I. Reservoir Size: A Fundamental Constraint for Equipment Selection

(1) Matching Reserve Volume with Economic Scale

Mineral deposit reserves play a decisive role in mine operations—they serve as a precise measuring tool, directly determining the mine's lifespan and the scale of its extraction activities. Moreover, they form the core basis for equipment selection. When a mine’s industrial reserves surpass the critical threshold of tens of millions of tons, the demands on equipment performance and efficiency for mining operations naturally escalate. At this point, large-tonnage equipment, with its outstanding single-trip transportation capacity, becomes essential for significantly reducing the unit cost of mineral and rock extraction.

Take, for instance, an open-pit mine processing over 5 million tons annually. If 50-ton mining trucks are chosen to handle the transportation tasks, meeting production demands might require as many as 30 vehicles. Such a large fleet not only drives up equipment acquisition costs but also makes equipment management exceptionally complex, significantly increasing scheduling challenges and, consequently, soaring operational expenses. In contrast, switching to 200-ton mining trucks would allow the same volume of transport to be achieved with just 8 to 10 vehicles. This approach dramatically reduces the number of equipment units, simplifies management, and leverages economies of scale to effectively lower both equipment depreciation costs and overall operating expenses per ton of ore or rock—ultimately boosting the economic efficiency of mining operations.

Reserve estimation is not a simple matter of numerical tallying—it’s a task that demands significant technical expertise. It requires the precise integration of two critical indicators: the cutoff grade and the industrial grade. The cutoff grade serves as the key threshold that distinguishes ore from waste, and even minor fluctuations in its value can profoundly impact the amount of recoverable reserves. For instance, in copper mine operations, if the cutoff grade rises from 0.4% to 0.6%, the recoverable reserves could drop by as much as 20%. This means that equipment originally planned for deployment might end up operating with excess capacity, leading to wasted resources. Conversely, setting the cutoff grade too low could result in an excessively high dilution rate, causing an overabundance of waste rock to be processed alongside valuable ore. Such inefficiencies would reduce the actual volume of usable ore handled by the equipment, diminishing overall equipment utilization and driving up unnecessary energy consumption and operational costs. Therefore, during reserve calculations, it’s essential to carefully consider all relevant factors and scientifically determine both the cutoff and industrial grades—ensuring that equipment configurations align precisely with the true recoverable reserves, thereby optimizing mining operations for both efficiency and cost-effectiveness.

(II) Equipment Adaptability to Reservoir Distribution Patterns

The distribution pattern of the ore body is like a unique code bestowed upon the mine by nature—its distinct shapes determine both the operational approach of loading equipment and the selection criteria for transportation vehicles during the mining process. Layered ore bodies, with their regular forms and stable distribution, resemble vast "mineral plains," making them ideal for large-scale operations conducted by advanced stripping equipment. Under these favorable conditions, electric shovels with bucket capacities ranging from 10 to 15 cubic meters can leverage their robust digging power to efficiently extract ore. Meanwhile, matching 200- to 300-ton-class haul trucks act as "mineral giants," swiftly transporting massive amounts of ore to designated locations, ensuring that mining operations remain smooth and highly productive.

However, vein-type ore bodies are entirely different—they feature a winding, meandering trend and exhibit highly variable thicknesses, resembling a mysterious underground labyrinth. Faced with this intricate mineral structure, the limitations of large-scale equipment become glaringly apparent. That’s when hydraulic shovels with bucket capacities of 3 to 5 cubic meters come into their own, thanks to their compact and agile design, allowing them to navigate effortlessly through narrow, ever-changing spaces while precisely loading the ore. Meanwhile, 60- to 100-ton mining trucks, with their smaller profiles and exceptional maneuverability, can swiftly traverse complex transportation routes, promptly hauling away the loaded ore and significantly enhancing both operational flexibility and efficiency.

Mineral bodies with high gangue content pose significant challenges to mining operations. During extraction, frequent encounters with gangue require miners to switch ore-rock transportation routes repeatedly. In such scenarios, small-tonnage mine cars demonstrate a unique advantage in maneuverability—they can swiftly adapt to route changes, minimizing wait times and preventing equipment downtime or production delays caused by untimely route adjustments. This, in turn, effectively boosts overall mining efficiency. In mines where ore reserves are distributed in complex and ever-changing patterns, only by thoroughly considering the specific characteristics of each mineral body and selecting equipment that perfectly matches those features can mining operations proceed smoothly, ultimately enabling efficient extraction and sustainable development of the mine.

II. Burial and Mining Depth: Technical Limitations of Geological Conditions

(1) The Impact of Burial Depth on Extraction Methods

Burial depth serves as a critical threshold set by nature for mine extraction, profoundly influencing the choice of mining methods—and ultimately determining the direction of equipment selection. When ore deposits are located in shallow areas, typically defined as having a burial depth of less than 200 meters, open-pit mining becomes the preferred option due to its high efficiency and low-cost advantages. Under these mining conditions, the slope for haul truck operations usually does not exceed 8%, which falls well within the climbing capacity of 200-ton class trucks—whose maximum gradeability is around 10%. As a result, these trucks can effortlessly handle transportation tasks. Meanwhile, large electric shovels thrive in the open, spacious environment, fully leveraging their formidable digging power to achieve highly efficient ore extraction and transportation operations.

However, when the burial depth of the ore deposit exceeds 500 meters, the situation undergoes a dramatic shift. At this point, underground mining becomes a more suitable option—but it also introduces a whole new set of challenges. Underground mining spaces are relatively confined, with both the width and height of tunnels imposing strict limitations on the size of mine cars and buckets. To accommodate these tight conditions, operators typically opt for articulated mine cars weighing under 60 tons. These compact vehicles are highly maneuverable, allowing them to navigate flexibly through narrow tunnels with ease. Meanwhile, the accompanying buckets usually have a capacity no greater than 5 cubic meters, ensuring that loading operations can be carried out smoothly within the limited space.

For example, an iron ore mine is buried as deep as 800 meters. After a comprehensive assessment, the mine has adopted the pillarless sublevel caving method for underground mining. When it comes to equipment selection, a 4-cubic-meter-capacity loader and 40-ton-class mine cars were chosen. This decision was made because the mine’s tunnel dimensions are 4m × 4.5m—allowing this particular equipment combination to maximize mining efficiency while ensuring safe operations. If larger mine cars and loaders were selected, they wouldn’t only fail to maneuver smoothly within the tunnels but could also pose safety risks and reduce overall mining productivity.

(II) Matching Mining Depth with Equipment Power

As mining depth continues to increase, the distance that haul trucks need to climb also grows longer, placing higher demands on the power of the equipment. In open-pit mining, there’s a clear pattern: for every 100-meter increase in mining depth, the truck’s speed when fully loaded uphill drops by approximately 15%. To maintain transportation efficiency and ensure smooth mine operations, it’s essential to boost the engine’s power output. Typically, this means upgrading from an engine rated at 1,000 horsepower to one delivering 1,500 horsepower or more—only then can the transportation needs of deep-mining operations be effectively met.

In addition to engine power, the high-temperature environment of deep mining is also a critical issue that cannot be overlooked. As mining depth increases, underground temperatures gradually rise, posing a severe challenge to the equipment's cooling systems. Take the hydraulic system of the bucket as an example—under high-temperature conditions, the hydraulic oil tends to heat up rapidly. If cooling isn’t handled promptly, the oil temperature can soar, causing sluggish operation of the hydraulic system and significantly reducing digging efficiency. Therefore, it’s essential to equip the bucket’s hydraulic system with a higher-capacity cooling device to enhance heat dissipation, ensuring that the hydraulic system can maintain optimal performance even in extreme heat environments.

During deep-level copper mining operations, as the mining depth reached 1,000 meters, the underground temperature exceeded 35°C. As a result, the original mine car engines experienced insufficient power when climbing slopes, leading to a significant drop in transportation efficiency. At the same time, the bucket hydraulic system frequently malfunctioned, causing sluggish movements that severely disrupted production schedules. To address these issues, the mine upgraded the mine car engines, increasing their power output to 1,800 horsepower, and installed high-capacity cooling systems for the bucket hydraulic units. Following these upgrades, the mine cars’ transportation efficiency was markedly improved, while the bucket hydraulic system now operates smoothly and reliably, ensuring the mine’s continued ability to maintain normal production.

III. Mining Bench Height: A Matching Parameter for Equipment Performance

(1) Stairway Height and Geometric Matching with Load-Supporting Equipment

The mining bench height is a critical geometric parameter in open-pit mining, profoundly influencing the selection of loading and transportation equipment as well as operational efficiency. According to open-pit mine design standards, the bench height must adhere to the principle of "being no less than two-thirds of the excavator's push-shaft height, yet not exceeding the maximum digging height." This regulation is grounded in both solid scientific principles and practical considerations. When the bench height meets this criterion, the excavator can perform loading operations more smoothly during its work cycle, effectively preventing dead zones or inefficiencies caused by improper digging heights. As a result, the bucket achieves a higher filling coefficient during loading, fully leveraging the excavator's inherent operational capabilities.

Take a certain model of excavator as an example: its push-pull arm height is 4.5 meters, while its maximum digging height reaches 9 meters. According to the above-mentioned standards, the reasonable range for the step height applicable to this excavator is 3 to 9 meters. In actual operations, when the step height is set at 6 meters, extensive statistical analysis of practical data reveals that the bucket's filling coefficient can reach up to 0.9. This means that during each loading operation, the bucket can be nearly fully loaded, significantly boosting loading efficiency. For instance, if this excavator is equipped with a 20 cubic meter bucket, and considering a mineral density of 2.5 tons per cubic meter, the amount of ore loaded in a single scoop could reach as high as 50 tons.

After completing the loading operation, the ore needs to be transported via mine cars to the designated location. At this stage, selecting the right tonnage for the mine cars is crucial to ensure efficient transportation. Based on experience, to prevent excessive waiting times caused by oversized mine cars—thereby avoiding disruptions to overall production efficiency—the optimal choice is to use 60- to 80-ton capacity mine cars. This ensures that each car can be fully loaded within just 3 to 4 shovelfuls, seamlessly connecting the loading and transportation processes and maintaining a smooth flow throughout the entire mining operation.

(II) The Impact of Step Stability on Equipment Load

The stability of benches is a critical factor that cannot be overlooked in mining operations—it is closely linked to bench height and directly influences the load-bearing capacity of both loading and transportation equipment. When the bench height exceeds 15 meters, it falls into the category of high benches. During high-bench mining, large rock fragments often form after blasting, with particle sizes frequently surpassing 1.5 meters. The presence of these oversized rocks places even greater demands on the structural strength of the bucket. To tackle this challenge, buckets are typically constructed using high-strength, wear-resistant steel, featuring a yield strength of at least 800 MPa. This material effectively withstands the impact and abrasion caused by large rock fragments, ensuring that the bucket can operate reliably even under harsh working conditions.

Meanwhile, since large rocks can generate significant impact loads on mine cars during loading and transportation, the bottom plates of the mine cars also require reinforcement. By using thicker bottom plate materials and optimizing the structural design, we can enhance the load-bearing capacity of the mine car floor, enabling it to withstand the impact of large rocks, thereby extending the service life of the mine cars and ensuring the safety and reliability of the transportation process.

On the contrary, when the step height is below 8 meters, it is classified as low-step operation. In low-step environments, small-scale loading equipment excels due to its flexibility and adaptability, delivering excellent operational performance. However, low-step operations often require an increased number of working platforms to meet mining demands. This, in turn, leads to longer travel distances for haul trucks, thereby slightly reducing transportation efficiency. Under these circumstances, selecting 40-to-60-ton haul trucks can help strike a balance between transportation efficiency and equipment investment costs. Moreover, the enhanced maneuverability of smaller haul trucks enables them to navigate swiftly through complex operational settings, easily adapting to the frequently changing transport routes typical of low-step mining. At the same time, their relatively lower tonnage also helps cut down both capital and operating expenses, ultimately boosting the economic viability of mine operations.

IV. Mining Year and Production Capacity: Dynamic Balance of the Engineering Plan

(1) Quantitative Requirements for Production Capacity Based on Equipment Quantity

The annual mining output and production capacity are crucial elements in mine operation planning—they are closely interconnected, jointly determining equipment selection and configuration, and profoundly influencing the mine's economic efficiency and sustainable development. From a quantitative perspective, calculating the service life of a mine is closely tied to factors such as reserves, recovery rate, annual output, and waste rock inclusion rate. Among these, annual output—essentially the production capacity—plays a key quantitative role in deciding the number of equipment required.

According to the mine service life formula (where Q represents reserves, in units of 10,000 tons; η is the recovery rate, in %; A is the annual production capacity, in units of 10,000 tons per year; and e is the waste rock inclusion rate, in %), we can clearly see the critical importance of the production capacity A throughout the entire calculation process. When the designed annual output A changes, the number of equipment configurations must also be adjusted accordingly to meet production demands.

Suppose a mine has reserves Q of 200 million tons, with a recovery rate η set at 90% and a waste-to-ore ratio e of 5%. When the designed annual production capacity A is 10 million tons, substituting these values into the formula yields a mine life span N of approximately 17.14 years. In this scenario, if 200-ton mining trucks are selected, and considering each truck achieves an annual efficiency of about 500,000 tons, meeting the annual transportation demand of 10 million tons would require deploying 20 such trucks. This is because each truck can transport 500,000 tons of ore per year, and the combined capacity of 20 trucks—totaling 10 million tons annually—will perfectly align with the mine’s production targets, ensuring smooth operations and timely completion of the mining task.

However, if we increase the capacity of the mine cars to 300-ton class, the annual efficiency per car will correspondingly rise to 700,000 tons. At this point, to meet the same annual production demand of 10 million tons, calculations show that only about 15 mine cars would be needed. Compared to the 200-ton class, using 300-ton mine cars reduces the number of equipment units by 5, while also cutting equipment investment by approximately 15%. This not only lowers the initial cost of acquiring the equipment but also decreases the workload associated with maintenance and management, ultimately reducing overall operational expenses.

However, while adjusting the tonnage of the mine cars, we also need to simultaneously consider the configuration of the buckets. Given the increased payload capacity of the 300-ton class mine cars, in order to ensure reasonable loading intervals and prevent excessive waiting times for the cars, it’s necessary to upgrade the bucket capacity to 25 m³. This adjustment in configuration will guarantee a seamless connection between the loading and transportation stages, streamlining the entire mining operation process and ultimately boosting productivity.

(II) Mining Year and Total Lifecycle Cost of Equipment

The length of the mining year is a critical factor influencing equipment selection, as it directly affects the equipment’s total lifecycle costs—covering acquisition costs, maintenance expenses, operational costs, and even the costs associated with equipment upgrades and replacements. For mines with long-term operations—typically defined as those with service lives exceeding 20 years—equipment reliability becomes the primary consideration. In such scenarios, electric wheel trucks have emerged as one of the top choices for mining operations.

Electric-wheeled mine trucks are powered by electricity and offer advantages such as high efficiency, energy savings, and environmental friendliness. Typically, they have a service life of 15 to 20 years, making them well-suited for long-term mining operations. Although the initial investment in electric-wheeled mine trucks is about 30% higher than that of mechanically driven models, their lower maintenance costs over the long term can lead to significant savings—reducing expenses by approximately 50%. This is because electric-wheeled trucks feature a relatively simple design with fewer transmission components, which minimizes the likelihood of mechanical failures. As a result, maintenance costs and downtime are greatly reduced, boosting equipment availability and ensuring continuous production at the mine.

On the contrary, for mines with short-term operations—those having a service life of less than 10 years—the cost-effectiveness of equipment becomes the key factor. In such cases, diesel-powered mechanical-drive mine cars, thanks to their relatively low acquisition costs, can effectively meet production demands within a shorter mining cycle, making them a particularly suitable choice. Opting for these types of mine cars helps avoid resource wastage caused by idle equipment and reduces investment risks.

In the mining production process, production capacity is not static—it often fluctuates due to factors such as market demand, changes in ore grade, and improvements in mining technology. To address these fluctuations and ensure stable mine operations, it is typically necessary to maintain an equipment redundancy of 10% to 20%.

Take a certain mine as an example: In its initial production phase, the annual output was 6 million tons. Based on the then-current production capacity, 12 mining trucks—each rated at 150 tons—were deployed. As mining technologies continued to improve and market demand grew, the mine’s annual output gradually increased to 8 million tons. Fortunately, since the mine had initially planned for some equipment redundancy, it only required adding 3 more trucks to the existing fleet, bringing the total number of trucks up to 15. This adjustment was sufficient to meet the transportation needs following the expanded production capacity. Not only did this ensure the continuity of mining operations, but it also prevented production delays caused by insufficient equipment. At the same time, it helped avoid costly over-allocations due to excess equipment, ultimately striking a dynamic balance between production capacity and equipment deployment. As a result, the mine achieved efficient and stable operations while optimizing resource utilization.

V. Equipment Selection Optimization Under Multi-factor Coupling

(1) Typical Operating Condition Equipment Configuration Plan

In actual mining operations, different ore deposit conditions require equipment configurations tailored to match them. Through the study and analysis of numerous mining cases, we have summarized several typical equipment configuration schemes designed for various operational scenarios. These solutions were developed after thoroughly considering multiple factors, including reserve size, mining depth, bench height, annual production capacity, and more—making them both representative and highly valuable as references in the industry.

For large-scale open-pit iron mines, which boast abundant reserves, relatively shallow mining depths, substantial bench heights, and high annual production volumes, it is essential to equip them with high-tonnage buckets and haul trucks capable of meeting the demands for efficient extraction. Buckets ranging from 15 to 20 tons and haul trucks carrying 200 to 300 tons can help maintain optimal productivity while simultaneously reducing the per-unit cost of mining ore and rock.

The mining conditions for medium-sized underground copper mines are different: they have moderate reserves, are mined at considerable depths, feature relatively low bench heights, and typically yield lower annual production levels. In such scenarios, 3-to-5-ton buckets and 40-to-60-ton mine cars are better suited for the confined underground working spaces, allowing for flexible loading and transportation operations.

Precious metal open-pit mines have relatively small reserves, shallow mining depths, moderately sized bench heights, and modest annual production levels. 5- to 8-ton buckets and 60- to 100-ton mine trucks can effectively balance thorough resource recovery with controlled equipment investment costs, ultimately maximizing economic efficiency.

(II) Application of Digital Selection Tools

As technology continues to advance, digital selection tools are playing an increasingly important role in the selection of mining equipment. Discrete-event simulation software, such as AnyLogic, provides robust technical support for optimizing mine transportation systems. By building a model of the mine transportation system, we can input data such as ore reserve distribution, bench parameters, and equipment performance curves into the software, enabling simulations that assess material handling efficiency under various tonnage combinations.

Taking a certain mine as an example, when optimizing equipment selection, the transportation system was modeled using AnyLogic software. During the simulation, detailed geological data of the mine were first inputted, including reserve distribution, ore body geometry, and mining depth, among other factors. Simultaneously, performance parameters of different models of buckets and haul trucks—such as bucket capacity, digging force, truck payload, travel speed, and hill-climbing capability—were also entered into the model. By simulating material handling efficiency under various tonnage combinations, it was found that increasing the bucket capacity from 10 tons to 15 tons and raising the haul truck capacity from 100 tons to 180 tons resulted in a 22% increase in system productivity, while energy consumption rose by only 15%. These findings confirm the potential for optimizing equipment tonnage matching, providing a scientific basis for equipment selection in mining operations.

Determining the tonnage of mine cars and buckets is not a straightforward decision-making process—it’s a multi-objective optimization challenge. In this process, it’s essential to comprehensively consider multiple factors, such as geological conditions, equipment performance, and engineering economics, to strike the optimal balance among them. By establishing a coupled model that integrates reserves, depth, bench design, and production capacity, combined with digital simulation technology, we can more accurately analyze the intricate relationships among these factors, enabling precise and intelligent equipment selection.