Abstract:
The aim of this research was to develop a simulation model of the shovel – truck systems
and investigate the various scenarios of the shovel – truck models. The investigation will
determine the achievable production with an optimal number of trucks at Ghana Manganese
Company Limited (GMC). Data for this research was acquired by conducting time and
motion studies, regular field visits and statistical analysis of the data was performed using
ARENA input analyser (statistical tool). A simulation model of the shovel – truck system
was developed to mimic GMC shovel – truck system and ran using ARENA software and
the results were statistically analysed. The Discrete Event Simulation (DES) model was
designed to achieve the optimal loading time and the number of trucks for the operations as
the key performance indicators. Results from the simulation established that the optimal
loading time is 25 % less than the actual loading time of each shovel. The determined
loading times of excavators EX 16, EX17, EX 18 and EX 19 are 2.9 minutes, 3.1 minutes,
3.1 minutes and 2.9 minutes respectively so the overall average loading time in Pit C North
is 3 minutes. The variance between the actual and the total simulated production for the
optimal loading time is 178484 tonnes which represents 5.2 % increase in production when
the optimal loading time is implemented on the mine. The achievable productivity for the
excavators was reached at the optimum truck fleet size of 26 which means the current system
is under-serviced by six (6) trucks. In order to run an optimized truck fleet size, two (2) extra
trucks of capacity 91 tonnes need to be assigned to EX 16, one (1) extra truck of capacity
91 tonnes also needs to be assigned to EX 17, EX 18 will require extra one (1) 140 tonnes
truck and EX 19 will also require two (2) extra trucks of capacity 140 tonnes. The
determined production when the optimal number of trucks (26) is employed is 4,325,932
tonnes which is 27 % more than the actual production achieved by the shovel-truck system
at GMC. This production is at least 3 % more than the monthly deficit in production on the
mine which ranges between 18 % to 24 %.
