A two-step upward inclined slicing and filling mining method with reserved retaining wall

Abstract

The application provides a reserved retaining wall type two-step upward inclined sublevel filling mining method, and belongs to the technical field of mining engineering, which comprises the following steps: dividing a mining block into multiple inclined sublevels along the ore body inclination, and dividing the mining block into one-step ore rooms and two-step ore pillars along the ore body strike; constructing a preparation cutting engineering; performing sublevel stoping on the one-step ore rooms from bottom to top, reserving a primary ore body retaining wall on the sublevel roof after each sublevel stoping is completed; performing cemented filling on the mined-out area after single sublevel stoping is completed, so that the filling body formed by cementation is connected with the retaining wall; after the one-step ore rooms are completely stoped and filled, the two-step ore pillars are stoped according to the same process, so that a two-step alternate stoping cycle is formed. The technical scheme has the technical effect of improving the stability of the stope.

Description

Technical Field

[0001] This application relates to the field of mining engineering technology, specifically to a two-step upward inclined layered filling mining method with reserved retaining wall. Background Technology

[0002] Dipping, medium-thick ore bodies are typically mined using the room-and-pillar method. However, this traditional method requires numerous continuous pillars to control the stability of the surrounding rock and prevent roof collapses and spalling. This not only leaves a large amount of mineral resources underground and unrecoverable, significantly increasing mining losses, but also results in large exposed areas and excessively wide goafs in thick ore bodies, making conventional pillar support ineffective in controlling roof movement and posing a high risk of surrounding rock collapse and localized collapses. Furthermore, the traditional room-and-pillar method often employs a single-layer mining approach without layered or zoned mining logic. The large thickness of a single mining operation in a thick ore body makes blasting, ore extraction, and support operations difficult, compromising stope stability. Summary of the Invention

[0003] In view of the technical problems existing in the background art, this application provides a two-step upward inclined layered backfilling mining method with reserved wall support, including: The mining block is divided into multiple inclined layers along the dip of the ore body, and further divided into first-stage stopes and second-stage pillars along the strike of the ore body. Construction preparation and cutting work; The first-stage stope is mined in layers from bottom to top. After each layer is mined, the original ore body is reserved on the top plate of the layer to protect the wall. After the single-layer mining is completed, the goaf is cemented and backfilled so that the cemented backfill body is connected to the retaining wall. After the first-step stope is fully mined and backfilled, the second-step pillar is mined using the same process, forming a two-step alternating mining cycle.

[0004] Furthermore, the construction preparation and cutting process includes: The connecting roadway at both ends of the ore block was excavated to penetrate the ore body; The cutting tunnel is excavated along the footwall of the ore body, and at the center of the cutting tunnel, the cutting tunnel is then excavated upwards along the bottom plate of the ore body. Excavating the upper ventilation connecting roadway and the upper pedestrian ventilation roadway of the mining area; The ore extraction equipment is installed in an electric scraper chamber, which is at the same elevation as the cutting level roadway and is connected to the cutting level roadway.

[0005] Furthermore, the stratified recovery includes: Using the cutting uphill as the free face and compensation space, a retreating mining sequence from top to bottom is adopted. First, the top is pressed and trimmed to the layer boundary while retaining the roof wall, and then the side walls are expanded to the designed mining width.

[0006] Furthermore, after ore extraction, differentiated support is adopted according to the stability of the surrounding rock. In stable areas, anchor bolt support is adopted, in moderately stable areas, anchor mesh combined support is adopted, and in broken and weak areas, anchor spraying or concrete support is adopted.

[0007] Furthermore, except for the top layer, the remaining layers are filled with high-strength cemented filling slurry; in the top layer, the first-stage stope is filled with high-strength cemented filling, and the second-stage pillar is filled with low-strength cemented filling, tailings or waste rock.

[0008] Furthermore, the adhesive filling includes: A filling retaining wall is constructed on the inner wall of the cutting tunnel near the goaf to seal off the goaf. Cemented backfilling is carried out in the upper pedestrian ventilation roadway into the goaf.

[0009] Furthermore, after the mining of this layer is completed, a hanging wall haulage roadway is constructed in the next layer of ore body, and the hanging wall haulage roadway is connected to the intermediate connecting roadway. Construct a filling retaining wall in the middle transport roadway to seal off the cutting level roadway and electric scraper chamber in the upper layer; Cemented filling is carried out on the cutting level tunnel and electric scraper chamber in the next layer.

[0010] Furthermore, in the first-stage stope of the first-stage stope, the center of the stope is expanded and slashed for mining based on the cutting uphill. After the mining is completed, a high-strength backfill body is used for backfilling and maintenance. After the maintenance is completed, the second layer of the central area in the first-step ore stope is excavated, cut, and expanded for mining, while the backfilling operation is completed simultaneously. After the first-stage stope is fully mined and backfilled, the second-stage pillar is mined using the same process, advancing layer by layer upwards until the entire middle section of the ore body is mined out.

[0011] Furthermore, the two-step alternating mining cycle is carried out alternately between each layer. When the lower layer is carrying out the first-step stope mining, the upper layer is simultaneously carrying out the second-step pillar mining operation, and the second-step pillar is used as the first mining site of the upper layer.

[0012] Furthermore, a top pillar is left in the upper part of the mining area, and the bottom pillar is eliminated during the mining process.

[0013] In the technical solution provided in this embodiment, a continuous ore body that has not been damaged by blasting is retained on the roof of the goaf by reserving the original ore body retainer. This retainer is connected to the overlying and surrounding ore and rock, and has good integrity and high tensile and shear strength, so as to improve the roof stability of the inclined medium-thick ore body stope. At the same time, by dividing the ore block into a first-step stope and a second-step pillar along the strike, it is a two-step mining layout of mining the stope first and then mining the pillar, which reduces the exposed area of ​​a single stope, thereby further improving the stability of the stope.

[0014] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0016] Figure 1 This is a cross-sectional schematic diagram of a mining area structure provided in an embodiment of this application; Figure 2 A cross-sectional schematic diagram of the second layer of a mining area structure provided in an embodiment of this application; Figure 3 for Figure 1 Schematic diagram of the structure of the middle BB section; Figure 4 for Figure 1 A schematic diagram of the structure of the CC section.

[0017] Explanation of reference numerals in the attached diagram: 1. Intermediate connecting roadway; 2. Ore body; 3. Cutting uphill; 4. Electric scraper chamber; 5. Collapsed ore; 6. Filling body; 7. Cutting level roadway; 8. Filling retaining wall; 9. Upper-middle connecting roadway; 10. Upper-middle transport roadway; 11. Upper pedestrian ventilation roadway in the stope; 12. External transport roadway; 13. Footing along the vein transport roadway; 14. Footing along the vein transport roadway; 15. Wall protection. Detailed Implementation

[0018] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0020] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0023] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0024] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0025] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0026] Understandably, inclined medium-thick ore bodies are typically mined using the room-and-pillar method. In traditional room-and-pillar mining of inclined medium-thick ore bodies, to control the stability of the surrounding rock of the stope and prevent roof collapses and spalling disasters, a large number of continuous pillars need to be reserved within the stope. This not only results in a large amount of mineral resources remaining underground and unrecoverable, significantly increasing the mining loss rate, but also, due to the large exposed area and excessive span of the goaf in thick ore body mining, conventional pillar support is insufficient to effectively control the movement of the roof strata, leading to extremely high risks of surrounding rock collapse and localized collapse. Furthermore, traditional room-and-pillar methods often employ a single-layer mining model without a layered or zoned mining logic. The large thickness of a single mining operation in a thick ore body makes blasting, ore extraction, and support operations extremely difficult.

[0027] While the existing upward horizontal layered filling mining method has the advantages of filling support and high resource recovery rate, this process is based on horizontal layering and is suitable for mining near-horizontal ore bodies. When applied to inclined medium-thick ore bodies, its layering fit is poor and the filling is not dense at the top.

[0028] To address the above technical problems, this application provides a two-step upward inclined layered backfilling mining method with reserved wall support, comprising: S1. Divide the mining block into multiple inclined layers along the dip of the ore body, and further divide it into first-step stopes and second-step pillars along the strike of the ore body. S2, Construction preparation and cutting engineering; S3. The first-stage stope is mined in layers from bottom to top. After each layer is mined, the original ore body is reserved on the top plate of the layer for protection. S4. After the single-layer mining is completed, the goaf is cemented and backfilled so that the cemented backfill body is connected to the wall. S5. After the first-step stope has been completely mined and filled, the second-step pillar is mined using the same process, forming a two-step alternating mining cycle.

[0029] The technical solution of this embodiment divides the ore block into a first-stage stope and a second-stage pillar, and adopts an inclined stratified mining method along the dip of the ore body. This adapts the stratification to the ore body's occurrence morphology, improving the backfilling and roof connection effect. Simultaneously, by reserving the original ore body wall during stratified mining, the backfill and wall are connected to form a composite load-bearing structure, which improves the integrity and stability of the stope roof and reduces the risk of roof delamination and collapse caused by insufficient backfill strength or lack of roof connection. Furthermore, using the cemented backfill of the first-stage stope as an artificial pillar for subsequent second-stage pillar mining can improve ore recovery while forming an alternating two-stage mining cycle, balancing stope production pressure.

[0030] In the technical solution provided in this embodiment, a continuous ore body undamaged by blasting is preserved in the roof of the goaf by reserving a retaining wall for the original ore body. This retaining wall is connected to the overlying and surrounding ore and rock, possessing good integrity and high tensile and shear strength, thereby improving the roof stability of the inclined medium-thick ore body stope. Simultaneously, by dividing the ore block along the strike into a first-step stope and a second-step pillar, a two-step mining layout of first mining the stope and then mining the pillar reduces the exposed area of ​​a single stope, further enhancing stope stability. Before the backfill reaches its design strength, the retaining wall acts as a direct load-bearing component, bearing the load of the overlying strata and limiting roof deformation. At the same time, the retaining wall isolates the stope operations from direct contact with the backfill, preventing subsequent blasting vibrations and ore extraction disturbances from damaging the early backfill and reducing phenomena such as cracking and delamination of the backfill. Once the backfill reaches its designed strength, it adheres to the lower surface of the retaining wall to form a composite structure, providing support and lateral restraint for the retaining wall. The retaining wall then transfers the overlying load to the backfill, which in turn distributes the load to the side walls and the substructure. This compensates for the shortcomings of a single backfill, such as low early strength, easy shrinkage, and lack of roof support. It also improves the stress state of the roof and enhances the stability of the stope during the next layer of mining and the mining of adjacent stops. This provides conditions for appropriately increasing the stope span and reducing the amount of roof support work.

[0031] This can be understood as follows: the stratification of this scheme is parallel to the dip angle of the ore body. After each layer is mined, an inclined goaf is formed, with the roof being the inclined original ore body retaining wall. After backfilling, the top surface of the backfill is an inclined surface with the same dip angle, directly adhering to the lower surface of the retaining wall. This surface also serves as the working floor for the previous layer of mining. Compared to the problem of horizontal voids remaining at the top in horizontal stratification, the slurry naturally accumulates on an inclined slope consistent with the dip direction of the ore body, achieving full adhesion between the backfill and the lower surface of the retaining wall, thus improving the compactness of the backfill at the roof.

[0032] It can be explained that inclined stratification refers to the division of mining units along the dip of the ore body at a certain vertical height. The stratification height is determined based on the drilling equipment capacity, backfilling process characteristics, and the stability of the ore and rock, and is usually 2m to 4m. Dividing the ore block along the strike into a first-stage stope and a second-stage pillar is a two-stage mining layout where the stope is mined first, followed by the pillars. After the first-stage stope backfill solidifies, it forms an artificial pillar, providing lateral support for the second-stage pillar mining, thereby achieving full recovery of ore resources.

[0033] It can be explained that preparatory cutting engineering is a shaft and tunnel engineering project that prepares free faces, blasting compensation space, and ore extraction and ventilation channels for stratified mining. It typically includes intermediate connecting roadways, cutting level roadways, and cutting inclines. The bottom-up stratified mining sequence refers to starting from the inclined layer at the bottom of the ore block and advancing layer by layer upwards, using the already filled goaf in the lower part as the working platform for the mining of the next layer. At the same time, the filled body can provide support for the overlying strata and control the manifestation of ground pressure.

[0034] It can be explained that primary ore body retaining wall refers to the practice of leaving a layer of ore body on the roof of each mining layer without blasting, typically 1m to 2m thick. The retaining wall remains connected to the overlying ore layer, maintaining the integrity of the roof. After each layer is mined, cemented backfill is carried out in the goaf. Once the backfill slurry solidifies, it adheres to or bonds with the lower surface of the retaining wall, forming a mechanical connection. As primary ore body, the retaining wall has higher stiffness and strength than the earlier backfill, controlling initial roof displacement. The backfill shares the load during later load-bearing, constraining the lateral and longitudinal deformation of the retaining wall to achieve better long-term load-bearing performance.

[0035] By employing a two-step upward inclined layered filling mining method with reserved wall in the mining of inclined medium-thick ore bodies, the inclined layering improves the fit between the layer and the ore body morphology, improves the roof connection conditions of the filling, and forms a composite roof structure by connecting the reserved original ore body wall with the filling body. The mechanical properties of the original ore body itself compensate for the weakness of insufficient early strength of the filling body, thereby improving the stability of the stope during multi-layer mining and the mining of adjacent stops.

[0036] In some implementations, S2, the construction preparation and cutting process includes: S201, Excavate the middle section connecting roadway at both ends of the ore block to penetrate the ore body; S202. Excavate the cutting tunnel along the footwall of the ore body, and at the center of the cutting tunnel, diagonally excavate and cut upwards along the bottom plate of the ore body. S203, the upper ventilation connecting roadway and the upper pedestrian ventilation roadway of the mining area; S204. An electric scraper chamber is installed to house the ore extraction equipment. The electric scraper chamber is at the same elevation as the cutting level roadway, and the electric scraper chamber is connected to the cutting level roadway.

[0037] In this embodiment, a connecting roadway is excavated at both ends of the ore block to penetrate the ore body, forming a connecting channel between the ore block and the main transport roadway, providing a passage for subsequent ventilation, ore extraction, and material transportation. A cutting horizontal roadway is excavated along the footwall of the ore body, and a cutting incline is excavated upwards along the ore body floor at the center of the cutting horizontal roadway. This creates an initial free face and blasting compensation space before the inclined layered mining, enabling the first layer to meet blasting conditions. The cutting incline is arranged inclined upwards along the ore body floor, adapting to the mining direction of the inclined layers, providing continuous free faces for each layer, and reducing the workload of excavating cutting slots for subsequent layers. Simultaneously, by installing electric scraper chambers at the same elevation as the cutting horizontal roadway and interconnected with each other, the electric scraper chambers are positioned at a relatively low elevation within the stope, allowing the ore body to flow naturally from the inclined stope surface, reducing the workload of electric scraper ore transportation, and thus improving work efficiency.

[0038] It can be explained that the intermediate connecting roadway is a through-vein roadway that is excavated from the intermediate transport roadway towards the ore body. Its function is to connect the ore block with the intermediate transport system. Intermediate connecting roadways are arranged at the upper and lower ends of the ore block, with one end serving as the intake air side and the main transport channel, and the other end serving as the return air side and the safety exit.

[0039] It can be explained that the intravein cutting tunnel is excavated along the footwall of the ore body, with its strike consistent with the ore body's strike. It serves as the ore extraction channel and blasting compensation space for layered mining. At the center of the cutting tunnel, an upward cutting incline is excavated along the ore body floor, with the incline angle matching the ore body's dip angle, forming an initial free face in the diagonal direction. During the first layer of mining, blasting is performed to widen the slope using the cutting incline as the free face and compensation space. Subsequent layers can utilize the surface of the lower filled body as a working platform to continue extending the cutting incline upwards or directly use the filled body surface as a reference for mining.

[0040] It can be explained that the electric scraper chamber is a chamber used to house ore extraction equipment such as electric scraper winches. Its location is at the same elevation as the cutting level roadway and is directly connected to the cutting level roadway.

[0041] It can be explained that the upper ventilation connecting roadway and the upper pedestrian ventilation roadway of the mining area are located at the upper boundary of the ore block, and are connected to the middle connecting roadway at both ends and the cutting uphill to form a return air system.

[0042] In some implementations, S3, the first-stage stope is mined in layers from bottom to top, and after each layer is mined, a retaining wall for the original ore body is reserved on the top plate of the layer, including: S301. Taking the cutting uphill as the free face and compensation space, the retreat mining sequence is adopted from top to bottom. First, the top is pressed and trimmed to the layer boundary and the roof is retained to protect the wall. Then, the side walls are expanded to the designed mining width.

[0043] In this embodiment, the layered mining method uses the cutting of the incline as the initial free face and compensation space, and adopts a backward mining sequence from top to bottom along the inclined direction. First, the layered roof is pressed down and trimmed to the designed layer boundary. During this process, the roof retaining wall is retained according to the designed thickness without blasting, so that the retaining wall remains connected to the overlying ore layer. After the roof pressing is completed, the side expansion mining is carried out on both sides to the designed mining width, based on the formed roof boundary. This construction sequence of pressing down the roof first and then expanding the side ensures that the reserved roof retaining wall is completed before the side expansion blasting, which can form a controlled goaf space below the retaining wall, avoiding direct damage to the integrity of the retaining wall by the side expansion blasting. At the same time, the regular roof outline formed by the roof pressing operation provides a reference benchmark for the uniform control of the retaining wall thickness, reducing the occurrence of insufficient thickness or over-excavation of the retaining wall in some areas. The retreating mining sequence allows the working face to advance towards the stope entrance. The collapsed ore slides down the inclined floor under the action of gravity and accumulates near the cutting level, which facilitates the centralized scraping and transportation by ore-extracting equipment such as electric scrapers, reducing the dead corners in ore extraction and the amount of secondary crushing work caused by the scattered accumulation of ore in the stope.

[0044] It can be explained that the cutting incline, serving as a free face and compensation space, is an inclined roadway excavated upwards along the bottom plate of the ore body during the pre-mining cutting stage. During the first layer of mining, the cutting incline provides an initial free face for blasting, allowing the blasting stress wave to act in the direction of the free face, resulting in a better fracturing effect. At the same time, it provides expansion and displacement space for the blasting gas and the fractured ore and rock.

[0045] It can be explained that the top-down retreat mining sequence refers to the gradual advancement of mining along the dip direction of the ore body, from the higher to the lower levels of the strata. Under inclined stratification conditions, this sequence allows the collapsed ore to slide down the dip surface by its own weight and accumulate in the lower cutting level area, creating a concentrated ore pile for electric scraper mining.

[0046] To clarify, "top sealing and shaping to the layer boundary" refers to the process of drilling and blasting the layered roof area before the expansion and mining phase, shaping the roof to the designed elevation and boundary outline. During top sealing operations, the drilling depth and charge amount are controlled according to the designed retaining wall thickness, ensuring that after blasting, a layer of primary ore body connected to the overlying ore layer remains as a retaining wall. The retaining wall thickness is determined based on factors such as the stability of the roof rock and the span of the layers. Top sealing blasting employs controlled blasting techniques such as smooth blasting or pre-splitting blasting to maintain the integrity and continuity of the retaining wall. After top sealing is completed, the roof forms a regular outline, providing a clear working boundary for subsequent expansion and mining.

[0047] It can be explained that expanding the stope to the designed width on both sides refers to gradually widening the stope by blasting outwards from the sides of the stope after the roof boundary is formed by the roof compression, using the roof outline as a reference, until the designed stope width is reached. Extending the stope can be done using horizontal or vertical shallow holes. During the extension process, the pre-reserved roof retaining wall serves as temporary roof support to protect the safety of the working space below. After the extension is fully completed and ore is extracted, the goaf is uniformly cemented and backfilled.

[0048] In some implementations, S3, bottom-up stratified mining of a one-step stope, further includes: S401. After mining, differentiated support is adopted according to the stability of the surrounding rock. In stable areas, anchor bolt support is adopted; in moderately stable areas, anchor mesh combined support is adopted; and in broken and weak areas, anchor spraying or concrete support is adopted.

[0049] In this embodiment, differentiated support is implemented based on the stability of the surrounding rock after ore extraction. Support measures matching the risk level can be adopted according to the actual surrounding rock conditions of different sections, ensuring the safety of stope operations while reasonably controlling support costs. This provides a stable working space and regular goaf boundary conditions for subsequent backfilling operations. During inclined layered mining, the two sides of the stope in the first step are the primary ore body and the pillars in the second step, respectively. The stope roof is a reserved primary ore body retaining wall. The ore and rock in different sections exhibit different stability states due to differences in joint development, tectonic influence, and stress distribution. By employing differentiated support methods, anchor bolts are used to point-suspend and reinforce the roof retaining wall in stable areas, controlling the tendency for delamination. In moderately stable areas, metal mesh is added to form a combined anchor-mesh support system. The mesh can protect loose rock fragments between the anchor bolts, preventing small pieces from falling and causing injury. In fractured and weak areas, shotcrete or concrete support is used. Shotcrete can seal surface cracks in the surrounding rock, isolate the weathering effect of air and moisture on the surrounding rock, and form a thin-shell structure with a certain compressive strength, which, together with the anchor bolts, restrains the deformation of the surrounding rock. This demand-based, tiered support scheme allows support resources to be concentrated in high-risk areas, ensuring operational safety while avoiding the increased engineering costs and construction delays caused by full-section reinforced support.

[0050] In some implementations, S4, after the completion of single-layer mining, the cemented backfilling of the goaf includes: S501. Except for the top layer, the other layers are filled with high-strength cemented filling slurry; in the top layer, the first-stage stope is filled with high-strength cemented filling, and the second-stage pillar is filled with low-strength cemented filling, tailings or waste rock.

[0051] In the technical solution of this embodiment, by implementing differentiated filling strength schemes in different layers and different mining steps, the strength of the filling body can be adapted to the actual stress requirements. High-strength cemented filling bodies are concentrated in layers and stops with higher load-bearing requirements. Under the premise of meeting safety requirements, the filling cost of the top layer two-step pillar is reduced, and the filling material resources are rationally allocated.

[0052] Except for the top layer, the remaining layers serve as working platforms for subsequent mining and lateral supports during the mining of adjacent stops. They need to withstand the equipment loads from the upper mining operations, blasting vibrations, and lateral pressures generated during the mining of adjacent stops. Filling these layers with high-strength cemented backfill slurry allows the backfill to reach high strength in a short time, meeting the load-bearing requirements for personnel and equipment working above it during the mining of the next layer. Simultaneously, it provides lateral support for the second-stage pillar mining, limiting the deformation and damage of the backfill under lateral pressure. The top layer is located at the upper boundary of the stope. Its filling body in the first-stage stope needs to serve as the roof support structure during the second-stage pillar mining. It is required to have high strength to ensure the roof stability when the second-stage pillar mining reaches the end stage. In the top layer of the second-stage pillar, there is no mining operation above the filling body. Its main function is to fill the goaf, control surface subsidence and surrounding rock movement. The strength requirement is reduced. Low-strength cemented filling, whole tailings or waste rock filling can be used to reduce the amount of cementing material and reduce filling costs.

[0053] In some implementations, S4, after the completion of single-layer mining, the cemented backfilling of the goaf includes: S601. Construct a filling retaining wall on the inner wall of the cutting level roadway near the goaf to seal off the goaf. S602. Cemented backfilling is carried out in the upper pedestrian ventilation roadway of the mining area into the goaf.

[0054] In this embodiment, the process of constructing a backfilling retaining wall within the cutting level tunnel to seal the lower entrance of the goaf, and then conveying backfilling slurry from the upper ventilation tunnel of the stope for cemented backfilling, allows the backfilling slurry to accumulate and solidify in a controlled manner within the enclosed space, forming a backfill body connected to the retaining wall. This provides a support platform for the next layer of mining operations, while ensuring the unobstructed flow of external roadways and operational safety during the backfilling process. Cemented backfilling involves constructing a backfilling retaining wall on the inner wall of the cutting level tunnel near the goaf to seal the lower entrance of the goaf, and injecting cemented backfilling slurry into the goaf from the upper ventilation tunnel of the stope, forming a closed backfilling operation path from bottom to top or from top to bottom. The cutting level tunnel is the ore outlet channel for layered mining. After mining is completed, this channel is directly connected to the goaf. If it is not sealed, the backfilling slurry will leak from the lower entrance and cannot accumulate and form a solid structure within the goaf. Constructing a backfill retaining wall on the side of the cutting roadway adjacent to the goaf can seal the lower boundary of the goaf, providing bottom support for the backfill slurry and allowing it to remain and gradually solidify within the goaf. Simultaneously, the upper ventilation roadway of the stope, located at the upper boundary of the ore block and connected to the upper goaf, allows backfill slurry to be transported into the goaf. The slurry can be used to fill the goaf by its own weight flowing downwards along the inclined direction, or it can be pumped upwards through pipelines, filling the upper space of the goaf and improving the compactness of the backfill.

[0055] Understandably, this process is the main filling process for single-layer goaf areas, and it is executed after each layer of ore is mined out.

[0056] In some embodiments, the pre-retained wall type two-step upward inclined layered backfilling mining method also includes: S701. After the mining of this layer is completed, the hanging wall haulage roadway is constructed in the next layer of ore body. The hanging wall haulage roadway is connected to the intermediate connecting roadway. S702. Construct a filling retaining wall in the middle transport roadway to seal off the cutting level roadway and electric scraper chamber in the upper layer; S703, perform cemented filling of the cutting level tunnel and electric scraper chamber in the next layer.

[0057] In this embodiment, after the current layer is mined, an upper hanging wall haulage roadway is constructed in the next ore body and connected to the intermediate connecting roadway. This provides a new haulage channel for subsequent layers, replacing the ore extraction function of the lower, filled and sealed cutting level roadway. The upper hanging wall haulage roadway is located on the hanging wall side of the ore body, corresponding to the cutting level roadway on the footwall side. It is connected by the intermediate connecting roadway to form a haulage network, allowing the ore transport path to move upwards synchronously with the upward movement of the mining face, maintaining the continuity and smooth flow of the ore extraction system. Simultaneously, a backfilled retaining wall is constructed within the intermediate haulage roadway to seal the cutting level roadway and electric scraper chamber left over from the previous layer, and cemented backfilling is implemented. This eliminates the hidden dangers of cavities formed by abandoned roadways and reduces the adverse impact of excessively large goaf connectivity areas on the overall stability of the stope.

[0058] It can be noted that the cutting level roadways and electric scraper chambers in the upper layer are abandoned after mining is completed. If they are not backfilled, these roadway spaces will form long-term cavities, which may become stress concentration points, causing local instability during the transfer of loads from the upper part of the stope. They may also become channels for leakage of backfill slurry during the mining of adjacent stops. Constructing backfill retaining walls in the intermediate transport roadways to seal the entrances and exits of these abandoned roadways, and then performing cemented backfilling, can fill the abandoned roadway spaces, reduce the volume of cavities in the stope area, and help control the displacement and stress distribution of the upper strata in the stope.

[0059] Understandably, this process is a supplementary filling process for abandoned roadways. After the mining of this layer is completed and the ore extraction channel of the lower layer is switched to the upper plate along the vein transport roadway, the abandoned cutting level roadway and chamber of the lower layer are sealed and filled to reduce the risk of cavities.

[0060] In some implementations, S3, layered mining of the first-stage stope from bottom to top, and S5, mining the second-stage pillar using the same process after all the first-stage stope has been mined and filled, include: S801, the first layer of the first-stage stope in the first-step stope is expanded and slashed for mining based on the cutting uphill. After the mining is completed, high-strength backfilling body is used for backfilling and maintenance. S802. After the maintenance is completed, the second layer of the central area of ​​the first-step ore stope is excavated, cut uphill and expanded back mining is carried out, and the backfilling operation is completed simultaneously. S803. After the first-stage stope is fully mined and backfilled, the second-stage pillar is mined using the same process in a cyclical manner, advancing layer by layer upwards until the entire middle section of the ore body is mined out.

[0061] In this embodiment, the cutting incline already excavated at the center of the cutting tunnel during the preparation stage serves as a free face and compensation space. It is then expanded to both sides to the designed mining width. After mining is completed, high-strength cemented backfilling and curing are performed. Once the backfill strength reaches the designed curing standard, the cutting incline is re-excavated in the central area corresponding to the second layer. The bottom plate of this cutting incline becomes the top surface of the backfill in the first layer. The free face formed by the excavation continues to serve the expansion and mining of the second layer. Backfilling is carried out simultaneously after mining is completed. This mining method, in which a cutting incline is re-formed and expanded in the central area of ​​each layer, ensures that each layer has an independent free face and compensation space, without relying on the space reserved in the previous layer or unfilled voids. The mining conditions for each layer are relatively independent and controllable. After each layer of backfill material has been cured to the required standard, the next layer of cutting and uphill excavation can proceed. The backfill material already possesses sufficient load-bearing strength to withstand the equipment loads and blasting vibrations during cutting, uphill excavation, and enlargement mining. This reduces the risk of cracking, subsidence, or uneven deformation of the backfill material that may occur when working on insufficiently solidified backfill material. After all the first-stage stope has been mined and backfilled, the formed backfill material serves as an artificial pillar, providing lateral support for the second-stage pillars to be mined using the same process. This process is continued layer by layer upwards until the entire intermediate ore body is mined, achieving the overall recovery of ore resources.

[0062] In some embodiments, the mortar-sand ratio of high-strength cemented filling grout is 1:4, and the mortar-sand ratio of low-strength cemented filling grout is 1:16.

[0063] In this embodiment, the high-strength cemented backfill slurry has a cement-to-sand ratio of 1:4, and the low-strength cemented backfill slurry has a cement-to-sand ratio of 1:16. These ratios are determined based on the differences in stress requirements of the backfill in each layer, while meeting the load-bearing requirements of the backfill. In the high-strength backfill slurry with a cement-to-sand ratio of 1:4, the amount of cementing material is relatively high. After solidification, the backfill can achieve higher compressive strength and cohesion, enabling it to remain self-sufficient during the mining of adjacent stops and preventing large-scale collapse. This provides reliable lateral support and roof support for the second-stage pillar mining. In the low-strength backfill slurry with a cement-to-sand ratio of 1:16, the amount of cementing material is significantly reduced. The backfill still retains a certain degree of integrity and volume filling function, meeting the requirements of the top-layered second-stage pillar backfill without subsequent load-bearing requirements, while simultaneously reducing cementing material consumption and backfilling costs.

[0064] It should be noted that the cement-sand ratio refers to the mass ratio of cementitious material to aggregate in cemented filling slurry. The cementitious material is usually ordinary Portland cement or mining-specific cementitious material, and the aggregate can be graded tailings, whole tailings, or crushed stone, etc. A cement-sand ratio of 1:4 means that 1 part cementitious material corresponds to 4 parts aggregate, and a cement-sand ratio of 1:16 means that 1 part cementitious material corresponds to 16 parts aggregate.

[0065] In some implementations, the two-step alternating mining cycle is carried out alternately between layers. When the lower layer is carrying out the first-step stope mining, the upper layer is simultaneously carrying out the second-step pillar mining operation, and the second-step pillar is used as the first mining site of the upper layer.

[0066] In the technical solution of this embodiment, by staggering the first-step and second-step mining operations between each layer, the mining of the second-step pillar is no longer limited by the completion time of the first-step stope in this layer. The number of mining sites that can be arranged simultaneously in the same block is increased, and the overall production capacity and mining efficiency of the block are improved.

[0067] It can be explained that, in this embodiment, the second-step pillar is used as the first mining site of the upper layer. This means that when the upper layer starts mining, the first thing to be mined is not the first-step stope of the layer itself, but its second-step pillar. It can also be understood that, in the projection of the lower layer in the direction from the upper layer to the lower layer, the first-step stope of the upper layer corresponds to the second-step pillar of the lower layer. Thus, during the mining of the first-step stope of the lower layer, the second-step pillar of the upper layer can be mined simultaneously, and the second-step pillar is used as the first-step stope of the upper layer for subsequent cyclic mining until the entire block is mined.

[0068] It can be explained that the pre-reserved original ore body retaining wall plays a role in bearing and isolating in this cross-layered staggered mining. When the upper two-step pillar is mined, the lower one-step stope thickens the roof through the retaining wall structure, thereby reducing the mutual disturbance between the upper two-step pillar and the lower one-step stope during the mining process, and improving the stope stability in synchronous mining.

[0069] In some implementations, the two-step upward inclined layered filling mining method with reserved wall also includes: leaving a top pillar in the upper part of the stope and eliminating the bottom pillar during the mining process.

[0070] In this embodiment, the practice of retaining a top pillar in the upper part of the stope and eliminating the bottom pillar during mining is an optimization of the stope structure based on the bottom-up mining sequence of inclined stratification and the bearing characteristics of the backfill. Eliminating the bottom pillar allows the mining of the lowest layer to be unrestricted by the amount of ore left in the bottom pillar, thus reducing the mining loss rate. In the bottom-up, layer-by-layer mining and backfilling process, the solidification of each lower layer of backfill forms a composite artificial floor, which provides load-bearing and support for the upper mining operations. The function of the bottom pillar as a protector of the lower roadways is replaced by the backfill. Retaining a top pillar in the upper part of the stope serves as a protective layer for the upper middle roadways, isolating the upper mining space from the upper middle roadways and preventing adverse effects of mining and backfilling activities on the stability of the upper roadways. Simultaneously, the top pillar can withstand the load of the overlying strata, reducing the pressure on the backfill directly bearing the entire load of the overlying strata.

[0071] In some implementations, refer to Figures 1 to 4 This application also provides an exemplary process for a pre-reserved wall type two-step upward inclined layered backfill mining method, including: 1. Stope layout and structural parameters For inclined medium-thick ore bodies with a thickness of 8-20m, this invention adopts a two-step upward inclined layered backfilling mining process with reserved protective walls. The ore body within the mining area of ​​the first and second steps is vertically divided into multiple layers along the dip direction, such as the first layer, the second layer, and above, and backfilling and mining operations are carried out sequentially. The core innovation of this invention is the setting of a reserved protective wall structure for the layered roof. After the mining of each layer is completed and before the mining of the next layer, a 1-2m thick original ore body protective wall 15 is reserved at the top of the layer. This protective wall is a permanent protective structure, which can effectively isolate the disturbance caused by the curing deformation and stress settlement of the lower backfill body, maintain the integrity and stability of the roof, significantly reduce the risk of high-altitude operations, and ensure the safety of layered mining operations.

[0072] Standardized layout of overall stope parameters: Each 60m section along the ore body strike is designated as an independent block. Within each block, stopes are arranged with alternating spans of 5-7m stopes and 5-7m pillars. A single block can accommodate six stopes, forming a regular two-step mining layout. The vertical height of the middle section of the mine is set at 30m, and the stope length matches the dip length of the upper and lower middle sections of the ore body. Bottom pillars are eliminated during mining to maximize the recovery of bottom mineral resources. Simultaneously, top pillars with a 3-4m width are uniformly installed at the top of the stope, forming a double protection system with the 1-2m layered roof retaining wall, comprehensively ensuring the stability of the surrounding rock.

[0073] 2. Layout of the preparation and cutting process The present invention features a well-organized, clearly layered, and well-ventilated cutting engineering layout. The specific engineering layout is as follows: An external transport roadway 12 opens into the ore block, and a mid-section connecting roadway 1 is excavated at both ends, penetrating the entire ore body 2. The roadway has a uniform cross-sectional specification of 3m × 2.8m², serving as the core passage for personnel, equipment transport, and the introduction of fresh air. Through the mid-section connecting roadway 1, a footwall internal cutting horizontal roadway 7 is excavated near the footwall of the ore body. The roadway cross-section is consistent with the connecting roadway, providing a working platform for mining and ore extraction operations.

[0074] At the center of the cutting horizontal roadway 7 within the lower plate, the cutting incline 3 is excavated diagonally upwards along the ore body floor, with a cross-section of 2.6m × 2.6m². This diagonal excavation proceeds to the elevation of the upper-middle section transport roadway 10, serving as the free face and ore compensation space for the first layer of mining in the first stage. After the first layer of mining and backfilling in the first stage is completed, the cutting horizontal roadway within the upper plate is excavated through the middle section connecting roadway 1, with the corresponding cutting incline constructed simultaneously. All cutting inclines 3 are interconnected via upper ventilation connecting roadways with a cross-section of 2m × 2m², and connected to the upper pedestrian ventilation roadway 11 in the stope, forming a complete closed-loop ventilation system. Simultaneously, an electric scraper chamber 4 is installed at the stope's supporting location to house the ore extraction equipment, ensuring the orderly operation of mechanized ore extraction.

[0075] 3. Mining process After all the pre-mining and cutting works have passed inspection, the layered mining operation will commence, following the principle of "first the stope, then the pillars, from bottom to top, inclined layering, wall protection, and backfilling as mining progresses." Initially, the first layer of stope will be excavated and backfilled using the cutting incline at its center. After backfilling, high-strength backfill will be used for curing. Once curing is complete, the second layer will be excavated and cut in the central area, with backfilling completed simultaneously. After all the first-stage stopes have been mined and backfilled, the second-stage pillars will be mined using the same process, advancing layer by layer upwards until the entire intermediate ore body is mined. Throughout each layer of mining, a 1-2m roof support wall will be maintained to strictly control roof disturbance and ensure operational safety.

[0076] 3.1 Rock drilling and blasting operations Rock drilling operations were carried out using a YT-28 rock drill. The cutting incline 3 at the center of the stope served as the blasting free face and compensation space. A retreating mining sequence was employed, proceeding downwards along the cutting incline. During construction, the cutting incline was first reinforced with roof control, trimmed to the designed stratified boundaries, and a 1-2m thick roof retaining wall was strictly maintained. Then, the mining area was evenly expanded to the designed mining width on both sides, precisely controlling the mining boundaries to minimize the mixing of surrounding rock and reduce ore dilution.

[0077] Standardized settings for rock drilling and blasting parameters: borehole diameter 38~42mm, borehole row spacing 0.8~1.0m, hole spacing 0.8~1.0m, with uniform and regular hole layout to ensure balanced blasting force. No. 2 rock explosive cartridges are used for blasting, with manual loading. Millisecond detonator micro-delay initiation technology is employed between rows, with the micro-delay initiation time controlled at 50 milliseconds to achieve uniform ore caving, ensuring moderately sized ore pieces, reducing the generation of large ore chunks and mixing with fractured surrounding rock, and improving the quality of mining.

[0078] 3.2 Ventilation operations in the mining area After a single blasting operation is completed, the ventilation system is turned on to fully ventilate and completely disperse harmful gases and dust from the work face. Once the ventilation test meets the standards, mechanized ore extraction operations are started.

[0079] 3.3 Mining operations Relying on the electric scraper equipment in the electric scraper chamber 4, the ore 5 that has collapsed in the mining area is evenly scraped and collected into the cutting level roadway 7 in the vein. Then, the shovel in the cutting level roadway loads the ore into the loading car and transports it to the transport roadway outside the vein, which can effectively avoid the safety hazards of manual mining.

[0080] 3.4 Roof Management and Support Operations After each round of blasting and ventilation, a thorough manual prying operation is first carried out to completely remove loose rocks from the roof and sides, eliminating surface safety hazards. Combining the structural advantages of this invention—a layered 1-2m roof retaining wall 15—and employing differentiated support techniques to control surrounding rock stability: In stable areas with good overall rock integrity and minimal fissures, conventional anchor bolt support is used; in areas with well-developed joints and fissures and moderate stability, a combination of anchor and mesh support is used; and in weak areas with broken rock and extremely poor stability, anchor spraying or concrete support is employed. The layered original roof retaining wall can isolate stress disturbances caused by settlement and deformation of the underlying filling material, ensuring the roof remains stable and fundamentally reducing the risk of roof falls and spalling.

[0081] 3.5 Mining Backfilling Operation After the single-layer ore is cleared, backfilling preparation work begins immediately. A sealed backfilling retaining wall 8 is constructed at the intersection of the corresponding layer end and the cutting level roadway to seal the stope void and prevent leakage of backfill slurry. The backfill slurry is transported into the stope through a dedicated backfilling borehole. This invention employs a layered, step-by-step differentiated proportioning backfilling process to adapt to the stress requirements of different areas, balancing safety and economy.

[0082] Specific backfilling operation process: Except for the uppermost layer of the ore body, all other layers are filled with 1:4 high-strength cemented backfill slurry to ensure the high strength bearing capacity of the bottom backfill body; when mining the uppermost layer of the ore body, the first step uses 1:4 high-strength cemented backfill to ensure the overall structural stability of the stope; the second step can use 1:16 low-strength backfill, tailings, or underground excavation waste rock for backfilling to achieve solid waste resource utilization. After each layer is filled, it is allowed to cure to the design strength before the next layer can be mined, and the entire intermediate section mining is completed in a cycle.

[0083] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A two-step upward inclined layered filling mining method with pre-reserved retaining wall, characterized in that, include: The mining block is divided into multiple inclined layers along the dip of the ore body, and further divided into first-stage stopes and second-stage pillars along the strike of the ore body. Construction preparation and cutting work; The first-stage stope is mined in layers from bottom to top. After each layer is mined, the original ore body is reserved on the top plate of the layer to protect the wall. After the single-layer mining is completed, the goaf is cemented and backfilled so that the cemented backfill body is connected to the retaining wall. After the first-step stope is fully mined and backfilled, the second-step pillar is mined using the same process, forming a two-step alternating mining cycle.

2. The two-step upward inclined layered filling mining method with reserved retaining wall as described in claim 1, characterized in that, The construction preparation and cutting process includes: The connecting roadway at both ends of the ore block was excavated to penetrate the ore body; The cutting tunnel is excavated along the footwall of the ore body, and at the center of the cutting tunnel, the cutting tunnel is then excavated upwards along the bottom plate of the ore body. Excavating the upper ventilation connecting roadway and the upper pedestrian ventilation roadway of the mining area; The ore extraction equipment is installed in an electric scraper chamber, which is at the same elevation as the cutting level roadway and is connected to the cutting level roadway.

3. The two-step upward inclined layered filling mining method with reserved retaining wall as described in claim 2, characterized in that, The stratified mining includes: Using the cutting uphill as the free face and compensation space, a retreating mining sequence from top to bottom is adopted. First, the top is pressed and trimmed to the layer boundary while retaining the roof wall, and then the side walls are expanded to the designed mining width.

4. The two-step upward inclined layered filling mining method with reserved retaining wall as described in claim 1, characterized in that, After the ore is extracted, differentiated support is adopted according to the stability of the surrounding rock. In stable areas, anchor bolt support is used, in moderately stable areas, anchor mesh combined support is used, and in broken and weak areas, anchor spraying or concrete support is used.

5. The two-step upward inclined layered filling mining method with reserved retaining wall as described in claim 1, characterized in that, Except for the top layer, the other layers are filled with high-strength cemented filling slurry; in the top layer, the first-stage stope is filled with high-strength cemented filling, and the second-stage pillar is filled with low-strength cemented filling, tailings or waste rock.

6. The two-step upward inclined layered filling mining method with reserved retaining wall as described in claim 2, characterized in that, The cemented filling includes: A filling retaining wall is constructed on the inner wall of the cutting tunnel near the goaf to seal off the goaf. Cemented backfilling is carried out in the upper pedestrian ventilation roadway into the goaf.

7. The two-step upward inclined layered filling mining method with reserved retaining wall as described in claim 6, characterized in that, After the mining of this layer is completed, the hanging wall haulage roadway is constructed in the next layer of ore body. The hanging wall haulage roadway is connected to the middle connecting roadway. Construct a filling retaining wall in the middle transport roadway to seal off the cutting level roadway and electric scraper chamber in the upper layer; Cemented filling is carried out on the cutting level tunnel and electric scraper chamber in the next layer.

8. The two-step upward inclined layered filling mining method with reserved retaining wall as described in claim 2, characterized in that, In the first-stage stope of the first-level stope, the center of the cutting uphill is used to carry out the expansion and mining operation. After the mining is completed, a high-strength backfill body is used for backfilling and maintenance. After the maintenance is completed, the second layer of the central area in the first-step ore stope is excavated, cut, and expanded for mining, while the backfilling operation is completed simultaneously. After the first-stage stope is fully mined and backfilled, the second-stage pillar is mined using the same process, advancing layer by layer upwards until the entire middle section of the ore body is mined out.

9. The two-step upward inclined layered filling mining method with reserved retaining wall as described in claim 1, characterized in that, The two-step alternating mining cycle is carried out alternately between each layer. When the lower layer is carrying out the first-step stope mining, the upper layer is simultaneously carrying out the second-step pillar mining operation, and the second-step pillar is used as the first mining site of the upper layer.

10. The two-step upward inclined layered filling mining method with reserved retaining wall as described in claim 1, characterized in that, Top pillars are left at the top of the mining area, while bottom pillars are eliminated during the mining process.

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