Method and device for preparing carbon sequestration steel slag powder

Abstract

The invention discloses a method and a device for preparing carbon-sequestration steel slag powder, which are characterized in that additive powder and water are uniformly mixed, an additive liquid agent accounts for 2-20% of the mass of the steel slag powder, the liquid-solid mass ratio is 5-30%, and the mixture is placed in the device for suspension reaction for 5-60 minutes according to the gas velocity of 0.5-25 m / s, the flow rate of 0.001-0.050 m < 3 > / s, the temperature of 20-60 DEG C, the relative humidity of 50-99% and the CO2 concentration of 10-99% to obtain the carbon-sequestration steel slag powder with different carbon sequestration rates. CO2 can be industrial flue gas generated under normal pressure in cement plants, steel mills, thermal power plants, petrochemical enterprises and the like, and can also be collected and concentrated by the industrial flue gas without purification. The device assembly comprises an induced draft fan, an induced draft pipe, a bottom plate, a reaction cavity, an air outlet plate and a fixing frame. According to the method, rapid preparation of the carbon-sequestration steel slag powder can be achieved, the prepared carbon-sequestration steel slag powder can be used as an auxiliary cementing material, and multiple benefits of CO2 storage and safe utilization of steel slag are achieved.

Description

Technical Field

[0001] The invention relates to a method and a device for preparing carbon-fixing steel slag powder, and belongs to the technical field of steel slag carbon-fixing application and cement concrete material. Background Art

[0002] With the rapid development of industry, CO2 emissions have also increased. How to reduce CO2 emissions has become an urgent problem to be solved. Mineral carbonation is an effective way to achieve carbon emission reduction. Steel slag, magnesium slag, high-calcium fly ash, calcined coal gangue, carbide slag, etc., as industrial steel slags with large annual output, high inventory, and rich in calcium magnesium silicates and oxides, meet the conditions for mineral carbonation. However, in the natural environment, the reaction between steel slag and CO2 is relatively slow, and a certain reaction temperature, CO2 concentration, gas pressure and carbonization time are often required to increase the carbonization reaction rate. However, energy-intensive treatment methods such as high temperature and high pressure will produce additional carbon emissions. In addition, since the physical composition of steel slag is similar to that of cement, it can be used as an auxiliary cementitious material, but it has poor stability and limited activity, which is not conducive to promotion and application. Studies have shown that a steel slag carbon fixation rate of 10% can improve stability and greatly increase activity. However, the current method has a low carbonization rate and is not feasible for large-scale and industrialization. Therefore, there is an urgent need for a method for quickly preparing carbon-fixed steel slag powder. Summary of the invention

[0003] Technical problem: In order to overcome the problem of slow carbon fixation rate of steel slag at normal temperature and pressure in the prior art, the purpose of the present invention is to provide a method and device for preparing carbon-fixed steel slag powder, which can increase the mass transfer rate of multiphase reactions and improve the reaction rate.

[0004] Technical solution: A method for preparing solid carbon steel slag powder of the present invention comprises the following steps:

[0005] Step 1, adding the additive powder into water, and fully dissolving the additive powder in the water and mixing it by mechanical stirring to obtain an additive liquid;

[0006] Step 2, weighing steel slag powder and additive liquid, placing the steel slag powder into a mechanical mixer, then adding the additive liquid to the steel slag powder, and fully mixing the steel slag powder and the additive liquid through mechanical stirring to obtain steel slag wet powder;

[0007] Step three, weigh the wet powder of steel slag, fill it into the reaction chamber from the air outlet side of the device, cover the air outlet, move the device into the carbonization box, turn on the induced draft fan, adjust the gas speed and adjust the flow in the induced draft duct through the air flow meter, react with CO2 under the set conditions, open the bottom plate to unload and obtain carbon-fixed steel slag with different carbon fixation rates.

[0008] The types of powders added in step 1 include surfactants, acid-base leaching agents, accelerators, retarders, and microbial agents, the purpose of which is to increase the carbon fixation rate of steel slag powder.

[0009] The type of the steel slag powder in step 2 is converter steel slag, and the specific surface area is not less than 300m 2 / kg, the purpose is to provide substances that react with CO2 and increase the contact area between steel slag and CO2 in the reactor.

[0010] The mechanical stirring system in step 2 is slow stirring at 30 rpm to 90 rpm for 1 min and fast stirring at 90 rpm to 150 rpm for 0.5 min, the purpose of which is to fully mix the additive liquid with the steel slag powder.

[0011] The amount of liquid added in step 2 is 2% to 20% of the mass of the slag powder, and the liquid-to-solid mass ratio is 5% to 30%, the purpose of which is to ensure that the slag reacts with CO2 in the reactor and accelerate the reaction rate.

[0012] The maximum particle size of the wet slag powder in step 2 does not exceed 0.001 m, in order to ensure that the powder can react in suspension in the device.

[0013] The height of the wet steel slag powder filled into the device in the reaction chamber in step 3 is no more than 0.15 m, so as to ensure that the powder can react in suspension in the device.

[0014] The setting conditions in step 3 include 0.5m / s to 25m / s air speed, 0.001m 3 / s~0.050m 3 / s flow rate, 20℃~60℃ temperature, 50%~99% relative humidity, 10%~99% CO2 concentration, the reaction is 5min~60min, the wet slag powder is fully in contact with CO2, the purpose is to ensure the reaction effect of the steel slag and CO2 in the reactor and accelerate the reaction rate.

[0015] The CO2 in step three can be industrial flue gas under normal pressure from cement plants, steel plants, thermal power plants, petrochemical enterprises, etc., or it can be industrial flue gas captured and concentrated without purification.

[0016] The components of the device in step three include an induced draft fan, an induced draft duct, a bottom plate, a reaction chamber, an air outlet plate, and a fixing frame. The device is located in a carbonization box to form a reaction device and provide a carbon fixation reaction environment.

[0017] The maximum air velocity of the induced draft fan of the device in step 3 is not less than 25 m / s, so as to ensure that the powder can react in suspension in the device.

[0018] The bottom plate of the device in step 3 is detachable, the reaction chamber has an outer diameter of 0.05m and a length of 1m, and the cross-section of the air outlet plate is distributed with a circular hole matrix with a diameter of 0.003m, in order to ensure that the powder will not escape from the reaction chamber during the reaction process.

[0019] The device is located in a carbonization box, a CO2 gas cylinder is connected to the carbonization box through a pressure reducing valve, and a CO2 concentration control system controls the CO2 concentration in the carbonization box.

[0020] The device includes a base plate, an induced draft fan, an induced draft duct, an air flow meter, a reaction chamber, a fixing frame, and an air outlet plate; wherein the base plate is located at the lowest part, the reaction chamber and the fixing frame are respectively vertically fixed on the base plate, the induced draft fan is connected to the reaction chamber through the induced draft duct, the air flow meter is also provided on the induced draft duct, and the air outlet plate is located at the highest part of the reaction chamber.

[0021] Beneficial effects: According to the mass transfer driven reaction mechanism and model of CO2-liquid-mineral system, the steps of carbon fixation in steel slag powder can be briefly described as follows: (1) CO2 transmission: molecular transmission of CO2 gas between the particles of steel slag wet powder agglomerates; (2) CO2 dissolution: CO2 gas dissolves from the gas phase into the water film on the surface of the steel slag wet powder agglomerates; (3) H2CO3 formation and dissociation: hydrated CO2 forms H2CO3 and gradually dissociates into HCO3 - and CO3 2- ; (4) Cationic leaching: Minerals in the steel slag wet powder agglomerates are hydrated and leached to remove Ca 2+ and Mg 2+ Equal cations; (5) Chemical reaction: HCO3 - and CO3 2- Diffusion reaches the solid-liquid interface, chemical reactions occur to generate carbonized products (such as CaCO3, silica gel, etc.); (6) Mineral deposition: CaCO3 and other crystals grow and deposit on the surface of mineral particles. According to the theory of chemical reaction engineering, the present invention uses a suspension device to accelerate the transmission rate of CO2 molecules between wet slag powder particles; based on the principle of microbial mineralization, additives can be used to promote CO2 dissolution, H2CO3 formation and dissociation, cation leaching and other processes. Through the above scientific principles, the carbon fixation rate of steel slag is comprehensively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a device of the present invention located in the carbonization box;

[0023] Figure 2 It is the device structure of the present invention;

[0024] Figure 3 It is the reaction time for preparing carbon-fixing steel slag powder with a carbon-fixing rate of 10% according to the present invention.

[0025] The figure includes: device 1, carbonization box 2, CO2 concentration control system 3, CO2 gas cylinder 4, pressure reducing valve 5, bottom plate 101, induced draft fan 102, induced draft pipe 103, air flow meter 104, reaction chamber 105, fixing frame 106, and air outlet plate 107. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described in detail below by way of embodiments.

[0027] The device used in the method for preparing solid carbon steel slag powder is as follows: the device 1 is located in a carbonization box 2, a CO2 gas cylinder 4 is connected to the carbonization box 2 through a pressure reducing valve 5, and a CO2 concentration control system 3 controls the CO2 concentration in the carbonization box 2. The device 1 includes a bottom plate 101, an induced draft fan 102, an induced draft pipe 103, an air flow meter 104, a reaction chamber 105, a fixing frame 106, and an air outlet plate 107; wherein the bottom plate 101 is located at the bottom, the reaction chamber 105 and the fixing frame 106 are respectively vertically fixed on the bottom plate 101, the induced draft fan 102 is connected to the reaction chamber 105 through the induced draft pipe 103, an air flow meter 104 is also provided on the induced draft pipe 103, and the air outlet plate 107 is located at the top of the reaction chamber 105.

[0028] A method for preparing solid carbon steel slag powder according to the present invention comprises the following contents:

[0029] Step 1, adding the additive powder into water, and fully dissolving the additive powder in the water and mixing it by mechanical stirring to obtain an additive liquid;

[0030] Step 2, weighing steel slag powder and additive liquid, placing the steel slag powder into a mechanical mixer, then adding the additive liquid to the steel slag powder, and fully mixing the steel slag powder and the additive liquid through mechanical stirring to obtain steel slag wet powder;

[0031] Step three, weigh the wet powder of steel slag, fill it into the reaction chamber from the side of the air outlet plate of the device, cover the air outlet plate, move the device into the carbonization box, turn on the induced draft fan, adjust the gas speed and adjust the flow in the induced draft duct through the air flow meter, react with CO2 under certain conditions, open the bottom plate to unload and obtain carbon-fixed steel slag with different carbon fixation rates.

[0032] Furthermore, the types of powders added in step one include surfactants, acid-base extractants, coagulants, retarders, and microbial agents.

[0033] Furthermore, the type of the steel slag powder in step 2 is converter steel slag, and the specific surface area is not less than 300m 2 / kg.

[0034] Furthermore, the mechanical stirring system in step 2 is slow stirring at 30 rpm to 90 rpm for 1 min and fast stirring at 90 rpm to 150 rpm for 0.5 min.

[0035] Furthermore, the amount of the liquid added in step 2 is 2% to 20% of the mass of the steel slag powder, and the liquid-to-solid mass ratio is 5% to 30%.

[0036] Furthermore, the maximum particle size of the wet steel slag powder in step 2 does not exceed 0.001 m.

[0037] Furthermore, the height of the wet steel slag powder filled into the device in step three in the reaction chamber is not greater than 0.15m.

[0038] Furthermore, the setting conditions in step 3 include 0.5m / s to 25m / s gas velocity, 0.001m 3 / s~0.050m 3 / s flow rate, 20℃~60℃ temperature, 50%~99% relative humidity, 10%~99% CO2 concentration, react for 5min~60min, and the wet slag powder is fully in contact with CO2.

[0039] Furthermore, the CO2 in step three can be industrial flue gas under normal pressure from cement plants, steel plants, thermal power plants, petrochemical enterprises, etc., or it can be industrial flue gas that has been captured and concentrated, and does not require purification.

[0040] Furthermore, the components of the device in step three include an induced draft fan, an induced draft duct, a bottom plate, a reaction chamber, an air outlet plate, and a fixing frame, and the device is located in a carbonization box.

[0041] Furthermore, the maximum air velocity of the induced draft fan of the device in step three is not less than 25m / s, the bottom plate is detachable, the reaction chamber has an outer diameter of 0.05m and a length of 1m, and the cross-section of the air outlet plate is a matrix of circular holes with a diameter of 0.003m.

[0042] Furthermore, the method of using the device in step three is as follows: open the air outlet plate 107, fill the wet steel slag powder into the reaction chamber 105 from the air outlet, cover the air outlet plate 107, move the device 1 with the fixed frame 106 into the carbonization box 2, open the induced draft fan 102 to adjust the gas speed and adjust the flow of gas in the induced draft pipe 103 through the airflow meter 104, close the door of the carbonization box 2, use the temperature and humidity and CO2 concentration control system 3 to adjust the parameters, and finally open the CO2 cylinder 4 and adjust the CO2 intake speed to no more than 20L / min through the pressure reducing valve 5. When unloading, close the pressure reducing valve 5 of the CO2 cylinder 4, open the door of the carbonization box 2 and move the device 1 with the fixed frame 106 out of the carbonization box 2, open the bottom plate 101 to unload and obtain the solid carbon steel slag.

[0043] In order to illustrate that the method of the present invention can quickly prepare carbon-fixing steel slag powder and verify the beneficial effect of accelerating carbon fixation of steel slag, specifically Examples 1 to 2 and Comparative Examples 1 to 2:

[0044] Example 1

[0045] (1) The type of powder added is microbial agent.

[0046] (2) The type of steel slag powder is converter steel slag with a specific surface area of ​​358.30 m 2 / kg; the amount of added liquid agent accounts for 6% of the mass of steel slag powder, and the liquid-to-solid mass ratio is 16%; the mechanical stirring system is 60rpm slow stirring for 1min and 120rpm fast stirring for 0.5min; the maximum particle size of wet steel slag powder is 0.001m.

[0047] (3) The height of the wet steel slag powder filled into the device in the reaction chamber is 0.10m; the reaction conditions are 15m / s gas velocity, 0.03m 3 / s flow rate, 30℃ temperature, 90% relative humidity, 20% CO2 concentration, react for 0.33h to obtain solid carbon steel slag; the device components include induced draft fan, induced draft duct, bottom plate, reaction chamber, air outlet plate, and fixed frame. The device is located in the carbonization box. The maximum gas velocity of the induced draft fan is 25m / s. The outer diameter of the reaction chamber is 0.05m and the length is 1m. The cross-section of the air outlet plate is a circular hole matrix with a diameter of 0.003m.

[0048] According to the national standard GB / T 19281 "Calcium Carbonate Analysis Method", the carbon fixation rate (loss on ignition) of the carbon-fixing steel slag powder of the present invention is tested to be 9.96%.

[0049] Example 2

[0050] On the basis of Example 1, the difference from Example 1 is that: in step (2), the amount of added liquid agent accounts for 0% of the mass of the steel slag powder; in step (3), the reaction is carried out for 4.00 hours to obtain solid carbon steel slag.

[0051] According to the national standard GB / T 19281-2014 "Calcium Carbonate Analysis Method", the carbon fixation rate (loss on ignition) of the carbon-fixing steel slag powder of the present invention is tested to be 9.90%.

[0052] Comparative Example 1

[0053] (1) The type of powder added is microbial agent.

[0054] (2) The type of steel slag powder is converter steel slag with a specific surface area of ​​358.30 m 2 / kg; the amount of added liquid agent accounts for 6% of the mass of steel slag powder, and the liquid-to-solid mass ratio is 16%; the mechanical stirring system is 60rpm slow stirring for 1min and 120rpm fast stirring for 0.5min; the maximum particle size of wet steel slag powder is 0.001m.

[0055] (3) The height of the wet steel slag powder filled into the device in the reaction chamber is 0.10m; the reaction conditions are 0m / s gas velocity, 0m 3 / s flow rate, 30℃ temperature, 90% relative humidity, 20% CO2 concentration, react for 1.00h to obtain solid carbon steel slag; the device components include induced draft fan, induced draft duct, bottom plate, reaction chamber, air outlet plate, and fixed frame. The device is located in the carbonization box. The maximum gas velocity of the induced draft fan is 25m / s. The outer diameter of the reaction chamber is 0.05m and the length is 1m. The cross-section of the air outlet plate is a circular hole matrix with a diameter of 0.003m.

[0056] According to the national standard GB / T 19281-2014 "Calcium Carbonate Analysis Method", the carbon fixation rate (loss on ignition) of the carbon-fixing steel slag powder of the present invention is tested to be 9.95%.

[0057] Comparative Example 2

[0058] On the basis of comparative example 1, the difference from comparative example 1 is that in step (2), the amount of added liquid agent is 0% by mass of the steel slag powder; in step (3), the reaction is carried out for 24.00 hours to obtain solid carbon steel slag.

[0059] According to the national standard GB / T 19281-2014 "Calcium Carbonate Analysis Method", the carbon fixation rate (loss on ignition) of the carbon-fixing steel slag powder of the present invention is tested to be 9.40%.

[0060] Table 1 Related test results of embodiments and comparative examples

[0061]

[0062]

[0063] The test results of carbon-fixing steel slag powder are shown in Table 1. It can be seen from Example 1 and Comparative Example 1 that the time for the carbon fixation rate of the suspended reaction of Example 1 to reach about 10% is only 0.33h, while the time for the carbon fixation rate of the static reaction of Comparative Example 1 to reach about 10% is 1.00h; it can be seen from Example 2 and Comparative Example 2 that the time for the carbon fixation rate of the suspended reaction of Example 2 to reach about 10% is 4.00h, while the time for the carbon fixation rate of the static reaction of Comparative Example 2 to reach about 10% is more than 24.00h, indicating that regardless of whether microbial additives are used, the carbon fixation rate of steel slag after using the method of the present invention is faster.

[0064] It can be seen from Examples 1 to 2 that the time it takes for the carbon fixation rate of the suspended reaction with additives in Example 1 to reach about 10% is only 0.33 h, while the time it takes for the carbon fixation rate of the suspended reaction without additives in Example 2 to reach about 10% is 4.00 h; it can be seen from Comparative Examples 1 to 2 that the time it takes for the carbon fixation rate of the static reaction with additives in Comparative Example 1 to reach about 10% is 1.00 h, while the time it takes for the carbon fixation rate of the static reaction without additives in Comparative Example 2 to reach about 10% is more than 24.00 h, indicating that the use of microbial additives can accelerate the carbon fixation rate of steel slag.

Claims

1. A method for preparing solid carbon steel slag powder, characterized in that: The method comprises the following steps: Step 1, adding the additive powder into water, and fully dissolving the additive powder in the water and mixing it by mechanical stirring to obtain an additive liquid; Step 2: Take steel slag powder and additive liquid, put the steel slag powder into a mechanical mixer, then add the additive liquid to the steel slag powder, and fully mix the steel slag powder and the additive liquid through mechanical stirring to obtain steel slag wet powder; Step three, take the wet steel slag powder, fill it into the reaction chamber (105) from the side of the air outlet plate (107) of the device, cover the air outlet plate (107), move the device (1) into the carbonization box (2), turn on the induced draft fan (102), adjust the gas speed and adjust the flow in the induced draft pipe (103) through the air flow meter (104), react with CO2 under the set conditions, open the bottom plate (101) to unload and obtain carbon-fixed steel slag powder with different carbon fixation rates.

2. The method for preparing solid carbon steel slag powder according to claim 1, characterized in that: In the step 1, the types of powders added include surfactants, acid-base extractants, coagulants, retarders, and microbial agents.

3. The method for preparing solid carbon steel slag powder according to claim 1, characterized in that: In step 2, the type of steel slag powder is converter steel slag and the specific surface area is not less than 300m 2 / kg, the mechanical stirring system is 30rpm ~ 90rpm slow stirring for 1min, 90rpm ~ 150rpm fast stirring for 0.5min.

4. The method for preparing solid carbon steel slag powder according to claim 1, characterized in that: In the step 2, the amount of the added liquid agent is 2% to 20% of the mass of the steel slag powder, and the liquid-to-solid mass ratio is 5% to 30%.

5. The method for preparing solid carbon steel slag powder according to claim 1, characterized in that: In the step 2, the maximum particle size of the wet slag powder does not exceed 0.001 m.

6. The method for preparing solid carbon steel slag powder according to claim 1, characterized in that: In the step 3, the height of the wet steel slag powder filled into the device in the reaction chamber is not more than 0.15m.

7. The method for preparing solid carbon steel slag powder according to claim 1, characterized in that: In step 3, the setting conditions include 0.5m / s to 25m / s air velocity, 0.001m 3 / s~0.050m 3 / s flow rate, 20℃~60℃ temperature, 50%~99% relative humidity, 10%~99% CO2 concentration, react for 5min~60min, and the wet slag powder is fully in contact with CO2.

8. The method for preparing solid carbon steel slag powder according to claim 1, characterized in that: In step three, CO2 is industrial flue gas under normal pressure from cement plants, steel plants, thermal power plants, and petrochemical enterprises, or is industrial flue gas captured and concentrated, and does not need to be purified.

9. An apparatus used in the method for preparing solid carbon steel slag powder as claimed in claim 1, characterized in that: The device (1) is located in a carbonization box (2), a CO2 gas cylinder (4) is connected to the carbonization box (2) via a pressure reducing valve (5), and a CO2 concentration control system (3) controls the CO2 concentration in the carbonization box (2).

10. The device used in the method for preparing solid carbon steel slag powder according to claim 9, characterized in that: The device (1) comprises a base plate (101), an induced draft fan (102), an induced draft pipe (103), an air flow meter (104), a reaction chamber (105), a fixing frame (106), and an air outlet plate (107); wherein the base plate (101) is located at the bottom, the reaction chamber (105) and the fixing frame (106) are respectively vertically fixed on the base plate (101), the induced draft fan (102) is connected to the reaction chamber (105) via the induced draft pipe (103), an air flow meter (104) is also provided on the induced draft pipe (103), and the air outlet plate (107) is located at the top of the reaction chamber (105).

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