Electrification plays a significant role in achieving net zero targets, and existing underground mines are required to reach deeper depths to meet the increasing demand for rare earths and metals. Traditionally, underground mining loading and hauling operations have been performed using diesel-powered load haul dump (LHD) machines and trucks. These machines are powered by internal combustion engines (ICEs) that emit exhaust gases, diesel particulate matter (DPM), and heat. Battery electric vehicles (BEVs), powered by electric engine, were introduced in underground mining in the early 2010s. Electric engines enable higher energy efficiency than ICEs and do not produce exhaust. Therefore, they have the potential to facilitate cleaner air and reduce ventilation demand, thus reducing costs.

Although BEVs have been used for more than a decade in underground mining, there is limited research on user and mine experiences or operational aspects. Simulation studies comparing BEVs and diesel machines using different loading and hauling strategies and quantifying productivity differences have not yet been extensively conducted, particularly in the context of battery swapping. This thesis investigates how employing BEVs in current underground mine loading and hauling practices affects the mining operations. The research carried two exploratory surveys, targeting underground mine personnel and mine management, to obtain their points of view on BEVs and their experiences using them in underground mining. In addition, a discrete event simulation (DES) model was developed to compare and analyse the battery swapping and fleet dimensioning of LHDs in the case study block cave mine.

The survey findings show the main motivators for underground mine management to employ BEVs within their operations were to make the working environment healthier and reduce carbon emissions. The identified hindering factors were related to high costs and lack of proven reliability. Mine personnel appreciated that the BEVs were quieter, had fewer components and fluids, and improved the air quality. However, they had concerns related to fire risk, limited battery duration, and work performance. According to the DES simulation results, speed and hauling strategy have a significant impact on productivity. BEVs with equivalent gear can achieve, on average, between 6.5% and 10.3% higher productivity than equivalent diesel machines. The queueing at the swapping station appears to remain low even with a maximum number of machines and maximum battery swapping time when there are sufficient batteries within the system. The LHDs were able to reach maximal production with minimal queueing with 2-2.5 batteries per machine. Future studies should focus on analysing operational aspects and the brought value when using BEVs in loading and hauling operations. These aspects could include quantifying the impact on ventilation using field measurements, assessing the power differences of different types of LHDs, and analysing differences between different types of loading and hauling machinery from the specification perspective.

Electrification is one of the enablers to achieve future net-zero targets. With current battery technology, as close-to-surface deposits are depleted, the need for metals and rare earths is pushing underground mines deeper into the Earth’s crust.

Underground mines have traditionally relied on diesel-powered load-haul-dump (LHD) machines in their loading and hauling operations. These machines are powered by internal combustion engines (ICEs) that emit exhaust gases, diesel particulate matter (DPM), and heat. Battery powered LHDs have been used in underground mining since the early 2010s, with Canada the earliest adopter of this technology. Battery electric vehicles (BEVs) use electric engines that enable higher energy efficiency than ICEs and do not produce exhaust. Therefore, they have the potential to facilitate cleaner air and reduce ventilation demand, thus reducing costs.

This research investigated and analysed how the implementation of battery electric (BE) LHD machines affects current underground mine loading and hauling practices and operations. When BEVs are used instead of diesel LHDs, they bring with them additional aspects that are crucial to explore, such as the perception of the personnel and how BEV LHDs differ from a productivity perspective, specifically when using battery swapping. Furthermore, when changing the machine type from diesel to BEVs, it is important to know what differences this will make to the required ventilation and air conditioning demands, as these have traditionally been established based on the number of diesel machines in the underground mine and their engine power.

This research was initiated by exploring the points of view and perspectives of underground mining personnel and management and analysing how these perspectives differed. Then, productivity and operational studies were conducted using two case study mines: a block cave mine and a sublevel caving (SLC) mine. The research investigated alternative configurations of LHDs for optimised productivity and identified queues and the required number of extra batteries for BEV operations using discrete event simulation (DES). Subsequently, field measurements were conducted in the case study SLC mine to quantify the potential reduction in the ventilation requirements, as ventilation-related energy consumption can result in half of the mine operation’s energy use. Finally, diesel, electric, and BEV LHDs were compared based on machine specifications.

The results suggest that independent of their experience with BEVs, the management chose the same three primary reasons to use BEVs: they wanted to make the working environment healthier, reduce carbon emissions, and reduce air conditioning and ventilation-related costs. The main reasons why mines were not considering BEVs in their future operations were related to their high price and being unproven. Independent of their experience of working with BEVs, the underground mine personnel liked them because of their quietness, spacious cabins or modernity, and absence of exhaust fumes; however, they shared concerns specifically related to safety and fire risk aspects.

According to the DES simulation results, BEV LHDs can achieve, on average, 8.9-12.1% higher productivity with a loop hauling strategy than with direct hauling in an equivalent gear. Additionally, the BEV LHDs achieved, on average, 6.5-10.3% higher productivity than diesel LHDs in equivalent scenarios. In terms of queueing, when there were enough batteries in the system, the BEV LHD queueing did not accumulate when there was a maximum of 12 LHDs with four charging stations and a maximum battery swap of one hour because “working groups” were formed. Eight BEV LHDs using from 16 to 20 batteries (2-2.5 batteries/LHD) reached minimal queueing. Field measurement results showed the potential to reduce airflow by at least 70-77% in the studied area of the case study SLC mine. Finally, a comparison of power types showed no significant differences between them in terms of maximum (rimpull) force, standard bucket size, breakout force (tilt and lift), operational (empty) weight, and tramming capacity.