The Distributed Rate Constant Model

About 10 years after Morris (T.M. Morris, Measurement and Evaluation of the Rate of Flotation as a Function of Particle Size, Trans AIME 193, 794-798, 1952) showed that the observed flotation kinetics could be explained by the presence of a non-floatable component, Imaizumi and Inoue (T. Imaizumi and T. Inoue, Kinetic Considerations of Froth Flotation, Proc. 6th Intl Mineral Processing Congress, 581-593, 1965) proposed that the kinetic rate constant should be regarded as a random constant with values spread over a wide range reflecting the inherent variability of the behavior of mineral particles. This idea was given practical application by Zaidenberg, Lisovskii and Burovoi (I. Sh. Zaidenberg, D.I. Lisowskii and I.A. Burovoi, One Approach to the Construction of a Mathematical Model for Flotation Processes, Soviet Journal of Non-Ferous Metals, English translation Vol 5, 26-32, 1964) who proposed that the mineral particle population should be divided into size classes, each size class should be divided into groups according to composition and each class of given size and composition into separate classes of floatability. This interesting and useful idea formed the basis of the first successful flotation plant simulator which was developed at MINTEK's Chemical Engineering research Group in the late 1960s and which was the precursor of MODSIM. This 3-way classification of the particles allows the simulator to keep track of each type of particle throughout the plant no matter how complex the flowsheet. For example, particles that belong to the non-floatable class remain non floatable in every flotation cell that they visit and particles that are associated with a high specific flotation rate constant retain that character throughout the plant.

MODSIM is built around the 3-way classification of particles and the third classification dimension uses the S-classes. MODSIM offers two flotation models based on the distributed rate constant model. Exercise 5-3 will use the simpler of these models and will introduce you to the use of S-classes in MODSIM.

Assignment 4 uses the full distributed rate constant model and introduces you to optimization of the layout of a flotation plant.