Solid potash mine backfilling mining method
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA MINMETALS CHANGSHA MINING RES INST
- Filing Date
- 2026-04-14
- Publication Date
- 2026-06-30
Smart Images
Figure CN122304746A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of mining engineering technology, and in particular relates to a method for backfilling mining of solid potash ore. Background Technology
[0002] Solid potash is an important strategic mineral resource for the country. Its ore bodies are usually hosted in weak evaporite strata, with low density and low mechanical strength, making them highly sensitive to the stability of the mining area. At present, potash mines at home and abroad still mainly use the traditional room and pillar method for mining. To ensure the safety of the mining area, this method usually requires leaving large-scale permanent pillars and thick roof and floor protective layers.
[0003] Existing technologies often adopt the design logic of hard rock mining, resulting in the inability of stope and support designs to match the special occurrence environment of potash mines, thus leading to increased construction costs and material waste. Summary of the Invention
[0004] In view of the technical problems existing in the background art, this application provides a solid potash ore backfilling mining method, including: Arrange the preparation work; Collect the rock mechanics parameters of the potash ore body and determine the mining method design based on these parameters; The rock mass mechanical parameters include the instantaneous compressive strength of the surrounding rock, the ore body integrity coefficient, and the allowable subsidence of the top and bottom plates; The mining method design includes mining sequence design, goaf filling design, and mining safety factor correction design.
[0005] In some embodiments, the process of collecting the rock mechanics parameters of the potash ore body and determining the mining method design based on these parameters includes: The instantaneous compressive strength of the surrounding rock of the potash ore body was collected, and the mining sequence was designed based on the instantaneous compressive strength of the surrounding rock. Collect ore body integrity coefficient parameters to determine the safety correction design for mining; The design for filling voids is based on long-term compressive strength and allowable settlement of the top and bottom slabs.
[0006] In some embodiments, the step of collecting the instantaneous compressive strength of the surrounding rock of the potash ore body and designing the mining sequence based on the instantaneous compressive strength of the surrounding rock includes: The instantaneous compressive strength of the surrounding rock is divided into at least three levels; The corresponding approach and mining interval is matched according to the different instantaneous compressive strength levels of the surrounding rock.
[0007] In some embodiments, the classification of the instantaneous compressive strength of the surrounding rock into at least three levels includes: The instantaneous compressive strength of the surrounding rock is divided into weak surrounding rock strength, medium-hard surrounding rock strength, and hard surrounding rock strength; The method of matching the corresponding access and mining interval according to different instantaneous compressive strength levels of surrounding rock includes: For the aforementioned weak surrounding rock strength, a three-mining-one-mining method is adopted for mining; For the medium-hardness surrounding rock, a two-mining-one-mining method is adopted for mining; For the aforementioned hard surrounding rock strength, a one-time-per-minute mining method is adopted for mining.
[0008] In some implementations, the process of collecting orebody integrity coefficient parameters to determine the safety correction design for mining includes: The ore body integrity coefficient parameter is divided into at least three levels; Based on different ore body integrity coefficient parameter levels, corresponding safety factor correction designs are matched.
[0009] In some embodiments, dividing the ore body integrity coefficient parameter into at least three levels includes: Based on the ore body integrity coefficient parameter, it is divided into three levels: complete, relatively complete, and broken. The design for matching corresponding safety factor corrections based on different ore body integrity coefficient parameter levels includes: For the complete ore body, routine mining site monitoring shall be performed; For the relatively intact ore body, roof support should be carried out immediately after mining, and the deformation of the surrounding rock should be monitored simultaneously. For the fractured ore body, a small-mining method is implemented.
[0010] In some embodiments, the method of implementing small-stope mining for the fractured ore body includes: The original mining area is designed to be divided into multiple sub-mining areas; the size of each sub-mining area is one-half to one-eighth of the original mining area. Before mining, the roof of the sub-mining area is pre-reinforced and supported; After mining, the surrounding rock in the empty area of the sub-mining site is reinforced before ore is extracted; High-strength cemented backfilling was carried out on the goaf.
[0011] In some embodiments, the design of void filling based on long-term compressive strength and allowable settlement of the top and bottom slabs includes: Based on the ore body occurrence conditions, the allowable roof subsidence is divided into at least three levels; The design for filling voids is based on the different allowable settlement requirements of the roof slab and the long-term compressive strength.
[0012] In some embodiments, classifying the allowable roof subsidence into at least three levels according to the ore body occurrence conditions includes: Based on the ore body occurrence conditions, the allowable subsidence of the roof is divided into three levels: strict, medium, and lenient. The design for filling voids based on different allowable settlement requirements of the roof slab, combined with long-term compressive strength, includes: To address the deformation risks and cost requirements at each level, a three-tiered differentiated filling method is adopted.
[0013] In some implementations, the three-tiered differentiated filling method, tailored to different levels of deformation risk and cost requirements, includes: For the aforementioned loose-grade goaf, self-compacting backfilling with mine tailings is adopted; For the medium-grade goaf, the goaf is divided into an upper layer and a lower layer along the height. The lower layer is filled with low-strength slurry or a mixture of low-strength slurry and waste rock, while the upper layer is filled with medium- and high-strength slurry to form a layered filling body. For the aforementioned strictly graded goaf, a gradual mining method is adopted, dividing the mining area into multiple mining sub-sections along the ore body strike. After the ore is extracted from each mining sub-section, retaining walls are immediately used to seal it, and early-strength slurry is used for filling. After the filling body has been cured to the design strength, the mining of the next sub-section is carried out.
[0014] This application proposes a safe and economical mining process design method for potash mines by independently assessing the safety of three main rock mass mechanical parameters and designing the corresponding steps separately based on the independent assessment results. This achieves a balance between mining efficiency and mining economy under the premise of safe mining. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the basic process of the solid potash ore backfilling mining method provided in the embodiments of this application; Figure 2 This is a schematic diagram of the mining process design for the solid potash backfilling mining method provided in the embodiments of this application; Figure 3 This is a schematic diagram of the mining sequence design of the solid potash backfill mining method provided in the embodiments of this application; Figure 4 This is a schematic diagram of the surrounding rock strength classification and access mining interval method of the solid potash mine backfilling mining method provided in the embodiments of this application; Figure 5 This is a schematic diagram of the ore body integrity coefficient classification and safety correction design process of the solid potash backfilling mining method provided in the embodiments of this application; Figure 6 This is a flowchart illustrating the safety control measures for ore body integrity grading in the solid potash backfilling mining method provided in the embodiments of this application; Figure 7 This is a schematic diagram of the process for mining a small stope in a crushed ore body using the solid potash backfilling mining method provided in the embodiments of this application. Figure 8 This is a schematic diagram of the design and classification of void filling in the solid potash mine filling method provided in the embodiments of this application; Figure 9 This is a schematic diagram of the roof subsidence level and differentiated backfill design of the solid potash mine backfilling mining method provided in the embodiments of this application; Figure 10 This is a schematic diagram illustrating the implementation of the three-stage differentiated backfilling process of the solid potash ore backfilling mining method provided in the embodiments of this application. Detailed Implementation
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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).
[0022] 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.
[0023] 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.
[0024] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0025] Reference Figure 1 A method for backfilling mining of solid potash ore, comprising: S101. Arrange the preparation work; Understandably, pre-mining engineering refers to the general term for the shaft and tunnel engineering constructed before the commencement of potash mining operations to build a complete operational system encompassing transportation, ventilation, backfilling, brine drainage, ore extraction, and personnel access. It is a prerequisite foundational engineering project for mining operations. This step requires consideration of the characteristics of potash mines, such as gentle dips, layered occurrence, easy water solubility, and relatively soft surrounding rock, to complete the positioning, specifications, and layout of supporting engineering works for the shafts and tunnels, ensuring that all systems are interconnected and fully functional.
[0026] Specifically, stage haulage roadways are arranged along the footwall of the potash ore body. These roadways have a rectangular cross-section of 6.0m to 8.0m wide and equal in width and height, serving as the main channels for ore transportation, equipment access, and ventilation. Perpendicular to the stage haulage roadways, through-vein haulage roadways are arranged every 40m to 60m, traversing the ore body and connecting to the stage haulage roadways to achieve zoned control of the ore blocks. From the through-vein haulage roadways, connecting roadways are excavated to each stope. The cross-sectional specifications of these connecting roadways are determined based on the external dimensions of the trackless ore extraction equipment. For example, these roadways typically have a rectangular cross-section of 6.0m to 8.0m wide and equal in width and height to ensure the passage needs of equipment and personnel. The project includes a backfilling return air shaft, a brine drain shaft, and an ore pass. The backfilling return air shaft is used for lowering backfilling pipelines and providing return air. The brine drain shaft is specifically designed to drain brine released during potash mining, preventing rock softening and stope instability caused by brine accumulation. The ore pass is used for centralized transport of ore after blasting. A 3-5m high bottom pillar is reserved at the bottom of the stope, eliminating the need for top pillars and intermediate pillars, thus reducing pillar loss and meeting the requirements of continuous potash mining.
[0027] S102. Collect the rock mechanics parameters of the potash ore body and determine the mining method design based on these parameters. The rock mechanics parameters include the instantaneous compressive strength of the surrounding rock, the integrity coefficient of the ore body, and the allowable subsidence of the roof and floor. The mining method design includes the mining sequence design, the goaf filling design, and the mining safety factor correction design.
[0028] Understandably, this step requires adapting potash mining technology by dividing the instantaneous compressive strength of the surrounding rock, the integrity coefficient of the ore body, and the allowable subsidence of the roof and floor into independent indicators, and designing construction methods based on these independent indicators. This is because in metal mining, the high hardness of the metal ore and the degree of fracture development reflect its compressive strength, and these three factors are often strongly correlated. However, the rock mass mechanical behavior of potash mines is dominated by the plastic creep, water solubility, and safety requirements of the aquitard, exhibiting a relatively independent state between integrity and compressive strength. For example, pure potash or halite ore bodies typically have extremely high integrity, and the short-term uniaxial compressive strength of the rock blocks can reach 20-30 MPa, comparable to medium-hardness sandstone. However, due to strong creep characteristics, its long-term strength is relatively lower than its short-term strength and will continue to decrease over time. Even if the ore body has no fractures, it will still undergo large deformations under long-term ground pressure, leading to pillar shrinkage and roadway closure, which is extremely rare in hard rock conditions.
[0029] For example, in potash ore bodies containing anhydrite interlayers, the short-term compressive strength of the rock blocks is higher than that of pure salt rock. However, due to the large difference in deformation modulus between anhydrite and salt rock, delamination and cracks often exist at the interface, exhibiting the characteristics of high compressive strength but poor integrity. In this case, the stability of the rock mass is actually worse, because the presence of interlayers will accelerate creep deformation and failure.
[0030] In potash mines, the allowable subsidence is mainly controlled by long-term creep strength rather than instantaneous rock mass strength. However, if only long-term creep strength is considered in the stope design, an overly conservative stope support system will be formed in the short-term mining, resulting in increased mining costs. Therefore, this scheme evaluates the three main rock mass mechanical parameters of potash mines independently and designs them separately, thereby improving economic benefits while meeting the conditions for safe mining.
[0031] In some implementations, refer to Figure 2 The process of collecting rock mechanics parameters of the potash ore body and determining the mining method design based on these parameters includes: S201. Collect the instantaneous compressive strength of the surrounding rock of the potash ore body, and design the mining sequence based on the instantaneous compressive strength of the surrounding rock; Understandably, the instantaneous compressive strength of the surrounding rock refers to its ultimate compressive strength under instantaneous load. It reflects the short-term bearing capacity of the roof in the initial stage of exposure and is a parameter that determines the single-time exposed area of the stope, the mining advance speed, and the mining interval between adjacent stops. The core of mining sequence design is to control the instantaneous exposure state of the stope roof to match its instantaneous bearing capacity with that of the surrounding rock, thereby preventing instantaneous roof collapse during mining operations.
[0032] S202. Collect ore body integrity coefficient parameters and determine the safety correction design for longwall mining; Understandably, in potash mining environments, the ore body integrity coefficient characterizes the degree of development of joints, fractures, and bedding within the potash ore body. It directly reflects the ore body's self-stabilizing ability, blasting fracturing effect, and brine seepage risk, thus characterizing the rate of deterioration of the stope's bearing capacity. Ore bodies with poor integrity are prone to spalling along bedding planes during mining. Therefore, the ore body integrity coefficient is the primary basis for determining support parameters, blasting parameters, and roof monitoring frequency during mining.
[0033] S203. Based on the long-term compressive strength and the allowable settlement of the top and bottom plates, design the filling of voids.
[0034] In potash mining environments, the long-term compressive strength of the surrounding rock specifically refers to its ultimate compressive strength under long-term constant ground pressure, characterizing its ability to resist long-term creep deformation. Potash mine surrounding rock exhibits significant creep characteristics, undergoing continuous plastic deformation under constant load. If the backfill cannot provide sufficient long-term support, large deformations will occur, leading to roof subsidence and floor heave. The allowable subsidence of the roof and floor is not only a key control indicator for stope safety in potash mines but also a core indicator for preventing brine leakage. When the roof and floor subsidence exceeds the allowable value, penetrating fissures will form between the surrounding rock and the backfill, becoming channels for brine leakage, causing groundwater pollution and stope instability. Therefore, it is necessary to combine the long-term compressive strength of the surrounding rock with the allowable subsidence of the roof and floor to determine the long-term strength of the backfill and the timing of backfilling, achieving long-term stability of the goaf and preventing brine leakage.
[0035] In some implementations, refer to Figure 3 S201. Collect the instantaneous compressive strength of the surrounding rock of the potash ore body, and design the mining sequence based on the instantaneous compressive strength of the surrounding rock, including: S301. The instantaneous compressive strength of the surrounding rock shall be divided into at least three levels; It is understandable that at least three levels can correspond to three stages of the surrounding rock in the stope being disturbed by the mining of adjacent stops: the stage where the surrounding rock in the stope deforms slightly and can be ignored under disturbance; the stage where the surrounding rock in the stope deforms under disturbance; and the stage where the roof of the stope is spalled and stripped.
[0036] Based on the above three stages, by determining three boundary values, we can determine the deformation state of the surrounding rock in which parts of the stope within the shortest mining cycle, thereby determining the approach and mining interval between stopes.
[0037] For example, the boundary value between the first and second levels corresponds to the critical strength at which the deformation of the surrounding rock under disturbance is negligible. When the instantaneous compressive strength of the surrounding rock is higher than this value, the blasting vibration and stress superposition generated by mining in adjacent stops will not cause observable plastic deformation of the surrounding rock in this stop, and will have no impact on the safety of mining in this stop. When the instantaneous compressive strength of the surrounding rock is lower than this value, the disturbance caused by mining in adjacent stops will cause irreversible plastic deformation of the surrounding rock in this stop. This boundary value is determined through field disturbance tests: blasting and mining operations in adjacent stops are simulated in the test stope, deformation data of surrounding rock with different strengths are measured, and the lowest instantaneous compressive strength of the surrounding rock corresponding to a deformation value of less than 1 mm is taken as the boundary value.
[0038] The boundary value between the second and third levels corresponds to the critical strength at which the surrounding rock will spall and detach when disturbed: when the compressive strength of the surrounding rock is higher than this value, even if plastic deformation occurs, it will only manifest as overall roof subsidence without local spalling or rock fragmentation; when the instantaneous compressive strength of the surrounding rock is lower than this value, disturbance during mining in adjacent stops will trigger the roof to spall and rock fragments to fall along the fracture surface, directly threatening the safety of workers. This boundary value is determined through field roof monitoring tests: in test stops with surrounding rock of different strengths, the roof damage during mining in adjacent stops is monitored, and the lowest instantaneous compressive strength of the surrounding rock corresponding to the absence of spalling is taken as the boundary value.
[0039] S302. Match the corresponding approach and mining interval method according to different instantaneous compressive strength levels of surrounding rock.
[0040] Understandably, the design goal of the approach and mining interval method is to control the disturbance impact on the surrounding rock of the mining area within the corresponding level of safety range by adjusting the mining time difference and spatial isolation between adjacent approaches.
[0041] In some implementations, refer to Figure 4 S301. The instantaneous compressive strength of the surrounding rock is divided into at least three levels, including: S401. The instantaneous compressive strength of the surrounding rock is divided into the strength of weak surrounding rock, the strength of medium-hard surrounding rock, and the strength of hard surrounding rock. It is understandable that in the potash mining environment, the three rock strength grades of weak, medium hard, and hard are used to correspond to at least three strength grades in the previous embodiment. In other embodiments, more grades can be divided according to different specific requirements.
[0042] Specifically, weak surrounding rock corresponds to a high-risk stage where the roof will spall and peel off; moderately hard surrounding rock corresponds to a medium-risk stage where observable deformation will occur when disturbed; and hard surrounding rock corresponds to a low-risk stage where disturbance and deformation are slight and negligible.
[0043] S302. Based on different instantaneous compressive strength levels of the surrounding rock, the corresponding approach and mining interval methods include: S402. For weak surrounding rock, a three-mining-one-mining method shall be adopted for mining. S403. For medium-hard surrounding rock, a two-mining-one-mining method is adopted for mining. S404. For hard surrounding rock, a one-time-per-minute mining method shall be adopted for mining.
[0044] Understandably, the main difference between the three mining interval methods is the number of isolation routes between adjacent mining routes. By adjusting the number of isolation routes, the influence range and intensity of stress superposition can be controlled, matching the disturbance resistance of the surrounding rock of the corresponding grade.
[0045] For example, in a potash mine, field tests determined that the critical strength for negligible deformation was 18 MPa, and the critical strength for spalling was 9 MPa. The instantaneous compressive strength of the surrounding rock in stope A was 22 MPa, classifying it as hard rock, and it was mined using an alternating-one-mining method. The instantaneous compressive strength of the surrounding rock in stope B was 14 MPa, classifying it as medium-hard rock, and it was mined using an alternating-two-mining method. The instantaneous compressive strength of the surrounding rock in stope C was 7 MPa, classifying it as weak rock, and it was mined using an alternating-three-mining method.
[0046] In some implementations, based on the strength design of the surrounding rock of the potash mine, the mining efficiency can be further improved by segmented synchronous mining.
[0047] In some implementations, refer to Figure 5 S202. Collect ore body integrity coefficient parameters and determine the safety correction design for longwall mining, including: S501. Divide the ore body integrity coefficient parameter into at least three levels; Understandably, in potash mining environments, the ore body integrity coefficient characterizes the degree of development of joints, fissures, and bedding within the ore body, as well as the degree of weakening due to brine contamination. It directly determines the ore body's self-stabilizing ability, blasting disturbance response, and risk of spalling and collapse. This implementation method divides the integrity coefficient into three levels, corresponding to three states: intact and stable ore body, relatively intact but easily disturbed ore body, and broken and easily unstable ore body.
[0048] S502. Based on different ore body integrity coefficient parameter levels, match the corresponding safety factor correction design.
[0049] Understandably, intact ore bodies are generally dense, with underdeveloped joints and fissures and weak brine contamination. When disturbed by blasting and mining, they only undergo elastic deformation, with no significant risk of rockfall or spalling. Relatively intact ore bodies have a few joints and weak surfaces, with slight local brine contamination. When disturbed, they will undergo slight plastic deformation, and local rockfall may occur. Fragmented ore bodies have dense joints and fissures, well-developed bedding, and severe brine softening. When disturbed, they are very prone to spalling, stripping, and caving, and have a short self-stabilization time. For the above three different occurrence states of the stopes, different support schemes need to be set up to meet the requirements of economic adaptability.
[0050] In some implementations, refer to Figure 6 The ore body integrity coefficient parameter is divided into at least three levels, including: S601. Based on the ore body integrity coefficient parameter, it is divided into three levels: complete, relatively complete, and broken. Based on different ore body integrity coefficient parameter levels, the corresponding safety factor correction design includes: S602. For intact ore bodies, conduct routine mining site monitoring. S603. For relatively intact ore bodies, roof support should be carried out immediately after mining, and surrounding rock deformation should be monitored simultaneously. S604. For fractured ore bodies, implement small-mining method.
[0051] Understandably, the ore body integrity coefficient, under potash mining conditions, characterizes the degree of development of joints, fractures, and bedding within the ore body, as well as the degree of weakening due to brine contamination. In other words, it characterizes the time it takes for the ore body to develop from instantaneous compressive strength to long-term compressive strength. The worse the ore body integrity, the faster its compressive strength deteriorates, and the faster it develops from instantaneous compressive strength to long-term compressive strength. Therefore, this implementation method, based on the ore body's own integrity status, adopts graded differentiated safety correction measures to match the safety control method with the degree of ore body fragmentation.
[0052] Specifically, based on the ore body integrity coefficient parameter, it is divided into three levels: complete, relatively complete, and broken. The rock and geology characteristics of each level of ore body have been described in the previous implementation method and will not be repeated here.
[0053] Understandably, for intact ore bodies, routine stope monitoring is sufficient. Intact ore bodies have strong self-stabilizing capabilities and minimal impact from mining disturbances. Only roof inspections, ventilation, and ore extraction monitoring are required according to standard mining requirements. There is no need for additional support reinforcement or stope reduction, and normal mining efficiency is maintained while ensuring safety.
[0054] For relatively intact ore bodies, roof support should be implemented immediately after mining, and surrounding rock deformation should be monitored simultaneously. Relatively intact ore bodies often have local weak points, which reduce roof stability after mining. Therefore, roof support must be implemented immediately after ore extraction to limit the expansion of surrounding rock deformation. Simultaneously, surrounding rock deformation monitoring should be conducted to monitor roof displacement in real time and prevent the expansion of local weak points from causing rockfalls.
[0055] For example, in a potash mine with a relatively intact ore body, after the ore is extracted in layers, rock bolts and metal mesh are immediately used for roof support, and a roof displacement monitoring instrument is used to continuously monitor the deformation of the surrounding rock to ensure the safety of the mining operation.
[0056] For fractured ore bodies, a small-stope mining method is implemented. Fractured ore bodies have extremely poor self-stabilization ability and high sensitivity to disturbance. By reducing the range of each mining operation and decreasing the exposed area and time of the roof, the impact of mining disturbance is reduced. This approach controls the risk of roof spalling and collapse, and protects the safety of the working space.
[0057] In some implementations, refer to Figure 7 S604. For fractured ore bodies, the small-stope mining method includes: S701. The original mining area is designed to be divided into multiple sub-mining areas; the size of the sub-mining area is one-half to one-eighth of the original mining area. Understandably, the size of the sub-mining is dynamically adjusted according to the degree of ore body fragmentation: the lower the integrity coefficient and the more severe the brine softening, the smaller the size of the sub-mining. By dividing the original mining area into multiple independent small units, block mining and backfilling are achieved, thereby avoiding collapses caused by large-area exposure of the roof.
[0058] S702. Before mining, the roof of the sub-mining area shall be pre-reinforced and supported. Understandably, the roof of the fractured ore body already has numerous primary fractures before mining, and its cohesion decreases significantly after being soaked in brine. Mining disturbances can easily trigger fracture propagation. Pre-reinforcement can anchor the roof rock mass in advance, improving its integrity and resistance to disturbance.
[0059] For example, a reinforced roadway is pre-excavated above the roof of the fractured ore body. In the reinforced roadway, a combination of anchor bolts, metal mesh, and anchor cables is used for pre-support. The anchor bolts are evenly distributed along the roof of the sub-mining, and the anchor cables are spaced out in the key bearing area of the roof. The support range extends 1m to 2m beyond the boundary of the sub-mining, forming an advanced support system.
[0060] S703. After mining, the surrounding rock in the goaf of the sub-mining area is reinforced before ore is extracted. Understandably, after blasting and excavating ore from a fractured ore body, the surrounding rock in the empty area will immediately become loose and deformed. If ore is extracted directly, the vibration of the extraction equipment will further exacerbate the instability of the surrounding rock, leading to spalling and collapse. Reinforcing the surrounding rock before extraction can stabilize the empty area's surrounding rock before extraction, ensuring the safety of the extraction operation.
[0061] For example, a combination of shotcrete, anchor bolts, and anchor mesh is used to reinforce the loose surrounding rock on both sides and the top of the empty area. After the shotcrete reaches its initial setting strength, a small scraper is used for ore extraction. During the ore extraction process, it is prohibited to excavate beyond the boundary of the empty area.
[0062] S704. High-strength cemented backfilling of the goaf.
[0063] Understandably, the surrounding rock of a fractured ore body exhibits significant long-term creep deformation, and brine easily seeps along fissures. Low-strength backfill cannot provide sufficient long-term support and is also insufficient to seal brine leakage channels. High-strength cemented backfill can form a stable artificial false roof and lateral support, controlling long-term deformation of the surrounding rock while simultaneously sealing brine leakage channels.
[0064] For example, graded tailings with a sand-to-cement ratio of 1:4 to 1:6 are used for backfilling. The strength of the backfill body is not less than 3MPa. The backfill height is consistent with the height of the sub-mining, and no open roof is left. After the backfill body is cured to more than 70% of the design strength, the mining operation of the adjacent sub-mining is carried out.
[0065] In some implementations, refer to Figure 8S203. Based on the long-term compressive strength and the allowable settlement of the top and bottom slabs, the design for filling the voids includes: S801. According to the ore body occurrence conditions, the allowable subsidence of the roof is divided into at least three levels; S802. Based on different allowable settlement requirements of the roof slab, and in combination with long-term compressive strength, design the void filling.
[0066] Understandably, in the environment of potash mining, the long-term compressive strength of the surrounding rock determines its long-term bearing capacity and creep deformation rate, while the allowable subsidence of the roof determines the critical deformation threshold for brine leakage. If only the long-term compressive strength is considered, brine leakage may occur even if the strength of the filling body is sufficient but the roof deformation exceeds the standard. If only the allowable subsidence of the roof is considered, overfilling may increase costs or insufficient strength of the filling body may lead to long-term instability of the surrounding rock.
[0067] In some implementations, refer to Figure 9 S801. Based on the ore body occurrence conditions, the allowable roof subsidence is divided into at least three levels, including: S901. According to the ore body occurrence conditions, the allowable roof subsidence is divided into three levels: strict, medium, and lenient. S802. Based on different allowable settlement requirements of the roof slab and combined with long-term compressive strength, the design of void filling includes: S902. To address the deformation risks and cost requirements at each level, a three-level differentiated filling method is adopted.
[0068] Understandably, this implementation method categorizes the risk level of permissible roof subsidence into three standardized levels: strict, moderate, and lenient. The strict level corresponds to scenarios with significant brine leakage risk and is applicable to areas with fractured surrounding rock, highly concentrated primary brine, proximity to surface drinking water bodies, underground aquifers, or important structures. At this level, even minor roof deformation can trigger penetrating fractures, and brine leakage would cause severe environmental pollution or safety accidents. Therefore, the control requirements for roof subsidence are relatively high, especially in mining areas where the long-term compressive strength of the roof is either poor or moderate.
[0069] Medium-level mining corresponds to the potential risk of brine leakage within the mining area. It is suitable for areas where the surrounding rock has a few primary fissures, local brine accumulation, and no significant water bodies or structures. In this area, the roof exceeding the specific type of variable will create a leakage channel. The leakage consequences are relatively controllable, and the control requirements for the amount of roof subsidence are moderate.
[0070] The lenient level corresponds to scenarios with no risk of brine leakage. It is suitable for mining areas with dense and intact surrounding rock, extremely low original brine content, and far away from water bodies and structures. In this area, roof deformation only affects the stability of the local surrounding rock structure and will not cause brine leakage. The control requirements for roof subsidence are relatively lenient, and the roof has poor or moderate long-term compressive strength.
[0071] Based on the above risk classification, the three-tiered differentiated backfilling method aims to address higher risks with higher backfilling strength, earlier backfilling timing, and more comprehensive seepage prevention measures. It is also dynamically adjusted based on the long-term compressive strength of the surrounding rock. For example, in strictly controlled mining areas with strong long-term roof compressive strength, a medium-level backfilling method combined with additional reinforcement measures can be used instead of strict backfilling. Additional reinforcement measures can include combined anchor-mesh-shotcrete reinforcement, anchor cable reinforcement, or grouting reinforcement.
[0072] In some implementations, refer to Figure 10 S902. To address the deformation risks and cost requirements at each level, a three-tiered differentiated filling method is adopted, including: S1001. For loose-grade goaf areas, self-compacting backfilling with mine tailings shall be adopted; S1002. For medium-grade goaf areas, the goaf area is divided into an upper layer and a lower layer along the height. The lower layer is filled with low-strength slurry or a mixture of low-strength slurry and waste rock, while the upper layer is filled with medium- and high-strength slurry to form a layered filling body. S1003. For strictly graded goaf areas, a gradual mining method is adopted, dividing the mining area into multiple mining sub-sections along the ore body strike. After the ore is extracted from each mining sub-section, a retaining wall is immediately used to seal it, and early-strength slurry is used for filling. After the filling body has been cured to the design strength, the mining of the next sub-section is carried out.
[0073] It is understandable that this implementation method has constructed a differentiated backfilling process system for different roof subsidence risk levels of potash mines, thereby balancing the economy and safety of the backfilling method.
[0074] Understandably, tailings from mines are the main solid waste generated during potash ore beneficiation. They have a good particle size distribution and are characterized by high natural density and low permeability. In loose-grade goaf areas, there is no risk of brine leakage; only basic surrounding rock support requirements need to be met. Using self-compacting tailings backfill can provide sufficient lateral support through the tailings' own density, while simultaneously addressing the environmental issues associated with tailings storage.
[0075] Based on this, adjustments are made according to the long-term compressive strength of the surrounding rock. When the long-term compressive strength of the surrounding rock is high, the support requirements can be met by directly using pure tailings self-compacting filling. When the long-term compressive strength of the surrounding rock is low, a thin layer of low-strength cementing section can be added to the top of the tailings filling body to improve the overall support effect and adapt to the working conditions where the long-term bearing capacity of the surrounding rock is weak.
[0076] For medium-grade goaf areas, the goaf is divided into upper and lower layers along its height. The lower layer is filled with low-strength grout or a mixture of low-strength grout and waste rock, while the upper layer is filled with medium- to high-strength grout, forming a layered backfill. It is understandable that medium-grade goaf areas pose a potential risk of brine leakage, requiring simultaneous control of roof deformation and backfilling costs. The lower layer primarily serves to fill the goaf's volume and has lower strength requirements; the upper layer, in direct contact with the roof, needs to provide sufficient support to limit roof deformation and also acts as a seepage barrier. Through layered backfilling, the amount of cementitious material used can be reduced while ensuring effective roof deformation control, thus lowering backfilling costs.
[0077] When the long-term compressive strength of the surrounding rock is high, the amount of binder in the upper medium-high strength grout can be appropriately reduced, and the thickness of the upper layer can be reduced. When the long-term compressive strength of the surrounding rock is low, the strength of the upper grout and the thickness of the upper layer should be increased accordingly. The higher strength filling body can be used to compensate for the insufficient long-term bearing capacity of the surrounding rock and control the settlement of the roof within the allowable range.
[0078] For example, the goaf is divided into a lower layer and an upper layer along the height in a ratio of 2:1; the lower layer is filled with a low-strength cementitious slurry with a lime-sand ratio of 1:12 to 1:15, or a low-strength slurry mixed with underground excavated waste rock in a ratio of 1:1; the upper layer is filled with a medium-high strength cementitious slurry with a lime-sand ratio of 1:6 to 1:8, and the thickness of the upper layer is not less than 2m to ensure close contact with the roof and seal potential micro-cracks.
[0079] Specifically, for severely graded goaf areas, a gradual mining approach is adopted. The stope is divided into multiple mining sub-sections along the ore body strike. After ore extraction from each sub-section is completed, retaining walls are immediately used to seal it, and early-strength grout is used for backfilling. Once the backfill reaches the designed strength, mining of the next sub-section begins. It is understandable that severely graded goaf areas pose a significant risk of brine leakage, necessitating strict control of the exposed roof area and exposure time to prevent the formation of penetrating fractures. The gradual mining and immediate backfilling method divides the large stope into multiple independent small units, with each sub-section being sealed and backfilled immediately after mining, ensuring the roof remains under control at all times.
[0080] When the long-term compressive strength of the surrounding rock is high, the length of the mining sub-section can be appropriately increased, and the design strength of the early-strength grout can be moderately reduced. When the long-term compressive strength of the surrounding rock is low, the length of the mining sub-section can be reduced, the proportion of early-strength grout binder can be increased, or additional support structures can be added to shorten the curing time for the filling body to reach the design strength, provide effective support for the weak surrounding rock, control roof deformation, and reduce the risk of brine leakage.
[0081] For example, the mining area is divided into mining sections with a length of 5m to 8m along the ore body strike; after the ore is extracted from each section, a concrete retaining wall is built at the end of the section, with a thickness of not less than 0.5m; after the retaining wall reaches its initial setting strength, it is immediately filled with an early-strength cementitious grout with a cement-sand ratio of 1:4 to 1:6, and the 3-day strength of the filling body is not less than 2MPa; mining operations can only be carried out on the next adjacent section after the filling body has cured to more than 70% of its design strength.
[0082] In some embodiments, after collecting the rock mechanics parameters of the potash ore body and determining the mining method design based on these parameters, the solid potash ore backfilling mining method provided in this application further includes: The method of upward horizontal layered filling was adopted for layer-by-layer mining.
[0083] Understandably, this application improves stope safety by conducting independent parameter evaluations and progressive optimizations, ensuring stability during stope mining through mining sequence design, ensuring overall stability of the ore body after filling through goaf filling design, and addressing the creep effect unique to solid potash ore through mining safety factor correction design. This allows for improved recovery of solid potash ore through upward horizontal layered filling method. Compared to the room-and-pillar method, this implementation method eliminates the need for pillars by conducting independent evaluations of multiple parameters and optimizing safety design layer by layer, thus avoiding the low recovery rate of solid potash ore caused by conventional room-and-pillar method where 8m is mined and 10m is left.
[0084] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in this application, and within the spirit and principles of this application, should be included within the scope of protection of this application.
[0085] 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 method for backfilling mining of solid potash ore, characterized in that, include: Arrange the preparation work; Collect the rock mechanics parameters of the potash ore body and determine the mining method design based on these parameters; The rock mass mechanical parameters include the instantaneous compressive strength of the surrounding rock, the ore body integrity coefficient, and the allowable subsidence of the top and bottom plates; The mining method design includes mining sequence design, goaf filling design, and mining safety factor correction design.
2. The solid potash ore backfilling mining method according to claim 1, characterized in that, The process of collecting the rock mechanics parameters of the potash ore body and determining the mining method design based on these parameters includes: The instantaneous compressive strength of the surrounding rock of the potash ore body was collected, and the mining sequence was designed based on the instantaneous compressive strength of the surrounding rock. Collect ore body integrity coefficient parameters to determine the safety correction design for mining; The design for filling voids is based on long-term compressive strength and allowable settlement of the top and bottom slabs.
3. The solid potash ore backfilling mining method according to claim 2, characterized in that, The process of collecting the instantaneous compressive strength of the surrounding rock of the potash ore body and designing the mining sequence based on the instantaneous compressive strength of the surrounding rock includes: The instantaneous compressive strength of the surrounding rock is divided into at least three levels; The corresponding approach and mining interval is matched according to the different instantaneous compressive strength levels of the surrounding rock.
4. The solid potash ore backfilling mining method according to claim 3, characterized in that, The instantaneous compressive strength of the surrounding rock is divided into at least three levels, including: The instantaneous compressive strength of the surrounding rock is divided into weak surrounding rock strength, medium-hard surrounding rock strength, and hard surrounding rock strength; The method of matching the corresponding access and mining interval according to different instantaneous compressive strength levels of surrounding rock includes: For the aforementioned weak surrounding rock strength, a three-mining-one-mining method is adopted for mining; For the medium-hardness surrounding rock, a two-mining-one-mining method is adopted for mining; For the aforementioned hard surrounding rock strength, a one-time-per-minute mining method is adopted for mining.
5. The solid potash ore backfilling mining method according to claim 2, characterized in that, The determination of the safety correction design for longwall mining, based on the collected ore body integrity coefficient parameters, includes: The ore body integrity coefficient parameter is divided into at least three levels; Based on different ore body integrity coefficient parameter levels, corresponding safety factor correction designs are matched.
6. The solid potash ore backfilling mining method according to claim 5, characterized in that, The method of classifying the ore body integrity coefficient parameter into at least three levels includes: Based on the ore body integrity coefficient parameter, it is divided into three levels: complete, relatively complete, and broken. The design for matching corresponding safety factor corrections based on different ore body integrity coefficient parameter levels includes: For the complete ore body, routine mining site monitoring shall be performed; For the relatively intact ore body, roof support should be carried out immediately after mining, and the deformation of the surrounding rock should be monitored simultaneously. For the fractured ore body, a small-mining method is implemented.
7. The solid potash ore backfilling mining method according to claim 6, characterized in that, The method of implementing small-mining recovery for the fractured ore body includes: The original mining area is designed to be divided into multiple sub-mining areas; the size of each sub-mining area is one-half to one-eighth of the original mining area. Before mining, the roof of the sub-mining area is pre-reinforced and supported; After mining, the surrounding rock in the empty area of the sub-mining site is reinforced before ore is extracted; High-strength cemented backfilling was carried out on the goaf.
8. The solid potash ore backfilling mining method according to claim 2, characterized in that, The design for filling voids based on long-term compressive strength and allowable settlement of the top and bottom slabs includes: Based on the ore body occurrence conditions, the allowable roof subsidence is divided into at least three levels; The design for filling voids is based on the different allowable settlement requirements of the roof slab and the long-term compressive strength.
9. The solid potash ore backfilling mining method according to claim 8, characterized in that, The method of classifying the allowable subsidence of the roof into at least three levels according to the ore body occurrence conditions includes: Based on the ore body occurrence conditions, the allowable subsidence of the roof is divided into three levels: strict, medium, and lenient. The design for filling voids based on different allowable settlement requirements of the roof slab, combined with long-term compressive strength, includes: To address the deformation risks and cost requirements at each level, a three-tiered differentiated filling method is adopted.
10. The solid potash ore backfilling mining method according to claim 9, characterized in that, The three-tiered differentiated filling method, tailored to the deformation risk and cost requirements at each level, includes: For the aforementioned loose-grade goaf, self-compacting backfilling with mine tailings is adopted; For the medium-grade goaf, the goaf is divided into an upper layer and a lower layer along the height. The lower layer is filled with low-strength slurry or a mixture of low-strength slurry and waste rock, while the upper layer is filled with medium- and high-strength slurry to form a layered filling body. For the aforementioned strictly graded goaf, a gradual mining method is adopted, dividing the mining area into multiple mining sub-sections along the ore body strike. After the ore is extracted from each mining sub-section, retaining walls are immediately used to seal it, and early-strength slurry is used for filling. After the filling body has been cured to the design strength, the mining of the next sub-section is carried out.