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Sluice Well Structural Parameter Design — Heijinggang Broadcast
Shape Design: Striking a Balance Between Construction Convenience and Stability
Vertical drop shaft
Vertical shafts typically feature circular cross-sections, which provide excellent stability in rock formations due to their uniform stress distribution—making them particularly well-suited for mining areas with complex geological conditions and fractured rock. The circular design effectively disperses the impact force generated as ore descends, significantly reducing wear on the shaft walls and extending the structure's service life. While rectangular cross-sections offer a slight advantage in terms of construction convenience, their sharp corners tend to concentrate stress, leading to localized damage. As a result, rectangular sections are generally used only in scenarios where the rock formation is exceptionally intact and intended for short-term applications. In practice, engineering decisions should be made by carefully considering factors such as rock hardness and the degree of joint development. For instance, in hard, stable granite formations, circular cross-sections can reduce maintenance costs by more than 30% compared to rectangular ones.
Tilting Trough Feeder
Inclined chutes typically feature either rectangular or arched cross-sections. The rectangular design is particularly convenient for construction surveying and the installation of support structures, making it widely used in gently inclined ore bodies. This design can significantly shorten the length of transport roadways, thereby reducing development costs. On the other hand, the arched cross-section optimizes the structural mechanics by converting the vertical pressure exerted by the ore on the well walls into circumferential stress within the arch, enhancing overall stability. As such, it is ideally suited for deep mines with high ground pressures. Engineering practice has shown that inclined chutes aligned along the strike of rock layers achieve 20% higher excavation efficiency compared to vertical chutes—but careful control of the dip angle (greater than 60°) is essential to prevent ore accumulation and subsequent blockages.
Segmented Drop Shaft
The segmented direct chute well is a specialized type of chute well designed by offsetting the upper and lower openings of each stage by a certain distance, enabling segmented, relay-style transportation. At its core, this design breaks away from the traditional vertical-through structure of conventional direct chute wells, achieving independent operation across multiple stages via spatial misalignment. While retaining the efficient, gravity-driven transport characteristics of straight chute wells, it also addresses the critical challenge of coordination in multi-stage mining operations. This innovative design is particularly well-suited for mines with complex geological conditions and those conducting simultaneous production at multiple levels. By implementing staged control, it minimizes the potential impact area of accidents occurring in any single chute section, thereby enhancing the overall reliability of the system.
Stepped Drop Shaft
The stepped chute system is a segmented ore-handling system designed to accommodate complex geological conditions. Its key feature lies in the significant lateral offset between the upper and lower stage chutes. Ore from the upper section is transported via motorcars or mine cars connected by horizontal drifts, before being transferred through unloading chambers into the lower-stage chute for continued downward movement. This "segmented relay + horizontal transfer" design breaks away from the conventional single vertical or inclined-through model of straight or sloped chutes, allowing for flexible spatial adjustments that optimize adaptability to fractured rock formations and gently dipping ore bodies.
02
Size Determination: Parameter Matching Centered on Block Size
Through the engineering significance of the coefficient
The core of chute design lies in ensuring smooth ore passage while preventing large chunks from getting stuck. The through coefficient (d/α, where d is the chute diameter or minimum side length, and α is the maximum allowable block size) must be strictly controlled within the 3-to-5 range. If the through coefficient falls below 3, the risk of blockage rises significantly—this was notably observed at a certain iron mine, where the chute diameter was only 2.5 times the block size, resulting in an average of 12 blockages per month and severely disrupting production flow. Conversely, exceeding 5 times not only increases excavation costs but also enlarges the area of wear on the chute walls. In practical design, it’s essential to integrate the block-size distribution curve generated by the blasting process and employ probabilistic statistical methods to determine an optimal chute size. For instance, for ores with a maximum block size of 600 mm, the chute diameter should ideally be set between 2.4 and 3.0 meters.
The Influence of Cross-Sectional Shape on Dimensions
The circular cross-section offers the highest efficiency in utilizing its effective flow area, providing 15% greater throughput compared to a rectangular section at the same dimensions. Additionally, it facilitates easy implementation of center-dropped ore discharge, reducing uneven load distribution and wear. In contrast, rectangular sections must meet size requirements separately for both width and height—typically, the height is set to 2 to 2.5 times the block size, while the width is chosen as 2.5 to 3 times the block size—resulting in a "short and stout" profile. This design helps prevent ore blockages caused by an imbalanced height-to-width ratio. For instance, when a certain copper mine restructured its rectangular chutes by adjusting the height-to-width ratio from 1.8 to 1.2, the frequency of blockage-related incidents dropped by 60%, clearly demonstrating the critical importance of optimizing cross-sectional proportions.
03
Tilt Angle Design: Critical Parameters Based on Granular Dynamics
The mechanical essence of >60°
The design of the inclined chute angle must overcome the dual thresholds of the ore's natural angle of repose (approximately 35–45°) and its rolling friction angle (about 15–20°), ensuring that the ore descends in a combined sliding-and-rolling motion. When the inclination angle exceeds 60°, the component of gravity acting along the chute wall significantly surpasses both frictional forces and inter-particle cohesive forces, effectively preventing fines from sticking together and large chunks from getting lodged. Numerical simulations reveal that at a 60° incline, the average flow velocity of the ore reaches 4 m/s—representing a 25% increase compared to 50°—and the probability of blockage drops by 40%. For ores with higher clay content, the inclination angle should be further increased to above 65° to counteract the viscous effects of clay minerals.
Angle Optimization in Engineering Cases
A certain lead-zinc mine was originally designed with a dip angle of 55°, but after production began, it frequently experienced issues with fine ore sticking and causing blockages. On-site testing revealed that when the ore moisture content reached 8%, the critical starting angle for flow increased to 62°. As a result, the dip angle was adjusted to 63°, and a vibrating discharge device at the bottom of the shaft was installed, effectively resolving the blockage problem. Meanwhile, another gold mine adopted a segmented inclined chute system: the upper section featured a 60° dip angle to accelerate ore flow, while the lower section was set at 65° to better handle impact forces at the transition point. After optimization through ANSYS simulations, the wear on the chute walls was reduced by 22%, extending the equipment’s service life by an additional 1.5 years.
04
Quantity Planning: Systems Engineering with Multi-Factor Coupling
Principle of Production Capacity Alignment
The primary task in planning the number of run-of-mine chutes is to precisely match them with the mine’s production capacity, ensuring efficient and stable ore transportation. The throughput capacity of a single chute must take into account the mine’s daily output as well as the unevenness factor for ore discharge (typically ranging from 1.2 to 1.5), which helps address peak demand periods. The calculation formula is: N = Q / (q × k × t), where Q represents the mine’s daily production volume, q is the hourly throughput capacity of a single chute (usually between 300 and 800 tons/hour, depending on equipment selection and chute design), k denotes the time utilization rate (commonly between 0.7 and 0.8, reflecting non-productive downtime due to maintenance or equipment failures), and t stands for the daily working hours (often set at 16 to 20 hours). For instance, consider a large copper mine with an annual output of 3 million tons. Based on calculations, its daily output is approximately 9,000 tons. If the designed throughput capacity of a single chute is set at 500 tons/hour, plugging these values into the formula reveals that two main chutes are required, creating a “one-in-use, one-on-standby” redundancy design. This setup effectively mitigates disruptions caused by equipment maintenance or unexpected breakdowns, thereby ensuring the mine’s continuous and stable operation.
Quantitative Decision-Making Under Complex Conditions
In actual mining operations, the demand for separate ore extraction and the significant differences in ore and rock properties greatly influence decisions regarding the number of decline shafts. When processing multiple types of ores separately, to prevent mixing of varying ore qualities and thereby reduce both beneficiation complexity and costs, it is essential to establish dedicated decline shafts. For instance, a polymetallic mine faced distinct challenges due to differences in the properties of copper and zinc ores as well as their respective beneficiation processes. As a result, two additional specialized decline shafts were constructed. Although this increased initial capital investment in infrastructure, the plant’s recovery rate improved by 3%, yielding substantial long-term economic benefits. From the perspective of ore and rock properties, hard ores cause minimal wear on decline shafts, allowing for more concentrated placement to lower development costs. In contrast, softer ores are prone to causing blockages and accelerated wear, necessitating a more dispersed arrangement to reduce the load on individual shafts. A certain coal mine, recognizing variations in coal seam hardness, reduced the spacing between decline shafts from 80 meters to 50 meters. This adjustment effectively minimized incidents of blockage and wear, cutting accident rates by up to 50%—a move that significantly enhanced both production safety and operational continuity.
Dynamic Programming in the Age of Intelligence
As the pace of mining intelligence accelerates, discrete element software such as PFC provides robust technical support for stope shaft planning. By simulating ore flow characteristics under different numbers of stope shafts, precise planning can be achieved. At one intelligent mine, a digital twin model was used to compare the operational efficiency of 1 to 4 stope shafts. The analysis revealed that three stope shafts resulted in the lowest system energy consumption and minimized the risk of blockages—representing a reduction of one shaft compared to conventional design practices, thereby saving 2 million yuan in infrastructure costs. Meanwhile, integrated with IoT technology, the mine continuously monitors real-time parameters such as ore flow rate, pressure, and wear levels in each stope shaft, dynamically adjusting load distribution to ensure the entire system operates at peak efficiency at all times. This approach not only achieves cost reduction and efficiency gains but also safeguards safe production, fulfilling the dual objectives of operational optimization and enhanced safety.
