A system and method for preparing high-activity SCM materials from low-carbon raw materials

Abstract

The present invention discloses a system and method for preparing high-activity SCM materials from low-carbon raw materials, comprising a cement burning system, a clinker grinding system, a low-pressure suspended carbonization bed system, a bag dust collector, and an induced draft fan; the material outlet of the grate cooler is connected to the material inlet of the clinker grinding system, the flue gas outlet of the kiln tail preheating and predecomposition system is connected to the flue gas inlet of the clinker grinding system, and the flue gas outlet of the kiln tail preheating and predecomposition system is connected to the flue gas inlet of the low-pressure suspended carbonization bed system through a dust collector, and the material inlet is provided on the low-pressure suspended carbonization bed system. Clean flue gas and an aqueous solution are sprayed into the suspended carbonization bed, forming a liquid film on the surface of the material. CO2 in the clean flue gas dissolves in the liquid film and reacts with the material to form a carbonization reaction. The powder collected by the bag dust collector can be returned to the low-pressure suspended carbonization bed system for cyclic carbonization, and a high-activity SCM material can also be directly obtained. The present invention reduces carbon emissions, improves the carbonization rate, and improves the activity of the prepared SCM material.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon emission reduction, and in particular to a system and method for preparing high-activity SCM materials from low-carbon raw materials. Background Art

[0002] Cement production consumes a large amount of natural resources and emits a large amount of carbon dioxide. The cement industry is the third largest source of carbon dioxide emissions in my country, accounting for about 13% of the country's total industrial carbon emissions. In 2022, my country's cement production reached 2.118 billion tons, and carbon dioxide emissions were about 1.3 billion tons. Therefore, carbon emission reduction in the domestic cement industry is related to the realization of the strategic goals of carbon peak and carbon neutrality. To this end, academia and industry have proposed and adopted various energy-saving and emission-reduction strategies, such as reducing the amount of cement in concrete, lowering the clinker coefficient in cement, reducing carbon emissions in the cement clinker production process, using new biomass fuels, and carbon capture, utilization and storage.

[0003] Current general-purpose cement is primarily ordinary Portland cement, whose primary mineral components include C3S, C2S, C3A, and C4AF. It is produced by a hydration reaction with water and mixing to form a cementitious material. Ordinary Portland cement is primarily made from limestone. Producing one ton of ordinary Portland cement clinker consumes approximately 1.2 tons of limestone, generating approximately 500 kg of CO2 emissions, accounting for approximately 60% of the total carbon emissions from cement production. To reduce carbon emissions from cement production, developing new carbonizable low-calcium, low-carbon cement varieties is an important approach. This not only reduces calcium carbonate raw material consumption but also captures some CO2 during the cement carbonization process. However, the primary application of carbonizable low-carbon cement in the concrete products industry has severely limited its widespread adoption. Therefore, if new carbonizable low-carbon clinker could be prepared into a highly active auxiliary cementing material and used in cement and concrete, resulting in carbon-negative cement and concrete, the application scope of this new carbonizable low-carbon cement would be expanded, potentially becoming an effective path to reducing carbon emissions in the cement industry.

[0004] At present, most of the reports on carbonizable low-calcium and low-carbon cement are still in the laboratory research stage. In the Low-CO2 synthetic SCMs published in the International Cement Review magazine by Solida Technologies, USA, it is mentioned that low-carbon clinker mainly composed of carbonizable minerals is used to introduce industrial tail gas containing carbon dioxide into the slurry or semi-wet state to prepare SCM materials. The low-carbon clinker used is mainly CS and C3S2. These two minerals basically do not react with water for hydration, but can react with carbon dioxide to form calcite and amorphous silica. Solida's literature mentioned that the SCM it prepared contains a large amount of calcite products. However, the GB175-2021 "General Portland Cement" standard has clear requirements for cement loss on ignition. If the SCM content is 30%, sufficient carbonization can form about 15% calcite. Since PⅡ type silicate cement requires limestone content ≤5%, silicate cement (PI and PⅡ) requires loss on ignition less than 3.0% and 3.5% respectively, and ordinary silicate cement requires PO loss on ignition ≤5.0%, and the GB / T1596-2017 "Fly ash in cement and concrete" standard requires loss on ignition as an admixture ≤8.0%, this seriously limits the range of content of SCM materials prepared after full carbonization.

[0005] Low-carbon cement has broad application prospects in the field of carbon emission reduction. There are no reports on industrial-grade carbonization methods and carbonization systems for low-carbon cement. At present, relatively more research is on the carbonization of steel slag. Chinese Patent Publication No. CN113072311A discloses a steel slag auxiliary cementitious material and its preparation method and application. It mentions the use of industrial tail gas for carbonizing steel slag powder, and the introduction of industrial tail gas containing a carbon dioxide concentration of 20% during the grinding process. However, due to the limited volume of the grinding equipment, the residence time of the flue gas in the mill is relatively short. It is difficult to fully carbonize the steel slag by only carbonization reaction inside the mill, and the carbonization process is uncontrollable. Chinese Patent Publication No. CN214571715U discloses a heating and pressurizing device for carbonizing steel slag with tailings soil test blocks. By controlling the temperature and carbon dioxide gas pressure, the carbonization rate is significantly improved, which greatly accelerates the reaction process and improves the comprehensive utilization of steel slag and carbon dioxide. However, since the pressurization system is limited by the volume of the pressure vessel and the feeding method, this pressurized carbonization method is difficult to scale up industrially and is difficult to produce continuously.

[0006] In summary, the problems existing in the prior art are:

[0007] (1) Calcium carbonate accounts for a large proportion of the commonly used cement raw materials, and the production process generates a large amount of carbon emissions.

[0008] (2) Low-calcium low-carbon cement can reduce the proportion of carbonates and reduce carbon emissions, but if it is not carbonized to increase its activity, its application range will be relatively narrow.

[0009] (3) The existing pressurized carbonization method is difficult to meet the needs of large-scale production and continuous operation of the production process.

[0010] (4) The existing in-mill carbonization method has a short reaction residence time, incomplete carbonization reaction, uncontrollable carbonization process, low activity of the carbonized material, and cannot fully capture flue gas CO2.

[0011] Therefore, under the global carbon emission reduction situation, there is an urgent need to develop a new process method suitable for industrial-scale continuous production, with low raw material carbon emissions, high carbonization rate, and high activity of SCM materials after carbonization. Summary of the Invention

[0012] In order to solve the problems existing in the prior art, the present invention provides a system and method for preparing high-activity SCM materials from low-carbon raw materials, which reduces the consumption of raw material carbonate and captures flue gas CO2, thereby reducing carbon emissions.

[0013] The present invention is achieved as follows: a system for preparing high-activity SCM materials from low-carbon raw materials, including a cement burning system, a clinker grinding system, a low-pressure suspended carbonization bed system, a bag dust collector and an induced draft fan;

[0014] The cement burning system includes a kiln tail preheating and precalcining system, a rotary kiln, and a grate cooler connected in sequence; the material outlet of the grate cooler is connected to the material inlet of the clinker grinding system, the kiln tail flue gas outlet of the kiln tail preheating and precalcining system is connected to the flue gas inlet of the clinker grinding system, and the powdered material outlet of the clinker grinding system is connected to the material inlet of the low-pressure suspended carbonization bed system;

[0015] The low-pressure suspended carbonization bed system includes an air duct, a suspended carbonization bed and a water spray system. The air duct is located below the suspended carbonization bed, and the bottom of the air duct is a flue gas inlet. The kiln tail flue gas outlet of the kiln tail preheating and predecomposition system is connected to the flue gas inlet of the air duct through a dust collector. The material inlet of the low-pressure suspended carbonization bed system is arranged in the air duct or the suspended carbonization bed, so that the powdered material moves upward under the drive of the flue gas. The top of the air duct is connected to the bottom of the suspended carbonization bed, and a spray pipe is provided at the connection part, so that the clean flue gas after the dust removal from the kiln tail preheating and predecomposition system is sprayed upward into the suspended carbonization bed; a plurality of spray guns are provided at the lower part of the suspended carbonization bed and are located above the spray pipe. The outlet of the water spray system is connected to the spray gun inlet, so that the aqueous solution is sprayed into the suspended carbonization bed in the form of droplets. The water vapor in the flue gas in the suspended carbonization bed forms a critical saturation state of water vapor-water droplets, and a liquid film is formed on the surface of the material;

[0016] The outlet of the suspended carbonization bed is connected to the flue gas inlet of the bag dust collector; the material outlet of the bag dust collector is connected to the high-activity SCM material finished product, or is respectively connected to the high-activity SCM material finished product and the material inlet of the low-pressure suspended carbonization bed system, and the flue gas outlet of the bag dust collector is connected to the induced draft fan inlet.

[0017] In the above technical solution, preferably, the suspended carbonization bed includes a sparging pipe, a carbonization bed cone, and a carbonization bed column connected sequentially from bottom to top; the sparging pipe is a vertical pipe, and a guide device for evenly distributing the flue gas is provided inside the sparging pipe. The guide device is a guide plate, a grille, or a guide ring.

[0018] In the above technical solution, it is further preferred that an ultrasonic generator is provided at the vertebral body of the carbonization bed.

[0019] In the above technical solution, preferably, a secondary temperature-controlled mixing chamber is provided between the suspended carbonization bed and the bag dust collector, and the secondary temperature-controlled mixing chamber is used to increase the temperature of the flue gas exiting the suspended carbonization bed and reduce the humidity of the flue gas; the secondary temperature-controlled mixing chamber has inlet one, inlet two and an outlet, the top outlet of the suspended carbonization bed is connected to inlet one of the secondary temperature-controlled mixing chamber, the kiln tail flue gas outlet of the kiln tail preheating and predecomposition system is connected to inlet two of the secondary temperature-controlled mixing chamber through the dust collector, and the outlet of the secondary temperature-controlled mixing chamber is connected to the flue gas inlet of the bag dust collector.

[0020] In the above technical solution, it is further preferred that a temperature measuring device is provided on the outlet pipe of the secondary temperature-controlled mixing chamber.

[0021] In the above technical solution, it is further preferred that a powder selection and separation device is arranged between the secondary temperature-controlled mixing chamber and the bag dust collector, the outlet of the secondary temperature-controlled mixing chamber is connected to the flue gas inlet of the powder selection and separation device, the bottom material outlet of the powder selection and separation device is connected to the material inlet of the low-pressure suspended carbonization bed system, and the top flue gas outlet of the powder selection and separation device is connected to the flue gas inlet of the bag dust collector.

[0022] In the above technical solution, it is further preferred that the powder selection and separation device is a powder selector or a cyclone, which is used to separate coarse powder and fine powder in the material.

[0023] In the above technical solution, it is further preferred that an air lock valve and a material distribution valve are sequentially provided on the material pipe at the bottom material outlet of the powder selection and separation device, and the bottom material outlet of the powder selection and separation device is also connected to the high-activity SCM material finished product through the material distribution valve, so that the coarse powder exiting the powder selection and separation device can enter the suspended carbonization bed and the high-activity SCM material finished product respectively.

[0024] In the above technical solution, preferably, a vertically placed filter bag is provided in the bag dust collector, and a compressed air blowing device for regularly cleaning powder cakes on the surface of the filter bag is also provided in the bag dust collector.

[0025] A method for preparing a high-activity SCM material from a low-carbon raw material comprises the following steps:

[0026] S1. Raw material batching and clinker burning

[0027] Siliceous raw materials, calcium raw materials, gypsum and mineralizers are ground into raw materials in a certain proportion. The raw materials are then preheated and decomposed in the kiln tail preheating and predecomposition system and then sent to the rotary kiln for calcination. The calcination temperature in the rotary kiln is 1100-1300℃. The calcined clinker is sent to the grate cooler for cooling to obtain low-carbon cement clinker.

[0028] S2. Clinker grinding

[0029] The low-carbon cement clinker particles are transported to the clinker grinding system, and the flue gas from the kiln preheating and predecomposition system is introduced into the clinker grinding system. The flue gas from the kiln preheating and predecomposition system contains 25% to 35% CO2 in concentration, which is ground into low-carbon cement clinker powder. The average particle size of the low-carbon cement clinker powder is less than 200μm.

[0030] S3. Carbonization to prepare highly active SCM materials

[0031] Suspension carbonization:

[0032] The clean flue gas after the preheating and pre-decomposition system at the kiln tail and the dust removal is introduced into the flue gas inlet of the air duct. The clean flue gas after the preheating and pre-decomposition system at the kiln tail and the dust removal has a temperature of 100-150°C and a CO2 concentration of 25%-35%. The clean flue gas moves upward and is sprayed into the suspended carbonization bed through the spray pipe. At the same time, low-carbon cement clinker powder with a temperature of ≤60°C and an average particle size of less than 200μm is dispersed and fed into the air duct or the suspended carbonization bed, so that the material is suspended in the clean flue gas under the action of air flow drag. The pressure in the suspended carbonization bed is 0-3000Pa, and the average wind speed in the cross section of the suspended carbonization bed is 3-10m / s. At the same time, water or a carbonization aid aqueous solution is sprayed into the suspended carbonization bed in the form of droplets through a spray gun, so that the water vapor in the flue gas reaches a critical saturation state. The water vapor forms a liquid film on the surface of the material, and the CO2 in the flue gas dissolves in the liquid film to react with the material to form a carbonization reaction.

[0033] Coarse powder circulation and finished product collection:

[0034] The flue gas from the suspended carbonization bed carries the material and enters the bag dust collector under the draft of the induced draft fan. After the material is collected, part of it returns to the low-pressure suspended carbonization bed system for circulating carbonization, and part of it is led to the high-activity SCM material finished product; or, all of it is led to the high-activity SCM material finished product.

[0035] In the above technical solution, preferably, the content of SiO2 in the siliceous raw material is ≥50%, the content of CaO in the calcareous raw material is ≥35%, the gypsum is one of desulfurized gypsum, phosphogypsum, and natural gypsum, and the mineralizer is one of fluorite, calcium fluoride, borax, and boric acid, or a combination of any two of them.

[0036] In the above technical solution, preferably, the mineral composition of the low carbon cement clinker includes: α′-C2S, C4A3$, C5S2$, CS, β-C2S, wherein the sum of the contents of α′-C2S and β-C2S accounts for more than 40% of the total mass of the low carbon cement clinker, the sum of the contents of C4A3$ and C5S2$ accounts for more than 20% of the total mass of the low carbon cement clinker, the content of CS accounts for more than 20% of the total mass of the low carbon cement clinker, and the rest is glass phase.

[0037] In the above technical solution, preferably, during the suspension carbonization process, ultrasonic vibration is added to the bottom of the suspension carbonization bed.

[0038] In the above technical solution, preferably, in the carbonization aid aqueous solution, the carbonization aid is one or a combination of any two of lignin sulfonates, polycyclic aromatic salts, water-soluble resin sulfonates, and alcohol-ammonia organic compounds.

[0039] In the above technical solution, preferably, the flue gas carrying the material out of the suspended carbonization bed first enters the secondary temperature-controlled mixing chamber and is mixed with part of the clean flue gas out of the kiln tail preheating and predecomposition system and after dust removal, and then enters the powder selection and separation device; the flue gas temperature out of the secondary temperature-controlled mixing chamber is controlled at 70-100°C.

[0040] In the above technical solution, it is further preferred that the flue gas carrying the material out of the secondary temperature-controlled mixing chamber first enters the powder selection and separation device, and the coarse powder in the material is collected and discharged from the bottom of the powder selection and separation device, part of which is returned to the low-pressure suspended carbonization bed system for cyclic carbonization, and part is led to the high-activity SCM material finished product; the fine powder is discharged from the top of the powder selection and separation device with the flue gas and enters the bag dust collector, and the flue gas passes through the filter bag with a filtration wind speed of 0.5 to 1.5 m / min, so that the fine powder forms a powder cake on the surface of the filter bag. The CO2 in the flue gas continues to carbonize with the material during the process of passing through the powder cake, and the compressed air is regularly purged to clean the powder cake. The powder collected from the bag dust collector is carbonized micropowder material, which is led to the high-activity SCM material finished product.

[0041] The advantages and positive effects of the present invention are:

[0042] (1) The present invention sets up a low-pressure suspended carbonization bed system, realizes the fluidized mixing of gas and solid in the suspended carbonization bed, and improves the carbonization reaction rate. The low-pressure working environment in the suspended carbonization bed creates conditions for continuous production. The carbonization aid aqueous solution is sprayed into the suspended carbonization bed and then dispersed and attached to the particle surface in the form of droplets to form a liquid film. The liquid film serves as a gas-solid mass transfer bridge for the carbonization reaction, which can accelerate the carbonization rate. At the same time, water or a carbonization aid aqueous solution with a crystal form control agent is sprayed into the suspended carbonization bed, which promotes the full coverage of the particle surface by water or the crystal form control agent, reduces the formation of calcite, increases amorphous calcium carbonate, and improves the activity of the SCM material.

[0043] (2) The present invention solves the problem of condensation caused by dew point drop of flue gas exiting the suspended carbonization bed due to water spraying or carbonization aid aqueous solution during carbonization by introducing a preheating and predecomposition system at the kiln tail of the cement burning system and performing secondary temperature control on the flue gas at the kiln tail after dust removal, thereby increasing the amount of water sprayed in the suspended carbonization bed and facilitating further carbonization; and simultaneously increasing the CO2 concentration by introducing a preheating and predecomposition system at the kiln tail of the cement burning system and performing secondary temperature control on the flue gas at the kiln tail after dust removal, thereby facilitating carbonization along the subsequent pipeline and bag dust collector; and causing fine powder to adhere to the surface of the filter bag when dust is collected by the bag dust collector, and the fine powder can continue to be carbonized during the process of CO2 gas penetrating the filter bag.

[0044] (3) A portion of the flue gas discharged from the cement burning system of the present invention directly enters the clinker grinding system, and the other portion of the flue gas is divided into two streams after dust removal, one of which is sprayed into the low-pressure suspended carbonization bed system, and the other enters the secondary temperature-controlled mixing chamber. This can fully capture the CO2 in the flue gas and reduce the carbon emissions of the burning system.

[0045] (4) An ultrasonic generator is provided at the bottom of the suspended carbonization bed of the present invention, which reduces particle agglomeration through high-frequency acoustic vibration, thus facilitating a series of subsequent operations.

[0046] (5) The present invention returns the coarse powder to the low-pressure suspended carbonization bed system through the powder selection and separation process, thereby avoiding the problems of small specific surface area and low carbonization degree of the coarse powder, realizing cyclic carbonization, and improving the carbonization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of a system for preparing highly active SCM materials from low-carbon raw materials provided in Example 1 of the present invention;

[0048] Figure 2 This is a process flow chart for preparing highly active SCM materials from low-carbon raw materials provided in Example 1 of the present invention;

[0049] Figure 3 Schematic diagram of the positional relationship of the three phases of low carbon cement clinker, liquid film and flue gas in the suspended carbonization bed of the present invention;

[0050] Figure 4 Schematic diagram of a system for preparing highly active SCM materials from low-carbon raw materials provided in Example 2 of the present invention;

[0051] Figure 5 This is a process flow chart for preparing highly active SCM materials from low-carbon raw materials provided in Example 2 of the present invention.

[0052] In the figure: Q1 - clean flue gas from the air inlet pipe; Q2 - low CO2 flue gas; Q3 - clean flue gas entering the secondary temperature-controlled mixing chamber; Q4 - kiln tail flue gas entering the clinker grinding system; M1 - low-carbon cement clinker powder; M2 - first-stage finished product; M3 - recycled material from the bag dust collector; M4 - recycled material from the powder separation device; M5 - second-stage finished product; M6 - combined finished product; R1 - raw meal entering the preheater; K - low-carbon cement clinker particles; F - fuel; A - material particles; B - liquid film; C - flue gas;

[0053] 1-Cement burning system; 101-Preheater; 102-Precalciner; 103-Rotary kiln; 104-Grate cooler; 105-Burner; 106-High-temperature fan; 107-Dust collector; 108-Exhaust fan;

[0054] 2-Clinker grinding system;

[0055] 3- low-pressure suspended carbonization bed system; 301- spray pipe; 302- carbonization bed cone; 303- carbonization bed column; 304- ultrasonic generator; 305- water spray system; 306- spray gun; 307- air duct;

[0056] 4-bag dust collector; 401-filter bag;

[0057] 5- induced draft fan;

[0058] 6-secondary temperature-controlled mixing chamber; 601-temperature measuring device;

[0059] 7-powder selection and separation device; 701-air lock valve; 702-material distribution valve;

[0060] The dashed line with arrows is the direction of air flow; the solid line with arrows is the direction of material flow. DETAILED DESCRIPTION

[0061] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0062] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0063] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0064] Example 1

[0065] See also Figure 1 and Figure 2 An embodiment of the present invention provides a system for preparing high-activity SCM materials from low-carbon raw materials, including a cement burning system 1, a clinker grinding system 2, a low-pressure suspended carbonization bed system 3, a bag dust collector 4 and an induced draft fan 5.

[0066] The cement burning system 1 includes a kiln tail preheating and predecomposition system, a rotary kiln 103 and a grate cooler 104 connected in sequence. The kiln tail preheating and predecomposition system includes a preheater 101 and a decomposition furnace 102; the material outlet of the grate cooler 104 is connected to the material inlet of the clinker grinding system 2, the kiln tail flue gas outlet of the kiln tail preheating and predecomposition system is connected to the flue gas inlet of the clinker grinding system 2, and the powdered material outlet of the clinker grinding system 2 is connected to the material inlet of the low-pressure suspended carbonization bed system 3.

[0067] The low-pressure suspended carbonization bed system 3 includes an air duct 307, a suspended carbonization bed and a water spraying system 305. The air duct 307 is located below the suspended carbonization bed. The bottom of the air duct 307 is a flue gas inlet. The flue gas outlet of the kiln tail preheating and predecomposition system is connected to the flue gas inlet of the air duct 307 through the dust collector 107. The material inlet of the low-pressure suspended carbonization bed system 3 is set in the air duct 307 or the suspended carbonization bed. In this embodiment, a material inlet is set on the air duct 307 to allow the low-carbon cement clinker powder M1 to move upward under the influence of the flue gas; the top of the air duct 307 is connected to the bottom of the suspended carbonization bed, and a spraying pipe 301 is set at the connection part to allow the clean flue gas exiting the kiln tail preheating and predecomposition system and after dust removal to be sprayed upward into the suspended carbonization bed.

[0068] A plurality of spray guns 306 are provided at the lower part of the suspended carbonization bed and are located above the spray pipe 301. The outlet of the water spray system 305 is connected to the inlet of the spray gun 306, so that the aqueous solution is sprayed into the suspended carbonization bed in the form of droplets. The water vapor in the flue gas in the suspended carbonization bed forms a water vapor-water droplet critical saturation state, and a liquid film B is formed on the surface of the material particles A. Figure 3 shown.

[0069] The outlet of the suspended carbonization bed is connected to the flue gas inlet of the bag filter 4. The material outlet of the bag filter 4 is divided into two paths: one path is connected to the finished product of the highly active SCM material, and the other path is connected to the air duct 307 or the material inlet of the suspended carbonization bed, returning the collected material to the air duct 307 or the suspended carbonization bed. In this embodiment, the material outlet of the bag filter 4 is also connected to the material inlet of the air duct 307, returning part of the material collected by the bag filter to the air duct 307 for recycling and carbonization. The flue gas outlet of the bag filter 4 is connected to the inlet of the induced draft fan 5, which discharges the low-CO2 flue gas.

[0070] As a preferred embodiment, the suspended carbonization bed includes a sparging pipe 301, a carbonization bed cone 302 and a carbonization bed column 303 connected in sequence from bottom to top; the sparging pipe 301 is a vertical pipe, and a guide device for evenly distributing the flue gas is provided inside the sparging pipe 301, and the guide device is a structure such as a guide plate, a grille or a guide ring.

[0071] The bag dust collector 4 is provided with a vertically placed filter bag 401 and a compressed air blowing device for regularly cleaning the powder cake on the surface of the filter bag. The flue gas passes through the filter bag 401, causing the fine powder to form a powder cake on the surface of the filter bag 401. The CO2 in the flue gas continues to carbonize with the material during the process of passing through the powder cake, and the compressed air is blown regularly to clean the powder cake.

[0072] The method for preparing high-activity SCM materials from low-carbon raw materials comprises the following steps:

[0073] S1. Raw material batching and clinker burning

[0074] Siliceous raw materials, calcareous raw materials, gypsum, and mineralizers are ground into raw materials in a certain proportion, wherein the SiO2 content in the siliceous raw materials is ≥50%, the CaO content in the calcareous raw materials is ≥35%, the gypsum is one of desulfurized gypsum, phosphogypsum, and natural gypsum, and the mineralizer is one of fluorite, calcium fluoride, borax, and boric acid, or a combination of any two thereof.

[0075] The raw meal is then preheated and decomposed in a preheater 101 and a calciner 102 at the kiln's rear end before being fed into a rotary kiln 103 for calcination at a temperature of 1100-1300°C for 30-60 minutes. The calcined clinker is granular and cooled in a grate cooler 104 to produce low-carbon cement clinker. The mineral composition of low-carbon cement clinker includes α′-C2S, C4A3$, C5S2$, CS, and β-C2S. The combined content of α′-C2S and β-C2S accounts for over 40% of the total mass of the low-carbon cement clinker, the combined content of C4A3$ and C5S2$ accounts for over 20%, and CS accounts for over 20% of the total mass. The remainder is a glassy phase.

[0076] S2. Clinker grinding

[0077] Low-carbon cement clinker particles K are transported to clinker grinding system 2. Simultaneously, flue gas from the kiln preheating and precalcining system is directed to clinker grinding system 2. The flue gas Q4 entering the clinker grinding system contains 25% to 35% CO₂. After grinding, low-carbon cement clinker powder M1 is produced. The average particle size of this low-carbon cement clinker powder is less than 80 μm, with particles ranging from 5 to 80 μm accounting for over 90%. During the grinding process, some of the low-carbon cement clinker reacts with the CO₂ in the flue gas from the kiln preheating and precalcining system, reducing the CO₂ concentration in the flue gas.

[0078] S3. Carbonization to prepare highly active SCM materials

[0079] Suspension carbonization:

[0080] The clean flue gas after the preheating and pre-decomposition system at the kiln tail and the dust removal is introduced into the flue gas inlet of the air duct. The temperature of the clean flue gas Q1 entering the air duct is 100-150℃ and the CO2 concentration is 25%-35%. At the same time, the low-carbon cement clinker powder M1 with a temperature of ≤60℃ and an average particle size of less than 80μm is dispersed and fed into the air duct 307 through the spreading device. Under the action of the air flow drag, the material is suspended in the clean flue gas. The clean flue gas carries the low-carbon cement clinker powder M1 upward and is sprayed into the suspended carbonization bed through the spraying pipe 301. The suspended carbonization bed The pressure is 0 to -3000Pa, and the average wind speed in the cross section of the suspended carbonization bed is 3 to 10m / s. At the same time, water or an aqueous solution of a carbonization aid is sprayed into the suspended carbonization bed in the form of droplets through a spray gun 306, so that the water vapor in the flue gas reaches a critical saturation state (relative humidity ≥ 90%). Since the surface temperature of the material is lower than the dew point temperature of the water vapor, the water vapor condenses on the surface of the material to form a liquid film. The liquid film provides a transmission medium in the gas-solid carbonization reaction. The CO2 in the flue gas dissolves in the liquid film to react with the material to form a carbonization reaction, thereby accelerating the carbonization process.

[0081] In the carbonization aid aqueous solution, the carbonization aid is one or a combination of any two of lignin sulfonates, polycyclic aromatic salts, water-soluble resin sulfonates, and alcohol-ammonia organic compounds.

[0082] Coarse powder circulation and finished product collection:

[0083] The flue gas leaving the suspended carbonization bed carries the material and enters the bag dust collector 4 under the suction of the induced draft fan 5. After the material is collected, part of the material is returned to the air duct 307 of the low-pressure suspended carbonization bed system 3 as the circulating material M3 leaving the bag dust collector for circulating carbonization, and part of the material is led to the high-activity SCM material finished product as the first-stage finished product M2. The flue gas discharged from the bag dust collector 4 is low-CO2 flue gas Q2.

[0084] Example 2

[0085] See also Figure 3 and Figure 4 An embodiment of the present invention provides a system for preparing high-activity SCM materials from low-carbon raw materials, including a cement burning system 1, a clinker grinding system 2, a low-pressure suspended carbonization bed system 3, a secondary temperature-controlled mixing chamber 6, a powder selection and separation device 7, a bag dust collector 4 and an induced draft fan 5.

[0086] The structures of the cement burning system 1, the clinker grinding system 2, and the low-pressure suspended carbonization bed system 3 are the same as those of Example 1. Unlike Example 1, an ultrasonic generator 304 is further provided at the carbonization bed cone 302, and the ultrasonic generator 304 is located below the inlet of the spray gun 306.

[0087] The secondary temperature-controlled mixing chamber 6 is located between the suspended carbonization bed and the powder selection and separation device 7. The secondary temperature-controlled mixing chamber 6 is used to increase the temperature of the flue gas leaving the suspended carbonization bed and reduce the humidity of the flue gas. The secondary temperature-controlled mixing chamber 6 has an inlet 1, an inlet 2, and an outlet. The top outlet of the suspended carbonization bed is connected to the inlet 1 of the secondary temperature-controlled mixing chamber 6. The flue gas outlet of the kiln tail preheating and pre-decomposition system is connected to the inlet 2 of the secondary temperature-controlled mixing chamber 6 through a dust collector 107. The outlet of the secondary temperature-controlled mixing chamber 6 is connected to the flue gas inlet of the powder selection and separation device 7. A temperature measuring device 601 is provided on the outlet pipe of the secondary temperature-controlled mixing chamber 6. The temperature measuring device 601 is a thermocouple.

[0088] The powder selection and separation device 7 is a powder selector or cyclone used to separate coarse powder from fine powder in the material. A lock valve 701 and a feed valve 702 are sequentially provided on the material outlet pipe at the bottom of the powder selection and separation device 7. The feed valve 702 connects the material inlet of the air duct 307 and the finished product of the high-activity SCM material, respectively, so that the coarse powder exiting the powder selection and separation device 7 can enter the suspended carbonization bed and the finished product of the high-activity SCM material, respectively. The top flue gas outlet of the powder selection and separation device 7 is connected to the flue gas inlet of the bag filter 4. The bag filter 4 is equipped with a vertically positioned filter bag 401 and a compressed air purge device for regularly cleaning the powder cake on the surface of the filter bag 401. The material outlet of the bag filter 4 is connected to the finished product of the high-activity SCM material, and the flue gas outlet of the bag filter 4 is connected to the inlet of the induced draft fan 5.

[0089] The method for preparing high-activity SCM materials from low-carbon raw materials comprises the following steps:

[0090] S1. Raw material batching and clinker burning

[0091] Siliceous raw materials, calcareous raw materials, gypsum, and mineralizers are ground into raw materials in a certain proportion, wherein the SiO2 content in the siliceous raw materials is ≥50%, the CaO content in the calcareous raw materials is ≥35%, the gypsum is one of desulfurized gypsum, phosphogypsum, and natural gypsum, and the mineralizer is one of fluorite, calcium fluoride, borax, and boric acid, or a combination of any two thereof.

[0092] The raw meal is then preheated and decomposed in a preheater 101 and a calciner 102 at the kiln's rear end before being fed into a rotary kiln 103 for calcination at a temperature of 1100-1300°C for 30-60 minutes. The calcined clinker is granular and cooled in a grate cooler 104 to produce low-carbon cement clinker. The mineral composition of low-carbon cement clinker includes α′-C2S, C4A3$, C5S2$, CS, and β-C2S. The combined content of α′-C2S and β-C2S accounts for over 40% of the total mass of the low-carbon cement clinker, the combined content of C4A3$ and C5S2$ accounts for over 20%, and CS accounts for over 20% of the total mass. The remainder is a glassy phase.

[0093] S2. Clinker grinding

[0094] Low-carbon cement clinker particles K are transported to clinker grinding system 2. Simultaneously, flue gas from the kiln preheating and precalcining system is directed to clinker grinding system 2. The flue gas Q4 entering the clinker grinding system contains 25% to 35% CO₂. After grinding, low-carbon cement clinker powder M1 is produced. The average particle size of this low-carbon cement clinker powder is less than 200 μm, with particles ranging from 5 to 200 μm accounting for over 90%. During the grinding process, some of the low-carbon cement clinker reacts with the CO₂ in the flue gas from the kiln preheating and precalcining system, reducing the CO₂ concentration in the flue gas.

[0095] S3. Carbonization to prepare highly active SCM materials

[0096] Suspension carbonization:

[0097] The clean flue gas after the preheating and pre-decomposition system at the kiln tail and the dust removal is introduced into the flue gas inlet of the air duct 307. The temperature of the clean flue gas Q1 entering the air duct is 100-150°C and the CO2 concentration is 25%-35%. At the same time, the low-carbon cement clinker powder M1 with a temperature of ≤60°C and an average particle size of less than 200μm is dispersed and fed into the air duct 307 through the spreading device. Under the action of the air flow drag, the material is suspended in the flue gas, and the clean flue gas carries the material upward and is sprayed into the suspended carbonization bed through the spraying pipe 301. The pressure in the suspended carbonization bed is The pressure is 0 to -3000 Pa, and the average wind speed in the cross section of the suspended carbonization bed is 3 to 10 m / s. At the same time, water or an aqueous solution of a carbonization aid is sprayed into the suspended carbonization bed in the form of droplets through a spray gun 306, so that the water vapor in the flue gas reaches a critical saturation state (relative humidity ≥ 90%). Since the surface temperature of the material is lower than the dew point temperature of the water vapor, the water vapor condenses on the surface of the material to form a liquid film. The liquid film provides a transmission medium in the gas-solid carbonization reaction. The CO2 in the flue gas dissolves in the liquid film to react with the material to form a carbonization reaction, thereby accelerating the carbonization reaction.

[0098] During the suspension carbonization process, ultrasonic vibration is added to the bottom of the suspension carbonization bed. High-frequency ultrasound can accelerate the disturbance of the material and flue gas flow at the bottom of the suspension carbonization bed, speed up the reaction, reduce particle agglomeration, promote the formation of a liquid film on the material surface, and fully cover the particle surface.

[0099] In the carbonization aid aqueous solution, the carbonization aid is one or a combination of any two of lignin sulfonates, polycyclic aromatic salts, water-soluble resin sulfonates, and alcohol-ammonia organic compounds.

[0100] Coarse powder circulation:

[0101] The water vapor in the flue gas leaving the suspended carbonization bed is close to the critical saturation state (relative humidity ≥ 90%). In order to avoid condensation in the subsequent powder selection and separation device 7 and the bag dust collector 4, a secondary temperature-controlled mixing chamber 6 is set before the powder selection and separation device 7. A part of the clean flue gas leaving the kiln tail preheating and predecomposition system and after dust removal is introduced into the secondary temperature-controlled mixing chamber 6 to increase the temperature of the flue gas leaving the suspended carbonization bed and reduce the humidity of the flue gas.

[0102] Flue gas exiting the suspended carbonization bed, at a temperature of 70-90°C, carries the material and first enters the secondary temperature-controlled mixing chamber 6, where it mixes with the clean flue gas (Q3) entering the secondary temperature-controlled mixing chamber after dust removal and preheating and precalcination from the kiln tail. The flue gas temperature exiting the secondary temperature-controlled mixing chamber 6 is controlled at ≥90°C before entering the powder selection and separation device 7. Coarse powder in the material is collected and discharged from the bottom of the powder selection and separation device 7, while fine powder is discharged from the top of the device along with the flue gas. The coarse powder exiting the powder selection and separation device 7 is divided into two paths by a distributor valve 702. One portion, as the circulating material M4 exiting the powder selection and separation device, is transported back through the material pipe to the air duct 307 before entering the suspended carbonization bed for recirculation and carbonization. The other portion, as the second-stage finished product M5, is directed to the high-activity SCM material production area. The opening of the distributor valve 702 controls the circulation rate of the coarse powder in the suspended carbonization bed to prevent fully carbonized coarse powder from circulating endlessly in the suspended carbonization bed, which could cause excessive circulation load and lead to bed pressure.

[0103] Finished product collection:

[0104] The flue gas and fine powder discharged from the top of the powder selection and separation device 7 enter the bag dust collector 4 under the suction of the induced draft fan 5. The flue gas passes through the filter bag 401 with a filtration wind speed of 0.5-1.5 m / min, so that the fine powder forms a powder cake on the surface of the filter bag. The CO2 in the flue gas continues to carbonize with the material during the process of passing through the powder cake, and the compressed air is blown regularly to clean the powder cake. The powder collected from the bag dust collector is used as the first-level finished product M2, and the first-level finished product M2 and the second-level finished product M5 are used as the combined finished product M6 to be led to the high-activity SCM material finished product. The flue gas discharged from the bag dust collector is low-CO2 flue gas Q2.

[0105] The following is a detailed description of the process of preparing high-activity SCM materials from low-carbon raw materials:

[0106] Siliceous raw materials, calcareous raw materials, gypsum and mineralizers are ground into raw materials in a certain proportion, wherein the SiO2 content in the siliceous raw materials is ≥50%, the CaO content in the calcareous raw materials is ≥35%, the gypsum is phosphogypsum, and the mineralizers are fluorite and boron.

[0107] The raw meal passes through the preheater 101 and the decomposition furnace 102 at the kiln tail and is then sent to the rotary kiln 103 for calcination at a temperature of 1100-1300°C for 30-60 minutes. The calcined clinker is in granular form and is sent to the grate cooler 104 for cooling to obtain low-carbon cement clinker. The mineral composition of the low-carbon cement clinker includes: α′-C2S, C4A3$, C5S2$, CS, and β-C2S, of which the sum of the contents of α′-C2S and β-C2S accounts for 45% of the total mass of the low-carbon cement clinker, the sum of the contents of C4A3$ and C5S2$ accounts for 25% of the total mass of the low-carbon cement clinker, the content of CS accounts for 23% of the total mass of the low-carbon cement clinker, and the rest is a glass phase.

[0108] The flue gas at the kiln end of a cement firing system comes from two sources: one is fuel combustion, which is fed into the rotary kiln and precalciner, where the fuel and air combust to produce flue gas; the other is CO₂ produced by the decomposition of raw meal, where calcium carbonate in the raw meal decomposes to produce CO₂ in the precalciner. The CO₂ from raw meal decomposition mixes with the flue gas from fuel combustion to form the kiln end flue gas, which is then exhausted from the preheater 101 by the draft of high-temperature fan 106. The kiln end flue gas contains 25% to 35% CO₂. The kiln end flue gas from high-temperature fan 106 is then dedusted in dust collector 107 and then enters the suspended carbonization bed and secondary temperature-controlled mixing chamber 6 as clean flue gas, with a temperature of 100-150°C and a CO₂ concentration of 25% to 35%.

[0109] Low-carbon cement clinker particles K are transported to clinker grinding system 2. Kiln exhaust gas Q4, which contains 25% to 35% CO₂, is then directed back to clinker grinding system 2. After grinding, low-carbon cement clinker powder M1 is produced, with an average particle size of less than 200 μm and a particle size distribution of 5 to 200 μm accounting for over 90%. During the grinding process, some of the low-carbon cement clinker reacts with the CO₂ in the flue gas to carbonize, reducing the CO₂ concentration.

[0110] The pressure within the suspended carbonization bed is 0 to -3000 Pa. Clean flue gas Q1 from the air inlet pipe passes sequentially through the air duct 307 and the spray pipe 301 at the bottom of the suspended carbonization bed before being sprayed upward into the suspended carbonization bed layer. The average wind speed within the suspended carbonization bed cross section is 3 to 10 m / s. The spray pipe 301 is a vertical pipe with an internal guide plate to promote uniform distribution of the flue gas. At the carbonization bed cone 302, water or a carbonization aid aqueous solution from the water spray system 305 is sprayed into the suspended carbonization bed in the form of droplets via a spray gun 306. The amount of aqueous solution sprayed is adjusted to keep the water vapor content in the flue gas close to the critical saturation concentration.

[0111] The ultrasonic generator 304 at the bottom of the suspended carbonization bed is turned on. Room-temperature low-carbon cement clinker powder M1 (≤60°C) is dispersedly fed into the air duct 307 through the spreading device and sprayed into the suspended carbonization bed driven by the clean flue gas. Under the action of the airflow drag, the material is suspended in the flue gas. Since the surface temperature of the material is lower than the water vapor dew point, water vapor condenses on the surface of the material particles A to form a liquid film B. The liquid film provides a transmission medium in the gas-solid carbonization reaction. The CO2 in the flue gas C dissolves in the liquid film to react with the material to form a carbonization reaction, thereby accelerating the carbonization reaction.

[0112] The main carbonization reactions are as follows:

[0113]

[0114] In order to improve the activity, the carbonization degree is appropriate, and the carbonization rate of low-carbon cement clinker powder is 10% to 20%.

[0115] Flue gas exiting the suspended carbonization bed, with a temperature of 70-90°C, carries the material into the secondary temperature-controlled mixing chamber 6 and mixes with the clean flue gas Q2 entering the secondary temperature-controlled mixing chamber, maintaining the flue gas temperature at ≥90°C. The water vapor in the flue gas exiting the suspended carbonization bed approaches critical saturation (relative humidity ≥90%). To prevent condensation in the subsequent powder selection and separation device 7 and bag filter 4, a secondary temperature-controlled mixing chamber 6 is provided before the powder selection and separation device 7. A portion of the clean flue gas is introduced into the secondary temperature-controlled mixing chamber 6, raising the flue gas temperature and reducing its humidity.

[0116] The flue gas exiting the secondary temperature-controlled mixing chamber 6 carries the material into the powder selection and separation device 7. The coarse powder in the material is collected and discharged from the bottom of the powder selection and separation device 7. The coarse powder exiting the powder selection and separation device 7 is divided into two paths by the distribution valve 702. One part is transported back to the air duct through the material pipe and then enters the suspended carbonization bed for circulating carbonization. The other part is divided and directed to the high-activity SCM material finished product. The opening of the distribution valve controls the circulation rate of the coarse powder in the suspended carbonization bed to prevent the fully carbonized coarse powder from circulating in the suspended carbonization bed indefinitely, which would cause excessive circulation load and lead to suspended carbonization bed pressure. Fine powder is discharged from the air duct at the top of the powder selection and separation device along with the flue gas.

[0117] The flue gas and fine powder discharged from the top of the powder selection and separation device 7 enter the bag dust collector 4 under the suction of the induced draft fan 5. A vertically placed filter bag 401 is set inside the bag dust collector 4. The flue gas passes through the filter bag with a filtration wind speed of 0.5-1.5m / min, so that the fine powder forms a powder cake on the surface of the filter bag. The CO2 in the flue gas continues to carbonize with the material during the process of passing through the powder cake. The compressed air is blown regularly to clean the powder cake regularly. The powder collected from the bag dust collector is the highly active SCM material after carbonization. The flue gas discharged from the bag dust collector is low-CO2 flue gas Q3.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for preparing high-activity SCM materials from low-carbon raw materials, characterized by: Including cement burning system, clinker grinding system, low-pressure suspended carbonization bed system, bag dust collector and induced draft fan; The cement burning system includes a kiln tail preheating and precalcining system, a rotary kiln, and a grate cooler connected in sequence; the material outlet of the grate cooler is connected to the material inlet of the clinker grinding system, the kiln tail flue gas outlet of the kiln tail preheating and precalcining system is connected to the flue gas inlet of the clinker grinding system, and the powdered material outlet of the clinker grinding system is connected to the material inlet of the low-pressure suspended carbonization bed system; The low-pressure suspended carbonization bed system includes an air duct, a suspended carbonization bed and a water spray system. The air duct is located below the suspended carbonization bed, and the bottom of the air duct is a flue gas inlet. The kiln tail flue gas outlet of the kiln tail preheating and predecomposition system is connected to the flue gas inlet of the air duct through a dust collector. The material inlet of the low-pressure suspended carbonization bed system is arranged in the air duct or the suspended carbonization bed, so that the powdered material moves upward under the drive of the flue gas. The top of the air duct is connected to the bottom of the suspended carbonization bed, and a spray pipe is provided at the connection part, so that the clean flue gas after the dust removal from the kiln tail preheating and predecomposition system is sprayed upward into the suspended carbonization bed; a plurality of spray guns are provided at the lower part of the suspended carbonization bed and are located above the spray pipe. The outlet of the water spray system is connected to the spray gun inlet, so that the aqueous solution is sprayed into the suspended carbonization bed in the form of droplets. The water vapor in the flue gas in the suspended carbonization bed forms a critical saturation state of water vapor-water droplets, and a liquid film is formed on the surface of the material; The outlet of the suspended carbonization bed is connected to the flue gas inlet of the bag dust collector; the material outlet of the bag dust collector is connected to the high-activity SCM material finished product, or is respectively connected to the high-activity SCM material finished product and the material inlet of the low-pressure suspended carbonization bed system, and the flue gas outlet of the bag dust collector is connected to the induced draft fan inlet.

2. The system for preparing high-activity SCM materials from low-carbon raw materials according to claim 1, characterized in that: The suspended carbonization bed includes a spray pipe, a carbonization bed cone and a carbonization bed column connected in sequence from bottom to top; the spray pipe is a vertical pipe, and a guide device for evenly distributing the flue gas is provided inside the spray pipe.

3. The system for preparing high-activity SCM materials from low-carbon raw materials according to claim 2, characterized in that: An ultrasonic generator is provided at the vertebral body of the carbonization bed.

4. The system for preparing high-activity SCM materials from low-carbon raw materials according to claim 1, characterized in that: A secondary temperature-controlled mixing chamber is provided between the suspended carbonization bed and the bag dust collector, and the secondary temperature-controlled mixing chamber is used to increase the temperature of the flue gas exiting the suspended carbonization bed and reduce the humidity of the flue gas; the secondary temperature-controlled mixing chamber has an inlet one, an inlet two and an outlet, the top outlet of the suspended carbonization bed is connected to the inlet one of the secondary temperature-controlled mixing chamber, the kiln tail flue gas outlet of the kiln tail preheating and predecomposition system is connected to the inlet two of the secondary temperature-controlled mixing chamber through the dust collector, and the outlet of the secondary temperature-controlled mixing chamber is connected to the flue gas inlet of the bag dust collector.

5. The system for preparing high-activity SCM materials from low-carbon raw materials according to claim 4, characterized in that: A temperature measuring device is provided on the outlet pipe of the secondary temperature-controlled mixing chamber.

6. The system for preparing high-activity SCM materials from low-carbon raw materials according to claim 4, characterized in that: A powder selection and separation device is arranged between the secondary temperature-controlled mixing chamber and the bag dust collector. The outlet of the secondary temperature-controlled mixing chamber is connected to the flue gas inlet of the powder selection and separation device. The bottom material outlet of the powder selection and separation device is connected to the material inlet of the low-pressure suspended carbonization bed system. The top flue gas outlet of the powder selection and separation device is connected to the flue gas inlet of the bag dust collector.

7. The system for preparing high-activity SCM materials from low-carbon raw materials according to claim 6, characterized in that: The powder selection and separation device is a powder selector or a cyclone, which is used to separate coarse powder and fine powder in the material.

8. The system for preparing high-activity SCM materials from low-carbon raw materials according to claim 6, characterized in that: An air lock valve and a material distribution valve are sequentially arranged on the material pipe at the bottom material outlet of the powder selection and separation device. The bottom material outlet of the powder selection and separation device is also connected to the high-activity SCM material finished product through the material distribution valve, so that the coarse powder leaving the powder selection and separation device can enter the suspended carbonization bed and the high-activity SCM material finished product respectively.

9. The system for preparing high-activity SCM materials from low-carbon raw materials according to claim 1, characterized in that: The bag dust collector is provided with a vertically placed filter bag, and is also provided with a compressed air blowing device for regularly cleaning powder cakes on the surface of the filter bag.

10. A method for preparing a high-activity SCM material from a low-carbon raw material using the system according to any one of claims 1 to 9, comprising the following steps: S1. Raw material batching and clinker burning The siliceous raw materials, calcium raw materials, gypsum and mineralizers are ground into raw materials in a certain proportion. The raw materials are then preheated and decomposed in the preheating and pre-decomposition system at the kiln tail and then sent to the rotary kiln for calcination at a temperature of 1100-1300°C. The calcined clinker is sent to a grate cooler for cooling to obtain low-carbon cement clinker. S2. Clinker grinding The low-carbon cement clinker particles are transported to the clinker grinding system, and the flue gas from the kiln preheating and pre-decomposition system is introduced into the clinker grinding system. The flue gas from the kiln preheating and pre-decomposition system contains 25% to 35% CO2, which is ground into low-carbon cement clinker powder. The average particle size of the low-carbon cement clinker powder is less than 200 μm. S3. Carbonization to prepare highly active SCM materials Suspension carbonization: The clean flue gas after the preheating and pre-decomposition system at the kiln tail and the dust removal is introduced into the flue gas inlet of the air duct. The clean flue gas after the preheating and pre-decomposition system at the kiln tail and the dust removal has a temperature of 100-150°C and a CO2 concentration of 25%-35%. The clean flue gas moves upward and is sprayed into the suspended carbonization bed through the spray pipe. At the same time, low-carbon cement clinker powder with a temperature of ≤60°C and an average particle size of less than 200μm is dispersed and fed into the air duct or the suspended carbonization bed, so that the material is suspended in the clean flue gas under the action of air flow drag. The pressure in the suspended carbonization bed is 0-3000Pa, and the average wind speed in the cross section of the suspended carbonization bed is 3-10m / s. At the same time, water or a carbonization aid aqueous solution is sprayed into the suspended carbonization bed in the form of droplets through a spray gun, so that the water vapor in the flue gas reaches a critical saturation state. The water vapor forms a liquid film on the surface of the material, and the CO2 in the flue gas dissolves in the liquid film to react with the material to form a carbonization reaction. Coarse powder circulation and finished product collection: The flue gas from the suspended carbonization bed carries the material and enters the bag dust collector under the draft of the induced draft fan. After the material is collected, part of it returns to the low-pressure suspended carbonization bed system for circulating carbonization, and part of it is led to the high-activity SCM material finished product; or, all of it is led to the high-activity SCM material finished product.

11. The method for preparing high-activity SCM materials from low-carbon raw materials according to claim 10, characterized in that: The SiO2 content in the siliceous raw material is ≥50%, the CaO content in the calcareous raw material is ≥35%, the gypsum is one of desulfurized gypsum, phosphogypsum, and natural gypsum, and the mineralizer is one of fluorite, calcium fluoride, borax, and boric acid, or a combination of any two of them.

12. The method for preparing high-activity SCM materials from low-carbon raw materials according to claim 10, characterized in that: The mineral composition of the low-carbon cement clinker includes: α′-C2S, C4A3$, C5S2$, CS, and β-C2S, wherein the sum of the contents of α′-C2S and β-C2S accounts for more than 40% of the total mass of the low-carbon cement clinker, the sum of the contents of C4A3$ and C5S2$ accounts for more than 20% of the total mass of the low-carbon cement clinker, the content of CS accounts for more than 20% of the total mass of the low-carbon cement clinker, and the rest is a glass phase.

13. The method for preparing high-activity SCM materials from low-carbon raw materials according to claim 10, characterized in that: During the suspension carbonization process, ultrasonic vibration is added to the bottom of the suspension carbonization bed.

14. The method for preparing high-activity SCM materials from low-carbon raw materials according to claim 10, characterized in that: In the carbonization aid aqueous solution, the carbonization aid is one or a combination of any two of lignin sulfonates, polycyclic aromatic salts, water-soluble resin sulfonates, and alcohol-ammonia organic compounds.

15. The method for preparing high-activity SCM materials from low-carbon raw materials according to claim 10, characterized in that: The flue gas carrying materials from the suspended carbonization bed first enters the secondary temperature-controlled mixing chamber and mixes with part of the clean flue gas from the kiln tail preheating and pre-decomposition system and dust removal, and then enters the bag dust collector; the flue gas temperature from the secondary temperature-controlled mixing chamber is controlled at ≥90℃.

16. The method for preparing high-activity SCM materials from low-carbon raw materials according to claim 15, characterized in that: The flue gas from the secondary temperature-controlled mixing chamber carries the material into the powder selection and separation device first. The coarse powder in the material is collected and discharged from the bottom of the powder selection and separation device. Part of it returns to the low-pressure suspended carbonization bed system for circulating carbonization, and part is led to the high-activity SCM material finished product. The fine powder is discharged from the top of the powder selection and separation device with the flue gas and enters the bag dust collector. The flue gas passes through the filter bag with a filtration wind speed of 0.5-1.5m / min, so that the fine powder forms a powder cake on the surface of the filter bag. The CO2 in the flue gas continues to carbonize with the material during the process of passing through the powder cake, and the compressed air is blown regularly to clean the powder cake. The powder collected from the bag dust collector is carbonized micropowder material, which is led to the high-activity SCM material finished product.

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