linear programming

Since a significant part of mine operating cost belongs to hauling operations, optimizing the allocation and scheduling of trucks in a dynamic system is essential and significantly affects production efficiency. So far, different models and methods have been proposed for optimizing haulage scheduling. In this paper, scheduling models have been reviewed, and a flow-shop model has been developed to optimize truck dispatching systems in open-pit mines. The proposed model has been implemented on a small-scale example, driven by a real-world case study, and results have been discussed. Numerical investigation demonstrates that this model is a powerful tool for optimizing truck scheduling and can result in an enhancement in the productivity of mining operations. The most crucial challenge that must be addressed in future work is the development of fast solution techniques to solve real-scale instances of the developed model.  

The hauling operation is responsible for a significant portion of the operating cost in an open pit mine operation. Therefore, as the main hauling machine, trucks' optimum scheduling is crucial and can dramatically affect mine production productivity. Conventionally, assignment and dispatching of the trucks are defined as two main optimization problems in scheduling hauling operations. Simulation and stepwise mathematical programming have been proposed in the literature to solve these two problems. However, a dynamic and integrated optimization model is required to optimize hauling operations of the state-of-the-art revolution in data collection systems, computational capacity, and the necessity of real-time decision-making. Therefore, this study aims to develop an integrated and single-stage optimization model to optimize truck scheduling problems.

In this study, the truck dispatching problem has been discussed, and a flow-shop scheduling model has been suggested as the best model to be considered for modeling open-pit hauling operations. In a flow shop problem, a set of jobs flow through several stages in the same machine order. The proposed flow shop model has been evaluated using an example from real case study data.  

The results show that job scheduling models for truck optimization can optimize haulage scheduling and truck dispatching in open-pit mines. Using the developed flow shop model, it is possible to incorporate different mining KPI’s such as production time, production productivity, and fuel consumption. This model can also provide a prototype tool for real-time scheduling. Future work is on track to develop fast and reliable metaheuristic solution techniques for this problem's large-scale instances.

Basically, in the chain of the decorative stone industry, the cost of transporting the excavated rock from mine to the rock cutting factories, and then shipping of the processed plate and slab stone to the market places has a major impact on the finished product price. In this research, firstly, each of the decorative stone chain components including mines, rock cutting factories and consumer markets in Iran was divided into 10 main poles. Then, the linear programming model for minimization of total transporting tonnage and distances of raw rock from poles to processing poles and processed slab from mine to trade materials and transferring processed rocks from factories to market poles were defined. The constraints of the model were defined based on the proportion of production capacities in poles throughout the production chain. After solving the model with the GAMS software, the optimal delivery tonnage between the poles as scenario 1 was calculated. Also, two separate scenarios have been defined in terms of 20 percent increase in production capacity of mine poles and 20 percent increase in consumption and processing capacity poles. The second scenario reduces the average shipments per unit product by 3.9 %, but it has no positive impact on the utilization ratio of the production capacity in mine and factory poles. The third scenario improves the utilization rate of the mines poles, however increases the total shipment of the raw material from the mine to the factory by 28%, and also increases the average distance per unit product along the chain by 8.2%. This scenario could lead to increasing the unit production cost and reducing the competitiveness of the final product.