Integrated tactical continuous production planning of two blending systems sharing supply sources: the case of a phosphate supply chain
The tightening of product quality requirements by customers on merchantable phosphate ores (MOs) prevents the world's largest phosphate production site from continuing to plan its production with the current rules. This paper deals with a problem of tactical planning of production activities and considers the case of a phosphate SC covering hundreds of km2, with several mines, several washing plants, and a drying plant, with transport of MOs by rail or pipeline. MOs are obtained by blending ores (SOs) of varying compositions and volumes. Currently, the plants are managed quite independently, SOs are pre-assigned to the MOs, and the MO production routings in the washing plants are predetermined. We propose a model that ensures flexibility in the production of MOs through the choice of dynamic blends and routings. Our approach goes beyond any pre-allocation of resources and aims at synchronising the flows of the washing plants. This specific problem of blending production and planning has not been addressed in the scientific literature. Still, it is widely encountered in many mining industries and offers perspectives for the application of the approach proposed in this paper. Numerous tests show that this model makes it possible to respect the quality constraints related to the composition of several chemical components, with a generalised use of the most economical routings while ensuring horizontal and vertical alignment of decisions.