Method for preparing low-carbon cement by using inactivated limestone-based calcium-based CO2 adsorbent

Abstract

The invention belongs to the technical field of building material preparation, and discloses a method for preparing low-carbon cement by using an inactivated limestone-based calcium-based CO2 adsorbent, the inactivated limestone-based adsorbent is used as a calcareous raw material and is mixed with other components to prepare a cement raw material, and the cement raw material comprises the following components: 62-67% of CaO, 20-24% of SiO2, 4-7% of Al2O3, 2-5% of Fe2O3, less than or equal to 5% of MgO and less than or equal to 1.5% of free calcium oxide. And then calcining the raw material into cement clinker, and mixing the cement clinker with the traditional cement clinker to finally prepare the low-carbon cement. According to the invention, a unique process of firstly preparing the inactivated adsorbent into the clinker and then mixing is adopted, so that the content of free calcium oxide in the finished cement product is effectively controlled, and double carbon reduction benefits are realized: the use amount of a traditional limestone raw material is directly reduced, and the inactivated adsorbent is used as a negative carbon material for resource utilization, so that the cost is reduced. The total carbon emission of the whole life cycle of the cement is obviously reduced.

Description

Technical Field

[0001] This invention belongs to the technical field of building material preparation, and more specifically, relates to a method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent. Background Technology

[0003] To achieve carbon emission reduction, the cement industry has taken some measures. Regarding raw materials for cement production, some have proposed alternative raw material solutions, and initial results have been achieved. Specifically, this involves using solid waste such as fly ash, slag, and carbide slag to replace traditional limestone and clayey raw materials, achieving raw material recycling. This solution has also played a role in conserving natural resources and reducing CO2 emissions. However, solid waste comes from a wide range of sources, and the chemical composition of solid waste from different manufacturers and their products varies, making the content of effective components that solid waste can provide as cement raw materials unstable, affecting the continuity and stability of cement production. Even using a point-to-point model between cement plants and specific factories, the generation of solid waste is not a one-day process, making large-scale cement production difficult.

[0004] Meanwhile, calcium recycling technology, as an advanced carbon capture, utilization, and storage (CCUS) technology, utilizes calcium-based adsorbents to adsorb carbon dioxide and regenerates it under high-temperature conditions, enabling the recycling of carbon dioxide and providing a new approach to carbon emission reduction in the cement industry. Calcium-based adsorbents prepared from limestone, with their high CO2 adsorption capacity and relatively abundant resource background, have become the core material in calcium recycling technology. However, in practical applications, the deactivation of calcium-based adsorbents has always been a pressing technical challenge. It is worth noting that after deactivation, the main component of calcium-based adsorbents remains calcium carbonate, essentially the same as limestone, the main raw material used in cement production. Therefore, even after losing its adsorption function, the deactivated limestone-based calcium adsorbent's chemical composition and structure remain compatible with the raw material system for cement production. Based on this characteristic, using deactivated limestone-based calcium adsorbents to replace part of the cement raw materials in cement production can not only achieve the preparation of low-carbon cement but also effectively dispose of the deactivated adsorbent, resulting in significant environmental and economic benefits.

[0005] Although this technological approach has significant potential for carbon reduction, current research is still in its early stages, lacking clear technical approaches and pathways. Therefore, exploring the application of deactivated limestone-based calcium adsorbents in cement production, particularly their impact on cement performance and production processes, is a pressing scientific issue. Further research into alternative methods and processes for deactivated limestone-based calcium adsorbents in cement could provide new technological pathways for the low-carbon development of the cement industry and promote its sustainable development.

[0006] Therefore, in order to address the above problems, it is urgent to design a process and method for preparing low-carbon cement clinker using deactivated limestone-based CO2 adsorbents, in order to realize the treatment of large quantities of deactivated calcium-based adsorbents, and at the same time meet the carbon emission reduction needs of industries such as cement manufacturing, concrete production, and building materials manufacturing. Summary of the Invention

[0007] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a method for preparing low-carbon cement using deactivated limestone-based calcium-based CO2 adsorbents. The aim is to maximize the utilization of cement-like components contained in the deactivated limestone-based adsorbents while controlling the free calcium oxide content in the cement. This solves the technical problems of effective disposal and resource utilization of deactivated limestone-based calcium-based adsorbents, as well as precise control of the free calcium oxide content in the finished cement.

[0008] To achieve the above objectives, according to one aspect of the present invention, a method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent is provided, comprising the following steps: S1: Preparation of raw materials using deactivated limestone-based calcium-based adsorbents; S11: The limestone raw materials in cement raw materials were prepared using different deactivated calcium-based adsorbents, wherein the mass fractions of each component were: CaO 62-67%, SiO2 20-24%, Al2O3 4-7%, Fe2O3 2-5%, MgO ≤5%, and free calcium oxide ≤1.5%; S12: Grind the raw material obtained in S11, and then store the ground raw material in a raw material homogenization bin for further homogenization of components. The raw material homogenization bin is set as a continuous homogenization bin or an intermittent homogenization bin.

[0009] S2: The raw material prepared in S1 is preheated and decomposed, then calcined into clinker, cooled and sieved to obtain clinker made from deactivated limestone-based calcium adsorbent. S21: The raw materials are preheated and decomposed. The raw materials enter a five-stage cyclone preheater, where they undergo countercurrent heat exchange using the high-temperature flue gas from the rotary kiln outlet to achieve preheating and partial decomposition. The preheated raw materials then enter the decomposition furnace and are mixed with the injected fuel for combustion. The calcium carbonate decomposition (CaCO3→CaO+CO2↑) is completed at 850-950℃, with a decomposition rate ≥90%. S22: The raw meal decomposed from S21 is calcined into clinker: The decomposed raw meal enters the rotary kiln and moves forward with the kiln body as it rotates, passing through the transition zone, the firing zone and the cooling zone in sequence. S23: Cooling the clinker fired in S22: The high-temperature clinker enters the grate cooler, and cold air is blown in from below the grate to exchange heat with the clinker in a countercurrent manner, reducing the clinker temperature from above 1000℃ to below ambient temperature +65℃. S24: Screen the clinker cooled in S23 to remove large pieces of clinker ≥25mm, return it to the crusher for further crushing, and then send it to the clinker silo for storage. S3: Preparation of low-carbon cement using deactivated limestone-based calcium-based CO2 adsorbent; S31: Clinker made with S2 deactivated limestone-based calcium adsorbent is mixed with clinker made from original cement in a certain proportion, wherein the proportion of deactivated limestone-based calcium adsorbent is 0-15%; the clinker made from original cement comprises 50-70% tricalcium silicate, 15-30% dicalcium silicate, 5-10% tricalcium aluminate, and 5-15% tetracalcium aluminoferrite. S32: The mixed clinker obtained in S31 is batched with gypsum and admixtures. The batching ratio is determined according to the type of cement. The batching is precisely controlled by quantitative feeding equipment in the clinker silo, admixture silo, and gypsum silo, with an error of ≤±1%, to ensure the stability of cement composition. S33: The mixed ingredients obtained in S32 are ground. The process includes pretreatment, ball mill grinding, powder classification, and finally low-carbon cement is prepared.

[0010] Preferably, the grinding method in S12 adopts a vertical mill. The raw material falls into the center of the grinding disc through the feed port. The rotation of the grinding disc generates centrifugal force to throw the raw material to the bottom of the grinding roller. The grinding roller presses and crushes the raw material. At the same time, hot air rises from the bottom of the grinding disc to dry the moisture of the raw material and carry the fine powder into the top classifier. The hot air comes from the waste heat of the clinker cooler or the hot air furnace, and the temperature is 250-350℃.

[0011] Preferably, the steps of raw material homogenization in S12 through a continuous homogenization silo are as follows: raw materials are fed from multiple points at the top of the silo to achieve an initial uniform distribution of raw materials; the raw materials are aerated in a preset sequence through the bottom aeration device to form a dynamic "funnel flow" effect in the silo; and the raw material components are uniformly mixed with a homogenization coefficient ≥ 8.

[0012] Preferably, the temperature of the high-temperature flue gas at the rotary kiln outlet in S21 is 1000-1100℃. The raw material enters from the uppermost preheater C1 stage and passes through the C2-C5 stage preheaters in sequence with the airflow, where the temperature rises from room temperature to 800-850℃, while the flue gas temperature drops to 300-350℃.

[0013] Preferably, the temperature of the transition zone in S22 is 950-1300℃: CaO in the raw material reacts initially with SiO2, Al2O3, and Fe2O3 to generate low-melting-point minerals, and the material begins to agglomerate; the temperature of the firing zone is 1450-1550℃, which is the core reaction zone, generating the main clinker mineral C3S (2CaO•SiO2+CaO→3CaO·SiO2), and the material forms clinker particles with a particle size of 5-25mm; the temperature of the cooling zone is 1300-1000℃, and the clinker enters the cooling zone from the firing zone and is initially cooled by the cold air at the kiln tail, avoiding the direct entry of high-temperature clinker into the cooler and causing equipment damage.

[0014] Preferably, the hot air temperature after heat exchange in S23 is 300-800℃, divided into three parts: ① 600-800℃ hot air is sent to the decomposition furnace as secondary air; ② 300-400℃ hot air is sent to the preheater as tertiary air; ③ the remaining hot air is used for raw material drying or power generation, with a waste heat recovery rate ≥70%. Simultaneously, rapid cooling can prevent clinker from drying out. break down, It easily decomposes below 1250℃. At the same time, inhibit Towards Transformation Volume expansion can cause clinker to pulverize, thus ensuring clinker strength.

[0015] Preferably, when the cement type in S32 is P•I silicate cement, the batching composition is: 100% clinker and 3-5% gypsum, with no admixtures.

[0016] Preferably, when the cement type in S32 is P•O ordinary Portland cement, the batching components are: 70%-80% clinker, 3-5% gypsum, and 15-25% admixtures. The admixtures can be one or more of granulated blast furnace slag and fly ash.

[0017] Preferably, the pretreatment process in S33 is as follows: the mixed material first enters the roller press and is squeezed into a cake by the high-pressure roller, and more than 80% of the material in the cake has a particle size ≤2mm.

[0018] Preferably, the ball mill grinding process in S33 is as follows: the material cake enters the ball mill for grinding and refining; the powder classification process involves the ball mill outlet material entering a high-efficiency powder classifier to separate qualified fine powder and coarse powder, with the coarse powder returned to the roller press or ball mill for regrinding; the specific surface area of ​​the qualified fine powder... ≤ 4% residue on 80μm sieve.

[0019] In summary, compared with the prior art, the method for preparing low-carbon cement using deactivated limestone-based calcium-based CO2 adsorbent provided by the present invention has the following beneficial effects: 1. Limestone-based calcium-based adsorbents, before deactivation, can cyclically adsorb large amounts of CO2, thus acting as a carbon-negative material. This invention introduces deactivated limestone-based calcium-based CO2 adsorbents into high-carbon-emission cement, reducing the amount of raw materials required for the original cement and lowering carbon emissions. Furthermore, the blended cement can also be considered a carbon-negative material, significantly reducing cement carbon emissions. Compared to existing processes, this invention solves the problem of improperly disposing of large quantities of deactivated adsorbents, providing an effective solution for the resource utilization of deactivated calcium-based adsorbents.

[0020] 2. This invention effectively controls the free calcium oxide content in blended cement by first preparing the deactivated adsorbent into cement clinker and then blending it with traditional cement clinker. During the cement clinker calcination process, the calcium oxide in the deactivated adsorbent is appropriately converted, reducing the free calcium oxide content and avoiding the impact of excessive free calcium oxide on the cement's setting time and hardening rate, thus ensuring the cement's quality stability. If the deactivated adsorbent is directly added to cement as aggregate, its high calcium oxide content makes it difficult to effectively control the free calcium oxide, potentially leading to instability in the cement's setting time and hardening rate.

[0021] 3. No additional process steps are added during the production of cement raw materials from deactivated limestone-based calcium-based adsorbents. The entire blending and preparation process can be completed using existing cement preparation equipment, utilizing the deactivated adsorbents as resources without incurring additional production costs. This innovative process not only achieves the resource utilization of deactivated adsorbents, fully utilizing their calcium carbonate component and reducing the environmental impact of waste, but also improves production simplicity and cost-effectiveness without adding new process steps. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the process flow of a method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent according to the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0024] The embodiments of this invention are based on the determined component ratios in Table 1, with CaO, SiO2, and other substances derived from deactivated limestone-based CO2 adsorbents. The prepared cement samples were tested for cement performance according to GB175-2023. Unless otherwise specified, all operating methods are industry-standard methods.

[0025]

[0026] Example 1 Example 1 describes the preparation of low-carbon cement using a deactivated limestone-based CO2 adsorbent to replace 5% of the clinker. 781g of deactivated limestone-based CO2 adsorbent, 146g of quartz sand, 36g of alumina, 25g of iron oxide, and 12g of magnesium oxide, totaling 1000g of raw materials, were weighed.

[0027] The raw materials are mixed and poured into the vertical mill disc through the feed inlet. At the same time, a hot air furnace generates 300°C hot air that rises from the bottom of the mill disc. After grinding, the ground raw material is stored in the raw material homogenization silo for further homogenization of the components, with a homogenization coefficient of 10.

[0028] The raw meal is then fed into the top stage (C1 stage) of a five-stage cyclone preheater, and sequentially passes through C2-C5 stage preheaters as the airflow descends, raising the temperature from ambient to 820℃ while the flue gas temperature drops to 320℃. The preheated raw meal is then placed in a decomposition furnace, where it is mixed and burned with injected pulverized coal at 900℃. The decomposed raw meal is then poured into a rotary kiln, set at a 4% inclination and a rotation speed of 3 r / min, to ensure thorough firing and initial cooling with cold air from the kiln tail. The high-temperature clinker is then placed in a grate cooler, where cold air is blown in from below the grate to exchange heat with the clinker in a counter-current manner. After the clinker temperature drops to 80℃, the hot air is divided into three parts: 600-800℃ hot air is sent to the decomposition furnace as secondary air, 300-400℃ hot air is sent to the preheaters as tertiary air, and the remaining hot air is used for raw meal drying or power generation. The cooled clinker is then sieved through a 25mm sieve and stored in a clinker silo. The large pieces of clinker that are screened out are put into a crusher for further crushing and then the screening process is repeated.

[0029] Clinker made from raw cement and clinker made from deactivated limestone-based calcium adsorbent are mixed in a 95:5 ratio, with approximately 5% dihydrate gypsum added. The batching is fed through a feeder to ensure stable cement composition. The mixture is first fed into a roller press, where it is extruded into a "cake" using a high-pressure roller at 12 MPa. The cake then enters a ball mill for grinding and refining. The material exiting the ball mill is then sent to a classifier to separate the specific surface area. The qualified fine powder is 80μm, and the unqualified coarse powder is returned to the roller press for re-grinding.

[0030] The low-carbon cement powder prepared by the method described in Example 1 was tested for cement performance according to GB 175-2023. The sample had a flexural strength of 4.7 MPa and a compressive strength of 18.6 MPa at 3 days, and a flexural strength of 8.3 MPa and a compressive strength of 44.2 MPa after 28 days, with a free calcium oxide content of 0.48%, which fully complies with the relevant national standards. The relevant test data are shown in Table 2 below.

[0031]

[0032] Example 2 Example 2 describes the preparation of low-carbon cement using a deactivated limestone-based CO2 adsorbent to replace 10% of the clinker. 781g of deactivated limestone-based CO2 adsorbent, 146g of quartz sand, 36g of alumina, 25g of iron oxide, and 12g of magnesium oxide, totaling 1000g of raw materials, were weighed.

[0033] The raw materials are mixed and poured into the vertical mill disc through the feed inlet. At the same time, a hot air furnace generates 300°C hot air that rises from the bottom of the mill disc. After grinding, the ground raw material is stored in the raw material homogenization silo for further homogenization of the components, with a homogenization coefficient of 10.

[0034] The raw meal is then fed into the top stage (C1 stage) of a five-stage cyclone preheater, and sequentially passes through C2-C5 stage preheaters as the airflow descends, raising the temperature from ambient to 820℃ while the flue gas temperature drops to 320℃. The preheated raw meal is then placed in a decomposition furnace, where it is mixed and burned with injected pulverized coal at 900℃. The decomposed raw meal is then poured into a rotary kiln, set at a 4% inclination and a rotation speed of 3 r / min, to ensure thorough firing and initial cooling with cold air from the kiln tail. The high-temperature clinker is then placed in a grate cooler, where cold air is blown in from below the grate to exchange heat with the clinker in a counter-current manner. After the clinker temperature drops to 80℃, the hot air is divided into three parts: 600-800℃ hot air is sent to the decomposition furnace as secondary air, 300-400℃ hot air is sent to the preheaters as tertiary air, and the remaining hot air is used for raw meal drying or power generation. The cooled clinker is then sieved through a 25mm sieve and stored in a clinker silo. The large pieces of clinker that are screened out are put into a crusher for further crushing and then the screening process is repeated.

[0035] Clinker made from raw cement and clinker made from deactivated limestone-based calcium adsorbent are mixed in a 90:10 ratio, with approximately 5% dihydrate gypsum added. The batching is fed through a feeder to ensure stable cement composition. The mixture is first fed into a roller press, where it is compressed into a "cake" using a high-pressure roller at 12 MPa. The cake then enters a ball mill for grinding and refining. The material exiting the ball mill is then sent to a classifier to separate the specific surface area. The qualified fine powder with a particle size of 80μm was obtained, while the unqualified coarse clinker powder was returned to the roller press for re-grinding. Low-carbon cement powder with a replacement ratio of 10% was obtained.

[0036] The low-carbon cement powder prepared by the method described in Example 2 was tested for cement performance according to GB 175-2023. The sample had a flexural strength of 4.5 MPa and a compressive strength of 18.1 MPa at 3 days, and a flexural strength of 7.8 MPa and a compressive strength of 43.4 MPa after 28 days, with a free calcium oxide content of 0.44%, which fully complies with the relevant national standards. The relevant test data are shown in Table 3 below.

[0037]

[0038] Example 3 Example 3 describes the preparation of low-carbon cement using a deactivated limestone-based CO2 adsorbent to replace 15% of the clinker. 781g of deactivated limestone-based CO2 adsorbent, 146g of quartz sand, 36g of alumina, 25g of iron oxide, and 12g of magnesium oxide, totaling 1000g of raw materials, were weighed.

[0039] The raw materials are mixed and poured into the vertical mill disc through the feed inlet. At the same time, a hot air furnace generates 300°C hot air that rises from the bottom of the mill disc. After grinding, the ground raw material is stored in the raw material homogenization silo for further homogenization of the components, with a homogenization coefficient of 10.

[0040] The raw meal is then fed into the top stage (C1 stage) of a five-stage cyclone preheater, and sequentially passes through C2-C5 stage preheaters as the airflow descends, raising the temperature from ambient to 820℃ while the flue gas temperature drops to 320℃. The preheated raw meal is then placed in a decomposition furnace, where it is mixed and burned with injected pulverized coal at 900℃. The decomposed raw meal is then poured into a rotary kiln, set at a 4% inclination and a rotation speed of 3 r / min, to ensure thorough firing and initial cooling with cold air from the kiln tail. The high-temperature clinker is then placed in a grate cooler, where cold air is blown in from below the grate to exchange heat with the clinker in a counter-current manner. After the clinker temperature drops to 80℃, the hot air is divided into three parts: 600-800℃ hot air is sent to the decomposition furnace as secondary air, 300-400℃ hot air is sent to the preheaters as tertiary air, and the remaining hot air is used for raw meal drying or power generation. The cooled clinker is then sieved through a 25mm sieve and stored in a clinker silo. The large pieces of clinker that are screened out are put into a crusher for further crushing and then the screening process is repeated.

[0041] Clinker made from raw cement and clinker made from deactivated limestone-based calcium adsorbent are mixed in a ratio of 85:15, with approximately 5% dihydrate gypsum added. The batching is fed through a feeder to ensure stable cement composition. The mixture is first fed into a roller press, where it is extruded into a "cake" using a high-pressure roller at 12 MPa. The cake then enters a ball mill for grinding and refining. The material exiting the ball mill is sent to a classifier to separate the specific surface area. The qualified fine powder with a particle size of 80μm was obtained, while the unqualified coarse clinker powder was returned to the roller press for re-grinding. Low-carbon cement powder with a replacement ratio of 15% was obtained.

[0042] The low-carbon cement powder prepared by the method described in Example 3 was tested for cement performance according to GB 175-2023. The sample had a flexural strength of 4.2 MPa and a compressive strength of 17.5 MPa at 3 days, and a flexural strength of 7.6 MPa and a compressive strength of 42.9 MPa after 28 days, with a free calcium oxide content of 0.41%, which fully complies with the relevant national standards. The relevant test data are shown in Table 4 below.

[0043]

[0044] Compare with Example 1 Weigh out 1000g of raw materials, including 781g of limestone, 146g of quartz sand, 36g of alumina, 25g of iron oxide, and 12g of magnesium oxide.

[0045] The raw materials are mixed and poured into the vertical mill disc through the feed inlet. At the same time, a hot air furnace generates 300°C hot air that rises from the bottom of the mill disc. After grinding, the ground raw material is stored in the raw material homogenization silo for further homogenization of the components, with a homogenization coefficient of 10.

[0046] The raw meal is then fed into the top stage (C1 stage) of a five-stage cyclone preheater, and sequentially passes through C2-C5 stage preheaters as the airflow descends, raising the temperature from ambient to 820℃ while the flue gas temperature drops to 320℃. The preheated raw meal is then placed in a decomposition furnace, where it is mixed and burned with injected pulverized coal at 900℃. The decomposed raw meal is then poured into a rotary kiln, set at a 4% inclination and a rotation speed of 3 r / min, to ensure thorough firing and initial cooling with cold air from the kiln tail. The high-temperature clinker is then placed in a grate cooler, where cold air is blown in from below the grate to exchange heat with the clinker in a counter-current manner. After the clinker temperature drops to 80℃, the hot air is divided into three parts: 600-800℃ hot air is sent to the decomposition furnace as secondary air, 300-400℃ hot air is sent to the preheaters as tertiary air, and the remaining hot air is used for raw meal drying or power generation. The cooled clinker is then sieved through a 25mm sieve and stored in a clinker silo. The large pieces of clinker that are screened out are put into a crusher for further crushing and then the screening process is repeated.

[0047] The low-carbon cement powder prepared by the method described in Comparative Example 1 was tested for cement performance according to GB 175-2023. The sample had a flexural strength of 4.6 MPa and a compressive strength of 18.5 MPa at 3 days, and a flexural strength of 8.2 MPa and a compressive strength of 43.7 MPa after 28 days, with a free calcium oxide content of 0.67%, which fully complies with the relevant national standards. The relevant test data are shown in Table 5 below.

[0048]

[0049] Tables 2-5 above show the test results for Examples 1-3 and Control Example 1, respectively. Comparing Tables 2, 3, 4 and Table 5, it can be seen that the cement maintains good performance, including setting time, strength, and stability, at blending ratios of 5%, 10%, and 15%. Blended cement exhibits excellent performance in controlling free calcium oxide content, effectively controlling the hydration process and cracking.

[0050] This invention proposes a method for preparing low-carbon cement using deactivated limestone-based calcium-based CO2 adsorbents. The deactivated limestone-based CO2 adsorbent is used as raw material to produce clinker, which is then mixed with cement clinker. Compared to existing cement production technologies, this method significantly reduces carbon emissions from cement and solves the problem of improper disposal of large quantities of deactivated adsorbents, without incurring additional production costs. Furthermore, compared to existing clinker replacement technologies, this invention achieves controllable free calcium oxide in the produced cement, meaning that the cement setting time and hardening speed can be controlled, resulting in higher-quality low-carbon cement and providing effective support for the carbon capture needs of the cement production and building materials industries.

[0051] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent, characterized in that: Includes the following steps: S1: Preparation of raw materials using deactivated limestone-based calcium-based adsorbents; S11: The limestone raw materials in cement raw materials were prepared using different deactivated calcium-based adsorbents, wherein the mass fractions of each component were: CaO 62-67%, SiO2 20-24%, Al2O3 4-7%, Fe2O3 2-5%, MgO ≤5%, and free calcium oxide ≤1.5%; S12: Grind the raw material obtained in S11, and then store the ground raw material in a raw material homogenization bin for further homogenization of components. The raw material homogenization bin is set as a continuous homogenization bin or an intermittent homogenization bin. S2: The raw material prepared in S1 is preheated and decomposed, then calcined into clinker, cooled and sieved to obtain clinker made from deactivated limestone-based calcium adsorbent. S21: The raw materials are preheated and decomposed. The raw materials enter a five-stage cyclone preheater, where they undergo countercurrent heat exchange using the high-temperature flue gas from the rotary kiln outlet to achieve preheating and partial decomposition. The preheated raw materials then enter the decomposition furnace and are mixed with the injected fuel for combustion. The calcium carbonate is decomposed at 850-950℃, with a decomposition rate of ≥90%. S22: The raw meal decomposed from S21 is calcined into clinker: The decomposed raw meal enters the rotary kiln and moves forward with the kiln body as it rotates, passing through the transition zone, the firing zone and the cooling zone in sequence. S23: Cooling the clinker fired in S22: The high-temperature clinker enters the grate cooler, and cold air is blown in from below the grate to exchange heat with the clinker in a countercurrent manner, reducing the clinker temperature from above 1000℃ to below ambient temperature +65℃. S24: Screen the clinker cooled in S23 to remove large pieces of clinker ≥25mm, return it to the crusher for further crushing, and then send it to the clinker silo for storage. S3: Preparation of low-carbon cement using deactivated limestone-based calcium-based CO2 adsorbent; S31: Clinker made with S2 deactivated limestone-based calcium adsorbent is mixed with clinker made from original cement in a certain proportion, wherein the proportion of deactivated limestone-based calcium adsorbent is 0-15%; the clinker made from original cement comprises 50-70% tricalcium silicate, 15-30% dicalcium silicate, 5-10% tricalcium aluminate, and 5-15% tetracalcium aluminoferrite. S32: The mixed clinker obtained in S31 is batched with gypsum and admixtures. The batching ratio is determined according to the type of cement. The batching is precisely controlled by quantitative feeding equipment in the clinker silo, admixture silo, and gypsum silo. S33: The mixed ingredients obtained in S32 are ground. The process includes pretreatment, ball mill grinding, powder classification, and finally low-carbon cement is prepared.

2. The method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent as described in claim 1, characterized in that: The grinding method in S12 adopts a vertical mill. The raw material falls into the center of the grinding disc through the feed port. The rotation of the grinding disc generates centrifugal force to throw the raw material to the bottom of the grinding roller. The grinding roller presses and crushes the raw material. At the same time, hot air rises from the bottom of the grinding disc to dry the moisture of the raw material and carry the fine powder into the top classifier. The hot air comes from the waste heat of the clinker cooler or the hot air furnace, and the temperature is 250-350℃.

3. The method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent as described in claim 1, characterized in that: The steps for raw material homogenization in S12 using a continuous homogenization silo are as follows: raw materials are fed from multiple points at the top of the silo to achieve an initial uniform distribution; the raw materials are aerated in a preset sequence through a bottom aeration device to create a dynamic "funnel flow" effect; and the raw material components are uniformly mixed with a homogenization coefficient ≥ 8.

4. The method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent as described in claim 1, characterized in that: The temperature of the high-temperature flue gas at the rotary kiln outlet described in S21 is 1000-1100℃. The raw material enters from the top-level preheater C1 and flows downward through the C2-C5 preheaters in sequence, where the temperature rises from room temperature to 800-850℃, while the flue gas temperature drops to 300-350℃.

5. A method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent as described in claim 1, characterized in that: The temperature of the transition zone in S22 is 950-1300℃: CaO in the raw material reacts initially with SiO2, Al2O3, and Fe2O3 to generate low-melting-point minerals, and the material begins to agglomerate; the temperature of the firing zone is 1450-1550℃, which is the core reaction zone, where the main mineral C3S of the clinker is generated, and the material forms clinker particles with a particle size of 5-25mm; the temperature of the cooling zone is 1300-1000℃, and the clinker enters the cooling zone from the firing zone and is initially cooled by the cold air at the kiln tail.

6. The method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent as described in claim 1, characterized in that: The hot air temperature after heat exchange in S23 is 300-800℃, and it is divided into three parts: ① 600-800℃ hot air is sent to the decomposition furnace as secondary air, ② 300-400℃ hot air is sent to the preheater as tertiary air, ③ the remaining hot air is used for raw material drying or power generation, and the waste heat recovery rate is ≥70%.

7. A method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent as described in claim 1, characterized in that: When the cement type in S32 is P•I silicate cement, the batching composition is: 100% clinker and 3-5% gypsum, with no admixtures.

8. A method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent as described in claim 1, characterized in that: When the cement type in S32 is P•O ordinary Portland cement, the batching composition is: 70%-80% clinker, 3-5% gypsum, and 15-25% admixtures. The admixtures can be one or more of granulated blast furnace slag and fly ash.

9. A method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent as described in claim 1, characterized in that: The pretreatment process in S33 is as follows: the mixed material first enters the roller press and is squeezed into a cake by the high-pressure roller. More than 80% of the material in the cake has a particle size of ≤2mm.

10. A method for preparing low-carbon cement using a deactivated limestone-based calcium-based CO2 adsorbent as described in claim 1, characterized in that: The ball mill grinding process in S33 is as follows: the feed cake enters the ball mill for grinding and refining; the powder classification process involves the ball mill outlet material entering a high-efficiency powder classifier to separate qualified fine powder and coarse powder, with the coarse powder returned to the roller press or ball mill for regrinding; the specific surface area of ​​the qualified fine powder... ≤ 4% residue on 80μm sieve.

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