Preparation method of activated manganese slag and application of activated manganese slag in concrete for PHC pipe pile

Abstract

The invention discloses a preparation method of activated manganese slag and application of the activated manganese slag in concrete for a PHC pipe pile. The active manganese slag is prepared by mixing manganese slag, calcium oxide and silica fume, then carrying out ball milling treatment to prepare a composite precursor, and then dispersing the composite precursor in a sodium carbonate solution to carry out hydrothermal reaction; the active manganese slag is used for replacing 40-60% of cement to be used as a gel material for preparing the concrete for the PHC pipe pile. The prepared concrete is good in mechanical property, the amount of consumed manganese slag is large, high-value large-scale utilization of the manganese slag is effectively achieved, and remarkable economic benefits and environmental benefits are achieved.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization and concrete material technology, specifically involving a method for the synergistic preparation of activated manganese slag by mechanical force and hydrothermal method and the application of the activated manganese slag in PHC pipe pile concrete. Background Technology

[0002] Manganese slag is a high-temperature slag produced by ferroalloy enterprises during the smelting of silicon-manganese alloys in submerged arc furnaces. Its main chemical components are SiO2, CaO, and Al2O3, similar to those in cement. Therefore, activating and modifying manganese slag to prepare concrete materials is an important way to realize its resource utilization. However, the main mineral components of manganese slag have a dense crystalline structure, resulting in low chemical activity. This limits its direct replacement of cement in concrete materials, restricting not only its large-scale application but also its use in high-value materials such as PHC pipe piles.

[0003] Chinese patent application CN 115536302 B, authorized by CN 115536302 B, discloses an admixture for ultra-early strength shotcrete based on ferrosilicon slag and shotcrete itself. The patent discloses an admixture using ferrosilicon slag as the main raw material. While this patent discloses a method for preparing ultra-early strength shotcrete using ferrosilicon slag as an admixture, the amount of ferrosilicon slag-based admixture used is less than 20% of the cement dosage. The single chemical activation method does not fully activate the ferrosilicon slag and consumes a large amount of chemical reagents, resulting in a complex composition, increased cost, and hindering its large-scale promotion and application.

[0004] Chinese patent application CN 103755165 B discloses modified ferrosilicon manganese slag, concrete prepared using the ferrosilicon manganese slag, and a method for preparing the concrete. This method uses an organic salt activator to chemically activate the ferrosilicon manganese slag, and the ferrosilicon manganese slag content can reach 80% of the total mass of the cementitious materials. Although this invention has a high manganese slag utilization rate, the highest strength grade of the concrete tested still cannot replace the application of high-grade cement in high-value PHC pipe pile concrete materials; at the same time, the organic salts used are expensive, resulting in limited economic benefits. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing activated manganese slag and its application in PHC pipe pile concrete. The activated manganese slag is prepared using a mechanical-hydrothermal method. The resulting active material can largely replace cement in the preparation of PHC pipe pile concrete materials. The prepared PHC pipe pile concrete material has high activation efficiency, low energy consumption, and low reagent input cost.

[0006] To address the aforementioned technical problems, this invention provides a method for preparing activated manganese slag, the specific steps of which are as follows: S1. Manganese slag, calcium oxide and silica fume are mixed and then ball-milled in a ball mill to obtain a composite precursor; the mass ratio of manganese slag, calcium oxide and silica fume is 45-65 : 25-40 : 5-15. S2. Grind the composite precursor obtained in step S1 to a finer mesh than 100 mesh, then mix the finely ground composite precursor with sodium carbonate solution at a certain solid-liquid ratio, and carry out a hydrothermal reaction in a hydrothermal reactor. S3. After the reaction is complete, the hydrothermal product is dried and ground to a specific surface area ≥ 400 m². 2 / kg, to obtain the activated manganese slag.

[0007] The preferred technical solution of the present invention is as follows: In step S1, the ball milling speed is 100-500 rpm and the time is 1.0-5.0 h.

[0008] The preferred technical solution of the present invention is as follows: In step S1, the main chemical components and their mass percentages of the manganese slag are: 36.9-39.8% SiO2, 15.6-18.2% CaO, 11.3-12.5% ​​Al2O3, 8.5-10.6% MgO, 5.6-8.2% MnO, and 7.4-9.7% Fe2O3; the main chemical components and their mass percentages of the silica fume are: 92.0-98.0% SiO2.

[0009] A preferred embodiment of the present invention is that the solid-liquid ratio of the sodium carbonate solution to the composite precursor in step S2 is 100–300 kg / m³. 3 The sodium carbonate solution has a concentration of 0.05–0.2 mol / L, and the hydrothermal reaction is carried out at a temperature of 150–300 °C for 3.0–12.0 h.

[0010] The present invention also provides an application of the above-mentioned active manganese slag in PHC pipe pile concrete, wherein the above-mentioned active manganese slag replaces 40-60% of the cement as a cementing material in the preparation of PHC pipe pile concrete.

[0011] The preferred technical solution of the present invention is as follows: the cementitious material is composed of activated manganese slag, P·II 52.5R cement and activated activator in a mass ratio of 40-60: 35-50: 3-8.

[0012] The preferred technical solution of the present invention is as follows: the concrete for PHC pipe piles is prepared by mixing the following materials in parts by weight: 550-690 parts cementitious material, 110-150 parts water, 600-750 parts sand, 1100-1200 parts gravel, and 10-17 parts water-reducing agent.

[0013] The preferred technical solution of the present invention is that the active activator is Na2SiO3·9H2O.

[0014] The preferred technical solution of this invention is as follows: cementitious materials, water, sand, gravel and water-reducing agent are added to a mixer and mixed evenly, then poured into a mold, pre-cured in steam at 90-100 ℃ for 12 hours, then demolded and naturally cured for 3-7 days to obtain PHC pipe piles.

[0015] Beneficial effects of this invention: (1) The mechanical-hydrothermal synergistic activation process of manganese slag in this invention is simple, has high activation efficiency, low energy consumption, low reagent input cost, and the obtained active material can replace cement in large quantities for use in PHC pipe pile concrete materials, effectively maximizing the reuse of high-value manganese slag resources.

[0016] (2) The activated manganese slag prepared by this invention can save natural raw materials and reduce costs by replacing cement, and avoids the large amount of CO2 emissions in the cement industry production process. It has significant economic and environmental benefits and has broad market application prospects.

[0017] (3) The concrete prepared by this invention has good mechanical properties and its 28-day compressive strength can reach more than 80 MPa, which meets the requirement of the building pile technical specification (JGJ 94-2008) that the strength grade of PHC pipe pile concrete should not be lower than C80.

[0018] (4) This invention is particularly applicable to the fields of solid waste resource utilization and concrete material technology, and has important industrial application value. Attached Figure Description

[0019] Figure 1 This is a basic flowchart for preparing PHC concrete for pipe piles using a mechanical-hydrothermal synergistic activation method for manganese slag. Detailed Implementation

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0021] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0022] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0023] The manganese slag used in Examples 1-2 and Comparative Examples 1-4 was provided by a company in Guangxi. The main chemical components and contents are shown in Table 1.

[0024] Table 1. Main chemical components and content (%) of manganese slag

[0025] Example 1 provides a method for preparing activated manganese slag, comprising the following steps: S1. Manganese slag, calcium oxide and silica fume were mixed in a mass ratio of 50:40:10 and then treated in a ball mill at a speed of 400 rpm for 3.0 h to obtain a composite precursor. S2. After grinding the composite precursor to a finer mesh than 100 mesh, it is dispersed in a 0.1 mol / L sodium carbonate solution at a solid-liquid ratio of 200 kg / m3. Then, it is reacted in a hydrothermal reactor at 200 ℃ for 6 h. After filtration, drying and grinding, activated manganese slag A with a specific surface area of ​​432±26 m2 / kg is obtained.

[0026] Application Example 1: The activated manganese slag prepared in Example 1 was used to prepare concrete for PHC pipe piles. The specific steps are as follows: (1) Mix activated manganese slag A, P·II 52.5R cement and active activator evenly in a mass ratio of 50:45:5 to obtain cementitious material; (2) Add 650 parts of cementitious material, 130 parts of water, 700 parts of sand, 1150 parts of gravel and 12 parts of water-reducing agent to a mixer according to the mass ratio, mix thoroughly and evenly, pour into a mold, pre-cur in steam at 90-100 ℃ for 12 hours, remove the mold, and cure naturally for 7 days to obtain PHC pipe pile A.

[0027] Example 2 provides a method for preparing activated manganese slag, comprising the following steps: S1. Manganese slag, calcium oxide and silica fume were mixed in a mass ratio of 45:40:15 and then treated in a ball mill at a speed of 400 rpm for 5.0 h to obtain a composite precursor. S2. After grinding the composite precursor to a finer mesh than 100 mesh, adjust the solid-liquid ratio to 150 kg / m³. 3The sample was dispersed in a 0.05 mol / L sodium carbonate solution, then reacted in a hydrothermal reactor at 3000 ℃ for 6 h. After filtration, drying, and grinding, a sample with a specific surface area of ​​446±38 m² was obtained. 2 / kg of activated manganese slag B.

[0028] Application Example 2: The activated manganese slag prepared in Example 2 was used to prepare concrete for PHC pipe piles. The specific steps are as follows: (1) Mix activated manganese slag B, P·II 52.5R cement and active activator evenly in a mass ratio of 60:35:5 to obtain cementitious material; (2) Add 690 parts of cementitious material, 140 parts of water, 650 parts of sand, 1200 parts of gravel and 11 parts of water-reducing agent to a mixer according to the mass ratio, mix thoroughly and evenly, pour into a mold, pre-cur in steam at 90~100 ℃ for 12 hours, remove the mold, and cure naturally for 7 days to obtain PHC pipe pile B.

[0029] Example 3 provides a method for preparing activated manganese slag, comprising the following steps: S1. Manganese slag, calcium oxide and silica fume were mixed in a mass ratio of 60:35:5 and then treated in a ball mill at a speed of 500 rpm for 4.0 h to obtain a composite precursor. S2. After grinding the composite precursor to a finer mesh than 100 mesh, adjust the solid-liquid ratio to 100 kg / m³. 3 The sample was dispersed in a 0.1 mol / L sodium carbonate solution, then reacted in a hydrothermal reactor at 250 ℃ for 9 h. After filtration, drying, and grinding, a sample with a specific surface area of ​​414 ± 30 m² was obtained. 2 / kg of activated manganese slag C.

[0030] Application Example 3: The activated manganese slag prepared in Example 3 was used to prepare concrete for PHC pipe piles. The specific steps are as follows: (1) The activated manganese slag C, P·II 52.5R cement and the active activator are mixed evenly in a mass ratio of 40:52:8 to obtain a cementitious material; (2) Add 670 parts of cementitious material, 120 parts of water, 750 parts of sand, 1100 parts of gravel and 15 parts of water-reducing agent to a mixer according to the mass ratio, mix thoroughly and evenly, pour into a mold, pre-cur in steam at 90~100 ℃ for 12 hours, remove the mold, and cure naturally for 7 days to obtain PHC pipe pile C.

[0031] Comparative Example 1 The difference between this comparative example and Example 3 is that in step (1), the manganese slag, calcium oxide and silica fume were not ball-milled after mixing. The remaining steps were the same as in Example 3 to obtain activated manganese slag D. The activated manganese slag D prepared in Comparative Example 1 was then used to prepare PHC pipe piles D according to the steps in Example 3. Comparative Example 2 The difference between this comparative example and Example 3 is that the hydrothermal reaction in step (2) is not performed, and the remaining steps are the same as in Example 3 to obtain activated manganese slag E. The activated manganese slag E prepared in Comparative Example 2 is then used to prepare PHC pipe pile E according to the steps in Example 3.

[0032] Comparative Example 3 The difference between this comparative example and Example 3 is that no active activator is added in step (3), and the remaining steps are the same as in Example 3 to obtain active manganese slag F. The active manganese slag E prepared in Comparative Example 3 is used to prepare PHC pipe pile F according to the steps of Application Example 3.

[0033] Comparative Example 4 The difference between this comparative example and Example 3 is that ball milling and hydrothermal reaction treatment are not performed in steps (1) and (2), and no active activator is added in step (3). The remaining steps are the same as in Example 3, and active manganese slag G is obtained. The active manganese slag E prepared in Comparative Example 3 is used to prepare PHC pipe pile G according to the steps of Application Example 3.

[0034] Test Example 1 The PHC pipe piles prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests in accordance with GB / T 50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The results are shown in Table 2.

[0035] Table 2. Properties of concrete materials prepared in Examples 1-2 and Comparative Examples 1-4

[0036] As shown in the examples above, the PHC pipe pile concrete prepared by the mechanical-hydrothermal synergistic activation of manganese slag using the present invention exhibits excellent mechanical properties, with a 28-day compressive strength exceeding 80 MPa, meeting the requirement of a strength grade of not less than C80 for PHC pipe pile concrete in the Building Pile Technical Specification (JGJ94-2008). Comparative Examples 1-4 show that ball milling and hydrothermal reaction are the main factors affecting concrete strength, and therefore are key areas for optimization during operation. The amount of activated manganese slag replacing cement can reach up to 60%, and the concrete has a high capacity for manganese slag utilization. Therefore, the present invention has promising prospects for the harmless treatment and large-scale resource utilization of manganese slag.

[0037] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing activated manganese slag, characterized in that, The specific steps of the method are as follows: S1. Manganese slag, calcium oxide and silica fume are mixed and then ball-milled in a ball mill to obtain a composite precursor; the mass ratio of manganese slag, calcium oxide and silica fume is 45-65 : 25-40 : 5-15. S2. Grind the composite precursor obtained in step S1 to a finer mesh than 100 mesh, then mix the finely ground composite precursor with sodium carbonate solution at a certain solid-liquid ratio, and carry out a hydrothermal reaction in a hydrothermal reactor. S3. After the reaction is complete, the hydrothermal product is dried and ground to a specific surface area ≥ 400 m². 2 / kg, to obtain the activated manganese slag.

2. The method for preparing activated manganese slag according to claim 1, characterized in that: In step S1, the ball milling process is carried out at a rotation speed of 100–500 rpm for a time of 1.0–5.0 h.

3. The method for preparing activated manganese slag according to claim 1, characterized in that: In step S1, the main chemical composition and mass percentage of the manganese slag are: 36.9–39.8% SiO2, 15.6–18.2% CaO, 11.3–12.5% ​​Al2O3, 8.5–10.6% MgO, 5.6–8.2% MnO, and 7.4–9.7% Fe2O3; the main chemical composition and mass percentage of the silica fume are: 92.0–98.0% SiO2.

4. The method for preparing activated manganese slag according to claim 1, characterized in that: In step S2, the solid-liquid ratio of the sodium carbonate solution to the composite precursor is 100–300 kg / m³. 3 The sodium carbonate solution has a concentration of 0.05–0.2 mol / L, and the hydrothermal reaction is carried out at a temperature of 150–300 °C for 3.0–12.0 h.

5. The application of activated manganese slag prepared by the method as described in claims 1 to 4 in concrete for PHC pipe piles, characterized in that: The above-mentioned activated manganese slag was used to replace 40-60% of the cement as a cementing material in the preparation of PHC pipe pile concrete.

6. The application of activated manganese slag in PHC pipe pile concrete according to claim 5, characterized in that: The cementitious material is composed of activated manganese slag, P·II 52.5R cement and activated activator in a mass ratio of 40-60: 35-50: 3-8.

7. The application of activated manganese slag in PHC pipe pile concrete according to claim 6, characterized in that, The PHC pipe pile concrete is prepared by mixing the following materials in parts by weight: 550-690 parts cementitious material, 110-150 parts water, 600-750 parts sand, 1100-1200 parts gravel, and 10-17 parts water-reducing agent.

8. The application of activated manganese slag in PHC pipe pile concrete according to claim 6, characterized in that: The active activator is Na2SiO3·9H2O.

9. The application of activated manganese slag in PHC pipe pile concrete according to claim 7, characterized in that: After mixing the cementitious materials, water, sand, gravel, and water-reducing agent evenly in a mixer, the mixture is poured into a mold and pre-cured in steam at 90–100 °C for 12 hours. The mold is then removed, and the mixture is allowed to cure naturally for 3–7 days to obtain PHC pipe piles.

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