Potential economic and operational benefits and impacts of trolley assist in open pit mining

In a diesel-electric haul truck, a diesel engine is used to drive an alternator that produces the energy required to power electric wheel motors. Trolley Assist (“TA”) allows a diesel-electric haul truck to bypass the diesel engine entirely when in TA mode so that electric power can be supplied directly by overhead lines. The result is an increase of approximately 10km/hr. in loaded up-ramp travel speed, as well as the substitution of diesel fuel with cheaper and cleaner electrical energy. This improved grade performance can have a significant impact on truck productivity, personnel requirements, fuel consumption, and operating and capital costs.

Although TA systems have been available for over 40 years and despite interesting operational and environmental benefits (reduced CO₂, NOx, noise emissions, etc.), few operations have employed them. The decision to install a TA system is heavily dependent on the size and overall mine plan of an operation. Additionally, these systems involve significant capital investments and require technical expertise to efficiently design, plan and maintain them.

This paper will analyze some of the economic, operational and planning implications and benefits of installing TA at large open-pit operations in Canada based on studies completed by BBA.

Note that this white paper was written in collaboration with Daniel Janusauskas from Detour Gold Corporation. It was presented at the Maintenance, Engineering and Reliability/ Mine Operators (MEMO) Conference in September 2014.