Abstract

There are many potential advantages to be gained from using battery electric vehicles (BeV) in the place of diesel-powered equipment on mine sites. In addition to a decrease in diesel consumption and Greenhouse Gas (GHG) emissions, BeV’s can also provide productivity improvements through higher breakout forces and low speed torque.  Substantial capital costs and power requirements for ventilation can often be reduced to improve the viability of new developments.  For mine expansions, electrification can mean limited or no upgrades to existing ventilation systems or provide a way of maintaining compliance with changing NO² thresholds. Regenerative breaking capabilities of battery electric vehicles can also reduce overall power consumption and reduce braking heat loads and refrigeration costs for deep mining operations. Maintenance requirements can also be significantly less for electric equipment, resulting in availability improvements.

Available options for sourcing electric power for the mine site and standardization of electrical equipment can be shortcomings for electrification.  However, the biggest problem with battery electric equipment is typically battery energy density and associated range limitations. Battery range depends on the site-specific duty requirements. Range limitations are a particular issue for uphill haulage, where a Battery Electric Haul Truck (BEHT) using today's technology might achieve anywhere from 2-3 cycles down to less than a single full cycle for particularly long hauls.  This presents a significantly different operation to an equivalent diesel-powered haul truck that would usually complete a full shift of 10+ cycles before needing refueling.  When the battery range is of a similar order to the average haulage cycle, battery state becomes a central consideration for equipment dispatch.

Dispatch for diesel equipment needs to take the congestion and queuing implications for available routing options into consideration. BEHT dispatch also needs to consider whether the truck has sufficient range to reach the loading point, haul the material to the designated destination and return to a charging or battery swap location. Careful planning of future haul cycles will be required on some sites to make good use of the available battery range. Real-time dispatch optimization is also likely to be required to maximise the use of the available battery range. Decision making complexity can be further compounded when mobile equipment is capable of regenerative braking and/or when trolley assist is available for parts of the mine network.

This presentation covers the use of simulation models with comprehensive BeV dispatch logic to quantify the usable battery range when routing options are constrained by the operational complexity of the overall mining system. Dispatch engines used in the simulation model include calculation of energy costs for routing options to determine feasible routing decisions and ensure that BeV’s can return to charging locations. Simulation analysis is used to determine the useable proportion of total battery range for BeV’s, the impacts of range constraints on dispatch decisions and resulting performance of the mining operation. The simulation model is also used to test relative performances improvements for BeV dispatch optimisation.