Extractives: Battery-Electric Mobile Plant in Mining and Quarrying
What this domain tests
The Extractives domain tests battery-electric load-haul-dump (LHD) units, drills and quarry plant. It focuses on underground ventilation, charging-bay design, heat load, lithium-ion thermal runaway, gas monitoring and HV maintenance. The exam expects you to compare diesel and electric hazards rather than assume electric is hazard-free.
Core rules and concepts
- Battery-electric plant removes diesel particulate matter and NOx at the point of use, but adds electrical, thermal and battery off-gas hazards.
- Ventilation design must remove motor and charger heat and any battery thermal-runaway gases. A 150 kW motor at 90% efficiency releases about 15 kW of heat into the airway.
- Lithium-ion thermal runaway can produce carbon monoxide, hydrogen, hydrogen fluoride and flammable electrolyte vapour. Gas detection and emergency response planning are required.
- Charging bays need dedicated ventilation, fire suppression, isolation, barricades and a no-hot-work rule.
- HV maintenance follows isolation, prove-dead, discharge and PPE rules; water and dust ingress ratings must suit the mine environment.
Worked example
An LHD has a 200 kWh pack and works to 80% depth of discharge: 200 × 0.80 = 160 kWh to replace. A 60 kW charger with 90% efficiency and average taper delivers about 50 kW, so charge time is 160 ÷ 50 = 3.2 hours. An 8-hour shift needs an opportunity charge at the break, not a single end-of-shift charge. The charger losses, about 6 kW, also heat the charging bay, so ventilation cannot be sized for the vehicle motor alone.
Traps that cost marks
Assuming an electric mine needs no ventilation; ignoring charger heat; treating battery off-gas as harmless; applying water to a lithium-ion fire without the site emergency response team; failing to barricade a smoking pack; and not isolating HV before maintenance.