High-CO2-fixed-amount high-strength carbonated product and preparation method thereof

Abstract

The invention provides a high-CO2-fixed-amount high-strength carbonated product and a preparation method thereof, and belongs to the technical field of building materials, and the preparation method comprises the following steps: carrying out primary grinding on a steel slag block to obtain coarse steel slag powder; adding water into the coarse steel slag powder, uniformly stirring, and carrying out one-time accelerated carbonation to obtain a carbonated crude product; performing secondary grinding on the carbonated crude product to obtain composite steel slag powder; adding water into the composite steel slag powder, uniformly stirring, pressing into a green body, and performing secondary accelerated carbonation curing on the green body to obtain a carbonated product. According to the present invention, the unreacted core in the carbonation crude product can be adopted as the template to perform the in-situ carbonation reaction when the secondary accelerated carbonation reaction is performed so as to provide the strong binding force between the secondary accelerated carbonation product and the primary accelerated carbonation product, such that the compressive strength of the steel slag carbonation product is ultimately improved; the carbonation product layer is damaged by grinding between two accelerated carbonation, and finally the overall CO2 fixing amount of the steel slag carbonation product is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and in particular relates to a high-CO2 fixed amount and high-strength carbonation product and a preparation method thereof. Background Art

[0002] Steel slag is a waste product in the steel production process. Every ton of crude steel produced produces 8% to 15% of steel slag. The amount of steel slag produced is large, the effective utilization rate is low, and large-scale storage is harmful to the environment. The main components of steel slag are calcium silicate, calcium ferrite, free calcium oxide and RO phase. Among them, calcium silicate and calcium oxide have extremely high carbonation activity. Using steel slag to capture CO2 and prepare carbonation products is a promising low-carbon technology.

[0003] However, the accelerated carbonation reaction of steel slag is a shrinking unreacted core model, and the dense product layer produced rapidly on the surface hinders the further diffusion reaction of CO2 into the particles, resulting in a low overall carbonation reaction degree of steel slag, low CO2 fixation, and low compressive strength of carbonated products. Prolonging the accelerated carbonation reaction time, increasing the accelerated carbonation reaction temperature and CO2 partial pressure can increase the CO2 diffusion depth and carbonation reaction degree to a certain extent, but the improvement is limited. Summary of the invention

[0004] In view of the technical problems existing in the background technology, the present application provides a high-strength carbonated product with high CO2 fixation and a preparation method thereof, aiming to solve the technical problems of low degree of carbonation reaction of steel slag, low CO2 fixation, and low compressive strength of carbonated products.

[0005] In a first aspect, the present invention provides a method for preparing a high-strength carbonated product with a high CO2 fixation amount, comprising the following steps: S1, grinding the steel slag block once to obtain a crude steel slag powder; S2, adding water to the crude steel slag powder and stirring evenly, and then performing an accelerated carbonation to obtain a carbonated crude product; S3, grinding the carbonated crude product for a second time to obtain composite steel slag powder, the specific surface area of ​​the composite steel slag powder is 500-600 m 2 / kg; S4. After adding water to the composite steel slag powder and stirring evenly, the mixture is pressed into a green body, and then the green body is subjected to secondary accelerated carbonation curing to obtain a carbonated product.

[0006] In some embodiments, the CO2 fixation amount of the crude carbonation product is 80-90 kg / t steel slag, and the CO2 fixation amount of the finished carbonation product is >150 kg / t steel slag.

[0007] In some embodiments, the mass ratio of water to crude steel slag powder is (0.15-0.2):1, and the mass ratio of water to composite steel slag powder is (0.08-0.13):1.

[0008] In some embodiments, the mass ratio of water to crude steel slag powder is (0.15-0.175):1, and the mass ratio of water to composite steel slag powder is (0.10-0.13):1.

[0009] In some embodiments, the specific surface area of ​​the crude steel slag powder is 200-300 m 2 / kg.

[0010] In some embodiments, the specific surface area of ​​the crude steel slag powder is 250-300 m 2 / kg.

[0011] In some embodiments, the specific surface area of ​​the composite steel slag powder is 550-600 m 2 / kg.

[0012] In some embodiments, the conditions for the first accelerated carbonation in step S2 are: CO2 volume concentration ≥ 99%, CO2 pressure 0.1 MPa, reaction time 30~60min, and reaction temperature at room temperature; the conditions for the second accelerated carbonation in step S4 are: CO2 volume concentration ≥ 99%, CO2 pressure 0.1~0.4MPa, reaction time ≥ 24h, and reaction temperature at room temperature.

[0013] In some embodiments, the conditions for the first accelerated carbonation in step S2 are: CO2 volume concentration ≥ 99%, CO2 pressure 0.1 MPa, reaction time 30~60 min, and reaction temperature at room temperature; the conditions for the second accelerated carbonation in step S4 are: CO2 volume concentration ≥ 99%, CO2 pressure 0.2~0.3 MPa, reaction time 48~72 h, and reaction temperature at room temperature.

[0014] In some embodiments, the pressure at which the green body is pressed in step S4 is 20-40 MPa.

[0015] In the second aspect, the embodiments of the present application provide a high-strength carbonated product with high CO2 fixation, wherein the CO2 fixation of the carbonated product is >150 kg / t steel slag and the compressive strength is >200 MPa.

[0016] In a third aspect, the embodiments of the present application provide a use of a high-CO2 fixed amount and high-strength carbonated product in the field of building materials.

[0017] Different from the existing technical solutions, the beneficial effects of this application include: 1. In this application, the crude steel slag powder is accelerated to undergo carbonation reaction and then ground to a specific surface area of ​​500-600 m 2 / kg of composite steel slag powder can destroy the dense product layer on the surface of the particles and expose the unreacted core in the crude steel slag powder; by controlling the CO2 fixation amount of the crude steel slag powder to 80~90 kg / t of steel slag, the crude steel slag powder after one accelerated carbonation reaction still has a higher carbonation activity, and the composite steel slag powder after re-crushing can improve the density of the green body. In addition, the unreacted core in the carbonated crude product can be used as a template for in-situ carbonation reaction after the second accelerated carbonation reaction, so that the binding force between the secondary accelerated carbonation product and the primary accelerated carbonation product is stronger, and finally the compressive strength of the steel slag carbonated product is improved. The grinding between the two accelerated carbonation reactions destroys the carbonated product layer, and finally the overall CO2 fixation amount of the steel slag carbonated product is improved.

[0018] 2. The results of the examples show that the high-CO2 fixation and high-strength carbonated product prepared by the preparation method provided in the present application has a CO2 fixation amount >150 kg / t of steel slag and a compressive strength >200 MPa.

[0019] 3. In addition, the preparation method of the carbonated product provided in the present application has a simple process, low grinding energy consumption, and a short maintenance period, and is a typical low-carbon technology.

[0020] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. DETAILED DESCRIPTION

[0021] The following is a detailed description of the embodiments of the technical solution of the present application. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0023] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0024] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0026] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0027] The accelerated carbonation reaction of steel slag is a shrinking unreacted core model. The dense product layer produced quickly on the surface hinders the further diffusion reaction of CO2 into the particles, resulting in a low overall carbonation reaction degree of steel slag, low CO2 fixation, and low compressive strength of carbonated products. Prolonging the accelerated carbonation reaction time, increasing the accelerated carbonation reaction temperature and CO2 partial pressure can increase the CO2 diffusion depth and carbonation reaction degree to a certain extent, but the improvement is limited.

[0028] In order to solve the technical problems of low carbonation reaction degree of steel slag, low CO2 fixation, and low compressive strength of carbonation products, the present application provides a high CO2 fixation and high-strength carbonation product and a preparation method thereof, wherein the carbonation reaction of crude steel slag powder is accelerated and then ground to a specific surface area of ​​500-600 m 2 / kg of composite steel slag powder can destroy the dense product layer on the surface of the particles and expose the unreacted core in the crude steel slag powder; by controlling the CO2 fixation amount of the crude steel slag powder to 80~90 kg / t of steel slag, the crude steel slag powder after one accelerated carbonation reaction still has a higher carbonation activity, and the composite steel slag powder after re-crushing can improve the density of the green body. In addition, the unreacted core in the carbonated crude product can be used as a template for in-situ carbonation reaction after the second accelerated carbonation reaction, so that the binding force between the secondary accelerated carbonation product and the primary accelerated carbonation product is stronger, and finally the compressive strength of the steel slag carbonated product is improved. The grinding between the two accelerated carbonation reactions destroys the carbonated product layer, and finally the overall CO2 fixation amount of the steel slag carbonated product is improved.

[0029] In a first aspect, the present invention provides a method for preparing a high-strength carbonated product with a high CO2 fixation amount, comprising the following steps: S1, grinding the steel slag block once to obtain a crude steel slag powder; S2, adding water to the crude steel slag powder and stirring evenly, and then performing an accelerated carbonation to obtain a carbonated crude product; S3, grinding the carbonated crude product for a second time to obtain composite steel slag powder, the specific surface area of ​​the composite steel slag powder is 500-600 m 2 / kg; S4. After adding water to the composite steel slag powder and stirring evenly, the mixture is pressed into a green body, and then the green body is subjected to secondary accelerated carbonation curing to obtain a carbonated product.

[0030] In some embodiments, the CO2 fixation amount of the crude carbonation product is 80-90 kg / t steel slag, and the CO2 fixation amount of the finished carbonation product is >150 kg / t steel slag.

[0031] In the technical solution of the embodiment of the present application, the grinding equipment in the present application is preferably a ball mill, and the grinding time is used to control the fineness of the powder. The present application does not specifically limit the grinding process, and the grinding process well known in the art is used to make the specific surface area of ​​the crude steel slag powder and the composite steel slag powder meet the requirements. In the present application, the main components of the steel slag block include calcium silicate, calcium ferrite, calcium oxide and RO phase.

[0032] In some embodiments, the mass ratio of water to crude steel slag powder is (0.15-0.2):1, and the mass ratio of water to composite steel slag powder is (0.08-0.13):1.

[0033] In some embodiments, the mass ratio of water to crude steel slag powder is (0.15-0.175):1, and the mass ratio of water to composite steel slag powder is (0.10-0.13):1.

[0034] In the technical solution of the embodiment of the present application, the process of stirring and mixing the crude steel slag powder, the composite steel slag powder and water in the present application is not particularly limited, and the materials can be evenly mixed by a stirring process well known in the art.

[0035] In some embodiments, the specific surface area of ​​the crude steel slag powder is 200-300 m 2 / kg.

[0036] In some embodiments, the specific surface area of ​​the crude steel slag powder is 250-300 m 2 / kg In some embodiments, the specific surface area of ​​the composite steel slag powder is 550-600 m 2 / kg.

[0037] In some embodiments, the conditions for the first accelerated carbonation in step S2 are: CO2 volume concentration ≥ 99%, CO2 pressure 0.1 MPa, reaction time 30~60min, and reaction temperature at room temperature; the conditions for the second accelerated carbonation in step S4 are: CO2 volume concentration ≥ 99%, CO2 pressure 0.1~0.4MPa, reaction time ≥ 24h, and reaction temperature at room temperature.

[0038] In some embodiments, the conditions for the first accelerated carbonation in step S2 are: CO2 volume concentration ≥ 99%, CO2 pressure 0.1 MPa, reaction time 30~60 min, and reaction temperature at room temperature; the conditions for the second accelerated carbonation in step S4 are: CO2 volume concentration ≥ 99%, CO2 pressure 0.2~0.3 MPa, reaction time 48~72 h, and reaction temperature at room temperature.

[0039] In some embodiments, the pressure at which the green body is pressed in step S4 is 20-40 MPa.

[0040] In the second aspect, the embodiments of the present application provide a high-strength carbonated product with high CO2 fixation, wherein the CO2 fixation of the carbonated product is >150 kg / t of steel slag and the compressive strength is >200 MPa.

[0041] In a third aspect, the embodiments of the present application provide a use of a high-CO2 fixed amount and high-strength carbonated product in the field of building materials.

[0042] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0043] 1. Preparation method Embodiment 1~6 The steel slag block is ball milled to a specific surface area of ​​200-300 m 2 / kg of crude steel slag powder; after adding water to the crude steel slag powder and mixing it evenly, perform an accelerated carbonation (CO2 pressure 0.1MPa) for 30-60 min until the CO2 fixed amount is 80-90 kg / t of steel slag; grind the crude steel slag powder after the accelerated carbonation to a specific surface area of ​​500-600 m 2 / kg of composite steel slag powder.

[0044] The composite steel slag powder is mixed with water evenly, and the mass ratio of water to composite steel slag powder is 0.10:1; then it is pressed into a product body, and the pressing pressure is 30 MPa; finally, the body is placed in a closed container with a CO2 concentration of 99% and a CO2 pressure of 0.3 MPa to accelerate the carbonation reaction for 48 hours to obtain a steel slag carbonated product.

[0045] According to the GB / T17671-1999 cement mortar strength test, the compressive strength test of the steel slag carbonated products prepared in Examples 1 to 6 was carried out, and the CO2 fixation amount was calculated using the mass increase before and after carbonation. The specific parameters and performance indicators of Examples 1 to 6 are shown in Table 1.

[0046] Table 1 Specific parameters and performance indicators of the carbonated products prepared in Examples 1 to 6

[0047] It can be seen from Table 1 that the CO2 fixation amount of the steel slag carbonation products prepared in Examples 1 to 6 of the present invention is >150 kg / t steel slag, and the compressive strength is >200 MPa.

[0048] Embodiments 7 to 12 The steel slag block was ball milled to a specific surface area of ​​245 m 2 / kg crude steel slag powder; the crude steel slag powder was mixed with water (the mass ratio of water to crude steel slag powder was 0.175) and then subjected to an accelerated carbonation (CO2 pressure 0.1MPa) for 45 min until the CO2 fixed amount was 86 kg / t steel slag; the crude steel slag powder after the accelerated carbonation was ground to a specific surface area of ​​587 m 2 / kg of composite steel slag powder.

[0049] The composite steel slag powder is mixed with water evenly, and the mass ratio of water to the composite steel slag powder is (0.08~0.13) : 1; then it is pressed into a product body, and the pressing pressure is 20~40 MPa; finally, the body is placed in a closed container with a CO2 concentration of 99% and a CO2 pressure of 0.1~0.4 MPa for secondary accelerated carbonation reaction, and the reaction time is >24h to obtain a steel slag carbonated product.

[0050] According to the GB / T17671-1999 cement mortar strength test, the compressive strength test of the steel slag carbonated products prepared in Examples 7 to 11 was carried out, and the CO2 fixation amount was calculated using the mass increase before and after carbonation. The specific parameters and performance indicators of Examples 7 to 12 are shown in Table 2.

[0051] Table 2 Specific parameters and performance indicators of the carbonated products prepared in Examples 7 to 12

[0052] It can be seen from Table 2 that the CO2 fixation amount of the steel slag carbonation products prepared in Examples 7 to 12 of the present invention is >150 kg / t steel slag, and the compressive strength is >200 MPa.

[0053] Comparative Example 1 The steel slag block was ball milled to a specific surface area of ​​245 m 2 / kg crude steel slag powder; the crude steel slag powder was mixed with water (the mass ratio of water to crude steel slag powder was 0.175) and then subjected to an accelerated carbonation (CO2 pressure 0.1MPa) for 120 min until the CO2 fixed amount was 105 kg / t steel slag; the crude steel slag powder after the accelerated carbonation was ground to a specific surface area of ​​593 m 2 / kg of composite steel slag powder. The composite steel slag powder is mixed with water, and the mass ratio of water to the composite steel slag powder is 0.1:1; then it is pressed and formed into a product body, and the pressing pressure is 30 MPa; finally, the body is placed in a closed container with a CO2 concentration of 99% and a CO2 pressure of 0.2 MPa for secondary accelerated carbonation reaction, and the reaction time is 48 hours to obtain a steel slag carbonated product. According to the GB / T17671-1999 cement mortar strength test, the compressive strength test of the steel slag carbonated product prepared in Comparative Example 1 was carried out, and the CO2 fixation amount was calculated by the mass increase before and after carbonation. Since the CO2 fixation amount of crude steel slag is too large, the CO2 fixation amount of the steel slag carbonated product prepared in Comparative Example 1 of the present application is 143 kg / t steel slag, which is less than 150 kg / t steel slag, and the compressive strength is 182 MPa, which is less than 200 MPa.

[0054] Comparative Example 2 The steel slag block was ball milled to a specific surface area of ​​245 m 2 / kg of crude steel slag powder; the crude steel slag powder was mixed with water (the mass ratio of water to crude steel slag powder was 0.175) and then subjected to accelerated carbonation (CO2 pressure 0.1MPa) for 20 min until the CO2 fixed amount was 51 kg / t steel slag; the crude steel slag powder after accelerated carbonation was ground to a specific surface area of ​​517 m 2 / kg of composite steel slag powder. The composite steel slag powder is mixed with water, and the mass ratio of water to the composite steel slag powder is 0.1:1; then it is pressed and formed into a product body, and the pressing pressure is 30 MPa; finally, the body is placed in a closed container with a CO2 concentration of 99% and a CO2 pressure of 0.2 MPa for secondary accelerated carbonation reaction, and the reaction time is 48 hours to obtain a steel slag carbonated product. According to the GB / T17671-1999 cement mortar strength test, the compressive strength test of the steel slag carbonated product prepared in Comparative Example 2 was carried out, and the CO2 fixation amount was calculated by the mass increase before and after carbonation. Since the CO2 fixation amount of crude steel slag is too low, the CO2 fixation amount of the steel slag carbonated product prepared in Comparative Example 2 of the present application is 129 kg / t steel slag, which is less than 150 kg / t steel slag, and the compressive strength is 152MPa, which is less than 200MPa.

[0055] Comparative Example 3 Grind the steel slag to a specific surface area of ​​245 m 2 / kg of crude steel slag powder; the crude steel slag powder is mixed with water (the mass ratio of water to crude steel slag powder is 0.1) and then pressed into a product body at a pressing pressure of 30 MPa; finally, the body is placed in a closed container with a CO2 concentration of 99% and a CO2 pressure of 0.2 MPa for an accelerated carbonation reaction, and the reaction time is 48 hours to obtain a steel slag carbonated product. According to the GB / T17671-1999 cement mortar strength test, the compressive strength test of the steel slag product prepared in Comparative Example 3 was carried out, and the CO2 fixation amount was calculated by the mass increase before and after carbonation. Due to the excessive CO2 fixation amount of crude steel slag, the CO2 fixation amount of the steel slag product prepared in Comparative Example 3 of the present application is 96 kg / t steel slag, which is less than 150 kg / t steel slag, and the compressive strength is 131 MPa, which is less than 200 MPa.

[0056] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing a high-strength carbonated product with high CO2 fixation, characterized in that: The following steps are involved: S1, grinding the steel slag block once to obtain a crude steel slag powder; S2, adding water to the crude steel slag powder and stirring evenly, and then performing an accelerated carbonation to obtain a carbonated crude product; S3, grinding the carbonated crude product for a second time to obtain composite steel slag powder, wherein the composite steel slag powder has a specific surface area of ​​500-600 m 2 / kg; S4, adding water to the composite steel slag powder and stirring evenly, pressing the composite steel slag powder into a green body, and then subjecting the green body to secondary accelerated carbonation curing to obtain a carbonated product.

2. The method for preparing a high-strength carbonated product with high CO2 fixation according to claim 1, characterized in that: The CO2 fixation amount of the carbonation crude product is 80-90 kg / t steel slag, and the CO2 fixation amount of the carbonation product is greater than 150 kg / t steel slag.

3. The method for preparing a high-strength carbonated product with high CO2 fixation according to claim 1, characterized in that: The mass ratio of the water to the crude steel slag powder is (0.15-0.2):1, and the mass ratio of the water to the composite steel slag powder is (0.08-0.13):

1.

4. The method for preparing a high-strength carbonated product with high CO2 fixation according to claim 1, characterized in that: The mass ratio of the water to the crude steel slag powder is (0.15-0.175):1, and the mass ratio of the water to the composite steel slag powder is (0.10-0.13):

1.

5. The method for preparing a high-strength carbonated product with high CO2 fixation according to claim 1, characterized in that: The specific surface area of ​​the crude steel slag powder is 200-300 m 2 / kg.

6. The method for preparing a high-strength carbonated product with high CO2 fixation according to claim 1, characterized in that: The conditions for accelerating carbonation in step S2 are: CO2 volume concentration ≥ 99%, pressure 0.1 MPa, reaction time 30-60 min, and reaction temperature normal temperature; The conditions for the secondary accelerated carbonation in step S4 are: CO2 volume concentration ≥ 99%, CO2 pressure 0.1-0.4 MPa, reaction time ≥ 24 h, and reaction temperature is room temperature.

7. The method for preparing a high-strength carbonated product with high CO2 fixation according to claim 1, characterized in that: The conditions for accelerating carbonation in step S2 are: CO2 volume concentration ≥ 99%, pressure 0.1 MPa, reaction time 30-60 min, and reaction temperature normal temperature; The conditions for the secondary accelerated carbonation in step S4 are: CO2 volume concentration ≥ 99%, CO2 pressure 0.2-0.3MPa, reaction time 48-72h, and reaction temperature is room temperature.

8. The method for preparing a high-strength carbonated product with high CO2 fixation according to claim 1, characterized in that: The pressure for pressing the green body in step S4 is 20-40 MPa.

9. A high-CO2 fixed amount and high-strength carbonated product, characterized in that: The carbonated product is prepared by the method for preparing a high-strength carbonated product with high CO2 fixation as described in any one of claims 1 to 8, wherein the CO2 fixation of the carbonated product is >150 kg / t slag and the compressive strength is >200 MPa.

10. Use of a high CO2 fixation and high strength carbonated product according to any one of claims 1 to 8 in the field of building materials.

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