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In the OCP phosphate supply chain, source ores (SOs) are extracted according to a tactical extraction programme, constrained by geological conditions that constantly limit and modify the variety of available SOs. Then SOs are blended to get merchantable ores (MOs) respecting composition constraints and ordered by internal (phosphoric acid plant) or external (export) customers. The blending process is performed in a dry blending plant, possibly followed by treatments in a washing plant which modifies the SOs weights and compositions. The choice of alternative routings and blends depends on orders book and SOs availability in the dry blending area or present on mine. To improve the performance in meeting a rolling 4-weeks orders book, a quadratic model was created and implemented. It optimises jointly: (i) for each order, the routing and the SOs quantities used in the dry blending plant; (ii) the SOs quantities transferred from the mine; (iii) security stocks to face some unforeseen change in the MO book order, and the slight instability of the SO chemical composition that triggers a SO multiplication to be contained. The performance of the linearised model has led the relevant OCP site to develop and use an extended version of this model.

Open-pit phosphate mine is characterized by a stack of layers with different chemical characteristics (Source qualities SQ). The extraction process involves various elementary operations performed by a dedicated or polyvalent machines. The tactical mining scheduling consists to define the blocs to be extracted and assign the machines over the planning horizon. However, the interdependencies and complexity characterizing this problem make the decision-making process so difficult. This paper proposes a multi-criteria approach integrated in an Interactive Decision Support System (IDSS) based on an original sequential approach selecting the most performant mining scenarios. Indeed, a discrete event simulation-based model developed and encapsulated in this IDSS proposes various scenarios. With a developed multi-criteria filtering approach, each scenario is approved by a feasibility study to verify that a scenario can satisfy the demand for merchantable qualities (MQ). Then, the feasible scenarios are analyzed based on their robustness when facing disturbed demand vectors and compared by other effectiveness and efficiency criteria. To preserve only the two or three most performant scenarios.

International audience; as open-pit mines consist in the accumulation of ore layers of different characteristics, their extraction process results from the iteration of a sequence of elementary operations performed on parcels by specialized or multipurpose machines. Medium-term extraction programming consists in deciding the assignment of the available machines over time. This problem is addressed through Discrete Event Simulation implemented in a phosphate mine, taking into account all the extraction constraints to drive the extraction process. This combines an effectiveness criterion (degree of urgency of obtaining certain ore qualities) and an efficiency criterion (machine displacements). While the parameterization used to control simulation quickly produces many technically feasible scenarios, making the final optimal choice is extremely difficult, particularly as one needs to take into account time considerations in extracted ore progressive provisioning and machine use. Our paper describes the bases of a visual decision-support system (DSS), currently under development, which enables the processing of results to compare multiple scenarios and adjust parameterization in order to come up with a good solution. This web-based DSS is coupled to the simulator via a relational database.

This paper presents the architecture of an interactive scheduling decision support system (ISDSS) allowing users to find the optimal solution for fertilizer production on parallel heterogeneous processors. The proposed approach takes into account different production process constraints such as launch time, delivery date, preventive maintenance and the impact of scheduling on supply chain management. The ISDSS implemented is run by a relational database used to customize the structural data and the problem parameters. A user interface is available for ISDSS users to define the scheduling problem and design the solution based on tables and graphs for detecting possible issues. The ISDSS architecture was implemented on java using independent modules.

Open-pit deposits are often characterised by a stack of layers of different geological nature. Some layers are worthless while the ore of the others is of a varying economic value depending on grade. To reach a layer, it is necessary to have first removed the upper layers above the extraction zone. This action results in uncovering the layer in this particular place and in facilitating access to the layers below. This extraction process involves a series of 2–7 basic operations; each one is performed by a machine, some of which are able to perform up to three different operations. Ensuring the consistency of mining extraction scheduling over a few months, in order to meet known or forecast demand, is a challenging task. A mining extraction model based on mathematical programming is proposed but it is hardly usable, due to its size. Therefore, a model based on a Discrete Event Simulation, is created to test how ore supplies are affected by the tactical and operational decisions relating to the choice of parcels to be processed and to the allocation of machines to the different basic operations