Abstract:
The focus of this research work was to employ simulation technique in optimising excavator truck haulage system in the open pit mining operations at Golden Star Wassa Limited
(GSWL). Discrete Event Simulation (DES) was used to determine the achievable
productivity of the excavators involved in loading of trucks, determine the optimal truck fleet
size to match the two excavators utilised, and determine measures to improve truck and
excavator productivity to reduce the overall mining cost. Field visits for data collection on
time and motion studies were conducted, statistical analysis of the data was performed using
ARENA input analyser (statistical tool). A simulation model of the excavator-truck haulage
system was run using ARENA software and the results were statistically analysed. The DES
model was designed with the optimum number of trucks for the haulage system, average
monthly production, waiting time of trucks (in minutes) and the queue length as the
performance indices. Simulation results gave eight (8) trucks as the optimal truck fleet size
instead of the current fleet of 11 trucks. The optimum fleet of 8 trucks will give an achievable
production of 599 129 t per month. A dispatch logic considering minimum truck queue length
at excavator was simulated as a way testing its effect on the production. Results showed that
with the dispatch logic employed, ore tonnes mined increased by 6% compared to simulated
result without the dispatching logic.
