Building material prepared by combining carbonation of magnesium slag with gasification slag and method thereof

Abstract

The invention discloses a building material prepared by combining carbonation of magnesium slag with gasification slag and a method for preparing the building material. The method comprises the following steps: step 1, drying a magnesium slag raw material, crushing the magnesium slag raw material by a jaw crusher, and grinding the crushed magnesium slag raw material into fine powder by a ball mill to serve as matrix fine powder; 2, after being dried, the gasification furnace slag raw material is crushed through a jaw crusher and screened according to a certain particle level to serve as aggregate; 3, sequentially adding the aggregate, the binding agent and the matrix fine powder, mixing, and ageing in a closed container or a plastic bag; step 4, performing compression molding on the ageing-aged material by adopting a semi-dry method, and naturally airing; 5, the aired sample is put into carbonation equipment for sample carbonation treatment, and the building material prepared through combination of magnesium slag carbonation and gasification slag is obtained. According to the invention, reaction combination is realized, so that the material has relatively high compressive strength.

Description

Technical Field

[0001] The present invention belongs to the technical field of comprehensive utilization of solid waste and building materials, and particularly relates to a method for preparing building materials by utilizing carbonation of magnesium slag combined with gasification furnace slag. Background Art

[0002] In traditional building material production, the large amount of cement used requires high-temperature calcination, resulting in high energy consumption, high carbon emissions, and irreversible damage to the environment. To address these issues, the synergistic production of new building materials using coal gasification slag, coal gangue, magnesium slag, and CO2 has become a viable green development approach, achieving resource recycling.

[0003] Gasifier slag is a solid waste produced during the coal gasification process. It contains active components capable of participating in pozzolanic reactions, but its high carbon content limits its application. Magnesium reduction slag is a solid waste discharged during the magnesium production process. The presence of highly hydrating free calcium oxide (f-CaO) and free magnesium oxide (f-MgO) in magnesium slag causes rapid reactions during hydration, resulting in internal volume expansion and destruction of structural integrity, ultimately affecting the volume stability of the hydrated product. Furthermore, the low hydration activity of γ-C2S further slows the overall hydration rate of magnesium slag.

[0004] These are the main reasons why magnesium slag is difficult to utilize on a large scale. Summary of the Invention

[0005] In order to overcome the defects of the above prior art, the purpose of the present invention is to provide a method for preparing building materials by carbonation of magnesium slag combined with gasification slag, wherein the method generates CO2 and dissolves it in water to generate carbonate solution. Under appropriate temperature and gas flow rate, Ca 2+ and Mg 2+ Plasma in CO3 2- The accelerated diffusion rate in the environment promotes the carbonation reaction between the carbonate solution and the free magnesium oxide and Ca2SiO4 in the sample to generate magnesium carbonate, calcite and aragonite, achieving reaction bonding, thereby giving the material higher compressive strength.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing building materials by utilizing carbonation of magnesium slag combined with gasification furnace slag comprises the following steps:

[0008] Step 1: drying the magnesium slag raw material, crushing it with a jaw crusher, and then grinding it into fine powder with a ball mill to serve as the matrix fine powder;

[0009] Step 2: drying the gasification slag raw material, crushing it with a jaw crusher, and screening it according to a certain particle size to use as aggregate;

[0010] Step 3, adding the aggregate, binder and matrix powder in sequence, mixing and placing in a sealed container or plastic bag for drying;

[0011] Step 4: the scalded material is pressed into shape using a semi-dry method and then naturally aired;

[0012] Step 5: Place the air-dried sample into a carbonation device for sample carbonation treatment, so as to obtain magnesium slag carbonation combined with gasification furnace slag to prepare building materials.

[0013] In step 1, the magnesium slag is dried in an oven at 90-120°C for 24-48 hours, and then ball-milled for 30-120 minutes. The fine powder after ball milling has a particle size of 0.05-100 μm, which can stimulate most of the potential gelling reactivity of the magnesium slag.

[0014] In step 2, the gasification slag raw material must be dried in an oven at 90° C.-110° C. for 24 h-48 h.

[0015] In step 2, the fumed slag, crushed by the jaw crusher, is screened into particle sizes of 1-3 mm and 0.5-3 mm. The goal is to select aggregates with a larger particle size range to fully utilize the fumed slag raw material. Furthermore, by optimizing the gradation design, high density and excellent mechanical properties of the material can be achieved.

[0016] In step 3, in order to fully utilize the gasification slag raw material, the ratio of aggregate to matrix powder is between (30-50): (50-70), and the binder accounts for 10-20% of the total weight of the aggregate and matrix powder (the mechanical properties of the sample are good within this range).

[0017] In the step 3, the binder dilution solution is first added to the aggregate and mixed for 3 to 5 minutes, and then the matrix powder is added and mixed for 3 to 5 minutes. The total mixing time in the wheel mill is 10 to 20 minutes.

[0018] In step 3, the curing time is 2 to 6 hours, so that the binder is more evenly distributed and easy to shape.

[0019] In the step 4, the bricks are pressed into a certain shape and size, and brick presses of different tonnages are used according to the size of the bricks.

[0020] In step 4, the drying time is half a day to 1 day.

[0021] In step 5, the sample is carbonated in a controllable carbonation device. The carbonation device is first heated to 40° C. to 70° C., and carbonation can be performed when the temperature reaches this range.

[0022] CO2 enters the equipment through the bubbling method, and the CO2 flow rate is controlled to ensure that the calcium carbonate generated by the carbonation reaction reacts completely. The temperature of the carbonation equipment is stable at 40℃~70℃, the volume fraction of CO2 in the CO2 gas is 50%~99%, the CO2 flow rate is 2L / min~6L / min, and the carbonation time is 1 day to 7 days. The sample is subjected to carbonation reaction under the above conditions to obtain a building material with higher strength.

[0023] A building material prepared by carbonating magnesium slag in combination with gasification slag, comprising CaCO3, which covers the surface of uncarbonized hydration products and C2S particles, and fills and connects the matrix and aggregate around the C2S. The presence of CaCO3 causes the three to mix together, thereby densifying the matrix.

[0024] The CaCO3 is coated with C2S, periclase and ferrosilicon, and the contents of periclase and ferrosilicon are lower than that of C2S.

[0025] Beneficial effects of the present invention:

[0026] This invention solidifies solid waste resources and reduces CO2 emissions by introducing CO2 from flue gas, effectively solving the problem of utilizing CO2 from industrial solid waste and flue gas. The main raw materials used in this invention are magnesium slag as the matrix and solid wastes such as gasification furnace slag, coal gangue, construction waste bricks, and waste concrete as aggregates. This method is inexpensive and significantly increases the utilization rate of solid wastes such as magnesium slag and gasification furnace slag, offering a high cost-effectiveness ratio.

[0027] At the same time, since gasification furnace slag, coal gangue, etc. replace natural aggregates such as sand and stone as raw materials for concrete, the mining and use of natural sand and gravel aggregates are greatly reduced, which can effectively protect mines, save natural resources, and provide a sustainable development method for the concrete construction industry. The magnesium slag used can replace the raw materials of cement, reducing the amount of cement used, saving energy and reducing carbon emissions. The method has the characteristics of simple steps and easy operation, and the raw materials are easy to obtain and do not require maintenance, which can reduce energy consumption and is easy to carry out on a large scale. Wastes such as gasification furnace slag can be selected as aggregates according to different usage scenarios, and the particle size range of different raw materials can be selected, so that the product performance has a large adjustable range. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the phase composition of the raw materials.

[0029] Figure 2Schematic diagram of the phase composition of the product of Example 1.

[0030] Figure 3 Schematic diagram of the microstructure of the product of Example 1.

[0031] Figure 4 Schematic diagram of the microstructure of the product of Example 2.

[0032] Figure 5 Schematic diagram of the microstructure of the product of Example 3.

[0033] Figure 6 Schematic diagram of the microstructure of the product of Example 4. DETAILED DESCRIPTION

[0034] The present invention will be described in further detail below with reference to the accompanying drawings.

[0035] A method for preparing building materials by combining carbonation of magnesium slag with gasification slag, comprising the following steps:

[0036] a. Abrasive: After drying, magnesium slag and gasification furnace slag are crushed by a jaw crusher; the crushed magnesium slag is then ground into fine powder by a ball mill and a planetary ball mill. The ball-milled magnesium slag fine powder is used as the matrix fine powder.

[0037] In the present invention, the ball milling time is 120 minutes, the planetary ball milling time is 0 minutes to 90 minutes, and the particle size of the fine powder after ball milling is 3 to 8 μm.

[0038] b. Screening: The dried and crushed gasification furnace slag, coal gangue, etc. are screened according to the particle size of 1-3mm and 0.5-3mm as aggregate.

[0039] c. Mixing: First, add the binder diluent to the aggregate and mix for 3-5 minutes. Then, add the matrix powder and mix for 3-5 minutes. The total mixing time in the roller mill is 10-20 minutes. The weight ratio of aggregate to matrix powder should be between (30-50): (50-70).

[0040] d. Curing: After mixing, place the mixed materials in a sealed container or plastic bag and curing for 2 to 6 hours to make the binder more evenly distributed and easier to shape.

[0041] e. Molding: Use a hydraulic press to press the above-mentioned slurry into a cylindrical sample of Φ36×36, and the molding pressure is 80~150MPa.

[0042] f. Drying: Let the formed sample dry naturally for half a day to one day.

[0043] g. CO2 Carbonation: Place the air-dried sample into a CO2 carbonation apparatus and introduce CO2 into the apparatus by bubbling. Maintain the carbonation apparatus at 40-70°C for 1-7 days at a CO2 flow rate of 2-6 L / min. The volume fraction of CO2 in the CO2 gas should be 50%-99%. Preferably, maintain the temperature at 60°C for 1 day. Remove the sample after carbonation.

[0044] The magnesium slag carbonation combined with gasification slag building material prepared by the present invention has the characteristics of high compressive strength, readily available raw materials, low cost, and simple and convenient production. The following are several preferred embodiments of the present invention, but the present invention is not limited to these embodiments. Experiments by the applicant have shown that the magnesium slag carbonation combined with gasification slag building material can be prepared within the scope of the present invention.

[0045] Example 1:

[0046] The chemical composition of the raw materials magnesium slag and gasification furnace slag is shown in Table 1, and the phase composition is shown in Figure 1 shown.

[0047] From the attached Figure 1 It can be seen that the main mineral components of magnesium slag are γ-C2S and β-C2S, as well as periclase and calcium iron oxide compounds; the main crystal phase of gasification furnace slag is quartz, and there are amorphous cells, indicating that the content of amorphous phase is high.

[0048] Table 1 Chemical composition of raw materials (wt%)

[0049]

[0050] The 1-3 mm gasification furnace slag is used as the aggregate part and the magnesium slag fine powder is used as the matrix part, and the ratio of coarse particles to fine powder is 40:60. The amount of binder added is 16%. After the ingredients are fully mixed, they are formed on a hydraulic press with a molding pressure of 150 MPa. The sample is naturally dried for 1 day. The dried sample is placed in a carbonation box, and a CO2 flow is introduced. It is heated to 60°C to start carbonation. The CO2 flow rate is 4L / min. Carbonation is carried out for 1 day to obtain magnesium slag carbonation combined with gasification furnace slag building materials. The physical composition of the sample is as follows Figure 2 As shown, the microstructure Figure 3 The performance is shown in Table 2.

[0051] From the attached Figure 2 It can be seen that new phases calcite and aragonite are generated after the sample is carbonated. At the same time, the main crystal peak intensity of γ-C2S and β-C2S is slightly lower than that of the main crystal peak intensity of calcite.

[0052] From the attached Figure 3It can be seen that periclase has clearly undergone carbonation. Observing the EDS spectra around and within the C2S in the yellow box, CaCO3 forms a thick ring structure of product layers around the C2S, and obvious reaction signs are also observed within the C2S.

[0053] The building material is attached Figure 3 Analysis of the SEM image and corresponding EDS spectrum reveals that the light gray phase is C2S, the dark gray phase is periclase, the white phase is ferrosilicon, and the gray phase is actually CaCO3. CaCO3 is widely distributed, enveloping C2S, periclase, and ferrosilicon, with the periclase and ferrosilicon content being relatively low relative to C2S. These phases can be identified through SEM and EDS analysis, with the periclase clearly undergoing carbonation.

[0054] Table 2 Performance of magnesium slag carbonation combined with gasification furnace slag building materials corresponding to Example 1

[0055]

[0056] Example 2:

[0057] The 1-3 mm gasification furnace slag is used as the aggregate part and the magnesium slag fine powder is used as the matrix part, and the ratio of coarse particles to fine powder is 40:60. The binder is added in an amount of 16%. After the ingredients are fully mixed, they are formed on a hydraulic press with a molding pressure of 150 MPa. The sample is naturally dried for 1 day, and the dried sample is placed in a carbonation box. A CO2 flow is introduced, and the carbonation is started at 60°C with a CO2 flow rate of 2 L / min. The carbonation is carried out for 1 day to obtain magnesium slag carbonation combined with gasification furnace slag building materials. The microstructure and properties of the sample are shown in FIG. Figure 4 and shown in Table 3.

[0058] From the attached Figure 4 It can be seen that CaCO3 grows and covers the surface of uncarbonized hydration products and C2S particles. The presence of CaCO3 makes the three mixed together, thereby densifying the matrix.

[0059] Table 3 Performance of magnesium slag carbonation combined with gasification furnace slag building materials corresponding to Example 2

[0060]

[0061] Example 3:

[0062] The 0.5-3mm coal gangue is used as the aggregate part and the magnesium slag fine powder is used as the matrix part, and the ratio of coarse particles to fine powder is 50:50. The binder is added in an amount of 16%. After the ingredients are fully mixed, they are formed on a hydraulic press with a molding pressure of 150MPa. The sample is naturally dried for half a day to 1 day. The dried sample is placed in a carbonation box, and a CO2 air flow is introduced. It is heated to 60°C to start carbonation. The CO2 flow rate is 4L / min. Carbonation is carried out for 1 day to obtain magnesium slag carbonated coal gangue building materials. The microstructure and properties of the sample are shown in Figure 2. Figure 5 and as shown in Table 4.

[0063] From the attached Figure 5 It can be seen that CaCO3 is widely distributed, wrapped in C2S, periclase and ferrosilicon, and the content of periclase and ferrosilicon is lower than that of C2S.

[0064] Table 4 Performance of magnesium slag carbonation combined with coal gangue building materials corresponding to Example 3

[0065]

[0066] Example 4:

[0067] The 1-3 mm gasification furnace slag is used as the aggregate part and the magnesium slag fine powder is used as the matrix part, and the ratio of coarse particles to fine powder is 40:60. The binder is added in an amount of 16%. After the ingredients are fully mixed, they are formed on a hydraulic press with a molding pressure of 150 MPa. The sample is naturally dried for half a day to 1 day. The dried sample is placed in a carbonation box, and a CO2 flow is introduced. It is heated to 60°C to start carbonation. The CO2 flow rate is 4L / min. The carbonation is carried out for 3 days to obtain magnesium slag carbonation combined with gasification furnace slag building materials. The microstructure and properties of the sample are shown in Figure 2. Figure 6 and as shown in Table 4.

[0068] From the attached Figure 6 It can be seen that the CaCO3 formed by carbonation covers the uncarbonated hydration products and C2S particles on the surface of the sample, fills and connects the matrix and aggregates around the C2S, reduces the pores of the sample, and finally forms a dense microstructure, thereby improving the physical properties of the sample.

[0069] Table 5 Performance of magnesium slag carbonation combined with gasification furnace slag building materials corresponding to Example 4

[0070]

Claims

1. A method for preparing building materials by utilizing carbonation of magnesium slag combined with gasification slag, characterized in that: The following steps are included: Step 1: drying the magnesium slag raw material, crushing it, and then grinding it into fine powder using a ball mill to serve as the matrix fine powder; Step 2: drying the gasification slag raw material, crushing it, and screening it according to a certain particle size to use it as aggregate; Step 3, adding the aggregate, binder and matrix powder in sequence, mixing and placing in a sealed container or plastic bag for drying; Step 4: the scalded material is pressed into shape using a semi-dry method and then naturally aired; Step 5: Place the air-dried sample into a carbonation device for sample carbonation treatment, so as to obtain magnesium slag carbonation combined with gasification furnace slag to prepare building materials.

2. A method for preparing building materials by combining carbonation of magnesium slag with gasification slag according to claim 1, characterized in that: In the step 1, the magnesium slag is dried in an oven at 90° C.-120° C. for 24 h-48 h, and then ball-milled for 30-120 min. The particle size of the fine powder after ball milling is 0.05-100 μm.

3. A method for preparing building materials by combining carbonation of magnesium slag with gasification slag according to claim 1, characterized in that: In step 2, the gasification slag raw material must be dried in an oven at 90° C.-110° C. for 24 h-48 h.

4. The method for preparing building materials by combining carbonation of magnesium slag with gasification slag according to claim 1, wherein: In the step 2, the gasification slag crushed by the jaw crusher is screened into particle sizes of 1 to 3 mm and 0.5 to 3 mm.

5. The method for preparing building materials by carbonation of magnesium slag combined with gasification slag according to claim 1, characterized in that: In step 3, the weight ratio of aggregate to matrix powder is between (30-50): (50-70), and the binder accounts for 10-20% of the total weight of the aggregate and matrix powder.

6. The method for preparing building materials by utilizing carbonation of magnesium slag combined with gasification slag according to claim 1, characterized in that: In step 3, the binder dilution solution is first added to the aggregate and mixed for 3 to 5 minutes, and then the matrix powder is added and mixed for 3 to 5 minutes. The total mixing time in the roller mill is 10 to 20 minutes; In step 3, the sleeping time is 2 to 6 hours.

7. The method for preparing building materials by utilizing carbonation of magnesium slag combined with gasification slag according to claim 1, characterized in that: In step 4, bricks of a certain shape and size are pressed, and brick presses of different tonnages are used according to the size of the bricks; In step 4, the drying time is half a day to 1 day.

8. The method for preparing building materials by utilizing carbonation of magnesium slag combined with gasification slag according to claim 1, characterized in that: In step 5, the sample is carbonated in a controllable carbonation device, and the carbonation device is first heated to 40° C. to 70° C.; CO2 enters the equipment through the bubbling method, and the CO2 flow rate is controlled to ensure that the calcium carbonate generated by the carbonation reaction reacts completely. The temperature of the carbonation equipment is stable at 40℃~70℃, the volume fraction of CO2 in the CO2 gas is 50%~99%, the CO2 flow rate is 2L / min~6L / min, and the carbonation time is 1 day to 7 days.

9. A building material prepared by combining carbonation of magnesium slag with gasification slag, prepared according to the method according to any one of claims 1 to 8, characterized in that: Including CaCO3, CaCO3 covers the surface of uncarbonized hydration products and C2S particles, and fills and connects the matrix and aggregate around C2S. The presence of CaCO3 makes the three mixed together, thereby densifying the matrix; The CaCO3 is coated with C2S, periclase and ferrosilicon, and the contents of periclase and ferrosilicon are lower than that of C2S.

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