A light-weight gel material for treating mine tailings and a method of making the same

Abstract

The application discloses a light gel material for treating mine tailings and a preparation method thereof, and relates to the technical field of light building materials. The method comprises the following steps: sequentially performing alkali etching activation, nano-silica coating and epoxy silane grafting modification on basalt fibers; and performing organic intercalation and amino silane grafting on sodium-based montmorillonite, and then performing double crosslinking on the sodium-based montmorillonite and sodium alginate to prepare an organic-inorganic composite modifier. The mine tailings, cement, fly ash and silica ash are dry-mixed, a liquid component containing polyethylene glycol and water glass is added to prepare a slurry, and then the modified fibers and the composite modifier are added and mixed and foamed, and then pouring, curing and maintenance are performed to obtain the light gel material. The light gel material is prepared by utilizing a multilayer interface reinforcement and interpenetrating network synergistic toughening mechanism, the mechanical strength of the tailings-based light gel material is effectively improved, and high-value utilization of mine solid wastes is realized.

Description

Technical Field

[0001] This invention relates to the field of lightweight building materials technology, specifically to a lightweight gel material for treating mine tailings and its preparation method. Background Technology

[0002] Tailings generated during mining and mineral processing are a mixture of fine-grained solid waste and water remaining after mineral processing. Their complex composition often contains residual mineral processing reagents and various heavy metal ions, which, if not properly disposed of, will cause continuous pollution to the surrounding soil and groundwater environment. Currently, tailings disposal still primarily relies on tailings dam storage, but this method suffers from problems such as large land occupation, high risk of dam failure, and difficulty in ecological restoration. Using solidification / stabilization technology to process tailings into lightweight construction materials with a certain load-bearing capacity for mine backfilling or ecological restoration is an effective way to achieve tailings reduction, harmlessness, and resource utilization. Among various solidification solutions, lightweight gel materials show promising application prospects in tailings solidification treatment due to their advantages such as light weight, good fluidity, pumpability, and flexible preparation processes. However, the foam pore structure necessary for lightweighting, while reducing the material's bulk density, inevitably weakens its mechanical strength significantly, making it difficult to meet the basic load-bearing requirements of engineering scenarios such as mine backfilling, surcharges, and roadbeds. How to effectively improve the mechanical properties of gel lightweight building materials while maintaining their lightweight characteristics is a key technical bottleneck restricting the promotion and application of such materials. Summary of the Invention

[0003] The purpose of this invention is to provide a lightweight gel material for treating mine tailings and its preparation method, so as to solve the technical problems mentioned in the background.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a lightweight gel material for treating mine tailings includes the following steps: 1) Short-cut basalt fibers were alkali-etched and activated with sodium hydroxide solution, washed with water until neutral, and then dried to obtain alkali-etched basalt fibers; 2) A silica sol was prepared by using tetraethyl orthosilicate, anhydrous ethanol, deionized water and hydrochloric acid. The alkaline-etched basalt fibers were subjected to repeated impregnation-drying cycles and then heat treatment to obtain basalt fibers with a nano-silica coating on the surface. 3) Prepare a coupling agent hydrolysate by mixing γ-glycidyl etheroxypropyltrimethoxysilane, anhydrous ethanol, deionized water and glacial acetic acid. Immerse the fiber obtained in step 2) in the solution and react. After washing and curing, the modified basalt fiber is obtained. 4) Disperse sodium-based montmorillonite in deionized water and react it with hexadecyltrimethylammonium bromide via ion exchange. After washing, drying, grinding and sieving, organic intercalated montmorillonite powder is obtained. 5) Disperse organic intercalated montmorillonite powder in anhydrous toluene, add γ-aminopropyltriethoxysilane, heat under nitrogen protection and reflux reaction, and obtain silane-grafted montmorillonite after washing and vacuum drying; 6) Dissolve sodium alginate in deionized water, add silane-grafted montmorillonite for intercalation dispersion, add glutaraldehyde and calcium chloride solution in sequence for double cross-linking reaction, and obtain montmorillonite / sodium alginate composite modifier powder after freeze drying, grinding and sieving. 7) Mix the mine tailings, ordinary silicate cement, fly ash and silica fume evenly, add the liquid component consisting of polyethylene glycol, water glass and deionized water and stir to form a slurry. Then add modified basalt fiber and montmorillonite / sodium alginate composite modifier powder to the slurry and mix well. After adding foam, pour and mold it. After curing, the lightweight gel material is obtained.

[0005] In the technical solution of this invention, the mechanical strength of lightweight gel materials is improved in the following ways: (1) The mechanical strength of lightweight gel materials is improved by constructing a micro-reinforced skeleton network through multi-level surface engineering of basalt fibers. The mechanism is as follows: Alkali etching treatment forms a dense nanoscale pit and groove structure on the fiber surface, which transforms the originally smooth fiber surface into a high roughness morphology, greatly increasing the effective contact area and providing abundant physical anchoring points for the stable adhesion of subsequent functional coatings; The nano-silica transition coating constructed on the fiber surface further enhances the micro-mechanical interlocking effect with its high specific surface area and nanoporous morphology. At the same time, the transition coating, as an elastic modulus gradient buffer layer, effectively alleviates the interface stress mutation phenomenon caused by the stiffness difference between high modulus fibers and low modulus gel matrix; The outermost grafted epoxy silane coupling agent functional layer forms a strong interface bond with the gel matrix components through its active groups, establishing a continuous stress transmission channel between the fiber and the matrix. The roughened substrate, nano-coating transition, and chemical bonding interface design formed by the above three-layer structure enable the load to be efficiently transferred from the gel matrix to the three-dimensionally distributed fiber skeleton network through a stepwise transfer path, giving full play to the bridging and deflection effect of the fibers on microcracks, and significantly improving the compressive strength and flexural strength of the lightweight gel material. (2) The mechanical strength of the lightweight gel material is improved by constructing an organic-inorganic composite modification system with a hierarchical structure. The mechanism is as follows: the organic quaternary ammonium salt intercalation treatment effectively expands the spacing between the originally tightly stacked nanosheets of montmorillonite, creating the necessary spatial channels for the subsequent intercalation of macromolecular chain segments; the silane coupling agent introduces reactive anchoring sites in the expanded interlayer and sheet edge, enabling the inorganic sheets to have the bridging ability to directly covalently connect with the organic components; after the sodium alginate polymer chain enters the interlayer of montmorillonite, it forms an organic network by means of the dual curing mechanism of covalent cross-linking of glutaraldehyde and cross-linking of calcium ions, connecting the independent montmorillonite nanosheets into an integrated organic-inorganic interpenetrating network structure. After the composite structure is dispersed in the gel matrix, the high aspect ratio montmorillonite nanosheets form a rigid barrier at the microscopic level, which can effectively prevent the straight-line propagation of cracks, forcing the crack path to repeatedly deflect and bifurcate, thereby significantly increasing the consumption of fracture energy. Meanwhile, the flexible sodium alginate cross-linking network between the sheets can continuously absorb and dissipate mechanical energy through conformational deformation and chain segment slip under external force, avoiding excessive stress concentration at the rigid sheet interface. This achieves a synergistic improvement in both reinforcement and toughening properties, effectively compensating for the loss of mechanical load-bearing capacity in lightweight gel materials due to the introduction of high-porosity foam structures.

[0006] Preferably, in step 1), the concentration of the sodium hydroxide solution is 1-2 mol / L.

[0007] Preferably, in step 1), the alkaline etching activation treatment temperature is 70-80℃ and the time is 1-2h.

[0008] Preferably, in step 2), the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, and deionized water is (30-40):160:20.

[0009] Preferably, in step 3), the reaction temperature is 60-70°C and the reaction time is 2-3 hours.

[0010] Preferably, in step 4), the mass ratio of sodium montmorillonite to hexadecyltrimethylammonium bromide is 50:(18-22).

[0011] Preferably, in step 5), the mass ratio of the organic intercalated montmorillonite powder to γ-aminopropyltriethoxysilane is 40:(6-10).

[0012] Preferably, in step 6), the mass ratio of sodium alginate to silane-grafted montmorillonite is 10:(9-11).

[0013] Preferably, in step 6), the concentration of the calcium chloride solution is 0.1–0.2 mol / L.

[0014] Preferably, in step 7), the mass ratio of silica fume to polyethylene glycol is 15:(4-6).

[0015] This invention revealed in experiments that basalt fibers treated with multi-level surface engineering exhibit a hydrophobic overall characteristic, with their outermost layer being an organic functional layer formed by an epoxy silane coupling agent. In contrast, the sodium alginate crosslinking network in the montmorillonite / sodium alginate composite modifier is rich in hydroxyl and carboxyl groups, exhibiting a hydrophilic overall characteristic. The difference in surface properties between these two types of modifiers leads to the formation of microscale voids and weak bonding layers at their interface in the aqueous gel slurry system. These interface defects become stress concentration sources and crack initiation sites under mechanical loading, limiting the load transfer efficiency between the one-dimensional fiber network and the two-dimensional nanosheet network, preventing the optimal level of synergistic reinforcement between the two. To address this technical problem, this invention introduces two components: silica fume and polyethylene glycol 600. The ultrafine particle size of silica fume (average 0.1–0.3 μm) allows it to effectively fill the micro-voids at the interface between the fiber and the composite modifier particles, eliminating interfacial porosity defects through a physical filling effect. Simultaneously, silica fume exhibits high pozzolanic activity, enabling it to undergo a secondary hydration reaction with calcium hydroxide released during cement hydration, generating a dense hydrated calcium silicate cementitious phase at the interface and constructing a robust inorganic cementitious transition layer. Polyethylene glycol 600, as a low-molecular-weight flexible polyether polymer, has regularly arranged ether bonds on its polyether backbone that generate good affinity adsorption between the ether oxygen atoms and the organic coating on the fiber surface through van der Waals forces. Furthermore, its terminal hydroxyl groups and ether oxygen atoms can form hydrogen bonds with the hydrophilic hydroxyl and carboxyl groups on the surface of the composite modifier, providing molecular-level flexible bridging and wetting compatibility at the heterogeneous interface between the fiber and the composite modifier. The rigid filling-chemical bonding mechanism of silica fume and the flexible bridging-compatibility mechanism of polyethylene glycol work synergistically to construct a continuous, dense interface structure with rigid-flexible gradient transition characteristics at the interface between the one-dimensional fiber-reinforced network and the two-dimensional nanosheet-toughened network. This eliminates micropores and stress concentration defects, enabling defect-free coupling and transfer of loads between the fibers and nanosheets, thus maximizing the synergistic reinforcement effect of both aspects.

[0016] A lightweight gel material for treating mine tailings is prepared by the method described above.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. By sequentially subjecting basalt fibers to alkaline etching for roughening, a nano-silica coating transition, and epoxy-based silane coupling agent grafting treatment, a three-layer interface structure was constructed on the fiber surface, transitioning from physical anchoring and modulus to chemical bonding. This design achieves efficient load transfer from the matrix to the fiber skeleton, fully leveraging the bridging and deflection effect of the fibers on microcracks, and significantly improving the compressive and flexural strength of the material.

[0018] 2. An organic-inorganic interpenetrating structure was constructed through organic intercalation, silane grafting, and double crosslinking treatment. This structure utilizes rigid montmorillonite nanosheets to inhibit crack propagation and a flexible sodium alginate network to dissipate mechanical energy. This structure effectively compensates for the mechanical losses caused by the high porosity of lightweight materials by employing a synergistic mechanism of rigid crack resistance and flexible energy dissipation, thus improving both strength and toughness.

[0019] 3. Ultrafine silica fume is introduced to physically fill the micropores between the fibers and the composite modifier, generating dense hydration products to form a rigid bond. Simultaneously, the flexible segments of polyethylene glycol are utilized to create hydrogen bond bridging and wetting compatibility at the heterogeneous interface. This synergistic effect of rigidity and flexibility eliminates interfacial stress concentration defects, ensuring defect-free coupling and force transfer between the one-dimensional fiber skeleton and the two-dimensional nanosheet network, thus optimizing the synergistic reinforcement effect of the system. Attached Figure Description

[0020] Figure 1 This is a low-magnification SEM image of the surface of the lightweight gel material prepared in Example 4 of the present invention.

[0021] Figure 2 This is a medium-magnification SEM image of the surface of the lightweight gel material prepared in Example 4 of the present invention.

[0022] Figure 3 This is a high-magnification SEM image of the surface of the lightweight gel material prepared in Example 4 of the present invention.

[0023] Figure 4 The image shows the XRD pattern of the lightweight gel material prepared in Example 4 of this invention. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 A method for preparing a lightweight gel material for treating mine tailings includes the following steps: Step 1) Take 100g of short-cut basalt fibers (9mm in length and 15μm in diameter), put them into 2000mL of sodium hydroxide solution with a concentration of 1.5mol / L, and stir at 250rpm for 1.5h under constant temperature water bath at 75℃. After taking them out, rinse them repeatedly with deionized water until the pH of the washing solution is 7.0±0.5, and dry them in a forced air at 110℃ for 4h to obtain alkaline-etched basalt fibers.

[0026] Step 2) Mix 38 mL of tetraethyl orthosilicate, 160 mL of anhydrous ethanol and 20 mL of deionized water evenly, add 2 mL of 1 mol / L hydrochloric acid solution as a catalyst, and hydrolyze at 25 °C and 400 rpm for 3 h to obtain silica sol; immerse the alkaline-etched basalt fiber in the silica sol for 30 min, then remove it and dry it at 80 °C for 1 h. Repeat the immersion-drying operation 3 times in total, and then heat-treat it in a muffle furnace at 2 °C / min to 300 °C and hold for 2 h. After natural cooling, basalt fiber with a nano-silica coating on the surface is obtained.

[0027] Step 3) Dissolve 5g of γ-glycidoxypropyltrimethoxysilane in a mixture of 95mL of anhydrous ethanol and 5mL of deionized water, adjust the pH to 4.0 with glacial acetic acid, and stir and hydrolyze at 25℃ for 1h to obtain a coupling agent hydrolysate; immerse the fiber obtained in Step 2) in the coupling agent hydrolysate, stir and react at 65℃ for 2.5h, remove and wash 3 times with anhydrous ethanol, and cure at 120℃ for 2h to obtain modified basalt fiber.

[0028] Step 4) Disperse 50g of sodium-based montmorillonite in 1000mL of deionized water and stir at 2000rpm for 2h at 80℃ to allow it to fully swell and disperse. Separately, dissolve 21g of hexadecyltrimethylammonium bromide in 200mL of deionized water at 60℃ and slowly add it dropwise to the montmorillonite suspension. Continue stirring and reacting at 80℃ for 6h. Filter while hot and wash with deionized water at 60℃ until no bromide ions are detected in the filtrate (verified with silver nitrate solution). Dry at 60℃ for 24h and grind through a 300-mesh sieve to obtain organic intercalated montmorillonite powder.

[0029] Step 5) Disperse 40g of organic intercalated montmorillonite powder in 400mL of anhydrous toluene, ultrasonically disperse for 15min, then add 9g of γ-aminopropyltriethoxysilane, heat to 110℃ under nitrogen protection and reflux for 10h, filter while hot, wash three times each with anhydrous toluene and anhydrous ethanol, and dry at 80℃ and -0.08MPa vacuum for 12h to obtain silane-grafted montmorillonite.

[0030] Step 6) Dissolve 10g of sodium alginate in 200mL of 60℃ deionized water and stir until completely dissolved. Add 10.5g of silane-grafted montmorillonite, ultrasonically disperse for 30min, and stir at 60℃ for 4h to complete intercalation. Add 5mL of 25% glutaraldehyde aqueous solution and 2mL of glacial acetic acid to adjust the pH to 4.0-5.0, and stir at 50℃ for 3h to complete covalent cross-linking. Then slowly add 100mL of 0.15mol / L calcium chloride solution and continue stirring for 1h to complete ionic cross-linking. After filtration, wash three times with deionized water, pre-freeze at -50℃ for 24h, freeze-dry under vacuum for 48h, grind through a 200-mesh sieve to obtain montmorillonite / sodium alginate composite modifier powder.

[0031] Step 7) Add 400g of mine tailings (30% moisture content), 200g of ordinary Portland cement (PO 42.5 grade), 150g of Grade I fly ash, and 15g of silica fume to a mixer and dry mix for 2 minutes; separately, dissolve 5.5g of polyethylene glycol 600 in 80g of water glass (modulus 3.0, solid content 35%) and 270g of deionized water, mix evenly, and add to the dry mix, stirring at 500rpm for 5 minutes to form a slurry; add 25g of modified basalt fiber and 20g of montmorillonite / sodium alginate composite modifier powder to the slurry, and stir for 3 minutes to disperse evenly; dilute the animal protein-based foaming agent with 40 times the amount of water and foam to a density of 50kg / m³. 3 The foam was mixed with the slurry at a volume ratio of 3:1 (foam to slurry) and stirred at low speed for 2 minutes to achieve uniform mixing. The mixture was then poured into a steel triple mold (100mm×100mm×100mm). After micro-vibrating for 30 seconds to remove large air bubbles, the mixture was steam-cured at 60℃ and ≥95% humidity for 24 hours before demolding. Finally, it was cured at 20℃ and ≥95% humidity for 28 days to obtain a lightweight gel material.

[0032] Example 2 A method for preparing a lightweight gel material for treating mine tailings includes the following steps: Step 1) Take 100g of short-cut basalt fibers (9mm in length and 15μm in diameter), put them into 2000mL of sodium hydroxide solution with a concentration of 1.5mol / L, and stir at 250rpm for 1.5h under constant temperature water bath at 75℃. After taking them out, rinse them repeatedly with deionized water until the pH of the washing solution is 7.0±0.5, and dry them in a forced air at 110℃ for 4h to obtain alkaline-etched basalt fibers.

[0033] Step 2) Mix 33 mL of tetraethyl orthosilicate, 160 mL of anhydrous ethanol and 20 mL of deionized water evenly, add 2 mL of 1 mol / L hydrochloric acid solution as a catalyst, and hydrolyze at 25 °C and 400 rpm for 3 h to obtain silica sol; immerse the alkaline-etched basalt fiber in the silica sol for 30 min, then remove it and dry it at 80 °C for 1 h. Repeat the immersion-drying operation 3 times in total, and then heat-treat it in a muffle furnace at 2 °C / min to 300 °C and hold for 2 h. After natural cooling, basalt fiber with a nano-silica coating on the surface is obtained.

[0034] Step 3) Dissolve 5g of γ-glycidoxypropyltrimethoxysilane in a mixture of 95mL of anhydrous ethanol and 5mL of deionized water, adjust the pH to 4.0 with glacial acetic acid, and stir and hydrolyze at 25℃ for 1h to obtain a coupling agent hydrolysate; immerse the fiber obtained in Step 2) in the coupling agent hydrolysate, stir and react at 65℃ for 2.5h, remove and wash 3 times with anhydrous ethanol, and cure at 120℃ for 2h to obtain modified basalt fiber.

[0035] Step 4) Disperse 50g of sodium-based montmorillonite in 1000mL of deionized water and stir at 2000rpm for 2h at 80℃ to allow it to fully swell and disperse. Separately, dissolve 19g of hexadecyltrimethylammonium bromide in 200mL of deionized water at 60℃ and slowly add it dropwise to the montmorillonite suspension. Continue stirring and reacting at 80℃ for 6h. Filter while hot and wash with deionized water at 60℃ until no bromide ions are detected in the filtrate (verified with silver nitrate solution). Dry at 60℃ for 24h and grind through a 300-mesh sieve to obtain organic intercalated montmorillonite powder.

[0036] Step 5) Disperse 40g of organic intercalated montmorillonite powder in 400mL of anhydrous toluene, ultrasonically disperse for 15min, then add 7g of γ-aminopropyltriethoxysilane, heat to 110℃ under nitrogen protection and reflux for 10h, filter while hot, wash three times each with anhydrous toluene and anhydrous ethanol, and dry at 80℃ and -0.08MPa vacuum for 12h to obtain silane-grafted montmorillonite.

[0037] Step 6) Dissolve 10g of sodium alginate in 200mL of 60℃ deionized water and stir until completely dissolved. Add 9.5g of silane-grafted montmorillonite, ultrasonically disperse for 30min, and stir at 60℃ for 4h to complete intercalation. Add 5mL of 25% glutaraldehyde aqueous solution and 2mL of glacial acetic acid to adjust the pH to 4.0-5.0, and stir at 50℃ for 3h to complete covalent cross-linking. Then slowly add 100mL of 0.15mol / L calcium chloride solution and continue stirring for 1h to complete ionic cross-linking. After filtration, wash three times with deionized water, pre-freeze at -50℃ for 24h, freeze-dry under vacuum for 48h, grind through a 200-mesh sieve to obtain montmorillonite / sodium alginate composite modifier powder.

[0038] Step 7) Add 400g of mine tailings (30% moisture content), 200g of ordinary Portland cement (PO 42.5 grade), 150g of Grade I fly ash, and 15g of silica fume to a mixer and dry mix for 2 minutes; separately, dissolve 4.5g of polyethylene glycol 600 in 80g of water glass (modulus 3.0, solid content 35%) and 270g of deionized water, mix evenly, and add to the dry mix, stirring at 500rpm for 5 minutes to form a slurry; add 25g of modified basalt fiber and 20g of montmorillonite / sodium alginate composite modifier powder to the slurry, and stir for 3 minutes to disperse evenly; dilute the animal protein-based foaming agent with 40 times the amount of water and foam to a density of 50kg / m³. 3The foam was mixed with the slurry at a volume ratio of 3:1 (foam to slurry) and stirred at low speed for 2 minutes to achieve uniform mixing. The mixture was then poured into a steel triple mold (100mm×100mm×100mm). After micro-vibrating for 30 seconds to remove large air bubbles, the mixture was steam-cured at 60℃ and ≥95% humidity for 24 hours before demolding. Finally, it was cured at 20℃ and ≥95% humidity for 28 days to obtain a lightweight gel material.

[0039] Example 3 A method for preparing a lightweight gel material for treating mine tailings includes the following steps: Step 1) Take 100g of short-cut basalt fibers (9mm in length and 15μm in diameter), put them into 2000mL of sodium hydroxide solution with a concentration of 1.5mol / L, and stir at 250rpm for 1.5h under constant temperature water bath at 75℃. After taking them out, rinse them repeatedly with deionized water until the pH of the washing solution is 7.0±0.5, and dry them in a forced air at 110℃ for 4h to obtain alkaline-etched basalt fibers.

[0040] Step 2) Mix 35 mL of tetraethyl orthosilicate, 160 mL of anhydrous ethanol and 20 mL of deionized water evenly, add 2 mL of 1 mol / L hydrochloric acid solution as a catalyst, and hydrolyze at 25 °C and 400 rpm for 3 h to obtain silica sol; immerse the alkaline-etched basalt fiber in the silica sol for 30 min, then remove it and dry it at 80 °C for 1 h. Repeat the immersion-drying operation 3 times in total, and then heat-treat it in a muffle furnace at 2 °C / min to 300 °C and hold for 2 h. After natural cooling, basalt fiber with a nano-silica coating on the surface is obtained.

[0041] Step 3) Dissolve 5g of γ-glycidoxypropyltrimethoxysilane in a mixture of 95mL of anhydrous ethanol and 5mL of deionized water, adjust the pH to 4.0 with glacial acetic acid, and stir and hydrolyze at 25℃ for 1h to obtain a coupling agent hydrolysate; immerse the fiber obtained in Step 2) in the coupling agent hydrolysate, stir and react at 65℃ for 2.5h, remove and wash 3 times with anhydrous ethanol, and cure at 120℃ for 2h to obtain modified basalt fiber.

[0042] Step 4) Disperse 50g of sodium-based montmorillonite in 1000mL of deionized water and stir at 2000rpm for 2h at 80℃ to allow it to fully swell and disperse. Separately, dissolve 20g of hexadecyltrimethylammonium bromide in 200mL of deionized water at 60℃ and slowly add it dropwise to the montmorillonite suspension. Continue stirring and reacting at 80℃ for 6h. Filter while hot and wash with deionized water at 60℃ until no bromide ions are detected in the filtrate (verified with silver nitrate solution). Dry at 60℃ for 24h and grind through a 300-mesh sieve to obtain organic intercalated montmorillonite powder.

[0043] Step 5) Disperse 40g of organic intercalated montmorillonite powder in 400mL of anhydrous toluene, ultrasonically disperse for 15min, then add 8g of γ-aminopropyltriethoxysilane, heat to 110℃ under nitrogen protection and reflux for 10h, filter while hot, wash three times each with anhydrous toluene and anhydrous ethanol, and dry at 80℃ and -0.08MPa vacuum for 12h to obtain silane-grafted montmorillonite.

[0044] Step 6) Dissolve 10g of sodium alginate in 200mL of 60℃ deionized water and stir until completely dissolved. Add 10g of silane-grafted montmorillonite, ultrasonically disperse for 30min, and stir at 60℃ for 4h to complete intercalation. Add 5mL of 25% glutaraldehyde aqueous solution and 2mL of glacial acetic acid to adjust the pH to 4.0-5.0, and stir at 50℃ for 3h to complete covalent cross-linking. Then slowly add 100mL of 0.15mol / L calcium chloride solution and continue stirring for 1h to complete ionic cross-linking. After filtration, wash three times with deionized water, pre-freeze at -50℃ for 24h, and then freeze-dry under vacuum for 48h. Grind and pass through a 200-mesh sieve to obtain montmorillonite / sodium alginate composite modifier powder.

[0045] Step 7) Add 400g of mine tailings (30% moisture content), 200g of ordinary Portland cement (PO 42.5 grade), 150g of Grade I fly ash, and 15g of silica fume to a mixer and dry mix for 2 minutes; separately, dissolve 5g of polyethylene glycol 600 in 80g of water glass (modulus 3.0, solid content 35%) and 270g of deionized water, mix evenly, and add to the dry mix. Stir at 500rpm for 5 minutes to form a slurry; add 25g of modified basalt fiber and 20g of montmorillonite / sodium alginate composite modifier powder to the slurry and stir for 3 minutes to disperse evenly; dilute the animal protein-based foaming agent with 40 times the amount of water and foam to a density of 50kg / m³. 3 The foam was mixed with the slurry at a volume ratio of 3:1 (foam to slurry) and stirred at low speed for 2 minutes to achieve uniform mixing. The mixture was then poured into a steel triple mold (100mm×100mm×100mm). After micro-vibrating for 30 seconds to remove large air bubbles, the mixture was steam-cured at 60℃ and ≥95% humidity for 24 hours before demolding. Finally, it was cured at 20℃ and ≥95% humidity for 28 days to obtain a lightweight gel material.

[0046] Example 4 A method for preparing a lightweight gel material for treating mine tailings includes the following steps: Step 1) Take 100g of short-cut basalt fibers (9mm in length and 15μm in diameter), put them into 2000mL of sodium hydroxide solution with a concentration of 2mol / L, and stir at 250rpm for 2h under constant temperature water bath at 80℃. After taking them out, rinse them repeatedly with deionized water until the pH of the washing solution is 7.0±0.5, and dry them in a forced air at 110℃ for 4h to obtain alkaline-etched basalt fibers.

[0047] Step 2) Mix 40 mL of tetraethyl orthosilicate, 160 mL of anhydrous ethanol and 20 mL of deionized water evenly, add 2 mL of 1 mol / L hydrochloric acid solution as a catalyst, and hydrolyze at 25 °C and 400 rpm for 3 h to obtain silica sol; immerse the alkaline-etched basalt fiber in the silica sol for 30 min, remove it, dry it at 80 °C for 1 h, repeat the immersion-drying operation 3 times, and then heat-treat it in a muffle furnace at 2 °C / min to 300 °C for 2 h, and cool it naturally to obtain basalt fiber with a nano-silica coating on the surface.

[0048] Step 3) Dissolve 5g of γ-glycidoxypropyltrimethoxysilane in a mixture of 95mL of anhydrous ethanol and 5mL of deionized water, adjust the pH to 4.0 with glacial acetic acid, and stir and hydrolyze at 25℃ for 1h to obtain a coupling agent hydrolysate; immerse the fiber obtained in Step 2) in the coupling agent hydrolysate, stir and react at 70℃ for 3h, remove and wash 3 times with anhydrous ethanol, and cure at 120℃ for 2h to obtain modified basalt fiber.

[0049] Step 4) Disperse 50g of sodium montmorillonite in 1000mL of deionized water and stir at 2000rpm for 2h at 80℃ to allow it to fully swell and disperse. Separately, dissolve 22g of hexadecyltrimethylammonium bromide in 200mL of deionized water at 60℃ and slowly add it dropwise to the montmorillonite suspension. Continue stirring and reacting at 80℃ for 6h. Filter while hot and wash with deionized water at 60℃ until no bromide ions are detected in the filtrate (verified with silver nitrate solution). Dry at 60℃ for 24h and grind through a 300-mesh sieve to obtain organic intercalated montmorillonite powder.

[0050] Step 5) Disperse 40g of organic intercalated montmorillonite powder in 400mL of anhydrous toluene, ultrasonically disperse for 15min, add 10g of γ-aminopropyltriethoxysilane, heat to 110℃ under nitrogen protection and reflux for 10h, filter while hot, wash three times each with anhydrous toluene and anhydrous ethanol, and dry at 80℃ and -0.08MPa vacuum for 12h to obtain silane-grafted montmorillonite.

[0051] Step 6) Dissolve 10g of sodium alginate in 200mL of 60℃ deionized water and stir until completely dissolved. Add 11g of silane-grafted montmorillonite, ultrasonically disperse for 30min, and stir at 60℃ for 4h to complete intercalation. Add 5mL of 25% glutaraldehyde aqueous solution and 2mL of glacial acetic acid to adjust the pH to 4.0-5.0, and stir at 50℃ for 3h to complete covalent cross-linking. Then slowly add 100mL of 0.2mol / L calcium chloride solution and continue stirring for 1h to complete ionic cross-linking. After filtration, wash three times with deionized water, pre-freeze at -50℃ for 24h, freeze-dry under vacuum for 48h, grind through a 200-mesh sieve to obtain montmorillonite / sodium alginate composite modifier powder.

[0052] Step 7) Add 400g of mine tailings (30% moisture content), 200g of ordinary Portland cement (PO 42.5 grade), 150g of Grade I fly ash, and 15g of silica fume to a mixer and dry mix for 2 minutes; separately dissolve 6g of polyethylene glycol 600 in 80g of water glass (modulus 3.0, solid content 35%) and 270g of deionized water, mix evenly, and add to the dry mix, stirring at 500rpm for 5 minutes to form a slurry; add 25g of modified basalt fiber and 20g of montmorillonite / sodium alginate composite modifier powder to the slurry, and stir for 3 minutes to disperse evenly; dilute the animal protein-based foaming agent with 40 times the amount of water and foam to a density of 50kg / m³. 3 The foam was mixed with the slurry at a volume ratio of 3:1 (foam to slurry) and stirred at low speed for 2 minutes to achieve uniform mixing. The mixture was then poured into a steel triple mold (100mm×100mm×100mm). After micro-vibrating for 30 seconds to remove large air bubbles, the mixture was steam-cured at 60℃ and ≥95% humidity for 24 hours before demolding. Finally, it was cured at 20℃ and ≥95% humidity for 28 days to obtain a lightweight gel material.

[0053] Example 5 A method for preparing a lightweight gel material for treating mine tailings includes the following steps: Step 1) Take 100g of short-cut basalt fibers (9mm in length and 15μm in diameter), put them into 2000mL of sodium hydroxide solution with a concentration of 1mol / L, and stir at 250rpm for 1h under constant temperature water bath at 70℃. After taking them out, rinse them repeatedly with deionized water until the pH of the washing solution is 7.0±0.5, and dry them in a forced air at 110℃ for 4h to obtain alkaline-etched basalt fibers.

[0054] Step 2) Mix 30 mL of tetraethyl orthosilicate, 160 mL of anhydrous ethanol and 20 mL of deionized water evenly, add 2 mL of 1 mol / L hydrochloric acid solution as a catalyst, and hydrolyze at 25 °C and 400 rpm for 3 h to obtain silica sol; immerse the alkaline-etched basalt fiber in the silica sol for 30 min, then remove it and dry it at 80 °C for 1 h. Repeat the immersion-drying operation 3 times in total, and then heat-treat it in a muffle furnace at 2 °C / min to 300 °C and hold for 2 h. After natural cooling, basalt fiber with a nano-silica coating on the surface is obtained.

[0055] Step 3) Dissolve 5g of γ-glycidoxypropyltrimethoxysilane in a mixture of 95mL of anhydrous ethanol and 5mL of deionized water, adjust the pH to 4.0 with glacial acetic acid, and stir and hydrolyze at 25℃ for 1h to obtain a coupling agent hydrolysate; immerse the fiber obtained in Step 2) in the coupling agent hydrolysate, stir and react at 60℃ for 2h, remove and wash 3 times with anhydrous ethanol, and cure at 120℃ for 2h to obtain modified basalt fiber.

[0056] Step 4) Disperse 50g of sodium montmorillonite in 1000mL of deionized water and stir at 2000rpm for 2h at 80℃ to allow it to fully swell and disperse. Separately, dissolve 18g of hexadecyltrimethylammonium bromide in 200mL of deionized water at 60℃ and slowly add it dropwise to the montmorillonite suspension. Continue stirring and reacting at 80℃ for 6h. Filter while hot and wash with deionized water at 60℃ until no bromide ions are detected in the filtrate (verified with silver nitrate solution). Dry at 60℃ for 24h and grind through a 300-mesh sieve to obtain organic intercalated montmorillonite powder.

[0057] Step 5) Disperse 40g of organic intercalated montmorillonite powder in 400mL of anhydrous toluene, sonicate for 15min, add 6g of γ-aminopropyltriethoxysilane, heat to 110℃ under nitrogen protection and reflux for 10h, filter while hot, wash three times each with anhydrous toluene and anhydrous ethanol, and dry at 80℃ and -0.08MPa vacuum for 12h to obtain silane-grafted montmorillonite.

[0058] Step 6) Dissolve 10g of sodium alginate in 200mL of 60℃ deionized water and stir until completely dissolved. Add 9g of silane-grafted montmorillonite, ultrasonically disperse for 30min, and stir at 60℃ for 4h to complete intercalation. Add 5mL of 25% glutaraldehyde aqueous solution and 2mL of glacial acetic acid to adjust the pH to 4.0-5.0, and stir at 50℃ for 3h to complete covalent cross-linking. Then slowly add 100mL of 0.1mol / L calcium chloride solution and continue stirring for 1h to complete ionic cross-linking. After filtration, wash three times with deionized water, pre-freeze at -50℃ for 24h, freeze-dry under vacuum for 48h, grind through a 200-mesh sieve to obtain montmorillonite / sodium alginate composite modifier powder.

[0059] Step 7) Add 400g of mine tailings (30% moisture content), 200g of ordinary Portland cement (PO 42.5 grade), 150g of Grade I fly ash, and 15g of silica fume to a mixer and dry mix for 2 minutes; separately dissolve 4g of polyethylene glycol 600 in 80g of water glass (modulus 3.0, solid content 35%) and 270g of deionized water, mix evenly, and add to the dry mix, stirring at 500rpm for 5 minutes to form a slurry; add 25g of modified basalt fiber and 20g of montmorillonite / sodium alginate composite modifier powder to the slurry, and stir for 3 minutes to disperse evenly; dilute the animal protein-based foaming agent with 40 times the amount of water and foam to a density of 50kg / m³. 3 The foam was mixed with the slurry at a volume ratio of 3:1 (foam to slurry) and stirred at low speed for 2 minutes to achieve uniform mixing. The mixture was then poured into a steel triple mold (100mm×100mm×100mm). After micro-vibrating for 30 seconds to remove large air bubbles, the mixture was steam-cured at 60℃ and ≥95% humidity for 24 hours before demolding. Finally, it was cured at 20℃ and ≥95% humidity for 28 days to obtain a lightweight gel material.

[0060] Comparative Example 1: The difference between Comparative Example 1 and Example 4 is that: in step 7), modified basalt fiber and montmorillonite / sodium alginate composite modifier powder are not added, and silica fume and polyethylene glycol 600 are not added. The other raw material types, amounts and process conditions are the same as in Example 4, and a lightweight gel material is obtained.

[0061] Comparative Example 2: The difference between Comparative Example 2 and Example 4 is that only 25g of modified basalt fiber was added in step 7), and no montmorillonite / sodium alginate composite modifier powder was added. At the same time, no silica fume and polyethylene glycol 600 were added. The other raw material types, dosages and process conditions were the same as in Example 4, and a lightweight gel material was obtained.

[0062] Comparative Example 3: The difference between Comparative Example 3 and Example 4 is that only 20g of montmorillonite / sodium alginate composite modifier powder was added in step 7), and no modified basalt fiber was added. At the same time, silica fume and polyethylene glycol 600 were not added. The other raw material types, dosages and process conditions were the same as in Example 4, and a lightweight gel material was obtained.

[0063] Comparative Example 4: The difference between Comparative Example 4 and Example 4 is that in step 7), 25g of modified basalt fiber and 20g of montmorillonite / sodium alginate composite modifier powder are added simultaneously, but silica fume and polyethylene glycol 600 are not added. The other raw material types, amounts and process conditions are the same as in Example 4, and a lightweight gel material is obtained.

[0064] Comparative Example 5: The difference between Comparative Example 5 and Example 4 is that 15g of silica fume was added in step 7), but polyethylene glycol 600 was not added. The other raw material types, amounts and process conditions were the same as in Example 4, and a lightweight gel material was obtained.

[0065] Comparative Example 6: The difference between Comparative Example 6 and Example 4 is that 6g of polyethylene glycol 600 was added in step 7), but silica fume was not added. The other raw material types, amounts and process conditions were the same as in Example 4, and a lightweight gel material was obtained.

[0066] Comparative Example 7: The difference between Comparative Example 7 and Example 4 is that in step 7), 25g of unmodified raw short-cut basalt fibers (9mm in length and 15μm in diameter) were directly added to the slurry instead of modified basalt fibers, i.e., the alkaline etching, nano-silica coating and silane coupling agent grafting treatments in steps 1) to 3) were not performed. The other raw material types, amounts and process conditions were the same as in Example 4, and a lightweight gel material was obtained.

[0067] Comparative Example 8: The difference between Comparative Example 8 and Example 4 is that in step 7), 20g of unmodified raw sodium-based montmorillonite powder (ground through a 200-mesh sieve) was directly added to the slurry instead of montmorillonite / sodium alginate composite modifier powder. That is, the organic intercalation, silane grafting and sodium alginate double crosslinking treatment in steps 4) to 6) were not performed. The other raw material types, amounts and process conditions were the same as in Example 4, and a lightweight gel material was obtained.

[0068] Performance testing: 1. Dry density test: 100mm × 100mm × 100mm cubic specimens cured to 28 days were removed from the standard curing room and placed in a forced-air drying oven at 105±5℃ for continuous drying. They were weighed every 24 hours until the mass difference between two consecutive weighings did not exceed 0.1% of the previous mass, at which point constant weight was considered reached. The constant weight mass m (g) was recorded. Using vernier calipers, a set of length, width, and height values ​​(accurate to 0.1mm) were measured at the midpoint of each of the three pairs of opposite faces of the specimen. The average value in each direction was used to calculate the specimen volume V (cm³). 3 The dry density ρ0 is calculated using the formula ρ0=m / V. The arithmetic mean of the test results of 3 specimens in each group is taken, accurate to 1 kg / m³. 3 .

[0069] 2.28-day compressive strength test: Remove the 100mm×100mm×100mm cube specimens cured to 28 days of standard curing. Wipe the surface clean with a damp cloth and inspect the specimen for obvious defects. Place the specimen at the center of the lower platen of a computer-controlled universal compression testing machine, with the loading surface being the side surface as it was during casting. The upper and lower plates should be in full contact with the end faces of the specimen without eccentricity. Apply a continuous and uniform load at a rate of 0.5 kN / s until the specimen fails, and record the failure load F (N). The compressive strength f is then measured. c According to formula f c =F / A, where A is the area of ​​the pressure-bearing surface of the specimen (mm²).2 For each group, the arithmetic mean of the test results of 3 specimens is taken, accurate to 0.01 MPa.

[0070] 3.28-day flexural strength test: For each embodiment and comparative example, while preparing 100mm×100mm×100mm cubic compressive strength specimens, 100mm×100mm×400mm prism specimens were also prepared using the same formula and curing conditions, with at least three specimens per group. The prism specimens, cured to 28 days, were removed, their surfaces cleaned, and subjected to a three-point bending load on a universal testing machine. The span between the two support rollers was 300mm, the loading point was at the mid-span, and the cast side of the specimen faced upwards as the tension surface. A continuous and uniform loading rate of 50 N / s was applied until the specimen broke, and the failure load F (N) was recorded. The flexural strength f_f was calculated using the formula f = 3FL / (2bh). 2 The calculation is performed, where F is the failure load (N), L is the span (mm), b is the specimen cross-sectional width (mm), and h is the specimen cross-sectional height (mm). The arithmetic mean of the test results of 3 specimens in each group is taken, accurate to 0.01MPa.

[0071] 4. Water Absorption Test: 100mm×100mm×100mm cubic specimens cured to 28 days were dried in a forced-air drying oven at 105±5℃ until constant weight was achieved. The dried mass m0 (g) was recorded. The specimen dimensions were measured using vernier calipers, and the volume V0 (cm³) was calculated. 3 The dried specimen was then completely immersed in deionized water at 20±2℃, with the water level always 20mm above the top surface of the specimen. The specimen was removed after 24h, 48h, and 72h of immersion. The surface water was quickly wiped away with a damp cloth, and the specimen was weighed. Water saturation was defined as the difference between two consecutive weighings not exceeding 0.2% of the previous weighing, and the saturated mass m was recorded. s (g). Mass water absorption rate W m According to formula W m =(m s Calculate using (-m0) / m0×100%, and take the average value of 3 specimens in each group, accurate to 0.1%.

[0072] 5. Softening coefficient test: Six 100mm×100mm×100mm cubic specimens were prepared for each group and cured for 28 days. The compressive strength f of three of them was measured under dry conditions (dried at 105℃ to constant weight and then naturally cooled to room temperature). dry The compressive strength f of the other three samples was measured under saturated water conditions (completely submerged in deionized water at 20±2℃ until saturated, then removed and the surface water was wiped off). sat The test method is the same as the compressive strength test in item 2 above. The softening coefficient Ks is calculated using the formula Ks=f sat / f dryCalculate, where f dry and f sat Take the arithmetic mean of the three specimens respectively, and Ks is accurate to 0.01.

[0073] Table 1: Performance Test Results of Examples and Comparative Examples

[0074] From the table above, we can obtain: (1) Comparative Example 1 is a blank matrix without any modified components. Its 28-day compressive strength is only 1.38 MPa, its flexural strength is only 0.29 MPa, its water absorption rate is as high as 38.2%, and its softening coefficient is only 0.52. This indicates that the mechanical properties and water resistance of the simple cement-fly ash-tails system are seriously insufficient after lightweighting.

[0075] (2) Comparative Examples 2 and 3 verified the individual reinforcing effects of modified basalt fiber and montmorillonite / sodium alginate composite modifier, respectively. The compressive strength of Comparative Example 2 was 2.53 MPa, and the water absorption rate decreased to 31.5%; the compressive strength of Comparative Example 3 was 2.17 MPa, and the water absorption rate decreased to 33.1%. Both showed significant improvements compared to Comparative Example 1, indicating that the three-layer interface engineering of the modified fiber and the organic-inorganic interpenetrating network structure of the composite modifier can effectively improve the mechanical strength of the lightweight gel material and improve its pore structure density.

[0076] (3) Comparative Example 4, without the addition of silica fume and polyethylene glycol 600, had a 28-day compressive strength of 3.02 MPa. The compressive strength enhancement contributions of Comparative Examples 2 and 3 relative to Comparative Example 1 were 1.15 MPa and 0.79 MPa, respectively. Theoretically, the combined compressive strength of the two should reach approximately 3.32 MPa, but Comparative Example 4 actually only reached 3.02 MPa, which is 0.30 MPa lower than the theoretical combined value. This confirms that there is indeed a loss of synergistic efficiency between the two modified components due to insufficient interfacial wetting compatibility.

[0077] (4) Comparative Example 5, with the addition of only silica fume without polyethylene glycol 600, achieved a compressive strength of 3.48 MPa and a softening coefficient of 0.75; Comparative Example 6, with the addition of only polyethylene glycol 600 without silica fume, achieved a compressive strength of 3.12 MPa and a softening coefficient of 0.71. Both were superior to Comparative Example 4 (3.02 MPa, 0.69), indicating that both silica fume and polyethylene glycol can partially improve interfacial compatibility. However, the performance of both when used alone was significantly lower than that of Example 4 (4.13 MPa, 0.82), proving that the rigid filling-chemical bonding mechanism of silica fume and the flexible bridging-compatibility mechanism of polyethylene glycol are both indispensable and must work synergistically to maximize the elimination of interfacial defects.

[0078] (5) In Comparative Example 7, unmodified basalt fibers were directly replaced with modified basalt fibers. The compressive strength was only 2.08 MPa, significantly lower than that of Example 4 (4.13 MPa) using modified fibers. At the same time, its water absorption (34.6%) and softening coefficient (0.58) were also poor. This indicates that the interfacial bonding force between the original smooth fibers and the gel matrix is ​​insufficient, and the load cannot be effectively transferred to the fiber skeleton. The three-layer gradient interfacial engineering treatment of alkali etching-nanocoating-silane grafting in steps 1) to 3) is indispensable for the full realization of the fiber reinforcement effect.

[0079] (6) Comparative Example 8, which directly replaced the composite modifier with unmodified montmorillonite, had a compressive strength of only 1.86 MPa, even lower than Comparative Example 2 (2.53 MPa with only modified fiber). Its water absorption rate was as high as 35.8%, and its softening coefficient was only 0.55. This indicates that the untreated montmorillonite, due to its narrow interlayer spacing, poor dispersion in the matrix, and lack of organic-inorganic interpenetrating network crack deflection and energy dissipation mechanism, not only failed to play a toughening and strengthening role, but also weakened the matrix structure due to defects introduced by agglomeration. The organic intercalation-silane grafting-double crosslinking modification treatment in steps 4) to 6) is crucial for constructing an effective nanosheet toughening network.

[0080] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the essence and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a lightweight gel material for treating mine tailings, characterized in that, Includes the following steps: 1) Short-cut basalt fibers were alkali-etched and activated with sodium hydroxide solution, washed with water until neutral, and then dried to obtain alkali-etched basalt fibers; 2) A silica sol was prepared by using tetraethyl orthosilicate, anhydrous ethanol, deionized water and hydrochloric acid. The alkaline-etched basalt fibers were subjected to repeated impregnation-drying cycles and then heat treatment to obtain basalt fibers with a nano-silica coating on the surface. 3) Prepare a coupling agent hydrolysate by mixing γ-glycidyl etheroxypropyltrimethoxysilane, anhydrous ethanol, deionized water and glacial acetic acid. Immerse the fiber obtained in step 2) in the solution and react. After washing and curing, the modified basalt fiber is obtained. 4) Disperse sodium-based montmorillonite in deionized water and react it with hexadecyltrimethylammonium bromide via ion exchange. After washing, drying, grinding and sieving, organic intercalated montmorillonite powder is obtained. 5) Disperse organic intercalated montmorillonite powder in anhydrous toluene, add γ-aminopropyltriethoxysilane, heat under nitrogen protection and reflux reaction, and obtain silane-grafted montmorillonite after washing and vacuum drying; 6) Dissolve sodium alginate in deionized water, add silane-grafted montmorillonite for intercalation dispersion, add glutaraldehyde and calcium chloride solution in sequence for double cross-linking reaction, and obtain montmorillonite / sodium alginate composite modifier powder after freeze drying, grinding and sieving. 7) Mix the mine tailings, ordinary silicate cement, fly ash and silica fume evenly, add the liquid component consisting of polyethylene glycol, water glass and deionized water and stir to form a slurry. Then add modified basalt fiber and montmorillonite / sodium alginate composite modifier powder to the slurry and mix well. After adding foam, pour and mold it. After curing, the lightweight gel material is obtained.

2. The method for preparing a lightweight gel material for treating mine tailings according to claim 1, characterized in that, In step 1), the concentration of the sodium hydroxide solution is 1–2 mol / L; The alkaline etching activation treatment temperature is 70-80℃, and the time is 1-2 hours.

3. The method for preparing a lightweight gel material for treating mine tailings according to claim 1, characterized in that, In step 2), the volume ratio of tetraethyl orthosilicate, anhydrous ethanol, and deionized water is (30-40):160:

20.

4. The method for preparing a lightweight gel material for treating mine tailings according to claim 1, characterized in that, In step 3), the reaction temperature is 60-70℃ and the reaction time is 2-3h.

5. The method for preparing a lightweight gel material for treating mine tailings according to claim 1, characterized in that, In step 4), the mass ratio of sodium montmorillonite to hexadecyltrimethylammonium bromide is 50:(18-22).

6. The method for preparing a lightweight gel material for treating mine tailings according to claim 1, characterized in that, In step 5), the mass ratio of the organic intercalated montmorillonite powder to γ-aminopropyltriethoxysilane is 40:(6-10).

7. The method for preparing a lightweight gel material for treating mine tailings according to claim 1, characterized in that, In step 6), the mass ratio of sodium alginate to silane-grafted montmorillonite is 10:(9-11).

8. The method for preparing a lightweight gel material for treating mine tailings according to claim 1, characterized in that, In step 6), the concentration of the calcium chloride solution is 0.1–0.2 mol / L.

9. The method for preparing a lightweight gel material for treating mine tailings according to claim 1, characterized in that, In step 7), the mass ratio of silica fume to polyethylene glycol is 15:(4-6).

10. A lightweight gel material for treating mine tailings, characterized in that, It is prepared by the method described in any one of claims 1 to 9 above.

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