Simulation aided design method for iron tailings based geopolymer material

Abstract

The present application belongs to the technical field of solid waste resource utilization, and particularly relates to a simulation aided design method of iron tailing based geopolymer material. The method firstly defines the basic assumptions required for simulation and selects a suitable force field; then determines the basic chemical structure unit of the system, and constructs the corresponding geopolymer precursor model; on this basis, molecular dynamics simulation calculation is carried out, the influence law of the ratio change of fly ash and blast furnace slag on the macro mechanical properties and microstructure evolution of the material is systematically studied, and finally the inherent mechanism of performance regulation is revealed at the atomic scale.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a simulation-aided design method for polymer materials in iron tailings bases. Background Technology

[0002] With the continuous depletion of high-grade iron ore resources and the ongoing advancement of mineral processing technology, ultrafine iron tailings, as a major solid waste generated during mineral resource development, are experiencing a sustained and rapid increase in production. However, compared to its massive generation scale, the current comprehensive utilization rate remains low. Statistics show that approximately 1.4 billion tons of ultrafine iron tailings are added globally each year, with a cumulative stockpile exceeding 10 billion tons, but its resource utilization rate is less than 30%. Due to its extremely fine particle size, large specific surface area, easy agglomeration, and high moisture content, ultrafine iron tailings are difficult to use directly as traditional building aggregates or filler materials. Currently, its disposal method is still mainly tailings dam storage, which not only occupies a large amount of land resources but also poses safety hazards such as heavy metal leaching and dam failure under complex environmental conditions. Therefore, developing technological pathways for large-scale disposal and high-value utilization has become a critical issue that urgently needs to be addressed in the field of green mining and sustainable development.

[0003] Geopolymers, as a class of low-carbon and environmentally friendly alkali-activated cementitious materials, offer an important opportunity for the resource utilization of ultrafine iron tailings. These materials form an amorphous gel system with a three-dimensional network structure through a dissolution-reorganization reaction of silicon-aluminum sources in an alkaline environment, exhibiting both good mechanical properties and durability. However, due to the low reactivity of ultrafine iron tailings themselves, they are often difficult to polymerize effectively when used alone as precursors, typically requiring energy-intensive mechanical activation or thermal treatment to enhance their activity, which to some extent weakens their low-carbon advantages. Recent studies have shown that combining them with highly active auxiliary cementitious materials (such as fly ash and blast furnace slag) can significantly improve the reactivity and structural density of the system through chemical synergy and micro-filling effects, thus providing a feasible approach for the preparation of high-performance geopolymers and the large-scale utilization of tailings.

[0004] While existing research has made some progress in macroscopic mechanical properties and durability, a systematic and in-depth understanding of how the raw material ratio (especially the FA to GGBFS ratio) regulates the evolution of gel structure and its essential influence on material properties remains lacking. In recent years, research focus has gradually shifted from macroscopic performance characterization to macro-micro multi-scale correlation analysis. Against this backdrop, molecular dynamics simulations, as an atomic-scale computational method based on classical mechanics, can perform dynamic evolution and statistical analysis of large-scale particle systems, providing an important tool for revealing material structural evolution, bonding characteristics, and reaction mechanisms. Particularly in geopolymer systems, molecular dynamics simulations have been proven to effectively correlate microscopic structural parameters with macroscopic performance.

[0005] However, for geopolymer systems with high iron tailings content, there is still a lack of research that elucidates the intrinsic coupling relationship between proportion, structure, and performance at the atomic scale. In particular, there is a significant deficiency in the construction of cross-scale design theory. This research gap has, to some extent, restricted the accurate design and performance optimization of such materials. Summary of the Invention

[0006] In view of this, the present invention provides a simulation-aided design method for iron tailings base polymer materials, which comprehensively analyzes the influence of changes in the ratio of fly ash to blast furnace slag on the mechanical properties and structural evolution of the materials, and elucidates the performance regulation mechanism at the atomic scale.

[0007] In a first aspect, the present invention provides a simulation-aided design method for aggregate materials in iron tailings deposits, the method comprising:

[0008] Step 1: Define the basic assumptions and determine the force field; Step 2: Based on Step 1, determine the basic unit and construct the precursor model; Step 3: Based on step 2, perform molecular dynamics simulations.

[0009] Optionally, the basic assumptions in step 1 include: The hydration products of the fly ash-blast furnace slag base polymer are CASH and NASH. Based on the elemental composition of ultrafine iron tailings, fly ash, and blast furnace slag, their hydration product morphologies are basically the same, that is, ultrafine iron tailings and fly ash generate NASH, while blast furnace slag generates CASH. Therefore, the NASH:CASH ratio is used to replace the fly ash:blast furnace slag ratio for molecular dynamics simulation. First, two basic gel models, NASH and CASH, are established, and then they are combined at the molecular level to simulate the precursor structure with different blast furnace slag contents.

[0010] Optionally, the geopolymer comprises, by weight, 1000-2000 parts of iron tailings, 300-1500 parts of fly ash, 300-1500 parts of blast furnace slag, 80-200 parts of solid sodium hydroxide crystals, 100-200 parts of solid sodium silicate powder, and 1000-1500 parts of water. The iron tailings are composed of quartz, hematite, dolomite, chlorite, and calcium carbonate; the fly ash is grade F low-calcium fly ash, whose mineral composition includes quartz and mullite; the blast furnace slag is grade S95, with an activity index greater than or equal to 98%, and its mineral composition includes muscovite and calcium carbonate; the solid sodium hydroxide is in blocky crystal form with a purity greater than or equal to 97%; the solid sodium silicate is a white powder with a molar ratio of silicon dioxide to sodium oxide of 3.3. First, iron tailings, fly ash, and slag were dried to constant weight at 105±2℃ and their particle size distribution was measured after cooling. Second, the alkali activator was prepared by heating pure water to boiling and then cooling it to 60℃, dissolving sodium silicate and sodium hydroxide in sequence to prepare a solution with a SiO2 / Na2O molar ratio of 1.0~1.3. The solution was sealed and left to stand for 24 hours. Next, the dried solid raw materials were weighed according to the design ratio and dry-mixed evenly. After adding the alkali activator solution, the mixture was manually stirred for 1 minute, then stirred for 2 minutes at 60 r / min and 1 minute at 80 r / min using a cement mortar mixer. Finally, the mixture was manually stirred for 30 seconds to make it uniform, poured into a mold, and compacted for 1 minute. The specimens were demolded after standing at room temperature for 24 hours and then placed in a standard curing chamber at 60℃ and 98% relative humidity for 6 days.

[0011] Optionally, determining the force field in step 1 includes: Geopolymer systems are composed of metal oxides and non-metal oxides. The COMPASS force field is selected as the computational force field. The COMPASS force field is suitable for simulating condensed matter materials with well-defined three-dimensional networks or layered structures dominated by covalent / ionic bonds.

[0012] Optionally, determining the basic unit in step 2 includes: Using poly-sialate-siloxo model structural units from geopolymers as oligomer molecules for establishing the geopolymer model, charge balance of the overall structure was achieved by incorporating basic cations, ultimately yielding C / NASH gels. The basic constituent units of this gel include Ca, Na, H₂O, OH, and Si₂AlO₂. 10 The aforementioned basic units were established using the Monte Carlo method and implemented in DMol. 3 Module-optimized geometry.

[0013] Optionally, constructing the precursor model in step 2 includes: First, the proportions and density of NASH were determined based on the NASH model, where the proportions were Na / Al = 1, Si / Al = 2, H₂O / Na = 0.2, and the density was 1.04 g / cm³. 3 Secondly, CSH exhibits a molybdenum-like structure, and simulations were performed using an 11 Å molybdenum structure, Ca4Si6O14(OH)4·2H2O. A CSH model was constructed based on the Hamid model, and then Si was replaced with Al to achieve a density of 2.0 g / cm³. 3 NASH and CASH were mixed in different ratios to obtain the desired precursor models, ranging from 1:4 to 1:2. To ensure comparability, all gel models used a 1.5 g / cm³ gel. 3 The uniform density.

[0014] Optionally, step 3 includes: The precursor structure is energy and structurally unstable, requiring geometric optimization before molecular dynamics simulation. Optimization was performed sequentially in the Forcite module using the steepest descent method, conjugate gradient method, quasi-Newton method, and ABNR algorithm, with each algorithm executing a maximum of 1000 steps. Subsequently, the model underwent 100 ps molecular dynamics relaxation in the NPT and NVT ensembles at a time step of 1 fs to achieve system equilibrium and stability. The simulation was conducted with a cutoff radius of 12.5 Å under periodic boundary conditions.

[0015] The technical solution provided by this invention includes defining basic assumptions and determining the force field; determining basic units and constructing a precursor model; and performing molecular dynamics simulations. This method comprehensively analyzes the influence of changes in the ratio of fly ash to blast furnace slag on the mechanical properties and structural evolution of materials, and clarifies its performance regulation mechanism at the atomic scale. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating the simulation-aided design method for polymer materials in iron tailings ore deposits provided in this embodiment of the invention; Figure 2 A schematic diagram illustrating the process of constructing a tailings base polymer model according to an embodiment of the present invention; Figure 3 Particle size distribution diagrams of iron tailings, fly ash, and blast furnace slag provided for embodiments of the present invention; Figure 4 The tailings base aggregate model with optimized structure provided in the embodiments of the present invention includes, (a) the NASH model; (b) the CASH model; (c) the F1G4-M model; (d) the F1G2-M model; (e) the F1G1-M model; (f) the F2G1-M model; and (g) the F4G1-M model. Figure 5This is a schematic diagram of the simulated angle evolution provided in the embodiments of the present invention, wherein (a) is the O-Si-O angle evolution; (b) is the O-Al-O angle evolution; (c) is the HOH angle evolution; (d) is the Si-O-Al angle evolution; (e) is the Si-O-Al average angle evolution; (f) is the HOH average angle evolution; (g) is the O-Al-O average angle evolution; and (h) is the O-Si-O average angle evolution. Figure 6 A schematic diagram illustrating the evolution of elastic modulus and wave velocity in a simulated example provided in an embodiment of the present invention; Figure 7 A schematic diagram illustrating the mechanical strength of an experimental example provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the evolution of longitudinal wave velocity in an experimental example provided in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” used in the embodiments of this invention are also intended to include the plural forms unless the context clearly indicates otherwise.

[0020] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0021] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0022] This invention provides a simulation-aided design method for polymer materials in iron tailings ore deposits, such as... Figures 1 to 3 , Figure 4 (a) to (g) Figure 5 (a) to (h) and Figures 6 to 8 As shown, the method includes: In this embodiment of the invention, simulation examples 1-5 are as follows: A molecular model of a base polymer from iron tailings, named F1G4-M to F4G1-M, comprises the following raw material components in parts: Ca 100-400 parts, Na 100-400 parts, H2O 20-300 parts, OH 100-400 parts, and Si2AlO 10 50 to 500 samples, as shown in Table 1, representing the specific proportions of the simulation examples.

[0023] Table 1. Proportion of Simulation Examples .

[0024] Step 1: Define the basic assumptions and determine the force field.

[0025] In this embodiment of the invention, the basic assumptions in step 1 include: The hydration products of the fly ash-blast furnace slag base polymer are CASH and NASH. Based on the elemental composition of ultrafine iron tailings, fly ash, and blast furnace slag, their hydration product morphologies are basically the same, that is, ultrafine iron tailings and fly ash generate NASH, while blast furnace slag generates CASH. Therefore, the NASH:CASH ratio is used to replace the fly ash:blast furnace slag ratio for molecular dynamics simulation. First, two basic gel models, NASH and CASH, are established, and then they are combined at the molecular level to simulate the precursor structure with different blast furnace slag contents.

[0026] In this embodiment of the invention, the geopolymer comprises, by weight, 1000-2000 parts of iron tailings, 300-1500 parts of fly ash, 300-1500 parts of blast furnace slag, 80-200 parts of solid sodium hydroxide crystals, 100-200 parts of solid sodium silicate powder, and 1000-1500 parts of water. In this embodiment of the invention, Examples 1-5 have the following specific experimental proportions: Experimental Example 1 (F1G4-S): The amount of fly ash used was 300 grams, the amount of blast furnace slag was 1200 grams, the mass ratio of the two was 1:4, the amount of iron tailings used was 1500 grams, and the amount of water used was 1350 grams. The alkali activator consisted of 100 grams of sodium hydroxide and 183 grams of sodium silicate, and the modulus of the alkali activator was 1.2M.

[0027] Experimental Example 2 (F1G2-S): The amount of fly ash used was 500 grams, the amount of blast furnace slag was 1000 grams, the mass ratio was adjusted to 1:2, the amount of iron tailings used was 1500 grams, and the amount of water used was 1350 grams. The alkali activator consisted of 100 grams of sodium hydroxide and 183 grams of sodium silicate, and the modulus of the alkali activator was 1.2M.

[0028] Experimental Example 3 (F1G1-S): The amount of fly ash and blast furnace slag used was 750 grams each, achieving a 1:1 ratio. The amount of iron tailings used was 1500 grams, and the amount of water used was 1350 grams. The alkali activator consisted of 100 grams of sodium hydroxide and 183 grams of sodium silicate, and the modulus of the alkali activator was 1.2M.

[0029] Experimental Example 4 (F2G1-S): The amount of fly ash used was 1000 grams, the amount of blast furnace slag was 500 grams, the ratio of the two was 2:1, the amount of iron tailings used was 1500 grams, and the amount of water used was 1350 grams. The alkali activator was composed of 100 grams of sodium hydroxide and 183 grams of sodium silicate, and the modulus of the alkali activator was 1.2M.

[0030] Experimental Example 5 (F4G1-S): The amount of fly ash used was 1200 grams, the amount of blast furnace slag used was 300 grams, the ratio of the two was 4:1, the amount of iron tailings used was 1500 grams, and the amount of water used was 1350 grams. The alkali activator was composed of 100 grams of sodium hydroxide and 183 grams of sodium silicate, and the modulus of the alkali activator was 1.2M.

[0031] The iron tailings are composed of quartz, hematite, dolomite, chlorite, and calcium carbonate; the fly ash is grade F low-calcium fly ash, whose mineral composition includes quartz and mullite; the blast furnace slag is grade S95, with an activity index greater than or equal to 98%, and its mineral composition includes muscovite and calcium carbonate; the solid sodium hydroxide is in blocky crystal form with a purity greater than or equal to 97%; the solid sodium silicate is a white powder with a molar ratio (modulus) of silicon dioxide to sodium oxide of 3.3. The physicochemical properties of the iron tailings, fly ash, and blast furnace slag are as follows: ① Iron tailings; (1) Physical properties: The color is dark red and the specific gravity is 2.7.

[0032] (2) Chemical composition: Its main components are SiO2 (33.15%), Fe2O3 (19.11%), MgO (17.60%) and CaO (16.15%), and it also contains a certain amount of Al2O3 (10.78%). Its significant feature is its high iron and magnesium content, which gives it the potential to be used as an iron and magnesium correcting material and to provide some silicon and aluminum source.

[0033] ②Fly ash; (1) Physical properties: Light gray in color, density 2.10 g / cm³3 .

[0034] (2) Chemical composition: Its main components are SiO2 (45.10%) and Al2O3 (36.80%), which is a typical high-silicon, low-calcium (F grade) fly ash. Its aluminum content is particularly outstanding, making it a high-quality aluminum-silicon precursor raw material.

[0035] ③ Blast furnace slag; (1) Physical properties: The color is off-white, and the density is 3.1 g / cm³. 3 Its activity index is as high as 0.983, indicating that it has excellent potential gelling activity.

[0036] (2) Chemical composition: Its main components are CaO (34%), SiO2 (34.2%) and Al2O3 (17.6%), with a high calcium content. The high activity index, combined with its high calcium and high silicon-aluminum composition, makes it a key calcium-silicon-aluminum source that provides high reactivity and promotes early strength.

[0037] It is evident that the three types of solid waste complement each other in terms of composition: fly ash provides abundant silicon and aluminum elements, blast furnace slag contributes highly active calcium and silicon and aluminum sources, while iron tailings can provide some silicon and aluminum sources.

[0038] First, iron tailings, fly ash, and slag were dried to constant weight at 105±2℃ and their particle size distribution was measured after cooling. Second, the alkali activator was prepared by heating pure water to boiling and then cooling it to 60℃, dissolving sodium silicate and sodium hydroxide in sequence to prepare a solution with a SiO2 / Na2O molar ratio of 1.0~1.3. The solution was sealed and left to stand for 24 hours. Next, the dried solid raw materials were weighed according to the design ratio and dry-mixed evenly. After adding the alkali activator solution, the mixture was manually stirred for 1 minute, then stirred for 2 minutes at 60 r / min and 1 minute at 80 r / min using a cement mortar mixer. Finally, the mixture was manually stirred for 30 seconds to make it uniform, poured into a mold, and compacted for 1 minute. The specimens were demolded after standing at room temperature for 24 hours and then placed in a standard curing chamber at 60℃ and 98% relative humidity for 6 days.

[0039] In this embodiment of the invention, determining the force field in step 1 includes: Geopolymer systems are composed of metal oxides and non-metal oxides, belonging to the category of inorganic covalent bond systems in a broad sense. The COMPASS force field is selected as the computational force field. The COMPASS force field is suitable for simulating condensed matter materials with well-defined three-dimensional network or layered structure dominated by covalent / ionic bonds, such as aluminosilicates, oxides, ceramics and related geopolymer systems.

[0040] Step 2: Based on Step 1, determine the basic unit and construct the precursor model.

[0041] In this embodiment of the invention, determining the basic unit in step 2 includes: The poly-sialate-siloxo (PSS, -Si-O-Al-O-Si-O-) structural unit of geopolymers was used as the oligomer molecule for establishing the geopolymer model. By incorporating alkaline cations, charge balance of the overall structure was achieved, ultimately yielding C / NASH gel. The basic units of its composition include Ca, Na, H2O, OH, and Si2AlO. 10 The aforementioned basic units were established using the Monte Carlo method and implemented in DMol. 3 Module-optimized geometry.

[0042] In this embodiment of the invention, step 2, constructing the precursor model, includes: First, the proportions and density of NASH were determined based on the NASH model, where the proportions were Na / Al = 1, Si / Al = 2, H₂O / Na = 0.2, and the density was 1.04 g / cm³. 3 Secondly, CSH exhibits a molybdenum-like structure, and simulations were performed using an 11 Å molybdenum structure, Ca4Si6O14(OH)4·2H2O. A CSH model was constructed based on the Hamid model, and then Si was replaced with Al to achieve a density of 2.0 g / cm³. 3 NASH and CASH were mixed in different ratios to obtain the desired precursor models, ranging from 1:4 to 1:2. To ensure comparability, all gel models used a 1.5 g / cm³ gel. 3 The uniform density.

[0043] Step 3: Based on step 2, perform molecular dynamics simulations.

[0044] In this embodiment of the invention, step 3 includes: The precursor structure is energy and structurally unstable, requiring geometric optimization before molecular dynamics simulations. Optimization was performed sequentially in the Forcite module using the steepest descent method, conjugate gradient method, quasi-Newton method, and ABNR algorithm, with each algorithm executing a maximum of 1000 steps. Subsequently, the model underwent 100 ps molecular dynamics relaxation in the NPT and NVT ensembles at a time step of 1 fs to achieve system equilibrium and stability. The simulation was conducted at 12.5 Å (1 Å = 10⁻⁶ Å). -10 The cutoff radius (m) is used to operate under periodic boundary conditions.

[0045] This invention reveals the synergistic regulatory mechanism of fly ash to blast furnace slag ratio (FA:GGBFS) on the properties and structural evolution of iron tailings macropolymers. By establishing atomic models under different calcium contents and combining them with macroscopic mechanical tests, cross-scale correlation analysis from the atomic scale to macroscopic properties was achieved. Simulation results show that with the increase of the FA:GGBFS ratio, the elastic modulus and wave velocity of the system decrease, reflecting a weakening of structural stiffness. Simultaneously, a higher GGBFS content significantly shortens the bond lengths and bond angles of Si-Ob, Na-Ob, and Ca-Ob and reduces their distribution range, indicating enhanced interatomic interactions and a more compact and stable network structure. Experimental results are highly consistent with the simulation trends: with the increase of the FA ratio, the compressive strength, splitting strength, three-point bending strength, and ultrasonic velocity of the material all decrease significantly. Among them, the F1G4 group system exhibits the best performance, verifying the key role of Ca in promoting structural densification and enhancing mechanical properties.

[0046] Through a combined analysis of simulations and experiments, the multi-scale influence mechanism of raw material ratios on material properties was clarified: increasing FA content weakens the cross-linking degree of the gel structure, leading to a transformation of the system from a dense structure to a relatively loose structure, thus exhibiting a trend of performance degradation at the macro, micro, and nanoscale levels. Conversely, the Ca-rich system can promote a higher degree of structural reorganization and network construction, thereby significantly improving the overall material performance.

[0047] It should be noted that both molecular simulation and experimental methods have certain limitations: the former simplifies complex real-world systems in model construction, while the latter is constrained by testing conditions and experimental errors. However, the coupled application of the two forms an effective complementary mechanism. Simulation can identify key influencing factors in advance and guide formulation design, reducing experimental trial-and-error costs; experiments provide a basis for model verification and correction, thereby constructing a reliable multi-scale research framework.

[0048] At the methodological level, this invention first selects an applicable force field based on reasonable assumptions, constructs geopolymer precursor models under different proportions, and conducts molecular dynamics calculations to predict their structure and properties. Subsequently, it verifies and compares these models through systematic experiments, thereby establishing a quantitative correlation between proportions, structure, and properties. This strategy significantly improves material design efficiency and reduces R&D costs. At the engineering application level, this system uses iron tailings as the main component, co-utilizing fly ash and blast furnace slag, and forms high-performance cementitious materials through alkali activation, achieving synergistic high-value utilization of multi-source solid waste. This method not only helps reduce raw material consumption and production energy consumption but also effectively reduces the environmental risks caused by tailings storage, possessing significant economic, environmental, and social benefits. Overall, this technology provides a reliable path for the directional design and performance optimization of geopolymer materials, and is of great significance for promoting the resource utilization of solid waste and the low-carbon development of building materials.

[0049] This invention conducts multi-scale collaborative research and establishes a correlation mechanism from atomic structure to macroscopic properties, which has important theoretical significance and engineering application value for promoting the high-value utilization of ultrafine iron tailings base polymer materials.

[0050] The technical solution provided by this invention includes the following steps: first, defining the basic assumptions required for simulation and selecting a suitable force field; then, determining the basic chemical structural units of the system and constructing a corresponding geopolymer precursor model; based on this, conducting molecular dynamics simulation calculations to systematically study the influence of changes in the ratio of fly ash to blast furnace slag on the macroscopic mechanical properties and microstructural evolution of the material, and finally revealing the intrinsic mechanism of its performance regulation at the atomic scale. The above description is merely a preferred embodiment of this invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A simulation-aided design method for aggregate materials in iron tailings ore deposits, characterized in that, The method includes: Step 1: Define the basic assumptions and determine the force field; Step 2: Based on Step 1, determine the basic unit and construct the precursor model; Step 3: Based on step 2, perform molecular dynamics simulations.

2. The method according to claim 1, characterized in that, The basic assumptions in step 1 include: The hydration products of the fly ash-blast furnace slag base polymer are CASH and NASH. Based on the elemental composition of ultrafine iron tailings, fly ash, and blast furnace slag, their hydration product morphologies are basically the same, that is, ultrafine iron tailings and fly ash generate NASH, while blast furnace slag generates CASH. Therefore, the NASH:CASH ratio is used to replace the fly ash:blast furnace slag ratio for molecular dynamics simulation. First, two basic gel models, NASH and CASH, are established, and then they are combined at the molecular level to simulate the precursor structure with different blast furnace slag contents.

3. The method according to claim 2, characterized in that, The geopolymer comprises, by weight, 1000-2000 parts of iron tailings, 300-1500 parts of fly ash, 300-1500 parts of blast furnace slag, 80-200 parts of solid sodium hydroxide crystals, 100-200 parts of solid sodium silicate powder, and 1000-1500 parts of water. The iron tailings are composed of quartz, hematite, dolomite, chlorite, and calcium carbonate; the fly ash is grade F low-calcium fly ash, whose mineral composition includes quartz and mullite; the blast furnace slag is grade S95, with an activity index greater than or equal to 98%, and its mineral composition includes muscovite and calcium carbonate; the solid sodium hydroxide is in blocky crystal form with a purity greater than or equal to 97%; the solid sodium silicate is a white powder with a molar ratio of silicon dioxide to sodium oxide of 3.

3. First, iron tailings, fly ash, and slag were dried to constant weight at 105±2℃ and their particle size distribution was measured after cooling. Second, the alkali activator was prepared by heating pure water to boiling and then cooling it to 60℃, dissolving sodium silicate and sodium hydroxide in sequence to prepare a solution with a SiO2 / Na2O molar ratio of 1.0~1.

3. The solution was sealed and left to stand for 24 hours. Next, the dried solid raw materials were weighed according to the design ratio and dry-mixed evenly. After adding the alkali activator solution, the mixture was manually stirred for 1 minute, then stirred for 2 minutes at 60 r / min and 1 minute at 80 r / min using a cement mortar mixer. Finally, the mixture was manually stirred for 30 seconds to make it uniform, poured into a mold, and compacted for 1 minute. The specimens were demolded after standing at room temperature for 24 hours and then placed in a standard curing chamber at 60℃ and 98% relative humidity for 6 days.

4. The method according to claim 2, characterized in that, Determining the force field in step 1 includes: Geopolymer systems are composed of metal oxides and non-metal oxides. The COMPASS force field is selected as the computational force field. The COMPASS force field is suitable for simulating condensed matter materials with well-defined three-dimensional networks or layered structures dominated by covalent / ionic bonds.

5. The method according to claim 4, characterized in that, Determining the basic unit in step 2 includes: Using poly-sialate-siloxo model structural units from geopolymers as oligomer molecules for establishing the geopolymer model, charge balance of the overall structure was achieved by incorporating basic cations, ultimately yielding C / NASH gels. The basic constituent units of this gel include Ca, Na, H₂O, OH, and Si₂AlO₂. 10 The aforementioned basic units were established using the Monte Carlo method and implemented in DMol. 3 Module-optimized geometry.

6. The method according to claim 5, characterized in that, Step 2, which involves constructing the precursor model, includes: First, the proportions and density of NASH were determined based on the NASH model, where the proportions were Na / Al = 1, Si / Al = 2, H₂O / Na = 0.2, and the density was 1.04 g / cm³. 3 Secondly, CSH exhibits a molybdenum-like structure, and simulations were performed using an 11 Å molybdenum structure, Ca4Si6O14(OH)4·2H2O. A CSH model was constructed based on the Hamid model, and then Si was replaced with Al to achieve a density of 2.0 g / cm³. 3 NASH and CASH were mixed in different ratios to obtain the desired precursor models, ranging from 1:4 to 1:

2. To ensure comparability, all gel models used a 1.5 g / cm³ gel. 3 The uniform density.

7. The method according to claim 6, characterized in that, Step 3 includes: The precursor structure is energy and structurally unstable, requiring geometric optimization before molecular dynamics simulation. Optimization was performed sequentially in the Forcite module using the steepest descent method, conjugate gradient method, quasi-Newton method, and ABNR algorithm, with each algorithm executing a maximum of 1000 steps. Subsequently, the model underwent 100 ps molecular dynamics relaxation in the NPT and NVT ensembles at a time step of 1 fs to achieve system equilibrium and stability. The simulation was conducted with a cutoff radius of 12.5 Å under periodic boundary conditions.

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