Control of rougher flotation circuits aided by industrial simulator

Today, large size mechanical flotation cells of 100–300 m3 are used in rougher operation in different flotation industrial plants, in Chile and worldwide. However, in spite of the advances in fundamental research and the notable growing in equipment size, with more complete instrumentation systems, there are still a lack of reliable data for industrial flotation modeling and simulation to advance in better control systems design. In this work, a procedure for modeling and simulation of rougher flotation banks, based on operating variables and parameters fitted from industrial data, is presented in condensed form. Recently, a new methodology for describing the industrial flotation, separating the collection and froth zones, has been developed. A non-linear distributed model to simulate rougher flotation circuits was developed, based on measurements of the main operating variables. The simulator was calibrated and tested using experimental data from the rougher operation at El Teniente Division, Codelco-Chile. The simulator was first used to sensitize the effect of changing the froth depth profile on target variables, and then to find out the best profile to reject common disturbances coming into the plant, considering some operating constraints. The flotation circuit simulator was then redesigned to incorporate an expert system following the proposed control algorithm. Several tests were performed by simulation to evaluate the control responses to different correlated series of input variables, such as feed grade, tonnage, particle size distribution, and solid percentage. Control alternatives based on the circuit simulator are discussed.

► We discuss the general problem of controlling a flotation plant and how a process model can be used to select the froth depth profile.
► We show how to build a model from industrial data: the design of experiments and a procedure for parameter estimation.
► We use the model to build a simulator to investigate how to improve the metallurgic of a rougher flotation circuit by setting the froth depth profile.
► We use an expert system included in the simulator to test by simulation the proposed control strategy under different disturbances.