With the latest advances in battery technology, fast charging capabilities, and other technologies such as regenerative braking and more efficient battery electric systems, the use of Battery Electric Vehicles (BEV) in the mining industry is becoming more advantageous. In 2019, SRK Consulting conducted a BEV study for a mine in South America. The purpose of this study was to consider an alternative ventilation system design for a previously completed study in which an all-diesel fleet was planned. For this study, the client requested that only the haul trucks and load-haul-dump loaders (LHD) be considered for conversion from diesel to battery electric. All other equipment would be left as diesel as in the previous study. The results of the study showed significant reductions in ventilation system infrastructure requirements if using battery electric equipment rather than with equivalent diesel-powered equipment.
When designing a ventilation system, the typical starting point for determining a basic minimum airflow requirement for a mine is to use the project's local regulatory agency’s values specified for diesel engines and for pollutants generated from combustion. By considering an entire mine’s diesel equipment fleet; determining total minimum mine airflows and localized, zone specific, airflows are generally straightforward using this method. Other considerations such as for heat and dust are often mitigated within the relatively high airflow demands required for diesel equipment.
For this study, the use of BEVs for the primary haulage and loading equipment significantly reduced the airflow needed to dilute diesel exhaust. Secondary and maintenance diesel equipment still contributed to the determination of the airflow requirement; however, other considerations for heat, dust, and minimum air velocities needed to be considered more closely. Based on these considerations several ventilation models and thermal models were developed at key ventilation stages in the mine life to assess ventilation demands and potential savings.
The analysis exposed several opportunities by using the BEVs. The results of the study showed that the ventilation system airflow demand could potentially be reduced by 50% of the original airflow if the proposed BEV strategy was utilized and a potential reduction of the total fan power by approximately 80%. This did not involve making any modifications to the original mine infrastructure other than redistributing the required airflow in the mine to meet various mining demands. Several options were also considered to reduce development costs. With less airflow demand, the size and number of raises could be reduced resulting in significant development cost savings. By reducing the size and number of raises underground, the study showed that the total volume removed by raise/shafts could be reduced by more than 50%. Even when considering the raise/shafts size reduction which results in a higher overall mine resistance, a main fan power savings of up to 60% was calculated.
With recent advances in BEV technology, significant benefits and savings for mine ventilation systems may be possible. To date, only a small number of mines have started to employ significant use of BEVs so limited data is available for actual savings. For significant implementation of BEVs to occur, challenges such as battery degradation, potential production losses due to charging and/or battery swap outs, power grid requirements for charging of batteries etc. may need to be more thoroughly analyzed. Despite these potential issues, a more significant use of BEVs provides a promising alternative which may save significantly on power costs and result in cleaner air in mining environments.
Related Video: Mine Ventilation Design Implications of Battery-Electric Equipment
