A kind of binder applied to mine slag bonding

Abstract

The application relates to a binder applied to mine slag adhesion, which comprises the following components: 65-70 parts of mine slag, 8-12 parts of calcium aluminate cement, 3-5 parts of mine powder, 2-3 parts of phosphorus powder, 1.5-2.5 parts of water glass, 0.8-1.2 parts of sodium hydroxide, 0.6-0.8 parts of a retarder, and 2-5 parts of an alkaline additive; the alkaline additive comprises modified calcium hydroxide, sodium silicate and sodium carbonate; the modified calcium hydroxide comprises calcium hydroxide and sodium polyphosphate. The application has the effects of improving the cement solidification and adhesion performance, reducing heavy metal ion seepage, and improving the utilization rate of mine slag.

Description

Technical Field

[0001] This application relates to the field of interdisciplinary technology of environmental engineering and chemical materials, and is mainly applied to the application scenario of mine restoration and management, especially to an adhesive for bonding mine slag. Background Technology

[0002] During the initial processing of raw ore in mining operations (such as smelting, incineration, and flotation), a large amount of highly toxic waste (such as red mud, tailings, and filter residue) is generated. This waste contains harmful components such as heavy metals (As, Pb, Cd) and cyanides, posing a serious threat to the environment and human health.

[0003] The most common solution for treating mine waste is to solidify it with cement and then landfill it. This involves crushing and screening the mine waste to remove large impurities, mixing the cement with the pretreated waste, curing it, and then landfilling it to isolate the waste from direct contact with the external environment.

[0004] However, cement has weak bonding with waste materials, making it prone to heavy metal leaching due to shrinkage cracks, which can further pollute the surrounding environment. In addition, chlorides and sulfates can damage the structure of cement stone, causing waste to leach out. Moreover, cement itself has high carbon emissions during production (0.73-0.99 tons of CO2 / ton), making it difficult to further achieve the goal of low-carbon and environmental protection. Summary of the Invention

[0005] In order to further activate the aluminosilicate reaction and improve the bonding performance between cement and waste, this application provides an adhesive for bonding mine slag.

[0006] The adhesive for bonding mine slag provided in this application adopts the following technical solution:

[0007] An adhesive for bonding mine slag comprises 65-70 parts of slag, 8-12 parts of calcium aluminate cement, 3-5 parts of mineral powder, 2-3 parts of phosphorus powder, 1.5-2.5 parts of water glass, 0.8-1.2 parts of sodium hydroxide, 0.6-0.8 parts of retarder, and 2-5 parts of alkaline additive.

[0008] The alkaline additive includes modified calcium hydroxide, sodium silicate, and sodium carbonate, wherein the modified calcium hydroxide includes calcium hydroxide and sodium polymethphosphate.

[0009] By adopting the above technical solution, after adding alkaline additives to the system, sodium silicate plays the role of supplementing silicon source and accelerating gel formation, improving the reaction efficiency of sodium carbonate and aluminosilicate. Sodium carbonate assists the alkaline source, fills the micropores of CSH gel, and improves the density of the system. Modified calcium hydroxide is prepared by calcium hydroxide and sodium polymethphosphate, forming a calcium phosphate coating on the surface of calcium hydroxide, preventing particle agglomeration, stabilizing its dispersion, improving the overall stability of the system, and phosphate ions can form phosphate precipitates with extremely low solubility, reducing the leaching of metal ions, activating the reaction of aluminosilicate, improving the bonding performance between various components of the system, improving the overall compressive strength of the system, and effectively reducing the amount of binder. It also protects the mine ecology in a green and environmentally friendly way and reduces carbon emissions in the process of mine waste treatment.

[0010] Preferably, the modified calcium hydroxide is prepared by the following method:

[0011] Calcium hydroxide was mixed and dispersed with water to obtain a calcium hydroxide solution. Sodium polyphosphate was mixed with water to obtain a sodium polyphosphate dispersion. The sodium polyphosphate dispersion was added to the calcium hydroxide solution and stirred. Then, the mixture was centrifuged, the supernatant was removed, and after washing, it was freeze-dried to obtain modified calcium hydroxide.

[0012] By adopting the above technical solution, the calcium phosphate shell formed on the surface of modified calcium hydroxide has extremely high specific surface area and chemical activity. The Ca²⁺ on its surface can undergo exchange reaction with metal ions. At the same time, the unreacted polymetaphosphate long chain itself is a very strong heavy metal chelating agent, which fixes metal ions, reduces the leaching of metal ions, and improves mechanical properties.

[0013] Preferably, the mass ratio of calcium hydroxide to sodium polyphosphate is 1:(0.14-0.18).

[0014] By adopting the above technical solution, and optimizing the mass ratio between calcium hydroxide and sodium polyphosphate within the above range, the agglomeration of calcium hydroxide is effectively reduced, and the overall stability of the modified calcium hydroxide is improved.

[0015] Preferably, the mass ratio of the modified calcium hydroxide, sodium carbonate and sodium silicate is (1.4-1.8):1:0.67.

[0016] By adopting the above technical solution, and preferably within the above-mentioned range the mass ratio of modified calcium hydroxide, sodium carbonate and sodium silicate, the bonding strength between the alkaline additive and the slag components is improved, and the leaching of metal ions can be further reduced.

[0017] Preferably, the product also includes a tannic acid composite component, which comprises tannic acid gel and silica, wherein the tannic acid gel raw material comprises tannic acid and lipoic acid.

[0018] By employing the above technical solution, tannic acid, which contains phenolic hydroxyl groups, reacts with free Ca in the system. 2+ Na + Electrostatic adsorption is formed, accelerating the process of Ca. 2+ The migration of zinc ions to the slag surface increases the activity activation rate of the slag and enhances the formation efficiency of CSH, further improving the interfacial bonding between the binder and the slag. Zinc ions in thioctic acid can accelerate the formation of Al in the slag. 3+ It dissolves and promotes the formation of gels with silica and calcium ions, thereby improving the bonding performance and durability. Furthermore, silica can directly form a synergistic effect with modified calcium hydroxide to activate the aluminosilicate reaction, further improving the bonding performance and mechanical strength of the adhesive.

[0019] Preferably, the tannic acid gel is prepared by the following method:

[0020] Tris(hydroxymethyl)aminomethane was mixed with water to obtain a tris(hydroxymethyl)aminomethane solution. The tris(hydroxymethyl)aminomethane solution was mixed with tannic acid to obtain a tannic acid solution. Lipoic acid was added to the tannic acid solution and stirred. The mixture was heated until it became viscous, then frozen and thawed to obtain a tannic acid gel.

[0021] By adopting the above technical solution, a large number of phenolic hydroxyl groups in tannic acid molecules form stable coordination bonds with the surface of modified calcium hydroxide. At the same time, phosphate groups also participate in coordination to form a ternary coordination structure, which significantly enhances the interfacial bonding force between the gel and modified calcium hydroxide. The tannic acid gel condenses with sodium silicate to form a network structure, which significantly improves the crack resistance and durability of the slag.

[0022] Preferably, the mass ratio of tannic acid to lipoic acid is (4.6-4.9):1.

[0023] By adopting the above technical solution, and preferably within the above-mentioned range the mass ratio of lipoic acid to tannic acid, the prepared tannic acid gel has better stability.

[0024] Preferably, the tannic acid composite component is prepared by the following method:

[0025] Tannic acid gel was mixed with methylpyrrolidone to obtain a gel solution. Silica was added to the gel solution, ultrasonically dispersed, and then dried to obtain the tannic acid composite component.

[0026] Preferably, the mass ratio of the tannic acid gel to silica is 1:(0.15-0.19).

[0027] By adopting the above technical solution, and preferably within the above-mentioned range the mass ratio between tannic acid gel and silica, the overall stability of the prepared tannic acid composite component can be further improved.

[0028] Preferably, the mass ratio between the alkaline additive and the tannic acid composite component is 1:(0.65-0.75).

[0029] By adopting the above technical solution, and optimizing the mass ratio between alkaline additives and tannic acid composite components within the above range, the synergistic effect between the components can be better enhanced, and the bonding performance between cement and waste can be further improved.

[0030] In summary, this application includes at least one of the following beneficial technical effects:

[0031] In alkaline additives, sodium silicate plays the role of supplementing silicon source and accelerating gel formation, improving the reaction efficiency of sodium carbonate and aluminosilicate. Sodium carbonate assists the alkaline source, fills the micropores of CSH gel, improves the density of the system, and generates a calcium phosphate coating on the surface of calcium hydroxide to prepare modified calcium hydroxide, which is stably dispersed in the system. Furthermore, phosphate ions can form phosphate precipitates with extremely low solubility, reducing the leaching of metal ions, activating the reaction of aluminosilicate, improving the bonding performance between various components in the system, improving compressive strength, and effectively reducing the amount of binder used. This green and environmentally friendly approach protects the mine ecology and reduces carbon emissions during the mine waste treatment process.

[0032] A tannic acid complex component is also added to the adhesive, wherein the tannic acid contains phenolic hydroxyl groups, which interact with free C... a2+ Na + Electrostatic adsorption is formed, accelerating the process of Ca. 2+ The zinc ions in zinc sulfate can migrate to the surface of slag, increasing the formation efficiency of CSH. 3+ It dissolves and promotes the formation of gels with silica and calcium ions, thereby improving bonding performance and durability;

[0033] The phenolic hydroxyl groups of tannic acid dissociate moderately in a weakly alkaline environment provided by alkaline additives, thereby exhibiting good metal adsorption properties and forming stable chelates with heavy metal ions. This synergistic effect enhances mechanical strength and fixes metal particles, making the prepared adhesive a core requirement for applications such as mine slag adhesives and heavy metal pollution remediation. Detailed Implementation

[0034] The present application will be further described in detail below with reference to the embodiments:

[0035] Raw material description: All raw materials in the examples are commercially available; the retarder is citric acid (CAS No.: 77-92-9). Example 1

[0036] Preparation of modified calcium hydroxide:

[0037] Calcium hydroxide powder was passed through a 100-mesh sieve. 5.26 kg of the sieved calcium hydroxide was mixed with 100 kg of deionized water and magnetically dispersed to obtain a calcium hydroxide solution. 0.74 kg of sodium polymorphophosphate (CAS No.: 68915-31-1) was mixed with 90 kg of deionized water to obtain a sodium polymorphophosphate dispersion. The sodium polymorphophosphate dispersion was added to the calcium hydroxide solution and stirred at 400 rpm for 2 hours. Then, the mixture was centrifuged at 2000 rpm to remove the supernatant. After washing with deionized water, the mixture was freeze-dried for 24 hours to obtain modified calcium hydroxide.

[0038] Preparation of alkaline additives:

[0039] 3.64 kg of modified calcium hydroxide and 2.61 kg of sodium carbonate were added to a mixer and mixed at 20 rpm for 40 min. Then, 1.75 kg of sodium silicate solid powder was added to the mixer and mixed at 25 rpm for 20 min to obtain an alkaline additive.

[0040] Preparation of tannic acid gel:

[0041] Tris(hydroxymethyl)aminomethane (CAS No.: 77-86-1) was mixed with deionized water at a mass ratio of 1:4 to obtain a tris(hydroxymethyl)aminomethane solution. 40 kg of the tris(hydroxymethyl)aminomethane solution was mixed with 8.08 kg of tannic acid (CAS No.: 1401-55-4) to obtain a tannic acid solution. 1.92 kg of lipoic acid (CAS No.: 62-46-4) was added to the tannic acid solution and stirred until homogeneous. The mixture was heated to 70°C while maintaining stirring until it became viscous. The mixture was then poured into a polytetrafluoroethylene mold, frozen at -20°C, and thawed at 25°C to obtain a tannic acid gel.

[0042] Preparation of tannic acid complex components:

[0043] 6.96 kg of tannic acid gel was mixed with 138.5 kg of methylpyrrolidone (CAS No.: 872-50-4) to obtain a gel solution. 1.04 kg of silica was ground and added to the gel solution. After stirring evenly, the mixture was ultrasonically dispersed and dried at 150°C for 12 h to obtain the tannic acid composite component.

[0044] Preparation of adhesives:

[0045] Mix 65 kg of slag, 8 kg of calcium aluminate cement, 3 kg of mineral powder, 2 kg of phosphate powder, 2 kg of alkaline additive, 1.3 kg of tannic acid composite component, and 0.4 kg of retarder, then add the mixture to a mixer and mix at 20 rpm for 40 minutes to obtain a mixed aggregate. Transfer the mixed aggregate to a disperser and maintain a stirring speed of 1500 rpm. Add 0.8 kg of sodium hydroxide and 5 kg of water, and stir for 5 minutes. Then add 1.5 kg of water glass and 13 kg of water, and continue stirring for 10 minutes to obtain a slurry. After standing for 10 minutes, obtain the binder. Example 2

[0046] Preparation of modified calcium hydroxide:

[0047] Calcium hydroxide powder was passed through a 100-mesh sieve. 5.08 kg of the sieved calcium hydroxide was mixed with 100 kg of deionized water and magnetically dispersed to obtain a calcium hydroxide solution. 0.92 kg of sodium polyphosphate was mixed with 90 kg of deionized water to obtain a sodium polyphosphate dispersion. The sodium polyphosphate dispersion was added to the calcium hydroxide solution and stirred at 400 rpm for 2 hours. Then, the mixture was centrifuged at 2000 rpm to remove the supernatant. After washing with deionized water, the mixture was freeze-dried for 24 hours to obtain modified calcium hydroxide.

[0048] Preparation of alkaline additives:

[0049] 4.15 kg of modified calcium hydroxide and 2.31 kg of sodium carbonate were added to a mixer and mixed at 20 rpm for 40 min. Then, 1.54 kg of sodium silicate solid powder was added to the mixer and mixed at 25 rpm for 20 min to obtain an alkaline additive.

[0050] Preparation of tannic acid gel:

[0051] Tris(hydroxymethyl)aminomethane and deionized water were mixed at a mass ratio of 1:4 to obtain a tris(hydroxymethyl)aminomethane solution. 40 kg of the tris(hydroxymethyl)aminomethane solution was mixed with 8.28 kg of tannic acid to obtain a tannic acid solution. 1.72 kg of lipoic acid was added to the tannic acid solution and stirred until homogeneous. The mixture was heated to 70°C while maintaining stirring until it became viscous. The mixture was then poured into a polytetrafluoroethylene mold, frozen at -20°C, and thawed at 25°C to obtain a tannic acid gel.

[0052] Preparation of tannic acid complex components:

[0053] 6.72 kg of tannic acid gel was mixed with 138.5 kg of methylpyrrolidone to obtain a gel solution. 1.28 kg of silica was ground and added to the gel solution. After stirring evenly, the mixture was ultrasonically dispersed and dried at 150°C for 12 h to obtain the tannic acid composite component.

[0054] Preparation of adhesives:

[0055] Mix 70 kg of slag, 12 kg of calcium aluminate cement, 5 kg of mineral powder, 3 kg of phosphate powder, 5 kg of alkaline additives, 3.75 kg of tannic acid composite components, and 0.8 kg of retarder, then add the mixture to a mixer and mix at 20 rpm for 40 minutes to obtain a mixed aggregate. Transfer the mixed aggregate to a disperser and maintain a stirring speed of 1500 rpm. Add 1.2 kg of sodium hydroxide and 10 kg of water and stir for 5 minutes. Then add 2.5 kg of water glass and 8 kg of water and continue stirring for 10 minutes to obtain a slurry. After standing for 10 minutes, obtain the binder. Example 3

[0056] Preparation of modified calcium hydroxide:

[0057] Calcium hydroxide powder was passed through a 100-mesh sieve. 5.17 kg of the sieved calcium hydroxide was mixed with 100 kg of deionized water and magnetically dispersed to obtain a calcium hydroxide solution. 0.83 kg of sodium polyphosphate was mixed with 90 kg of deionized water to obtain a sodium polyphosphate dispersion. The sodium polyphosphate dispersion was added to the calcium hydroxide solution and stirred at 400 rpm for 2 hours. Then, the mixture was centrifuged at 2000 rpm to remove the supernatant. After washing with deionized water, the mixture was freeze-dried for 24 hours to obtain modified calcium hydroxide.

[0058] Preparation of alkaline additives:

[0059] 3.91 kg of modified calcium hydroxide and 2.45 kg of sodium carbonate were added to a mixer and mixed at 20 rpm for 40 min. Then, 1.64 kg of sodium silicate solid powder was added to the mixer and mixed at 25 rpm for 20 min to obtain an alkaline additive.

[0060] Preparation of tannic acid gel:

[0061] Tris(hydroxymethyl)aminomethane and deionized water were mixed at a mass ratio of 1:4 to obtain a tris(hydroxymethyl)aminomethane solution. 40 kg of the tris(hydroxymethyl)aminomethane solution was mixed with 8.18 kg of tannic acid to obtain a tannic acid solution. 1.82 kg of lipoic acid was added to the tannic acid solution and stirred until homogeneous. The mixture was heated to 70°C while maintaining stirring until it became viscous. The mixture was then poured into a polytetrafluoroethylene mold, frozen at -20°C, and thawed at 25°C to obtain a tannic acid gel.

[0062] Preparation of tannic acid complex components:

[0063] 6.84 kg of tannic acid gel was mixed with 138.5 kg of methylpyrrolidone to obtain a gel solution. 1.16 kg of silica was ground and added to the gel solution. After stirring evenly, the mixture was ultrasonically dispersed and dried at 150°C for 12 h to obtain the tannic acid composite component.

[0064] Preparation of adhesives:

[0065] Mix 67 kg of slag, 10 kg of calcium aluminate cement, 4 kg of mineral powder, 2.5 kg of phosphate powder, 4 kg of alkaline additives, 2.8 kg of tannic acid composite components, and 0.7 kg of retarder, then add the mixture to a mixer and mix at 20 rpm for 40 minutes to obtain a mixed aggregate. Transfer the mixed aggregate to a disperser and maintain a stirring speed of 1500 rpm. Add 1.0 kg of sodium hydroxide and 8 kg of water, and stir for 5 minutes. Then add 2.0 kg of water glass and 10 kg of water, and continue stirring for 10 minutes to obtain a slurry. After standing for 10 minutes, obtain the binder. Example 4

[0066] Example 4 is based on Example 3. In Example 4, when preparing modified calcium hydroxide, 5.45 kg of calcium hydroxide and 0.55 kg of sodium polyphosphate were used. Example 5

[0067] Example 5 is based on Example 3. In Example 5, when preparing modified calcium hydroxide, 4.92 kg of calcium hydroxide and 1.08 kg of sodium polyphosphate were used. Example 6

[0068] Example 6 is based on Example 3. In Example 6, when preparing the alkaline additive, 3.17 kg of modified calcium hydroxide, 2.89 kg of sodium carbonate, and 1.94 kg of sodium silicate were used. Example 7

[0069] Example 7 is based on Example 3. In Example 7, when preparing the alkaline additive, 4.46 kg of modified calcium hydroxide, 2.12 kg of sodium carbonate, and 1.42 kg of sodium silicate were used. Example 8

[0070] Example 8 is based on Example 3. In Example 8, 7.87g of tannic acid and 2.13g of thioctic acid were used when preparing the tannic acid gel. Example 9

[0071] Example 9 is based on Example 3. In Example 9, 8.41 kg of tannic acid and 1.59 kg of thioctic acid were used in the preparation of tannic acid gel. Example 10

[0072] Example 10 is based on Example 3. In Example 10, when preparing the tannic acid composite component, 7.27 kg of tannic acid gel and 0.73 kg of silica were used. Example 11

[0073] Example 11 is based on Example 3. In Example 11, when preparing the tannic acid composite component, 6.45 kg of tannic acid gel and 1.55 kg of silica were used. Example 12

[0074] Example 12 is based on Example 3, but without the addition of silica to the tannic acid complex in Example 12. Example 13

[0075] Example 13 is based on Example 3, except that the tannic acid gel was replaced with ordinary tannic acid during the preparation of the tannic acid complex in Example 13. Example 14

[0076] Example 14 is based on Example 3, and the amount of tannic acid composite component used in the adhesive of Example 14 is 2 kg. Example 15

[0077] Example 15 is based on Example 3, and the amount of tannic acid component used in the adhesive of Example 15 is 3.6 kg.

[0078] Comparative Example 1

[0079] Comparative Example 1 is based on Example 3, except that the modified calcium hydroxide with alkaline additive in Comparative Example 1 is replaced with an equal amount of ordinary calcium hydroxide.

[0080] Comparative Example 2

[0081] Comparative Example 2 is based on Example 3, but sodium silicate was not added to the alkaline additive in Comparative Example 2.

[0082] Comparative Example 3

[0083] Comparative Example 3 is based on Example 3, but no sodium carbonate was added to the alkaline additive in Comparative Example 3.

[0084] Performance testing

[0085] The following performance tests were performed on the samples of Examples 1-15 and Comparative Examples 1-3:

[0086] (1) Curing rate

[0087] Using GB / T 1346-2011 and GB / T 50081-2019 as testing references, the initial setting time and compressive strength of the samples after 7 days of curing were tested. The curing conditions were as follows: the samples were prepared into cubic blocks of 150mm×150mm×150mm and cured under standard conditions (temperature 20±2℃, humidity ≥95%) for 7 days; each sample was tested 3 times and the average value was taken. The test results were recorded in Table 1.

[0088] (2) Impermeability

[0089] Using GB / T 50082-2009 as the testing reference, a permeability tester was used to apply water pressure to a 175mm×185mm×150mm frustum specimen, and the permeability coefficient was calculated. Each specimen was tested three times, and the average value was taken. The test results were recorded in Table 1.

[0090] (3) Corrosion resistance

[0091] For each sample, several 40mm×40mm×160mm prism blocks were prepared. After curing for 28 days, the mass of the sample was measured. Then, the samples were immersed in 5% H2SO4 solution, 10% NaOH solution, and artificial seawater, respectively. After 28 days, the samples were taken out and their mass was tested. The mass loss rate was calculated. Each sample was tested 3 times and the average value was taken. The test results were recorded in Table 1.

[0092] (4) Heavy metal fixation rate

[0093] Referring to HJ / T 299-2007, the solid was crushed to a particle size of <10mm, and the extractant (sulfuric acid-nitric acid mixture) was mixed at a liquid-solid ratio of 10:1. After shaking and extraction, the concentrations of As and Pb in the leachate were determined by ICP-MS. Each sample was tested 3 times, and the average value was taken. The test results were filled in Table 1.

[0094] Table 1 Performance test results of Examples 1-15 and Comparative Examples 1-3

[0095]

[0096] As shown in Table 1, the initial setting time of the samples in Examples 1-3 was all 26 min or less, and the 7-day compressive strength was all 47.5 N / mm² or higher, indicating that the adhesive prepared in this application has good bonding and fixing properties. The permeability coefficient of Examples 1-3 was all 9.0 × 10⁻⁶. -12 The following results demonstrate that the adhesive prepared in this application has good impermeability; the mass loss rate of Examples 1-3 after acid, alkali, and seawater erosion is all 1.45% or less, indicating that this application has good chemical corrosion resistance; the As leaching rate and Pb leaching rate of Examples 1-3 are all 0.08 mg / dm³ or less, indicating that the adhesive prepared in this application has good heavy metal fixation rate.

[0097] In Examples 4 and 5, the mass ratio of calcium hydroxide to sodium polyphosphate during the preparation of modified calcium hydroxide was not within the range specified in this application. When the content of sodium polyphosphate was too low, calcium hydroxide could not be evenly dispersed by the electrostatic effect of insufficient sodium polyphosphate, resulting in agglomeration. Some calcium aluminate cements hydrated too quickly in the early stage, while others could not be fully hydrated, leading to a decrease in bonding strength and a loose structure. This resulted in excessively high porosity inside the binder, allowing metal ions to leach into the environment. When the content of sodium polyphosphate was too high, an excessively thick adsorption layer would form on the surface of the calcium hydroxide particles, isolating calcium hydroxide from contact with slag and calcium aluminate cement, and inhibiting the growth of hydration products. This reduced the bonding performance, and heavy metal ions in the slag were directly exposed to the external environment. Therefore, the performance of Examples 4 and 5 was reduced.

[0098] In Examples 6 and 7, the mass ratios of modified calcium hydroxide, sodium carbonate, and sodium silicate during the preparation of the alkaline additives were not within the range specified in this application. When the content of modified calcium hydroxide was too low, the pH value of the system decreased, making it difficult to further activate the aluminosilicate reaction, resulting in a loose structure of the CSH gel product, decreased binding performance, and decreased metal ion coating performance. When the content of modified calcium hydroxide was too high, the pH value of the system was too high, causing the self-polymerization of SiO3²⁻ in sodium silicate to be too fast, while the efficiency of reacting with Ca²⁺ to form CSH gel decreased, the uniformity of the system decreased, and the later drying shrinkage rate was too high, resulting in decreased compressive strength and decreased coating performance for metal ions. At the same time, an excessively high pH value would cause the phenolic hydroxyl groups of tannic acid to decompose, affecting the overall performance of the system. Therefore, the performance of Examples 6 and 7 was reduced.

[0099] In Examples 8 and 9, the mass ratio of tannic acid to lipoic acid during the preparation of tannic acid gels was not within the range specified in this application. When the content of tannic acid was too low, the phenolic hydroxyl groups of tannic acid were extensively combined with the thiol and carboxyl groups of lipoic acid, forming an extremely high cross-linking density. The resulting gel network was too dense, the porosity decreased, and the diffusion of metal ions into the gel interior was hindered. When the content of tannic acid was too high, the excess tannic acid was difficult to fully cross-link, and a stable three-dimensional network structure could not be formed. The adsorption performance for metal ions was weakened, and the binding performance also decreased.

[0100] In Examples 10 and 11, the mass ratio between tannic acid gel and silica during the preparation of the tannic acid composite component was not within the range specified in this application. When the silica content was too low, the skeleton of the tannic acid composite component could not support the network structure, and the gel network would collapse during drying or water absorption, making it difficult to promote the diffusion of metal ions into the gel. When the silica content was too high, it would accumulate in the gel network, causing agglomeration, affecting the uniformity of the system, and blocking the originally regular three-dimensional pores. This would reduce the binding rate of metal ions to active sites and decrease the adsorption performance.

[0101] In Example 12, no silica was added to the tannic acid complex. Silica, as a rigid framework and dispersion medium, plays a role in preventing gel aggregation and enhancing the mechanical strength of the system. Without the addition of silica, the tannic acid gel aggregated, which affected the adsorption effect on metal ions and reduced the mechanical properties.

[0102] In Example 13, when preparing the tannic acid complex, the tannic acid gel was replaced with ordinary tannic acid. Ordinary tannic acid has no cross-linking structure, and a large number of active sites are lost with the tannic acid molecules. The tannic acid that is not lost is prone to agglomeration. At the same time, silica cannot be fixed through the gel network and agglomerates in the system, which reduces the overall mechanical strength and metal ion fixation performance of the system.

[0103] In Examples 14 and 15, the mass ratio between the alkaline additive and the tannic acid composite component during adhesive preparation was not within the range specified in this application. When the amount of tannic acid component added was too small, the excess alkaline component in the alkaline additive would react excessively with the small amount of tannic acid in the system, causing the tannic acid molecular chains to break, reducing the stability of the system, and also reducing the adsorption performance for metal ions. When the amount of tannic acid component added was too large, the alkaline additive could not completely neutralize the phenolic hydroxyl and carboxyl groups of tannic acid. Strong hydrogen bonding forces existed between tannic acid molecules, causing the gel to agglomerate. Furthermore, silica was difficult to further disperse in the agglomerated gel and dispersed on the gel surface, resulting in decreased dispersibility and agglomeration. This affected the overall mechanical properties of the system and the adsorption performance for metal ions.

[0104] In Comparative Example 1, the modified calcium hydroxide with alkaline additives was replaced with ordinary calcium hydroxide. Ordinary calcium hydroxide agglomerates and disrupts the continuous network of tannic acid gel, resulting in voids inside the gel system, decreased mechanical strength, decreased binding performance, and decreased adsorption performance of metal ions.

[0105] In Comparative Example 2, sodium silicate was not added as an alkaline additive. The strong alkalinity of calcium hydroxide could not be buffered, resulting in an excessively high pH value in the system. The phenolic groups of tannic acid were oxidized, and the cross-linking and adsorption properties decreased significantly, as did the binding properties between systems.

[0106] In Comparative Example 3, no sodium carbonate was added as an alkaline additive, resulting in an excessively high pH value in the system. Furthermore, the lack of CO3²⁻ from sodium carbonate made it difficult for tannic acid molecules, calcium hydroxide particles, and silica particles to combine and form a tight three-dimensional network, leading to decreased stability.

[0107] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.

Claims

1. An adhesive for bonding mine slag, characterized in that: It includes 65-70 parts slag, 8-12 parts calcium aluminate cement, 3-5 parts mineral powder, 2-3 parts phosphorus powder, 1.5-2.5 parts water glass, 0.8-1.2 parts sodium hydroxide, 0.6-0.8 parts retarder, and 2-5 parts alkaline additives; The alkaline additive includes modified calcium hydroxide, sodium silicate, and sodium carbonate, wherein the modified calcium hydroxide includes calcium hydroxide and sodium polymethphosphate. The adhesive also includes a tannic acid composite component, which comprises tannic acid gel and silica, and the tannic acid gel raw material comprises tannic acid and zinc sulfate. The tannic acid gel was prepared using the following method: Tris(hydroxymethyl)aminomethane was mixed with water to obtain a tris(hydroxymethyl)aminomethane solution; the tris(hydroxymethyl)aminomethane solution was mixed with tannic acid to obtain a tannic acid solution; zinc sulfate was added to the tannic acid solution and stirred, and the temperature was raised until the system became viscous while maintaining stirring; after freezing and thawing, a tannic acid gel was obtained. The tannic acid composite component was prepared by the following method: Tannic acid gel was mixed with methylpyrrolidone to obtain a gel solution. Silica was added to the gel solution, ultrasonically dispersed, and then dried to obtain the tannic acid composite component.

2. The adhesive for bonding mine slag according to claim 1, characterized in that: The modified calcium hydroxide was prepared by the following method: Calcium hydroxide was mixed and dispersed with water to obtain a calcium hydroxide solution. Sodium polyphosphate was mixed with water to obtain a sodium polyphosphate dispersion. The sodium polyphosphate dispersion was added to the calcium hydroxide solution and stirred. Then, the mixture was centrifuged, the supernatant was removed, and after washing, it was freeze-dried to obtain modified calcium hydroxide.

3. The adhesive for bonding mine slag according to claim 2, characterized in that: The mass ratio of calcium hydroxide to sodium polyphosphate is 1:(0.14-0.18).

4. The adhesive for bonding mine slag according to claim 2, characterized in that: The mass ratio of the modified calcium hydroxide, sodium carbonate and sodium silicate is (1.4-1.8):1:0.

67.

5. The adhesive for bonding mine slag according to claim 1, characterized in that: The mass ratio of tannic acid to zinc sulfate is (4.6-4.9):

1.

6. The adhesive for bonding mine slag according to claim 1, characterized in that: The mass ratio of the tannic acid gel to silica is 1:(0.15-0.19).

7. The adhesive for bonding mine slag according to claim 1, characterized in that: The mass ratio between the alkaline additive and the tannic acid composite component is 1:(0.65-0.75).

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