Preparation process of a high-strength cement-based mine backfill material containing modified slag soil

Abstract

This invention relates to the field of building materials, specifically disclosing a preparation process for a high-strength cement-based mine backfill material containing modified slag, comprising the following steps: (1) calcining halloysite powder, then mixing the resulting pretreated powder with slag powder and grinding it. After completion, adding lithium fluorosilicate aqueous solution to the resulting mixed powder, mixing and drying to obtain modified slag powder. (2) Preparing modified plastic fibers with iron oxide nanoparticles and nano silica loaded on the surface. (3) Using cement, fine aggregate, granulated blast furnace slag powder, water-reducing agent, modified plastic fibers, and modified slag powder as raw materials, mixing them evenly, adding water and stirring evenly to obtain the cement-based mine backfill material. This invention effectively improves the mechanical strength and impermeability of the prepared cement-based mine backfill material through the reprocessing of slag and the synergistic effect of modified fibers, which helps to promote the resource utilization of slag.

Description

Technical Field

[0001] This invention relates to the field of building materials, specifically to a preparation process for a high-strength cement-based mine backfill material containing modified slag. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] In the process of mineral resource development, the treatment of goaf areas and the control of surface subsidence have always been core challenges facing mining engineering. Traditional mining methods rely on reserving coal pillars to prevent goaf collapse, but this leads to a significant waste of coal resources and cannot guarantee long-term protection against surface subsidence. With the deepening of the green development concept and the increasing national requirements for mine ecological restoration, backfilling mining technology has emerged. Cement-based mine backfill materials are special engineering materials with cement as the main binding component, used to fill underground goaf areas. They are an indispensable material foundation in modern mining engineering. They are typically composed of three main parts: aggregates, cementitious materials, and water. Small amounts of admixtures to improve the performance of the backfill material can also be added. Cement-based mine backfill materials have advantages such as stable strength development and reliable performance, and have been widely used in mine backfilling.

[0004] Construction waste refers to the excavated soil generated during the construction of various buildings, structures, pipelines, roads, and bridges. It is currently the most common and largest type of construction waste, but its resource utilization rate is insufficient. Furthermore, construction waste is often transported to landfills due to difficulties in backfilling and high dewatering costs, occupying a large amount of land annually and easily causing dust pollution and safety hazards. Using construction waste in cement-based mine backfill materials not only facilitates large-scale resource utilization but also meets the needs of mine backfilling. However, due to the weak interfacial bonding between construction waste and the cement-based mine backfill material matrix, numerous weak interfacial areas are formed. Incorporating construction waste into cement-based mine backfill materials leads to deterioration of the structural strength and insufficient impermeability of the hardened backfill, limiting the application of construction waste in this field. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a preparation process for a high-strength cement-based mine backfill material containing modified slag. Through the reprocessing of the slag and the synergistic effect of modified fibers, the mechanical strength and impermeability of the prepared cement-based mine backfill material are effectively improved, which helps to promote the resource utilization and large-scale use of slag. Specifically, the technical solution of this invention is as follows.

[0006] A preparation process for a high-strength cement-based mine backfill material containing modified slag soil includes the following steps: (1) The halloysite powder was calcined, and then the pretreated powder was mixed with the slag powder and ground. After the mixture was ground, lithium fluorosilicate aqueous solution was added to the mixed powder, mixed well and dried to obtain modified slag powder.

[0007] (2) The plastic fiber is added to anhydrous ethanol containing silane coupling agent, mixed and allowed to stand. Then, iron oxide nanoparticles and nano-silica are added and stirred. After completion, the fiber is separated, dried, and then microwave-heated. After cooling, the modified plastic fiber is obtained.

[0008] (3) Using cement, fine aggregate, granulated blast furnace slag powder, water-reducing agent, modified slag powder, and modified plastic fiber as raw materials, mix them evenly and then add water and stir evenly to obtain the cement-based mine filling material.

[0009] Furthermore, in step (1), the calcination treatment is carried out at a temperature of 520~560℃ for 1.5~2.5 hours.

[0010] Further, in step (1), the mass ratio of the pretreated powder to the slag powder is 24~32:100. Optionally, the fineness of the mixed powder is 120~200 mesh.

[0011] Further, in step (1), the ratio of the mixed powder to the lithium fluorosilicate aqueous solution is 1g:8~12mL. Optionally, the mass fraction of the lithium fluorosilicate aqueous solution is 20~30%.

[0012] Further, in step (1), the drying temperature is 100~140℃, and the modified slag powder is obtained by drying at this temperature until the mass of the mixture no longer changes.

[0013] Further, in step (2), the ratio of the plastic fiber to anhydrous ethanol is 1g: 55~70mL. Optionally, the standing time is 10~15min.

[0014] Further, in step (2), the plastic fiber includes at least one of polyethylene fiber, polypropylene fiber, polyamide fiber, etc. Optionally, the plastic fiber has a length of 3~5mm and a diameter of 0.15~0.22mm.

[0015] Further, in step (2), the mass fraction of the silane coupling agent in the anhydrous ethanol is 0.35~0.6%. Optionally, the silane coupling agent includes at least one of KH550, KH560, KH570, etc.

[0016] Furthermore, in step (2), the content of iron tetroxide nanopowder in the anhydrous ethanol is 15~20g / L, and the content of nano silica is 8~11g / L.

[0017] Further, in step (2), the stirring time is 5-10 minutes. Optionally, the drying temperature is 70-75°C and the time is 1-2 hours.

[0018] Furthermore, in step (2), the microwave heating treatment time is 10~15min and the microwave power is 800~1000W.

[0019] Further, in step (3), the proportions of each component in the raw materials are as follows: 205-220 parts by weight of cement, 285-310 parts by weight of fine aggregate, 21-33 parts by weight of granulated blast furnace slag powder, 3-3.8 parts by weight of water-reducing agent, 42-50 parts by weight of modified slag powder, 16-24 parts by weight of modified plastic fiber, and 90-112 parts by weight of clean water.

[0020] Further, in step (3), the fine aggregate includes at least one of river sand, quartz sand, etc. Optionally, the particle size of the fine aggregate is 1~3mm.

[0021] Furthermore, in step (3), the fineness of the granulated blast furnace slag powder is 400~500 mesh.

[0022] Compared with the prior art, the present invention has at least the following beneficial technical effects: This invention first involves co-grinding pretreated powder (formed through calcination) with slag powder to form intercalated microparticles. After calcination, the pretreated powder retains the fibrous structure of halloysite while its composition is transformed into active silica and alumina. This is then further processed with lithium fluorosilicate to form the modified slag powder. When incorporated into cement-based mine backfill materials, the fibrous active silica and alumina react with calcium hydroxide, a hydration product of cement, to form hydrated calcium silicate (CSH) and hydrated calcium aluminate (CAH) cementitious components, while maintaining the fibrous structure. This invention, by modifying halloysite to replicate its fibrous structure and obtain fibrous cementitious components, effectively improves the bonding force between slag and the backfill material matrix, reduces weak interface areas, and enhances the mechanical properties and impermeability of cement-based mine backfill materials containing slag. Simultaneously, the lithium ions provided by the lithium fluorosilicate can promote the formation of CSH and CAH. Some lithium ions enter the cementitious component to form Li-CSH and Li-CAH, which can effectively increase the density of the fibrous cementitious component, solidify the interface transition zone, and improve strength and impermeability. Furthermore, the calcium fluorosilicate formed by the reaction of the fluorosilicate ions provided by the lithium fluorosilicate with calcium hydroxide further decomposes in the alkaline environment of the filling material to form calcium fluoride and silica. The calcium fluoride filling the cementitious component can improve its density, and the silica reacting with calcium hydroxide to convert into CSH can further reinforce the fibrous cementitious component, reduce structural defects in the fiber body, and thus improve its strength. In addition, the lithium ions can effectively increase the alkalinity of the filling material system, promote the deagglomeration of mineral phases in the granulated blast furnace slag powder, enhance hydration activity, and form more cementitious products, thereby improving the mechanical strength of the filling material of this invention. In addition, the present invention loads iron oxide and nano-silica onto the surface of plastic fibers before subjecting them to microwave heating treatment. This utilizes the microwave absorption and heat generation effect of the iron oxide to partially melt the surface of the plastic fibers. After cooling, the iron oxide and nano-silica adhering to the fiber surface, as well as the pits caused by the partial melting, can effectively increase the surface roughness of the fibers. At the same time, the cementitious component CSH formed by the reaction of the nano-silica with calcium hydroxide, a cement hydration product, can further enhance the bonding force between the fibers and the filling material matrix, thereby improving the strength of the cement-based mine filling material of the present invention. Attached Figure Description

[0023] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings, wherein: Figure 1 The modified slag powder is prepared in Example 1 below.

[0024] Figure 2 The image shows the compressive strength test results of the cement-based mine filling material prepared in Example 1 below.

[0025] Figure 3 The modified slag powder is prepared in Example 2 below.

[0026] Figure 4 The image shows the compressive strength test results of the cement-based mine filling material prepared in Example 2 below.

[0027] Figure 5 The modified slag powder is prepared in Example 3 below.

[0028] Figure 6 The image shows the compressive strength test results of the cement-based mine filling material prepared in Example 3 below.

[0029] Figure 7 The modified slag powder is prepared in Example 4 below.

[0030] Figure 8 The image shows the compressive strength test results of the cement-based mine filling material prepared in Example 4 below.

[0031] Figure 9 The modified slag powder prepared in Example 5 below.

[0032] Figure 10 The image shows the compressive strength test results of the cement-based mine backfill material prepared in Example 5 below.

[0033] Figure 11 The compressive strength test diagram is shown for the cement-based mine filling material prepared in Example 6 below.

[0034] Figure 12 The compressive strength test diagram is shown for the cement-based mine filling material prepared in Example 7 below.

[0035] Figure 13 The compressive strength test diagram is shown for the cement-based mine filling material prepared in Example 8 below. Detailed Implementation

[0036] The present invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention.

[0038] Example 1 A preparation process for a high-strength cement-based mine backfill material containing modified slag soil includes the following steps: (1) Halloysite powder was calcined at 540℃ for 2 hours and then cooled to room temperature to obtain pretreated powder. The pretreated powder was then mixed with slag powder at a mass ratio of 30:100 and ground for 1 hour. The mixture was then passed through a 150-mesh sieve to obtain a mixed powder. This mixed powder was then mixed with a 25% lithium fluorosilicate aqueous solution at a mass ratio of 1g:10mL and stirred until homogeneous. The mixture was then heated to 120℃ and dried until the mass of the mixture no longer changed. After grinding, it was passed through a 150-mesh sieve to obtain modified slag powder (e.g., Figure 1 (As shown), for later use.

[0039] (2) Polyethylene fiber filaments with a length of 5 mm and a diameter of 0.2 mm were added to anhydrous ethanol containing 0.4 wt.% silane coupling agent (KH550) and stirred evenly in a ratio of 1 g: 60 mL. After standing for 10 min, the iron oxide nanoparticles and nano silica were added according to the ratio of 18 g / L and 10 g / L of iron oxide nanoparticles and nano silica in the anhydrous ethanol, respectively. After stirring continuously for 10 min, the mixture was allowed to stand for 2 min, the fiber was filtered out, and then heated to 70 °C and dried for 2 hours. Finally, the obtained fiber was subjected to microwave heating treatment for 15 min at a microwave power of 850 W. After cooling to room temperature, the modified plastic fiber was obtained and set aside for later use.

[0040] (3) Take the following raw materials in the following proportions: 215 parts by weight of silicate cement (PO 42.5), 300 parts by weight of fine aggregate, 27 parts by weight of granulated blast furnace slag powder, 3.5 parts by weight of polycarboxylate superplasticizer, 48 parts by weight of modified slag powder in this embodiment, and 20 parts by weight of modified plastic fiber in this embodiment. The fine aggregate is river sand with a particle size distribution between 1 and 3 mm, and the fineness of the granulated blast furnace slag powder is 500 mesh. Add the above raw materials to a mixer and mix for 3 minutes, then add 102 parts by weight of clean water and continue mixing for 2 minutes to obtain the cement-based mine filling material.

[0041] Performance testing: The compressive strength (e.g., ...) of the cement-based mine filling material prepared in this embodiment was tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019) and the "Standard for Test Methods of Long-Term Performance and Durability of Concrete" (GBT 50082-2024). Figure 2 The results of the anti-permeability tests (as shown in the table below) are as follows.

[0042]

[0043] Example 2 A preparation process for a high-strength cement-based mine backfill material containing modified slag soil includes the following steps: (1) Halloysite powder was calcined at 520℃ for 2.5 hours and then cooled to room temperature to obtain pretreated powder. This pretreated powder was then mixed with slag powder at a mass ratio of 32:100 and ground for 1.5 hours. The mixture was then passed through a 200-mesh sieve to obtain a mixed powder. This mixed powder was then mixed with a 30% lithium fluorosilicate aqueous solution at a mass ratio of 1g:8mL and stirred until homogeneous. The mixture was then heated to 100℃ and dried until the mass of the mixture no longer changed. After grinding, it was passed through a 200-mesh sieve to obtain modified slag powder (e.g., Figure 3 (As shown), for later use.

[0044] (2) Polyethylene fiber filaments with a length of 3 mm and a diameter of 0.15 mm were added to anhydrous ethanol containing 0.6 wt.% silane coupling agent (KH570) and stirred evenly in a ratio of 1 g: 55 mL. After standing for 10 min, the iron oxide nanoparticles and nano silica were added to the anhydrous ethanol in a ratio of 15 g / L and 8 g / L, respectively. After stirring continuously for 5 min, the fibers were filtered out and then heated to 70 °C and dried for 2 hours. Finally, the obtained fibers were microwave-treated for 10 min at a microwave power of 1000 W and cooled to room temperature to obtain modified plastic fibers for later use.

[0045] (3) Take the following raw materials in the following proportions: 220 parts by weight of silicate cement (PO 42.5), 310 parts by weight of fine aggregate, 33 parts by weight of granulated blast furnace slag powder, 3.8 parts by weight of polycarboxylate superplasticizer, 50 parts by weight of modified slag powder in this embodiment, and 24 parts by weight of modified plastic fiber in this embodiment. The fine aggregate is river sand with a particle size distribution between 1 and 3 mm, and the granulated blast furnace slag powder has a fineness of 400 mesh. Add the above raw materials to a mixer and mix for 3 minutes, then add 112 parts by weight of clean water and continue mixing for 2 minutes to obtain the cement-based mine filling material.

[0046] Performance testing: The compressive strength (e.g., ...) of the cement-based mine backfill material prepared in this embodiment was tested using the same method as in Example 1 above. Figure 4 The results of the anti-permeability tests (as shown in the table below) are as follows.

[0047]

[0048] Example 3 A preparation process for a high-strength cement-based mine backfill material containing modified slag soil includes the following steps: (1) Halloysite powder was calcined at 560℃ for 1.5 hours and then cooled to room temperature to obtain pretreated powder. This pretreated powder was then mixed with slag powder at a mass ratio of 24:100 and ground for 1 hour. The mixture was then passed through a 120-mesh sieve to obtain a mixed powder. This mixed powder was then mixed with a 20% lithium fluorosilicate aqueous solution at a mass ratio of 1g:12mL and stirred until homogeneous. The mixture was then heated to 140℃ and dried until the mass of the mixture no longer changed. After grinding, it was passed through a 120-mesh sieve to obtain modified slag powder (e.g., Figure 5 (As shown), for later use.

[0049] (2) Polypropylene fibers with a length of 4 mm and a diameter of 0.22 mm were added to anhydrous ethanol containing 0.35 wt.% silane coupling agent (KH560) and stirred evenly in a ratio of 1 g: 70 mL. The mixture was then allowed to stand for 15 min. Then, the iron oxide nanoparticles and nano silica were added to the anhydrous ethanol at a ratio of 20 g / L and 11 g / L, respectively. The mixture was stirred continuously for 10 min and allowed to stand for 2 min. The fibers were then filtered out and dried at 75 °C for 1 hour. Finally, the obtained fibers were subjected to microwave heating treatment for 15 min at a microwave power of 800 W. After cooling to room temperature, the modified plastic fibers were obtained and ready for use.

[0050] (3) Take the following raw materials in the following proportions: 205 parts by weight of silicate cement (PO 42.5), 285 parts by weight of fine aggregate, 21 parts by weight of granulated blast furnace slag powder, 3 parts by weight of polycarboxylate superplasticizer, 42 parts by weight of modified slag powder in this embodiment, and 16 parts by weight of modified plastic fiber in this embodiment. The fine aggregate is quartz sand with a particle size distribution between 1 and 3 mm, and the fineness of the granulated blast furnace slag powder is 450 mesh. Add the above raw materials to a mixer and mix for 3 minutes, then add 90 parts by weight of clean water and continue mixing for 2 minutes to obtain the cement-based mine filling material.

[0051] Performance testing: The compressive strength (e.g., ...) of the cement-based mine backfill material prepared in this embodiment was tested using the same method as in Example 1 above. Figure 6 The results of the anti-permeability tests (as shown in the table below) are as follows.

[0052]

[0053] Example 4 A preparation process for a high-strength cement-based mine backfill material containing modified slag soil includes the following steps: (1) Halloysite powder and slag powder were mixed at a mass ratio of 30:100 and ground for 1 hour. The mixture was then passed through a 150-mesh sieve to obtain a mixed powder. This mixed powder was then mixed with a 25% lithium fluorosilicate aqueous solution at a mass ratio of 1g:10mL and stirred until homogeneous. The mixture was then heated to 120℃ and dried until the mass of the mixture no longer changed. After grinding, it was passed through a 150-mesh sieve to obtain modified slag powder (e.g., Figure 7 (As shown), for later use.

[0054] (2) Take the following raw materials in the following proportions: 215 parts by weight of silicate cement (PO 42.5), 300 parts by weight of fine aggregate, 27 parts by weight of granulated blast furnace slag powder, 3.5 parts by weight of polycarboxylate superplasticizer, 48 parts by weight of modified slag powder of this embodiment, and 20 parts by weight of modified plastic fiber of the above embodiment 1. Wherein, the fine aggregate is river sand with a particle size distribution between 1 and 3 mm, and the fineness of the granulated blast furnace slag powder is 500 mesh. Add the above raw materials to a mixer and mix for 3 minutes, then add 102 parts by weight of clean water and continue mixing for 2 minutes to obtain cement-based mine filling material.

[0055] Performance testing: The compressive strength (e.g., ...) of the cement-based mine backfill material prepared in this embodiment was tested using the same method as in Example 1 above. Figure 8 The results of the anti-permeability tests (as shown in the table below) are as follows.

[0056]

[0057] Example 5 A preparation process for a high-strength cement-based mine backfill material containing modified slag soil includes the following steps: (1) Halloysite powder was heated to 540℃ and calcined for 2 hours, then cooled to room temperature to obtain pretreated powder. This pretreated powder was then mixed with slag powder at a mass ratio of 30:100 and ground for 1 hour. The mixture was then passed through a 150-mesh sieve to obtain modified slag powder (e.g., Figure 9 (As shown), for later use.

[0058] (2) Take the following raw materials in the following proportions: 215 parts by weight of silicate cement (PO 42.5), 300 parts by weight of fine aggregate, 27 parts by weight of granulated blast furnace slag powder, 3.5 parts by weight of polycarboxylate superplasticizer, 48 parts by weight of modified slag powder of this embodiment, and 20 parts by weight of modified plastic fiber of the above embodiment 1. Wherein, the fine aggregate is river sand with a particle size distribution between 1 and 3 mm, and the fineness of the granulated blast furnace slag powder is 500 mesh. Add the above raw materials to a mixer and mix for 3 minutes, then add 102 parts by weight of clean water and continue mixing for 2 minutes to obtain cement-based mine filling material.

[0059] Performance testing: The compressive strength (e.g., ...) of the cement-based mine backfill material prepared in this embodiment was tested using the same method as in Example 1 above. Figure 10 The results of the anti-permeability tests (as shown in the table below) are as follows.

[0060]

[0061] Example 6 A preparation process for a high-strength cement-based mine backfill material containing modified slag soil includes the following steps: The following raw materials were prepared in the following proportions: 215 parts by weight of silicate cement (PO 42.5), 300 parts by weight of fine aggregate, 27 parts by weight of granulated blast furnace slag powder, 3.5 parts by weight of polycarboxylate superplasticizer, 48 parts by weight of 150-mesh slag powder, and 20 parts by weight of the modified plastic fiber from Example 1 above. The fine aggregate was river sand with a particle size distribution between 1 and 3 mm, and the granulated blast furnace slag powder had a fineness of 500 mesh. All the above raw materials were added to a mixer and mixed for 3 minutes. Then, 102 parts by weight of water were added and the mixture was stirred for another 2 minutes to obtain the cement-based mine backfill material.

[0062] Performance testing: The compressive strength (e.g., ...) of the cement-based mine backfill material prepared in this embodiment was tested using the same method as in Example 1 above. Figure 11 The results of the anti-permeability tests (as shown in the table below) are as follows.

[0063]

[0064] Example 7 A preparation process for a high-strength cement-based mine backfill material containing modified slag soil includes the following steps: The following raw materials were prepared in the following proportions: 220 parts by weight of silicate cement (PO 42.5), 310 parts by weight of fine aggregate, 33 parts by weight of granulated blast furnace slag powder, 3.8 parts by weight of polycarboxylate superplasticizer, 50 parts by weight of modified slag powder from Example 2 above, and 24 parts by weight of polyethylene fiber filaments. The fine aggregate was river sand with a particle size distribution between 1 and 3 mm, the granulated blast furnace slag powder had a fineness of 400 mesh, and the polyethylene fiber filaments had a length of 3 mm and a diameter of 0.15 mm. All the above raw materials were added to a mixer and mixed for 3 minutes. Then, 112 parts by weight of water were added and the mixture was stirred for another 2 minutes to obtain the cement-based mine backfill material.

[0065] Performance testing: The compressive strength (e.g., ...) of the cement-based mine backfill material prepared in this embodiment was tested using the same method as in Example 1 above. Figure 12 The results of the anti-permeability tests (as shown in the table below) are as follows.

[0066]

[0067] Example 8 A preparation process for a high-strength cement-based mine backfill material containing modified slag soil includes the following steps: (1) Add polypropylene fiber with a length of 4 mm and a diameter of 0.22 mm to anhydrous ethanol containing 0.35 wt.% silane coupling agent (KH560) and stir evenly. The ratio of the two is 1 g: 70 mL. Then let it stand for 15 min. Then add the iron oxide nanoparticles and nano silica in the anhydrous ethanol at a ratio of 20 g / L and 11 g / L, respectively. Stir continuously for 10 min and let it stand for 2 min. Filter out the fiber and then heat it to 75 °C and dry it for 1 hour to obtain modified plastic fiber for later use.

[0068] (2) Take the following raw materials in the following proportions: 205 parts by weight of silicate cement (PO 42.5), 285 parts by weight of fine aggregate, 21 parts by weight of granulated blast furnace slag powder, 3 parts by weight of polycarboxylate superplasticizer, 42 parts by weight of modified slag powder from Example 3 above, and 16 parts by weight of modified plastic fiber from this example. The fine aggregate is quartz sand with a particle size distribution between 1 and 3 mm, and the granulated blast furnace slag powder has a fineness of 450 mesh. Add the above raw materials to a mixer and mix for 3 minutes, then add 90 parts by weight of clean water and continue mixing for 2 minutes to obtain the cement-based mine backfill material.

[0069] Performance testing: The compressive strength (e.g., ...) of the cement-based mine backfill material prepared in this embodiment was tested using the same method as in Example 1 above. Figure 13 The results of the anti-permeability tests (as shown in the table below) are as follows.

[0070]

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. 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 spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A preparation process for a high-strength cement-based mine backfill material containing modified slag, characterized in that, Includes the following steps: (1) Calcining halloysite powder, then mixing the pretreated powder with slag powder and grinding it; after completion, adding lithium fluorosilicate aqueous solution to the mixed powder, mixing and drying to obtain modified slag powder. (2) The plastic fiber is added to anhydrous ethanol containing silane coupling agent, mixed and allowed to stand, and then iron oxide nanopowder and nano silica are added and stirred. After completion, the fiber is separated and dried, and then microwave heating is performed to utilize the microwave absorption and heat generation effect of iron oxide to locally melt the surface of the plastic fiber. After cooling, the modified plastic fiber is obtained. (3) Take the following components in the following proportions: 205-220 parts by weight of cement, 285-310 parts by weight of fine aggregate, 21-33 parts by weight of granulated blast furnace slag powder, 3-3.8 parts by weight of water-reducing agent, 42-50 parts by weight of the modified slag powder, and 16-24 parts by weight of the modified plastic fiber; mix the above components evenly and add 90-112 parts by weight of water and stir evenly to obtain the cement-based mine filling material.

2. The preparation process of the high-strength cement-based mine backfill material containing modified slag as described in claim 1, characterized in that, In step (1), the calcination treatment is carried out at a temperature of 520~560℃ for 1.5~2.5 hours.

3. The preparation process of the high-strength cement-based mine backfill material containing modified slag as described in claim 1, characterized in that, In step (1), the mass ratio of the pretreated powder to the slag powder is 24~32:100; or, in step (1), the fineness of the mixed powder is 120~200 mesh.

4. The preparation process of the high-strength cement-based mine backfill material containing modified slag as described in claim 1, characterized in that, In step (1), the ratio of the mixed powder to the lithium fluorosilicate aqueous solution is 1g: 8~12mL; Alternatively, in step (1), the mass fraction of the lithium fluorosilicate aqueous solution is 20-30%; Alternatively, in step (1), the drying temperature is 100~140℃, and the modified slag powder is obtained by drying at this temperature until the mass of the mixture no longer changes.

5. The preparation process of the high-strength cement-based mine backfill material containing modified slag as described in claim 1, characterized in that, In step (2), the ratio of plastic fiber to anhydrous ethanol is 1g: 55~70mL; or, in step (2), the standing time is 10~15min.

6. The preparation process of the high-strength cement-based mine backfill material containing modified slag as described in claim 1, characterized in that, In step (2), the mass fraction of the silane coupling agent in the anhydrous ethanol is 0.35~0.6%.

7. The preparation process of the high-strength cement-based mine backfill material containing modified slag as described in claim 1, characterized in that, In step (2), the plastic fiber includes at least one of polyethylene fiber, polypropylene fiber, and polyamide fiber; Alternatively, in step (2), the silane coupling agent includes at least one of KH550, KH560, and KH570; Alternatively, in step (2), the length of the plastic fiber is 3~5mm and the diameter is 0.15~0.22mm.

8. The preparation process of the high-strength cement-based mine backfill material containing modified slag as described in claim 1, characterized in that, In step (2), the content of iron oxide nanoparticles in the anhydrous ethanol is 15~20g / L; Alternatively, in step (2), the content of the nano-silica is 8~11 g / L; Alternatively, in step (2), the stirring time is 5 to 10 minutes; Alternatively, in step (2), the drying temperature is 70~75℃ and the time is 1~2 hours; Alternatively, in step (2), the microwave heating treatment time is 10~15min and the microwave power is 800~1000W.

9. The preparation process of the high-strength cement-based mine backfill material containing modified slag as described in any one of claims 1-8, characterized in that, In step (3), the fine aggregate includes at least one of river sand and quartz sand; Alternatively, in step (3), the particle size of the fine aggregate is 1~3mm; Alternatively, in step (3), the fineness of the granulated blast furnace slag powder is 400~500 mesh.

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