An anti-segregation filler and its filling method

Abstract

This invention discloses an anti-segregation filler and its filling method, belonging to the field of mine backfilling technology. The anti-segregation filler is arranged in layers radially along the slurry cross-section, including a dense skeleton layer, an anti-segregation filling layer, and a consolidation layer. The dense skeleton layer is located at the innermost layer of the filler. The anti-segregation filling layer covers the outer periphery of the dense skeleton layer, used to inhibit particle sedimentation and segregation during transportation and to form a uniform and dense filler body after filling. The consolidation layer is located at the outermost layer of the filler, used to form a tight bonding interface with the surrounding rock, thereby sealing the filler and preventing slurry leakage. Furthermore, this invention also proposes a filling method for the above-mentioned anti-segregation filler, which, by setting the dense skeleton layer, anti-segregation filling layer, and consolidation layer, and employing a layered filling process using the same pump and pipe, combined with an adjustable flow guiding device, allows the slurry to spread sequentially in a laminar flow state. The anti-segregation filler proposed in this invention achieves tight consolidation with the surrounding rock interface.

Description

Technical Field

[0001] This invention relates to the field of mine backfilling technology, specifically to an anti-segregation filler and its filling method. Background Technology

[0002] With the increasing depth and intensity of mineral resource extraction, the management of goaf areas in underground mines has become increasingly prominent. Backfilling mining, due to its advantages such as effectively controlling ground pressure, reducing surface subsidence, improving resource recovery rates, and realizing the resource utilization of solid waste such as tailings, has become one of the key technologies for safe and green mining in modern mines.

[0003] Currently, cemented tailings backfilling technology is one of the most widely used backfilling methods. This technology directly mixes the whole tailings (without classification and desliming) discharged from the concentrator with cementing materials and water to prepare backfill slurry, which is then transported through pipelines to the underground goaf for backfilling.

[0004] Existing technologies for material modification and performance optimization in cemented tailings backfill mainly focus on two aspects: first, replacing part of the cement by introducing industrial solid waste or biomass ash to reduce backfilling costs and improve mechanical properties; second, developing new cementitious material systems to improve the rheological or expansive properties of the slurry. For example:

[0005] 1) Patent application CN112284892B discloses a method for improving the compressive strength of cemented tailings fillers by replacing part of the cement with straw ash. In this patent application, the amount of straw ash replacing cement in the method for improving the compressive strength of cemented tailings fillers is 2.5% to 10.0% of the cement mass. This invention, through research on the compressive strength of cemented tailings fillers, selects straw ash, a low-cost and widely available renewable resource, as an admixture to improve the compressive strength of the filler. Uniaxial compressive strength tests were conducted, ultimately yielding a method that can significantly improve the compressive strength of the filler. The increase rate of compressive strength of cemented tailings fillers with straw ash replacing part of the cement compared to fillers with added straw ash was calculated. This method prepares cemented tailings fillers by adding straw ash to replace part of the cement, and its compressive strength is much higher than that of fillers without added straw ash. Furthermore, the amount of cement used is reduced, significantly lowering the filling cost.

[0006] 2) Announcement No. CN117361911B discloses an iron tailings powder-based cementitious material for cemented backfilling of mine tailings, its preparation method, and its application. In this patent application, the polymer-based crack-resistant mortar is made from ultrafine iron tailings powder, mineral powder, sulfoaluminate clinker, silicate cement clinker, desulfurized gypsum, and methyl cellulose ether. This iron tailings powder-based cementitious material can completely replace ordinary silicate cement in whole-tailings backfilling and achieve a better consolidation effect than cement, thereby greatly reducing the consumption of cement and other cementitious materials, lowering backfilling costs, reducing carbon emissions, and increasing tailings utilization. The rheological properties, mechanical properties, and durability of the whole-tailings cemented backfill material made from this iron tailings powder-based cementitious material meet the requirements of mine backfilling, and without the addition of admixtures, it can achieve an expansion and top-joining effect based on its own characteristics, solving the shrinkage problem of cement-based backfill materials.

[0007] In addition, the prior art discloses the following solutions to the problems of stability and anti-segregation of filling slurry during transportation:

[0008] 3) Announcement No. CN107602056B discloses a potash mine backfill material for long-distance gravity-flow transportation and its preparation method. This patent application utilizes solid waste as a binder, while simultaneously co-processing potash mine tailings and tailings liquids, which are currently difficult to comprehensively utilize, thus addressing the environmental impact of potash mine tailings and tailings liquids on the mine. The mass ratio of the components is controlled within the range of: potash mine tailings: potash mine tailings liquid: binder = 55%–83%: 15%–30%: 2%–15%. After mixing and stirring evenly, a potash mine backfill material capable of gravity-flow transportation and meeting the required strength in the later stages can be obtained. The backfill slurry system prepared by this invention is stable, has a reasonable particle size distribution, excellent anti-segregation and anti-bleeding properties, high fluidity, and does not stratify, exhibiting excellent transportation performance. Furthermore, the high concentration of the backfill material enables full-tailings cemented backfilling. The prepared cementitious material undergoes micro-expansion during the hardening process, which is beneficial for the backfill material's connection to the roof.

[0009] Although the aforementioned existing technologies have made some progress in improving the materials and optimizing the performance of cemented tailings backfill, they still have significant limitations when dealing with complex working conditions such as "ultra-long haulage distances, deep wells with high ground pressure, and large-section mining areas," specifically in the following aspects:

[0010] 1. As indicated in announcements CN112284892B and CN117361911B, existing technologies primarily focus on replacing cement by introducing industrial solid waste (such as straw ash and iron tailings powder) or special cementitious materials. The main objectives are to reduce costs and improve individual mechanical properties (such as compressive strength or expansibility). However, these solutions often overlook the rheological and stability balance issues during long-distance pumping. When the filling slurry needs to be pumped for thousands of meters, simply changing the cementitious material system is insufficient to effectively suppress the gravity segregation tendency caused by the wide particle size distribution in the tailings. Furthermore, some modifiers (such as fiber-based or high specific surface area solid waste), while improving strength, often significantly increase the slurry yield stress, thus exacerbating the risk of pipe blockage during long-distance transport.

[0011] 2. Existing tailings filling systems are generally considered homogeneous. However, after long-distance transport and static filling, due to gravity, coarse particles inevitably accumulate at the bottom and center, resulting in an uncontrolled segregation structure within the filler that is "solid at the bottom and loose at the top, coarse inside and fine outside." This heterogeneity prevents the filler from forming an effective load-bearing framework, weakening its support for the goaf. Although announcement number CN107602056B mentions anti-segregation performance, it mainly targets specific salt systems in potash mines, and this system depends on specific tailings salt and tailings liquid components. For metal mine tailings, which are mainly composed of silicate minerals and have a higher particle density, its particle size distribution control mechanism and anti-segregation effect are difficult to directly apply.

[0012] 3. During long-distance transportation, the slurry often stagnates upon arrival at the stope due to kinetic energy decay, resulting in insufficient hydration or severe bleeding at the contact zone between the slurry and the surrounding rock, forming a weak interface. Existing technologies focus primarily on the strength of the filler itself, lacking effective methods for constructing a dense, consolidated layer that can form a chemical-physical dual anchor with the surrounding rock.

[0013] In summary, while existing technologies offer various ways to improve the individual properties of tailings fillers, they lack a comprehensive solution that can address the issues of "non-segregation during long-distance pumping, gradient reinforcement of internal structure, and tight consolidation at the interface with the surrounding rock." Summary of the Invention

[0014] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide an anti-segregation filler and its filling method, solving the technical problem of how to tightly consolidate with the surrounding rock interface in the prior art.

[0015] To achieve the above-mentioned technical objectives, the present invention provides an anti-segregation filler, which is arranged in layers radially along the cross-section of the slurry, including a dense skeleton layer, an anti-segregation filling layer, and a consolidation layer;

[0016] The dense skeleton layer, located at the innermost layer of the infill, is used to provide mechanical support and skeleton load-bearing function for the filled structure;

[0017] The anti-segregation filling layer covers the periphery of the dense skeleton layer and is used to suppress particle sedimentation and segregation during transportation and to form a uniform and dense filling body after filling.

[0018] The consolidation layer, located on the outermost layer of the filler, is used to form a tight bonding interface with the surrounding rock to seal the filler layer and prevent grout leakage.

[0019] In any embodiment, the raw material of the anti-segregation filling layer, by weight, comprises the following components:

[0020] 75-90 parts of fine aggregate from tailings;

[0021] 6-14 parts of the first cementitious material;

[0022] 0.08–1.2 parts of the anti-segregation modifying component;

[0023] Mix with 9 to 18 parts water.

[0024] In any embodiment, the anti-segregation modifying component is one or more of the following: polymeric flocculant, cellulose ether, attapulgite, and silica fume.

[0025] In any embodiment, the polymeric flocculant is anionic polyacrylamide or nonionic polyacrylamide.

[0026] In any embodiment, the raw material of the anti-segregation filling layer further includes 0.05 to 0.7 parts of a plasticizing and flow-enhancing component; the plasticizing and flow-enhancing component is any one of polycarboxylate superplasticizer, naphthalene superplasticizer, and lignin sulfonate superplasticizer.

[0027] In any embodiment, the first cementing material is slag powder or fly ash that has undergone surface hydrophobic modification treatment. The surface hydrophobic modification treatment is obtained by mixing slag powder or fly ash with a silane coupling agent at a mass ratio of 100:0.5 to 2 and stirring at 80 to 120°C for 30 to 60 minutes.

[0028] In any embodiment, the raw material of the consolidation layer is obtained by mixing the hydration product of the second cementitious material and the water-reducing agent at a mass ratio of 100:0.5 to 3; and / or, the thickness of the consolidation layer is 5 to 20 mm.

[0029] In any embodiment, the raw material for the dense skeleton layer is obtained by mixing coarse particles from the tailings with a third cementing material at a mass ratio of 3 to 5:1.

[0030] In any embodiment, the coarse particles in the tailings are particles with a particle size ≥200 mesh, and the third cementing material is one or more of silicate cement, slag powder, fly ash and steel slag powder.

[0031] In addition, the present invention also proposes a filling method for the above-mentioned anti-segregation filler, which involves setting a dense skeleton layer, an anti-segregation filling layer and a consolidation layer, and using a layered filling process with the same pump and the same pipe, combined with an adjustable flow guiding device, so that the slurry is spread out in a laminar flow state.

[0032] Compared with the prior art, the beneficial effects of the present invention include: The present invention provides a segregation-resistant, long-distance transport tailings cemented filler. On the one hand, by constructing a three-layer gradient structure of dense skeleton layer + segregation-resistant filling layer + consolidation layer, it breaks through the limitation of the traditional single homogeneous structure of filler, so that different regions of the filler can undertake the differentiated functions of skeleton support, main body bearing and interface bonding, and achieve tight consolidation with the surrounding rock interface.

[0033] On the other hand, the synergistic effect of anti-segregation modified components and surface hydrophobic modified cementitious materials introduced into the anti-segregation filling layer, combined with the rheological regulation of plasticizing and flow-increasing components, inhibits particle sedimentation, bleeding and stratification of tailings slurry during long-distance transportation from the source.

[0034] In addition, by binding the free water in the slurry and regulating the particle arrangement through anti-segregation modified components, and at the same time using cementitious materials that have undergone surface hydrophobic modification, the hydration reaction rate is slowed down, the consumption of free water is reduced, and the water retention of the slurry is enhanced. The synergistic effect of the two avoids the problems of bleeding, stratification, and segregation of the slurry during transportation in pipelines thousands of meters long from the source.

[0035] This invention features a dense skeleton layer in the central region of the filler, composed of coarse tailings particles and cementing materials at a mass ratio of 3–5:1, providing high-strength mechanical support and load-bearing capacity. The outer layer consists of an anti-segregation filling layer, forming a uniform and dense filler body. The outermost layer forms a tightly bonded interface with the surrounding rock through a consolidation layer. The synergistic effect of these three layers significantly improves the overall compressive strength of the filler compared to traditional homogeneous fillers.

[0036] This invention does not rely on a specific type of tailings or cementitious material system and can be widely applied to the backfilling of tailings in metal mines. By using industrial solid wastes such as slag powder and fly ash as the main cementitious material and improving its performance through surface hydrophobic modification treatment, the amount of high-cost cementitious materials such as cement is reduced, effectively lowering the backfilling cost while ensuring the performance of the filler. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the radially layered structure of the filler in Embodiments 1-3 of the present invention;

[0038] Figure 2 This is a schematic diagram of the process sequence for the layered filling of the filler in Embodiments 1-3 of the present invention, using the same pump and pipe for each layer.

[0039] Figure 3 These are on-site construction photos of the filler material for Example 3.

[0040] Figure 4 These are on-site construction photos of the filler material for Example 3.

[0041] Explanation of reference numerals in the attached figures:

[0042] 1. Dense skeleton layer; 2. Anti-segregation filling layer; 3. Consolidation layer. Detailed Implementation

[0043] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0044] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0045] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0046] This specific embodiment provides an anti-segregation filler, which is arranged in layers along the radial direction of the slurry cross section, including a dense skeleton layer, an anti-segregation filling layer and a consolidation layer;

[0047] The dense skeleton layer, located at the innermost layer of the filler, is used to provide mechanical support and skeleton load-bearing function for the filler;

[0048] The anti-segregation filling layer covers the periphery of the dense skeleton layer and is used to suppress particle sedimentation and segregation during transportation and to form a uniform and dense filling body after filling.

[0049] The consolidation layer, located on the outermost layer of the filler, is used to form a tight bonding interface with the surrounding rock to seal the filler and prevent grout leakage.

[0050] In some embodiments, the raw material of the anti-segregation filler layer comprises, by weight, the following components:

[0051] 75-90 parts of fine aggregate from tailings;

[0052] 6-14 parts of the first cementitious material;

[0053] 0.08–1.2 parts of the anti-segregation modifying component;

[0054] Mixing water: 9-18 parts;

[0055] The anti-segregation modifying component is one or more of the following: a polymeric flocculant, a cellulose ether, attapulgite, and silica fume; the polymeric flocculant is anionic polyacrylamide or nonionic polyacrylamide; the first cementing material is slag powder or fly ash that has undergone surface hydrophobic modification treatment. The surface hydrophobic modification treatment is obtained by mixing slag powder or fly ash with a silane coupling agent at a mass ratio of 100:0.5-2 and stirring at 80-120°C for 30-60 minutes.

[0056] In some embodiments, the raw material of the anti-segregation filling layer further includes 0.05 to 0.7 parts of a plasticizing and flow-enhancing component; the plasticizing and flow-enhancing component is any one of polycarboxylate superplasticizer, naphthalene superplasticizer, and lignin sulfonate superplasticizer; the plasticizing and flow-enhancing component is added in two parts during the stirring process, with 60% to 80% added in the first part and the remaining part added 1 to 2 minutes before the end of stirring.

[0057] In some embodiments, the raw material of the consolidation layer is obtained by mixing the hydration product of the second cementitious material and the water-reducing agent at a mass ratio of 100:0.5 to 3; the raw material of the dense skeleton layer is obtained by mixing coarse particles from the tailings and the third cementitious material at a mass ratio of 3 to 5:1; the coarse particles in the tailings are particles with a particle size ≥200 mesh, and the cementitious material is one or more of silicate cement, slag powder, fly ash, and steel slag powder; the thickness of the consolidation layer is 5 to 20 mm.

[0058] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0059] In this invention, the terms "some embodiments," "this embodiment," and examples are used to describe a subset of all possible embodiments. However, it is understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.

[0060] If the application documents contain similar descriptions such as "first / second", the following explanation shall be added: In the following description, the terms "first / second / third" are used only to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0061] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, object A and / or object B can represent three situations: object A exists alone, object A and object B exist simultaneously, and object B exists alone.

[0062] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0063] Example 1

[0064] Combination Figure 1 This embodiment provides an anti-segregation filler that is placed inside the goaf formed by underground mining and used to construct a dense filling structure. The filler is arranged in layers along the radial direction of the slurry cross section, including a dense skeleton layer 1, an anti-segregation filling layer 2, and a consolidation layer 3.

[0065] Based on the above embodiments, in this embodiment, the dense skeleton layer 1 is located at the innermost layer of the filler. It is formed by enriching the coarse particles from the tailings with the third cementing material in the central region of the filler at a mass ratio of 4:1, and is used to provide mechanical support and skeleton load-bearing function for the filling structure. The coarse particles in the tailings are particles with a particle size ≥200 mesh, and the third cementing material is silicate cement.

[0066] Based on the above embodiments, in this embodiment, the anti-segregation filling layer 2 is wrapped around the dense skeleton layer 1 to suppress particle sedimentation and segregation during transportation and to form a uniform and dense filling body after filling; the raw material of the anti-segregation filling layer is conventional tailings slurry filling.

[0067] Based on the above embodiments, the consolidation layer 3 in this embodiment is located on the outermost layer of the filler and is in contact with the surrounding rock of the goaf. It is used to form a tight bonding interface with the surrounding rock to seal the filler and prevent grout leakage. The raw material of the consolidation layer is obtained by mixing the hydration product of the second cementing material and the water-reducing agent at a mass ratio of 100:2. The second cementing material is slag powder that has undergone surface hydrophobic modification treatment. The surface hydrophobic modification treatment is obtained by mixing slag powder with silane coupling agent (KH-570, i.e., γ-methacryloyloxypropyltrimethoxysilane) at a mass ratio of 100:1.5 and stirring at 120°C for 30 minutes. The raw material of the dense skeleton layer is obtained by mixing coarse particles from the tailings and the third cementing material at a mass ratio of 4:1. The coarse particles from the tailings are particles with a particle size ≥200 mesh, and the third cementing material is silicate cement. The thickness of the consolidation layer is 15 mm.

[0068] Based on the above embodiments, in this embodiment, the anti-segregation filling layer 2, the dense skeleton layer 1 and the consolidation layer 3 adopt the same pump and the same pipe for layered filling process. An adjustable flow guiding device is set at the filling pipe opening so that the slurry spreads in a laminar flow state in sequence, ensuring that the interlayer interface is fused without weak surfaces.

[0069] Combination Figure 2 This embodiment proposes a three-layer gradient structure for anti-segregation, long-distance transport of fully cemented tailings filler. By setting up a dense skeleton layer 1, an anti-segregation filling layer 2, and a consolidation layer 3, and employing a layered filling process using the same pump and pipe, coupled with an adjustable flow guiding device, the slurry spreads sequentially in a laminar flow state. This embodiment achieves structural gradient differentiation within the filler: the central dense skeleton layer 1 provides mechanical support, the outer consolidation layer 3 forms a tight bond with the surrounding rock, and the middle layer serves as the main filling material. This structural design achieves differentiated functional allocation in different areas of the filler, meeting the comprehensive performance requirements of the goaf for central load-bearing capacity, peripheral enclosure, and overall uniformity of the filler.

[0070] Example 2

[0071] Combination Figure 1 This embodiment provides an anti-segregation filler that is placed inside the goaf formed by underground mining and used to construct a dense filling structure. The filler is arranged in layers along the radial direction of the slurry cross section, including a dense skeleton layer 1, an anti-segregation filling layer 2, and a consolidation layer 3.

[0072] Based on the above embodiments, in this embodiment, the dense skeleton layer 1 is located at the innermost layer of the filler. It is formed by enriching the coarse particles from the tailings with the third cementing material in a mass ratio of 3:1 in the central region of the filler, and is used to provide mechanical support and skeleton load-bearing function for the filling structure. The coarse particles in the tailings are particles with a particle size ≥200 mesh, and the third cementing material is silicate cement.

[0073] Based on the above embodiments, in this embodiment, the anti-segregation filling layer 2 covers the periphery of the dense skeleton layer 1, and is used to inhibit particle sedimentation and segregation during transportation and to form a uniform and dense filling body after filling; the raw material of the anti-segregation filling layer, by weight, includes the following components:

[0074] 79 parts of fine aggregate from tailings;

[0075] 12 parts of the first cementitious material;

[0076] 0.2 parts of anti-segregation modifier;

[0077] 11 parts mixing water;

[0078] The anti-segregation modifying component is a polymeric flocculant; the polymeric flocculant is anionic polyacrylamide; the first cementing material is mineral fly ash that has undergone surface hydrophobic modification treatment. The surface hydrophobic modification treatment is prepared by mixing fly ash with a silane coupling agent (KH-570, i.e., γ-methacryloyloxypropyltrimethoxysilane) at a mass ratio of 100:1.5 and stirring at 120°C for 30 minutes.

[0079] Based on the above embodiments, the consolidation layer 3 in this embodiment is located at the outermost layer of the filling structure and is in contact with the surrounding rock of the goaf. It is used to form a tight bonding interface with the surrounding rock to seal the filler and prevent grout leakage. The raw material of the consolidation layer is obtained by mixing the hydration product of the second cementing material and the water-reducing agent at a mass ratio of 100:3. The second cementing material is the same as the first cementing material (mineral powder and fly ash with surface hydrophobic modification treatment). The raw material of the dense skeleton layer is obtained by mixing the coarse particles in the tailings and the third cementing material at a mass ratio of 5:1. The coarse particles in the tailings are particles with a particle size ≥200 mesh, and the third cementing material is steel slag powder. The thickness of the consolidation layer is 15 mm.

[0080] Based on the above embodiments, in this embodiment, the anti-segregation filling layer 2, the dense skeleton layer 1 and the consolidation layer 3 adopt the same pump and the same pipe for layered filling process. An adjustable flow guiding device is set at the filling pipe opening so that the slurry spreads in a laminar flow state in sequence, ensuring that the interlayer interface is fused without weak surfaces.

[0081] In actual long-distance transportation conditions, the residence time of the filling slurry in the pipeline increases significantly with the increase of transportation distance and elevation difference. For deep mines with transportation distances exceeding 2000 meters and elevation differences greater than 300 meters, the residence time of the slurry in the pipeline usually exceeds 1.5 hours. During this process, the slurry is affected by continuous shearing and the consumption of free water by hydration reactions. If its plastic flow time is less than 1 hour, it is difficult to maintain the spreading performance after reaching the stope, and the filler may not be uniformly distributed due to the decrease in fluidity. Therefore, based on Example 1, Example 2 further optimizes the raw material composition and performance parameters of each component of the anti-segregation filling layer 2, so that the filler effectively improves the stability of the slurry and the uniformity of the filler through the synergistic effect of gradation optimization and hydrophobic modified cementitious materials, providing a material basis for adapting to the transportation needs of longer time and longer distances.

[0082] Example 3

[0083] Combination Figure 1 This embodiment provides an anti-segregation filler that is placed inside the goaf formed by underground mining and used to construct a dense filling structure. The filler is arranged in layers along the radial direction of the slurry cross section, including a dense skeleton layer 1, an anti-segregation filling layer 2, and a consolidation layer 3.

[0084] Based on the above embodiments, in this embodiment, the dense skeleton layer 1 is located at the innermost layer of the filler. It is formed by enriching the coarse particles from the tailings with the third cementing material in the central region of the filler at a mass ratio of 4:1, and is used to provide mechanical support and skeleton load-bearing function for the filling structure. The coarse particles in the tailings are particles with a particle size ≥200 mesh, the third cementing material is silicate cement, and the thickness of the consolidation layer is 15 mm.

[0085] Based on the above embodiments, in this embodiment, the anti-segregation filling layer 2 covers the periphery of the dense skeleton layer 1, and is used to inhibit particle sedimentation and segregation during transportation and to form a uniform and dense filling body after filling; the raw material of the anti-segregation filling layer, by weight, includes the following components:

[0086] 79 parts of fine aggregate from tailings;

[0087] 12 parts of the first cementitious material;

[0088] 0.2 parts of anti-segregation modifier;

[0089] 0.1 parts of the plasticizing and flow-enhancing component;

[0090] 11 parts mixing water;

[0091] The anti-segregation modifying component is a polymeric flocculant; the polymeric flocculant is anionic polyacrylamide; the plasticizing and flow-enhancing component is a polycarboxylate-based high-efficiency water-reducing agent; the first cementing material is fly ash that has undergone surface hydrophobic modification treatment. The surface hydrophobic modification treatment is prepared by mixing slag powder or fly ash with a silane coupling agent (KH-570, i.e., γ-methacryloyloxypropyltrimethoxysilane) at a mass ratio of 100:1.5 and stirring at 120°C for 30 minutes; the plasticizing and flow-enhancing component is added in two parts during the stirring process, with 70% added first and the remaining part added 1.5 minutes before the end of stirring to optimize adsorption distribution and prolong plasticity retention time.

[0092] Based on the above embodiments, the consolidation layer 3 in this embodiment is located at the outermost layer of the filling structure and is in contact with the surrounding rock of the goaf. It is used to form a tight bonding interface with the surrounding rock to seal the filler and prevent grout leakage. The raw material of the consolidation layer is obtained by mixing the hydration product of the second cementing material (the same as the first cementing material) and the water-reducing agent at a mass ratio of 100:3. The raw material of the dense skeleton layer is obtained by mixing the coarse particles in the tailings and the third cementing material at a mass ratio of 5:1. The coarse particles in the tailings are particles with a particle size ≥200 mesh, and the cementing material is steel slag powder. The thickness of the consolidation layer is 15 mm.

[0093] Based on the above embodiments, in this embodiment, the anti-segregation filling layer 2, the dense skeleton layer 1 and the consolidation layer 3 adopt the same pump and the same pipe for layered filling process. An adjustable flow guiding device is set at the filling pipe opening so that the slurry spreads in a laminar flow state in sequence, ensuring that the interlayer interface is fused without weak surfaces.

[0094] This embodiment proposes a three-layer gradient structure for anti-segregation, long-distance transport, and cemented tailings backfilling. By setting up a dense skeleton layer 1, an anti-segregation backfill layer 2, and a consolidation layer 3, and employing a layered backfilling process using the same pump and pipe, coupled with an adjustable flow guiding device, the slurry spreads sequentially in a laminar flow state. This embodiment achieves structural gradient differentiation within the backfill: the central dense skeleton layer 1 provides mechanical support, the outer consolidation layer 3 forms a tight bond with the surrounding rock, and the middle layer serves as the main backfill material. This structural design achieves differentiated functional allocation in different areas of the backfill, meeting the comprehensive performance requirements of the goaf for central load-bearing capacity, peripheral enclosure, and overall uniformity of the backfill.

[0095] When the conveying distance is extended to over 3000 meters or the pumping pressure fluctuates significantly, relying solely on anti-segregation modified components and gradation optimization is insufficient to fully meet the stringent requirements for slurry plasticity retention time during long-distance pumping. In practical engineering, the shearing action of the slurry in the pipeline accelerates the collision and hydration of cementitious particles, leading to faster consumption of free water and increased yield stress, resulting in fluidity reduction before reaching the stope. If a plastic flow duration of at least 2 hours cannot be maintained, the slurry will struggle to spread sufficiently within the goaf, potentially causing pipeline blockage. Therefore, Example 3, based on Example 2, further introduces plasticity-preserving and flow-enhancing components and a two-stage addition process, effectively adapting the solution to ultra-long-distance, deep-well, high-pressure pipeline pumping conditions. Simultaneously, it forms a synergistic system of anti-segregation, plasticity preservation, and flow enhancement with the anti-segregation modified components and hydrophobic modified cementitious materials, achieving dual optimization of long-distance conveying stability and filler curing performance. Figure 3 and Figure 4 These are on-site construction photos of the filler material for Example 3.

[0096] To verify the technical effectiveness of the anti-segregation, long-distance transport tailings cemented filler provided in Examples 1, 2, and 3, comparative tests were conducted with reference to the standards and test conditions in Table 1 below:

[0097] Table 1

[0098] Slump test GB / T 50080-2016 Standard for Test Methods of Performance of Ordinary Concrete Mixtures Water exudation rate test GB / T 50080-2016 Standard for Test Methods of Performance of Ordinary Concrete Mixtures Compressive strength test GB / T 50081-2019 Standard for Test Methods of Physical and Mechanical Properties of Concrete Bond strength between filler and surrounding rock GB / T 50448-2015 Technical Specification for Application of Cement-Based Grouting Materials (Refer to Bond Strength Test Method) Slurry segregation rate Refer to the segregation resistance test method (wet sieve method) in JGJ / T 283-2012 "Technical Specification for Application of Self-Compacting Concrete".

[0099] Experimental conditions:

[0100] Ambient temperature: 20℃±2℃;

[0101] Relative humidity: 60%±5%;

[0102] Maintenance conditions: Standard maintenance (temperature 20℃±1℃, relative humidity ≥95%), maintenance period 28 days;

[0103] Simulated pipeline parameters: pipe diameter DN100, conveying distance 3000m (horizontal section 2400m + vertical section 600m), conveying pressure 1.2~1.8MPa;

[0104] Pumping equipment: S-valve piston concrete pump, pumping capacity 40m³ / h 3 / h;

[0105] Goaf simulation mold: A self-made steel mold (inner diameter 500mm×500mm×500mm) was used, with the inner wall lined with field-collected surrounding rock test blocks to simulate the actual contact interface. The filling conditions of each embodiment and control group are shown in Table 2, and the conveying performance test results are shown in Table 3.

[0106] Table 2

[0107] control group Traditional homogeneous tailings cemented filler Experimental Group A In Example 1, there is a three-layer structure (the middle layer is filled with conventional tailings slurry). Experimental Group B Components in Example 2 (without plasticizing and flow-enhancing components) Experimental group C Example 3 Complete Components (including anti-segregation modified components + plasticizing and flow-enhancing components + hydrophobic modified cementitious materials)

[0108] Table 3

[0109] Initial slump (mm) 265 260 255 270 Slump at the end of the conveying process (mm) 182 210 235 262 Slump loss rate (%) 31.3 19.2 7.8 3.0 Segregation rate (%, wet sieving method) 24.6 15.3 5.2 1.8 Water exudation rate (%) 8.2 5.1 2.3 0.6 Plastic flow duration (h) 0.8 1.0 1.2 2.5

[0110] The segregation rate was determined by wet sieving: about 5 kg of slurry from the pipeline outlet was wet-sieved using a 0.3 mm standard sieve, and the absolute value of the deviation between the mass ratio of coarse particles on the sieve and the theoretical mass ratio of coarse particles in the design mix was calculated. The mechanical property test results of the filler (standard curing for 28 days) are shown in Table 4.

[0111] Table 4

[0112] Uniaxial compressive strength (MPa) 2.8 3.5 4.6 5.8 Central region compressive strength (MPa) 3.2 4.8 6.2 7.5 Edge region compressive strength (MPa) 2.4 2.9 3.5 4.2 Intensity dispersion coefficient (CV, %) 18.6 21.4 16.8 12.3 Bond strength with surrounding rock (MPa, 28d) 0.6 1.1 1.2 1.5

[0113] The experimental results show that after a 3000m long-distance transport, experimental group C (Example 3) exhibited a slump loss rate of only 3.0%, a segregation rate of only 1.8%, a bleeding rate of only 0.6%, and a plastic flow duration of 2.5 hours. All transport performance indicators were significantly superior to those of the control group, experimental group A, and experimental group B, verifying the synergistic effect of the anti-segregation modifier and the plastic-retaining and flow-enhancing component. The 28-day uniaxial compressive strength of experimental group C reached 5.8 MPa, an increase of 107% compared to the control group; the strength dispersion coefficient was only 12.3%, far lower than the 18.6% of the control group, indicating a significant improvement in filler uniformity. Comparing experimental groups B and C, it can be seen that the introduction of the plastic-retaining and flow-enhancing component increased the plastic flow duration from 1.2 hours to 2.5 hours, reduced the segregation rate from 5.2% to 1.8%, and reduced the bleeding rate from 2.3% to 0.6%, indicating a synergistic effect between the plastic-retaining and flow-enhancing component and the anti-segregation modifier.

[0114] It should be noted that the silane coupling agents used in the surface hydrophobic modification treatment in Examples 1, 2, and 3 above can be one or more of the following: silane coupling agents having unsaturated double bonds, long-chain alkyl groups, or capable of undergoing condensation reactions with hydroxyl groups on the surface of the cementitious material. Exemplarily, these include, but are not limited to, γ-methacryloyloxypropyltrimethoxysilane (KH-570), γ-aminopropyltriethoxysilane (KH-550), γ-glycidyl etheroxypropyltrimethoxysilane (KH-560), and vinyltriethoxysilane (A-151).

[0115] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An anti-segregation filler, characterized in that, The material is arranged in layers radially along the cross-section of the slurry, including a dense skeleton layer, an anti-segregation filling layer, and a consolidation layer; The dense skeleton layer, located in the innermost layer of the infill, is used to provide mechanical support and skeleton load-bearing function for the filled structure; The anti-segregation filling layer covers the periphery of the dense skeleton layer and is used to suppress particle sedimentation and segregation during transportation and to form a uniform and dense filling body after filling. The consolidation layer, located on the outermost layer of the filler, is used to form a tight bonding interface with the surrounding rock to seal the filler layer and prevent grout leakage.

2. The anti-segregation filler according to claim 1, characterized in that, The raw material for the anti-segregation filling layer, by weight, includes the following components: 75-90 parts of fine aggregate from tailings; 6-14 parts of the first cementitious material; 0.08–1.2 parts of the anti-segregation modifying component; Mix with 9 to 18 parts water.

3. The anti-segregation filler according to claim 2, characterized in that, The anti-segregation modifying component is one or more of the following: polymeric flocculant, cellulose ether, attapulgite, and silica fume.

4. The anti-segregation filler according to claim 3, characterized in that, The polymeric flocculant is anionic polyacrylamide or nonionic polyacrylamide.

5. The anti-segregation filler according to claim 2, characterized in that, The raw material of the anti-segregation filling layer also includes 0.05 to 0.7 parts of a plasticizing and flow-enhancing component; the plasticizing and flow-enhancing component is any one of polycarboxylate-based high-efficiency water-reducing agent, naphthalene-based water-reducing agent, and lignin sulfonate water-reducing agent.

6. The anti-segregation filler according to claim 2, characterized in that, The first cementing material is slag powder or fly ash that has undergone surface hydrophobic modification. The surface hydrophobic modification is achieved by mixing slag powder or fly ash with a silane coupling agent at a mass ratio of 100:0.5 to 2 and stirring at 80 to 120°C for 30 to 60 minutes.

7. The anti-segregation filler according to claim 1, characterized in that, The raw material of the consolidation layer is obtained by mixing the hydration product of the second cementitious material and the water-reducing agent at a mass ratio of 100:0.5 to 3; and / or, the thickness of the consolidation layer is 5 to 20 mm.

8. The anti-segregation filler according to claim 1, characterized in that, The raw material for the dense skeleton layer is obtained by mixing coarse particles from the tailings with a third cementing material at a mass ratio of 3 to 5:

1.

9. The anti-segregation filler according to claim 8, characterized in that, The coarse particles in the tailings are particles with a particle size ≥200 mesh, and the third cementing material is one or more of silicate cement, slag powder, fly ash and steel slag powder.

10. The method for filling the anti-segregation filler according to any one of claims 1-9, characterized in that, By setting up a dense skeleton layer, an anti-segregation filling layer and a consolidation layer, and using a layered filling process with the same pump and pipe, combined with an adjustable flow guiding device, the slurry is spread out in a laminar flow state.

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