Mechanically activated coal gasification slag-based cementitious material and method for preparing the same

Abstract

The application discloses a kind of mechanically activated coal gasification slag-based cementitious materials and preparation method thereof, and relates to coal gasification furnace slag solid waste resource utilization.Preparation method includes the following steps: S10, obtaining pretreated coal gasification slag;S20, pretreated coal gasification slag is mixed with fused salt according to mass ratio (4-19) :1, and fused salt blend is obtained;S30, fused salt blend is mechanically ground, and activated coal gasification slag is obtained;S40, activated coal gasification slag, Portland cement and water are respectively taken and stirred and mixed, and precast slurry is obtained;S50, precast slurry is cast into shape and cured, and mechanically activated coal gasification slag-based cementitious material is obtained.The application precisely controls mechanical grinding parameters, and improves the cementitious performance of coal gasification slag in a targeted manner, meeting the diversified needs of cementitious materials in different application scenarios in actual engineering.

Description

A mechanically activated coal gasification slag-based cementitious material and its preparation method Technical Field

[0001] This invention belongs to the field of solid waste resource utilization technology of coal gasification furnace slag, specifically relating to a mechanically activated coal gasification slag-based cementitious material and its preparation method. Background Technology

[0002] Coal gasification slag is a major solid waste product of the coal chemical industry, with huge annual emissions. Its stockpiling not only occupies land resources but also easily causes environmental problems such as soil and water pollution. Coal gasification slag is mainly composed of oxides such as silicon, aluminum, and calcium, and has potential value as a cementitious material admixture. However, in its natural state, it has large particles, a dense crystal structure, and low reactivity. Directly adding it to cement will lead to problems such as insufficient cementitious material strength and poor fluidity, which seriously limits its resource utilization efficiency.

[0003] In existing technologies, the activation treatment of coal gasification slag often employs a single grinding method, such as simple ball milling. This method only increases fineness to activate the slag without considering the differentiated effects of grinding methods on the crystal structure and particle morphology of the slag. Furthermore, it fails to systematically study the matching relationship between activation products from different methods and key properties of cementitious materials, such as rheological and mechanical properties. In addition, existing methods lack precise control over grinding parameters, leading to unstable activation effects and difficulty in balancing slurry workability and material mechanical strength, thus failing to meet the diverse needs of engineering projects for cementitious materials.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a mechanically activated coal gasification slag-based cementitious material and its preparation method. The technical problem to be solved by this invention is achieved through the following technical solution:

[0006] This invention provides a method for preparing a mechanically activated coal gasification slag-based cementitious material, comprising the following steps:

[0007] S10. Remove metal impurities and particles larger than 5 mm from the coal gasification slag and dry it to a moisture content of no more than 2% to obtain pretreated coal gasification slag.

[0008] S20. The pretreated coal gasification slag and molten salt are mixed at a mass ratio of (4-19):1 to obtain a molten salt blend;

[0009] S30. The molten salt blend is mechanically ground to obtain activated coal gasification slag;

[0010] The relationships between the release of mechanochemical heat and the dissolution rate of active silicon, and between the release of mechanochemical heat and the dissolution rate of active aluminum during mechanical grinding are as follows:

[0011] ;

[0012] ;

[0013] in, The dissolution rate of active silicon; The parameter representing the maximum theoretical dissolution rate of active silicon is 50 ≤ ≤65; The kinetic coefficient for the dissolution of active silicon is 0.020 kg / kJ ≤ ≤0.025 kg / kJ; The linear enhancement factor for active silicon is 0.15 % / (kg / kJ) ≤ ≤0.20 % / (kg / kJ); The active aluminum dissolution rate, The parameter representing the maximum theoretical dissolution rate of active aluminum is 35≤ ≤50; The kinetic coefficient for the dissolution of active aluminum is 0.015 kg / kJ ≤ ≤0.020 kg / kJ; The linear enhancement factor for active aluminum is 0.10 % / (kg / kJ) ≤ ≤0.15% / (kg / kJ); This refers to the amount of heat released through mechanochemical processes. It is a natural constant;

[0014] The relationship between the amount of mechanochemical heat release and the time of mechanical grinding is as follows:

[0015] ;

[0016] in, Mechanochemical heat release The power of the equipment used for mechanical grinding; For the efficiency of converting mechanical energy into thermal energy, 0.6 ≤ ≤0.8; The time for mechanical grinding; The heat release coefficient of mechanical grinding is 0.030 min. -1 ≤ ≤0.070 min -1 ;

[0017] S40. Take M1 of the activated coal gasification slag, M2 of the silicate cement, and M3 of the water respectively and stir them to obtain a precast slurry.

[0018] Where M1 = (20%~40%) × (M1 + M2), (M1 + M2): M3 = 1: (0.4~0.6);

[0019] S50. The precast slurry is cast into shape and cured to obtain mechanically activated coal gasification slag-based cementitious material.

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

[0021] 1. This invention, by mixing molten salt with pretreated coal gasification slag in a specific ratio, clarifies the relationship between mechanical grinding parameters and cementitious active substances. Through precise control of mechanical grinding parameters (screening grinding equipment, optimizing process parameters, etc.), the performance of coal gasification slag-based cementitious materials can be improved in a targeted manner, resulting in cementitious materials with stable activation effects and predictable compressive strength. This meets the diversified needs of cementitious materials in different application scenarios in practical engineering, and is a key to breaking through existing technological bottlenecks and promoting the high-value utilization of coal gasification slag.

[0022] 2. The present invention systematically employs three differentiated mechanical grinding methods—ball milling, vibratory milling, and mechanical disc milling—to target and activate coal gasification slag. Through the systematic application and parameter optimization of these three differentiated mechanical grinding methods, the particle size, crystal structure, and particle morphology of the coal gasification slag are synergistically controlled, thereby achieving a directional improvement in the rheological properties of the slurry and the mechanical properties of the cementitious materials. This solves the technical problems of low activity, limited utilization methods, and difficulty in achieving a balance between performance and other aspects of coal gasification slag.

[0023] 3. The activated coal gasification slag product after ball milling in this invention, due to its equiaxed or spherical particle shape, can significantly improve the rheological properties of precast slurry, making it suitable for projects with high requirements for workability, such as pumped concrete and plastering mortar. The product from mechanical disc milling, due to more complete crystal structure destruction and higher amorphous material content, has the best mechanical properties, making it suitable for projects with high strength requirements, such as structural concrete and road base courses. The activated product from vibratory milling is suitable for general scenarios that balance workability and strength. Thus, the application range of coal gasification slag-based cementitious materials is broadened, solving the pain point of existing single activation methods that cannot balance workability and compressive strength, and providing more optional methods for the waste reuse of coal gasification slag.

[0024] 4. This invention realizes the high-value utilization of coal gasification slag, with the doping mass reaching up to 40% of the total mass of mixed solid cementitious materials. This significantly reduces cement usage, reduces solid waste storage pollution and carbon emissions from cement production, and can reduce production costs by 80-120 yuan per ton of cementitious materials, demonstrating good prospects for industrialization.

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1 is a flowchart of a method for preparing a mechanically activated coal gasification slag-based cementitious material according to an embodiment of the present invention;

[0027] Figure 2 is a SEM characterization image (scale bar 500 nm) of the activated coal gasification slag in Example 1 of the present invention;

[0028] Figure 3 is a SEM characterization image (scale bar 500 nm) of the activated coal gasification slag in Example 4 of the present invention.

[0029] Figure 4 is a SEM characterization image (scale bar 100 nm) of the activated coal gasification slag in Example 4 of the present invention.

[0030] Figure 5 is a SEM characterization image (scale bar 500 nm) of the activated coal gasification slag in Example 7 of the present invention.

[0031] Figure 6 is a schematic diagram comparing the XRD characterization diagrams of activated coal gasification slag in Examples 1, 4 and 7 of the present invention with the XRD characterization diagrams of pretreated coal gasification slag in the comparative example. Detailed Implementation

[0032] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a mechanically activated coal gasification slag-based cementitious material and its preparation method based on the present invention.

[0033] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0034] It should be noted that, in this document, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0035] The term "P·O 52.5 grade" in the instruction manual is the code specified in the Chinese national standard GB 175-2007 / XG3-2018; where P·O (Portland Ordinary) is ordinary Portland cement, and 52.5 represents the strength grade of the cement, which is the minimum compressive strength that cement mortar specimens prepared and cured according to standard methods can achieve at 28 days of age is not less than 52.5 MPa.

[0036] This invention provides a mechanically activated coal gasification slag-based cementitious material, comprising activated coal gasification slag and silicate cement, wherein the mass of the activated coal gasification slag is 20% to 40% of the sum of the masses of the activated coal gasification slag and silicate cement. In the cementitious material provided in this embodiment, the content of activated coal gasification slag can reach up to 40%, significantly improving the utilization of coal gasification slag. Furthermore, based on the high doping content, the mechanically activated coal gasification slag-based cementitious material exhibits a compressive strength greater than 50.0 MPa after 28 days. Simultaneously, based on different mechanical activation methods, the obtained cementitious material possesses precise adaptability to various application scenarios.

[0037] In some embodiments, the mass of activated coal gasification slag is 20%, 25%, 30%, 35%, or 40% of the sum of the masses of activated coal gasification slag and silicate cement.

[0038] Furthermore, activated coal gasification slag includes ball mill activated coal gasification slag, vibratory mill activated coal gasification slag, and mechanical disc mill activated coal gasification slag.

[0039] This invention also provides a method for preparing a mechanically activated coal gasification slag-based cementitious material, as shown in Figure 1, comprising the following steps:

[0040] S10. Remove metallic impurities and particles larger than 5 mm from the coal gasification slag, and dry it to a moisture content of no more than 2% to obtain pretreated coal gasification slag.

[0041] In one example, the coal gasification slag comprises 45%~55% SiO2, 15%~25% Al2O3, 5%~12% CaO, and 5%~13% Fe2O3 by mass, with a loss on ignition of less than or equal to 6%, and the total content of amorphous silicon oxide and amorphous aluminum oxide is not less than 60%.

[0042] S20. Mix the pretreated coal gasification slag and molten salt at a mass ratio of (4-19):1 to obtain a molten salt blend.

[0043] In one example, the molten salt is one or more of sodium nitrate, sodium chloride, sodium carbonate, or sodium sulfate. Thus, during the mechanical grinding activation process in step S30, the molten salt blend undergoes drastic lattice distortion due to the mechanical force, generating high-density dislocations, vacancies, and micro-strain. These changes help lower the melting point of the molten salt, ultimately bringing it to a molten state through the thermal energy generated by the mechanical force. The molten salt in this state can promote the depolymerization of the silicon-aluminum network in the coal gasification slag through ion exchange and surface corrosion, thereby increasing the precipitation of active silicon and active aluminum.

[0044] S30. Mechanically grind the molten salt blend to obtain activated coal gasification slag.

[0045] The relationships between the release of mechanochemical heat and the dissolution rate of active silicon, and between the release of mechanochemical heat and the dissolution rate of active aluminum during mechanical grinding are as follows:

[0046] ;

[0047] ;

[0048] in, The dissolution rate of active silicon; The parameter representing the maximum theoretical dissolution rate of active silicon is 50 ≤ ≤65; The kinetic coefficient for the dissolution of active silicon is 0.020 kg / kJ ≤ ≤0.025 kg / kJ; The linear enhancement factor for active silicon is 0.15 % / (kg / kJ) ≤ ≤0.20 % / (kg / kJ); The active aluminum dissolution rate, The parameter representing the maximum theoretical dissolution rate of active aluminum is 35≤ ≤50; The kinetic coefficient for the dissolution of active aluminum is 0.015 kg / kJ ≤ ≤0.020 kg / kJ; The linear enhancement factor for active aluminum is 0.10 % / (kg / kJ) ≤ ≤0.15% / (kg / kJ); This refers to the amount of heat released through mechanochemical processes. It is a natural constant;

[0049] The relationship between the amount of mechanochemical heat released and the time of mechanical grinding is as follows:

[0050] ;

[0051] in, Mechanochemical heat release The power of the equipment used for mechanical grinding; For the efficiency of converting mechanical energy into thermal energy, 0.6 ≤ ≤0.8; The time for mechanical grinding; The heat release coefficient of mechanical grinding is 0.030 min. -1 ≤ ≤0.070 min -1 .

[0052] The maximum theoretical dissolution rate parameter of activated silicon is higher than that of activated aluminum because the content of amorphous silicon oxide in coal gasification slag is usually much higher than that of amorphous aluminum oxide. Therefore, the network structure of amorphous silicon oxide is more prone to breakage under mechanical force, forming soluble SiO2. The dissolution kinetic coefficient reflects the initial response rate of the dissolution process to mechanical and thermal energy input. The bond energy of silicon-oxygen bonds (Si-O) is lower than that of aluminum-oxygen bonds (Al-O), making them more prone to breakage under mechanical impact and thermal energy. Thus, the dissolution kinetic coefficient of activated silicon is usually higher than that of activated aluminum, indicating that the dissolution rate of activated silicon increases faster under the same initial thermal energy input. The linear enhancement coefficient represents the linear increase in dissolution rate caused by continuous shear, temperature effects, etc., under high mechanical and thermal energy input. Mechanical grinding not only breaks particles but also introduces a large number of defects and unsaturated bonds on the newly formed surface. The network structure of silicon is more prone to plastic deformation and continuous deagglomeration under continuous stress, so its linear enhancement coefficient is more significant. The dissolution of active aluminum in the later stages is more limited by the local reorganization or encapsulation of mineral phases, and the linear enhancement effect is weaker.

[0053] In this step, through precise control of various parameters in the mechanical grinding process, on the one hand, the mechanical heat energy generated during mechanical grinding and the chemical activation effect of molten salt promote the dissolution of active silicon and active aluminum components in the coal gasification slag, forming activated coal gasification slag with cementing activity. On the other hand, mechanical grinding mechanically breaks down the coal gasification slag, achieving a synergistic effect of improving the fineness of the coal gasification slag and destroying its crystal structure. Thus, this invention can precisely control the mechanical grinding parameters based on the relationship between the release of mechanochemical heat and the dissolution rate of active silicon or active aluminum. This not only expands the reaction contact surface of the coal gasification slag but also promotes the formation of water-soluble amorphous substances. Compared with activation methods that simply improve fineness, the activation efficiency of reaction activity is increased by more than 30%, and the compressive strength of the cementitious material can reach up to 55.3 MPa, meeting the strength requirements of cementitious materials for engineering applications.

[0054] In one example, the melting point of the molten salt is lower than the operating temperature of the mechanical grinding process; during the mechanical grinding process, the molten salt is in a molten state and promotes the depolymerization of the silicon-aluminum network in the coal gasification slag through ion exchange and surface corrosion.

[0055] S40. Take M1 of activated coal gasification slag, M2 of silicate cement and M3 of water respectively and mix them to obtain a precast slurry; wherein, M1 = (20%~40%) × (M1+M2), (M1+M2):M3 = 1:(0.4~0.6).

[0056] In some examples, the silicate cement is ordinary silicate cement, and the minimum compressive strength of the silicate cement is not less than 52.5 MPa. That is to say, the silicate cement used in this example is P·O 52.5 grade or higher silicate cement.

[0057] In one example, the mixing in step S40 is carried out using a planetary ball mill; the planetary ball mill has a mixing speed of 100~150 r / min and a mixing time of 3~5 min.

[0058] S50. The precast slurry is poured into shape and cured to obtain a coal gasification slag-based cementitious material.

[0059] In one example, curing is carried out at a temperature of 18℃ to 22℃ and a relative humidity of ≥95% for 3 to 28 days.

[0060] The present invention provides a method for preparing mechanically activated coal gasification slag-based cementitious materials. By mixing molten salt with pretreated coal gasification slag in a specific ratio, the relationship between mechanical grinding parameters and cementitious active substances is clarified. Precise control of the mechanical grinding parameters allows for the acquisition of cementitious materials with stable activation effects and predictable compressive strength, meeting the diverse needs of cementitious materials in different application scenarios in practical engineering. Furthermore, the utilization rate and doping amount of coal gasification slag in the cementitious materials prepared by the method provided by this invention can reach 40% of the mixed solid cementitious materials (the sum of the masses of activated coal gasification slag and silicate cement), significantly reducing cement usage, reducing solid waste storage pollution and carbon emissions from cement production. Each ton of cementitious material can reduce production costs by 80-120 yuan, demonstrating promising industrialization prospects.

[0061] In the application of cementitious materials, not only the final compressive strength but also the workability during use, such as the fluidity of the precast slurry, must be considered, as this directly affects construction efficiency. Based on the precise control of the dissolution rate of active components in coal gasification slag, this invention further clarifies the correspondence between different mechanical grinding methods and the particle morphology, particle size, and crystal structure of the slag after mechanical grinding. This achieves directional optimization of the cementitious material, solving the problem of unstable activation effect caused by the difficulty in precise control of mechanical grinding in existing technologies. This results in a cementitious material with high adaptability to different application scenarios.

[0062] In one embodiment of the present invention, in step S30, the mechanical grinding is performed using a ball milling process. Under the conditions of a ball-to-material ratio of (8~12):1, a ball milling speed of 200 r / min~300 r / min, and a ball milling time of 0.5 h~5 h, ball mill-activated coal gasification slag is obtained; the specific surface area of ​​the ball mill-activated coal gasification slag is 350 m². 2 / kg ~500 m 2 / kg, with a crystallinity of 15%~30%. Using ball milling technology, energy transfer mainly occurs through the impact and collision of the milling media (e.g., steel balls); some energy is consumed in collisions between milling media and between milling media and liners, as well as in equipment vibration, and is not fully transferred to the material. While the instantaneous energy density of the impact is high, the small contact area results in relatively large energy loss. Therefore, the mechanical energy to heat conversion efficiency in the formula is... The value range is 0.60≤ ≤0.70. Meanwhile, the energy input in ball milling is periodic (drop-impact), resulting in high instantaneous energy input intensity but low average density; ball mills are typically rotary drum structures, large in volume, and have a high total heat capacity of the milling media and materials; a large amount of energy is consumed in raising the temperature of the entire system, therefore the mechanical grinding heat release coefficient is low. The value range is 0.030 min. -1 ≤ ≤0.042 min -1 .

[0063] The ball-milled activated coal gasification slag particles obtained by ball milling are equiaxed or spherical, which can significantly improve the rheological properties of precast slurries prepared using ball-milled activated coal gasification slag (see Figure 2). This makes the ball-milled activated coal gasification slag-based cementitious materials more suitable for projects with high construction fluidity requirements, such as pumped concrete and plastering mortar.

[0064] In one example, the grinding media used in the ball milling process can be steel balls, agate balls, or corundum balls. The particle size of the grinding media is 10–35 mm.

[0065] In another embodiment of the present invention, in step S30, the mechanical grinding adopts a vibration milling process, and under the conditions of a vibration frequency of 15 Hz to 25 Hz and a vibration milling time of 0.5 h to 5 h, vibration mill activated coal gasification slag is obtained; the specific surface area of ​​the vibration mill activated coal gasification slag is 400 m². 2 / kg~550 m 2 / kg, crystallinity 12%~25%. Utilizing a vibratory milling process, the mechanical energy to heat energy conversion efficiency is high. The value range is 0.65≤ ≤0.75, the grinding media generate intense relative motion and friction under high-frequency vibration, with line contact and rolling contact being the main modes of interaction between the grinding media and the coal gasification slag. Continuous, high-frequency micro-impact and friction ensure a more sustained and uniform conversion of energy into heat. Compared to ball milling, its energy transfer is more direct, with less macroscopic kinetic energy wasted; therefore, its mechanical energy to heat conversion efficiency is generally higher than that of ball milling. The mechanical grinding heat release coefficient of the vibratory mill process. The value range is 0.050 min. -1 ≤ ≤0.070 min -1 The high-frequency vibration of the vibratory mill causes countless collisions and frictions between the grinding media and the gasification slag, and between the gasification slag and the liner, within a unit of time, converting mechanical energy into heat energy almost without interruption. Furthermore, the relatively small size of the equipment, the fluidized state of the gasification slag within the vibratory mill, the large contact area with the grinding media, and the high heat transfer efficiency allow heat to accumulate rapidly throughout the entire grinding system, resulting in a rapid temperature rise.

[0066] Referring to Figure 3, the average particle size of the vibratory mill-activated coal gasification slag is slightly smaller than that of the ball mill-activated coal gasification slag, but the morphology of the vibratory mill-activated coal gasification slag is not as rounded. Figure 4 is a partial enlarged view of Figure 3, showing that the surface of the vibratory mill-activated coal gasification slag has nanoscale cracks, which can further improve the dissolution of active silicon and active aluminum components, thereby increasing the compressive strength of the prepared vibratory mill-activated coal gasification slag-based cementitious material. Thus, the vibratory mill-activated coal gasification slag obtained by the vibratory mill process can be used to prepare cementitious materials that balance fluidity and strength, broadening the application range of coal gasification slag-based cementitious materials.

[0067] For example, vibratory mill-activated coal gasification slag-based cementitious materials can be used in autoclaved aerated concrete (AAC) blocks or concrete / mortar admixtures. When used in AAC blocks, the fluidity of the precast slurry prepared with vibratory mill-activated coal gasification slag ensures uniform foaming and avoids uneven pore size; and the hardened strength meets the requirements of non-load-bearing walls, balancing thermal insulation and structural stability. When used in concrete / mortar admixtures, the fluidity of the precast slurry prepared with vibratory mill-activated coal gasification slag ensures rapid mixing with cement and aggregates, preventing segregation during pouring; the strength can improve the compressive strength of concrete, making it suitable for structural engineering such as building beams, columns, floor slabs, and road construction.

[0068] In another embodiment of the present invention, in step S30, the mechanical grinding is carried out using a mechanical disc milling process. Under the conditions of a mechanical disc milling pressure of 0.3 MPa to 0.6 MPa, a mechanical disc milling speed of 500 r / min to 800 r / min, and a mechanical disc milling time of 30 s to 600 s, mechanically disc milled activated coal gasification slag is obtained; the specific surface area of ​​the mechanically disc milled activated coal gasification slag is 450 to 600 m². 2 / kg, crystallinity 8%~20%. Utilizing a mechanical disc milling process, strong shearing and compressive forces are applied to the material layer through surface contact between the grinding disc and rollers. This action is very direct; the vast majority of the mechanical work is used to overcome internal friction and plastic deformation of the material, directly converting into heat. Therefore, the conversion efficiency between mechanical energy and thermal energy is high. The value range is 0.7≤ ≤0.8. Mechanical disc milling provides continuous and high-intensity energy input through surface contact shearing and compression. Compared to vibratory mills, it has a thicker material bed, a typically larger equipment structure, and a larger heat capacity, which slows down the temperature rise rate to some extent. Therefore, the heat release coefficient of mechanical grinding is... The value range is 0.045 min. -1 ≤ ≤0.065 min -1 It is slightly lower than the vibratory mill process.

[0069] The mechanical disc milling process produces mechanically milled activated coal gasification slag with more complete crystal structure destruction, higher amorphous material content, and higher active silicon and active aluminum dissolution rates, resulting in superior mechanical properties of the cementitious material based on mechanically milled activated coal gasification slag. For example, the mechanically milled activated coal gasification slag-based cementitious material prepared from this process is more suitable for projects with high strength requirements, such as structural concrete and road base courses.

[0070] The performance of the mechanically activated coal gasification slag-based cementitious material provided by the present invention will be further explained below with reference to specific embodiments.

[0071] Example 1

[0072] Step 1: Raw material pretreatment: Select coal gasification slag produced by a coal chemical enterprise; according to mass content, the chemical composition of the coal gasification slag is SiO2 52.70%, Al2O3 16.56%, CaO 10.78%, Fe2O3 9.27%, and loss on ignition 2.37%. Remove metallic impurities and large particles with a particle size greater than 5 mm from the coal gasification slag, and dry it in an oven at 105 ℃ for 4 h to reduce the moisture content of the coal gasification slag to less than 1.5%, thus obtaining pretreated coal gasification slag.

[0073] Step 2, Molten Salt Blending: The pretreated coal gasification slag and molten salt are mixed at a mass ratio of 9:1 to obtain a molten salt blend. The molten salt is a mixture of sodium nitrate and sodium sulfate, and the amount of molten salt is 10% of the total mass of the molten salt blend.

[0074] Step 3, Mechanical Grinding and Activation: Ball milling was used with steel balls as the grinding medium at a ball-to-material ratio of 10:1, a milling speed of 250 r / min, and a milling time of 2 h to obtain ball-milled activated coal gasification slag. The ball-milled activated coal gasification slag obtained in Example 1 is defined as activated coal gasification slag 1. Referring to Figure 2, which shows the scanning electron microscope (SEM) characterization of the activated coal gasification slag 1 obtained after ball milling in this example, it can be seen that the particles are mostly equiaxed or spherical. This morphology gives the pre-formed slurry of the cementitious material prepared from the ball-milled activated coal gasification slag high fluidity and high flowability (the flowability of pre-formed slurry 1 in this example is 270 mm).

[0075] Step 4: Preparation of cementitious material: The ball-milled activated coal gasification slag is mixed with P·O 52.5 grade cement (containing 95% cement clinker and 5% gypsum) to form a mixed solid cementitious material. The mass of the ball-milled activated coal gasification slag is 30% of the mass of the mixed solid cementitious material. Water is added at a mass ratio of 0.5 to the mixed solid cementitious material. The mixture is stirred using a planetary ball mill at 120 r / min for 4 min to obtain a pre-formed slurry. The pre-formed slurry obtained in Example 1 is defined as pre-formed slurry 1.

[0076] Step 5, Standard Curing: The precast slurry was poured into 40 mm × 40 mm × 160 mm specimens and cured in a standard curing chamber at 20℃ and 98% relative humidity for 28 days to obtain the ball-milled activated coal gasification slag-based cementitious material. The ball-milled activated coal gasification slag-based cementitious material prepared in Example 1 is defined as activated coal gasification slag-based cementitious material 1.

[0077] Performance testing:

[0078] (1) The dissolution rate of active silicon and active aluminum in activated coal gasification slag

[0079] The active silicon (amorphous silica) in activated coal gasification slag was determined using the potassium fluorosilicate titration method. The specific principle is as follows: H₂SiO₃ reacts with excess F... - and K + In a strongly acidic solution, it can react with F. - The reaction forms fluorosilicate ions (SiF6). 2- ), and further with K + The reaction produces potassium fluorosilicate (K2SiF6) precipitate, which hydrolyzes in hot water and reacts to produce an equivalent amount of HF. Therefore, the content of active SiO2 in the sample can be determined by titration with NaOH solution.

[0080] The active aluminum (amorphous aluminum oxide) in activated coal gasification slag was determined by EDTA complexometric titration. The specific principle is as follows: Al 3+ It can form a complex with EDTA. An excess of EDTA standard solution is added to the solution beforehand to adjust the pH to 4, in order to accelerate the formation of Al... 3+ The rate of complexation reaction with EDTA requires heating the solution to boiling to ensure complete complexation, using xylenol orange as an indicator. Then, the remaining EDTA in the solution is back-titrated with standard zinc sulfate solution. The reaction rate is determined based on the actual reaction with Al. 3+ The Al2O3 content in the sample is calculated by the amount of complexed EDTA.

[0081] The activated coal gasification slag 1 obtained in step 3 of Example 1 was used to measure the active silicon dissolution rate and the active aluminum dissolution rate using the above method. Three sets of measurements were repeated, and the average value was taken. The active silicon dissolution rate of the activated coal gasification slag 1 was 45%, and the active aluminum dissolution rate was 34%.

[0082] (2) Specific surface area and crystallinity of activated coal gasification slag

[0083] The specific surface area of ​​the activated coal gasification slag 1 obtained in Example 1 was tested using the Blaine method. Specifically, it was based on the national standard GB / T 8074-2008, "Method for Determination of Specific Surface Area of ​​Cement - Blaine Method". The specific surface area of ​​the activated coal gasification slag 1 in Example 1 was 410 m². 2 / kg.

[0084] Referring to Figure 6, the crystallinity of the activated coal gasification slag 1 obtained in Example 1 was measured by X-ray diffraction (XRD). The crystallinity of the activated coal gasification slag 1 in Example 1 was 23%. In Figure 6, Raw CGS represents the raw coal gasification slag (unmilled), and QM represents the activated coal gasification slag obtained by ball milling in Example 1.

[0085] (3) Flowability of precast slurry

[0086] The flowability of the precast slurry 1 obtained in Example 1 was tested using the standard test method for cement paste flowability. Specifically, the well-mixed sample was slowly poured into a truncated conical mold, and the mold opening was smoothed with a scraper. The mold was then quickly lifted vertically while timing was initiated. After the slurry stopped spreading on a smooth glass plate, its spreading diameter was measured vertically with a ruler. At least six measurements were taken, and the arithmetic mean was used as the flowability result. The entire process must be completed within 6 minutes to ensure consistent test conditions and reliable data.

[0087] In Example 1, the flowability of pre-prepared slurry 1 is 270 mm, indicating good fluidity.

[0088] (4) Compressive strength of coal gasification slag-based cementitious materials

[0089] In Example 1, the compressive strength of activated coal gasification slag-based cementitious material 1 after curing for 28 days was 51.2 MPa, which meets the requirements for cementitious materials used in structural concrete.

[0090] Example 2

[0091] The difference between this embodiment and Embodiment 1 is that in step 4, the blending mass of the ball-milled activated coal gasification slag is 20% of the mass of the mixed solid cementitious material, and the obtained pre-formed slurry is defined as pre-formed slurry 2. The ball-milled activated coal gasification slag-based cementitious material obtained in step 5 is defined as activated coal gasification slag-based cementitious material 2.

[0092] The remaining operations and parameters are the same as in Example 1.

[0093] Using the same testing method as in Example 1, the fluidity of the pre-prepared slurry 2 was measured to be 275 mm, and the compressive strength of the activated coal gasification slag-based cementitious material 2 was measured to be 53.1 MPa.

[0094] Example 3

[0095] The difference between this embodiment and Embodiment 1 is that in step 4, the blending mass of the ball-milled activated coal gasification slag is 40% of the mass of the mixed solid cementitious material, and the obtained pre-formed slurry is defined as pre-formed slurry 3. The ball-milled activated coal gasification slag-based cementitious material obtained in step 5 is defined as activated coal gasification slag-based cementitious material 3.

[0096] The remaining operations and parameters are the same as in Example 1.

[0097] Using the same testing method as in Example 1, the fluidity of the pre-prepared slurry 3 was measured to be 260 mm, and the compressive strength of the activated coal gasification slag-based cementitious material 3 was measured to be 48.5 MPa.

[0098] Example 4

[0099] Step 1, the operation and parameters are the same as in Example 1.

[0100] Step 2, the operation and parameters are the same as in Example 1.

[0101] Step 3, Mechanical Grinding Activation: A vibratory mill process was used, with a vibration frequency of 20 Hz and a grinding time of 2 h, to obtain vibratory mill activated coal gasification slag. The vibratory mill activated coal gasification slag obtained in Example 4 is defined as activated coal gasification slag 2. Referring to Figures 3 and 4, which are scanning electron microscope (SEM) characterization images of the activated coal gasification slag 2 obtained after vibratory milling in this example, it can be seen from the figures that the particles of activated coal gasification slag 2 are mostly irregularly shaped lumps. Further magnified images show that the surface of the activated coal gasification slag 2 particles has nanoscale grooves formed by the vibratory milling, which further improves the dissolution rate of active silicon and active aluminum in the activated coal gasification slag 2.

[0102] Step 4, Preparation of Cementitious Material: The activated coal gasification slag from the vibratory mill is mixed with P·O 52.5 grade cement to form a mixed solid cementitious material. The mass of the activated coal gasification slag from the vibratory mill is 30% of the mass of the mixed solid cementitious material. Water is added at a mass ratio of 0.5 to the mixed solid cementitious material. The mixture is stirred using a planetary ball mill at 120 r / min for 4 min to obtain a pre-formed slurry. The pre-formed slurry obtained in Example 4 is defined as pre-formed slurry 4.

[0103] Step 5, the operation, and parameters are the same as in Example 1. The vibratory mill-activated coal gasification slag-based cementitious material prepared in Example 4 is defined as activated coal gasification slag-based cementitious material 4.

[0104] Performance testing:

[0105] Using the same detection method as in Example 1, the active silicon dissolution rate of activated coal gasification slag 2 was found to be 50%, and the active aluminum dissolution rate was 38%; the specific surface area of ​​activated coal gasification slag 2 was 460 m². 2 / kg. As shown in Figure 6, the crystallinity was measured by X-ray diffraction (XRD), and the crystallinity of activated coal gasification slag 2 was 20%. In Figure 6, ZD represents the activated coal gasification slag obtained by the vibratory mill in Example 4.

[0106] The fluidity of the precast slurry 4 is 260 mm, and the compressive strength of the activated coal gasification slag-based cementitious material 4 is 53.7 MPa.

[0107] Example 5

[0108] The difference between this embodiment and embodiment 4 is that in step 4, the blending mass of the vibratory mill activated coal gasification slag is 20% of the mass of the mixed solid cementitious material, and the obtained pre-formed slurry is defined as pre-formed slurry 5. The vibratory mill activated coal gasification slag-based cementitious material obtained in step 5 is defined as activated coal gasification slag-based cementitious material 5.

[0109] The remaining operations and parameters are the same as in Example 4.

[0110] Using the same testing method as in Example 1, the fluidity of the pre-prepared slurry 5 was measured to be 273 mm, and the compressive strength of the activated coal gasification slag-based cementitious material 5 was measured to be 54.6 MPa.

[0111] Example 6

[0112] The difference between this embodiment and Embodiment 4 is that in step 4, the blending mass of the vibratory mill activated coal gasification slag is 40% of the mass of the mixed solid cementitious material, and the obtained pre-formed slurry is defined as pre-formed slurry 6. The vibratory mill activated coal gasification slag-based cementitious material obtained in step 5 is defined as activated coal gasification slag-based cementitious material 6.

[0113] The remaining operations and parameters are the same as in Example 4.

[0114] Using the same testing method as in Example 1, the fluidity of the pre-prepared slurry 6 was measured to be 250 mm, and the compressive strength of the activated coal gasification slag-based cementitious material 6 was measured to be 49.3 MPa.

[0115] Example 7

[0116] Step 1, the operation and parameters are the same as in Example 1.

[0117] Step 2, the operation and parameters are the same as in Example 1.

[0118] Step 3, Mechanical Grinding and Activation: A mechanical disc milling process was adopted, with the grinding disc pressure set at 0.5 MPa, the rotation speed at 650 r / min, and the grinding time at 120 s, to obtain mechanically disc-milled activated coal gasification slag. The mechanically disc-milled activated coal gasification slag obtained in Example 7 is defined as activated coal gasification slag 3. Referring to Figure 5, it is a scanning electron microscope (SEM) characterization image of the activated coal gasification slag 3 obtained after mechanical disc milling in this example. It can be seen from the figure that the activated coal gasification slag 3 is mostly in the form of thin flakes, indicating that mechanical disc milling has a more thorough destruction of the coal gasification slag structure. However, the flake-like particles restrict the flowability of the activated coal gasification slag 3, resulting in a flowability of 250 mm for the pre-prepared slurry, which is less than the flowability of the pre-prepared slurry prepared by activated coal gasification slag 1 and activated coal gasification slag 2.

[0119] Step 4, Preparation of Cementitious Material: Mechanically activated coal gasification slag from a disc mill is mixed with P·O 52.5 grade cement to form a mixed solid cementitious material. The mass of the mechanically activated coal gasification slag is 30% of the mass of the mixed solid cementitious material. Water is added at a mass ratio of 0.5 to the mixed solid cementitious material. The mixture is stirred using a planetary ball mill at 120 r / min for 4 min to obtain a pre-formed slurry. The pre-formed slurry obtained in Example 7 is defined as pre-formed slurry 7.

[0120] Step 5, the operation, and parameters are the same as in Example 1. The mechanically milled activated coal gasification slag-based cementitious material prepared in Example 7 is defined as activated coal gasification slag-based cementitious material 7.

[0121] Performance testing:

[0122] Using the same detection method as in Example 1, the active silicon dissolution rate of the activated coal gasification slag 3 was found to be 56%, and the active aluminum dissolution rate was 45%. The specific surface area of ​​the activated coal gasification slag 3 was 520 m². 2 / kg. As shown in Figure 6, the crystallinity was measured by X-ray diffraction (XRD), and the crystallinity of activated coal gasification slag 3 was 14%. In Figure 6, PM represents the activated coal gasification slag obtained by mechanical disc milling in Example 7.

[0123] The fluidity of the precast slurry 7 is 250 mm, and the compressive strength of the activated coal gasification slag-based cementitious material 7 is 55.3 MPa.

[0124] Example 8

[0125] The difference between this embodiment and Embodiment 7 is that in step 4, the blending mass of the mechanically milled activated coal gasification slag is 20% of the mass of the mixed solid cementitious material, and the obtained pre-formed slurry is defined as pre-formed slurry 8. The mechanically milled activated coal gasification slag-based cementitious material obtained in step 5 is defined as activated coal gasification slag-based cementitious material 8.

[0126] The remaining operations and parameters are the same as in Example 7.

[0127] Using the same testing method as in Example 1, the fluidity of the pre-prepared slurry 8 was measured to be 260 mm, and the compressive strength of the activated coal gasification slag-based cementitious material 8 was measured to be 57.4 MPa.

[0128] Example 9

[0129] The difference between this embodiment and Embodiment 7 is that in step 4, the blending mass of the mechanically milled activated coal gasification slag is 40% of the mass of the mixed solid cementitious material, and the obtained pre-formed slurry is defined as pre-formed slurry 9. The mechanically milled activated coal gasification slag-based cementitious material obtained in step 5 is defined as activated coal gasification slag-based cementitious material 9.

[0130] The remaining operations and parameters are the same as in Example 7.

[0131] Using the same testing method as in Example 1, the fluidity of the pre-prepared slurry 9 was measured to be 235 mm, and the compressive strength of the activated coal gasification slag-based cementitious material 9 was measured to be 53.5 MPa.

[0132] Comparative Example

[0133] Step 1: Raw material pretreatment: Coal gasification slag produced by a coal chemical enterprise was selected. Based on mass content, the chemical composition of this slag was SiO2 52.70%, Al2O3 16.56%, CaO 10.78%, Fe2O3 9.27%, with a loss on ignition of 2.37%. Metallic impurities and large particles larger than 5 mm were removed from the slag. The slag was then dried in an oven at 105 ℃ for 4 h to reduce the moisture content to less than 1.5%, thus obtaining pretreated coal gasification slag.

[0134] Step 2, Preparation of cementitious material: The pretreated coal gasification slag is mixed with P·O 52.5 grade cement to form a mixed solid cementitious material. The mixing mass of the pretreated coal gasification slag is 30% of the mass of the mixed solid cementitious material. Water is added at a mass ratio of 0.5 to the mixed solid cementitious material. The mixture is stirred using a planetary ball mill at a speed of 120 r / min for 4 min to obtain pre-mixed slurry 11.

[0135] Step 3, Standard Curing: The precast slurry is poured into 40 mm × 40 mm × 160 mm specimens and cured in a standard curing chamber at 20℃ and 98% relative humidity for 28 days to obtain coal gasification slag-based cementitious material.

[0136] Using the detection method described in Example 1, the active silicon dissolution rate of the pretreated coal gasification slag in step 1 of the comparative example was found to be 5.6%, and the active aluminum dissolution rate was 3.8%; the specific surface area of ​​the pretreated coal gasification slag was 140 m². 2 / kg, with a crystallinity of 55%. In this comparative example, the fluidity of pre-prepared slurry 11 is 160 mm, and the compressive strength of the coal gasification slag-based cementitious material after curing for 28 days is 32.5 MPa.

[0137] Results analysis:

[0138] Compared with the comparative examples, the activated coal gasification slag obtained after mechanical grinding in Examples 1, 4, and 7 showed an increase of nearly 10 times in active silica dissolution rate and nearly 12 times in active aluminum dissolution rate. This improved the reactivity of the activated coal gasification slag with calcium hydroxide in cement hydration products, generating cementitious products (such as calcium silicate hydrate (CSH) gel and calcium aluminate hydrate (CAH)), thus increasing the compressive strength of the final mechanically activated coal gasification slag-based cementitious material. Simultaneously, the activated coal gasification slag obtained after mechanical grinding in Examples 1, 4, and 7 showed a significant increase in specific surface area and a decrease in crystallinity. Furthermore, the flowability of the pre-formulated slurry prepared using the mechanically activated coal gasification slag was improved, indicating that the particle size of the mechanically activated coal gasification slag was reduced, the crystalline structure was damaged, and the flowability was improved. In other words, compared with the comparative examples, the rheological properties of the pre-formulated slurry and the mechanical properties of the cementitious material obtained from the mechanically ground coal gasification slag provided by this invention were significantly improved.

[0139] Combining Examples 1, 4, and 7, these three examples compare the performance of coal gasification slag activated using different mechanical grinding methods, all with a doping mass of 30% mixed solid cementitious material. The results show that the activated coal gasification slag 1 obtained by ball milling in Example 1 has a smaller specific surface area, and the particle structure of the ball-milled activated coal gasification slag is mostly equiaxed or spherical (see Figure 2). This results in good flowability of the cementitious material prepared from the ball-milled activated coal gasification slag 1, making it suitable for projects with high construction flowability requirements. In Example 7, the activated coal gasification slag 3 obtained by mechanical disc milling has a higher amount of active silicon and active aluminum precipitation, resulting in high compressive strength of the mechanically disc-milled activated coal gasification slag-based cementitious material, making it particularly suitable for projects with high strength requirements, such as structural concrete and road base layers. The activated coal gasification slag 2 obtained by vibratory milling in Example 4 can simultaneously achieve both flowability and strength, making it versatile in projects requiring a comprehensive consideration of workability and strength.

[0140] In the results of Examples 1, 2, and 3, when the blending mass of ball-milled activated coal gasification slag was 20%, the flowability of precast slurry 2 reached 275 mm, and the compressive strength of the prepared activated coal gasification slag-based cementitious material 2 reached 53.1 MPa. Further increasing the blending mass of ball-milled activated coal gasification slag to 40%, the compressive strength of the prepared activated coal gasification slag-based cementitious material 3 still met the requirements for use in the civil engineering field. This indicates that the activated coal gasification slag prepared by ball milling not only improves the compressive strength of the cementitious material but also significantly improves the flowability of the precast slurry (at a blending mass of 40%, the flowability of precast slurry 3 still reached 260 mm).

[0141] In the results of Examples 4, 5, and 6, when the blending mass of the vibratory mill activated coal gasification slag was 20%, the flowability of the pre-prepared slurry 5 was 273 mm, and the compressive strength of the prepared activated coal gasification slag-based cementitious material 5 reached as high as 53.6 MPa. Even when the blending mass of the vibratory mill activated coal gasification slag was increased to 40%, the flowability of the pre-prepared slurry 6 was 250 mm, and the compressive strength of the prepared activated coal gasification slag-based cementitious material 6 was still as high as 49.3 MPa. This indicates that the cementitious material obtained by the vibratory mill process can simultaneously achieve both flowability and compressive strength, and has higher versatility in various scenarios.

[0142] In the results of Examples 7, 8, and 9, when the blending mass of mechanically milled activated coal gasification slag was 20%, the flowability of the pre-prepared slurry 5 was 260 mm, and the compressive strength of the prepared activated coal gasification slag-based cementitious material 5 reached 57.4 MPa, indicating that the cementitious material obtained by the mechanical milling process has good flowability and high compressive strength. However, when the blending mass of mechanically milled activated coal gasification slag was increased to 40%, the higher active silica and active aluminum dissolution rates of the mechanical milling activation process showed significant advantages, and the flowability of the pre-prepared slurry 9 decreased significantly (235 mm). Even with a blending mass of 40% mechanically milled activated coal gasification slag, the prepared activated coal gasification slag-based cementitious material 9 still possessed a compressive strength of 53.5 MPa.

[0143] This invention utilizes the mechanical heat energy generated during mechanical grinding and the chemical activation effect of molten salt to promote the dissolution of active silicon and active aluminum components in coal gasification slag, forming activated coal gasification slag with cementing activity. Through precise control of mechanical grinding parameters, a synergistic effect of fineness improvement and crystal structure destruction is achieved, expanding the reaction contact surface of the coal gasification slag and promoting the formation of water-soluble amorphous substances. Compared to activation methods that simply improve fineness, the reactivity activation efficiency is increased by more than 30%, and the compressive strength of the cementitious material can reach up to 55.3 MPa, meeting the strength requirements for cementitious materials used in engineering.

[0144] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0145] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a mechanically activated coal gasification slag-based cementitious material, characterized in that, Includes the following steps: S10. Remove metallic impurities and particles larger than 5 mm from the coal gasification slag, and dry it to a moisture content of no more than 2% to obtain pretreated coal gasification slag; S20. Mix the pretreated coal gasification slag with molten salt at a mass ratio of (4-19):1 to obtain a molten salt blend; wherein the molten salt is one or more of sodium nitrate, sodium chloride, sodium carbonate, or sodium sulfate; S30. Mechanically grind the molten salt blend to obtain activated coal gasification slag; the relationship between the mechanical chemical heat release and the active silicon dissolution rate, and the relationship between the mechanical chemical heat release and the active aluminum dissolution rate during the mechanical grinding process are as follows: ； ;in, The dissolution rate of active silicon; The parameter representing the maximum theoretical dissolution rate of active silicon is 50 ≤ ≤65； The kinetic coefficient for the dissolution of active silicon is 0.020 kg / kJ ≤ ≤0.025 kg / kJ; The linear enhancement factor for active silicon is 0.15 % / (kg / kJ) ≤ ≤0.20 % / (kg / kJ); The active aluminum dissolution rate, The parameter representing the maximum theoretical dissolution rate of active aluminum is 35≤ ≤50； The kinetic coefficient for the dissolution of active aluminum is 0.015 kg / kJ ≤ ≤0.020kg / kJ; The linear enhancement factor for active aluminum is 0.10 % / (kg / kJ) ≤ ≤0.15 % / (kg / kJ); This refers to the amount of heat released through mechanochemical processes. It is a natural constant; the relationship between the amount of mechanochemical heat released and the time of mechanical grinding is as follows: ;in, Mechanochemical heat release The power of the equipment used for mechanical grinding; For the efficiency of converting mechanical energy into thermal energy, 0.6 ≤ ≤0.8； The time for mechanical grinding; The heat release coefficient of mechanical grinding is 0.030 min. -1 ≤ ≤0.070 min -1 S40. Take M1 of the activated coal gasification slag, M2 of silicate cement, and M3 of water respectively and stir them to obtain a precast slurry; wherein, M1 = (20%~40%) × (M1+M2), (M1+M2):M3 = 1:(0.4~0.6); S50. Cast the precast slurry into shape and cure it to obtain a mechanically activated coal gasification slag-based cementitious material.

2. The preparation method of the mechanically activated coal gasification slag-based cementitious material according to claim 1, characterized in that, In step S10, the coal gasification slag includes SiO2 with a mass content of 45%~55%, Al2O3 with a mass content of 15%~25%, CaO with a mass content of 5%~12%, and Fe2O3 with a mass content of 5%~13%, with a loss on ignition of less than or equal to 6%, and the total content of amorphous silicon oxide and amorphous aluminum oxide is not less than 60%.

3. The method for preparing mechanically activated coal gasification slag-based cementitious material according to claim 1 or 2, characterized in that, In step S30, the mechanical grinding is performed using ball milling. Under the conditions of a ball-to-material ratio of (8~12):1, a ball milling speed of 200 r / min~300 r / min, and a ball milling time of 0.5 h~5 h, ball mill activated coal gasification slag is obtained; the specific surface area of ​​the ball mill activated coal gasification slag is 350 m². 2 / kg ~500 m 2 / kg, with a crystallinity of 15%~30%; ball milling process is used, and the mechanical energy to heat energy conversion efficiency is... The value range is 0.60≤ The mechanical grinding heat release coefficient is ≤0.

70. The value range is 0.030 min. -1 ≤ ≤0.042 min -1 。 4. The method for preparing mechanically activated coal gasification slag-based cementitious material according to claim 1 or 2, characterized in that, In step S30, the mechanical grinding is carried out using a vibratory mill process, with a vibration frequency of 15 Hz to 25 Hz and a vibration milling time of 0.5 h to 5 h, to obtain vibratory mill activated coal gasification slag; the specific surface area of ​​the vibratory mill activated coal gasification slag is 400 m². 2 / kg ~550 m 2 / kg, crystallinity 12%~25%; using vibratory milling process, the mechanical energy to heat energy conversion efficiency is... The value range is 0.65≤ The mechanical grinding heat release coefficient is ≤0.

75. The value range is 0.050 min. -1 ≤ ≤0.070 min -1 。 5. The method for preparing mechanically activated coal gasification slag-based cementitious material according to claim 1 or 2, characterized in that, In step S30, the mechanical grinding is carried out using a mechanical disc milling process. Under the conditions of a mechanical disc milling pressure of 0.3 MPa to 0.6 MPa, a mechanical disc milling speed of 500 r / min to 800 r / min, and a mechanical disc milling time of 30 s to 600 s, mechanically disc milled activated coal gasification slag is obtained. The specific surface area of ​​the mechanically disc milled activated coal gasification slag is 450 to 600 m² / kg, and the crystallinity is 8% to 20%. Using the mechanical disc milling process, the mechanical energy to heat energy conversion efficiency is... The value range is 0.7≤ The mechanical grinding heat release coefficient is ≤0.

8. The value range is 0.045 min. -1 ≤ ≤0.065 min -1 。 6. The method for preparing mechanically activated coal gasification slag-based cementitious material according to claim 1, characterized in that, In step S40, the silicate cement is ordinary silicate cement, and the minimum compressive strength of the silicate cement is not less than 52.5 MPa; the mixing is carried out using a planetary ball mill; the stirring speed of the planetary ball mill is 100 r / min ~ 150 r / min, and the stirring time is 3 min ~ 5 min.

7. The method for preparing mechanically activated coal gasification slag-based cementitious material according to claim 1, characterized in that, In step S50, the curing is carried out for 3 to 28 days at a temperature of 18℃ to 22℃ and a relative humidity of 95% or higher.

8. A mechanically activated coal gasification slag-based cementitious material, characterized in that, The mechanically activated coal gasification slag-based cementitious material is obtained by any one of the preparation methods provided in claims 1-7; the material comprises activated coal gasification slag and silicate cement, wherein the mass of the activated coal gasification slag is 20% to 40% of the sum of the masses of the activated coal gasification slag and the silicate cement.

9. The mechanically activated coal gasification slag-based cementitious material according to claim 8, characterized in that, The activated coal gasification slag includes ball mill activated coal gasification slag, vibratory mill activated coal gasification slag, or mechanical disc mill activated coal gasification slag.

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