A method for mining two-layer ore bodies containing weak interlayers

Abstract

This invention discloses a method for the separate mining of a double-layered ore body containing weak interlayers. The method comprises: S1, division of mining units; S2, layout of mining and cutting operations; S3, a first-step upward segmented drilling and blasting mining of the upper ore layer; and S4, a second-step upward layered mechanical mining of the lower ore layer. The upper ore body is mined one segment height ahead of the lower ore layer, employing segmented deep-hole blasting mining, trackless transportation, and subsequent cemented backfilling. After ore discharge, the lower ore layer undergoes upward horizontal layered mechanized mining and subsequent backfilling, with continuous ore extraction and coordinated support using a roadheader. This method requires only one mining preparation system and achieves separate mining and transportation of a double-layered ore body containing weak interlayers through two orderly mining steps. This significantly reduces the amount of mining preparation work, ensures safe and efficient stope operations, maximizes ore block production capacity, minimizes ore loss and dilution, and has good adaptability to medium-thick or thicker ore bodies with gentle dips, showing broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of mining technology, and in particular to a method for mining a double-layered ore body containing weak interlayers. Background Technology

[0002] As a vital natural resource, minerals are a crucial material foundation for the development of human society. It is universally acknowledged that over 95% of energy, over 80% of industrial raw materials, and over 70% of agricultural production materials originate from mineral resources. Therefore, minerals largely determine the level of social productivity and social change. However, in recent decades, large-scale, high-intensity, and extensive overexploitation has led to the depletion of easily mined, shallow, rich mineral resources. Underground mining is gradually moving towards deeper ore bodies, lower-grade ore bodies, and complex and difficult-to-mine bodies, undoubtedly placing higher demands on mining technology.

[0003] Due to geological formation, ore bodies exhibit complex and varied occurrences. Based on dip angle, they can be classified as horizontal, gently dipping, dipping, and steeply dipping ore bodies. Ore body thickness varies, ranging from thin to medium-thick, thick to extremely thick, with significant coefficients of variation in both thickness and dip angle. Therefore, selecting appropriate mining methods is crucial for ensuring ore productivity and minimizing losses and dilution. Given the diverse occurrences of ore bodies, matching mining methods must be employed for ore bodies with different occurrences, mineral types, and grades. Therefore, a mine typically selects 2-3 mining methods. The mining of widely distributed, closely spaced ore body groups, especially double-layered ore bodies, has always been a challenge for mines. During tectonic movements, weak layers are often interspersed between closely spaced double-layered ore bodies. These layers typically consist of argillaceous or shale-like rocks with low strength and extremely poor stability. Furthermore, the ore grades, thicknesses, and stability of the upper and lower ore bodies differ due to different mineralization periods, making joint mining difficult. To better meet the needs of mineral processing, double-layered ore bodies containing weak interlayers usually require separate mining and transportation. Currently, there are relatively few methods for mining two-layer ore bodies with weak interlayers. In order to meet the needs of safe and efficient mining of such complex ore bodies, it is urgent to invent a method for mining two-layer ore bodies with weak interlayers. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for the separate mining of a double-layered ore body containing weak interlayers.

[0005] The solution of the present invention is:

[0006] A method for mining a double-layered ore body containing weak interlayers includes the following steps:

[0007] S1, Division of mining units

[0008] The ore body is divided into several blocks along the strike. Within each block, the upper and lower ore bodies are simultaneously divided into stops and pillars along the strike. The stopes are 40–80 m long, and the pillars are 4–10 m long. The width of both stops and pillars is the thickness of the double-layer ore body. The height of the stops and pillars is the stage height, which is 40–90 m. Each stage is vertically divided into 3–8 sub-segments, with a sub-segment height of 10–30 m. A 2–5 m thick isolation pillar is set between each sub-segment of the upper ore layer. A 0.5–1.0 m thick bottom pillar is left in the upper ore layer near the interlayer throughout the entire stage. The sub-segments serve as the mining units of the upper ore layer. Each sub-segment of the lower ore layer is vertically divided into 3–5 layers. Each layer has several rectangular access routes with a width of 4–8 m arranged along the strike, which serve as the mining units of the lower ore layer.

[0009] S2, Mining and Cutting Engineering Layout

[0010] Along the strike of the footwall of the ore body, stage transport roadways, external segment transport roadways, and stage return air roadways are set up. Each external segment transport roadway is connected to the two stage roadways by ramps and chutes. Each segment is arranged along the dip of the ore body with a horizontal cross-cutting vein that crosses the external segment transport roadways and stage transport roadways to reach the upper ore layer. The cross-cutting vein is arranged along the strike of the vein and connects to the chutes and ramps at the other end. This forms a system for ore extraction, material transportation, personnel and ventilation, and backfilling in the two ore layers. At the same time, the cross-cutting vein forms a cutting space and free face for access mining in the ore body. As the upward layered mining progresses, the bottom is continuously laid and the top is lifted to keep the production system unobstructed.

[0011] S3. One-step upward segmented drilling and blasting mining of the upper ore layer

[0012] The upper ore layer adopts an upward segmented mining method. In the segmented haulage roadways within the vein, fan-shaped medium-deep holes and boundary control boreholes are arranged radially towards the surrounding rock at a certain spacing. After the stope is charged and blasted, a loader is used to transport the ore through the segmented haulage roadways within the vein and through the cross-vein to the pass, and then unload it into the tandem mine cars in the stage haulage roadway before transferring it to the bottom yard and hoisting it to the surface. Ventilation in the stope is achieved by extending the ventilation duct and pumping the ore through the segmented haulage roadways within the vein, through the cross-vein, and the inclined ramp to the stage return air roadway. After the ore body of this segment is mined, the next segment is immediately moved to prepare for replacement work such as rock drilling. Multiple filling boreholes are drilled in the floor of the segmented haulage roadway within the vein of the previous segment towards this segment, and the filling system is used to subsequently fill the segmented stope.

[0013] S4. Two-step upward stratified mechanical mining of the lower ore layer.

[0014] After the backfill in the upper ore layer sub-mining has solidified and the ore in the upper ore layer has been unloaded in the pass, the mining of the lower ore layer is carried out in the following mining sequence: advancing type within the access road, intermittent type within the access road, and upward type within the access road. Within the access road, a roadheader is used to mechanically cut the ore body for continuous ore dropping. The ore is unloaded from the tail of the roadheader onto the bottom plate and then shoveled and transported to the pass by a loader. From the pass, it is released to the tandem ore cars in the stage transport roadway and then transported to the bottom yard and hoisted to the surface. The roadheader can simultaneously carry out anchor mesh support work on the surrounding rock of the access road. The ventilation of the mining area is extracted to the stage return air roadway through the ventilation ducts arranged in the access road, cross-section and inclined roadway. After the access road is mined, a backfill retaining wall is constructed and backfilled with the help of the backfilling system. The bottom layer is constructed by pouring reinforced concrete to build an artificial false bottom after mining. After the ore in the lower ore layer in the pass is unloaded, the replacement sub-mining with drilled holes in the upper ore layer is blasted, and the operation is carried out in cycles according to the S3 steps.

[0015] As a preferred technical solution, the ore body is a medium-thick ore body that dips gently to steeply, with a dip angle >5° and a thickness >4m.

[0016] As a preferred technical solution, the cross-sectional shape of the stage roadway, the segmented transport roadway inside and outside the vein, the through roadway, and the inclined roadway is one of the following: a three-centered arch, a straight-wall arch, a rectangle, or a trapezoid, with a cross-sectional area ≥ 12m². 2 The diameter of the chute cross section is ≥1.0m.

[0017] As a preferred technical solution, the fan-shaped medium-deep holes in the upper ore layer segmented stope have a diameter of 50-75mm, a depth of 5-20m, a row spacing of 1-3m, and a bottom-to-bottom distance of 1-3m. They are detonated using non-electric detonating cords with micro-delay initiation. The boundary control borehole parameters are consistent with the blasting medium-deep hole parameters, and they are not loaded with explosives. They are arranged parallel to the dip direction of the ore body to control the blasting boundary of the stope and prevent blasting from damaging the stability of the bottom pillar.

[0018] As a preferred technical solution, the upper and lower ore layers are mined in two steps. After the first step of mining the upper ore layer, including the filling of the segmented stope and ore transportation, is completed, the second step of mining the lower ore layer can begin. After all the layered mining and filling processes within the lower ore layer segment are completed and ore transportation is finished, the next segment of the upper ore layer is then mined by blasting (drilling operations can be carried out simultaneously in the segmented stope of the upper ore layer during the mining of the lower ore layer, but blasting and ore transportation are not allowed). The upper ore layer should be mined one segment ahead of the lower ore layer in terms of mining height to ensure that the cross-section is not damaged by the mining of the lower ore body during the mining of the upper ore layer.

[0019] As a preferred technical solution, when the ore body of the lower ore layer is relatively hard and difficult to cut mechanically, a horizontal medium-deep hole with a diameter of 60-90mm and a depth of 10-30m is drilled in the center of the access route, and hydraulic fracturing or loosening blasting is used for segmented pre-fracture; the rock mass cutability is improved by increasing the degree of joint and fracture development of the ore body in the access route, and mechanical cutting is carried out after pre-fracture.

[0020] As a preferred technical solution, mining and backfilling operations are carried out simultaneously in 2 to 3 access routes within the lower ore layer, with the backfilling and access route mining processes being carried out in parallel.

[0021] As a preferred technical solution, the anchor mesh support is either anchor bolt mesh support or anchor cable mesh support; the anchor bolt is a resin anchor bolt with a diameter of 18-25mm and a length of 2.0-3.0m; the anchor cable is a steel strand with a diameter of 15-25mm and a length of 3.0-7.5m; the anchor bolts are spaced 1-2m apart with a spacing of 0.6-1.5m; the anchor cables are spaced 1-2m apart with a spacing of 0.6-1.5m.

[0022] As a preferred technical solution, the filling retaining wall and the concrete false bottom are poured with C20 grade or higher concrete, and the ash-sand mass ratio of the tailings cemented filling slurry is ≥1:8 and the mass concentration is ≥68%.

[0023] The above-mentioned technical solution is used to develop a method for mining a double-layer ore body containing a weak interlayer, which includes the following steps: S1. Dividing the mining unit: The ore body is divided into several blocks along the strike. The upper and lower layers of the ore body within each block are simultaneously divided into stops and pillars along the strike. The length of the stops is 40-80m, and the length of the pillars is 4-10m. The width of the stops and pillars is the thickness of the double-layer ore body. The height of the stops and pillars is the stage height, which is 40-90m. Each stage is divided vertically into 3-8 segments with a segment height of 10-30m. A 2-5m thick isolation pillar is set between each segment of the upper ore layer. A 0.5-1m thick isolation pillar is left in the upper ore layer near the interlayer throughout the entire stage.A 0m thick base pillar is used as a mining unit for the upper ore layer. The lower ore layer is vertically divided into 3-5 layers, each containing several rectangular access roads 4-8m wide and arranged along the strike, serving as mining units for the lower ore layer. For the S2 mining and cutting layout, stage haulage roadways, external haulage roadways, and stage return air roadways are set up along the strike in the footwall of the ore body. Each external haulage roadway is connected to the two stage roadways via ramps and chutes. Each section has a haulage roadway along the dip of the ore body, one end of which crosses the external haulage roadways and stage haulage roadways to reach the internal haulage roadway arranged along the strike in the upper ore layer; the other end connects to the chutes and ramps. The horizontal cross-cutting veins form the systems for ore extraction, material transportation, personnel and ventilation, and backfilling in the two ore layers. Simultaneously, the cross-cutting veins create cutting spaces and free faces within the ore body, and the bottom and top are continuously laid and lifted during upward layered mining to maintain the smooth operation of the production system. S3: One-step upward segmented drilling and blasting mining of the upper ore layer. The upper ore layer adopts upward segmented mining. In the segmented haulage roadways within the veins, fan-shaped medium-deep holes and boundary control boreholes are arranged radially towards the surrounding rock at a certain spacing. After blasting in the stope, a loader transports the ore through the segmented haulage roadways within the veins and the cross-cutting veins to the pass, unloads it into the tandem mine cars in the stage haulage roadways, and then transfers it to the bottom yard for hoisting to the surface. Ventilation in the stope is achieved by extending ventilation ducts and pumping air through segmented transport roadways, cross-cutting roads, and inclined ramps to the stage return airway. After the ore body in this segment is mined, the work immediately moves to the next segment for drilling and other preparatory work. Multiple filling boreholes are drilled in the floor of the segmented transport roadway in the previous segment, and a filling system is used to fill the segmented stope subsequently. S4: The lower ore layer is mechanically mined using a two-step upward layered approach. After the filling body in the upper ore layer segmented stope has solidified and the upper ore layer ore has been unloaded from the ore pass, the lower ore layer is mined according to the following mining sequence: forward mining within the approach, intermittent mining within the layer, and upward layered mining within the block. The approach uses a tunneling and anchoring method. The machine continuously cuts and cuts the ore body, unloading it from the tail of the roadheader onto the floor plate, where it is then shoveled and transported to the pass. From the pass, it is released into tandem ore cars in the stage transport roadway and then transported to the bottom yard for hoisting to the surface. Simultaneously, the roadheader can perform anchor mesh support work on the surrounding rock of the access roadway. Ventilation in the stope is extracted through ventilation ducts arranged in the access roadway, crosscuts, and ramps to the stage return airway. After the access roadway is mined, a backfill retaining wall is constructed, and subsequent backfilling is carried out using a backfilling system. The lowest level is constructed by pouring reinforced concrete to create an artificial false floor. After the ore from the lower ore layer in the pass is unloaded, blasting is carried out in the adjacent sub-stope with pre-drilled holes in the upper ore layer, following the S3 procedure in a cyclical operation.

[0024] Advantages of this invention:

[0025] (1) The upper and lower ore layers share a single external mining preparation system to realize the separate mining and transportation of ore, which greatly reduces the amount of engineering work in the mining preparation roadway and lowers the cost of mine construction;

[0026] (2) The one-step upward segmented deep hole drilling and blasting mining of the upper ore layer and the two-step upward layered mechanical mining of the lower ore layer significantly improved the production capacity and safety and efficiency of the stope. Moreover, the two are coordinated and orderly, with little ore loss and dilution, and have strong adaptability to various types of ore bodies.

[0027] (3) The bottom support pillars and boundary control boreholes left in the upper ore layer effectively reduce the amount of over- and under-excavation work in the upper ore layer mining area and the destructive impact of blasting disturbance on the stability of the interlayer. Attached Figure Description

[0028] Figure 1 This is a side view of the mining method in Embodiment 1 of the present invention;

[0029] Figure 2 This is a front view of mining method AA according to Embodiment 1 of the present invention;

[0030] Figure 3 This is a front view of the mining method BB in Embodiment 1 of the present invention;

[0031] Figure 4 This is a top view of the mining method (CC) according to Embodiment 1 of the present invention;

[0032] Figure 5 This is a top view of the mining method DD according to Embodiment 1 of the present invention;

[0033] Figure 6 This is a top view of the mining method EE in Embodiment 1 of the present invention.

[0034] Among them: 1-stope; 2-pillar; 3-sloping ramp; 4-pass chute; 5-stage haulage roadway; 6-stage return airway; 7-external segmented haulage roadway; 8-through vein; 9-concrete false bottom; 10-access roadway; 11-heading and anchoring machine; 12-anchor mesh; 13-filling body; 14-interlayer; 15-bottom support pillar; 16-isolation layer pillar; 17-inter-vein segmented haulage roadway; 18-medium-deep hole; 19-boundary control hole; 20-filling hole; 21-filling retaining wall. Detailed Implementation

[0035] This invention provides a method for mining two-layer ore bodies containing weak interlayers.

[0036] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0037] Example 1:

[0038] like Figures 1-6As shown, firstly, the ore body is divided into several blocks along the strike. Within each block, the upper and lower ore bodies are simultaneously divided along the strike into stopes 1 and pillars 2. Stopes 1 are 40–80 m long, and pillars 2 are 4–10 m long. The width of both stops 1 and pillars 2 is the thickness of the double-layer ore body, and the height is the stage height (40–90 m). Each stage is vertically divided into 3–8 segments, with a segment height of 10–30 m. A 2–5 m thick isolation pillar 16 is set between each segment of the upper ore layer. In the upper ore layer, a 0.5–1.0 m thick bottom support pillar 15 is left throughout the entire stage near the interlayer 14. The segments serve as the mining units of the upper ore layer. The lower ore layer is vertically divided into 3–5 layers within each segment. Each layer is further subdivided into several rectangular access roads 10 with a width of 4–8 m arranged along the strike, which serve as the mining units of the lower ore layer.

[0039] Secondly, stage haulage roadways 5, external segmented haulage roadways 7, and stage return air roadways 6 are constructed along the strike of the footwall of the ore body. Each external segmented haulage roadway 7 and the two stage roadways 5 and 6 are connected by ramps 3 and chutes 4. Each segment has a horizontal cross-cutting vein 8 arranged along the dip of the ore body, one end of which crosses the external segmented haulage roadways 7 and stage haulage roadways 5 to reach the upper ore layer, while the other end connects to the chutes 4 and ramps 3. This forms a system for ore extraction, material transportation, pedestrian access, ventilation, and backfilling between the two ore layers. Simultaneously, the cross-cutting vein 8 creates cutting space and free faces for the mining of access road 10 within the ore body, and continuously lays the bottom and lifts the top as the upward layered mining progresses to maintain the smooth operation of the production system. The diameter of the chutes 4 is not less than 1.0m. The cross-sections of other preparatory roadways are one of three-centered arch, straight-wall arch, rectangular, or trapezoidal shapes, with an area of ​​not less than 12m². 2 .

[0040] Secondly, the upper ore layer is first mined using an upward segmented mining method. In the segmented haulage roadway 17 within the vein, fan-shaped medium-deep boreholes 18 and boundary control boreholes 19 are arranged radially towards the surrounding rock at a certain spacing. After the stope is charged and blasted, a loader is used to transport the ore through the segmented haulage roadway 17 and the cross-vein 8 to the pass 4, and then unload it into the tandem mine cars in the stage haulage roadway 5 before transferring it to the bottom yard and hoisting it to the surface. Ventilation in the stope is achieved by extending the ventilation duct and pumping the ore through the segmented haulage roadway 17, the cross-vein 8, and the inclined ramp 3 to the stage return air roadway 6. After the ore body of this segment is mined, the work immediately moves to the next segment for replacement preparation work such as drilling. Multiple filling boreholes 20 are drilled in the floor of the segmented haulage roadway 17 of the previous segment towards this segment, and the filling system is used to subsequently fill the segmented stope.

[0041] Finally, after the filling body 13 in the upper ore layer sub-mining has solidified and the upper ore layer in the ore pass 4 has been unloaded, the mining of the lower ore layer will proceed in the following mining sequence: advancing type in the access road 10, intermittent type in the access road within the layer, and upward type in the access road within the ore block. In access road 10, a roadheader 11 is used to mechanically cut the ore body and continuously cut the ore. The ore is unloaded from the tail of the roadheader onto the bottom plate and then shoveled and transported to the pass 4 by a loader. From the pass 4, the ore is released into the stage transport roadway 5 and then transported to the bottom yard and lifted to the surface. The roadheader 11 can simultaneously carry out anchor mesh 12 support operations on the surrounding rock of the access road. The ventilation of the stope is extracted to the stage return air roadway 6 through the ventilation ducts arranged in access road 10, cross vein 8 and inclined ramp 3. After the access road 10 is mined, a backfill retaining wall 21 is constructed and backfilled with the help of a backfilling system. The bottom layer is constructed by pouring reinforced concrete to build an artificial false bottom 9 after mining. After the ore in the lower ore layer in the pass is unloaded, the replacement sub-stope with the boreholes drilled in the upper ore layer is blasted and the operation is carried out in a cycle according to step S3.

[0042] The fan-shaped medium-deep boreholes 18 in the upper ore layer sub-mining have an inclination angle of 15-90°, a diameter of 50-75mm, a depth of 5-20m, a row spacing of 1-3m, and a bottom-to-bottom distance of 1-3m. They are detonated using non-electric detonating cords with micro-delay initiation. The parameters of the boundary control boreholes 19 are the same as those of the blasting medium-deep boreholes. They are not loaded with explosives and are arranged parallel to the dip direction of the ore body to control the blasting boundary of the mining area to prevent blasting from damaging the stability of the bottom support pillars 15.

[0043] The upper and lower ore layers are mined in two steps. The lower ore layer can only be mined in the second step after the backfilling and ore transportation of the upper ore layer's segmented stope are completed. The next segment of the upper ore layer will be blasted for mining only after all layered mining and backfilling processes within the lower ore layer's segment are completed and ore transportation is finished. (Drilling operations in the upper ore layer's segmented stope can be carried out simultaneously during the mining of the lower ore layer, but blasting and ore transportation are prohibited). The upper ore layer should be mined one segment ahead of the lower ore layer in terms of mining height to ensure that the cross-section 8 is not damaged by the mining of the lower ore body during the mining of the upper ore layer.

[0044] When the ore body of the lower ore layer, access route 10, is too hard to be mechanically cut, a horizontal medium-deep hole with a diameter of 60-90 mm and a depth of 10-30 m is drilled in the center of access route 10. Hydraulic fracturing or loosening blasting methods are used for segmented pre-fracture. By increasing the degree of joint and fracture development in the ore body of access route 10, the rock mass's cutability is improved. Mechanical cutting is then performed after pre-fracture.

[0045] Within the lower ore layer, mining and backfilling operations can be carried out simultaneously in 2 to 3 access routes 10, and backfilling and access route mining processes can be carried out in parallel.

[0046] Anchor mesh 12 support is one of anchor rod mesh support or anchor cable mesh support; the anchor rod is a resin anchor rod with a diameter of 18-25mm and a length of 2.0-3.0m, and the anchor cable is a steel strand with a diameter of 15-25mm and a length of 3.0-7.5m; the row spacing is 1-2m and the interval is 0.6-1.5m.

[0047] The filling retaining wall 21 and the concrete false bottom 9 are made of C20 grade or higher concrete. The ash-sand mass ratio of the tailings cemented filling slurry is ≥1:8 and the mass concentration is ≥68%.

[0048] The steps of the present invention are described below with reference to an embodiment:

[0049] A certain phosphate mine has a designed production capacity of 2 million tons / year. The ore body is buried at a depth of 500-1000m, with a strike length of 1000m and a dip angle of 55°. The ore body has a "sandwich" structure, with average thicknesses of 6.5m and 12.0m for the upper and lower ore layers, and average P2O5 grades of 22.48% and 26.90%, respectively. The lithology is phosphate rock containing calcium fluorophosphate; the interlayer is argillaceous shale with a thickness of 0.5-2.0m. To meet the mine's production scale requirements, the implementation steps of this mining method are as follows:

[0050] (S1) Division of mining units: First, the ore body is divided into several blocks along the strike. The upper and lower layers of the ore body within the block are simultaneously divided along the strike into stope 1 and pillar 2. Stope 1 is 50m long and pillar 2 is 5m long. The width of stope 1 and pillar 2 is the thickness of the double-layer ore body, and the height is the stage height (48m). The stage is divided into 4 segments along the vertical direction, with a segment height of 12m. A 2m thick isolation layer pillar 16 is set between each segment of the upper ore layer. A 0.5m thick bottom support pillar 15 is left in the upper ore layer near the interlayer 14 throughout the entire stage. The segment is used as the mining unit of the upper ore layer. The lower ore layer is divided into 3 layers vertically within the segment. Each layer is further subdivided into 3 rectangular access roads 10 with a width of 4m along the strike as the mining unit of the lower ore layer.

[0051] (S2) Mining and Cutting Engineering Layout: A stage haulage roadway 5, an external segmented haulage roadway 7, and a stage return airway 6 are set up along the strike of the footwall of the ore body. Each external segmented haulage roadway 7 and the two stage roadways 5 and 6 are connected by ramps 3 and chutes 4. Each segment has a horizontal cross-cutting vein 8 arranged along the dip of the ore body, with one end passing through the external segmented haulage roadway 7 and the stage haulage roadway 5 to reach the upper ore layer, and the other end connecting to the chutes 4 and ramps 3. This forms a system for ore extraction, material transportation, pedestrian access, ventilation, and backfilling between the two ore layers. Simultaneously, the cross-cutting vein 8 forms the cutting space and free face for the mining of the approach roadway 10 within the ore body, and is continuously paved and the roof is raised as the upward layered mining progresses to maintain the smooth operation of the production system. The chutes 4 have a diameter of 2.0m, and the other preparatory roadways have a net width of 4.5m, a wall height of 2.5m, and an arch height of 1.5m.

[0052] (S3) One-step upward segmented drilling and blasting mining of the upper ore layer: The upper ore layer is first mined using an upward segmented method. In the segmented transport roadway 17 within the vein, fan-shaped medium-deep boreholes 18 and boundary control boreholes 19 (without explosives) are arranged radially towards the surrounding rock at a spacing of 1.5m. The diameter of the medium-deep boreholes is 60mm, and the spacing is 1.5m. After the explosives are charged in the stope, non-electric detonating cords are used for micro-delay detonation. After blasting, a loader is used to transport the ore through the segmented transport roadway 17 and the cross-vein 8 to the pass 4, and then unload it into the tandem mine car in the stage transport roadway 5 before transferring it to the bottom yard and hoisting it to the surface. Ventilation in the stope is achieved by extending the ventilation duct and pumping the ore through the segmented transport roadway 17, the cross-vein 8, and the inclined ramp 3 to the stage return air roadway 6. After the ore body in this section is mined, the work will be transferred to the previous section for replacement work such as drilling. Multiple filling boreholes 20 (30cm in diameter) will be drilled in the bottom plate of the sub-section transport roadway 17 in the vein of the previous section towards this section. The sub-section mining area will then be filled with tailings cemented filling system at a lime-sand ratio of 1:8 and a mass concentration of 68%.

[0053] (S4) Two-step upward layered mechanical mining of the lower ore layer: After the filling body 13 of the upper ore layer sub-stope has solidified and the ore in the upper ore layer in the pass 4 has been unloaded, the lower ore layer is mined in the following mining sequence: forward mining in the access road 10, intermittent mining in the layered access road, and upward mining in the ore block. In the access road 10, the ore body is mechanically cut and continuously ore is dropped from the tail of the access road 11. The ore is unloaded from the tail of the access road 11 onto the bottom plate and then shoveled and transported to the pass 4 by a loader. From the pass 4, the ore is released into the tandem ore car in the stage transport roadway 5 and then transported to the bottom yard and hoisted to the surface. The roadheader 11 can simultaneously perform anchor mesh 12 support operations on the surrounding rock of the access road. The anchor bolts are 20mm in diameter, 2.2m long, and spaced 0.8m x 1.0m apart. The metal mesh is made of No. 6 steel reinforcement and has a mesh opening of 10cm x 10cm. Ventilation in the stope is drawn out to the stage return airway 6 through ventilation ducts arranged in the access road 10, the cross-cutting 8, and the inclined ramp 3. After the access road 10 is mined, a backfill retaining wall 21 (C30 concrete, 30cm thick) is constructed. The backfill system is used for subsequent tailings cemented backfilling (slurry ash-sand ratio 1:8, mass concentration 68%). Two sets of backfilling processes and access road mining are carried out simultaneously in the layer. After the bottom layer of the lower ore block is mined, reinforced concrete (20mm round steel bars, C30 grade concrete) is poured to construct an artificial false bottom 9. After the ore in the lower ore layer is unloaded in the ore pass, the adjacent sub-stope with drilled holes in the upper ore layer is blasted, and the operation is carried out in a cycle according to step S3. This method has a daily production capacity of 1000t / d for ore blocks, with ore loss and dilution both below 5%, effectively ensuring the scale of mine production capacity.

[0054] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for mining a double-layered ore body containing weak interlayers, characterized in that, Includes the following steps: S1, Division of mining units The ore body is divided into several blocks along the strike. Within each block, the upper and lower ore bodies are simultaneously divided into stops and pillars along the strike. The stopes are 40–80 m long, and the pillars are 4–10 m long. The width of both stops and pillars is the thickness of the double-layer ore body. The height of the stops and pillars is the stage height, which is 40–90 m. Each stage is vertically divided into 3–8 sub-segments, with a sub-segment height of 10–30 m. A 2–5 m thick isolation pillar is set between each sub-segment of the upper ore layer. A 0.5–1.0 m thick bottom pillar is left in the upper ore layer near the interlayer throughout the entire stage. The sub-segments serve as the mining units of the upper ore layer. Each sub-segment of the lower ore layer is vertically divided into 3–5 layers. Each layer has several rectangular access routes with a width of 4–8 m arranged along the strike, which serve as the mining units of the lower ore layer. S2, Mining and Cutting Engineering Layout Along the strike of the footwall of the ore body, stage transport roadways, external segment transport roadways, and stage return air roadways are set up. Each external segment transport roadway is connected to the two stage roadways by ramps and chutes. Each segment is arranged along the dip of the ore body with a horizontal cross-cutting vein that crosses the external segment transport roadways and stage transport roadways to reach the upper ore layer. The cross-cutting vein is arranged along the strike of the vein and connects to the chutes and ramps at the other end. This forms the ore extraction, material transportation, personnel and ventilation and filling system for the two ore layers. At the same time, the cross-cutting vein forms the cutting space and free face for the approach mining in the ore body. As the upward layered mining is carried out, the bottom is continuously laid and the top is lifted to keep the production system unobstructed. S3. One-step upward segmented drilling and blasting mining of the upper ore layer The upper ore layer adopts an upward segmented mining method. In the segmented haulage roadways within the vein, fan-shaped medium-deep holes and boundary control boreholes are arranged radially towards the surrounding rock at a certain spacing. After the stope is charged and blasted, a loader is used to transport the ore through the segmented haulage roadways within the vein and through the cross-vein to the pass, and then unload it into the tandem mine cars in the stage haulage roadway before transferring it to the bottom yard and hoisting it to the surface. Ventilation in the stope is achieved by extending the ventilation duct and pumping the ore through the segmented haulage roadways within the vein, through the cross-vein, and the inclined ramp to the stage return air roadway. After the ore body of this segment is mined, the work is immediately moved to the next segment for drilling replacement preparation. Multiple filling boreholes are drilled in the floor of the segmented haulage roadway within the vein of the previous segment towards this segment. The filling system is also used to subsequently fill the segmented stope. S4. Two-step upward stratified mechanical mining of the lower ore layer. After the backfill in the upper ore layer sub-mining has solidified and the ore in the upper ore layer has been unloaded in the pass, the mining of the lower ore layer is carried out in the following mining sequence: advancing type within the access road, intermittent type within the access road, and upward type within the access road. Within the access road, a roadheader is used to mechanically cut the ore body for continuous ore dropping. The ore is unloaded from the tail of the roadheader onto the bottom plate and then shoveled and transported to the pass by a loader. From the pass, it is released to the tandem ore cars in the stage transport roadway and then transported to the bottom yard and hoisted to the surface. The roadheader can simultaneously carry out anchor mesh support work on the surrounding rock of the access road. The ventilation of the mining area is extracted to the stage return air roadway through the ventilation ducts arranged in the access road, cross-section and inclined roadway. After the access road is mined, a backfill retaining wall is constructed and backfilled with the help of the backfilling system. The bottom layer is constructed by pouring reinforced concrete to build an artificial false bottom after mining. After the ore in the lower ore layer in the pass is unloaded, the replacement sub-mining with drilled holes in the upper ore layer is blasted, and the operation is carried out in cycles according to the S3 steps.

2. The method for mining a double-layered ore body containing weak interlayers as described in claim 1, characterized in that: The ore body is a medium-thick ore body that dips gently to steeply, with a dip angle >5° and a thickness >4m.

3. The method for mining a double-layered ore body containing weak interlayers as described in claim 1, characterized in that: The cross-sectional shape of the aforementioned stage roadways, intra- and extra-vein segmented transport roadways, cross-vein roadways, and ramp roadways is one of the following: three-centered arch, straight-wall arch, rectangular, or trapezoidal, with a cross-sectional area ≥ 12m². 2 The diameter of the chute cross section is ≥1.0m.

4. The method for mining a double-layered ore body containing weak interlayers as described in claim 1, characterized in that: The fan-shaped medium-deep holes in the upper ore layer segmented mining area have a diameter of 50-75mm, a depth of 5-20m, a row spacing of 1-3m, and a hole bottom distance of 1-3m.

5. The method for mining a double-layered ore body containing weak interlayers as described in claim 1, characterized in that: When the ore body in the lower ore layer is too hard to be mechanically cut, a horizontal medium-deep hole with a diameter of 60-90 mm and a depth of 10-30 m is drilled in the center of the access road, and segmented pre-fracture is carried out by hydraulic fracturing or loosening blasting.

6. The method for mining a double-layered ore body containing weak interlayers as described in claim 1, characterized in that: Within the lower ore layer, mining and backfilling operations are carried out simultaneously on 2 to 3 routes, with backfilling and route mining processes conducted in parallel.

7. The method for mining a double-layered ore body containing weak interlayers as described in claim 1, characterized in that: The anchor mesh support is one of anchor bolt mesh support or anchor cable mesh support; the anchor bolt is a resin anchor bolt with a diameter of 18-25mm and a length of 2.0-3.0m; the anchor cable is a steel strand with a diameter of 15-25mm and a length of 3.0-7.5m; the anchor bolts are spaced 1-2m apart with a spacing of 0.6-1.5m; the anchor cables are spaced 1-2m apart with a spacing of 0.6-1.5m.

8. The method for mining a double-layered ore body containing weak interlayers as described in claim 1, characterized in that: The filling retaining wall and the concrete false bottom are constructed with C20 grade or higher concrete, and the ash-sand mass ratio of the tailings cemented filling slurry is ≥1:8 with a mass concentration of ≥68%.

Images