⎪ Heating, cooling, ventilation and air conditioning ⎪
so a dedicated charging station is needed underground. This requires additional electri- cal infrastructure with sufficient capacity to charge multiple vehicles simultaneously at the end of each shift. “Additional batteries are also an option, which can speed up the turnaround time for charging a vehicle and reduce the number of EVs required. Either way, charging an EV is not nearly as quick as filling a diesel fuel tank. And while charging is getting faster, the faster the charge, the higher the heat rejection, which becomes a capacity factor for the ventilation system. The whole charging station has to be ventilated with careful consideration given to airflow management and exhaust air han - dling,” he says. The potential risk associated with an EV battery fire must also be taken into account. Battery management systems monitor temperature and actively control charging rates to prevent overheating. A lot of time and effort has been put into these systems to prevent uncontrollable thermal runaway, which can occur if battery cells become criti- cally overheated. Once thermal runaway starts, however, it is extremely difficult to stop. “This causes a very high fire safety risk that has to be mitigated in underground EV battery charg- ing stations. In the event of a battery fire at a
charging station, measures such as dedicated exhaust routes, compartmentalisation, sup- pression systems, or other emergency ventila- tion strategies are needed to prevent smoke and harmful gases from endangering miners. “The large numbers of possibilities in- volved in mitigating these risks create engi- neering and infrastructure challenges, which all need to be factored into any evaluation of EV technology,” Russell Hattingh points out. BBE transition evaluations “What often drives these developments is legislation relating to DPM and NOx expo- sure, for example, and the drive to reduce these exposures is already underway in South Africa. The use of EVs has the potential to reduce many of these concerns. As a result, mine operators are working closely with OEMs to develop practical electric vehicle and battery charging solutions suited to the mining environment, to reduce significantly or potentially eliminate DPM and NOx expo- sure,” he continues. In terms of direct operating costs, EVs are known to be more energy-efficient and generate less heat in the mine environment than diesel trucks and LHDs, so that long-term savings can be significant. “Saving comes at a cost, though, largely in terms of the infrastructure changes required
and the capital investment in the EV fleet and the long-term cost equations obviously need to be favourable. Ultimately, Hattingh believes that in time, this transition will definitely happen in some mines. Reducing exposure to mining person- nel makes the underground environment safer and more comfortable. In addition, EVs can significantly reduce refrigeration demand compared with diesel fleets. However, the reduction in ventilation demand is often less pronounced because minimum air velocity requirements often govern airflow under- ground. As a result, the overall benefit de - pends strongly on the mining method. “This is particularly relevant in mechanised mining en- vironments using large fleets of underground vehicles, typically where mining methods are used to mine thick ore body deposits. “The benefit depends on many, many aspects, though, the mining method, how big the existing fleet is, dust loading, whether it's a greenfield or brownfield project, and much more. “So, as one has to do with any displacement technology, we need to do our homework to see if it's worthwhile: in terms of cost benefits, miner safety, legislation, the environment and long-term mine sustainability,” concludes Russell Hattingh. https://bbegroup.com/
May-June 2026 • MechChem Africa ¦ 33
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