The Core Principle for Balancing Transportation Efficiency and Engineering Costs

Coordinated Design for Short-Distance Transportation and Low Engineering Volume

In mining operations, the selection of chute locations plays a decisive role in determining overall transportation efficiency and project costs. One of the core objectives is to minimize the transportation distances between upper and lower stages. By leveraging advanced 3D orebody modeling techniques and development system simulation software, it becomes possible to precisely identify the optimal connection points between each intermediate-level dumping point and the main transportation system. For instance, in the mining plan for a certain metal mine, meticulous modeling and analysis of the orebody clearly defined the production locations and flow directions of ore from different intermediate levels, thereby preventing inefficient scenarios such as reverse transportation—where ore from an upper stage would need to be redirected back to a lower-stage chute.

To further enable quantitative analysis, a transportation-work-minimization algorithm can be employed in practice. This algorithm comprehensively considers factors such as ore distribution, tunneling costs, and equipment operational energy consumption to determine the optimal vertical spacing along the ore body's strike direction. For instance, in a large-scale mine, after implementing this algorithm, the average haul distance per section was reduced by 15%–20% compared to conventional layouts, while the overall volume of development tunnels decreased by approximately 30%. As a result, not only were transportation costs significantly lowered, but the speed of ore transfer was also accelerated, leading to improved overall production efficiency.

A Dual Consideration of Construction Convenience and Production Safety

When selecting a site, priority should be given to areas with gentle surface topography and well-connected underground rock formations, which facilitate efficient operation of construction equipment. For instance, excavating vertical skip shafts requires stable rock dip angles to prevent increased costs for shaft wall support due to developed jointing; meanwhile, the dip angle for inclined skip shafts must be designed to exceed 60°, while also avoiding unstable strata such as quicksand layers, thereby minimizing risks like water inrush and collapse during construction.

During the production phase, to ensure the safe and stable operation of the chute shaft, a buffer ore layer—approximately one-third of the shaft's depth—can be预留 to minimize the impact force of ore discharge, thereby reducing wear on the shaft walls. A certain mine has successfully implemented this measure in its actual operations, effectively extending the service life of the chute shaft by 2 to 3 years, cutting down on maintenance frequency and costs, and ensuring both production continuity and safety.

02 Key Technical Requirements for Geological Condition Compatibility

Quantitative Assessment Criteria for Rock Mass Stability

The stability of a chute largely depends on the strength of the surrounding rock strata; therefore, when selecting a site, it is essential to conduct a quantitative assessment of the rock’s stability. Generally speaking, chutes should be located in continuous rock formations with a uniaxial compressive strength greater than 80 MPa and joint spacings exceeding 1.5 meters. This criterion is not arbitrary—it stems from extensive engineering experience and practical observations. In the actual evaluation process, engineering geological surveys and sonic testing are commonly employed techniques. Geological surveys provide detailed insights into the lithology, structure, and other characteristics of the strata, while sonic testing measures the velocity of elastic waves in the rock, allowing engineers to infer both the rock’s integrity and its overall strength.

For instance, in a certain metal mine's mining project, the initial plan was to place the skip shaft at a location that seemed suitable. However, after detailed geological surveys and sonic testing revealed a fault fracture zone wider than 2 meters in that area, it became clear that constructing the skip shaft there would severely compromise the stability of the shaft walls, leading to frequent issues such as wall collapses and blockages. As a result, the project team reassessed the site selection and ultimately decided to relocate the skip shaft into silicified marble, where the rock boasts an impressive compressive strength of 120 MPa, with widely spaced joints and excellent overall integrity. Compared to the original plan, positioning the skip shaft in this new location reduced the frequency of shaft wall maintenance by 60% and slashed the incidence of blockage incidents by 40%, effectively ensuring the mine's smooth and uninterrupted production.

However, in some special cases, the skip shaft may have to pass through weak rock layers. In such instances, effective support measures must be implemented to ensure the safety of the shaft. Common practices include using reinforced concrete lining or combining anchor bolts with cable anchors for support, with a minimum lining thickness of 0.8 meters. These robust support structures not only enhance the load-bearing capacity of the shaft walls but also effectively resist deformation and failure of the surrounding rock, providing a reliable safeguard for the stable operation of the skip shaft.

Engineering Strategies for Avoiding Unfavorable Geological Features

In addition to focusing on the stability of rock strata, it is also necessary to implement effective strategies to avoid unfavorable geological features. For zones with well-developed structures—such as faults classified as F3 or higher—it is crucial to maintain a safety distance of at least 15 meters. This is because faults rated F3 and above typically exhibit significant size and have a pronounced destructive impact on rock masses, severely compromising their overall stability. If a chute is located too close to such faults, the fault's movement during mining operations could trigger deformation and fracturing of the surrounding rock, ultimately leading to damage of the chute itself.

When encountering karst regions, it is crucial to thoroughly investigate the distribution of cavities beforehand. In karst areas, sinkholes and corrosive fractures can severely weaken and make the rock mass fragmented and uneven, posing significant risks to both the construction and operation of decline shafts. At one mine, during the construction of a decline shaft, neglecting proper karst exploration led to a mining leakage accident just three months after the shaft was put into operation. A substantial amount of ore leaked out through the sinkhole, resulting not only in resource wastage but also severely disrupting production schedules. Subsequent efforts to address this incident required extensive manpower, resources, and time, ultimately driving up remediation costs by an additional 2 million yuan. This case vividly underscores the critical importance of conducting geological surveys ahead of time. To prevent similar accidents, when dealing with karst regions, engineers can adopt a pre-treatment approach by filling cavities with steel-fiber reinforced concrete, thereby enhancing the overall integrity and stability of the rock mass and ensuring the safe operation of the decline shaft.

Formations with water inflow exceeding 5 m³/h also require careful handling. Constructing a skip shaft in such formations can lead to water scouring the shaft walls, weakening the rock strength and increasing the risk of collapse. To address this issue, it is necessary to install surrounding cutoff drifts and drainage holes around the skip shaft, diverting groundwater away from the shaft and preventing water from eroding the shaft walls.

03 Principles for Precise Localization of Mineral Body Spatial Relationships

The Technical Advantages of Downhole Surrounding Rock Arrangement

The spatial relationship between the draw shaft and the ore body is a critical factor that cannot be overlooked during site selection. A key principle is to prioritize placing the draw shaft in the stable surrounding rock on the footwall, based on the geometry of the ore body itself. In practice, for steeply inclined ore bodies, the draw shaft should be positioned at least 10 meters away from the ore-body boundary; for gently inclined ore bodies, this distance must be increased to 20 meters. These specific spacing requirements are carefully considered to prevent the shaft from intersecting the ore body. Once the shaft penetrates the ore body, it becomes necessary to leave behind protective pillars, which would inevitably reduce the overall recovery rate of the ore. According to relevant data, properly positioning the draw shaft can boost the ore recovery rate by 3% to 5%.

Taking a certain lead-zinc mine as an example, the ore body in this mine dips at an angle of 65°, classifying it as a steeply inclined deposit. During the mine's extraction process, the skip shaft was strategically placed within the hanging wall surrounding rock, resulting in an average reduction of 12% in the length of transportation drifts at each level. This not only lowered transportation costs but also significantly boosted operational efficiency. Meanwhile, since the skip shaft does not penetrate the ore body, there’s no need to leave behind protective pillars within the ore itself, thereby increasing the annual ore-handling capacity of a single shaft by 10%. This case vividly demonstrates the remarkable advantages of placing the skip shaft in the hanging wall, particularly in enhancing both transportation efficiency and ore-processing capacity.

However, in certain special cases—such as when the surrounding rock is unstable while the ore body itself is dense and solid—careful consideration can be given to placing the skip shaft directly within the ore body, particularly for massive sulfide ore bodies. Yet, under these circumstances, it is essential to simultaneously implement shotcrete and anchor reinforcement measures for the shaft walls. Such reinforcement not only enhances the stability of the shaft walls but also prevents wall collapse, thereby ensuring the safe operation of the skip shaft.

Multi-stage Collaborative Spatial Layout Optimization

In mines that simultaneously produce ore from multiple levels, adopting a segmented chute structure can effectively optimize space layout and enhance production efficiency. The segmented chute structure primarily includes two types: the cascade type and the relay type. When designing the segmented chute system, the offset distance between the upper and lower chutes must be at least 15 meters to prevent interference between the two sections and ensure smooth ore flow. Additionally, when using inclined chutes to connect the upper and lower chutes, the angle of inclination should be maintained within the range of 45° to 55°. This specific angle range not only guarantees efficient ore descent but also prevents the ore from sliding too rapidly, thereby minimizing excessive impact on the chutes.

A certain copper mine implemented a relay-type skip system during its mining operations, achieving excellent results. This system enables independent control of ore discharge from different levels, and even if one shaft encounters a failure, adjacent levels can still maintain up to 60% of their original production capacity. Compared to the traditional single-level system, the reliability of this relay-type skip system has improved by 30%. This case clearly demonstrates the critical role of multi-stage, coordinated spatial layout optimization in enhancing the reliability of mine production. By carefully designing segmented skip structures, mines can significantly boost productivity and reliability while reducing operational costs—providing a robust foundation for the sustainable development of mining operations.

04 Interference Control Between the Unloading System and Transport Roadways

Functional Zoning Design for the Ore Discharge Point Arrangement

The rational arrangement of the ore-discharging point is a critical step in minimizing transportation disruptions and reducing mine dust pollution. From the perspective of functional zoning, sufficient safety distance should be maintained between the ore-discharging chamber and the main transport roadway—typically, this distance should be ≥30 meters. This is because the ore-discharging process generates significant amounts of mine dust and noise; if the discharging point is located too close to the main transport roadway, it could severely compromise the safety and efficiency of transportation operations. In practice, when spatial constraints prevent meeting the direct spacing requirement, an alternative approach is to connect the discharging area with auxiliary transport roadways via connecting tunnels, thereby creating an independent buffer zone for ore unloading.

In the mining practice of a certain metal mine, the mine initially positioned the ore-discharge point right next to the main transport roadway, which led to a significant increase in the failure rate of transportation equipment—statistically, the failure rate rose by 25% compared to normal conditions. At the same time, dust pollution became extremely severe, not only compromising the health of workers but also negatively impacting the lifespan of the equipment. Later, the mine addressed these issues by adding isolation wind walls and installing dust-control units, thereby optimizing and upgrading the ore-discharge area. After the renovation, dust pollution was reduced by 70%, and transportation efficiency gradually returned to its designed level.

To further control mineral dust pollution, when unloading points are arranged on one side of the transport roadway, they should be equipped with an air curtain dust removal system and an automatic spray mist suppression system. The air velocity of the air curtain dust removal device must be ≥8 m/s, creating an effective air barrier that prevents mineral dust from spreading into the transport roadway. Meanwhile, the automatic spray mist suppression system can activate automatically during the unloading process, using fine water droplets to settle the dust particles and keeping the dust concentration below 2 mg/m³—thus providing a relatively clean environment for transportation operations.

Equipment Matching and Process Optimization

Equipment matching and process optimization are crucial methods for improving ore-unloading efficiency and reducing transportation disruptions. The size of the unloading chute must be properly aligned with the ore-discharging equipment to ensure smooth material discharge. For instance, a 20-ton electric scraper loader requires an unloading chute width of at least 4 meters to guarantee seamless operation during unloading, preventing difficulties caused by a chute that’s too narrow—and ultimately avoiding potential blockages in the transportation system.

When it comes to controlling the pace of ore unloading, using hydraulic automatic gates is a highly effective approach. Compared to manual operation, hydraulic automatic gates allow for more precise control over the unloading speed and flow rate, thereby preventing transportation bottlenecks caused by the inherent instability of human-operated systems. Before the upgrade, a certain lead mine frequently experienced issues with unloading speeds that were either too fast or too slow due to its reliance on manual control, leading to queues of transport vehicles and significantly reducing overall efficiency. After the transformation, the mine implemented hydraulic automatic gates to regulate the unloading rhythm, complemented by an intelligent scheduling system that synchronized the unloading process with the operational cycles of the transport vehicles. As a result of these optimized measures, the mine’s average daily throughput per shaft increased from 3,000 tons to 3,600 tons, while the frequency of transportation disruptions dropped by 50%. This not only yielded substantial economic benefits but also markedly improved production efficiency.

Moreover, the application of an intelligent scheduling system is also key to achieving equipment matching and process optimization. This system can monitor in real time the location, status of transport vehicles, and the operational conditions at unloading points, enabling it to rationally arrange transportation tasks, optimize the allocation of transport resources, and further enhance overall production efficiency.

05 Adaptation Strategies for Special Operating Conditions

Engineering Strategies for Complex Terrain Conditions

In mountainous mines with a surface elevation difference exceeding 200 meters, a stepped chute system can be employed for segmented material transfer, with belt conveyors connecting the intermediate sections to address the impact and wear issues associated with long-distance chute discharge. For instance, a certain tungsten mine, situated within a mineral body featuring a 350-meter elevation drop, implemented a three-level stepped chute system, with each stage designed to handle a vertical drop of no more than 120 meters. Combined with a carefully engineered buffer storage bin, this approach reduced the wear rate on the chute walls by 40% and improved the overall system reliability by 60%.

Monitoring and Feedback on Dynamic Geological Conditions

A real-time monitoring system for the stability of the stope surrounding rock has been established, utilizing strain gauges, inclinometers, and vibration sensors to continuously collect data such as wall displacement (warning threshold: ±3 mm/month) and stress variations (warning threshold: ±5 MPa). After implementing this system at a certain copper mine, a trend of rock layer sliding at the bottom of the stope was detected three weeks in advance. Prompt reinforcement measures, including anchor cable installation, were taken, effectively preventing a major safety incident. This highlights the critical role of dynamic monitoring in handling complex geological conditions.

Scientifically determining the location of a skip shaft is a critical step for the efficient and safe operation of underground mines, requiring systematic optimization across transportation efficiency, geological safety, orebody relationships, and production interference. By integrating advanced engineering-geological surveys, 3D simulation modeling, and intelligent monitoring technologies, the scientific rationale behind skip shaft placement can be significantly enhanced, laying a robust foundation for the mine's entire lifecycle operations. In practice, site selection should be tailored to specific orebody characteristics and mining processes, ensuring personalized solutions that strike the optimal balance between economic benefits and safety performance within the framework of technical standards.