4. The method for fixing carbon dioxide in iron and steel slag according to claim 3, wherein the environmental humidity is controlled by the amount of spray water.

5. The injection volume of the industrial exhaust gas is 150,000 to 230,000 m 3 / h, and / or The method for fixing carbon dioxide with iron and steel slag according to claim 4, characterized in that the supply amount of the iron and steel slag is 1 to 1.5 t / h.

6. CO in the carbon dioxide-containing industrial exhaust gas 2 The volume content of is ≥ 10%, and optionally CO 2 The volume content of is ≧25%; And / or, the temperature of the industrial exhaust gas is 100 to 200°C, The method for fixation of carbon dioxide in steel slag according to claim 5.

7. 7. The method for fixing carbon dioxide in steel slag according to claim 6, wherein the pressure intensity during the reaction between the steel slag and the carbon dioxide-containing industrial exhaust gas is 1 to 1.5 atm.

8. The contact time between the iron and steel slag and the carbon dioxide-containing industrial exhaust gas is 0.5 to 2 hours, and / or The method for fixing carbon dioxide in steel slag according to any one of claims 2 to 7, characterized in that the conveying speed of the steel slag is 0.5 to 1.5 m / min.

9. 50% or more of the particle size in the iron and steel slag is ≦80 μm, and / or Before being fed, the water content of the iron and steel slag is 5 to 15%; and / or 9. The method for fixing carbon dioxide in steel slag according to claim 8, wherein the water is at least one of industrial wastewater and recycled water.

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

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