A cementing material suitable for high-sulfur tailings backfill and a preparation method thereof

Abstract

The present application relates to the technical field of mine filling material, and particularly relates to a cementing material suitable for high-sulfur tailings and a preparation method thereof. In order to reduce the filling cost and realize low-cost green filling mining, the present application uses high-sulfur tailings and gobi aggregate as mixed filling aggregate, and uses quicklime, silica fume, desulfurization gypsum and slag powder as cementing material. The quicklime, silica fume and desulfurization gypsum composite excite the potential cementing performance of the filling material, and the NiCs-LDH@CuO is introduced to further promote the excitation performance of the quicklime, silica fume and desulfurization gypsum composite to excite the high-sulfur tailings filling body.

Description

Technical Field

[0001] This invention relates to the field of mine backfill materials technology, specifically to a cementitious material suitable for high-sulfur tailings and its preparation method. Background Technology

[0002] High-sulfur tailings are solid wastes with high sulfur content generated during the beneficiation process of metal mines (such as copper, gold, lead-zinc, etc.). They are often accompanied by harmful heavy metals such as lead (Pb), zinc (Zn), arsenic (As), and cadmium (Cd), which are easily leached under acidic conditions, polluting soil and groundwater. High-sulfur tailings mostly have a particle size of <0.075mm, a large specific surface area, are prone to dust generation, have poor permeability, and extremely low strength in their natural state, making them unsuitable for direct use in engineering backfilling.

[0003] Traditional tailings disposal methods occupy land and pose a risk of dam failure. Various countries have mandated the "harmless backfilling" of mine tailings. Backfilling technology can simultaneously address safety and pollution issues, making the solidification treatment of high-sulfur tailings a necessity. Mine backfilling technology is a crucial component of green mining of mineral resources, and the solidification treatment of high-sulfur tailings has always been a technical challenge in the industry. Traditional cementitious materials (such as ordinary silicate cement) present many problems in high-sulfur environments, such as strength degradation due to sulfide erosion, low solidification efficiency, environmental risks, and limitations of the activator system.

[0004] Currently, mines primarily use mixed aggregates formed from high-sulfur tailings and Gobi sediment, with cementing materials consisting of M37.5 cement and slag powder; the backfill slurry concentration is below 80%, typically around 77%. However, the later-stage strength of cemented backfill containing high-sulfur tailings is affected by sulfate erosion. Therefore, exploring the mechanical properties of high-sulfur tailings backfill to reduce the overall cost of composite backfill materials while meeting the long-term strength requirements for mine backfill stability is an urgent issue for mines. To reduce backfill costs and achieve low-cost green backfill mining, this invention uses high-sulfur tailings and Gobi sediment as mixed backfill aggregates, and quicklime, silica fume, desulfurized gypsum, cement, and slag powder as cementing materials. The combination of quicklime, silica fume, and desulfurized gypsum can activate the mixture of cement and slag powder, improving the strength of the backfill. Simultaneously, this invention also introduces NiCs-LDH@CuO, a composite catalyst that can promote the activation of the composite properties of quicklime, silica fume, and desulfurized gypsum. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a cementitious material and preparation method for high-sulfur tailings backfill. This is achieved through the following technical solutions:

[0006] S1: Copper mesh processing: Use a mesh area of ​​0.8-1.5cm². 2The copper mesh is placed in 5-10 ml of 1M hydrochloric acid and sonicated for 15-20 minutes. Afterward, the copper mesh is removed and placed in 5-10 ml of ethanol, and sonicated again for 5-10 minutes. Then, the copper mesh is removed and rinsed 2-3 times with deionized water. After cleaning, the copper mesh is sealed with deionized water. Soaking the copper mesh in hydrochloric acid removes irregular CuO and Cu2(OH)2CO3 impurities from its surface, while soaking it in ethanol treats any acid adhering to its surface.

[0007] S2: Preparation of CuO: Weigh 1.2-2.3g of KOH and 0.2-0.5g of K2S2O8, add 10-30ml of deionized water, and after the reagents are completely dissolved, put the treated copper mesh into the solution and keep the copper mesh completely immersed for 30-50 minutes. After taking out the copper mesh, put it into an oven and heat it at 120-200℃ for 30-50 minutes.

[0008] S3: Preparation of NiCs-LDH@CuO: Weigh 0.02-0.05g of NiCl2, 0.10-0.25g of CsCl, and 0.2-0.5g of hexamethylenetetramine, add 30-50ml of deionized water, place the copper sheet from step S2 into the solution, and then transfer it to a muffle furnace. Heat at 100-150℃ for 3-6 hours. After the muffle furnace cools, remove the sheet and dry it. This sheet is NiRb-LDH@CuO. Finally, use a rotary kneader to pulverize the sheet to obtain NiCs-LDH@CuO powder. NiCs-LDH@CuO, as a composite catalyst, can act as a highly efficient active activator in the quicklime-silica fume-desulfurized gypsum composite activation system, significantly improving the early hydration efficiency of cementitious materials. Its layered structure (LDH) regulates Ca through ion exchange. 2+ SO4 2- The release kinetics, and the semiconductor properties of CuO nanoparticles promote electron transfer, accelerating the hydrolysis of quicklime (CaO) and the dissolution of silica fume. This composite material can synergistically optimize the formation of ettringite (AFt) with desulfurized gypsum, enhance the density of the interfacial transition zone, and reduce the volume instability problems caused by traditional strong base activators.

[0009] S4: Referring to the "GB / T 51003-2014" Technical Specification for the Application of Mineral Admixtures, weigh out 534.6-945.0g of high-sulfur tailings, 891.0-1323.0g of Gobi aggregate, 141.75-222.75g of slag powder, 18.9-29.7g of quicklime, 9.45-14.85g of silica fume, 18.9-29.7g of desulfurized gypsum, 2.32-4.74g of NiCs-LDH@CuO powder prepared by S3, and 621-693mL of water. Place these into a cement mortar mixer and stir continuously for 5-8 minutes to ensure thorough and uniform mixing of the filling aggregate and cementitious material. Pour the slurry manually using a slurry ladle. To prevent sedimentation, stir continuously during pouring, following the direction of slurry rotation. Quickly remove the slurry and pour it into the standard mold. The filling slurry was evenly poured into three molds, extending 2 mm above the mold. After pouring, the molds were placed on a vibrating table for 30 seconds to compact. Excess slurry was scraped off from both sides of the mold with a trowel and the surface was gently smoothed. Demolding was performed 48 hours after pouring, separating the filling sample from the mold. An air pump was used to slowly remove the sample from the bottom of the mold to ensure its integrity. After demolding, the sample was placed in a standard constant temperature and humidity curing chamber at 20±2℃ and relative humidity greater than 90% for curing until the specified curing age was reached. Quicklime, silica fume, and desulfurized gypsum were mixed evenly in a certain proportion as a composite activator to activate the potential activity of the filling material and improve its mechanical properties and durability. Quicklime provides an alkaline environment, disrupting the silica-alumina glass structure and promoting dissolution; highly active SiO2 reacts with Ca(OH)2 to form CSH gel, improving the density and mechanical strength of the filling; desulfurized gypsum provides SO42-. 2- The silica fume reacts with the aluminum phase to form ettringite (AFt), compensating for shrinkage and enhancing early strength. NiCs-LDH in NiCs-LDH@CuO provides alkaline sites, promoting the destruction of the silica-alumina glass structure by quicklime, and also promoting the reaction of highly reactive SiO2 in silica fume with Ca(OH)2 to form CSH gel. Furthermore, silica fume can exert a "physical filling effect," improving the structural density of high-sulfur tailings backfill from a microscopic perspective; and highly reactive SiO2 generates silicate substances in an alkaline environment, with silicate compounds exhibiting superior performance compared to sulfate compounds.

[0010] Preferably: In step S1 of the present invention, the area is 0.8 cm². 2 The copper mesh was placed in 5 ml of 1M hydrochloric acid and sonicated in an ultrasonic instrument for 15 minutes. Then the copper mesh was removed and placed in 5 ml of ethanol and sonicated in an ultrasonic instrument for another 5 minutes. The copper mesh was then removed and rinsed twice with deionized water. After cleaning, the copper mesh was sealed with deionized water.

[0011] Preferably: In step S1 of the present invention, the area is 1.5 cm². 2 The copper mesh was placed in 10 ml of 1M hydrochloric acid and sonicated in an ultrasonic instrument for 20 minutes. Then the copper mesh was removed and placed in 10 ml of ethanol and sonicated in an ultrasonic instrument for another 10 minutes. The copper mesh was then removed and rinsed three times with deionized water. After cleaning, the copper mesh was sealed with deionized water.

[0012] Preferably: In step S2 of the present invention, 1.2g of KOH and 0.2g of K2S2O8 are weighed and added to 10ml of deionized water. After the drugs are completely dissolved, the treated copper mesh is placed in the solution and kept completely immersed for 30 minutes. After the copper mesh is removed, it is placed in an oven and heated at 120°C for 30 minutes.

[0013] Preferably: In step S3 of the present invention, 0.02g of NiCl2, 0.10g of CsCl and 0.2g of hexamethylenetetramine are weighed, 30ml of deionized water is added, the copper sheet from step S2 is placed in, and then transferred to a muffle furnace and heated at 120°C for 5 hours. After the muffle furnace cools down, the obtained sheet is taken out and dried. This sheet is NiRb-LDH@CuO. Finally, the sheet is pulverized using a rotary mixer to obtain NiCs-LDH@CuO powder.

[0014] Preferably: In step S3 of the present invention, 0.05g of NiCl2, 0.25g of CsCl and 0.5g of hexamethylenetetramine are weighed, 50ml of deionized water is added, the copper sheet from step S2 is placed in, and then transferred to a muffle furnace and heated at 120°C for 5 hours. After the muffle furnace cools down, the obtained sheet is taken out and dried. This sheet is NiRb-LDH@CuO. Finally, the sheet is pulverized using a rotary mixer to obtain NiCs-LDH@CuO powder.

[0015] Preferably, in step S4 of this invention, referring to the "GB / T 51003-2014" technical specification for the application of mineral admixtures, 534.6g of high-sulfur tailings, 891.0g of Gobi aggregate, 222.7g of slag powder, 29.70g of quicklime, 14.85g of silica fume, 29.70g of desulfurized gypsum, 2.32g of NiCs-LDH@CuO powder prepared in S3, and 621mL of water are weighed and placed in a cement mortar mixer and continuously stirred for 5 minutes to ensure that the filling aggregate and cementitious material are fully and evenly mixed. The slurry is poured manually using a slurry ladle. To prevent sedimentation of the slurry, it is stirred while pouring, following the direction of slurry rotation. The slurry is then quickly removed and poured into the standard mold. The filling grout is poured evenly into three molds, extending 2 mm above the mold. After pouring, the mold is placed on a vibrating table for 30 seconds to compact. Excess grout is scraped off from both sides of the mold with a trowel and the surface is gently smoothed. Demolding is performed 48 hours after pouring, separating the filling sample from the mold. An air pump is used to slowly remove the sample from the bottom of the mold to ensure its integrity. After demolding, the sample is placed in a standard constant temperature and humidity curing chamber at 20±2℃ and relative humidity greater than 90% until the specified curing age is reached.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. Quicklime, silica fume, and desulfurized gypsum are compounded in a certain proportion to act as a composite activator to stimulate the potential activity of the filling material and improve its mechanical properties and durability.

[0018] 2. Quicklime provides an alkaline environment, which disrupts the structure of the aluminosilicate glass and promotes dissolution.

[0019] 3. The highly reactive SiO2 in silica fume reacts with Ca(OH)2 to form CSH gel, which improves the density and mechanical strength of the filling body, and the long-term strength does not show obvious deterioration, which helps to ensure the overall stability of the filling area.

[0020] 4. Desulfurized gypsum provides SO4 2- It reacts with the aluminum phase to form ettringite (AFt), which compensates for shrinkage and enhances early strength.

[0021] 5. This invention is simple to operate, has low production costs, and is conducive to mass production.

[0022] 6. NiCs-LDH@CuO, as a composite catalyst, can serve as a highly efficient activator in the quicklime-silica fume-desulfurized gypsum composite activation system, significantly improving the early hydration efficiency of cementitious materials. Its layered structure (LDH) regulates Ca through ion exchange. 2+ SO4 2- The release kinetics, and the semiconductor properties of CuO nanoparticles promote electron transfer, accelerating the hydrolysis of quicklime (CaO) and the dissolution of silica fume. This composite material can synergistically optimize the formation of ettringite (AFt) with desulfurized gypsum, enhance the density of the interfacial transition zone, and reduce the volume instability problems caused by traditional strong base activators.

[0023] 7. As a composite catalyst, NiCs-LDH@CuO can significantly increase the amount of high-sulfur tailings added while maintaining the same performance of the high-sulfur tailings backfill, thereby significantly improving the tailings utilization rate and greatly reducing the backfilling cost. Attached Figure Description

[0024] Figure 1This is a scanning electron microscope image of NiCs-LDH@CuO prepared in Example 1 of the present invention.

[0025] Figure 2 The microstructure of the high-sulfur tailings backfill prepared in Example 1 of this invention is shown.

[0026] Figure 3 The image shows the XRD pattern of silica fume. Detailed Implementation

[0027] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0028] The chemical composition and particle size distribution of some of the raw materials in this application are as follows:

[0029] Table 1 Chemical composition of slag powder

[0030] content / % 43.69 26.94 10.04 7.12 0.51 2.82 composition MnO SO3 Na2O K2O other content / % 0.78 2.23 0.97 0.81 4.09

[0031] Table 2 Chemical composition of quicklime

[0032] content / % 85.20 1.03 0.65 0.99 0.72 0.36 11.05

[0033] Table 3 Chemical composition of desulfurized gypsum

[0034] content / % 42.72 45.79 0.79 1.78 0.30 0.88 0.62 7.12

[0035] Table 4 Chemical composition of high-sulfur tailings

[0036] content / % 2.47 25.09 9.23 2.08 22.33 0.047 0.145 composition <![CDATA[P2O5]]> <![CDATA[K2O]]> <![CDATA[Na2O]]> <![CDATA[SO3]]> other content / % 0.025 1.35 0.59 31.89 4.753

[0037] Table 5. Particle size distribution of Gobi aggregates

[0038] -0.020 3.96 3.96 0.020-0.035 7.95 11.91 0.035-0.075 5.94 17.85 0.075-1 21.27 39.12 1-5 22.58 61.70 5-10 14.11 75.81 10-15 12.80 88.61 15-20 9.49 98.09 20-25 1.91 100

[0039] Example 1:

[0040] S1: Copper mesh processing: Take an area of ​​0.8cm² 2The copper mesh was placed in 5 ml of 1M hydrochloric acid and sonicated for 15 minutes. Then, the copper mesh was removed and placed in 5 ml of ethanol, and sonicated for another 5 minutes. Afterward, the copper mesh was removed and rinsed twice with deionized water. Finally, the copper mesh was sealed with deionized water. Soaking the copper mesh in hydrochloric acid was to remove irregular CuO and Cu2(OH)2CO3 impurities from its surface, while soaking it in ethanol was to treat the acid adhering to its surface.

[0041] S2: Preparation of CuO: Weigh 1.2g of KOH and 0.2g of K2S2O8, add 10ml of deionized water, and after the reagents are completely dissolved, put the treated copper mesh into the solution and keep the copper mesh completely immersed for 30 minutes. After taking out the copper mesh, put it into an oven and heat it at 120℃ for 30 minutes.

[0042] S3: Preparation of NiCs-LDH@CuO: Weigh 0.02g of NiCl2, 0.10g of CsCl, and 0.2g of hexamethylenetetramine, add 30ml of deionized water, place the copper sheet from step S2 into the solution, and then transfer it to a muffle furnace. Heat at 120℃ for 5 hours. After the muffle furnace cools, remove the sheet and dry it. This sheet is NiRb-LDH@CuO. Finally, use a rotary kneader to pulverize the sheet to obtain NiCs-LDH@CuO powder. NiCs-LDH@CuO, as a composite catalyst, can act as a highly efficient active activator in the quicklime-silica fume-desulfurized gypsum composite activation system, significantly improving the early hydration efficiency of cementitious materials. Its layered structure (LDH) regulates Ca through ion exchange. 2+ SO4 2- The release kinetics, and the semiconductor properties of CuO nanoparticles promote electron transfer, accelerating the hydrolysis of quicklime (CaO) and the dissolution of silica fume. This composite material can synergistically optimize the formation of ettringite (AFt) with desulfurized gypsum, enhance the density of the interfacial transition zone, and reduce the volume instability problems caused by traditional strong base activators.

[0043] S4: Referring to the "GB / T 51003-2014" Technical Specification for the Application of Mineral Admixtures, weigh out 723.4g of high-sulfur tailings, 1323.0g of Gobi aggregate, 141.75g ​​of slag powder, 18.9g of quicklime, 9.45g of silica fume, 18.9g of desulfurized gypsum, 2.32g of NiCs-LDH@CuO powder prepared by S3, and 693mL of water. Place these into a cement mortar mixer and stir continuously for 5-8 minutes to ensure thorough and uniform mixing of the filling aggregate and cementitious material. Pour the slurry manually using a slurry ladle. To prevent sedimentation, stir continuously during pouring, following the direction of slurry rotation. Quickly remove the slurry and pour it into the standard mold. The filling slurry was evenly poured into three molds, extending 2 mm above the mold. After pouring, the molds were placed on a vibrating table for 30 seconds to compact. Excess slurry was scraped off from both sides of the mold with a trowel and the surface was gently smoothed. Demolding was performed 48 hours after pouring, separating the filling sample from the mold. An air pump was used to slowly remove the sample from the bottom of the mold to ensure its integrity. After demolding, the sample was placed in a standard constant temperature and humidity curing chamber at 20±2℃ and relative humidity greater than 90% for curing until the specified curing age was reached. Quicklime, silica fume, and desulfurized gypsum were mixed evenly in a certain proportion as a composite activator to activate the potential activity of the filling material and improve its mechanical properties and durability. Quicklime provides an alkaline environment, disrupting the silica-alumina glass structure and promoting dissolution; highly active SiO2 reacts with Ca(OH)2 to form CSH gel, improving the density and mechanical strength of the filling; desulfurized gypsum provides SO42-. 2- The silica fume reacts with the aluminum phase to form ettringite (AFt), compensating for shrinkage and enhancing early strength. NiCs-LDH in NiCs-LDH@CuO provides alkaline sites, promoting the destruction of the silica-alumina glass structure by quicklime, and also promoting the reaction of highly reactive SiO2 in silica fume with Ca(OH)2 to form CSH gel. Furthermore, silica fume can exert a "physical filling effect," improving the structural density of high-sulfur tailings backfill from a microscopic perspective; and highly reactive SiO2 generates silicate substances in an alkaline environment, with silicate compounds exhibiting superior performance compared to sulfate compounds.

[0044] Figure 1 This is a scanning electron microscope image of NiCs-LDH@CuO prepared in Example 1 of the present invention. Figure 2 The image shows the microstructure of the high-sulfur tailings backfill material prepared in Example 1 of this invention. Figure 2 It can be seen that the hydration process of slag powder first involves the hydration reaction of SiO2 and Al2O3 products inside the slag under alkaline conditions; secondly, with the continuous supply of water, it penetrates into the interior through the gaps between the hydration products on the slag surface until the slag is completely hydrated. Simultaneously, the formation of ettringite consumes the calcium aluminate generated during slag hydration, thereby promoting the hydration process of the slag and increasing the density of the internal structure of the filling body.

[0045] Example 2:

[0046] S1: Copper mesh processing: Take an area of ​​1.5cm² 2The copper mesh was placed in 10 ml of 1M hydrochloric acid and sonicated for 20 minutes. Then, the copper mesh was removed and placed in 10 ml of ethanol, and sonicated for another 10 minutes. Afterward, the copper mesh was removed and rinsed three times with deionized water. After cleaning, the copper mesh was sealed with deionized water. Soaking the copper mesh in hydrochloric acid was to remove irregular CuO and Cu2(OH)2CO3 impurities from its surface, while immersion in ethanol was to treat the acid adhering to the surface of the copper mesh.

[0047] S2: Preparation of CuO: Weigh 1.2g of KOH and 0.2g of K2S2O8, add 10ml of deionized water, and after the reagents are completely dissolved, put the treated copper mesh into the solution and keep the copper mesh completely immersed for 30 minutes. After taking out the copper mesh, put it into an oven and heat it at 120℃ for 30 minutes.

[0048] S3: Preparation of NiCs-LDH@CuO: Weigh 0.02g of NiCl2, 0.10g of CsCl, and 0.2g of hexamethylenetetramine, add 30ml of deionized water, place the copper sheet from step S2 into the solution, and then transfer it to a muffle furnace. Heat at 120℃ for 5 hours. After the muffle furnace cools, remove the sheet and dry it. This sheet is NiRb-LDH@CuO. Finally, use a rotary kneader to pulverize the sheet to obtain NiCs-LDH@CuO powder. NiCs-LDH@CuO, as a composite catalyst, can act as a highly efficient active activator in the quicklime-silica fume-desulfurized gypsum composite activation system, significantly improving the early hydration efficiency of cementitious materials. Its layered structure (LDH) regulates Ca through ion exchange. 2+ SO4 2- The release kinetics, and the semiconductor properties of CuO nanoparticles promote electron transfer, accelerating the hydrolysis of quicklime (CaO) and the dissolution of silica fume. This composite material can synergistically optimize the formation of ettringite (AFt) with desulfurized gypsum, enhance the density of the interfacial transition zone, and reduce the volume instability problems caused by traditional strong base activators.

[0049] S4: Referring to the "GB / T 51003-2014" Technical Specification for the Application of Mineral Admixtures, weigh out 534.6g of high-sulfur tailings, 891.0g of Gobi aggregate, 222.7g of slag powder, 29.70g of quicklime, 14.85g of silica fume, 29.70g of desulfurized gypsum, 2.32g of NiCs-LDH@CuO powder prepared by S3, and 621mL of water. Place these into a cement mortar mixer and stir continuously for 5 minutes to ensure thorough and uniform mixing of the filling aggregate and cementitious material. Pour the slurry manually using a slurry ladle. To prevent sedimentation, stir continuously during pouring, following the direction of slurry rotation. Quickly remove the slurry and pour it into the standard mold. The filling slurry was evenly poured into three molds, extending 2 mm above the mold. After pouring, the molds were placed on a vibrating table for 30 seconds to compact. Excess slurry was scraped off from both sides of the mold with a trowel and the surface was gently smoothed. Demolding was performed 48 hours after pouring, separating the filling sample from the mold. An air pump was used to slowly remove the sample from the bottom of the mold to ensure its integrity. After demolding, the sample was placed in a standard constant temperature and humidity curing chamber at 20±2℃ and relative humidity greater than 90% for curing until the specified curing age was reached. Quicklime, silica fume, and desulfurized gypsum were mixed evenly in a certain proportion as a composite activator to activate the potential activity of the filling material and improve its mechanical properties and durability. Quicklime provides an alkaline environment, disrupting the silica-alumina glass structure and promoting dissolution; highly active SiO2 reacts with Ca(OH)2 to form CSH gel, improving the density and mechanical strength of the filling; desulfurized gypsum provides SO42-. 2- The silica fume reacts with the aluminum phase to form ettringite (AFt), compensating for shrinkage and enhancing early strength. NiCs-LDH in NiCs-LDH@CuO provides alkaline sites, promoting the destruction of the silica-alumina glass structure by quicklime, and also promoting the reaction of highly reactive SiO2 in silica fume with Ca(OH)2 to form CSH gel. Furthermore, silica fume can exert a "physical filling effect," improving the structural density of high-sulfur tailings backfill from a microscopic perspective; and highly reactive SiO2 generates silicate substances in an alkaline environment, with silicate compounds exhibiting superior performance compared to sulfate compounds.

[0050] Comparative Example 1: Except for step S4, in which 29.70g of quicklime was not added, all other steps were the same as in Example 2.

[0051] Comparative Example 2: Except for step S4, in which 14.85g of silica fume is not added, all other steps are the same as in Example 2.

[0052] Comparative Example 3: Except for step S4, in which 29.70g of desulfurized gypsum was not added, all other steps were the same as in Example 2.

[0053] Comparative Example 4: Except for step S4, in which 2.32g of the NiCs-LDH@CuO powder prepared in S3 was not added, all other steps were the same as in Example 2.

[0054] Comparative Example 5: Except for step S4, in which 29.70g of quicklime, 14.85g of silica fume and 29.70g of desulfurized gypsum were not added, all other steps were the same as in Example 2.

[0055] Comparative Example 6: Except for step S4, in which 29.70g of quicklime, 14.85g of silica fume, 29.70g of desulfurized gypsum and 2.32g of NiCs-LDH@CuO powder prepared in S3 were not added, all other steps were the same as in Example 2.

[0056] Comparative Example 7: Except for step S4, in which the amount of high-sulfur tailings was changed to 801.9g, all other steps were the same as in Example 2.

[0057] This invention performs uniaxial compressive strength testing on specimens according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-1999). The standard mold used in this invention has the following dimensions: Uniaxial compressive strength tests (14d and 60d) were conducted using an INSTRON5969 electronic universal testing machine (load range 100kN), with a constant displacement loading rate of 0.5mm / min set, and the computer system collected load and displacement data in real time.

[0058] Table 5 shows the uniaxial compressive strength test results of the fillers prepared in Example 2 and Comparative Examples 1-7 of this invention. To avoid randomness in the experimental data, the test was conducted 5 times. Based on the comparison of the compressive strength values ​​at 14d and 60d, it can be seen that this invention uses quicklime, silica fume, and desulfurized gypsum in a certain proportion as an activator to activate the activity of potential cementitious materials. NiCs-LDH@CuO has a promoting effect on the composite activator. NiCs-LDH in NiCs-LDH@CuO provides alkaline sites, promoting the destruction of the silica-alumina glass structure by quicklime, and also promoting the reaction of highly active SiO2 in silica fume with Ca(OH)2 to generate CSH gel. Simultaneously, it can synergistically optimize the formation of ettringite (AFt) with desulfurized gypsum, enhance the density of the interfacial transition zone, and improve early strength. The uniaxial compressive strength test results of the fillers prepared in Example 2 and Comparative Examples 1-6 further demonstrate that the NiCs-LDH@CuO prepared in this invention improves the compressive strength and mechanical properties of the high-sulfur tailings-based filler excited by quicklime, silica fume, and desulfurized gypsum. Comparative Example 7 increased the content of high-sulfur tailings, making the content of high-sulfur tailings in this comparative example 1.5 times that of other comparative examples and examples. By analyzing the compressive strength of Comparative Example 7 and Comparative Example 4, it can be seen that the amount of tailings added in Comparative Example 7 (801.9g) is 1.5 times that of the control group (534.6g), while maintaining similar strength, proving that NiCs-LDH@CuO significantly improves the utilization rate of tailings, thereby greatly reducing the filling cost.

[0059] Table 5 Compressive strength of high-sulfur tailings-based backfill materials

[0060]

[0061]

[0062] Example 3:

[0063] S1: Copper mesh processing: Take an area of ​​1.5cm²2 The copper mesh was placed in 10 ml of 1M hydrochloric acid and sonicated for 20 minutes. Then, the copper mesh was removed and placed in 10 ml of ethanol, and sonicated for another 10 minutes. Afterward, the copper mesh was removed and rinsed three times with deionized water. After cleaning, the copper mesh was sealed with deionized water. Soaking the copper mesh in hydrochloric acid was to remove irregular CuO and Cu2(OH)2CO3 impurities from its surface, while immersion in ethanol was to treat the acid adhering to the surface of the copper mesh.

[0064] S2: Preparation of CuO: Weigh 1.2g of KOH and 0.2g of K2S2O8, add 10ml of deionized water, and after the reagents are completely dissolved, put the treated copper mesh into the solution and keep the copper mesh completely immersed for 30 minutes. After taking out the copper mesh, put it into an oven and heat it at 120℃ for 30 minutes.

[0065] S3: Preparation of NiCs-LDH@CuO: Weigh 0.05g of NiCl2, 0.25g of CsCl, and 0.5g of hexamethylenetetramine, add 50ml of deionized water, place the copper sheet from step S2 into the solution, and then transfer it to a muffle furnace. Heat at 120℃ for 5 hours. After the muffle furnace cools, remove the sheet and dry it. This sheet is NiRb-LDH@CuO. Finally, use a rotary kneader to pulverize the sheet to obtain NiCs-LDH@CuO powder. NiCs-LDH@CuO, as a composite catalyst, can act as a highly efficient active activator in the quicklime-silica fume-desulfurized gypsum composite activation system, significantly improving the early hydration efficiency of cementitious materials. Its layered structure (LDH) regulates Ca through ion exchange. 2+ SO4 2- The release kinetics, and the semiconductor properties of CuO nanoparticles promote electron transfer, accelerating the hydrolysis of quicklime (CaO) and the dissolution of silica fume. This composite material can synergistically optimize the formation of ettringite (AFt) with desulfurized gypsum, enhance the density of the interfacial transition zone, and reduce the volume instability problems caused by traditional strong base activators.

[0066] S4: Referring to the "GB / T 51003-2014" Technical Specification for the Application of Mineral Admixtures, weigh out 945.0g of high-sulfur tailings, 1323.0g of Gobi aggregate, 141.75g ​​of slag powder, 29.70g of quicklime, 14.85g of silica fume, 29.70g of desulfurized gypsum, 4.74g of NiCs-LDH@CuO powder prepared by S3, and 693mL of water. Place these into a cement mortar mixer and stir continuously for 5 minutes to ensure thorough and uniform mixing of the filling aggregate and cementitious material. Pour the slurry manually using a slurry ladle. To prevent sedimentation, stir continuously during pouring, following the direction of slurry rotation. Quickly remove the slurry and pour it into the standard mold. The filling slurry was evenly poured into three molds, extending 2 mm above the mold. After pouring, the molds were placed on a vibrating table for 30 seconds to compact. Excess slurry was scraped off from both sides of the mold with a trowel and the surface was gently smoothed. Demolding was performed 48 hours after pouring, separating the filling sample from the mold. An air pump was used to slowly remove the sample from the bottom of the mold to ensure its integrity. After demolding, the sample was placed in a standard constant temperature and humidity curing chamber at 20±2℃ and relative humidity greater than 90% for curing until the specified curing age was reached. Quicklime, silica fume, and desulfurized gypsum were mixed evenly in a certain proportion as a composite activator to activate the potential activity of the filling material and improve its mechanical properties and durability. Quicklime provides an alkaline environment, disrupting the silica-alumina glass structure and promoting dissolution; highly active SiO2 reacts with Ca(OH)2 to form CSH gel, improving the density and mechanical strength of the filling; desulfurized gypsum provides SO42-. 2- The silica fume reacts with the aluminum phase to form ettringite (AFt), compensating for shrinkage and enhancing early strength. NiCs-LDH in NiCs-LDH@CuO provides alkaline sites, promoting the destruction of the silica-alumina glass structure by quicklime, and also promoting the reaction of highly reactive SiO2 in silica fume with Ca(OH)2 to form CSH gel. Furthermore, silica fume can exert a "physical filling effect," improving the structural density of high-sulfur tailings backfill from a microscopic perspective; and highly reactive SiO2 generates silicate substances in an alkaline environment, with silicate compounds exhibiting superior performance compared to sulfate compounds.

[0067] The silica fume used in this invention has the following raw material analysis as shown in Table 6 and... Figure 3 As shown.

[0068] Table 6 Chemical composition of silica fume

[0069] content / % 0.83 95.9 0.10 1.31 0.63 0.13 0.33 0.77

[0070] Figure 3 The image shows the XRD pattern of silica fume. Table 6 shows the chemical composition of the silica fume. Table 6 shows that the effective chemical composition of the silica fume used has a SiO2 content of 95.9%; according to... Figure 3 XRD results showed that characteristic peaks of SiO2 were observed near diffraction angles of 21° and 26°. These SiO2 peaks had the highest peak values ​​and the widest diffraction peak widths, indicating the presence of a considerable amount of amorphous active SiO2 in the silica fume. This amorphous SiO2 reacts with Ca(OH)2, a cement hydration product, to generate more CSH gel (secondary hydration), strengthening the cementitious structure and compensating for the strength loss caused by sulfide oxidation in high-sulfur tailings. Compared to general industrial waste ash (fly ash, limestone powder, stone powder, etc.), silica fume exhibits higher activity. The active silanol groups (Si-OH) on the surface of silica fume can adsorb sulfate ions (SO42-). 2- This reduces the damage to the cementitious structure caused by sulfate erosion.

[0071] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A cementitious material suitable for high-sulfur tailings backfill, characterized in that: It contains slag powder, quicklime, silica fume, desulfurized gypsum, and NiCs-LDH@CuO powder; each component contains, by weight, 141.75-222.75 parts slag powder, 18.9-29.7 parts quicklime, 9.45-14.85 parts silica fume, 18.9-29.7 parts desulfurized gypsum, and 2.32-4.74 g parts NiCs-LDH@CuO powder; The preparation method of the NiCs-LDH@CuO powder includes the following steps: S1. Place the copper mesh in hydrochloric acid solution and sonicate it in an ultrasonic instrument. Then remove the copper mesh, place it in ethanol, and continue to sonicate it in an ultrasonic instrument. Then remove the copper mesh and rinse it with deionized water 2-3 times. After cleaning, seal the copper mesh with deionized water. S2. Weigh KOH and K2S2O8, add deionized water, and after the chemicals are completely dissolved, put the treated copper mesh into the solution and keep the copper mesh completely immersed. Then take out the copper mesh and put it into an oven and heat it at 120-200℃ for 30-50 minutes. S3. Weigh out NiCl2, CsCl and hexamethylenetetramine, add deionized water, put the copper sheet from step S2 into it, and then transfer it to a muffle furnace. Heat it at 100-150℃ for 3-6 hours. After the muffle furnace cools down, take out the sheet and dry it. This sheet is NiCs-LDH@CuO. Finally, use a rotary mixer to pulverize the sheet to obtain NiCs-LDH@CuO powder.

2. A method for preparing a high-sulfur tailings backfill containing the cementitious material of claim 1, characterized in that: The specific operating steps are as follows: S1: Copper mesh processing: Take an area of ​​0.8-1.5cm². 2 The copper mesh is placed in 5-10 ml of 1M hydrochloric acid and sonicated for 15-20 minutes. Then, the copper mesh is removed and placed in 5-10 ml of ethanol, and sonicated for another 5-10 minutes. The copper mesh is then removed and rinsed 2-3 times with deionized water. After rinsing, the copper mesh is sealed with deionized water. S2: Preparation of CuO: Weigh 1.2-2.3 g of KOH and 0.2-0.5 g of K2S2O8, add 10-30 ml of deionized water, and after the chemicals are completely dissolved, place the treated copper mesh in the solution, keeping it completely immersed for 30-50 minutes. After removing the copper mesh, place it in an oven to dry. S3: Preparation of NiCs-LDH@CuO: Weigh 0.02-0.05g of NiCl2, 0.10-0.25g of CsCl and 0.2-0.5g of hexamethylenetetramine, add 30-50ml of deionized water, put the copper sheet from step S2 into it, and then transfer it to a muffle furnace. Heat at 100-150℃ for 3-6h. After the muffle furnace cools down, take out the sheet and dry it. This sheet is NiCs-LDH@CuO. Finally, use a rotary mixer to pulverize the sheet to obtain NiCs-LDH@CuO powder; S4: Refer to "GB / T According to the "Technical Specification for Application of Mineral Admixtures" (51003-2014), the following amounts are to be weighed: 534.6-945.0g of high-sulfur tailings, 891.0-1323.0g of Gobi aggregate, 141.75-222.75g of slag powder, 18.9-29.7g of quicklime, 9.45-14.85g of silica fume, 18.9-29.7g of desulfurized gypsum, and 2.32-4.74g of NiCs-LDH prepared from S3. Mix CuO powder and 621-693 ml of water in a cement mortar mixer and stir continuously for 5-8 minutes to ensure thorough and uniform mixing of the filling aggregate and cementitious material. Pour the slurry manually using a slurry ladle. To prevent sedimentation, stir continuously while pouring, following the direction of slurry rotation. Quickly remove the slurry and pour it into a standard mold (φ50mm×100mm). Evenly pour the filling slurry into three molds, ensuring the slurry level exceeds the mold by 2 mm. After pouring, place the mold on a vibrating table for 30 seconds to compact. Use a trowel to scrape off excess cement from both sides of the mold and gently smooth the surface. Demold 48 hours after pouring by separating the filling sample from the mold. Use an air pump to slowly remove the sample from the bottom of the mold to ensure its integrity. After demolding, place the sample in a standard constant temperature and humidity curing chamber at 20±2℃ and relative humidity greater than 90% until the specified curing age is reached.

3. The method for preparing a high-sulfur tailings backfill body according to claim 2, characterized in that: In step S1, the area is taken as 0.8 cm². 2 The copper mesh was placed in 5 ml of 1M hydrochloric acid and sonicated in an ultrasonic instrument for 15 minutes. Then the copper mesh was removed and placed in 5 ml of ethanol and sonicated in an ultrasonic instrument for another 5 minutes. The copper mesh was then removed and rinsed twice with deionized water. After cleaning, the copper mesh was sealed with deionized water.

4. The method for preparing a high-sulfur tailings backfill body according to claim 2, characterized in that: In step S1, the area is 1.5 cm². 2 The copper mesh was placed in 10 ml of 1M hydrochloric acid and sonicated in an ultrasonic instrument for 20 minutes. Then the copper mesh was removed and placed in 10 ml of ethanol and sonicated in an ultrasonic instrument for another 10 minutes. The copper mesh was then removed and rinsed three times with deionized water. After cleaning, the copper mesh was sealed with deionized water.

5. The method for preparing a high-sulfur tailings backfill body according to claim 2, characterized in that: In step S2, weigh 1.2g of KOH and 0.2g of K2S2O8, add 10ml of deionized water, and after the chemicals are completely dissolved, put the treated copper mesh into the solution and keep the copper mesh completely immersed for 30 minutes. After taking out the copper mesh, put it into an oven and heat it at 120℃ for 30 minutes.

6. The method for preparing a high-sulfur tailings backfill body according to claim 2, characterized in that: In step S3, 0.02g of NiCl2, 0.10g of CsCl and 0.2g of hexamethylenetetramine are weighed and added to 30ml of deionized water. The copper sheet from step S2 is then placed in the solution and transferred to a muffle furnace. The solution is heated at 120°C for 5 hours. After the muffle furnace cools down, the resulting sheet is removed and dried. This sheet is NiCs-LDH@CuO. Finally, the sheet is pulverized using a rotary kneader to obtain NiCs-LDH@CuO powder.

7. The method for preparing a high-sulfur tailings backfill body according to claim 2, characterized in that: In step S3, 0.05g of NiCl2, 0.25g of CsCl and 0.5g of hexamethylenetetramine are weighed and added to 50ml of deionized water. The copper sheet from step S2 is then placed in the solution and transferred to a muffle furnace. The solution is heated at 120°C for 5 hours. After the muffle furnace cools down, the resulting sheet is removed and dried. This sheet is NiCs-LDH@CuO. Finally, the sheet is pulverized using a rotary kneader to obtain NiCs-LDH@CuO powder.

8. The method for preparing a high-sulfur tailings backfill body according to claim 2, characterized in that: Following the "GB / T51003-2014" technical specification for the application of mineral admixtures, 534.6g of high-sulfur tailings, 891.0g of Gobi aggregate, 222.7g of slag powder, 29.70g of quicklime, 14.85g of silica fume, 29.70g of desulfurized gypsum, 2.32g of NiCs-LDH@CuO powder prepared from S3, and 621ml of water were weighed and placed in a cement mortar mixer and continuously stirred for 5 minutes to ensure thorough and uniform mixing of the filling aggregate and cementitious material. The slurry was manually poured using a slurry ladle. To prevent sedimentation, the slurry was stirred continuously during pouring, following the direction of rotation. The slurry was then quickly removed and poured into a standard mold (φ50mm×100mm). The filling slurry was evenly poured into three molds, with the height exceeding the mold by 2. mm; After pouring, place the sample on a vibrating table for 30 seconds of compaction. Use a trowel to scrape off excess adhesive from both sides of the mold and smooth it gently. Demolding is performed 48 hours after pouring, that is, separating the filling sample from the mold. Demolding is done by using an air pump to slowly remove the sample from the bottom of the mold to ensure its integrity. After demolding, place the sample in a standard constant temperature and humidity curing chamber with a temperature of 20±2℃ and a relative humidity greater than 90% for curing until the specified curing age is reached.

9. The high-sulfur tailings backfill body prepared by any one of the preparation methods according to claims 2-8.

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