An Integer Programming Model for Optimisation of a Heavy Media Coal Preparation Plant

摘要

This paper discusses the implementation of a mixed integer linear programming model for a coal preparation plant. The plant considered consists of primary and secondary heavy media cyclones, hydrocyclones for intermediate fi nes and froth fl otation for the very fi ne material. The model is designed to optimise the plant settings and product fl ows to maximise revenues for a given specifi cation for two product outputs. The model can deal with bonus/penalty aspects of the product pricing for products that exceed or fail to meet specifi cation. We report on a model with two separate coal feeds with parallel circuits for the oversize, intermediate and fi nes streams. The genesis of this model is more than 30 years old but recent improvements in mixed integer programming solvers make a full mixed integer formulation practical. The original model began as an enumeration of cut points with arbitrary rules for product allocation. The product allocation was improved in a linear programming formulation by Gunn (1982) and Sarker (1991 and 1995). Current mixed integer programming capabilities make it possible to replace the enumeration aspects and solve directly as a mixed integer programming problem. The current implementation uses a general purpose modelling language to formulate the model. Open source and commercial mixed integer programming solvers are compared.