Modified desulfurized gypsum alkali-activated manganese tailings-based polymer, preparation method and application thereof

Abstract

The application relates to the technical field of industrial solid waste resource utilization, and particularly discloses a modified alkali-activated manganese tailing-based polymer prepared from desulfurization gypsum and a preparation method and application thereof, wherein the liquid-solid ratio of the alkali-activator to the solid component is 47.5-52.5%; the solid component comprises 90-98 wt% of activated manganese tailing and 2-10 wt% of desulfurization gypsum; the alkali-activator comprises 6-10 wt% of sodium oxide equivalent alkali based on the mass of the solid component, and the alkali-activator comprises water glass, sodium hydroxide and deionized water, and the modulus of the water glass is 1.2-1.8. The manganese tailing is ball milled, and is combined with the alkali-activator, so that the two types of industrial solid waste resources are utilized, the industrial by-product desulfurization gypsum is consumed simultaneously while a large amount of abandoned manganese tailing is treated and stored, and thus the problems of low alkali-activation activity of the manganese tailing, high risk of sulfate leaching and low utilization rate of solid waste in the prior art are solved.

Description

Technical Field

[0001] This application relates to the field of industrial solid waste resource utilization technology, and more specifically, it relates to desulfurized gypsum-modified alkali-activated manganese tailings-based polymer, its preparation method, and its application. Background Technology

[0002] Manganese tailings are a large amount of industrial solid waste generated during manganese ore beneficiation, characterized by their large volume, extensive storage area, and high environmental risk. Manganese tailings contain a large amount of soluble sulfates, which are easily leached and migrated under the action of rainfall, causing ecological and environmental problems such as soil salinization and excessive sulfate levels in groundwater. Furthermore, the main crystalline phases of manganese tailings are quartz, gypsum, and pyrite, which are structurally stable and have low alkali-activated reactivity. They are difficult to use directly as polymer precursors to form a dense cementitious system, exhibiting defects such as low early strength, loose structure, and poor ion solidification effect.

[0003] Alkali-activated polymers are low-carbon gelling materials that react aluminosilicate precursors with alkali activators to form a three-dimensional network gel, enabling the physical encapsulation and chemical stabilization of harmful components such as heavy metals and sulfates. However, for low-activity manganese tailings systems, simple alkali activation is insufficient to meet engineering application requirements.

[0004] Desulfurized gypsum is a solid waste byproduct of flue gas desulfurization in coal-fired power plants. Its main component is calcium sulfate dihydrate, which can provide calcium and sulfate ions in alkaline activation systems, promoting the formation of ettringite and C-(A)-SH gels, thus enhancing the system and synergistically stabilizing it with sulfate. Currently, existing technologies mostly focus on highly active precursor systems such as slag and fly ash. For the mechanical activation of low-activity manganese tailings and the synergistic modification of alkaline-activated polymers with desulfurized gypsum, a systematic approach to formulation optimization, preparation processes, and solidification mechanisms has not yet been established, limiting the large-scale synergistic utilization of both manganese tailings and desulfurized gypsum as solid wastes.

[0005] Based on this, the present invention provides a desulfurized gypsum-modified alkali-activated manganese tailings-based polymer, which enhances the reactivity of manganese tailings through mechanical activation and optimizes the hydration products and microstructure through desulfurized gypsum, thereby achieving high-value utilization of solid waste and efficient solidification of sulfate ions. Summary of the Invention

[0006] To address the problems of low alkali activation activity, high sulfate leaching risk, and low solid waste utilization rate in existing technologies for manganese tailings, this application provides a desulfurized gypsum-modified alkali-activated manganese tailings-based polymer, its preparation method, and its application.

[0007] In a first aspect, this application provides a desulfurized gypsum-modified alkali-activated manganese tailings-based polymer, employing the following technical solution: the desulfurized gypsum-modified alkali-activated manganese tailings-based polymer is composed of a solid phase component and an alkali activator, wherein the liquid-to-solid ratio of the alkali activator to the solid phase component is 47.5–52.5% by mass; the solid phase component includes 90–98 wt% activated manganese tailings and 2–10 wt% desulfurized gypsum; in the alkali activator, the alkali content, calculated as sodium oxide equivalent, is 6–10 wt% of the solid phase component mass, and the alkali activator includes water glass, sodium hydroxide, and deionized water, wherein the water glass modulus is 1.2–1.8, and the manganese tailings are activated by ball milling, reducing the particle size D90 from 1026 μm to 52.864 μm.

[0008] By adopting the above technical solution, manganese tailings are ball-milled and activated at specific speeds and times, resulting in significantly finer particles and a significantly increased specific surface area. At the same time, lattice distortion and surface defects are induced, which greatly improves the alkaline activation reactivity of manganese tailings. This solves the problems of poor reactivity and low hydration degree of primary manganese tailings, and provides an active basis for the subsequent formation of dense hydration products. Furthermore, a gelling and solidification material is constructed with mechanically activated manganese tailings as the matrix, desulfurized gypsum as the modifying component, and a composite alkaline activator as the activation system. In this system, the solid phase component is measured at 100 wt% of the total solid phase mass, with activated manganese tailings accounting for 90–98 wt% and desulfurized gypsum accounting for 2–10 wt%. This ensures high utilization of the bulk solid waste, manganese tailings, while also introducing sulfate ions through a small amount of desulfurized gypsum to participate in the hydration reaction, achieving synergistic utilization of the two types of solid waste. The liquid-to-solid ratio is limited to 47.5–52.5%, with the amount of alkali activator calculated based on the total mass of the solid phase component. This ensures the slurry has suitable fluidity and molding properties, avoiding uneven mixing due to an excessively low liquid-to-solid ratio or a loose structure due to an excessively high ratio. The alkali dosage is set at 6–10 wt% of the solid phase component mass, with the total amount of alkali activation system determined based on the total mass of the solid phase. This provides a sufficient and stable alkalinity environment to ensure the continuous and thorough alkali activation reaction. The water glass modulus is controlled within the range of 1.2–1.8, achieved by adjusting the ratio of sodium hydroxide to water glass, to optimize the matching of system alkalinity, silicate concentration, and reaction rate. By designing the component ratio based on the total mass of the solid phase as the unified measurement standard, the high-value utilization of solid waste and the alkaline activation reaction are precisely matched, ensuring that the system has suitable slurry workability and sufficient driving force for hydration reaction, providing basic compositional conditions for the formation of stable hydration products and the reduction of sulfate leaching.

[0009] Preferably, the main chemical components of the manganese tailings, by mass fraction, are: SiO2 35.51%, SO3 20.85%, Al2O3 12.54%, CaO 9.82%, Fe2O3 8.74%, and MnO 3.62%.

[0010] Preferably, the main chemical components of the desulfurized gypsum are as follows by mass fraction: CaO 43.01%, SO3 52.36%, SiO2 1.99%, and Al2O3 1.21%.

[0011] Preferably, the raw materials used for the alkali activator are industrial-grade water glass with an initial modulus of 2.0 and analytical-grade sodium hydroxide, which are then mixed with deionized water to obtain an alkali activator with the target modulus.

[0012] Secondly, this application provides a method for preparing alkali-activated manganese tailings-based polymer modified with desulfurized gypsum, using the following technical solution: A method for preparing alkali-activated manganese tailings-based polymer modified with desulfurized gypsum includes the following steps: S1. Manganese tailings were ball-milled and activated for 12 minutes in a planetary ball mill at a ball-to-material ratio of 5:1, a mass ratio of Φ10mm to Φ6mm zirconia balls of 1:1, a filling rate of 50%, and a speed of 300r / min. The particle size D90 was reduced from 1026μm to 52.864μm, and the specific surface area was ≥800m² / kg. S2. At room temperature (20-25℃), first dissolve sodium hydroxide in deionized water, then add water glass, stir magnetically for 30 minutes to mix evenly, adjust to a modulus of 1.2-1.8, prepare an alkaline activator and age for 24 hours. S3. Add activated manganese tailings and desulfurized gypsum to a planetary mixer and dry mix at 1400 r / min for 60 s until uniform. Add aged alkali activator at a liquid-to-solid ratio of 47.5-52.5% by mass and wet mix at 1400 r / min for 120 s to form a uniform slurry. The slurry fluidity is controlled at 180±20 mm. S4. Pour the obtained slurry into a standard test mold, place it on a 50Hz concrete vibrating table with an amplitude of 1mm and vibrate for 45s, and then pour it into shape; let it stand at 25℃ for 24 hours before demolding; move it into a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% for curing for 3d, 7d, and 28d.

[0013] By adopting the above technical solution, a complete and controllable process is employed, including raw material activation, alkali aging, dry powder premixing, slurry mixing, vibration molding, and standard curing. In S1, the manganese tailings are ball-milled and activated at 300 r / min for 12 min. Mechanical grinding achieves particle refinement and lattice distortion, reducing the particle size D90 from 1026 μm to 52.864 μm. This significantly increases the specific surface area and surface defects, greatly enhancing the alkali-activated reactivity of the manganese tailings and providing high activity for subsequent full hydration. Raw material basis; In S2, at room temperature of 20-25℃, industrial water glass with an initial modulus of 2.0 and a Baume degree of 40Be′ is used as a reference, mixed with sodium hydroxide and deionized water and stirred until the modulus is 1.2-1.8. Then it is left to stand and age for 24 hours to ensure that the components of the alkali activator are fully miscible, the system is uniform and stable, eliminates component concentration gradients and reaction heat fluctuations, and avoids problems such as uneven alkalinity and excessive local reaction caused by on-site preparation; In S3, activated manganese tailings and desulfurized gypsum are first added to the process. The star-shaped mixer is used for dry mixing to ensure uniform dispersion of the solid components. Then, aged alkali activator is added at a liquid-to-solid ratio of 47.5–52.5% and an alkali content of 6–10%. The mixture is then thoroughly stirred to form a homogeneous slurry. This dry-then-wet mixing method prevents powder agglomeration and ensures sufficient contact between the solid and liquid phases, improving the homogeneity and stability of the slurry. In step S4, the homogeneous slurry is poured into a test mold and vibrated on a concrete vibrating table for 45 seconds to effectively expel air trapped inside the slurry and reduce internal porosity. The compaction process improves the initial density of the preform, providing a structural basis for the later formation of a low-porosity, high-strength cured body. After vibration, the preform is demolded after standing at 25℃ for 24 hours. Then, the preform is cured in a standard curing environment with a temperature of 20±2℃ and a relative humidity of ≥95% for 3 days, 7 days, and 28 days. This provides stable temperature and humidity conditions for the hydration reaction, ensuring the continuous formation of C-(A)-SH gel and ettringite, and the continuous compaction of the structure. Ultimately, this results in stable performance of the cured body and excellent sulfate curing effect.

[0014] Preferably, in step 4, the hydration products of the curing stage are mainly C-(A)-SH gel and ettringite.

[0015] Thirdly, this application provides the application of desulfurized gypsum-modified alkali-activated manganese tailings-based polymers, employing the following technical solution: Application of desulfurized gypsum-modified alkali-activated manganese tailings-based polymer: The desulfurized gypsum-modified alkali-activated manganese tailings-based polymer is used in sulfate ion solidification, mine backfilling, roadbed materials, and building cementitious materials.

[0016] By adopting the above technical solution, the polymer material has the advantages of high solid waste utilization rate, good sulfate solidification effect, dense and durable structure, and simple preparation process. It is highly compatible with mine filling, roadbed reinforcement, building cementation and pollution ion stabilization scenarios, and can realize the large-scale synergistic utilization of manganese tailings and desulfurized gypsum, which has both economic value and environmental benefits.

[0017] In summary, this application has the following beneficial effects: 1. This application utilizes ball milling of manganese tailings and the addition of an alkali activator to enable the resource utilization of both manganese tailings and desulfurization gypsum, two types of industrial solid waste. While processing large quantities of stockpiled waste manganese tailings, it can simultaneously consume industrial by-product desulfurization gypsum, thereby reducing the land occupation caused by open-air stockpiling of solid waste and the environmental pollution risks of water, soil, and dust caused by stockpiling of tailings and desulfurization gypsum. This solves the problems of low alkali activation activity of manganese tailings, high risk of sulfate leaching, and low utilization rate of solid waste in existing technologies.

[0018] 2. This application demonstrates that the curing system undergoes a continuous hydration reaction as the curing age increases. The hydration products, C-A-S-H and N-A-S-H gels, are continuously generated and fill the internal pores of the matrix, gradually making the sample structure more compact. The optimal ratio sample can achieve a compressive strength of 19.2 MPa after 28 days of curing. This results in a dense overall structure of the cured matrix with fewer defects, and the finished product has stable and reliable mechanical strength, thus meeting the requirements for use in tailings landfill, roadbed filling, and other projects.

[0019] 3. This application utilizes desulfurized gypsum to provide a sufficient calcium source for the system. Under alkaline activation conditions, it hydrates with aluminosilicate components to form ettringite. Through the dual effects of lattice encapsulation and physical coating, sulfate ions are stably fixed in the skeleton of the hydration products, resulting in a significant reduction in the sulfate leaching concentration to 415 mg / L after 28 days. This greatly reduces the risk of soil and groundwater pollution caused by sulfate leaching with leachate, and achieves the harmless and stable disposal of sulfate in tailings.

[0020] 4. All preparation processes in this application can be completed and cured at room temperature. The raw material processing is simple, the pretreatment process is short, the investment in production equipment is small and the operation is easy. Moreover, the production conditions are mild and controllable, and it can be directly implemented in existing solid waste disposal and building material processing production lines, which helps to facilitate continuous, large-scale industrial production.

[0021] 5. This application uses manganese tailings and desulfurized gypsum as the main raw materials, which can largely replace traditional silicate cement and significantly reduce the consumption of natural mineral resources such as limestone and clay. It also eliminates the high-temperature calcination process of cement clinker, thereby reducing the large amount of CO2 emissions during the clinker production process and lowering the carbon emissions throughout the product's life cycle. At the same time, it can recycle and dispose of existing stockpiled solid waste, reducing the land occupied by solid waste landfill and the ecological pollution caused by solid waste stockpiling, thus achieving the effects of low-carbon environmental protection and solid waste recycling. Attached Figure Description

[0022] Figure 1 This is a flowchart of the preparation method of desulfurized gypsum modified alkali-activated manganese tailings-based polymer provided in this application; Figure 2 This is a schematic diagram illustrating the particle size distribution and activation mechanism of manganese tailings at different ball milling times in this application; Figure 3 These are test diagrams of compressive strength at different maintenance ages in this application; Figure 4 These are SEM-EDS and MIP pore structure analysis diagrams at different ages in this application; Figure 5 This is a schematic diagram of sulfate leaching concentration at different ages in this application. Detailed Implementation

[0023] The present application will be further described in detail below with reference to embodiments and comparative examples. Unless otherwise specified, the experimental methods used below are conventional methods. Unless otherwise specified, the materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art, which can be obtained by those skilled in the art through commercial channels or prepared according to literature methods.

[0024] Technical concept: Existing alkali-activated manganese tailings polymers still face significant technical bottlenecks in the co-utilization of solid waste and sulfate stabilization treatment. On the one hand, manganese tailings themselves have low activity, and simple mechanical grinding cannot achieve a synergistic improvement in particle size and reactivity, resulting in insufficient hydration and a loose structure. On the other hand, sulfate ions introduced by desulfurization gypsum are prone to continuous leaching in an aqueous environment, causing secondary pollution. Conventional solidification methods rely solely on physical encapsulation, resulting in poor long-term stability and difficulty in meeting environmental durability requirements. Furthermore, traditional alkali-activated systems often employ on-site preparation of alkali solutions and direct mixing for molding, leading to uneven component mixing, large fluctuations in system stability, unclear curing conditions, and poor controllability of microstructure. This results in high porosity and insufficient density, making it difficult to simultaneously achieve sulfate solidification efficiency and structural integrity.

[0025] To address the problems of low activity of manganese tailings, high risk of sulfate leaching, unclear hydration products, loose microstructure, and uncontrollable preparation process in the existing technologies, this invention constructs an integrated technical solution of desulfurized gypsum synergistic modification + mechanical activation and revitalization + alkali activator aging and stabilization + standard curing and densification. By precisely ball-milling and activating manganese tailings, significant particle refinement and lattice distortion are achieved, greatly enhancing its alkali-activated reaction activity. Using desulfurized gypsum as an internal modifier, C-(A)-SH gel and ettringite composite hydration products are directionally generated under the activation system. Relying on the product's own expansibility to fill pores and optimize the microstructure, the total porosity is significantly reduced and the structure is densified. A composite alkali activator with aging pretreatment is used to ensure uniform and stable alkalinity of the system, avoiding structural defects caused by excessively high local alkalinity. Combined with standardized mixing, vibration molding, and standard temperature and humidity curing, the slurry is made uniform and dense, and hydration is fully carried out. Ultimately, while ensuring high utilization of solid waste, sulfate ions are stably solidified in the lattice and matrix structure of the hydration products, significantly reducing the sulfate leaching concentration and improving the long-term environmental safety and structural stability of the material.

[0026] The following are the main raw materials and reagents used in the examples and comparative examples, and their sources and specifications are as follows; unless otherwise specified, all reagents are commercially available analytical grade or higher products: 1. The manganese tailings are tailings from the beneficiation of manganese oxide ore. The main chemical components, by mass fraction, are: SiO2 35.51%, SO3 20.85%, Al2O3 12.54%, CaO 9.82%, Fe2O3 8.74%, MnO 3.62%; 2. Desulfurized gypsum: The main chemical components of industrial by-product desulfurized gypsum, by mass fraction, are: CaO 43.01%, SO3 52.36%, SiO2 1.99%, Al2O3 1.21%; 3. The water glass is industrial grade, the alkali activator is industrial grade water glass with a modulus of 2.0 and a Baumé degree of 40±1 Bé, and it is analytical grade sodium hydroxide; wherein, the liquid-solid ratio = total mass of alkali activator / total mass of solid phase; the alkali content, expressed as Na2O equivalent, is 6% to 10% of the mass of solid phase component; and in this application, the water glass is divided into the initial modulus of raw material and the modulus after preparation, which are different concepts; 4. The sodium hydroxide is industrial grade, with NaOH ≥ 96%.

[0027] Example 1: This application provides a desulfurized gypsum-modified alkali-activated manganese tailings-based polymer, which consists of a solid phase component and an alkali activator. By mass ratio, the liquid-solid ratio of the alkali activator to the solid phase component is 50%. The solid phase component includes 94 wt% activated manganese tailings and 6 wt% desulfurized gypsum. In the alkali activator, the alkali content, calculated as sodium oxide equivalent, is 8 wt% of the solid phase component mass. The alkali activator includes water glass, sodium hydroxide, and deionized water. The water glass modulus is 1.5. The manganese tailings are activated by ball milling, and the particle size D90 is reduced from 1026 μm to 52.864 μm. The main chemical components of manganese tailings by mass fraction are: SiO2 35.51%, SO3 20.85%, Al2O3 12.54%, CaO 9.82%, Fe2O3 8.74%, MnO 3.62%; The main chemical components of desulfurized gypsum, by mass fraction, are: CaO 43.01%, SO3 52.36%, SiO2 1.99%, and Al2O3 1.21%. The raw materials used for the alkali activator are industrial-grade water glass with an initial modulus of 2.0 and analytical grade sodium hydroxide, which are then mixed with deionized water to obtain the alkali activator with the target modulus. A method for preparing alkali-activated manganese tailings-based polymer modified with desulfurized gypsum includes the following steps: S1. Manganese tailings were ball-milled and activated for 12 minutes in a planetary ball mill at a ball-to-material ratio of 5:1, a mass ratio of Φ10mm to Φ6mm zirconia balls of 1:1, a filling rate of 50%, and a speed of 300r / min. The particle size D90 was reduced from 1026μm to 52.864μm, and the specific surface area was ≥800m² / kg. S2. At room temperature (20-25℃), first dissolve sodium hydroxide in deionized water, then add water glass, stir magnetically for 30 minutes to mix evenly, adjust to a modulus of 1.5, prepare an alkali activator and age for 24 hours. S3. Add activated manganese tailings and desulfurized gypsum to a planetary mixer and dry mix at 1400 r / min for 60 s until uniform. Add aged alkali activator at a liquid-solid ratio of 50% by mass and wet mix at 1400 r / min for 120 s to form a uniform slurry. The slurry fluidity is controlled at 180 ± 20 mm. S4. Pour the obtained slurry into a standard test mold, place it on a 50Hz concrete vibrating table with an amplitude of 1mm and vibrate for 45s, and then pour it into shape; let it stand at 25℃ for 24 hours to demold; move it into a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% for 3d, 7d, and 28d respectively. The hydration products during the curing stage are mainly C-(A)-SH gel and ettringite.

[0028] Example 2: This application provides a desulfurized gypsum-modified alkali-activated manganese tailings-based polymer, which consists of a solid phase component and an alkali activator. By mass ratio, the liquid-solid ratio of the alkali activator to the solid phase component is 47.5%. The solid phase component includes 98 wt% activated manganese tailings and 2 wt% desulfurized gypsum. In the alkali activator, the alkali content, calculated as sodium oxide equivalent, is 6 wt% of the mass of the solid phase component. The alkali activator includes water glass, sodium hydroxide, and deionized water. The water glass modulus is 1.2. The manganese tailings are activated by ball milling, and the particle size D90 is reduced from 1026 μm to 52.864 μm. The main chemical components of manganese tailings by mass fraction are: SiO2 35.51%, SO3 20.85%, Al2O3 12.54%, CaO 9.82%, Fe2O3 8.74%, MnO 3.62%; The main chemical components of desulfurized gypsum, by mass fraction, are: CaO 43.01%, SO3 52.36%, SiO2 1.99%, and Al2O3 1.21%. The raw materials used for the alkali activator are industrial-grade water glass with an initial modulus of 2.0 and analytical grade sodium hydroxide, which are then mixed with deionized water to obtain the alkali activator with the target modulus. A method for preparing alkali-activated manganese tailings-based polymer modified with desulfurized gypsum includes the following steps: S1. Manganese tailings were ball-milled and activated for 12 minutes in a planetary ball mill at a ball-to-material ratio of 5:1, a mass ratio of Φ10mm to Φ6mm zirconia balls of 1:1, a filling rate of 50%, and a speed of 300r / min. The particle size D90 was reduced from 1026μm to 52.864μm, and the specific surface area was ≥800m² / kg. S2. At room temperature (20-25℃), first dissolve sodium hydroxide in deionized water, then add water glass, stir magnetically for 30 minutes to mix evenly, adjust to a modulus of 1.2, prepare an alkaline activator and age for 24 hours. S3. Add activated manganese tailings and desulfurized gypsum to a planetary mixer and dry mix at 1400 r / min for 60 s until uniform. Add aged alkali activator at a liquid-to-solid ratio of 47.5% by mass and wet mix at 1400 r / min for 120 s to form a uniform slurry. The slurry fluidity is controlled at 180 ± 20 mm. S4. Pour the obtained slurry into a standard test mold, place it on a 50Hz concrete vibrating table with an amplitude of 1mm and vibrate for 45s, and then pour it into shape; let it stand at 25℃ for 24 hours to demold; move it into a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% for 3d, 7d, and 28d respectively. The hydration products during the curing stage are mainly C-(A)-SH gel and ettringite.

[0029] Example 3: This application provides a desulfurized gypsum-modified alkali-activated manganese tailings-based polymer, which consists of a solid component and an alkali activator. The liquid-solid ratio of the alkali activator to the solid component is 52.5% by mass. The solid component includes 90 wt% activated manganese tailings and 10 wt% desulfurized gypsum. In the alkali activator, the alkali content, calculated as sodium oxide equivalent, is 10 wt% of the mass of the solid component. The alkali activator includes water glass, sodium hydroxide, and deionized water. The water glass modulus is 1.8. The manganese tailings are activated by ball milling, and the particle size D90 is reduced from 1026 μm to 52.864 μm. The main chemical components of manganese tailings by mass fraction are: SiO2 35.51%, SO3 20.85%, Al2O3 12.54%, CaO 9.82%, Fe2O3 8.74%, MnO 3.62%; The main chemical components of desulfurized gypsum, by mass fraction, are: CaO 43.01%, SO3 52.36%, SiO2 1.99%, and Al2O3 1.21%. The raw materials used for the alkali activator are industrial-grade water glass with an initial modulus of 2.0 and analytical grade sodium hydroxide, which are then mixed with deionized water to obtain the alkali activator with the target modulus. A method for preparing alkali-activated manganese tailings-based polymer modified with desulfurized gypsum includes the following steps: S1. Manganese tailings were ball-milled and activated for 12 minutes in a planetary ball mill at a ball-to-material ratio of 5:1, a mass ratio of Φ10mm to Φ6mm zirconia balls of 1:1, a filling rate of 50%, and a speed of 300r / min. The particle size D90 was reduced from 1026μm to 52.864μm, and the specific surface area was ≥800m² / kg. S2. At room temperature (20-25℃), first dissolve sodium hydroxide in deionized water, then add water glass, stir magnetically for 30 minutes to mix evenly, adjust to a modulus of 1.8, prepare an alkali activator and age for 24 hours. S3. Add activated manganese tailings and desulfurized gypsum to a planetary mixer and dry mix at 1400 r / min for 60 s until uniform. Add aged alkali activator at a liquid-to-solid ratio of 52.5% by mass and wet mix at 1400 r / min for 120 s to form a uniform slurry. The slurry fluidity is controlled at 180 ± 20 mm. S4. Pour the obtained slurry into a standard test mold, place it on a 50Hz concrete vibrating table with an amplitude of 1mm and vibrate for 45s, and then pour it into shape; let it stand at 25℃ for 24 hours to demold; move it into a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% for 3d, 7d, and 28d respectively. The hydration products during the curing stage are mainly C-(A)-SH gel and ettringite.

[0030] Comparative Example 1: The only difference between this comparative example and Example 1 is that the manganese tailings are not ball-milled; the other raw material components, proportions and preparation processes are the same as in Example 1.

[0031] Comparative Example 2: The only difference between this comparative example and Example 1 is that no desulfurized gypsum is added; the other raw material components, proportions and preparation processes are the same as in Example 1.

[0032] Experiment 1: Performance Comparison Experiment of Alkali-Activated Manganese Tailings-Based Polymer Modified by Desulfurized Gypsum The compressive strength was determined according to GB / T17671-2021, with specimen dimensions of 40mm×40mm×40mm and a loading rate of 2.4kN / s. The sulfate leaching concentration was determined according to HJ / T299-2007 sulfuric acid-nitric acid method, with an extraction liquid-to-solid ratio of 10:1, and the sample was shaken at 23±2℃ and 110±10r / min for 8h. Ion chromatography was used for detection. The pore structure and micromorphology were determined by MIP testing, with pore sizes ranging from 3nm to 300μm. The SEM samples were crushed, vacuum dried, and carbon-sprayed, with an accelerating voltage of 20kV. XRD was performed using a Cu target with a scanning range of 10° to 80° to confirm the presence of ettringite and C-(A)-SH gel. This experiment involved preparing slurries according to the specified proportions for all samples in the examples and comparative examples. The slurries were poured into 40mm×40mm×40mm molds, vibrated to remove bubbles, and then allowed to stand at 25℃ for 24 hours before demolding. The samples were then cured at room temperature for 28 days. Parallel samples were taken for performance testing. The 28-day compressive strength was tested using a pressure testing machine. Leaching experiments were conducted according to the HJ / T299 method, and the sulfate leaching concentration was determined using ion chromatography. The sulfate solidification rate was calculated using the formula. The microstructure was observed using a scanning electron microscope (SEM). Curing conditions, sample appearance, and test data stability were recorded simultaneously. The experimental results are shown in Table 1.

[0033] Table 1: Experiment 2: Orthogonal Experiment for Optimized Formulation of Alkali-Activated Manganese Tailings-Based Polymer Modified by Desulfurized Gypsum Based on the single-factor experiments, an orthogonal experiment was designed. A four-factor, three-level design was adopted to optimize the preparation method of desulfurized gypsum-modified alkali-activated manganese tailings-based polymer. The desulfurized gypsum content (A), water glass modulus (B), alkali equivalent (C), and solid-liquid ratio (D) were investigated. The compressive strength at room temperature curing ages of 3d, 7d, and 28d and the sulfate leaching concentration of the horizontal sample were used as indicators to analyze the interrelationships between the three levels of the four factors, optimize the extraction conditions, and select the L9 (34) orthogonal array to arrange the orthogonal experiment of the preparation method of desulfurized gypsum-modified alkali-activated manganese tailings-based polymer. The design scheme is shown in Table 2. Table 2: Table 2 continued: The results of the orthogonal test compressive strength are shown in Table 3.

[0034] Table 3: The sulfate leaching concentration of the original manganese tailings in the orthogonal experiment is as follows: Figure 5 The result shown is 6652 mg / L; the results for parallel samples at 3d, 7d, and 28d are shown in Table 4.

[0035] Table 4: In summary, based on the compressive strength, sulfate leaching concentration, and other parameters of the samples in Tables 2-4 of the orthogonal experiment, the results indicate that... Figure 3 - Figure 5 The comprehensive comparison of the test results shows that the DG-9-3 formulation with the following proportions—6% desulfurized gypsum, 1.5 water glass modulus, 8% alkali equivalent, and 50% liquid-solid ratio—resulted in the highest 28-day compressive strength of the cured sample, and the lowest sulfate leaching concentration and total matrix porosity among all orthogonal samples. Compared to the low gypsum content group (2%), which had insufficient calcium source, poor sulfur fixation effect, and low strength, and the high gypsum content group (10%), which had high sulfate dissolution due to the introduction of free sulfur from the excess desulfurized gypsum, this optimal formulation can fully ensure the continuous formation of hydration gel and ettringite, while taking into account both mechanical properties and sulfate curing stability. Therefore, DG-9-3 is the optimal formulation for this experiment.

[0036] Combining Examples 1-3 and Comparative Example 1 with Table 1, it can be seen that, under the conditions of 6wt% desulfurized gypsum addition, water glass modulus 1.5, 8wt% alkali content, 50% liquid-to-solid ratio, and ball milling of tailings, Example 1 achieved the best performance among all groups in terms of three indicators: 28-day compressive strength of the cured sample reached 19.2 MPa, sulfate leaching concentration was only 415 mg / L, and total porosity was 9.81%. Example 2, with a low desulfurized gypsum content (2wt%), had insufficient calcium source supply and low hydration gel formation, resulting in a sample compressive strength of 10.8 MPa and simultaneous sulfate leaching and porosity reduction. The concentrations of sulfate leaching in Example 1 increased to 442 mg / L and 18.54%. Example 3, with a high concentration of desulfurized gypsum (10 wt%), had an excessive amount of desulfurized gypsum, which introduced free sulfate, resulting in a sulfate leaching concentration of 428 mg / L. Simultaneously, the excess components compromised the matrix density, leading to lower strength and porosity performance compared to Example 1. Comparative Example 1 had the same formulation parameters as Example 1, but the manganese tailings were not ball-milled for activation, resulting in insufficient mineral activity and incomplete hydration. The compressive strength was only 8.7 MPa, and the sulfate leaching concentration soared to 2064 mg / L with a total porosity of 24.92%, significantly worse than Example 1. These data collectively demonstrate that the raw material ratio and tailings ball-milling process in Example 1 were the optimal solution for this experiment.

[0037] Therefore, to improve the efficiency of manganese tailings reaction and to standardize the ball milling process, please refer to... Figure 2 ,Depend on Figure 2 The particle size test results of the four groups (a) to (d) show that the median particle size of the un-ball-milled manganese tailings (corresponding to Figure a) is D50=243.536μm and D90=1026.065μm. The volume ratio of coarse particles (400-2000μm range) is as high as 30.767%. The mineral particles are large and have small specific surface area. The aluminosilicate minerals are difficult to be eroded by the alkali activator and have extremely poor reactivity. As the ball milling time is gradually extended, the manganese tailings particles are continuously refined, the proportion of coarse particle components is continuously reduced, and the proportion of fine particles is gradually increased. When the ball milling time is optimized to 12min as specified in this invention (Figure d), the D50 of the manganese tailings drops to 6.231μm and the D90 drops to 52.864μm. The cumulative proportion of fine particles of 0.5-10μm reaches 60.352%, and the large-particle tailings in the raw material are basically eliminated. Based on the mechanical activation mechanism shown in Figure (e), the ball milling process can break the Si-O chemical bonds on the mineral surface and expose a large number of active sites, thereby improving the alkali-activated reaction activity of manganese tailings from both macroscopic particle size and microscopic chemical bond perspectives. The above particle size evolution data fully demonstrates that the 12-minute ball milling process parameter selected in this application is supported by sufficient experimental data, which can achieve efficient activation of manganese tailings while avoiding the energy redundancy caused by excessive ball milling. The selection of process parameters is scientific and reasonable.

[0038] In conjunction with Examples 1-3 and Comparative Example 2, and in conjunction with Table 1 and Figure 4 It can be seen that Comparative Example 2 has no desulfurized gypsum, corresponding to Figure 4 a, b: a is a low-magnification SEM image showing a loose and porous matrix; b is a high-magnification image showing a large number of elongated free CaSO4 crystals, indicating a lack of sufficient calcium to form ettringite and fix sulfate ions; c is a 3d pore size distribution curve, showing large pores and a high proportion of macropores in the early stage, corresponding to well-developed early porosity and easy sulfur leaching. In Table 1, the sulfate leaching of this group is as high as 6652 mg / L, the total porosity is 25.68%, and the compressive strength is only 12.0 MPa. In Example 2 (2% low gypsum) and Example 3 (10% excess gypsum), the calcium source was insufficient or the gypsum was excessive, resulting in insufficient hydration product formation, corresponding to... Figure 4 d, e: d shows a large amount of exposed quartz tailings particles; e shows less C-(A)-SH gel and more exposed tailings particles, with more matrix pores. Table 1 shows that the porosity and sulfate leaching of both are higher than in Example 1; f is the pore size curve over 7 days, which gradually refines with curing and hydration, but is still inferior to the optimal ratio. Example 1 is the optimal ratio, corresponding to... Figure 4g, h, i, j, k: g shows a dense matrix at low magnification; h shows tailings particles completely encapsulated by C-(A)-SH gel and ettringite at high magnification; i is the 28-day pore size curve, showing a significant refinement of pore size and a substantial reduction in macropores, corresponding to a porosity of 9.81% in Table 1; j shows uniform dispersion of Ca, Si, Al, and S elements in elemental surface scanning; k shows that the Ca and S element ratio matches the formation of ettringite, and sulfate ions are fixed within the hydration products. Table 1 shows a 28-day compressive strength of 19.2 MPa and a sulfate leaching of only 415 mg / L. From the changes in the three MIP curves c(3d)→f(7d)→i(28d), it can be seen that the optimal sample undergoes continuous hydration with prolonged curing age, resulting in a continuous refinement of pore size and a gradual densification of the matrix. Based on the comprehensive analysis of macroscopic properties, microscopic morphology, pore size evolution, and elemental analysis results, it was confirmed that a 6 wt% desulfurization gypsum content can effectively promote the formation of hydration products, optimize pore structure, and stabilize and solidify sulfate ions, making it the optimal formulation for this experiment.

[0039] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A desulfurized gypsum-modified alkali-activated manganese tailings-based polymer, characterized in that, Composed of a solid phase component and an alkali activator, the liquid-to-solid ratio of the alkali activator to the solid phase component is 47.5–52.5% by mass. The solid phase component includes 90–98 wt% activated manganese tailings and 2–10 wt% desulfurized gypsum. The alkali activator, in sodium oxide equivalent, has an alkali content of 6–10 wt% of the solid phase component mass and includes water glass, sodium hydroxide, and deionized water. The water glass modulus is 1.2–1.

8. The manganese tailings are activated by ball milling, reducing the particle size D90 from 1026 μm to 52.864 μm.

2. The desulfurized gypsum-modified alkali-activated manganese tailings-based polymer according to claim 1, characterized in that: The main chemical components of the manganese tailings, by mass fraction, are: SiO2 35.51%, SO3 20.85%, Al2O3 12.54%, CaO 9.82%, Fe2O3 8.74%, and MnO 3.62%.

3. The desulfurized gypsum-modified alkali-activated manganese tailings-based polymer according to claim 1, characterized in that: The main chemical components of the desulfurized gypsum, by mass fraction, are: CaO 43.01%, SO3 52.36%, SiO2 1.99%, and Al2O3 1.21%.

4. The desulfurized gypsum-modified alkali-activated manganese tailings-based polymer according to claim 1, characterized in that: The raw materials used for the alkali activator are industrial-grade water glass with an initial modulus of 2.0 and analytical-grade sodium hydroxide, which are then mixed with deionized water to obtain an alkali activator with the target modulus.

5. A method for preparing alkali-activated manganese tailings-based polymer modified with desulfurized gypsum, characterized in that, The method for using the desulfurized gypsum-modified alkali-activated manganese tailings-based polymer according to any one of claims 1-4 comprises the following steps: S1. Manganese tailings were ball-milled and activated for 12 minutes in a planetary ball mill at a ball-to-material ratio of 5:1, a mass ratio of Φ10mm to Φ6mm zirconia balls of 1:1, a filling rate of 50%, and a speed of 300r / min. The particle size D90 was reduced from 1026μm to 52.864μm, and the specific surface area was ≥800m² / kg. S2. At room temperature (20-25℃), first dissolve sodium hydroxide in deionized water, then add water glass, stir magnetically for 30 minutes to mix evenly, adjust to a modulus of 1.2-1.8, prepare an alkaline activator and age for 24 hours. S3. Add activated manganese tailings and desulfurized gypsum to a planetary mixer and dry mix at 1400 r / min for 60 s until uniform. Add aged alkali activator at a liquid-to-solid ratio of 47.5-52.5% by mass and wet mix at 1400 r / min for 120 s to form a uniform slurry. The slurry fluidity is controlled at 180±20 mm. S4. Pour the obtained slurry into a standard test mold, place it on a 50Hz concrete vibrating table with an amplitude of 1mm and vibrate for 45s, and then pour it into shape; let it stand at 25℃ for 24 hours before demolding; move it into a standard curing room with a temperature of 20±2℃ and a relative humidity of ≥95% for curing for 3d, 7d, and 28d.

6. The method for preparing the desulfurized gypsum-modified alkali-activated manganese tailings-based polymer according to claim 5, characterized in that, In step 4, the hydration products during the curing stage are mainly C-(A)-SH gel and ettringite.

7. The application of desulfurized gypsum-modified alkali-activated manganese tailings-based polymers, characterized in that, The desulfurized gypsum-modified alkali-activated manganese tailings-based polymer according to any one of claims 1-4 is used in sulfate ion solidification, mine backfilling, roadbed materials and building cementitious materials.

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