DYNAMIC SIMULATION OF OPERATING VARIABLES IN FLOTATION COLUMNS

Contributions to better control of flotation columns may come from imp rovements in different areas: measurements, dynamic and functional mod els, control strategies and control algorithms. Lack of process knowle dge, specifically on transient behaviour and interaction among variabl es, generally leads to low quality conventional distributed control an d partially inhibits further improvements. In this work, discrete mult ivariate dynamic models of operating variables were experimentally obt ained in a pilot column and then arranged to build a dynamic simulator prototype, for the air-water system. The main strategy was to use low order dynamic models between every independent and dependent variable , and to combine them linearly to predict the evolution of each variab le of interest, by solving a set of difference equations. Given an ini tial steady state (i.e. feed flowrate, wash water flowrate, openings o f tailing and air valves, froth depth, gas holdup and bias), the progr am running in a PC computer predicts the transient behaviour of the fr oth depth, the gas holdup and the bias, under any disturbance introduc ed in the independent variables over time. The program provides a frie ndly user interface to follow on-line the trends on screen and to recr eate the whole experience later on from data previously stored in hard disk during the experiment Comparison of predicted and experimental r esponses under different disturbances showed the effectiveness of the simulator following the general trends, and where further work to incl ude extreme nonlinear effects has to be done. The integration of dynam ic process models and control algorithms in a computer program has pro ved to be very useful in evaluating control strategies. `