Optimization of Operating Parameters for Flotation of Fine Coal Using a Box-Behnken Design

Abstract

In this study, experiments were carried out to examine flotation characteristics of fine coal and to determine the effect of various reagents on the coal flotation and the most optimum flotation conditions. The aim of the study was to obtain low-ash content of froth products from a high-ash-containing feed. The flotation experiments were carried out in two steps. First the optimum flotation condition parameters, such as optimal particle size, frother type, conditioning time, solid-liquid ratio, depressant type, and effect of flocculants, were determined. In the second step, keeping the optimum conditions obtained from the first step constant, a Box- Behnken design was applied for modeling and optimization of some operating variables. Three independent variables are categorized as follows: collector dosage (0–2 kg/t), frother dosage (0.1–0.3 kg/t), froth collecting time (120–180 sec). The results obtained from the experiments were subjected to multiple regression analysis by using SPSSP19. A LOQO/AMPL optimization algorithm was used for the solution of the quadratic regression models. The R2 values of the second-order regression equation for ash content of clean coal and yield were calculated as 0.905 and 0.959, respectively. This showed a good relationship between observed and calculated values. Three-dimensional graphics were created to demonstrate the dependent and independent variables behaviors.