Load-haul-dump (LHD) machines are powered by diesel, electric, battery, or hybrid systems. Diesel LHDs are efficient but produce noise and emissions. Trolley electric lines or cables are impractical for LHDs, while batteries offer high flexibility during operations but require frequent recharging. Despite the advantages of battery LHDs, studies are limited. This study used discrete event simulation to evaluate the performance of battery LHDs focusing on battery swapping stations and energy consumption in traditional and fork production layouts in a sublevel caving mine. The results showed the battery machines are more energy-efficient when working in a traditional layout than a fork layout. The daily energy consumption is 0.64% less in a traditional layout than a fork layout. The results also showed the selected battery swapping stations are optimal because productivity is not significantly affected by changing the swapping locations.

Diesel-powered load haul dump machines have been the backbone of underground mining loading and hauling operations for over six decades. However, as mines get deeper, and regulations become more rigorous, the adoption of battery electric vehicles (BEVs) has the potential to enhance energy efficiency and provide a healthier environment for miners. Electric engines have a significantly higher energy efficiency and produce no exhaust gases or diesel particulate matter. The use of BEVs in underground operations introduces additional factors to consider, such as battery swapping and the required number of batteries, swapping, and charging stations. This study conducted a discrete event simulation using Arena simulation software with a focus on queueing and its relationship to different numbers of machines, batteries, and swapping times in an underground block cave mine. The results suggest that when there are six, eight, or 12 LHDs and four swapping and charging stations with an unlimited number of batteries, the queueing time to swap the batteries remains minimal. In scenarios with eight LHDs and a limited number of batteries, depending on the battery swapping time, 2–2.5 batteries per machine are required to achieve maximum production with minimal queueing. However, when there are too few batteries, queueing becomes significant. Moreover, when the number of working groups (machines going for a battery swap around the same time) is less than the ratio between the battery operational time and the swapping time, the queueing remains low. 

Ore passes play a vital role in underground mining operations by facilitating the gravity-driven movement of ore from production levels to lower levels. Failure of the ore pass has serious consequences, including possible production disruptions and substantial financial investments in reconstruction or rehabilitation. Failure mechanisms are often associated with rock mass quality, stress conditions, and wear of the ore pass walls. This study investigated the degradation of ore pass walls using scanning data at LKAB’s Kiirunavaara mine in Sweden. Geotechnical information obtained from various sources aided in further understanding the ore passes’ conditions. The study revealed variations in the ore pass growth rates, highlighting potential stability concerns and the correlation between throughput and pass growth. The findings underscore the need for continuous monitoring and regular inspection to manage wall degradation. The paper proposes potential rehabilitation measures to ensure the stability and safety of ore passes in mining operations.

Ore passes are often the main part of sublevel caving transportation systems, and they use gravity to move material to lower levels in the mine. During operations, the ore pass structures are exposed to the risk of stoppage and failure, leading to a long-term reduction in operational capacity and affecting productivity. The failed ore passes can be restored or rehabilitated, but the rehabilitation cost is normally high and the time to restore is usually long. To minimize disturbances and stoppage of the ore pass, alternative strategies should be considered. The appropriate design and operation of an ore pass is crucial. Therefore, this study compared running ore pass systems in a filled, near-empty, or flow-through manner using discrete event simulation. The aim was to compare the ore pass operational performance and impact on reaching the daily and 90-day production targets of 76.4 Ktonnes and 6.9 Mtonnes, respectively. The results showed that running the ore pass in flow-through mode, filled manner, and near-empty manner achieved 96%, 80%, and 81% of the production target, respectively. In mining operations where ore pass systems are used to transfer material, running them in a flow-through mode can ensure higher production and fewer hang-ups, as it lessens the chance of blocks arching over a chute throat and leads to less blasting.

In underground mining environment where the loss of orepasses is a dominant factor, the mine may face a challenge of improving the loading and hauling operations. Some of the options will be to rehabilitate the lost orepasses, or developing the new ones. When the rehabilitation cost is high, alternative strategies should be applied to compensate for the orepasses failure. One of the possible options is to use diesel or electric Load-Haul-Dumps (LHDs). The use of diesel-powered LHDs will increase heat and gas emissions which increase environmental concerns and ventilation costs, while adoption of electric-powered vehicles needs to be analysed. Therefore, this study was conducted at an existing underground mine in Sweden, to determine the electricity consumption and costs of electric-powered LHDs when there is a loss of orepasses. The AutoModTM discrete event simulation tool was used during the analysis. The results show that, electric-powered LHDs have significant cost saving when used in case of orepass loss to move materials compared to diesel-powered units. However, the source of electricity to fully adopt electric-powered units may need further financial justifications to evaluate the impacts to the environment.

Today's mining operations require fast reporting and rapid rescheduling based on updated information. An automatic mine scheduling system could not only quickly reschedule but also propose alternative solutions. To avoid the financial and physical risks associated with testing such a system directly in operation, it could be first evaluated via discrete event simulation models. This would offer a safe environment to evaluate different operating rules and algorithms. In this study, this is achieved by integrating automatic scheduling software with a discrete event simulation model.

The research presented in this thesis addresses several aspects of loading operations inunderground mines, in particular tools and equipment selection. It also addresses the flexibilityof the fleet when subject to substantial disturbances, such as ore pass loss, and proposes integration of the scheduling system with discrete event simulation. The thesis begins with a study of discrete event simulation (DES) tools for loading operations in an underground mining system. The results show the benefits of using simulation but also the drawbacks.The thesis presents an analysis of energy consumption and exhaust gas emissions from diesel and electric LHDs. The results show the potential energy savings with the use of electric LHDs. Next, it focuses on the LHD operations affected by long-term ore pass loss (unavailability). It shows the effects on the production system (the ventilation requirements, production and waiting times when too many LHDs operate in the area affected by an ore pass loss) and highlights the need for a flexible solution and a mitigation strategy. Finally, the thesis studies the integration of ABB’s Ability Operations Management System (OMS) with the SimMine simulation model and how this affects LHD operations. The results show the benefits of using the joined platformas a testbed and decision support system.

Load-haul-dump machines (LHDs) are typically used in underground metal mining opera-tions. Delays or inappropriate use of LHDs can result in production loss. Optimized LHD use is especially crucial in larger mines because longer travel distances increase heat, dust, and gas emissions, which in turn increase ventilation costs. This study, conducted at an existing Swedish sublevel cave underground mine, used discrete event simulation and the AutoMod™ DES tool to determine the ventilation costs related to using too many diesel LHDs in a production area with reduced ore pass availability. When fewer ore passes are available, ventilation costs related to operating LHDs in the production area were found to increase by as much as 200, 224, and 306% for one, three, and six LHDs in operation, respectively.  

Orepass failure is a well-known problem in deep mines, and the risk of losing an orepass is associated with severe production disturbances. In the near future, one possible scenario in the Loussavaara Kiirunavaara Aktiebolag (LKAB) Malmberget mine is to concentrate the mining operation in fewer, but larger, production areas. In this paper we evaluate the effects of orepass loss on loading, hauling, and dumping operations and production rates using discrete event simulation, by simulating part of the Malmberget mine loading and hauling system under different environmental and operational constraints.