Simulation of open pit excavator-truck haulage system - a case study at Golden Star Wassa Limited

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.