Comprehensive supporting method utilizing magnetite in mining area

Abstract

The invention provides a comprehensive supporting method using magnetite in a mining area. The comprehensive supporting method comprises the steps that anchor rod drilling is conducted, specifically, drilling is conducted on a slope according to the designed interval and depth; an anchor rod is manufactured and installed, specifically, the anchor rod is made of steel, the length of the anchor rod is determined according to the depth of a drilled hole, waste magnetite in a mining area is ground into particles, the magnetite particles are mixed with a binding material, and magnetic mixed slurry with magnetism is manufactured; the anchor rod is inserted into the drill hole, and then the mixed magnetic mixed grout is injected into the drill hole through the grouting pipe; and fixing and tensioning the anchor rod: after the magnetic mixed slurry is solidified, applying tensile force by using a special anchor rod tension meter, tensioning the anchor rod, and fixing the end part of the tensioned anchor rod through a base plate and a nut. According to the method, the waste magnetite is utilized, the anchoring force of the anchor rod and the anchor cable and the bonding force of mortar are improved through magnetic force, the structural stability and durability are enhanced, and the environment-friendly benefit and the self-adaptive deformation capacity are both achieved.

Description

Technical Field

[0001] The invention relates to the field of geotechnical engineering, and relates to a comprehensive support method utilizing magnetite in a mining area. Background Art

[0002] In traditional mining operations, ore mining mainly focuses on extracting valuable metal components, such as extracting iron from magnetite. A large amount of magnetite is sent to the beneficiation plant for complex processing. In this process, low-grade magnetite or slag produced during mining and beneficiation is often regarded as waste or simply piled up. This not only occupies a large amount of land resources, but may also cause environmental pollution and other problems due to improper stacking.

[0003] Traditional anchor support mainly relies on the bonding force of grouting materials and the mechanical bite of anchors and rocks. Under some special geological conditions, such as weak surrounding rock or broken rock mass, its anchoring effect may not be ideal.

[0004] As society pays more and more attention to environmental protection and safe production, mining areas need to take more effective measures to reduce the impact on the environment and ensure the safety of workers during mining and operation. Slope instability will not only lead to production interruptions in mining areas, but may also cause serious geological disasters such as landslides, posing a threat to surrounding residents and facilities. Therefore, the development of an efficient, environmentally friendly and economical slope support method has become an urgent need for the sustainable development of mining areas. Using the mine's own magnetite resources for slope support can not only reduce waste emissions, but also improve the stability of the slope, meeting the dual requirements of environmental protection and safety. Summary of the invention

[0005] In order to solve the current technical problems, the main purpose of the present invention is to provide a comprehensive support method using magnetite in mining areas. By utilizing the ready-made magnetite in the mining area, magnetic slurry is produced on-site, and the magnetic field contained in the mining area is used to better adsorb the slurry, thereby saving costs and increasing the stability of the slope.

[0006] In order to realize the above technical features, the object of the present invention is achieved as follows: a comprehensive support method using magnetite in a mining area, comprising the following steps: When using bolting in conjunction with magnetite applications: Step 1.1, anchor drilling: Drill holes on the slope at designed spacing and depth; Step 1.2, anchor rod production and installation: The anchor rod is made of steel, and its length is determined according to the depth of the borehole. The magnetite abandoned in the mining area is ground into particles, and the magnetite particles are mixed with a bonding material to make a magnetic mixed slurry with magnetic properties. The anchor rod is inserted into the borehole, and then the mixed magnetic mixed slurry is injected into the borehole through a grouting pipe. Step 1.3, anchor bolt fixing and tightening: After the magnetic mixed slurry solidifies, a special anchor tensile gauge is used to apply tension to tighten the anchor. The tightened anchor ends are fixed with pads and nuts.

[0007] The drilling diameter is between 30mm and 100mm; During the drilling process, the verticality of the borehole must be maintained and the deviation should be controlled within a certain range, usually not exceeding 3% of the drilling depth.

[0008] The length of the anchor rod is 0.2m-0.5m longer than the depth of the drilling hole, and has a certain tensile strength and surface roughness to facilitate the attachment to the magnetic mixed slurry.

[0009] The magnetite particles have a particle size range of 2 mm to 10 mm, are magnetic, and account for 10% to 30% of the volume of the magnetic mixed slurry; The bonding material includes cement and sand, wherein the volume ratio of cement to sand is 1:1-1:3. The bonding material is mixed with magnetite particles to form a magnetic mixed slurry with viscosity and plasticity. The magnetic mixed slurry can provide sufficient compressive strength and bonding force after solidification, and due to the magnetism of the magnetite particles, it generates additional adsorption force with the surrounding rocks and anchor rods.

[0010] The magnetite particles are evenly distributed in the magnetic mixed slurry, and when the slope rock and soil body undergoes slight deformation, the magnetic mixed slurry maintains a relatively stable connection with the rock wall and the anchor by means of the magnetism of the magnetite, thereby reducing the risk of anchor failure; A trace amount of waterproofing agent and retarder are also added to the magnetic mixed slurry as additives to improve the performance of the magnetic mixed slurry and adapt to different slope geological conditions and construction environments.

[0011] In step 1.2, the grouting pipe is placed in the borehole along one side of the anchor rod. During the grouting process, the anchor rod is wrapped by the flow of the magnetic mixed slurry, so that the magnetic mixed slurry is in full contact with the anchor rod. Due to the presence of magnetite particles in the magnetic mixed slurry, when the magnetic mixed slurry wraps the anchor rod, the magnetic property of the magnetite will enhance the bonding force with the anchor rod.

[0012] The tension applied in step 1.3 is determined according to the design bearing capacity of the anchor rod, and the tension is required to reach 70%-90% of the design tension of the anchor rod; The area of ​​the pad should be large enough to disperse the tension of the anchor rod and prevent local rocks from being crushed; the size of the pad is calculated based on the tension of the anchor rod and the compressive strength of the rock, and the diameter is between 100mm-300mm.

[0013] A comprehensive support method using magnetite in a mining area comprises the following steps: Retaining wall reinforcement and magnetite utilization: Step 2.1, retaining wall foundation treatment: Dig the foundation pit of the retaining wall, and lay the foundation with a magnetite crushed stone cushion layer with a particle size of 10mm-30mm. The depth and width are determined according to the height of the retaining wall and geological conditions; Step 2.2, the retaining wall adopts a concrete structure, and a certain proportion of magnetite particles are added to the concrete; the particle size of the magnetite particles is selected between 0.075mm-0.5mm, and the addition amount accounts for 5%-15% of the total volume of the concrete, and drainage holes are set at intervals of 1m-3m.

[0014] In the retaining wall reinforcement and magnetite utilization steps, the density of the concrete wall containing magnetite particles is increased by 5%-10% compared with that of the ordinary concrete wall.

[0015] A comprehensive support method using magnetite in a mining area comprises the following steps: When supporting prestressed anchor cables and magnetic mixed mortar containing expansion agent in mine tunnels: Step 3.1, preliminary preparation: Prepare prestressed anchor cable materials, select high-strength, low-relaxation steel strands, and determine them according to the designed anchoring force. At the same time, prepare matching anchors and pad accessories. The anchors must meet the corresponding anchoring performance standards. The pad thickness is not less than 10mm, and the area is determined based on the anchor cable tension and the surrounding rock compressive strength to effectively disperse the anchor cable tension; prepare magnetic mixed mortar, and the particle size of magnetite is 2mm-10mm; cement, ordinary silicate cement is used; sand, medium-coarse sand is selected, and the mud content does not exceed 3%, and large particles and fine powder are removed after screening; the expansion agent is selected according to the characteristics of the mine surrounding rock and the project requirements, and its dosage is 8%-15% of the cement mass; admixtures, prepare appropriate amounts of water reducer and early strength agent; Step 3.2, anchor cable drilling and installation: According to the pre-planned layout, use the total station to accurately determine the location of each prestressed anchor cable drill hole on the mine wall; use drilling equipment to drill holes according to the designed angle and depth; cut the steel strands according to the designed length to ensure that the length error is within ±5cm; install positioning brackets on the anchor cable to ensure that the anchor cable is centered in the drill hole. The spacing between the positioning brackets is 1m-2m. Slowly insert the anchor cable into the drill hole. The insertion depth meets the design requirements. The exposed length is 0.5m-1m for subsequent tensioning operations; Step 3.3, preparation and pouring of magnetic mixed mortar: According to the designed proportion, cement, sand, magnetite particles, expansion agent, water reducing agent and early strength agent are added to the mixer in sequence, and a water-cement ratio of 0.4-0.6 is adopted, so that the magnetic mixed mortar can meet the grouting requirements and ensure the strength development; the mixed magnetic mixed mortar is injected into the anchor cable borehole through the grouting pipe, and the grouting pipe is inserted into the bottom of the borehole, and the grouting is performed from bottom to top; when a large amount of uniform grouting appears at the hole mouth and the grouting pressure is stable, the grouting is suspended, and the grouting is repeated after waiting for a few seconds until the hole mouth no longer returns grouting and the grouting pressure is stable above the designed value, indicating that the borehole is full of magnetic mixed mortar; Step 3.4, anchor cable tensioning and locking: After the magnetic mixed mortar is poured, wait for enough time for the magnetic mixed mortar to solidify according to the solidification characteristics of the mortar; use the anchor tensioning equipment to tension the solidified anchor cable, and after reaching the specified tension, keep the tension stable for a few seconds, and then install the anchor clip to lock the anchor cable.

[0016] The present invention has the following beneficial effects: 1. Compared with traditional anchor support, the present invention mainly relies on the bonding force and mechanical bite of grouting materials. After adding magnetite, it is equivalent to adding a new force mode, namely magnetic force. Due to the presence of magnetite, the magnetic grouting material can be better adsorbed on the surrounding rock wall in the borehole, and can provide additional friction after solidification. Due to the magnetic attraction between magnetite particles and ferromagnetic minerals in the surrounding rocks, the bonding force between the anchor and the rock is enhanced.

[0017] 2. The present invention utilizes the magnetite resources in the mining area itself for anchor support, which reduces the demand for external support materials and avoids the energy consumption and environmental pollution caused by mining and transportation of external materials; at the same time, it rationally utilizes the ore resources in the mining area, reduces the stacking of magnetite waste, and reduces the risk of pollution to surrounding land and water bodies.

[0018] 3. Compared with traditional slope support, the present invention has the ability to adapt to slope deformation. When the slope rock and soil undergo slight displacement or deformation, due to the magnetic effect of magnetite, the grouting material around the anchor rod can adaptively adjust to a certain extent as the rock and soil deforms. This is because the existence of magnetic force can maintain the connection between particles within a certain range, and it will not crack or fall off as easily as ordinary grouting materials.

[0019] 4. The present invention uses magnetite particles mixed with cement slurry and other bonding materials to make a magnetic grouting material that has the characteristics of self-aggregation, not easy to disperse in water and attracted by magnetic force, so it can squeeze (discharge) groundwater and gas to the maximum extent during construction.

[0020] 5. The present invention utilizes magnetite particles to fill the gaps in the bonding material, making the structure of the grouting material more compact and improving the material stability and durability; during the solidification process of the material, due to the presence of magnetic force, the relative positions between the particles are more stable, reducing the internal defects caused by material shrinkage and deformation.

[0021] 6. The present invention can be used for magnetite utilization and retaining wall reinforcement. The retaining wall adopts a concrete structure, and a certain proportion of magnetite powder is added to the concrete. After the concrete is poured to form the wall, the density of the wall is improved due to the presence of the magnetite powder. At the same time, the magnetism also helps to absorb the surrounding iron-containing magnetic particles and enhance the integrity of the wall.

[0022] 7. The present invention can be used for support in mines using prestressed anchor cables and magnetic mixed mortar containing expansion agents. Since the magnetite component in the magnetic mixed mortar can make it have a certain magnetism, in some mines with weak magnetism, this magnetism can make the mortar better adhere to the surface of the surrounding rock, thereby improving the support effect.

[0023] 8. The present invention can also act directly on the cracks. In the absence of anchor rods, the insertion grouting method can be directly adopted. Single-liquid grouting can be used, and a curing agent can be used for adjustment; double-liquid grouting can also be used, and water glass can be used as a binder for adjustment. Due to the magnetic properties of the magnetic mixed slurry, it produces a magnetic attraction effect with the magnetic minerals in the mine, which can fill the cracks more quickly and conveniently. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0025] Figure 1 It is a schematic diagram of the anchor rod of the present invention on a slope containing magnetite.

[0026] Figure 2 It is a schematic diagram of grouting through a grouting pipe according to the present invention.

[0027] Figure 3 These are comparison diagrams of the bonding interfaces of the anchor rod of the present invention with ordinary mortar and magnetic mixed slurry respectively.

[0028] Figure 4 It is a schematic diagram of the retaining wall reinforcement of the present invention.

[0029] Figure 5 It is a schematic diagram of the prestressed anchor cable in a mine tunnel according to the present invention.

[0030] In the figure: anchor rod 1, grouting pipe 2, tensioning pad 3, nut 4, tensioning base 5, slope containing magnetite 6, magnetic mixed slurry 7, ordinary slurry 8, magnetite crushed stone cushion 9, retaining wall containing magnetic mixed mortar 10, drainage hole 11, mine cave 12, prestressed anchor cable 13. DETAILED DESCRIPTION

[0031] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0032] Embodiment 1: See also Figure 1-3 , a comprehensive support method using magnetite in a mining area, comprising the following steps: When bolt support is combined with magnetite application: Step 1: Anchor drilling. Drill holes on the slope according to the designed spacing and depth. The diameter and depth of the holes are determined according to the specific geological conditions and support requirements of the slope. Generally speaking, the diameter of the holes can be between 30-100mm, and the depth may range from several meters to tens of meters.

[0033] During the drilling process, attention should be paid to maintaining the verticality of the drilled hole, and the deviation should be controlled within a certain range, usually not exceeding 3% of the drilling depth. This can be achieved by using high-precision drilling equipment and guide devices.

[0034] Step 2: Anchor rod production and installation. Anchor rods can be made of steel, and their length is determined by the depth of the borehole. The magnetite discarded in the mining area is ground into particles, and the magnetite particles are mixed with cement slurry and other bonding materials to make a magnetic grouting material. The anchor rod is inserted into the borehole, and then the mixed magnetic grouting material is injected into the borehole through the grouting pipe.

[0035] Preferably, the magnetite particles have a particle size range of 2-10 mm, are magnetic, and account for 10%-30% of the volume of the mixed slurry; the bonding material includes cement and sand, wherein the volume ratio of cement to sand is 1:1-1:3, and the bonding material is mixed with the magnetite particles to form a magnetic mixed slurry with viscosity and plasticity, which can provide sufficient compressive strength and bonding force after solidification, and due to the magnetism of the magnetite particles, it generates additional adsorption force with the surrounding rocks and anchors.

[0036] During the specific operation, the slurry is prepared in a magnetic mixed slurry pool. Trace amounts of additives such as waterproofing agents, retarders, etc. may also be added to the magnetic mixed slurry to improve the performance of the magnetic mixed slurry and adapt it to different slope geological conditions and construction environments.

[0037] Preferably, the grouting pipe should be inserted into the bottom of the borehole and placed in the borehole along one side of the anchor rod. When placing the grouting pipe, care should be taken to avoid interference with the installation and fixing of the anchor rod.

[0038] Step 3: Anchor bolt fixing and tensioning. After the grouting material solidifies, the anchor bolt is tightened. A special anchor bolt tensiometer can be used to apply tension. The tightened anchor bolt end is fixed by a pad and nut.

[0039] Specifically, the magnitude of the applied tension is determined according to the design bearing capacity of the anchor rod, and the tension is generally required to reach 70%-90% of the design tension of the anchor rod; the area of ​​the selected pad should be large enough to disperse the tension of the anchor rod and prevent local rock from being crushed; the size of the pad can be calculated based on the tension of the anchor rod and the compressive strength of the rock, and the diameter is generally between 100-300mm.

[0040] like Figure 2 As shown, due to the presence of magnetite, magnetic grouting materials can be better adsorbed on the surrounding rock walls in the borehole than ordinary slurry, and can provide additional friction after solidification, and can also squeeze (discharge) groundwater and gas to the maximum extent during construction.

[0041] Embodiment 2: See also Figure 4 , a comprehensive support method using magnetite in a mining area, comprising the following steps: Retaining wall reinforcement and magnetite utilization include the following steps: Step 1: Retaining wall foundation treatment. Dig the retaining wall foundation pit, the depth and width are determined according to the height of the retaining wall and geological conditions.

[0042] Preferably, there is a crushed stone cushion layer mixed with magnetite at the bottom of the foundation pit. The magnetite can improve the stability and anti-sliding ability of the cushion layer. Such a cushion layer can utilize the magnetic and weight properties of magnetite to better combine the foundation with the foundation soil, while resisting horizontal sliding to a certain extent.

[0043] Step 2: The retaining wall can be made of concrete structure, and a certain proportion of magnetite particles can be added to the concrete; the particle size of the magnetite particles is relatively small, generally between 0.075-0.5mm, and the amount added can account for 5%-15% of the total volume of the concrete.

[0044] Specifically, when the concrete is poured to form a wall, the density of the wall is improved due to the magnetite particles contained in it, and the magnetism also helps to absorb the surrounding iron-containing magnetic particles to enhance the integrity of the wall. A certain number of drainage holes can also be set in the wall, and the spacing of the drainage holes is generally 1-3 meters to drain the accumulated water in the soil behind the wall and reduce the damage to the wall caused by water pressure.

[0045] Embodiment 3: See also Figure 5 Different from the first and second embodiments, in the mine, the prestressed anchor cable and the magnetic mixed mortar containing the expansion agent are used, which includes the following steps: Step 1: Preliminary preparation. Prepare prestressed anchor cable materials, select high-strength, low-relaxation steel strands, and determine according to the designed anchoring force.

[0046] At the same time, prepare matching anchors, pads and other accessories. The anchors must meet the corresponding anchoring performance standards. The thickness of the pads is generally not less than 10mm, and the area is determined based on the anchor tension and the compressive strength of the surrounding rock to effectively disperse the anchor tension.

[0047] For the preparation of magnetic mixed mortar, the particle size of magnetite is 2-10mm; for cement, ordinary Portland cement is used; for sand, medium-coarse sand is selected with a mud content not exceeding 3%, and large particles of impurities and fine powder are removed through screening; the expansive agent is selected according to the characteristics of the mine surrounding rock and engineering requirements, such as calcium sulfoaluminate expansive agent, and its dosage is generally 8%-15% of the cement mass; for admixtures, prepare appropriate amounts of water reducer and early strength agent.

[0048] Step 2: Drilling and installation of anchor cables. Based on the pre-planned layout, use a total station to accurately determine the location of each prestressed anchor cable hole on the mine wall; use drilling equipment to drill holes at the designed angle and depth; cut the steel strands according to the designed length to ensure that the length error is within ±5 cm.

[0049] Specifically, threads are processed at one end of the steel strand, and the thread length meets the requirements for anchor installation, which is generally 10-15 cm. The steel strand is derusted by sandblasting or brushing with rust remover to ensure that there is no rust, oil or other impurities on the surface to improve the bonding strength with the magnetic mixed mortar. The prepared anchor cable is transported to the drilling site to check whether the integrity and size of the anchor cable meet the requirements. Positioning brackets are installed on the anchor cable to ensure that the anchor cable is centered in the borehole. The spacing between the positioning brackets is generally 1-2 meters. Slowly insert the anchor cable into the borehole. The insertion depth meets the design requirements. The exposed length is generally 0.5-1 meter for subsequent tensioning operations.

[0050] Step 3: Preparation and pouring of magnetic mixed mortar. Add cement, sand, magnetite particles, expansion agent, water reducing agent and early strength agent into the mixer in sequence according to the designed ratio. Determine the optimal water-cement ratio through experiments so that the mortar can meet the pouring requirements and ensure strength development.

[0051] Specifically, the stirred magnetic mixed mortar is injected into the anchor cable borehole through the grouting pipe, which is inserted into the bottom of the borehole and grouting is performed from bottom to top. During the grouting process, the grouting pressure is controlled between 2-5 MPa, and the grouting speed is adjusted according to the grouting situation at the orifice. When a large amount of uniform grouting appears at the orifice and the grouting pressure is stable, the grouting is suspended, and the grouting is repeated after a few seconds until there is no grouting at the orifice and the grouting pressure is stable above the design value, indicating that the borehole is full of magnetic mixed mortar.

[0052] Preferably, due to the effect of the expansion agent, the mortar will gradually expand after pouring, further filling the pores and generating radial pressure on the anchor cable, thereby improving the anchoring effect of the anchor cable. At the same time, the magnetism of the magnetite is utilized to make the mortar better adsorbed on the surface of the surrounding rock and the anchor cable, thereby enhancing the overall bonding strength. For example, in the surrounding rock with developed fissures, the expanded magnetic mixed mortar can effectively fill the fissures and cement the loose rock blocks together. At the same time, with the help of the magnetic effect, the mortar, the anchor cable and the surrounding rock form an organic whole, thereby improving the stability and bearing capacity of the support structure.

[0053] Step 4: Anchor cable tensioning and locking. After the magnetic mixed mortar is poured, wait for enough time for the mortar to solidify according to the solidification characteristics of the mortar. Generally, ordinary silicate cement-based magnetic mixed mortar needs to wait for 3-7 days at room temperature (about 20°C) to reach more than 70% of the design strength.

[0054] Specifically, use the anchor cable tensioning equipment to tension the solidified anchor cable. According to the design bearing capacity of the anchor cable, calculate the tension value that needs to be applied, which is generally 70%-90% of the design bearing capacity. Connect the tensioning jack to the exposed threaded end of the anchor cable, slowly apply tension, and observe the reaction of the anchor cable and the surrounding rocks to ensure that the anchor cable is not loose or slipping. After reaching the specified tension, keep the tension stable for a few seconds, and then install the clip of the anchor to lock the anchor cable.

Claims

1. A comprehensive support method using magnetite in mining areas, characterized in that: The following steps are involved: When using bolting in conjunction with magnetite applications: Step 1.1, anchor drilling: Drill holes on the slope at designed spacing and depth; Step 1.2, anchor rod production and installation: The anchor rod is made of steel, and its length is determined according to the depth of the borehole. The magnetite abandoned in the mining area is ground into particles, and the magnetite particles are mixed with a bonding material to make a magnetic mixed slurry with magnetic properties. The anchor rod is inserted into the borehole, and then the mixed magnetic mixed slurry is injected into the borehole through a grouting pipe. Step 1.3, anchor bolt fixing and tightening: After the magnetic mixed slurry solidifies, a special anchor tensile gauge is used to apply tension to tighten the anchor. The tightened anchor ends are fixed with pads and nuts.

2. A comprehensive support method using magnetite in a mining area according to claim 1, characterized in that: The drilling diameter is between 30mm and 100mm; During the drilling process, the verticality of the borehole must be maintained and the deviation should be controlled within a certain range, usually not exceeding 3% of the drilling depth.

3. A comprehensive support method using magnetite in a mining area according to claim 1, characterized in that: The length of the anchor rod is 0.2m-0.5m longer than the depth of the drilling hole, and has a certain tensile strength and surface roughness to facilitate the attachment to the magnetic mixed slurry.

4. A comprehensive support method using magnetite in a mining area according to claim 1, characterized in that: The magnetite particles have a particle size range of 2 mm to 10 mm, are magnetic, and account for 10% to 30% of the volume of the magnetic mixed slurry; The bonding material includes cement and sand, wherein the volume ratio of cement to sand is 1:1-1:

3. The bonding material is mixed with magnetite particles to form a magnetic mixed slurry with viscosity and plasticity. The magnetic mixed slurry can provide sufficient compressive strength and bonding force after solidification, and due to the magnetism of the magnetite particles, it generates additional adsorption force with the surrounding rocks and anchor rods.

5. A comprehensive support method using magnetite in a mining area according to claim 1, characterized in that: The magnetite particles are evenly distributed in the magnetic mixed slurry, and when the slope rock and soil body undergoes slight deformation, the magnetic mixed slurry maintains a relatively stable connection with the rock wall and the anchor by means of the magnetism of the magnetite, thereby reducing the risk of anchor failure; A trace amount of waterproofing agent and retarder are also added to the magnetic mixed slurry as additives to improve the performance of the magnetic mixed slurry and adapt to different slope geological conditions and construction environments.

6. A comprehensive support method using magnetite in a mining area according to claim 1, characterized in that: In step 1.2, the grouting pipe is placed in the borehole along one side of the anchor rod. During the grouting process, the anchor rod is wrapped by the flow of the magnetic mixed slurry, so that the magnetic mixed slurry is in full contact with the anchor rod. Due to the presence of magnetite particles in the magnetic mixed slurry, when the magnetic mixed slurry wraps the anchor rod, the magnetic property of the magnetite will enhance the bonding force with the anchor rod.

7. A comprehensive support method using magnetite in a mining area according to claim 1, characterized in that: The tension applied in step 1.3 is determined according to the design bearing capacity of the anchor rod, and the tension is required to reach 70%-90% of the design tension of the anchor rod; The area of ​​the pad should be large enough to disperse the tension of the anchor rod and prevent local rocks from being crushed; the size of the pad is calculated based on the tension of the anchor rod and the compressive strength of the rock, and the diameter is between 100mm-300mm.

8. A comprehensive support method using magnetite in mining areas, characterized in that: The following steps are involved: Retaining wall reinforcement and magnetite utilization: Step 2.1, retaining wall foundation treatment: Dig the foundation pit of the retaining wall, and lay the foundation with a magnetite crushed stone cushion layer with a particle size of 10mm-30mm. The depth and width are determined according to the height of the retaining wall and geological conditions; Step 2.2, the retaining wall adopts a concrete structure, and a certain proportion of magnetite particles are added to the concrete; the particle size of the magnetite particles is selected between 0.075mm-0.5mm, and the addition amount accounts for 5%-15% of the total volume of the concrete, and drainage holes are set at intervals of 1m-3m.

9. A comprehensive support method using magnetite in a mining area according to claim 8, characterized in that: In the retaining wall reinforcement and magnetite utilization steps, the density of the concrete wall containing magnetite particles is increased by 5%-10% compared with that of the ordinary concrete wall.

10. A comprehensive support method using magnetite in mining areas, characterized in that: The following steps are involved: When supporting prestressed anchor cables and magnetic mixed mortar containing expansion agent in mine tunnels: Step 3.1, preliminary preparation: Prepare prestressed anchor cable materials, select high-strength, low-relaxation steel strands, and determine according to the designed anchoring force. At the same time, prepare matching anchors and pad accessories. The anchors must meet the corresponding anchoring performance standards. The pad thickness is not less than 10mm, and the area is determined based on the anchor cable tension and the surrounding rock compressive strength to effectively disperse the anchor cable tension; prepare magnetic mixed mortar, and the particle size of magnetite is 2mm-10mm; Cement: ordinary Portland cement is used; sand: medium-coarse sand with a mud content of no more than 3%, which is screened to remove large particles of impurities and fine powder; the expansion agent is selected according to the characteristics of the surrounding rock of the mine and the engineering requirements, and its dosage is 8%-15% of the cement mass; admixtures: prepare appropriate amounts of water reducer and early strength agent; Step 3.2, anchor cable drilling and installation: According to the pre-planned layout, use the total station to accurately determine the location of each prestressed anchor cable drill hole on the mine wall; use drilling equipment to drill holes according to the designed angle and depth; cut the steel strands according to the designed length to ensure that the length error is within ±5cm; install positioning brackets on the anchor cable to ensure that the anchor cable is centered in the drill hole. The spacing between the positioning brackets is 1m-2m. Slowly insert the anchor cable into the drill hole. The insertion depth meets the design requirements. The exposed length is 0.5m-1m for subsequent tensioning operations; Step 3.3, preparation and pouring of magnetic mixed mortar: According to the designed proportion, cement, sand, magnetite particles, expansion agent, water reducing agent and early strength agent are added to the mixer in sequence, and a water-cement ratio of 0.4-0.6 is adopted, so that the magnetic mixed mortar can meet the grouting requirements and ensure the strength development; the mixed magnetic mixed mortar is injected into the anchor cable borehole through the grouting pipe, and the grouting pipe is inserted into the bottom of the borehole, and the grouting is performed from bottom to top; when a large amount of uniform grouting appears at the hole mouth and the grouting pressure is stable, the grouting is suspended, and the grouting is repeated after waiting for a few seconds until the hole mouth no longer returns grouting and the grouting pressure is stable above the designed value, indicating that the borehole is full of magnetic mixed mortar; Step 3.4, anchor cable tensioning and locking: After the magnetic mixed mortar is poured, wait for enough time for the magnetic mixed mortar to solidify according to the solidification characteristics of the mortar; use the anchor tensioning equipment to tension the solidified anchor cable, and after reaching the specified tension, keep the tension stable for a few seconds, and then install the anchor clip to lock the anchor cable.

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