Preparation of magnesium slag-based lightweight high-strength thermal insulation materials and methods for synergistic CO2 fixation

Abstract

This invention belongs to the fields of flue gas treatment and industrial solid waste resource utilization, specifically relating to the preparation of magnesium slag-based lightweight high-strength thermal insulation materials and a method for synergistic CO2 fixation. The method uses magnesium slag as raw material, adds cement, foaming agent, and foam stabilizer, and after grouting and molding, introduces carbon dioxide gas to carry out a mineralization reaction in a carbonization reactor to obtain a lightweight high-strength thermal insulation material. Through the control of process parameters, the prepared thermal insulation material contains abundant fibrous aragonite-type calcium carbonate with a large aspect ratio, which plays a supporting role in the strength of the thermal insulation material, with a maximum compressive strength of up to 11.89 MPa. The method of this invention involves a simple process, mild conditions, high CO2 mineralization efficiency, and is easily industrialized.

Description

Technical Field

[0001] This invention belongs to the fields of flue gas treatment and industrial solid waste resource utilization, specifically involving the preparation of magnesium slag-based lightweight high-strength thermal insulation materials and a method for synergistic CO2 fixation. Background Technology

[0002] Magnesium slag is an industrial solid waste generated during the production of metallic magnesium. Currently, approximately 5.5 to 10 tons of magnesium slag are produced for every ton of metallic magnesium produced. Due to the high demand for magnesium, about 8 million tons of magnesium slag are generated annually. Magnesium slag has a pH value of around 12.45, and its main disposal methods are landfill and stockpiling, which not only consume land resources but also contribute to soil salinization. Some scholars have used magnesium slag as a desulfurizing agent in steelmaking or to replace some cement clinker, achieving some success, but its effective utilization has been limited by reaction conditions and process costs. As an alkaline industrial solid waste rich in calcium oxide and magnesium oxide, magnesium slag has high alkalinity and CO2 reactivity. Utilizing magnesium slag and other solid wastes for CO2 mineralization has significant environmental and economic advantages.

[0003] Carbon capture, storage, and utilization (CCSV) technology is an emerging technology for effectively capturing CO2 emissions from stationary sources such as thermal power, steel, cement, and chemical industries. Porous materials are considered the best choice for CO2 capture due to their large specific surface area, adjustable particle size and pore size, and modifiable surface. Currently, many researchers have developed a series of solid porous materials that can be used for CO2 absorption or adsorption, including zeolite materials, silicon-based adsorbents, carbon-based adsorbents, MOF materials, porous resins with supported catalysts, and other organic polymers.

[0004] A series of studies have been conducted on the carbon dioxide fixation of solid wastes such as magnesium slag. For example, patent CN116282116A discloses a recycling process for mineralizing carbon dioxide from magnesium slag. This involves crushing the magnesium slag, adding it to an ammonium chloride solution, heating it in a water bath to obtain a leachate and filter residue, and then introducing a carbon dioxide-containing gas into the leachate to stir and react, resulting in a precipitate and a reaction solution. This method indirectly mineralizes CO2 by extracting soluble alkaline components from the magnesium slag. However, the process requires numerous auxiliary reagents, is complex and cumbersome, and has high material consumption, limiting its application. Patent CN116265415A discloses a method for fixing carbon dioxide using silicon-calcium based solid waste. This method involves mixing raw materials such as steel slag with water, pressing them into blocks at 5–100 MPa, and then placing them in a reactor for a mineralization reaction. The pretreatment of the raw materials requires a systematic digestion process of 40 minutes before pressing into cakes. This method has a relatively cumbersome pretreatment process, and the prepared blocks have low CO2 mineralization efficiency. Therefore, it is necessary to develop a method for fixing CO2 by mineralizing solid waste, which is simple in process, low in energy and material consumption, and has high mineralization efficiency. Summary of the Invention

[0005] To address the problems of high energy and material consumption, complex and cumbersome processes, and low mineralization efficiency in existing solid waste mineralization and CO2 fixation technologies, this invention proposes a method for preparing a magnesium slag-based lightweight high-strength insulation material and synergistically fixing CO2. By controlling different reaction conditions and regulating the mineralization reaction performance, fibrous aragonite-type calcium carbonate is selectively generated to prepare a high-strength insulation material, realizing the resource utilization of magnesium slag and simultaneously achieving permanent carbon dioxide fixation, thus achieving the goal of "treating waste with waste".

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a magnesium slag-based lightweight high-strength thermal insulation material includes the following steps:

[0008] Step 1: Mix magnesium slag with cement, add water and stir to make a slurry;

[0009] Step 2: Add foaming agent and foam stabilizer to the slurry, stir evenly, pour into mold, and cure to form;

[0010] Step 3: After molding, CO2 gas is introduced to carry out a mineralization reaction, resulting in a lightweight and high-strength thermal insulation material;

[0011] Furthermore, in step 1, the water-to-solid mass ratio is 0.35 to 0.80, preferably 0.35 to 0.65.

[0012] Furthermore, in step 2, the foaming agent is at least one of sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and emulsifier OP-10.

[0013] Furthermore, in step 2, the foam stabilizer is at least one of tea saponin, plant protein, and calcium stearate.

[0014] Furthermore, in step 2, the amount of foaming agent is 2% to 10% of the total mass of magnesium slag and cement, and the amount of foam stabilizer is 0.010% to 0.025% of the total mass of magnesium slag and cement.

[0015] Furthermore, the curing conditions in step 2 are: 24 hours and 60°C.

[0016] Furthermore, the mineralization reaction conditions in step 3 are: CO2 volume concentration ≥ 40%, CO2 pressure 0.4~2.0MPa, temperature 120~180℃, and time 1~4h.

[0017] The magnesium slag-based lightweight high-strength thermal insulation material prepared by the preparation method described above has a length-to-diameter ratio of fibrous aragonite-type calcium carbonate of 9.0:1 to 18.8:1.

[0018] Furthermore, the porosity of the magnesium slag-based lightweight high-strength thermal insulation material is 4.14%–22.09%, the average pore size is 80.6 μm–128.4 μm, and the bulk density is 0.600 g / cm³. 3 ~1.500g / cm 3 The compressive strength is 2.23MPa~11.89MPa, and the thermal insulation coefficient is 0.15~0.29W / (m·K).

[0019] As previously described, the magnesium slag-based lightweight high-strength insulation material is used for permanent CO2 fixation and building insulation. The insulation material prepared by this invention contains a large number of channels and pores, resulting in a large specific surface area. This allows the magnesium slag to fully contact CO2 and undergo a mineralization reaction, thereby achieving permanent carbon dioxide fixation, promoting sustainable environmental development and efficient resource utilization.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention features low energy and material consumption, saving energy and raw materials and reducing costs; high mineralization efficiency, achieving permanent CO2 fixation, which is beneficial to environmental protection; a simple process, easy to implement in industrial production, facilitating rapid promotion and application; high-value utilization of solid waste, contributing to resource recycling and sustainable development; and significant environmental benefits and broad market prospects, making it a promising new technology for future development. Therefore, this invention is an innovative technology with broad application prospects and significant socio-economic benefits. Attached Figure Description

[0022] Figure 1 This is a production process flow diagram for magnesium slag-based lightweight high-strength thermal insulation materials.

[0023] Figure 2 This is a photograph of the magnesium slag-based lightweight high-strength thermal insulation material prepared in Example 1.

[0024] Figure 3 This is a SEM image of the magnesium slag-based lightweight high-strength thermal insulation material prepared in Example 1. Detailed Implementation

[0025] To facilitate understanding of the present invention, a more comprehensive description will be given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0026] In the following examples, PO 42.5 cement was selected, and the magnesium slag was naturally cooled magnesium slag from a magnesium smelting plant in Shaanxi Province, with a specific surface area of ​​324.7 m². 2 The chemical composition of the sample was determined by XRF analysis and is shown in Table 1.

[0027] Table 1. Elemental composition of magnesium slag (wt. / %)

[0028]

[0029] Example 1

[0030] Mix 90g of magnesium slag with 10g of cement, add 65mL of water, and stir at 500r / min for 0.5min. Add 2g of 10g / L sodium dodecyl sulfate solution and 0.015g of calcium stearate, and stir at 1500r / min for 2min. Pour the slurry into a mold, cure at 60℃ for 24h, and then demold. After demolding, transfer the mixture to a carbonization reactor, introduce 0.4MPa of 40% CO2, and perform a mineralization reaction at 120℃ for 2h to obtain the thermal insulation material.

[0031] Actual picture of the insulation material Figure 2 As shown, the SEM image is as follows: Figure 3 As shown.

[0032] The bulk density of the thermal insulation material is 1295 kg / m³. 3 The aragonite-type calcium carbonate has an aspect ratio of 9.6:1, a compressive strength of 11.89 MPa, a mineralization efficiency of 41.72%, a CO2 adsorption capacity of 375.5 kg / t, a porosity of 4.60%, an average pore size of 84.5 μm, and a thermal insulation coefficient of 0.28 W / (m·K).

[0033] Example 2

[0034] The specific implementation method of this embodiment is the same as that of embodiment 1, except that the foam stabilizer replaces 0.015g of tea saponin.

[0035] The bulk density of the thermal insulation material prepared in this embodiment is 1423 kg / m³. 3 The aragonite-type calcium carbonate has an aspect ratio of 9.0:1, a compressive strength of 10.06 MPa, a mineralization efficiency of 37.81%, a CO2 adsorption capacity of 340.3 kg / t, a porosity of 4.14%, an average pore size of 80.6 μm, and a thermal insulation coefficient of 0.29 W / (m·K).

[0036] Example 3

[0037] The specific implementation method of this embodiment is the same as that of embodiment 1, except that the foam stabilizer is replaced with 0.015g of plant protein.

[0038] The bulk density of the thermal insulation material prepared in this embodiment is 1390 kg / m³. 3The aragonite-type calcium carbonate has an aspect ratio of 9.4:1, a compressive strength of 11.25 MPa, a mineralization efficiency of 40.54%, a CO2 adsorption capacity of 364.9 kg / t, a porosity of 4.43%, an average pore size of 82.6 μm, and a thermal insulation coefficient of 0.28 W / (m·K).

[0039] Example 4

[0040] The specific implementation method of this embodiment is the same as that of embodiment 1, except that the foaming agent is replaced with 4g of 10g / L sodium dodecyl sulfate.

[0041] The bulk density of the thermal insulation material prepared in this embodiment is 1023 kg / m³. 3 The aragonite-type calcium carbonate has an aspect ratio of 10.8:1, a compressive strength of 8.56 MPa, a mineralization efficiency of 49.02%, a CO2 adsorption capacity of 441.1 kg / t, a porosity of 6.23%, an average pore size of 87.6 μm, and a thermal insulation coefficient of 0.24 W / (m·K).

[0042] Example 5

[0043] The specific implementation method of this embodiment is the same as that of embodiment 1, except that the foaming agent is replaced with 6g of 10g / L sodium dodecyl sulfate.

[0044] The bulk density of the thermal insulation material prepared in this embodiment is 850 kg / m³. 3 The aragonite-type calcium carbonate has an aspect ratio of 14.3:1, a compressive strength of 6.22 MPa, a mineralization efficiency of 55.93%, a CO2 adsorption capacity of 503.4 kg / t, a porosity of 12.63%, an average pore size of 98.1 μm, and a thermal insulation coefficient of 0.20 W / (m·K).

[0045] Example 6

[0046] The specific implementation method of this embodiment is the same as that of embodiment 1, except that the foaming agent is replaced with 8g of 10g / L sodium dodecyl sulfate.

[0047] The bulk density of the thermal insulation material prepared in this embodiment is 822 kg / m³. 3 The aragonite-type calcium carbonate has an aspect ratio of 17.2:1, a compressive strength of 4.04 MPa, a mineralization efficiency of 56.74%, a CO2 adsorption capacity of 510.7 kg / t, a porosity of 17.21%, an average pore size of 108.4 μm, and a thermal insulation coefficient of 0.18 W / (m·K).

[0048] Example 7

[0049] The specific implementation method of this embodiment is the same as that of embodiment 1, except that the foaming agent is replaced with 10g of 10g / L sodium dodecyl sulfate.

[0050] The bulk density of the thermal insulation material prepared in this embodiment is 661 kg / m³. 3 The aragonite-type calcium carbonate has an aspect ratio of 18.3:1, a compressive strength of 2.73 MPa, a mineralization efficiency of 59.08%, a CO2 adsorption capacity of 531.7 kg / t, a porosity of 21.76%, an average pore size of 122.4 μm, and a thermal insulation coefficient of 0.16 W / (m·K).

[0051] Example 8

[0052] The specific implementation method of this embodiment is the same as that of embodiment 1, except that the foaming agent is replaced with 10g / L hexadecyltrimethylammonium bromide.

[0053] The bulk density of the thermal insulation material prepared in this embodiment is 725 kg / m³. 3 The aragonite-type calcium carbonate has an aspect ratio of 17.8:1, a compressive strength of 2.23 MPa, a mineralization efficiency of 57.72%, a CO2 adsorption capacity of 519.5 kg / t, a porosity of 19.76%, an average pore size of 110.4 μm, and a thermal insulation coefficient of 0.17 W / (m·K).

[0054] Example 9

[0055] The specific implementation method of this embodiment is the same as that of embodiment 1, except that the foaming agent is replaced with 10g / L emulsifier OP-10.

[0056] The bulk density of the thermal insulation material prepared in this embodiment is 683 kg / m³. 3 The aragonite-type calcium carbonate has an aspect ratio of 18.1:1, a compressive strength of 2.49 MPa, a mineralization efficiency of 58.71%, and a CO2 adsorption capacity of 528.4 kg / t.

[0057] The porosity is 20.27%, the average pore size is 118.5 μm, and the thermal insulation coefficient is 0.16 W / (m·K).

[0058] Example 10

[0059] The specific implementation method of this embodiment is the same as that of embodiment 1, except that: the foaming agent is replaced with 10g of sodium dodecyl sulfate at a concentration of 10g / L, and the foam stabilizer is 0.010g of calcium stearate and 0.005g of tea saponin.

[0060] The bulk density of the thermal insulation material prepared in this embodiment is 610 kg / m³. 3The aragonite-type calcium carbonate has an aspect ratio of 18.8:1, a compressive strength of 2.60 MPa, a mineralization efficiency of 60.40%, a CO2 adsorption capacity of 540.4 kg / t, a porosity of 22.09%, an average pore size of 128.4 μm, and a thermal insulation coefficient of 0.15 W / (m·K).

[0061] The physicochemical properties of the thermal insulation materials prepared in Examples 1-10 above are shown in Table 2:

[0062] Table 2 Physicochemical properties of the thermal insulation materials prepared in Examples 1-10

[0063]

[0064]

[0065] The above description is only for better explaining the embodiments of the present invention and is not intended to limit them. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims

1. A method for preparing a magnesium slag-based lightweight high-strength thermal insulation material, characterized in that, Includes the following steps: Step 1: Mix magnesium slag and cement at a weight ratio of 90g:10g and add water to make a slurry; the water-to-solid mass ratio is 0.35~0.

80. Step 2: Add 2% to 10% of the total mass of magnesium slag and cement as foaming agent and 0.010% to 0.025% of the total mass of magnesium slag and cement as foam stabilizer to the slurry, stir evenly, pour into molds, and demold after curing. The foaming agent is at least one of sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and emulsifier OP-10; the foam stabilizer is at least one of tea saponin, plant protein, and calcium stearate. Step 3: After molding, CO2 gas is introduced, and a mineralization reaction is carried out at a temperature of 120~180℃ for 1~4 hours to permanently fix the carbon dioxide, obtaining a magnesium slag-based lightweight high-strength thermal insulation material; wherein the CO2 volume concentration is ≥40%, and the CO2 pressure is 0.4~2.0MPa; the aspect ratio of the fibrous aragonite-type calcium carbonate in the obtained magnesium slag-based lightweight high-strength thermal insulation material is (9.0~18.8):1, and the porosity of the magnesium slag-based lightweight high-strength thermal insulation material is 4.14%~22.09%, the average pore size is 80.6μm~128.4μm, and the bulk density is 0.600g / cm³. 3 ~1.500g / cm 3 The compressive strength is 2.23MPa~11.89MPa, and the thermal insulation coefficient is 0.15~0.29W / (m·K).

2. A magnesium slag-based lightweight high-strength thermal insulation material, characterized in that, The magnesium slag-based lightweight high-strength thermal insulation material is prepared by the preparation method described in claim 1.

3. The magnesium slag-based lightweight high-strength thermal insulation material according to claim 2, characterized in that, The magnesium slag-based lightweight high-strength thermal insulation material has a porosity of 4.14%~22.09%, an average pore size of 80.6μm~128.4μm, and a bulk density of 0.600g / cm³. 3 ~1.500g / cm 3 The compressive strength is 2.23MPa~11.89MPa, and the thermal insulation coefficient is 0.15~0.29W / (m·K).

4. The application of the magnesium slag-based lightweight high-strength thermal insulation material according to claim 2 or 3, characterized in that, Used for permanently fixing CO2 and building insulation materials.

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