Secondary groove expanding blasting method for cutting groove of steeply inclined broken thin ore body

Abstract

The invention provides a steeply inclined broken thin ore body cutting groove secondary groove expanding blasting method, and belongs to the technical field of metal mine mining, and the method comprises the following steps: S1, blast hole arrangement design and construction: a plurality of rows of groove expanding blast holes are arranged on a goaf side wall formed by first cutting groove blasting along the ore body trend, and the blast holes comprise upward vertical holes and fan-shaped medium-length holes; s2, stage blasting design is conducted, specifically, the multiple rows of groove expanding blast holes are divided into two blasting stages for sequential blasting, in the first stage, at least one row of blast holes closest to the goaf are firstly blasted to conduct preliminary groove expanding, and in the second stage, all follow-up blast holes are blasted at a time through an expanded free face formed through blasting in the first stage; and S3, designing a charging and detonating network, wherein the detonating network adopts an electronic detonator detonating system to implement millisecond-level differential control. The mode that the upward vertical holes and the fan-shaped holes are combined is adopted, the capacity expansion efficiency is guaranteed, excessive disturbance of blasting to surrounding rock is avoided, and the roof caving risk is reduced.

Description

Technical Field

[0001] This application belongs to the technical field of metal mining, and more specifically, it relates to a method for secondary expansion blasting of cutting grooves in steeply inclined, fractured, thin ore bodies. Background Technology

[0002] In underground metal mining, segmented deep-hole blasting continuous mining is widely used for steeply inclined, fractured, and thin ore bodies due to its high efficiency and safety. The key to this method is forming an initial cutting groove, providing the necessary free face and compensation space for subsequent large-scale blasting. However, the volume of the cutting groove formed in the initial blast is often limited. When the volume of the cutting groove is less than 30% of the ore volume dropped by subsequent blasts, insufficient compensation space leads to high ore blasting clamping forces, resulting in problems such as a high rate of large blocks, increased explosive consumption per unit volume, and poor ore throwing, seriously affecting mining efficiency and safety.

[0003] Existing technologies typically employ methods such as increasing the scale of a single blast or increasing the density of boreholes to widen the trench. However, these methods have significant drawbacks: a single large-charge blast can easily lead to over-crushing of the ore, instability of the surrounding rock, or even roof collapse accidents; while simply increasing the number of boreholes significantly increases drilling costs and operating time, resulting in poor economic efficiency. Summary of the Invention

[0004] The purpose of this application is to provide a secondary blasting method for cutting grooves in steeply inclined, fractured, thin ore bodies, in order to solve the technical problem that the existing methods of increasing the scale of a single blast or increasing the density of blast holes for groove expansion have obvious defects.

[0005] To achieve the above objectives, the technical solution adopted in this application is: to provide a method for secondary widening blasting of a cutting groove in a steeply inclined, fractured, thin ore body, comprising the following steps: S1. Design and construction of borehole layout: On the side wall of the empty area formed by the first cutting slot blasting, multiple rows of widening blast holes are arranged along the ore body strike. The blast holes include upward vertical holes and fan-shaped medium-deep holes. S2, Stage blasting design: The multi-row blasting holes are divided into two blasting stages for sequential blasting. In the first stage, at least one row of blasting holes closest to the empty area is blasted to perform preliminary blasting. In the second stage, the enlarged free surface formed by the blasting in the first stage is used to blast all subsequent blasting holes in one go. S3. Charge and initiation network design: Bulk explosives are used in conjunction with detonating cords and electronic detonators for continuous charging, and a decoupled charge structure is used for the borehole openings of adjacent roadways to protect the roadway brow line; the initiation network uses an electronic detonator initiation system to implement millisecond-level micro-delay control, realizing sequential initiation of boreholes between two blasting stages and within each stage. In combination with the above technical solutions, in one possible implementation, in S1, the row spacing of the multi-row expanded slot boreholes is 0.8m to 1.6m, the hole spacing is 0.8m to 1.6m, the hole diameter is 65mm to 80mm, and the bottom distance of the deep holes in the fan shape is 1.0m to 1.5m.

[0006] In one possible implementation, based on the above technical solutions, in S2, the target of the first stage blasting is the first row of blast holes closest to the empty area, and the target of the second stage blasting is the blast holes that are cut from the 2nd to the 6th row.

[0007] In combination with the above technical solutions, in one possible implementation, in S2, all the first row of blast holes are arranged in a combination of upward vertical holes and fan-shaped holes; and in the blast holes of the second stage blasting, the last row of blast holes located on the easternmost side is also arranged in a combination of upward vertical holes and fan-shaped holes.

[0008] In combination with the above technical solutions, in one possible implementation, in S3, the method of the decoupled charge structure is as follows: fill the bulk explosive to a distance of 2.0m to 2.5m from the orifice, fill in 0.6m to 0.8m of stemming material as a partition layer, then fill in 2 to 3 rolls of small-diameter explosive cartridges, and finally seal the orifice with 0.5m to 0.8m of stemming material.

[0009] In combination with the above technical solutions, in one possible implementation, in S3, in the design of the detonation network for the second stage of blasting, a delay jump of no less than 300ms is set between the upward vertical holes and the combined blast holes in the same row, to ensure that all vertical holes in the row are detonated and form a new free surface before the combined blast holes in the same row are detonated.

[0010] In one possible implementation, based on the above technical solutions, in S3, the bulk explosive is expanded ammonium nitrate explosive, which is loaded using a charging device; the detonating charge is a rolled emulsion explosive, which is placed at the bottom of the hole along with 2 to 3 electronic detonators; and a detonating cord is laid along the entire length of the borehole.

[0011] In combination with the above technical solutions, in one possible implementation, in S3, the millisecond-level differential control is as follows: in the first stage, the internal blast holes are detonated sequentially in segments with a delay of 25ms to 175ms; in the second stage, the upward vertical holes in different rows are detonated sequentially with a delay of 25ms to 150ms.

[0012] In one possible implementation, in conjunction with the above technical solutions, before S1, a step of grouting pre-reinforcement of the fractured ore body is included.

[0013] In one possible implementation, based on the above technical solutions, the secondary expansion blasting method for cutting grooves in steeply inclined fractured thin ore bodies is applicable to the segmented deep-hole blasting continuous mining method for steeply inclined fractured thin ore bodies.

[0014] The beneficial effects of the secondary blasting method for widening the cutting groove in a steeply inclined, fractured, thin ore body provided in this application are as follows: Compared with the prior art, this application systematically solves a series of problems caused by insufficient space in the primary cutting groove of a fractured ore body through a two-stage blasting mode of preliminary groove widening and subsequent follow-up blasting, combined with a specific combination of blast holes and charge structure. In the two-stage blasting mode of this method, the first stage blasts at least one row of blast holes closest to the empty area to perform preliminary groove widening, creating better conditions for subsequent blasting; the second stage utilizes the widened free surface formed in the first stage to blast all subsequent blast holes in one go, effectively expanding the volume of the cutting groove, thereby greatly reducing the blasting clamping force and significantly improving the ore-falling effect. The combination of upward vertical holes and fan-shaped holes ensures both expansion efficiency and avoids excessive disturbance to the surrounding rock during blasting, reducing the risk of roof collapse.

[0015] In underground metal mining, sufficient compensation space is crucial for the successful blasting and throwing of ore. This method, through a rational arrangement of blast holes and a staged blasting design, ensures that the volume of the cutting groove can meet the needs of subsequent blasting ore volume. This allows the ore to be blasted in a relatively relaxed environment, reducing the risk of over-crushing of the ore and instability of the surrounding rock, and ensuring the safe operation of subsequent large-scale continuous mining. At the same time, ample compensation space also helps to improve the throwing effect of ore, reduce ore accumulation in the blasting area, and improve mining efficiency. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A plan view of the borehole layout for a secondary expansion blasting method for cutting a steeply inclined, fractured, thin ore body, provided in an embodiment of this application; Figure 2 A three-dimensional schematic diagram of the secondary expansion blast hole for a secondary expansion blasting method for cutting grooves in a steeply inclined, fractured, thin ore body, provided in an embodiment of this application; Figure 3 A diagram showing the arrangement of two rows of blast holes for a secondary expansion blasting method for cutting a steeply inclined, fractured thin ore body, provided in an embodiment of this application. Figure 4A diagram showing the arrangement of blast holes in rows 1-2 of a secondary blasting method for cutting a steeply inclined, fractured, thin ore body, provided in an embodiment of this application. Figure 5 This is a structural schematic diagram of a secondary blasting method for cutting grooves in steeply inclined, fractured, thin ore bodies, provided in an embodiment of this application. Figure 6 Design diagram of blasting network segments of cut 2 to cut 6 rows for a secondary expansion blasting method for cutting grooves of steeply inclined fractured thin ore body provided in the embodiments of this application; Figure 7 This is a schematic diagram of the connection of the cutting 2 to cutting 6 rows of blasting network in a secondary expansion blasting method for cutting grooves of a steeply inclined, fractured, thin ore body, provided in an embodiment of this application. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the described embodiments are only a part of the embodiments of this application, not all of them. The specific embodiments described herein are only used to explain this application and are not intended to limit this application. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] It should be further noted that the accompanying drawings and embodiments of this application mainly describe the concept of this application. Based on this concept, some specific forms and arrangements such as positional relationships may not be fully described. However, given that those skilled in the art understand the concept of this application, they can implement the above-mentioned specific forms and arrangements in a well-known manner.

[0020] The present application provides a method for secondary expansion blasting of a cutting groove in a steeply inclined, fractured, thin ore body.

[0021] like Figures 1 to 7 As shown, one embodiment of this application provides a method for secondary widening blasting of a cutting groove in a steeply inclined, fractured, thin ore body, comprising the following steps: S1. Design and Construction of Blasting Holes: On the sidewall of the empty area formed by the first cutting trench blast, six rows of widening blast holes are arranged along the strike of the ore body, from row 1 to row 6. Row 1 has 5 blasting positions, rows 2 to 4 each have 5 blasting positions, and rows 5 and 6 each have 4 blasting positions. The blast holes include upward vertical holes and fan-shaped medium-deep holes. Vertical holes are drilled at positions O11 to O15, and fan-shaped holes are arranged to the south (rows 1-1 to 1-5). Vertical holes are mainly drilled at positions O21 to O64. Among them, specific positions located on the easternmost side (such as O25, O35, O45, O54, and O64) need to drill upward vertical holes and also need to drill fan-shaped deep holes to the east to control the eastern boundary and provide better throwing conditions for the second stage of blasting.

[0022] S2. Stage blasting design: The six rows of blasting holes are divided into two blasting stages for sequential blasting. In the first stage, the first row of blasting holes closest to the empty area is blasted to perform preliminary blasting. In the second stage, the enlarged free surface formed by the blasting in the first stage is used to blast the subsequent rows of blasting holes from the second to the sixth row in one go.

[0023] S3. Charge and initiation network design: Bulk explosives are used in conjunction with detonating cords and electronic detonators for continuous charging, and a decoupled charge structure is used for the borehole openings of adjacent roadways to protect the roadway brow line; the initiation network uses an electronic detonator initiation system to implement millisecond-level micro-delay control, realizing sequential initiation of boreholes between two blasting stages and within each stage.

[0024] This embodiment provides a secondary blasting method for widening the cutting groove in a steeply inclined, fractured, thin ore body. Compared with existing technologies, this method systematically solves a series of problems caused by insufficient space in the primary cutting groove of a fractured ore body through a two-stage blasting mode of initial groove widening and subsequent follow-up blasting, combined with a specific combination of blast holes and charge structure. The two-stage blasting mode of this method involves: first, blasting at least one row of blast holes closest to the empty area for initial groove widening, creating better conditions for subsequent blasting; second, utilizing the widened free surface formed in the first stage, blasting all subsequent blast holes in one go, effectively expanding the volume of the cutting groove, thereby greatly reducing the blasting clamping force and significantly improving the ore extraction effect. The combination of upward vertical holes and fan-shaped holes ensures both expansion efficiency and avoids excessive disturbance to the surrounding rock, reducing the risk of roof collapse.

[0025] In underground metal mining, sufficient compensation space is crucial for the successful blasting and throwing of ore. This method, through a rational arrangement of blast holes and a staged blasting design, ensures that the volume of the cutting groove can meet the needs of subsequent blasting ore volume. This allows the ore to be blasted in a relatively relaxed environment, reducing the risk of over-crushing of the ore and instability of the surrounding rock, and ensuring the safe operation of subsequent large-scale continuous mining. At the same time, ample compensation space also helps to improve the throwing effect of ore, reduce ore accumulation in the blasting area, and improve mining efficiency.

[0026] like Figures 1 to 3 As shown, this application provides another specific implementation method based on the above-described implementation method as follows: In S1, the row spacing of the multi-row expanded slot blast holes is 0.8m to 1.6m, the hole spacing is 0.8m to 1.6m, the hole diameter is 65mm to 80mm, and the bottom distance of the deep holes in the fan shape is 1.0m to 1.5m. The machine positions O11 to O15 of the first row are arranged with upward vertical holes and southward fan-shaped holes, forming a fan-shaped hole bundle of rows 1-1 to 1-5.

[0027] The parameters were designed with precise calculations. The values ​​of row spacing and hole spacing not only avoid the cost surge and extended operation cycle caused by simply increasing the density of blast holes, but also overcome the problem of uneven distribution of blasting energy caused by excessive hole spacing. This ensures that the blasting energy of adjacent blast holes is effectively superimposed, achieving continuous crushing of the ore body and reducing energy waste.

[0028] A borehole diameter of 65mm to 80mm is suitable for the loading efficiency and blasting power of bulk explosives, avoiding explosive agglomeration or energy dispersion. A fan-shaped medium-deep borehole with a bottom distance of 1.0m to 1.5m precisely eliminates blasting blind zones, ensures uniform crushing in the thickness direction of the ore body, and reduces the generation of large ore chunks.

[0029] The combination of vertical holes and southward fan-shaped holes in the first row forms a fan-shaped hole bundle. This bundle not only leverages the high precision of the vertical holes to quickly construct the initial expansion channel, but also expands the initial expansion range through the divergent arrangement of the fan-shaped holes, creating sufficient compensation space for subsequent blasting. At the same time, it conforms to the strike characteristics of the steeply dipping ore body, ensuring that the cutting groove expands uniformly along the extension direction of the ore body, laying the foundation for large-scale continuous mining.

[0030] like Figures 1 to 4 As shown, this application provides another specific implementation method based on the above-described implementation method as follows: In S2, the first stage blasting utilizes the initial cut groove void as the initial free surface, and the second stage blasting utilizes the new free surface formed by the first stage blasting.

[0031] The first stage uses the empty area of ​​the initial cut groove as the initial free surface, which can quickly overcome the volume limitation of the initial cut groove and achieve preliminary groove expansion through precise blasting, effectively releasing the internal stress of the ore body and reducing the clamping force of subsequent blasting. The second stage uses the new free surface formed in the first stage, which provides a smoother release channel for blasting energy and avoids the problems of energy waste and poor blasting effect caused by insufficient free surface in traditional single blasting.

[0032] The progressive expansion of the free face allows each stage of blasting to be carried out under optimal operating conditions. This ensures the steady expansion of the cutting groove volume to meet the compensation space requirements of subsequent large-scale blasting, while reducing the disturbance of the blast shock wave to the surrounding rock, lowering the risk of roof collapse and spalling in steeply inclined, fractured thin ore bodies, and improving the smoothness of ore throwing, thus facilitating subsequent loading operations.

[0033] like Figures 1 to 4 As shown, this application provides another specific implementation method based on the above-described implementation method as follows: In S2, the first row of blast holes is arranged in a combination of upward vertical holes and fan-shaped holes; and in the second stage of blasting, the last row of blast holes on the easternmost side is also arranged in a combination of upward vertical holes and fan-shaped holes.

[0034] The arrangement of the first row of blast holes combines the advantages of easy construction and precise positioning of upward vertical holes with the wide expansion range of fan-shaped holes. This allows for the rapid formation of a regular and sufficiently large initial expansion free surface during the first stage of blasting, providing a good foundation for the second stage of blasting and effectively solving the core problem of insufficient space in the initial cutting groove.

[0035] The second stage uses the same combination of blast holes in the final row, focusing on boundary control. By utilizing the directional blasting characteristics of the fan-shaped holes, the propagation range of blasting energy is precisely constrained, preventing excessive energy diffusion to the surrounding rock on the east side and protecting the stability of the surrounding rock.

[0036] For steeply inclined, fractured, thin ore bodies, the combination design of blast holes not only ensures the expansion efficiency inside the cutting groove, but also achieves precise control of the blasting boundary, reducing ore over-crushing and resource waste, while also reducing the risk of surrounding rock instability, ensuring the safety and efficiency of mining operations, and making the shape of the cutting groove more suitable for the subsequent continuous mining operations.

[0037] like Figures 1 to 3 As shown, this application provides another specific implementation method based on the above-described implementation method as follows: In S3, the method for decoupled charge structure is as follows: fill the bulk explosive to a distance of 2.0m to 2.5m from the orifice, fill in 0.6m to 0.8m of stemming material as a partition layer, then fill in 2 to 3 rolls of small diameter explosive cartridges, and finally seal the orifice with 0.5m to 0.8m of stemming material.

[0038] First, the depth of the bulk explosive charge ensures the detonation center is far from the borehole opening, reducing the direct impact of the shock wave on the tunnel ridgeline. Second, the stemming layer absorbs some of the blast energy, preventing the high-temperature, high-pressure explosive gases from directly impacting the borehole opening, further attenuating the shock wave intensity. Finally, the stemming sealing at the borehole opening ensures a tight seal for the explosive gases and further buffers residual energy, significantly reducing the risk of tunnel ridgeline collapse and surrounding rock fissure expansion, extending the tunnel's service life, and reducing maintenance costs.

[0039] In terms of energy utilization, this structure achieves precise distribution of explosive energy. The bulk explosive in the middle and lower part ensures thorough crushing of the deep ore body, and the small diameter explosive cartridge at the orifice avoids over-crushing of the ore due to excessive explosive charge, making the ore crushing particle size more uniform and increasing the proportion of qualified blocks. At the same time, it avoids energy waste caused by the leakage of explosive gas, improves the utilization rate of explosives, reduces the unit consumption of explosives, and is suitable for the dual requirements of roadway stability and blasting quality for steeply inclined crushed thin ore bodies.

[0040] like Figures 5 to 7 As shown, this application provides another specific implementation method based on the above-described implementation method as follows: In S3, in the design of the detonation network for the second stage of blasting, a delay jump of no less than 300ms is set between the upward vertical holes and the combined blast holes in the same row to ensure that all vertical holes in the row are detonated and form a new free surface before the combined blast holes in the same row are detonated.

[0041] The blasting sequence for the first stage is set as follows: 25ms for holes 1-1-2 and 1-2-3, 50ms for holes 1-1-3, 1-2-4 and 1-3-3, 75ms for holes 1-1-4, 1-2-5 and 1-3-4, 100ms for holes 1-1-5, 1-2-6 and 1-3-5, 125ms for holes 1-1-6 and 1-3-6, 150ms for holes 1-4-1 to 1-4-4, and 175ms for holes 1-5-1 to 1-5-4.

[0042] The detonation sequence for the second stage of blasting is as follows: first, the vertical holes cutting rows 2 to 6 are detonated sequentially from south to north with delays of 25ms, 50ms, 75ms, 100ms, and 150ms; then, the combined holes on the east side are detonated with delays from west to east. A 300ms delay jump segment is set between the vertical holes and the combined blast holes.

[0043] A two-stage blasting method was adopted: the first row of holes was blasted as a pilot blast, followed by subsequent rows of holes blasted sequentially. The delay between rows was 25ms to 50ms, and a 300ms interval was set between vertical holes and combined blast holes. The detonation point was far from the working face, achieving safe and efficient expansion. The 300ms delay interval provided sufficient time for the stable formation of the free surface after the vertical holes were blasted, avoiding the problem of excessive clamping force caused by the incomplete formation of the free surface when the combined blast holes were blasted. This ensured that the blasting energy of the fan-shaped holes acted efficiently on the ore body, improving the crushing effect and reducing the proportion of large blocks.

[0044] The segmented delay design of the first-stage blast holes allows the blasting energy to be released segment by segment, avoiding the strong vibrations caused by concentrated energy accumulation, reducing disturbance to the surrounding rock, and simultaneously achieving orderly crushing and throwing of ore, preventing blockage of empty areas. The second stage involves detonating the vertical holes first, followed by the combined blast holes, combined with appropriate delayed detonation methods. This allows the cutting groove to gradually expand along a predetermined direction, ensuring a regular expansion shape. Simultaneously, the 25ms–50ms delay between segments ensures the continuity of blasting while preventing mutual interference between blasting energies from adjacent segments.

[0045] like Figures 1 to 5 As shown, this application provides another specific implementation method based on the above-described implementation method as follows: In S3, the bulk explosive is expanded ammonium nitrate explosive, which is loaded using a charging device; the detonating charge is a rolled emulsion explosive, which is placed at the bottom of the hole along with 2 to 3 electronic detonators; and detonating cord is laid along the entire length of the borehole.

[0046] The connection method of the detonation network is as follows: each electronic detonator is connected by a lead wire and connected to the blasting bus line. The detonation point is located inside the vein. The blasting cable is laid from the vein through the main roadway and the mining slope to the section connecting roadway. The blasting bus line is laid from the section connecting roadway to the blasting face.

[0047] In terms of improving loading efficiency and coupling, using bulk explosives in conjunction with a charging device allows for rapid and uniform loading of explosives into the borehole. The use of the charging device makes explosive loading more efficient, reducing the time and labor intensity of manual loading. Simultaneously, bulk explosives adhere better to the borehole wall, improving the coupling between the explosive and the ore, allowing the energy generated by the explosion to be more fully transferred to the ore, thus enhancing the blasting effect.

[0048] To ensure reliable initiation and full-length propagation of the detonation wave, the detonating charge uses rolled emulsion explosive, placed at the bottom of the borehole along with 2-3 electronic detonators, while detonating cord is laid along the entire length of the borehole. The emulsion explosive possesses excellent initiation performance and stability, ensuring reliable detonation at the bottom of the borehole. The use of electronic detonators allows for precise control of the detonation time, achieving millisecond-level differential control and improving blasting accuracy. The full-length laying of detonating cord ensures that the detonation wave propagates throughout the entire borehole, guaranteeing complete detonation of the explosive and improving blasting stability and energy utilization.

[0049] like Figures 5 to 7 As shown, this application provides another specific implementation method based on the above-described implementation method as follows: In S3, the millisecond-level differential control is as follows: in the first stage, the internal blast holes are detonated sequentially in segments with a delay of 25ms to 175ms; in the second stage, the upward vertical holes in different rows are detonated sequentially with a delay of 25ms to 150ms.

[0050] In controlling the superposition and dissipation of blasting stress fields, a precise delay sequence can ensure that the blasting stress fields of different boreholes coordinate with each other. A reasonable delay time allows the stress field generated by the first borehole to dissipate within a certain period of time, avoiding excessive stress concentration caused by the superposition of stress fields with those of subsequent boreholes. This reduces damage to the surrounding rock and the impact of blasting vibrations on the surrounding environment.

[0051] From the perspective of optimizing the rock fragmentation process, differential time delay control allows the energy generated by the explosive explosion to act more effectively on the rock. Under different time delays, the rock undergoes multiple impacts under different stress states, resulting in better fragmentation. Simultaneously, a reasonable time delay can also control the size of the rock fragments, reducing the proportion of large pieces.

[0052] In achieving directional rock movement, precise differential delay schemes can control the throwing direction and distance of rocks based on their mechanical properties and blasting design requirements. By adjusting the detonation sequence and delay time of different blast holes, rocks can be made to move in a predetermined direction, improving the throwing effect of ore, reducing ore accumulation in the blasting area, and facilitating subsequent mining operations.

[0053] like Figures 1 to 3 As shown, this application provides another specific implementation method based on the above-described implementation method as follows: Before S1, there is also a step of grouting pre-reinforcement of the fractured ore body.

[0054] In terms of improving the integrity and stability of fractured ore bodies, grouting can fill the joints and fissures within the ore body, binding loose ore particles together to form a relatively complete whole. This allows the ore body to better withstand external forces during drilling and blasting, reducing problems such as borehole wall collapse and surrounding rock instability caused by ore body fracturing.

[0055] From the perspective of improving geological conditions for drilling and blasting operations, pre-reinforced ore bodies are more suitable for these operations. A stable ore body ensures the quality and accuracy of drilling, reducing deviations and accidents during the drilling process. Simultaneously, during blasting, the integrity and stability of the ore body allow explosive energy to act more effectively on the ore, improving blasting results and reducing explosive consumption per unit.

[0056] In terms of reducing construction risks, grouting pre-reinforcement can fundamentally improve the geological conditions of fractured ore bodies, reducing the probability of accidents such as roof falls and spalling caused by ore body fracturing. This provides a safer working environment for construction personnel, ensures the smooth progress of construction, and improves the safety and reliability of the entire mining process.

[0057] like Figures 1 to 3 As shown, this application provides another specific implementation method based on the above-described implementation method as follows: The secondary expansion blasting method for cutting grooves in steeply inclined, fractured, thin ore bodies is applicable to segmented deep-hole blasting continuous mining methods for steeply inclined, fractured, thin ore bodies.

[0058] The geological conditions of steeply dipping, fractured, and thin ore bodies are unique, characterized by large dip angles, fractured rock masses, and relatively thin thickness. Conventional mining techniques may not be effective in handling these conditions, easily leading to problems such as high blasting restraint forces and roof collapse. This method, specifically designed for such ore bodies, fully considers their unique geological characteristics. Through rational borehole layout, staged blasting design, and charge and detonation network design, it achieves efficient and safe mining of this type of ore body, improving the adaptability of mining techniques to the ore body.

[0059] In segmented deep-hole blasting continuous mining technology, the problem of widening the initial cutting groove after it is formed in steeply inclined, fractured, thin ore bodies is a key challenge. This method systematically solves a series of problems caused by insufficient space in the primary cutting groove, such as reducing blasting clamping force and improving ore extraction efficiency. It provides an effective solution for segmented deep-hole blasting continuous mining technology for steeply inclined, fractured, thin ore bodies, and promotes the smooth implementation of this mining technology under specific ore body conditions.

[0060] In summary, compared with the prior art, the embodiments of this application have the following beneficial effects: 1. The combination of upward vertical holes and fan-shaped holes ensures expansion efficiency while avoiding excessive disturbance to the surrounding rock during blasting, reducing the risk of roof collapse. 2. A two-stage blasting method is adopted, with the first row of holes being piloted and subsequent rows being blasted sequentially, with a delay of 25ms to 50ms between rows. A 300ms jump segment is set between the second-stage vertical holes and the combined blast holes, and the detonation point is far from the working face, achieving safe and efficient expansion. 3. An emulsion explosive detonating charge + bulk expanded ammonium nitrate explosive + full-length detonating cord charging system is used. At the same time, in order to protect the rock drilling tunnel brow line and facilitate subsequent blast hole construction, the last row of blast holes uses decoupled charging. 4. After blasting, a three-dimensional model is constructed by laser scanning of the empty area to verify the expansion volume and ensure that the compensation space meets the requirements of continuous blasting of multiple rows of production holes. 5. It is compatible with segmented deep-hole mining technology. After trench expansion, it can achieve multi-row continuous blasting, which greatly improves mining efficiency and is suitable for efficient mining of steeply inclined, fractured, and thin ore bodies such as uranium ore.

[0061] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

[0062] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0063] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

Claims

1. A method for secondary blasting expansion of a cutting groove in a steeply inclined, fractured, thin ore body, characterized in that... Includes the following steps: S1. Design and construction of borehole layout: On the side wall of the empty area formed by the first cutting slot blasting, multiple rows of widening blast holes are arranged along the ore body strike. The blast holes include upward vertical holes and fan-shaped medium-deep holes. S2, Stage blasting design: The multi-row blasting holes are divided into two blasting stages for sequential blasting. In the first stage, at least one row of blasting holes closest to the empty area is blasted to perform preliminary blasting. In the second stage, the enlarged free surface formed by the blasting in the first stage is used to blast all subsequent blasting holes in one go. S3. Charge and initiation network design: Bulk explosives are used in conjunction with detonating cords and electronic detonators for continuous charging, and a decoupled charge structure is used for the borehole openings of adjacent roadways to protect the roadway brow line; the initiation network uses an electronic detonator initiation system to implement millisecond-level micro-delay control, realizing sequential initiation of boreholes between two blasting stages and within each stage.

2. The method for secondary expansion blasting of a cutting groove in a steeply inclined, fractured, thin ore body as described in claim 1, characterized in that, In S1, the row spacing of the multi-row expanded boreholes is 0.8m to 1.6m, the hole spacing is 0.8m to 1.6m, the hole diameter is 65mm to 80mm, and the bottom distance of the deep holes in the fan shape is 1.0m to 1.5m.

3. The method for secondary widening blasting of a cutting groove in a steeply inclined, fractured, thin ore body as described in claim 1, characterized in that... In S2, the first stage of blasting targets the first row of blast holes closest to the empty area, while the second stage of blasting targets the blast holes from the second to the sixth row.

4. The secondary blasting method for cutting a steeply inclined, fractured, thin ore body as described in claim 3, characterized in that... In S2, the first row of blast holes is arranged in a combination of upward vertical holes and fan-shaped holes; and in the second stage of blasting, the last row of blast holes located on the easternmost side is also arranged in a combination of upward vertical holes and fan-shaped holes.

5. The secondary blasting method for cutting a steeply inclined, fractured, thin ore body as described in claim 4, characterized in that... In S3, the method for the decoupled charge structure is as follows: fill the bulk explosive to a distance of 2.0m to 2.5m from the orifice, fill in 0.6m to 0.8m of gunning clay as a partition layer, then fill in 2 to 3 rolls of small-diameter explosive cartridges, and finally seal the orifice with 0.5m to 0.8m of gunning clay.

6. The secondary blasting method for cutting a steeply inclined, fractured, thin ore body as described in claim 3, characterized in that, In S3, in the design of the detonation network for the second stage of blasting, a delay jump of no less than 300ms is set between the upward vertical holes and the combined blast holes in the same row to ensure that all vertical holes in the row are detonated and form a new free surface before the combined blast holes in the same row are detonated.

7. The method for secondary widening blasting of a cutting groove in a steeply inclined, fractured, thin ore body as described in claim 1, characterized in that, In S3, the bulk explosive is expanded ammonium nitrate explosive, which is loaded using a charging device; the detonating charge is a rolled emulsion explosive, which is placed at the bottom of the hole along with 2 to 3 electronic detonators; and detonating cord is laid along the entire length of the borehole.

8. The method for secondary widening blasting of a cutting groove in a steeply inclined, fractured, thin ore body as described in claim 1, characterized in that, In S3, the millisecond-level differential control is as follows: in the first stage, the internal blast holes are detonated sequentially in segments with a delay of 25ms to 175ms; in the second stage, the upward vertical holes in different rows are detonated sequentially with a delay of 25ms to 150ms.

9. The method for secondary widening blasting of a cutting groove in a steeply inclined, fractured, thin ore body as described in claim 1, characterized in that, Before S1, there is also a step of grouting pre-reinforcement of the fractured ore body.

10. The method for secondary widening blasting of a cutting groove in a steeply inclined, fractured, thin ore body as described in claim 1, characterized in that, The method for secondary expansion blasting of cutting slots in steeply inclined, fractured thin ore bodies is applicable to segmented deep-hole blasting continuous mining methods for steeply inclined, fractured thin ore bodies.

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