Iron tailings based polymer simulation aided design method

Abstract

The present application relates to solid waste resource utilization technical field, especially provide a kind of iron tailings base polymer simulation aided design method.The method includes defining basic assumption, and determine force field;Determine the basic unit, and construct precursor model;Molecular dynamics simulation is carried out, the method comprehensively analyzes the influence law of the change of fly ash and blast furnace slag ratio on material mechanical properties and structural evolution, and clarifies its performance regulation mechanism from atomic scale level.

Description

Technical Field

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

[0002] With the depletion of high-grade iron ore and advancements in mineral processing technology, ultrafine iron tailings, a major solid waste generated after the extraction of valuable components, have seen a surge in production but low utilization rates. Their fine particle size, large specific surface area, tendency to agglomerate, and high moisture content limit their traditional uses, such as as building aggregate. Currently, ultrafine iron tailings are mostly stored in tailings ponds, encroaching on land resources and posing environmental pollution and dam failure risks. Therefore, improving their resource utilization rate is urgently needed.

[0003] Geopolymers are low-carbon, alkali-activated cementitious materials that offer a new approach to the resource utilization of ultrafine iron tailings. However, ultrafine iron tailings themselves have low chemical reactivity, and using them alone as silica-alumina precursors often requires energy-intensive grinding or calcination pretreatment, which contradicts the concept of sustainable development. Research shows that combining ultrafine iron tailings with highly reactive fly ash and blast furnace slag can significantly enhance the reactivity of geopolymers through a synergistic effect, thereby preparing high-performance tailings-based geopolymers. This approach provides a potential solution for the large-scale disposal of ultrafine iron tailings, the realization of high-value utilization of solid waste, and the promotion of the green transformation of building materials.

[0004] To gain a deeper understanding of the microscopic influence of raw material ratios (especially fly ash: blast furnace slag) on ​​the structure of geopolymer gels, current research is trending towards combining macroscopic performance testing with microscopic characterization techniques. Molecular dynamics simulations, as an atomic-scale computational method, can simulate and statistically analyze large particle systems based on Newtonian mechanics, and have become an important research tool for revealing geopolymer reaction mechanisms and bridging macroscopic properties and microscopic structures. Currently, nanoscale research on geopolymer reaction mechanisms, especially work establishing macroscopic-microscopic-atomic scale correlations, is still relatively lacking. Summary of the Invention

[0005] In view of this, the present invention provides a polymer simulation-assisted design method for iron tailings bases, which is used to comprehensively analyze the influence of changes in the ratio of fly ash to blast furnace slag on the mechanical properties and structural evolution of materials, and to elucidate the performance regulation mechanism at the atomic scale.

[0006] In a first aspect, the present invention provides a method for polymer simulation-aided design of iron tailings bases, the method comprising:

[0007] 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.

[0008] Optionally, the basic assumptions in step 1 include: The hydration products of the fly ash-blast furnace slag 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 consistent: ultrafine iron tailings and fly ash generate NASH, while blast furnace slag generates CASH. The hydration products NASH and CASH are integrated into a unified C / NASH framework. The gel structure used is an idealized end-member model, which cannot fully reflect the chemical coupling phenomena in the actual polymer system. Molecular dynamics simulations were used to study the nanoscale structure, ion transport behavior, and short-range order of the dominant gel phase. The basic structural unit method was used to construct... A molecular model of the geopolymer was established. To ensure consistency with the experimental mix proportions, the Ca / Si, Si / Al, and Na / Al ratios in the raw materials were calculated. Inert calcite present in iron tailings was not included in the Ca / Si ratio calculation. Water plays a role in the geopolymer system as both a physical carrier (dissolving, mass transfer, and enhancing processability) and a participant in chemical reactions (providing reactive ions and shaping the microstructure). Precise control of its amount is key to balancing the flowability, reactivity, and final mechanical properties of the geopolymer. A basic gel model was established based on the raw material proportions, and then the models were combined at the molecular level to simulate the precursor structures with different blast furnace slag contents.

[0009] Optionally, the geopolymer comprises, by weight, 3000-6000 parts of iron tailings, 300-1500 parts of fly ash, 300-1500 parts of blast furnace slag, 200-400 parts of sodium hydroxide crystals, 500-1200 parts of sodium silicate powder, and 2000-3000 parts of water. The iron tailings contain quartz, hematite, dolomite, chlorite, and calcium carbonate; the fly ash is grade F low-calcium fly ash, containing quartz and mullite; the blast furnace slag is grade S95 with an activity index greater than or equal to 98%, containing muscovite and calcium carbonate; the sodium hydroxide is crystalline with a purity greater than or equal to 97%; and the sodium silicate is powder with a molar ratio of silicon dioxide to sodium oxide of 3.0 to 3.6. First, iron tailings, fly ash, and slag were dried to constant weight at 105±5℃ 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 60~70℃, dissolving sodium silicate and sodium hydroxide in sequence to prepare a solution with a SiO2 / Na2O molar ratio of 1.4. The solution was sealed and allowed to stand for 20~30 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 2~3 minutes, and then stirred for 2 minutes at 60~70 r / min and 1 minute at 100~120 r / min using a cement mortar mixer. Finally, the mixture was manually stirred for 1~2 minutes to make it uniform, poured into a mold, and compacted for 1~2 minutes. The specimens were demolded after standing at room temperature for 24 hours and then placed in a standard curing chamber at 60℃ and 95~98% relative humidity for 6 days.

[0010] 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.

[0011] Optionally, determining the basic unit in step 2 includes: Using poly-sialate-siloxo and poly-sialate-disiloxo model structural units from geopolymers as oligomer molecules for establishing the geopolymer model, charge balance of the overall structure was achieved by incorporating alkaline cations, ultimately yielding C / NASH gels. The basic units of these gels include Ca, Na, H₂O, OH, and Si₂AlO₂. 10 Si3AlO 13 The aforementioned basic units were established using the Monte Carlo method and implemented in DMol. 3 The module's geometry was optimized; to ensure computational reliability, the cell size of the constructed polymer model was greater than 25Å×25Å×25Å.

[0012] Optionally, constructing the precursor model in step 2 includes: First, the Ca / Si, Si / Al, and Na / Al ratios and densities of the gel model were determined based on the raw material proportions. Inert calcite present in the iron tailings was not included in the Ca / Si ratio calculation. The density of the gel model was input based on the actual measured gel density. Second, the 11Å-type torbure-mullite structure (Ca...) 4.5 Si6O 16(OH)·5H₂O), corresponding to H₂O / (Si+Al) = 5 / 6; based on the above parameters, two aluminosilicate structural units are introduced into the model, with Si / Al ratios of 2 and 3, respectively; in the aluminosilicate framework, aluminum replaces silicon to form negatively charged [AlO₄]. - Group.

[0013] Optionally, step 3 includes: To eliminate the instability of the initial configuration and obtain the equilibrium structure, the following molecular dynamics simulation scheme was adopted: First, multi-level geometric optimization was performed on the precursor model: in the Forcite module, the steepest descent method, conjugate gradient method, quasi-Newton method, and ABNR method were used sequentially, each algorithm executing 10,000 steps to fully relax the structure and reduce the potential energy; then, annealing was performed under the NVT ensemble, cycling the system 10 times between 298K and 2500K, with 10,000 steps per cycle and a step size of 0.5 fs, to cross the energy barrier, promote global relaxation, and eliminate residual stress; after that, a two-step equilibrium simulation was performed with a step size of 1.0 fs: first, a 500 ps NPT simulation was performed at 298K and 1 atm to fully relax the system density; then, a 500 ps NVT simulation was performed at 298K for subsequent structural analysis; the cutoff radius for all interactions was set to 12.5. .

[0014] 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

[0015] 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.

[0016] Figure 1 A flowchart of the polymer simulation-aided design method for iron tailings bases 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 4The tailings base aggregate model with optimized structure provided in the embodiments of the present invention is as follows: (a) is the F1G2-M model; (b) is the F2G3-M model; (c) is the F3G4-M model; (d) is the F4G4-M model; (e) is the F4G3-M model; (f) is the F3G2-M model; and (g) is the F2G1-M model. Figure 5 This 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 Si-O-Al angle evolution; (d) is the HOH angle evolution; and (e) is the average angle evolution. Figure 6 A schematic diagram of a simulation example provided in an embodiment of the present invention, wherein (a) represents wave velocity evolution; and (b) represents elastic modulus. Figure 7 This is a schematic diagram of the mechanical strength of an experimental example provided in an embodiment of the present invention, wherein (a) is the uniaxial compressive strength; (b) is the Brazilian splitting strength; and (c) is the three-point bending strength. 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

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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)."

[0021] This invention provides a polymer simulation-aided design method for iron tailings bases, such as... Figures 1 to 3 , Figure 4 (a) to (g) Figure 5 (a) to (e) Figure 6 (a) and (b) Figure 7 (a) to (c) and Figure 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 F1G2-M to F2G1-M, comprises the following raw material components in parts: Ca 10-40 parts, Na 30-40 parts, H2O 150-170 parts, OH 1-50 parts, and Si2AlO 10 40-60 parts, Si3AlO 13 1 to 20 samples, as shown in Table 1, representing the specific proportions of the simulation examples.

[0022] Table 1. Proportion of Simulation Examples .

[0023] Step 1: Define the basic assumptions and determine the force field.

[0024] In this embodiment of the invention, the basic assumptions in step 1 include: The hydration products of the fly ash-blast furnace slag 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 consistent: ultrafine iron tailings and fly ash generate NASH, while blast furnace slag generates CASH. The hydration products NASH and CASH are integrated into a unified C / NASH framework. The gel structure used is an idealized end-member model, which cannot fully reflect the chemical coupling phenomena in the actual polymer system. Molecular dynamics simulations were used to study the nanoscale structure, ion transport behavior, and short-range order of the dominant gel phase. The basic structural unit method was used to construct... A molecular model of the geopolymer was established. To ensure consistency with the experimental mix proportions, the Ca / Si, Si / Al, and Na / Al ratios in the raw materials were calculated. Inert calcite present in iron tailings was not included in the Ca / Si ratio calculation. Water plays a role in the geopolymer system as both a physical carrier (dissolving, mass transfer, and enhancing processability) and a participant in chemical reactions (providing reactive ions and shaping the microstructure). Precise control of its amount is key to balancing the flowability, reactivity, and final mechanical properties of the geopolymer. A basic gel model was established based on the raw material proportions, and then the models were combined at the molecular level to simulate the precursor structures with different blast furnace slag contents.

[0025] In this embodiment of the invention, the geopolymer comprises, by weight, 3000-6000 parts of iron tailings, 300-1500 parts of fly ash, 300-1500 parts of blast furnace slag, 200-400 parts of sodium hydroxide crystals, 500-1200 parts of sodium silicate powder, and 2000-3000 parts of water. In this embodiment of the invention, Examples 1-5 have the following specific experimental proportions: Experimental Example 1 (F1G2-S): The amount of fly ash used was 800 parts, the amount of blast furnace slag was 1600 parts, the mass ratio of the two was 1:2, the amount of iron tailings used was 3600 parts, and the amount of water used was 2520 parts. The alkali activator was composed of 271.5 parts of sodium hydroxide and 640.5 parts of sodium silicate, and the modulus of the alkali activator was 1.4M.

[0026] Experimental Example 2 (F2G3-S): The amount of fly ash was 960 parts, the amount of blast furnace slag was 1440 parts, the mass ratio was adjusted to 2:3, the amount of iron tailings was 3600 parts, and the amount of water was 2520 parts. The alkali activator consisted of 271.5 parts of sodium hydroxide and 640.5 parts of sodium silicate, and the modulus of the alkali activator was 1.4M.

[0027] Experimental Example 3 (F3G4-S): The amount of fly ash was 1030 parts, the amount of blast furnace slag was 1370 parts, the mass ratio was adjusted to 3:4, the amount of iron tailings was 3600 parts, and the amount of water was 2520 parts. The alkali activator consisted of 271.5 parts of sodium hydroxide and 640.5 parts of sodium silicate, and the modulus of the alkali activator was 1.4M.

[0028] Experimental Example 4 (F4G4-S): The amount of fly ash and blast furnace slag used was 1200 parts each, achieving a 1:1 ratio. The amount of iron tailings used was 3600 parts, and the amount of water used was 2520 parts. The alkali activator consisted of 271.5 parts of sodium hydroxide and 640.5 parts of sodium silicate, and the modulus of the alkali activator was 1.4M.

[0029] Experimental Example 5 (F4G3-S): The amount of fly ash was 1370 parts, the amount of blast furnace slag was 1030 parts, the ratio of the two was 4:3, the amount of iron tailings was 3600 parts, and the amount of water was 2520 parts. The alkali activator was composed of 271.5 parts of sodium hydroxide and 640.5 parts of sodium silicate, and the modulus of the alkali activator was 1.4M.

[0030] Experimental Example 6 (F3G2-S): The amount of fly ash used was 1440 parts, the amount of blast furnace slag was 960 parts, the ratio of the two was 3:2, the amount of iron tailings used was 3600 parts, and the amount of water used was 2520 parts. The alkali activator was composed of 271.5 parts of sodium hydroxide and 640.5 parts of sodium silicate, and the modulus of the alkali activator was 1.4M.

[0031] Experimental Example 7 (F2G1-S): The amount of fly ash used was 1600 parts, the amount of blast furnace slag was 800 parts, the ratio of the two was 2:1, the amount of iron tailings used was 3600 parts, and the amount of water used was 2520 parts. The alkali activator was composed of 271.5 parts of sodium hydroxide and 640.5 parts of sodium silicate, and the modulus of the alkali activator was 1.4M.

[0032] The iron tailings contain quartz, hematite, dolomite, chlorite, and calcium carbonate; the fly ash is grade F low-calcium fly ash, containing quartz and mullite; the blast furnace slag is grade S95 with an activity index greater than or equal to 98%, containing muscovite and calcium carbonate; the sodium hydroxide is crystalline with a purity greater than or equal to 97%; and the sodium silicate is powder with a molar ratio of silicon dioxide to sodium oxide of 3.0 to 3.6. 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.

[0033] (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.

[0034] ② Fly ash; (1) Physical properties: Light gray in color, density 2.10 g / cm³ 3 .

[0035] (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.

[0036] 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.

[0037] (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.

[0038] 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.

[0039] First, iron tailings, fly ash, and slag were dried to constant weight at 105±5℃ 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 60~70℃, dissolving sodium silicate and sodium hydroxide in sequence to prepare a solution with a SiO2 / Na2O molar ratio of 1.4. The solution was sealed and allowed to stand for 20~30 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 2~3 minutes, and then stirred for 2 minutes at 60~70 r / min and 1 minute at 100~120 r / min using a cement mortar mixer. Finally, the mixture was manually stirred for 1~2 minutes to make it uniform, poured into a mold, and compacted for 1~2 minutes. The specimens were demolded after standing at room temperature for 24 hours and then placed in a standard curing chamber at 60℃ and 95~98% relative humidity for 6 days.

[0040] 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.

[0041] Step 2: Based on Step 1, determine the basic unit and construct the precursor model.

[0042] In this embodiment of the invention, determining the basic unit in step 2 includes: Using poly-sialate-siloxo and poly-sialate-disiloxo model structural units from geopolymers as oligomer molecules for establishing the geopolymer model, charge balance of the overall structure was achieved by incorporating alkaline cations, ultimately yielding C / NASH gels. The basic units of these gels include Ca, Na, H₂O, OH, and Si₂AlO₂. 10 Si3AlO 13 The aforementioned basic units were established using the Monte Carlo method and implemented in DMol. 3 The module's geometry was optimized; to ensure computational reliability, the cell size of the constructed polymer model was greater than 25Å×25Å×25Å.

[0043] In this embodiment of the invention, step 2, constructing the precursor model, includes: First, the Ca / Si, Si / Al, and Na / Al ratios and densities of the gel model were determined based on the raw material ratios. Inert calcite present in the iron tailings was not included in the Ca / Si ratio calculation. The proportions of each element in the geopolymer are shown in Table 2. Furthermore, the density of the gel model was input based on the actual measured gel density. Second, the 11Å-type torbure-mullite structure (Ca...) 4.5 Si6O 16 (OH)·5H2O), corresponding to H2O / (Si+Al)=5 / 6; based on the above parameters, two aluminosilicate structural units are introduced into the model, with Si / Al ratios of 2 and 3 respectively (poly-sialate-siloxo, PSS: -Si-O-Al-O-Si-O-; poly-sialate-disiloxo, PSDS: -Si-O-Al-O-Si-O-Si-O-); in the aluminosilicate framework, aluminum replaces silicon to form negatively charged [AlO4]. - Group.

[0044] Table 2. Proportions of elements in geopolymers .

[0045] Step 3: Based on step 2, perform molecular dynamics simulations.

[0046] In this embodiment of the invention, step 3 includes: To eliminate the instability of the initial configuration and obtain the equilibrium structure, the following molecular dynamics simulation scheme was adopted: First, multi-level geometric optimization was performed on the precursor model: in the Forcite module, the steepest descent method, conjugate gradient method, quasi-Newton method, and ABNR method were used sequentially, each algorithm executing 10,000 steps to fully relax the structure and reduce the potential energy; then, annealing was performed under the NVT ensemble, cycling the system 10 times between 298K and 2500K, with 10,000 steps per cycle and a step size of 0.5 fs, to cross the energy barrier, promote global relaxation, and eliminate residual stress; after that, a two-step equilibrium simulation was performed with a step size of 1.0 fs: first, a 500 ps NPT simulation was performed at 298K and 1 atm to fully relax the system density; then, a 500 ps NVT simulation was performed at 298K for subsequent structural analysis; the cutoff radius for all interactions was set to 12.5. This process ensures the energy convergence and structural stability of the system, providing a reliable equilibrium trajectory for subsequent property analysis.

[0047] In this invention, by combining molecular dynamics simulations and experiments, the effects of the fly ash:blast furnace slag ratio on the physical and mechanical properties and molecular configuration of iron tailings macropolymers were systematically investigated. This research method, combining macroscopic, microscopic, and nanoscale approaches, provides new insights for advancing the development of iron tailings macropolymers. Molecular dynamics simulations showed that increasing the fly ash:blast furnace slag ratio reduced the elastic modulus and wave velocity of the simulated iron tailings macropolymer. Furthermore, increasing the blast furnace slag content shortened the Si-O, Na-O, and Ca-O bond lengths and bond angles, while also reducing their distribution range, indicating enhanced interatomic interactions and improved three-dimensional network stability. Specific experimental results showed that increasing the fly ash:blast furnace slag ratio significantly reduced its mechanical strength and wave velocity. Among all the mixed systems, the F1G2 combination performed best (uniaxial compressive strength 30.37 MPa; Brazilian splitting strength 1.70 MPa; three-point flexural strength 1.51 MPa), while the F2G1 combination performed worst.

[0048] By correlating molecular dynamics simulations with experimental results, the macro- and micro-level effects of the fly ash:blast furnace slag ratio on iron tailings geopolymers can be effectively explained. Overall, an increase in the fly ash:blast furnace slag ratio leads to structural degradation of the geopolymer, manifested as a decline in macro-, micro-, and nanoscale physical and mechanical properties. The F1G2 structure exhibits the best performance and warrants further investigation for practical engineering applications.

[0049] It should be noted that molecular simulation and experimental methods each have their limitations. The former simplifies the simulation of complex states of real materials, while the latter is affected by testing conditions and random errors. However, the two can form a complementary multi-scale closed loop: simulation can proactively reveal key influencing factors (such as the positive role of calcium ions in this study), providing clear guidance for experimental design and significantly reducing the blind spots and trial-and-error costs of research; while experimental results can calibrate simulation parameters, verify models, and suggest new research directions. Through this synergistic strategy, this invention achieves effective prediction and optimization of the properties of geopolymers under different raw material ratios, providing a powerful tool and reference for the efficient design and performance control of materials.

[0050] This invention presents a novel method for preparing geopolymer cementitious materials, primarily using iron tailings, in conjunction with fly ash and blast furnace slag, and employing sodium hydroxide and sodium silicate as alkali activators. By combining molecular dynamics simulations with systematic experimental studies, the influence of varying fly ash and blast furnace slag ratios on the mechanical properties and structural evolution of the materials was comprehensively analyzed, and the performance regulation mechanism was elucidated at the atomic scale. This method not only contributes to a deeper understanding of the microstructural characteristics and evolution mechanism of iron tailings geopolymers but also allows for the prospective optimization of experimental ratios using simulation results, providing theoretical guidance for material design and performance regulation, thereby significantly shortening the research and development cycle and improving the overall performance of the materials. Simultaneously, this system provides a feasible path for the synergistic high-value utilization of various industrial solid wastes such as fly ash, blast furnace slag, and iron tailings, reducing resource consumption and production costs while helping to reduce environmental impact, which is of great significance for promoting the low-carbon development of the building materials field.

[0051] This invention constructs geopolymer models with varying calcium contents using molecular dynamics simulations to predict their performance. It also leverages the synergistic effect of iron tailings, fly ash, and blast furnace slag to regulate the performance of geopolymer materials by adjusting the ratio of fly ash to blast furnace slag. Experimental results demonstrate that this simulation method effectively guides raw material ratio adjustments, significantly reducing R&D costs and time. The resulting iron tailings-based geopolymers can be applied in a tiered and categorized manner, efficiently utilizing multi-source solid waste such as iron tailings, fly ash, and slag while substantially reducing carbon emissions and production costs, providing crucial technological support for the green transformation of the mining and building materials industries.

[0052] This invention employs a simulation-guided experimental approach. First, it constructs atomic models of geopolymers with different fly ash / blast furnace slag ratios using molecular dynamics simulations and predicts their mechanical properties. Then, it verifies the simulation results through systematic experiments. This method reveals the relationship between raw material ratios and macroscopic properties, significantly reducing the extensive experimental work and resource consumption associated with traditional trial-and-error methods. It provides a reliable theoretical basis and efficient technical path for the targeted design and formulation optimization of high-performance geopolymer materials. Specifically, economically, it significantly reduces raw material and energy costs by utilizing industrial solid waste and improves R&D efficiency through simulation-aided design. Environmentally, it achieves carbon emission reduction and synergistic resource utilization of bulk solid waste, reducing source pollution and accumulation risks. Socially, it promotes green industrial transformation and reduces safety hazards around tailings ponds, forming a sustainable material solution that unifies economic, environmental, and social benefits.

[0053] 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 rheological properties, mechanical properties, and structural evolution of materials, and elucidates the performance regulation mechanism at the atomic scale.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for aggregate simulation-aided design of iron tailings bases, 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 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 consistent: ultrafine iron tailings and fly ash generate NASH, while blast furnace slag generates CASH. The hydration products NASH and CASH are integrated into a unified C / NASH framework. The gel structure used is an idealized end-member model, which cannot fully reflect the chemical coupling phenomena in the actual polymer system. Molecular dynamics simulations were used to study the nanoscale structure, ion transport behavior, and short-range order of the dominant gel phase. The basic structural unit method was used to construct... A molecular model of the geopolymer was established. To ensure consistency with the experimental mix proportions, the Ca / Si, Si / Al, and Na / Al ratios in the raw materials were calculated. Inert calcite present in iron tailings was not included in the Ca / Si ratio calculation. Water plays a role in the geopolymer system as both a physical carrier (dissolving, mass transfer, and enhancing processability) and a participant in chemical reactions (providing reactive ions and shaping the microstructure). Precise control of its amount is key to balancing the flowability, reactivity, and final mechanical properties of the geopolymer. A basic gel model was established based on the raw material proportions, and then the models were combined at the molecular level to simulate the precursor structures with different blast furnace slag contents.

3. The method according to claim 2, characterized in that, The geopolymer comprises, by weight, 3000-6000 parts of iron tailings, 300-1500 parts of fly ash, 300-1500 parts of blast furnace slag, 200-400 parts of sodium hydroxide crystals, 500-1200 parts of sodium silicate powder, and 2000-3000 parts of water. The iron tailings contain quartz, hematite, dolomite, chlorite, and calcium carbonate; the fly ash is grade F low-calcium fly ash, containing quartz and mullite; the blast furnace slag is grade S95 with an activity index greater than or equal to 98%, containing muscovite and calcium carbonate; the sodium hydroxide is crystalline with a purity greater than or equal to 97%; and the sodium silicate is powder with a molar ratio of silicon dioxide to sodium oxide of 3.0 to 3.

6. First, iron tailings, fly ash, and slag were dried to constant weight at 105±5℃ 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 60~70℃, dissolving sodium silicate and sodium hydroxide in sequence to prepare a solution with a SiO2 / Na2O molar ratio of 1.

4. The solution was sealed and allowed to stand for 20~30 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 2~3 minutes, and then stirred for 2 minutes at 60~70 r / min and 1 minute at 100~120 r / min using a cement mortar mixer. Finally, the mixture was manually stirred for 1~2 minutes to make it uniform, poured into a mold, and compacted for 1~2 minutes. The specimens were demolded after standing at room temperature for 24 hours and then placed in a standard curing chamber at 60℃ and 95~98% 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 and poly-sialate-disiloxo model structural units from geopolymers as oligomer molecules for establishing the geopolymer model, charge balance of the overall structure was achieved by incorporating alkaline cations, ultimately yielding C / NASH gels. The basic units of these gels include Ca, Na, H₂O, OH, and Si₂AlO₂. 10 Si3AlO 13 The aforementioned basic units were established using the Monte Carlo method and implemented in DMol. 3 The module's geometry was optimized; to ensure computational reliability, the cell size of the constructed polymer model was greater than 25Å×25Å×25Å.

6. The method according to claim 5, characterized in that, Step 2, which involves constructing the precursor model, includes: First, the Ca / Si, Si / Al, and Na / Al ratios and densities of the gel model were determined based on the raw material proportions. Inert calcite present in the iron tailings was not included in the Ca / Si ratio calculation. The density of the gel model was input based on the actual measured gel density. Second, the 11Å-type torbure-mullite structure (Ca...) 4.5 Si6O 16 (OH)·5H₂O), corresponding to H₂O / (Si+Al) = 5 / 6; based on the above parameters, two aluminosilicate structural units are introduced into the model, with Si / Al ratios of 2 and 3, respectively; in the aluminosilicate framework, aluminum replaces silicon to form negatively charged [AlO₄]. - Group.

7. The method according to claim 6, characterized in that, Step 3 includes: To eliminate the instability of the initial configuration and obtain the equilibrium structure, the following molecular dynamics simulation scheme was adopted: First, multi-level geometric optimization was performed on the precursor model: in the Forcite module, the steepest descent method, conjugate gradient method, quasi-Newton method, and ABNR method were used sequentially, each algorithm executing 10,000 steps to fully relax the structure and reduce the potential energy; then, annealing was performed under the NVT ensemble, cycling the system 10 times between 298K and 2500K, with 10,000 steps per cycle and a step size of 0.5 fs, to cross the energy barrier, promote global relaxation, and eliminate residual stress; after that, a two-step equilibrium simulation was performed with a step size of 1.0 fs: first, a 500 ps NPT simulation was performed at 298K and 1 atm to fully relax the system density; then, a 500 ps NVT simulation was performed at 298K for subsequent structural analysis; the cutoff radius for all interactions was set to 12.

5. .

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