First-order flotation kinetics models and methods for estimation of the true distribution of notation rate constants

To improve their versatility, many first-order flotation kinetics models wi th distributions of flotation rate constants were redefined so that they co uld all be represented by the same set of three model parameters. As a resu lt, the width of the distribution become independent of its mean, and param eters of the model and the curve fitting errors, became virtually the same, independent of the chosen distribution function. For the modified three-pa rameter models, the curve fitting errors were much smaller and their robust ness. measured by PRESS residuals, was much better when compared to the cor responding two-parameter models. Three different methods were compared to p erform flotation kinetics analysis and estimate model parameters. In Method I, recovery vs. time data were used to obtain model parameters. No signifi cant insight into the distribution of rate constants could be obtained beca use the distributions were presupposed. In Method II, the froth products we re fractionated into several size fractions and the data for each fraction were fitted to a model. This task was easy to perform and the method could describe the flotation kinetics reasonably well. In method III, flotation p roducts were fractionated into many size-specific gravity fractions. The pr ocedure involved a large amount of time and effort and it generated relativ ely large errors. Based on the analysis presented in this article, it was c oncluded the smallest errors were obtained with Method II. The overall dist ribution of flotation rate constants could be obtained from a weighted aver age of the distributions of individual size fractions. The distributions so obtained were demonstrated to be less sensitive to the choice of the model used to represent the kinetics of individual size fractions, and therefore can be assumed to be "true" representation of the flotation rate distribut ion. (C) 2000 Elsevier Science B.V. All rights reserved.