| This research deals with very short term production plan and truck-shovel hauling system in open pit mines. The main shortcomings of the existing models reviewed in the literature are: a) not considering the waiting time and queue at servers (shovels and crushers), b) simplifying the models and considering a limited amount of details in the models, c) ignoring the stochastic nature of the truck and shovel hauling system, d) developing model based on an homogeneous fleet (trucks and shovels).;The objectives of this research are: 1- to develop and apply a basic simulation model considering the queue and waiting time of trucks at shovels and crushers in both deterministic and stochastic situations based on the linear programming (LP) model result. This model validates the result of the LP model and provides the detailed and applicable dispatching plan for an open pit mine, 2- To develop, apply and verify the second simulation model which is the real time control system. This simulation model maximizes the ore production while taking into account the LP constraints. This model imitates the truck shovel haulage system in both deterministic and stochastic situations.;The proposed models are applied in a coal open pit mine. The obtained results from the LP and simulation models in our case study demonstrate the fact that the crusher is the bottleneck of the system. Then, in order to validate and verify the proposed models, we created two other scenarios where the fleet of trucks and the shovel's service time are considered respectively as bottleneck of the operational system.;When the fleet of trucks is the bottleneck, the result of the LP model is too optimistic and differs from the reality. The LP model does not consider the waiting time at servers while the basic simulation model takes into account the queue at crushers and shovels. As a result, as soon as the waiting time occurs in the simulation model, system is losing time thus the production of ore is lower than the expected. The real time simulation model has better results than the basic simulation model. The reason is that in the second simulation model, the waiting time at shovels will be penalized therefore; this model has a better production level than the basic simulation model.;When the shovel loading time is considered as the bottleneck of the system, the result of the second simulation model produces more waste in comparison with LP model solution. Since in the LP model, the objective is to maximize the ore production only, there are an infinite number of solutions which have the same level of ore production but different amounts of extracted waste. |
