This work tackles the problem of dynamically optimising the performance of a mineral concentration plant, taking into account economic profits and technical constraints. The paper proposes a two-level control strategy with regulatory control and the optimisation of an objective function. The regulatory control employs linear model based multivariable predictive controllers with constraints on controlled and manipulated variables, while the optimiser maximises the economic profits using non-linear dynamic models and linear constraints. The results, drawn from simulations, show the proposed strategy to lead to a significant improvement in economic profits when compared against an exclusively regulatory strategy.