Predicting the chromite mineral upgradation in floatex density separator using hindered settling models

Abstract

Floatex density separator is a commercial hindered (teetered) bed separator and works on the principle of hindered settling. In hindered settling, prediction of the separation behaviour of mineral particles is complex and challenging, since the settling velocities of the particles are influenced by the nearby particles. In the present work, empirical hindered settling models available in literature have been successfully used for predicting the separation of chromite mineral in liquid fluidized bed created in Floatex Density separator (FDS) unit for the first time. Two hindered settling models have been used for predicting the performance of the FDS unit in terms of the weight recoveries and the mineral composition of the FDS underflow product. This predicted data is validated using the experimental data generated from three different random plant scale trials with FDS unit. The agreement between the results predicted from the model are found to be match with the experimental results with less than 5% error at low suspension densities and low teeter water velocities upto 25 mm/s. Therefore, the models have been further explored to study the effect of teeter water velocity on the chromite grade and overall chromite mineral recoveries within the model applicable range of teeter-water velocities. This has resulted in a fair amount of understanding of the separation behaviour of the chromite mineral in FDS and helped in choosing the operating parameters for production of desired grades of chrome concentrate as FDS underflow. Hence, the value of this paper is in its validation of simple hindered settling models and their application to predict recoveries and upgradation of chromite ore at industrial scale. © 2006 ISIJ.