System and method for carbon dioxide fixation by steel slag tailings

Abstract

The present application belongs to the technical field of steel slag tailing resource utilization, and particularly relates to a system and method for fixing carbon dioxide by using steel slag tailing. The system comprises a carbon fixation reaction device, a mixing device, a brick making device and a curing device. The top of the carbon fixation reaction device is provided with a steel slag tailing inlet and a water outlet, the bottom of the carbon fixation reaction device is provided with an air inlet, the inside of the carbon fixation reaction device is provided with a spraying device, and the side wall of the carbon fixation reaction device is provided with a discharge outlet. The mixing device is used for receiving the carbon fixation steel slag from the discharge outlet and mixing the carbon fixation steel slag, water, cement and additive to obtain a mixture. The brick making device is used for making the mixture obtained from the mixing device into a water permeable brick. The curing device is used for making the water permeable brick prepared from the brick making device to have a carbon fixation reaction with carbon dioxide to obtain a steel slag water permeable brick. The present application solves the problem that the utilization range of steel slag tailing is limited due to the fine carbon fixation effect, and the prepared water permeable brick has good compressive strength.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of steel slag tailings resource utilization, and particularly relates to a system and method for fixing carbon dioxide by using steel slag tailings. BACKGROUND

[0002] CO2 storage and fixation technologies mainly include geological storage, ocean storage and mineral carbonation fixation. Mineral carbonation fixation is the best choice due to its high thermal stability, environmental friendliness and low raw material cost. Steel slag is a byproduct of steelmaking. Steel slag tailings are widely used in road construction, building materials and other industries, and mainly used in cement production, road construction, concrete production, etc. However, the f-CaO and f-MgO in the slag are easy to react with CO2, causing volume expansion and thus causing harm, so its use is limited.

[0003] Chinese patent 201910960172.6 proposes a steel slag crushing and carbon fixation treatment system and its application. The molten steel slag is crushed to a particle size of less than 2 mm, and then the steel slag powder is reacted with carbon dioxide and superheated steam in a fluidized reactor to form stable calcium carbonate. Chinese patent 202210599827.3 proposes a method and application for carbon fixation and emission reduction of wet-milled steel slag in a steel plant. The molten steel slag is broken, de-ironed and dry-milled after water quenching and rapid cooling to obtain steel slag with a median particle size of 20-500 μm. The steel slag powder and water are stirred in proportion to form a steel slag slurry for carbon fixation, and the carbon fixation is dried to obtain a CO2 solidification material. Chinese patent 202211142705.8 proposes a steel slag carbon fixation device and its use method, which provides a method for making steel slag powder and carbon dioxide in air fully contact by prolonging the residence time of steel slag powder in air, and then making the steel slag powder and carbon dioxide fully react for carbon fixation. Chinese patent 202310911825.8 proposes a device and method for steel slag carbon fixation. The steel slag with more than 50% of particle size ≤80 μm is kept in a carbon fixation device under the condition of 80-100% relative humidity, and industrial waste gas containing carbon dioxide is introduced into the steel slag to realize steel slag carbon fixation. As can be seen, the existing technology improves the carbon fixation effect by refining the steel slag. However, the refined steel slag powder is mainly used in the cement industry, and most of it is used as a cement mixing material. The implementation of GB175-2023 "General Portland Cement" on June 1, 2024, makes steel slag unable to be used as a mixing material for general Portland cement, which has an adverse effect on the resource utilization of steel slag after carbon fixation and the ecological environment. SUMMARY

[0004] The purpose of this invention is to address the deficiency in existing technologies where carbon-fixed steel slag powder can no longer be used as a blending material for general-purpose silicate cement. Therefore, this invention proposes a system and method for fixing carbon dioxide in steel slag tailings. First, the invention utilizes steel slag tailings to undergo a primary carbon fixation reaction with carbon dioxide. Then, the steel slag from the primary carbon fixation reaction is used to prepare permeable bricks. During the curing period of the permeable bricks, carbon dioxide is introduced to conduct a secondary carbon fixation reaction, resulting in permeable steel slag bricks. This invention enables carbon fixation of steel slag tailings of all particle sizes, allowing for the full utilization and secondary carbon fixation of the carbon-fixed steel slag. It solves the problem of limited utilization of steel slag tailings due to the reliance on refining to improve carbon fixation. Simultaneously, the prepared permeable steel slag bricks exhibit good compressive strength.

[0005] The first aspect of this invention proposes a system for fixing carbon dioxide from steel slag tailings. This system includes a carbon fixation reaction device, a mixing device, a brick-making device, and a curing device. The top of the carbon fixation reaction device is provided with a steel slag tailings inlet and a water outlet, the bottom of the carbon fixation reaction device has an air inlet, the interior of the carbon fixation reaction device is equipped with a spray device, and the side wall of the carbon fixation reaction device has a discharge outlet. The mixing device is used to receive the carbon-fixed steel slag from the discharge outlet and mix the carbon-fixed steel slag, water, cement, and additives to obtain a mixture. The brick-making device is used to make permeable bricks from the mixture obtained in the mixing device. The curing device is used to react the permeable bricks prepared in the brick-making device with carbon dioxide to obtain steel slag permeable bricks.

[0006] Preferably, the bottom of the carbon fixation reactor is equipped with several rollers of gradually decreasing height along the horizontal direction, with the rollers closest to the discharge port having the smallest height, and the rollers cause the carbon fixation reactor to be in an inclined state.

[0007] Preferably, a rotating gear is fixed outside the shell of the carbon fixation reactor, and the rotating gear is connected to a conveying device, which drives the rotating gear to rotate the carbon fixation reactor.

[0008] Preferably, the top of the carbon fixation reaction device is also equipped with a pressure gauge, a pressure relief valve, and a safety valve.

[0009] A second aspect of this invention provides a method for fixing carbon dioxide in steel slag tailings, which is implemented in the system described above and includes the following steps:

[0010] S1. Steel slag tailings enter the carbon fixation reaction device through the steel slag tailings inlet. Water is sprayed into the carbon fixation reaction device through the spraying device. Carbon dioxide is introduced into the carbon fixation reaction device through the air inlet. The steel slag tailings and carbon dioxide undergo the first carbon fixation reaction. After the reaction is completed, water is discharged from the water outlet, and the carbon-fixed steel slag produced by the reaction is discharged from the discharge outlet.

[0011] S2, the discharged carbon fixation steel slag enters the mixing device, and the carbon fixation steel slag, water, cement and additives are mixed in the mixing device to obtain a mixture;

[0012] S3, the obtained mixture is input into the brick making device to make bricks to obtain water permeable bricks;

[0013] S4, the water permeable bricks are placed in the curing device, and carbon dioxide is introduced into the curing device, so that the water permeable bricks and the carbon dioxide perform a second carbon fixation reaction to obtain steel slag water permeable bricks.

[0014] Preferably, in step S1, the mass ratio of steel slag tailings to water is 1:5-10; carbon dioxide is introduced into the carbon fixation reaction device through the gas inlet, so that the pressure in the carbon fixation reaction device is 1-5 MPa.

[0015] Preferably, in step S2, the mass ratio of carbon fixation steel slag, cement, water and additives is 3.5-8:1:0.2-0.4:0.01-0.04.

[0016] Preferably, the additive includes a water reducing agent; the water reducing agent is one or more of isobutene polyoxyethylene ether, isoamylene polyoxyethylene ether and methyl methacrylate.

[0017] Preferably, in step S4, carbon dioxide with a concentration of ≥20% is introduced into the curing device.

[0018] Preferably, in step S4, the conditions of the second carbon fixation reaction include: temperature of 18-22℃, humidity of 40-90%, and time of 25-30 days.

[0019] In the system and method for fixing carbon dioxide by using steel slag tailings according to the present application, at least the following beneficial effects are achieved:

[0020] (1) In the present application, first, the steel slag tailings and carbon dioxide perform a first carbon fixation reaction, then the steel slag after the first carbon fixation reaction is used to prepare water permeable bricks, and carbon dioxide is introduced during the curing of the water permeable bricks to perform a second carbon fixation reaction to obtain steel slag water permeable bricks, which can realize the fixation of carbon dioxide by using full particle size steel slag tailings, improve the stability and realize full utilization of resources, solve the problem that the utilization range of steel slag tailings is limited due to the increase of carbon fixation effect by fine grinding; at the same time, the steel slag after the first carbon fixation reaction is used to prepare water permeable bricks, and the steel slag performs a second carbon fixation reaction, so that the unreacted CaO, MgO, f-CaO and f-MgO in the steel slag further react with CO2 to improve the carbon fixation effect, and the main minerals C3S and C2S in the cement react with CO2, and the cement hydration products Ca(OH)2 and CSH also react with CO2, which not only improves the carbon fixation effect, but also improves the strength of the steel slag water permeable bricks prepared;

[0021] (2) In the preferred case, in the first carbon fixation reaction process, through suitable solid-liquid ratio, pressure and mixing stirring, the reaction of CaO, MgO, f-CaO, f-MgO and CO2 in the steel slag can be promoted more persistently and deeply, and the carbon fixation effect is improved;

[0022] (3) In the preferred case, by reasonably controlling the conditions in the second carbon fixation reaction process, the carbonation conversion rate of the steel slag can be greater than 80%, the free calcium oxide content in the carbon fixation steel slag is reduced to below 0.5%, and the compressive strength of the steel slag permeable brick is increased by 50-200%. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of a system for fixing carbon dioxide by steel slag tailings according to the present application;

[0024] Figure 2 is a flow schematic diagram of a method for fixing carbon dioxide by steel slag tailings according to the present application.

[0025] REFERENCE NUMERALS

[0026] 1, carbon fixation reaction device; 2, mixing device; 3, brick making device; 4, curing device; 5, steel slag tailings inlet; 6, water outlet; 7, gas inlet; 8, spraying device; 9, discharge port; 10, carrier wheel; 11, rotating gear; 12, conveying device; 13, pressure gauge; 14, pressure relief valve; 15, safety valve; 16, observation port; 17, bottom plate; 18, water storage tank; 19, additive tank; 20, cement bin; 21, steel slag bin. DETAILED DESCRIPTION

[0027] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0028] The first aspect of the present application proposes a system for fixing carbon dioxide by steel slag tailings, as shown in Figure 1 The system includes a carbon fixation reaction device 1, a mixing device 2, a brick making device 3 and a curing device 4; the top of the carbon fixation reaction device 1 is provided with a steel slag tailings inlet 5 and a water outlet 6, the bottom of the carbon fixation reaction device 1 has a gas inlet 7, the inside of the carbon fixation reaction device 1 is installed with a spraying device 8, and the side wall of the carbon fixation reaction device 1 is provided with a discharge port 9; the mixing device 2 is used to receive the carbon fixation steel slag from the discharge port 9, and mix the carbon fixation steel slag, water, cement and additives to obtain a mixture; the brick making device 3 is used to make the mixture obtained in the mixing device 2 into a permeable brick; the curing device 4 is used to make the permeable brick prepared in the brick making device 3 perform a carbon fixation reaction with carbon dioxide to obtain a steel slag permeable brick.

[0029] In the specific embodiment, the carbon fixation reaction device 1 is a closed rotary kiln. Specifically, the inside of the carbon fixation reaction device 1 is provided with a stirring device, and in the specific operation process, the stirring device inside the carbon fixation reaction device 1 is started at the same time as the carbon fixation reaction device 1 is started.

[0030] In the specific embodiment, the steel slag tailing inlet 5 in the carbon fixation reaction device 1 is in communication with the steel slag bin 21. Specifically, the steel slag tailing in the steel slag bin 21 is the remaining slag after the slag steel is removed by magnetic separation, and the content of metallic iron in the slag is <2%.

[0031] In the specific embodiment, the spraying device 8 is installed inside the carbon fixation reaction device 1, and specifically, the spraying device 8 has multiple nozzles, and the position of the spray head is close to the steel slag tailing inlet 5. At the same time, the conveying device 12 is started, and the conveying device 12 drives the rotating gear 11 to rotate the carbon fixation reaction device 1, so as to form a water film on the surface of the steel slag and promote more persistent and in-depth reaction of CaO, MgO, f-CaO, f-MgO, etc. in the steel slag with CO2.

[0032] In the specific embodiment, the top of the carbon fixation reaction device 1 is further provided with a pressure gauge 13, a pressure relief valve 14 and a safety valve 15. In the actual operation process, the carbon dioxide entering the carbon fixation reaction device 1 is reasonably controlled, so that the pressure in the carbon fixation reaction device 1 is limited within a certain range by observing the pressure gauge 13; after the reaction of the steel slag with CO2 is completed, the pressure relief valve 14 is needed to release the pressure in order to separate the steel slag from the water; the safety valve 15 is used to control the pressure in the carbon fixation reaction device 1 not to exceed the specified value, which protects the operation of the device.

[0033] In the specific embodiment, the top of the carbon fixation reaction device 1 is further provided with an observation port 16 for observing the reaction of the steel slag with CO2, so as to avoid incomplete reaction and thus poor carbon fixation effect.

[0034] In the specific embodiment, the carbon fixation reaction device 1 is placed on the bottom plate 17, the bottom plate 17 is at the same level as the mixing device 2, and the opening of the discharge port 9 is directly opposite the feed inlet of the mixing device 2. In the specific operation process, the carbon fixation steel slag discharged from the discharge port 9 is just input into the mixing device 2, so as to complete the mixing as soon as possible and improve the efficiency of the second carbon fixation reaction.

[0035] In the preferred embodiment, the bottom end of the carbon fixation reaction device 1 is sequentially provided with a plurality of supporting rollers 10 with gradually decreasing heights along the horizontal direction, and the height of the supporting roller 10 close to the discharge port 9 is the smallest. The supporting rollers 10 make the carbon fixation reaction device 1 in an inclined state, for example, the inclination angle of the carbon fixation reaction device 1 is 2-6°.

[0036] In a more preferred embodiment, a rotating gear 11 is fixed outside the shell of the carbon fixation reaction device 1, the rotating gear 11 is connected with a conveying device 12, the conveying device 12 drives the rotating gear 11 to rotate the carbon fixation reaction device 1. The carbon fixation reaction device 1 is stirred during rotation, the rotation time is ≥ 30 min, which promotes the more persistent and in-depth reaction of CaO, MgO, f-CaO, f-MgO, etc. in the steel slag with CO2, and promotes the removal and shedding of the water film on the surface of the steel slag and the solidified substances such as CaCO3 and MgCO3 generated by the reaction of the steel slag with CO2 on the surface of the steel slag.

[0037] In a specific embodiment, after the reaction is completed, the water outlet 6 is rotated to the bottom end, the pressure relief valve 14 is opened, and the filter screen is fixed on the water outlet 6, then the water is discharged from the water outlet 6, and the discharged water is collected into the water storage tank 18.

[0038] In a specific embodiment, the mixing device 2 includes a water storage tank 18, an additive tank 19, and a cement bin 20. In a specific operation process, the discharged carbon fixation steel slag enters the mixing device 2, and then the water storage tank 18, the additive tank 19, and the cement bin 20 respectively inject water, additives, and cement into the carbon fixation steel slag.

[0039] In a specific embodiment, the brick making device 3 uses a strong brick making machine with vibration function. In the preparation process of the permeable brick, the unreacted CaO, MgO, f-CaO, f-MgO, etc. in the steel slag further react with CO2 to improve the carbon fixation effect, and at the same time, the main minerals C3S and C2S in the cement react with CO2, and the cement hydration products Ca(OH)2 and CSH also react with CO2, which not only fixes carbon, but also quickly improves the strength of the cement, and the reaction in the preparation process of the permeable brick is as follows:

[0040] (1) 3CaO·SiO2+3CO2+yH2O→SiO2·yH2O+3CaCO3;

[0041] (2) 2CaO·SiO2+2CO2+yH2O→SiO2·yH2O+2CaCO3;

[0042] (3) Ca(OH)2+CO2→CaCO3+H2O;

[0043] (4) xCaO·ySiO2·zH2O+xCO2→xCaCO3+ySiO2·tH2O+(z-t)H2O.

[0044] In a specific embodiment, the curing device 4 is a closed structure to ensure that the introduced CO2 gas does not escape.

[0045] In actual operation, a certain amount of steel slag tailings in the steel slag bin 21 is introduced into the carbon fixation reaction device 1 through the steel slag tailings inlet 5, at the same time, the spraying device 8 is opened, the nozzles of the spraying device 8 are aimed at the steel slag tailings, and the amount of water sprayed by the spraying device 8 is controlled, at the same time, the conveying device 12 is started to drive the rotating gear 11 to make the carbon fixation reaction device 1 rotate, and the air inlet 7 is at the bottom of the carbon fixation reaction device 1, the conveying device 12 is closed, a certain amount of CO2 gas is introduced from the air inlet 7, then the carbon fixation reaction device 1 is sealed, and the introduction of CO2 gas is stopped until the pressure gauge 13 reaches a certain pressure value; the carbon fixation reaction device 1 and the internal stirring system are started, in the reaction process, the reaction of the steel slag and CO2 is observed through the observation port 16, until the reaction is completed, the water outlet 6 is rotated to the bottom end, the pressure relief valve 14 is opened, the filter screen is fixed at the water outlet 6, and the water is discharged from the water outlet 6, the carbon fixation steel slag obtained by the reaction is discharged from the discharge port 9 to the mixer; the water, the additive and the cement are respectively injected into the carbon fixation steel slag through the water storage tank 18, the additive tank 19 and the cement bin 20 in turn to obtain the mixed material, then the mixed material is introduced into the brick making device 3 to make bricks to obtain the permeable brick, finally, the permeable brick obtained is placed in the curing device 4, and CO2 is introduced into the curing device 4 to perform a second carbon fixation reaction to obtain the steel slag permeable brick.

[0046] The second aspect of the present application provides a method for fixing carbon dioxide by steel slag tailings, which is implemented in the system described above, and the method comprises the following steps:

[0047] S1, the steel slag tailings enter the carbon fixation reaction device 1 from the steel slag tailings inlet 5, water is sprayed into the carbon fixation reaction device 1 through the spraying device 8, carbon dioxide is introduced into the carbon fixation reaction device 1 through the air inlet 7, the steel slag tailings and the carbon dioxide perform a first carbon fixation reaction, after the reaction is completed, the water is discharged from the water outlet 6, and the carbon fixation steel slag produced by the reaction is discharged from the discharge port 9;

[0048] S2, the discharged carbon fixation steel slag enters the mixing device 2, and the carbon fixation steel slag, water, cement and additive are mixed in the mixing device 2 to obtain the mixed material;

[0049] S3, the obtained mixed material is input into the brick making device 3 to make bricks to obtain the permeable brick;

[0050] S4, the permeable brick is placed in the curing device 4, and carbon dioxide is introduced into the curing device 4 to make the permeable brick and the carbon dioxide perform a second carbon fixation reaction to obtain the steel slag permeable brick.

[0051] In a preferred embodiment, the mass ratio of the steel slag tailings to water is 1:5-10; carbon dioxide is introduced into the carbon fixation reaction device 1 through the gas inlet 7, so that the pressure in the carbon fixation reaction device 1 is 1-5 MPa. The reaction of CaO, MgO, f-CaO, f-MgO, etc. in the steel slag with CO2 can be promoted to be more persistent and in-depth, and the carbon fixation effect can be improved.

[0052] In a preferred embodiment, the mass ratio of the carbon fixation steel slag, cement, water and additive is 3.5-8:1:0.2-0.4:0.01-0.04, and specifically, the water value in the ratio includes the water content of the steel slag.

[0053] In a specific embodiment, the cement can be ordinary Portland cement and / or slag Portland cement.

[0054] In a preferred embodiment, the additive includes but is not limited to a water reducing agent; the water reducing agent is one or two or more of isobutylene polyoxyethylene ether, isoamylene polyoxyethylene ether and methyl methacrylate.

[0055] In a preferred embodiment, carbon dioxide with a concentration of ≥20% is introduced into the curing device 4.

[0056] In a specific embodiment, when the water permeable bricks are cured in the curing device 4, the spacing distance of each brick is ≥20 mm.

[0057] In a preferred embodiment, the conditions of the second carbon fixation reaction include a temperature of 18-22℃, a humidity of 40-90%, and a time of 25-30 days.

[0058] In the following examples, the test methods or test methods are conventional methods unless otherwise specified; the reagents and materials are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0059] A system for fixing carbon dioxide by using steel slag tailings, comprising a carbon fixation reaction device 1, a curing device 4 and a carbon fixation product output device 5, wherein Figure 1As shown, the system comprises a carbon fixation reaction device 1, a mixing device 2, a brick making device 3 and a curing device 4; the top of the carbon fixation reaction device 1 is provided with a steel slag tail slag inlet 5, a water outlet 6, a pressure gauge 13, a pressure relief valve 14, a safety valve 15 and an observation port 16, the bottom of the carbon fixation reaction device 1 has an air inlet 7, the inside of the carbon fixation reaction device 1 is installed with a spraying device 8, the side wall of the carbon fixation reaction device 1 is provided with a discharge port 9, the bottom end of the carbon fixation reaction device 1 is sequentially installed with a plurality of supporting wheels 10 with gradually decreasing heights along the horizontal direction, and the height of the supporting wheel 10 close to the discharge port 9 is the smallest, the supporting wheels 10 make the carbon fixation reaction device 1 in an inclined state with an inclination angle of 6°, the outside of the shell of the carbon fixation reaction device 1 is fixed with a rotating gear 11, the rotating gear 11 is connected with a conveying device 12, the conveying device 12 can drive the rotating gear 11 to rotate the carbon fixation reaction device 1; the mixing device 2 is used for receiving the carbon fixation steel slag from the discharge port 9, the mixing device 2 comprises a water storage tank 18, an additive tank 19 and a cement bin 20, the mixing device 2 mixes the carbon fixation steel slag, water, cement and additives to obtain a mixture.

[0060] The following steel slag tail slag is from the steel slag of a certain steel plant, after the slag steel is removed by magnetic separation, the remaining slag contains <2% of metallic iron.

[0061] Example 1

[0062] The present embodiment provides a method for fixing carbon dioxide by steel slag tail slag, the method flow is as shown in the figure Figure 2 The method comprises the following steps:

[0063] S1, the steel slag tail slag enters the carbon fixation reaction device 1 from the steel slag tail slag inlet 5, water is sprayed into the carbon fixation reaction device 1 through the spraying device 8, the mass ratio of steel slag tail slag to water is 1:7, the conveying device 12 is started to rotate the carbon fixation reaction device 1 for about 3 rounds, and the air inlet 7 is at the bottom of the carbon fixation reaction device 1, the conveying device 12 is closed, carbon dioxide is introduced into the carbon fixation reaction device 1 through the air inlet 7, and the value of the pressure gauge 13 reaches 2MPa; the air inlet 7 is closed, then the carbon fixation reaction device 1 and the internal stirring system are started, the steel slag tail slag and the carbon dioxide are subjected to the first carbon fixation reaction, the reaction is completed after 60min, the carbon fixation reaction device 1 is closed, a filter screen is placed at the water outlet 6, the conveying device 12 is started to rotate and discharge the water from the water outlet 6, the discharged water is collected into the water storage tank, and the carbon fixation steel slag produced by the reaction is discharged from the discharge port 9;

[0064] S2, the discharged carbon fixation steel slag enters the mixing device 2, and the carbon fixation steel slag, water, ordinary Portland cement and isoamylene polyoxyethylene ether (water reducing agent) are mixed in the mixing device 2, the mass ratio of the carbon fixation steel slag, water, ordinary Portland cement and isoamylene polyoxyethylene ether is 3.5:1:0.2:0.01, and a mixture is obtained;

[0065] S3, the obtained mixture is input into the brick making device 3 to make bricks, and the water permeable bricks are obtained;

[0066] S4, the steel slag water permeable bricks are placed in the curing device 4 with a temperature of 20 DEG C and a humidity of 80%, and carbon dioxide gas with a concentration of 50% is introduced into the curing device 4, the curing device 4 is in a closed state, the steel slag water permeable bricks are subjected to a second carbon fixation reaction with carbon dioxide, and the steel slag water permeable bricks are obtained after 28 days.

[0067] Example 2

[0068] The embodiment provides a method for fixing carbon dioxide by using steel slag tailings, and the method comprises the following steps:

[0069] S1, the steel slag tailings enter the carbon fixation reaction device 1 from the steel slag tailings inlet 5, water is sprayed into the carbon fixation reaction device 1 through the spraying device 8, the mass ratio of the steel slag tailings to water is 1:5, the conveying device 12 is started to rotate the carbon fixation reaction device 1 for about 5 rounds, and the gas inlet 7 is located at the bottom of the carbon fixation reaction device 1, the conveying device 12 is closed, carbon dioxide is introduced into the carbon fixation reaction device 1 through the gas inlet 7, the value of the pressure gauge 13 reaches 2 MPa, the gas inlet 7 is closed, and then the carbon fixation reaction device 1 and the internal stirring system are started, the steel slag tailings and carbon dioxide are subjected to a first carbon fixation reaction, the reaction is completed after 60 min, the carbon fixation reaction device 1 is closed, the filter screen is placed in the water outlet 6, the conveying device 12 is started to rotate and discharge water from the water outlet 6, the discharged water is collected into the water storage tank, and the carbon fixation steel slag generated in the reaction is discharged from the discharge outlet 9;

[0070] S2, the discharged carbon fixation steel slag enters the mixing device 2, and the carbon fixation steel slag, water, ordinary Portland cement and isoamylene polyoxyethylene ether are mixed in the mixing device 2, the mass ratio of the carbon fixation steel slag, water, ordinary Portland cement and isoamylene polyoxyethylene ether is 3.5:1:0.2:0.01, and a mixture is obtained;

[0071] S3, the obtained mixture is input into the brick making device 3 to make bricks, and the water permeable bricks are obtained;

[0072] S4, the steel slag water permeable brick is placed in a curing device 4 with a temperature of 20℃ and a humidity of 55%, and carbon dioxide gas with a concentration of 80% is introduced into the curing device 4, the curing device 4 is in a closed state, the steel slag water permeable brick is subjected to a second carbon fixation reaction with carbon dioxide, and the steel slag water permeable brick is obtained after 28 days.

[0073] Example 3

[0074] The present embodiment provides a method for fixing carbon dioxide by steel slag tailings, which comprises the following steps:

[0075] S1, the steel slag tailings enter the carbon fixation reaction device 1 from the steel slag tailings inlet 5, water is sprayed into the carbon fixation reaction device 1 through the spraying device 8, the mass ratio of steel slag tailings to water is 1:10, the transmission device 12 is started to rotate the carbon fixation reaction device 1 for about 6 rounds, and the air inlet 7 is at the bottom of the carbon fixation reaction device 1, the transmission device 12 is closed, carbon dioxide is introduced into the carbon fixation reaction device 1 through the air inlet 7, and the value of the pressure gauge 13 reaches 5MPa; the air inlet 7 is closed, and then the carbon fixation reaction device 1 and the internal stirring system are started, the steel slag tailings and carbon dioxide are subjected to a first carbon fixation reaction, the reaction is completed after 90min, the carbon fixation reaction device 1 is closed, a filter screen is placed in the water outlet 6, the transmission device 12 is started to rotate and discharge water from the water outlet 6, the discharged water is collected in a water storage tank, and the carbon fixation steel slag produced in the reaction is discharged from the discharge outlet 9;

[0076] S2, the discharged carbon fixation steel slag enters the mixing device 2, the carbon fixation steel slag, water, ordinary portland cement and methyl methacrylate are mixed in the mixing device 2, the mass ratio of the carbon fixation steel slag, water, ordinary portland cement and methyl methacrylate is 7:1:0.2:0.04, and the mixture is obtained;

[0077] S3, the obtained mixture is input into the brick making device 3 to make bricks, and the steel slag water permeable brick is obtained;

[0078] S4, the steel slag water permeable brick is placed in a curing device 4 with a temperature of 20℃ and a humidity of 40%, and carbon dioxide gas with a concentration of 100% is introduced into the curing device 4, the curing device 4 is in a closed state, the steel slag water permeable brick is subjected to a second carbon fixation reaction with carbon dioxide, and the steel slag water permeable brick is obtained after 28 days.

[0079] Comparative Example 1

[0080] According to the manner of Example 1, the difference is that in step S4, no carbon dioxide is introduced into the curing device 4 for the second carbon fixation reaction.

[0081] Test Example

[0082] The carbonation conversion rate of the steel slag, the free calcium oxide content of the steel slag and the compressive strength of the steel slag permeable brick of the steel slag tailings treated by the method for fixing carbon dioxide of the steel slag tailings of examples 1-3 and comparative example 1 were detected, the detection method of the free calcium oxide content of the steel slag was carried out according to the standard YB / T4328 steel slag free calcium oxide content determination method, the detection method of the compressive strength of the steel slag permeable brick was carried out according to the standard JC / T permeable brick appendix A compressive strength test method, and the detection results are shown in table 1.

[0083] Table 1 detection results of the method treated by examples 1-3 and comparative example 1

[0084]

[0085] It can be seen from the results in table 1 that compared with not using the permeable brick for the second carbon fixation reaction, the method used in the present application can realize the fixation of carbon dioxide by full particle size steel slag tailings, improve the full utilization of resources after stability, solve the problem that the utilization range of the steel slag tailings is limited by the improvement of the carbon fixation effect by fine, at the same time, the carbonation conversion rate of the steel slag can be greater than 80%, the free calcium oxide content in the steel slag after carbon fixation is reduced to below 0.5%, and the compressive strength of the steel slag permeable brick is increased by 50-200%.

[0086] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the present application, and all belong to the protection scope of the present application.

Claims

1. A system for fixing carbon dioxide in steel slag tailings, characterized in that, The system includes a carbon fixation reaction device (1), a mixing device (2), a brick making device (3), and a curing device (4); the top of the carbon fixation reaction device (1) is provided with a steel slag tailings inlet (5) and a water outlet (6), the bottom of the carbon fixation reaction device (1) has an air inlet (7), the interior of the carbon fixation reaction device (1) is equipped with a spraying device (8), and the side wall of the carbon fixation reaction device (1) is provided with a discharge outlet (9); The carbon fixation reaction device (1) is a closed rotary kiln used for the first carbon fixation reaction of steel slag tailings of all particle sizes. Several rollers (10) with gradually decreasing height are installed at the bottom of the carbon fixation reaction device (1) along the horizontal direction, and the rollers (10) near the discharge port (9) have the smallest height. The rollers (10) make the carbon fixation reaction device (1) tilted. A rotating gear (11) is fixed outside the shell of the carbon fixation reaction device (1). The rotating gear (11) is connected to a conveying device (12). The conveying device (12) drives the rotating gear (11) to rotate the carbon fixation reaction device (1). Water is sprayed into the carbon fixation reaction device (1) through a spraying device (8) to control the mass ratio of steel slag tailings to water to be 1:5-10. Carbon dioxide is introduced into the carbon fixation reaction device (1) through an air inlet (7) to control the pressure inside the carbon fixation reaction device (1) to be 1-5 MPa. The mixing device (2) is used to receive the carbonized steel slag after the first carbonization reaction from the discharge port (9), and to mix the carbonized steel slag, water, cement and admixtures in a mass ratio of 3.5-8:1:0.2-0.4:0.01-0.04 to obtain a mixture; The brick-making device (3) is used to make permeable bricks from the mixture obtained in the mixing device (2); The curing device (4) is a closed structure used to carry out a second carbon fixation reaction between the permeable bricks prepared in the brick-making device (3) and carbon dioxide: a concentration of ≥20% carbon dioxide is introduced into the curing device (4) and carried out for 25-30 days at a temperature of 18-22℃ and a humidity of 40-90% to obtain steel slag permeable bricks.

2. The system for fixing carbon dioxide in steel slag tailings according to claim 1, characterized in that, The top of the carbon fixation reactor (1) is also equipped with a pressure gauge (13), a pressure relief valve (14), and a safety valve (15).

3. A method for fixing carbon dioxide in steel slag tailings, wherein the method is implemented in the system described in any one of claims 1-2, characterized in that, The method includes the following steps: S1. Steel slag tailings enter the carbon fixation reaction device (1) through the steel slag tailings inlet (5). Water is sprayed into the carbon fixation reaction device (1) through the spray device (8). Carbon dioxide is introduced into the carbon fixation reaction device (1) through the air inlet (7). The steel slag tailings and carbon dioxide undergo the first carbon fixation reaction. After the reaction is completed, water is discharged from the water outlet (6), and the carbon-fixed steel slag produced by the reaction is discharged from the discharge outlet (9). S2. The discharged solid carbon steel slag enters the mixing device (2), where the solid carbon steel slag, water, cement and additives are mixed to obtain a mixture. S3. The obtained mixture is fed into the brick-making device (3) to make bricks, and permeable bricks are obtained. S4. Place the permeable brick in the curing device (4) and simultaneously introduce carbon dioxide into the curing device (4) to allow the permeable brick to undergo a second carbon fixation reaction with the carbon dioxide, thereby obtaining steel slag permeable brick.

4. The method for fixing carbon dioxide in steel slag tailings according to claim 3, characterized in that, The admixture includes a water-reducing agent; The water-reducing agent is one or more of isobutylene polyoxyethylene ether, isopentenene polyoxyethylene ether, and methyl methacrylate.

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