SPECIFICATION FRAMEWORK FOR ROBUST-CONTROL OF A RUN-OF-MINE ORE MILLING CIRCUIT

It is difficult in run-of-mine (ROM) milling circuits to control the particle size of the product and other important variables because the ore fed to the mill also acts as the main grinding medium. This results in significant uncontrolled disturbances and uncertainties. Before the mu-controller synthesis and analysis methodology can be applied to this multivariable control problem it is necessary to formalize the uncertainties and specifications in terms of a suitable general framework. The uncertainty description for an industrial milling circuit obtained from plant perturbation tests is used to motivate the choice and location of uncertainty weights within the plant transfer function matrix structure. The choice of performance weights based on their economic and plant-related importance is also discussed. The ROM milling circuit model with its uncertainty and performance weights is then cast into a general synthesis and analysis framework.