A perfect mine truck fleet requires a sound knowledge of a number of concepts. For instance, the truck class refers to a truck’s engine size and cargo capacity, whereas tyre size defines the size of the load footprint of that particular truck. On the other hand, the haul profile includes distance covered, cycle duration, and route taken. Road geometry entails longitudinal grade and rolling resistance, and payload is defined as the maximum cargo load a truck can carry.
Truck class depends on the payload capacity requirement of a mine. An effective haul system seeks to achieve set production goals without wasting too much fuel. Selecting an optimum number of trucks ensures that loading equipment is never idle when a truck becomes available, and it also eliminates truck congestion and dumping site queues (Huayanca et al., 2023). Dynamic fleet assessment plays a critical role in maintaining productive earthwork activities without compromising profitability (Khallaf et al., 2024).
The haul cycle forms the bedrock upon which scaling and equipment selection is done. Where haul cycles are short, with several stops along the way, the use of many small class trucks ensures fast and continuous loading. In case of long haul distances, it is advisable to employ ultra-class trucks because these can carry maximum payloads per movement. The examination of the times taken when the trucks are laden or unladen during a particular haul cycle determines the number of vehicles needed to meet continuous transport needs (Anani et al., 2022).
Geometric characteristics of the road play a crucial role in ensuring efficient performance and durability of the truck. Hauling trucks must have adequate rim pull and power depending on the degree of gradients and rolling resistance. High gradients demand high power and retarding capacity trucks. Inadequate geometric characteristics lead to energy loss and increased rate of wear of the truck parts and tires.
The choice of tyres is always relative to the particular truck category, the road geometry, and the loading that will be undertaken. The tyres should be able to carry the total gross weight of the vehicles and be capable of safely discharging heat produced during operation. The TKPH value for a tyre is always required to be greater than the loading and speeds required at the operation to avoid serious tyre blowout problems. Higher levels of rolling resistance caused by poor maintenance of the roads exacerbate both these factors.
Truck categories and tyre sizes are always interdependent decisions. Mining engineers have to balance the maximum payload potential, the road geometry limitations, and the exact times that will be involved in the hauling cycle. Proper balancing of all these factors allows the open pit mine to achieve efficient haulage and increase their productivity.
References
Anani, A., Nyaaba, W., & Cordova, E. (2022). An integrated approach to panel width, fleet size, and change-out time optimization in room-and-pillar mines. Journal of the Southern African Institute of Mining and Metallurgy, 122(4). https://doi.org/10.17159/2411-9717/1509/2022
Huayanca, D., Bujaico, G., & Delgado, A. (2023). Application of Discrete-Event Simulation for Truck Fleet Estimation at an Open-Pit Copper Mine in Peru. Applied Sciences, 13(7), 4093. https://doi.org/10.3390/app13074093
Khallaf, Z., Alshibani, A., Alsawafy, O., Mohammed, A., & Bubshait, A. (2024). Dynamic Fleet Configuration Model for Optimizing Earthmoving Operations Using Mixed Integer Linear Programming. Journal of Construction Engineering and Management, 150(11). https://doi.org/10.1061/jcemd4.coeng-14817
