A mechanized method of mining pillars in a sublevel open stope subsequent backfilling method

Abstract

This invention relates to the field of underground mining technology for metal deposits, specifically to a mechanized method for recovering pillars using the sublevel stope backfilling method. The method, based on the sublevel stope backfilling mining method, involves recovering the remaining pillars using a strip-path upward layered backfilling method after the stope has been mined and backfilled. Backfilling paths are arranged from the main mining line along the vein at a downward slope of 5%-15% towards the inter-pillars, with one path on each side of adjacent inter-pillars in the stope, ensuring safe recovery. This method, after the stope has been mined and backfilled, recovers the pillars to reduce ore loss and increase the recovery rate of mineral resources.

Description

Technical Field

[0001] This invention relates to the field of underground mining technology for metal deposits, specifically to a mechanized segmented open-cut subsequent backfilling method for pillar mining. Background Technology

[0002] As non-renewable resources, mineral resources are facing increasing scarcity in today's rapidly developing socio-economic environment. To address this shortage, it is crucial to continuously improve the recovery of mineral resources during the mining process. Mineral resource extraction is a source of economic benefits for mines, and in addition to mining new mineral resources, recovering the large number of residual pillars left over from previous mining operations is also a vital step in ensuring mine production.

[0003] Traditional mechanized segmented open-cut backfilling methods divide ore blocks into stops and pillars. Stopes are mined with the support of pillars, and after stope mining, non-cemented backfilling with waste rock and tailings is used. However, due to stope blasting damage and stress concentration within the pillars, they become encased in non-cemented materials such as tailings. The low cohesion and limited self-supporting height of the tailings mean the pillars are not mined and are lost. This mining method was widely used in the early stages of most mines, leaving behind numerous pillars and causing resource losses.

[0004] To address the issue of pillar recovery in mechanized segmented open area subsequent backfilling, it is necessary to adopt a new mining method to improve resource recovery and utilization. Summary of the Invention

[0005] To address the issue of ore pillar resource loss caused by the subsequent filling of mechanized segmented stopes, this invention provides a method for recovering ore pillars left by this mining method. After the stope recovery and filling are completed, the ore pillars are recovered to reduce ore loss and increase the ore recovery rate.

[0006] To achieve the above-mentioned technical objectives, the present invention is implemented through the following technical solution:

[0007] A method for mechanized segmented open-cut subsequent backfilling pillar mining, characterized by the following steps:

[0008] S1: Pillar mining unit division: The arrangement of ore blocks in the segmented open-cut subsequent filling mining method. The pillars are arranged perpendicular to the ore body strike (interstitial pillars) and along the ore body strike (top and bottom pillars). Two adjacent interstitial pillars and the bottom pillar between them are considered as a mining unit. The pillars are mined vertically in a strip-cut approach with upward layering, and a certain width of ore wall is reserved on both sides of the strip-cut approach.

[0009] S2: Mining preparation engineering layout: At the location of the mining preparation trunk line corresponding to each segment pillar, construct the mining connecting road to the pillar at a downward slope of 5%-13%. Then, arrange the mining access road in the pillar with a flat slope. The mining access roads arranged in adjacent pillars and the mining access roads in the top and bottom pillars are interconnected to form a safety exit and ventilation flow. At the same time, arrange the riser (or filling borehole) to the upper hanging wall of the ore body to fill the return air system at an appropriate location in the pillar.

[0010] S3: Mining and Backfilling: Upward layered mining is adopted, with one strip access road arranged in each layer. During the mining process, the roof is supported by anchor bolts, anchor bolts + anchor mesh, etc., according to the stability of the roof. After the mining of a layer is completed, the strip is backfilled to a height of 2.5-3.5m using non-cemented backfilling, and then 0.5m of surface cemented backfilling is carried out. As the mining layers rise, the mining connecting road is gradually raised by shaving the top and using the raised surrounding rock to raise the bottom plate, forming mining connecting roadways that lead to each layer. At this time, the corresponding drilling roadways and ore extraction access roads at the lower part will be backfilled.

[0011] Furthermore, in step S1, the width of the strip access is determined according to the width of the mined pillar, generally 4.3-4.5m, and the height is 4-5m. A 0.5-0.7m wide ore wall is left between the strip access and the stope filling body.

[0012] Furthermore, in step S2, the bottom layer of the strip is filled with tailings and waste rock, followed by a 0.5m thick cemented surface layer with a compressive strength of 1.5-2 MPa; the strip is layered from the filling well (or filling borehole) arranged in the pillar to the strip access layer, and filling is carried out after each layer is mined.

[0013] Furthermore, in step S3, after the first layer of mining is completed, the filling height is 2.5-3.5m, leaving a height of 1.5m as the free face and compensation space for the upper layer blasting.

[0014] Furthermore, in step S1, the pillars are arranged according to the ore blocks, with two adjacent inter-pillars and the bottom pillar between them forming a mining unit.

[0015] Furthermore, a loader is used to remove the ore and transport it to a sectional pass. The ore is then transported to the main shaft hoisting system via a rail-guided system in the intermediate section after reaching the end of the pass. In areas or sections far from the pass, 15-20t trucks can be used in conjunction with loaders to remove the ore.

[0016] Furthermore, the approach-type upward layered filling method is adopted for mining, the mining face is a single-ended roadway, and the combined extraction and pressure ventilation is adopted, with the waste air entering the return air system from the segmented mining preparation trunk line.

[0017] The beneficial effects of this invention are:

[0018] This invention relates to a mechanized segmented stope backfilling method for pillar mining. Based on the segmented stope backfilling mining method, after the stope mining and backfilling are completed, the pillars between the stops are mined using an upward layered backfilling method with access routes. A backfilling access route is arranged from the main mining line down a slope of 5%-15% to the pillars. A backfilling access route is arranged in each of the two adjacent pillars and the top and bottom pillars between them to achieve safe mining. The method of this invention, after the stope mining and backfilling are completed, mines the pillars to reduce ore loss and improve the ore recovery rate.

[0019] Compared to traditional pillar mining methods, the pillar mining method described in this invention, which utilizes a backfilling mining process, employs pillar mining unit division, upward layered mining, and backfilling technology. This approach maximizes resource utilization within the mining area while ensuring mining efficiency. Furthermore, it offers the following advantages:

[0020] Improved resource recovery rate: Traditional mechanized segmented open-cut backfilling method results in permanent loss of ore pillars, which cannot be recovered, leading to a high ore loss rate. In contrast, the mining method for recovering ore pillars in this invention employs an upward strip approach with layered backfilling, allowing for the recovery of a portion of the pillar resources and thus improving the resource recovery rate.

[0021] It creates economic and social benefits: The mining method of the pillar recovery method of the present invention makes full use of the mechanized segmented open area subsequent filling method for the preparation project, which reduces the amount of preparation project. The bottom layer of each layer of filling uses non-gel end sand and waste rock filling, which is low cost and pillar recovery cost. It not only creates economic benefits for the mine, but also extends the service life of the mine.

[0022] Safety of pillar mining: Pillar mining inevitably disrupts the equilibrium stress environment, causing stress transfer to the roof above the pillar and stress concentration at the edges. This concentrated stress further increases the lateral pressure on tailings within the stope. The strip mining method, with its small exposed space, reduces stress changes caused by excavation disturbance. Furthermore, the pre-reserved sidewalls on both sides limit tailings collapse and support the lateral pressure on the tailings, ensuring safety during pillar mining.

[0023] Improving mining grade: The characteristics of the upward stratified strip approach allow for the separation of interbedded rocks from ore at the mining face; at the same time, when the ore body boundary is irregular, the strip approach can adapt well to the irregular shape of the ore body, thereby reducing dilution, improving the mining grade of ore, and increasing economic benefits. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the working conditions of the method described in this invention;

[0026] Figure 2 This is a schematic cross-sectional view of the working condition of the method described in this invention;

[0027] Figure 3 This is a schematic longitudinal section diagram of the working condition of the method described in this invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] like Figure 1 As shown

[0031] The method for mechanized segmented open-cut subsequent backfilling pillar mining as described in this embodiment includes the following steps:

[0032] Pillars, access strips structure and parameters: Pillars are arranged perpendicular to and along the strike of the ore body. The strips are arranged according to the strike of the pillars. The pillars are 5m wide and 20m thick vertically. The first layer of the access strip has a mining height of 5m, and the other layers have a mining height of 4m and a width of 3.6m. Pillars with a width of 0.7m are reserved on both sides of each access strip.

[0033] Mining preparation layout: The original project involved laying out main mining lines, ore access roads, and drilling tunnels in each segment of the ore body's base. Building upon this, the present invention constructs connecting tunnels to the intervening pillars at slopes of 5%-13% downwards and upwards from the main mining lines corresponding to each pillar segment. Each connecting tunnel is perpendicular to the ore body strike and is responsible for the mining of the pillars arranged along the strike on both sides. Backfill shafts are located on the hanging wall of the pillars and extend through the pillars to the access roads of each layer; backfilling can be carried out after the mining of each layer is completed.

[0034] Longwall mining: The longwall mining area is defined as the area encompassing half of the pillars between the main pillars and the top and bottom pillars on both sides. During longwall mining, a longwall connecting road is laid from the main mining line to the vertically oriented pillar. When the vertically oriented pillar is mined to the strike-oriented pillar, the mining direction shifts to the strike-oriented pillar within the longwall mining area. After the strike-oriented pillar within the longwall mining area is mined, backfilling is carried out. Subsequently, the vertically oriented pillar is mined again.

[0035] The pillar adopts single-step layered mining. The first layer is mined to a height of 5m, and the other layers are mined to a height of 4m. After the first layer is mined, the filling height is 3m, and a 2m high space is reserved as compensation space for shallow hole blasting during upward layered mining.

[0036] Once the backfill material reaches the required strength, upward stratified mining can begin. During upward stratified mining, the outer mining tunnel needs to be raised by brushing the top and using raised surrounding rock slag as a base to form the upward stratified mining tunnel.

[0037] Backfilling: The strips are filled with tailings and waste rock without cementation, while the surface layer is filled with cementation. The thickness of the cemented surface layer is 0.5m, and the compressive strength of the surface layer after 7 days is 1.5MPa.

[0038] Example 2

[0039] The method for mechanized segmented open-cut subsequent backfilling pillar mining as described in this embodiment includes the following steps:

[0040] Pillars, access strips structure and parameters: Pillars are arranged perpendicular to and along the strike of the ore body. The strips are arranged according to the strike of the pillars. The pillars are 5m wide and 20m thick vertically. The access strips are layered with a height of 4m and a width of 4m. Each layer of access strips has 0.5m wide pillars reserved on both sides.

[0041] Preparation work layout: During the mining of the original process stope, preparation main lines, ore access roads, and drilling adits are arranged in each section of the ore body base. Using the existing preparation main lines corresponding to the pillar positions, mining access roads are constructed to the intervening pillars at downward and upward slopes of 5%-13%. Each mining access road is responsible for half of the mining area of ​​the pillars arranged along the strike on both sides. Backfill shafts are arranged in the hanging wall of the pillars and can be used for backfilling after each layer of mining is completed.

[0042] Longwall mining: The longwall mining area is defined as half of the inter-pillar and the top and bottom pillars on both sides. During longwall mining, a longwall connecting road is laid from the main mining line to the vertically striking pillar. When the vertically striking pillar (inter-pillar) is mined to the strike pillar, the mining direction shifts to the strike pillar within the longwall mining area. After the strike pillar (top and bottom pillar) within the longwall mining area is mined, backfilling is carried out. Then, the vertically striking pillar is mined again.

[0043] The upward-layered mining method involves mining the first layer at a height of 5m. Other layers are mined by excavating and cutting roadways or by blasting to fill the space reserved during the filling of the previous layer, with a layer height of 4m. After the first layer is mined, the filling height is 3.5m, and a 1.5m high space is reserved as compensation space for shallow-hole blasting during upward-layered mining.

[0044] Once the backfill material reaches the required strength, upward stratified mining can begin. During upward stratified mining, the outer mining tunnel needs to be raised by brushing the top and using raised surrounding rock slag as a base to form the upward stratified mining tunnel.

[0045] Backfilling: The strip is backfilled with tailings and waste rock without cementation, while the surface layer is backfilled with cementation. The cemented surface layer is 0.5m thick and has a 7-day compressive strength of 2MPa. The first layer has a mining height of 5m and a backfilling height of 3.5m.

[0046] Example 3

[0047] A method for mechanized segmented open-cut subsequent backfilling pillar mining includes the following steps:

[0048] Pillar layout: Based on the layout and mining method of the stope with subsequent backfilling, the pillars are arranged vertically and along the strike. The pillars are 8m wide and have an average vertical thickness of 21m.

[0049] Layout of Preparatory Works and Division of Mining Areas: In the original open-stope backfilling method, during the mining process, preparatory trunk lines, ore access roads, and bottom drilling roadways are arranged at the bottom of each sub-section of the stope. For pillar mining, the preparatory trunk lines from the original mining process are used to connect to the pillars at corresponding locations with slopes of 5-13%, extending downwards and upwards to the vertically oriented pillars. Access strips are arranged at the bottom of the pillars for their mining. Each vertically oriented pillar and half of the adjacent pillars along the strike on both sides constitute a mining area, reducing transportation distance and improving mining efficiency. The access strips are 6m wide, with a first-layer mining height of 5m, an upper-layer mining height of 4m, and 1m thick sidewalls reserved on each side.

[0050] Mining and backfilling: Based on the dimensions of the access strip structure, upward layered mining is adopted. The first layer of mining is 5m high. After mining, the backfilling height is 3.5m, with a 1.5m margin reserved for upward mining. The bottom layer consists of 3m thick non-cemented end sand and the surface layer is 0.5m thick cemented backfill, with a 7-day surface layer compressive strength of 2MPa. During the upper layer mining, the backfilling depth is 2.5m, continuing until mining reaches the roof for joint backfilling.

[0051] During each layer of mining, based on the division of the mining area in the previous steps, the pillars between the layers are mined first. When the pillars are mined to the top and bottom pillar positions, mining stops, and mining is switched to mining along the bottom pillar. After the mining and backfilling are completed, mining continues until the pillars are encountered.

[0052] After each layer of mining and backfilling is completed, the top of the external mining tunnel is raised and the collapsed rock debris is compacted and leveled to create conditions for the mining of the upper layers.

[0053] In summary, the present invention employs a strip-path upward layered mechanized segmented open area subsequent filling method to leave ore pillars. These pillars are divided into top and bottom pillars (along the strike of the ore body) and inter-pillars (perpendicular to the strike of the ore body). Adjacent inter-pillars and top and bottom pillars are mined as a single mining unit, thus saving on the amount of preparation work.

[0054] An upward-facing, layered mining method was adopted to control the exposure height of the tailings backfill on both sides. Due to the low cohesion of the tailings backfill, the lateral exposure surface needs to be controlled within a certain height; otherwise, tailings collapse would not only lead to significant ore dilution but also pose safety issues. Considering the stability of the tailings sidewalls, a 0.5-0.7m ore wall was left between the strip approach and the backfill.

[0055] The layered mining technology used in this invention involves arranging a strip approach in each layer. After the mining of a layer is completed, the strip is non-cemented and filled to a height of 3.5m, and then a 0.5m surface layer is cemented and filled, thereby achieving safe and low-depletion mining of resources.

[0056] Backfilling technology can reduce the environmental risks and the incidence of geological disasters in mining. Backfilling is a post-mining treatment technology that fills the voids left by mining, thereby reducing damage to the geological environment and the incidence of geological disasters. This invention employs backfilling technology, performing backfilling after each layer of mining is completed, and arranging backfill wells on the hanging wall of the strip, thereby reducing the impact of the mine on the geological environment and the incidence of geological disasters.

[0057] The use of modern mining equipment can improve mining efficiency and reduce mining costs. Mining equipment is a key component of mining operations; modern equipment not only improves efficiency but also reduces costs, thus enabling sustainable development of mines. This invention primarily utilizes a loader to extract ore in the main stope, transporting it to a sectional pass. The ore then reaches the intermediate section via the pass and is subsequently transported to the main shaft hoisting system by rail-guided equipment. In areas or sections farther from the pass, 15-20 ton trucks can be used in conjunction with the loader for ore extraction. The use of modern mining equipment enhances mining efficiency, reduces costs, and promotes sustainable mine development.

[0058] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for mechanized segmented open-cut subsequent backfilling pillar mining, characterized in that: Includes the following steps: S1: Pillar mining unit division: The pillars are arranged according to the block layout of the subdivided open area subsequent filling mining method. The pillars are arranged as inter-pillars perpendicular to the ore body and top and bottom pillars along the ore body. Two adjacent inter-pillars and the bottom pillar between them constitute a mining unit. The pillars are layered vertically in the strip entry direction, and a certain width of ore wall is reserved on both sides of the strip entry. S2: Mining preparation engineering layout: At the location of the mining preparation trunk line corresponding to each section pillar, construct the mining connecting road to the inter-pillar at a downward slope of 5%-13%, and then arrange the mining access road in the pillar with a flat slope. The mining access roads arranged in adjacent inter-pillars and the mining access roads in the top and bottom pillars are interconnected to form a safety exit and ventilation flow. At the same time, set up raises or filling boreholes in appropriate locations in the pillar to the upper hanging wall of the ore body to fill the return air system. S3: Mining and Backfilling: Single-step upward layered mining is adopted, with one strip access road arranged in each layer. During the mining process, the roof is supported by anchor bolts or anchor bolt + anchor mesh support according to the stability of the roof. After the mining of a layer is completed, the strip is backfilled to a height of 3.5m using non-cemented backfilling, and then 0.5m of surface cemented backfilling is carried out. As the mining layers rise, the mining access road is gradually raised by brushing the top and using the raised surrounding rock to raise the bottom plate, forming mining access roads that lead to each layer. At this time, the corresponding drilling roadways and ore extraction access roads at the lower part will be backfilled.

2. The method for mechanized segmented open-cut subsequent backfilling pillar mining according to claim 1, characterized in that, In step S1, the width of the strip is determined according to the width of the mined pillar, which is 4.3-4.5m, and the height is 4-5m. A 0.5-0.7m wide ore wall is left between the strip entrance and the stope filling body.

3. The method for mechanized segmented open-cut subsequent backfilling pillar mining according to claim 1, characterized in that: In step S2, the bottom layer of the strip is filled with tailings and waste rock, followed by a 0.5m thick cemented surface layer with a compressive strength of 1.5-2 MPa. Filling wells are arranged in the pillars to the strip access layer, and filling is carried out after each layer is mined.

4. The method for mechanized segmented open-cut subsequent backfilling pillar mining according to claim 1, characterized in that: In step S3, after the first layer of mining is completed, the filling height is 3-3.5m, leaving a height of 1.5m as the free face and compensation space for the upper layer blasting.

5. The method for mechanized segmented open-cut subsequent backfilling pillar mining according to claim 1, characterized in that: Ore is removed by a loader and transported to a sectional pass. The ore then reaches the middle section via the pass and is transported to the main shaft hoisting system by rail equipment in the middle section. In areas or sections far from the pass, 15-20t trucks are used in conjunction with loaders to remove ore.

6. The method for mechanized segmented open-cut subsequent backfilling pillar mining according to claim 1, characterized in that: The mining method employs an upward layered backfilling approach, with the mining face being a single-ended roadway. A combination of extraction and pressure ventilation is used, with waste air entering the return air system from the segmented mining preparation trunk line.

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