Kinetic Studies on Petrographic Components of Coal in Batch Flotation Operation

ABSTRACT

In the present paper, an attempt was made to study the kinetic behavior of different types of maceral during flotation of a washery grade-IV type of coking coal. Three important operational variables, viz. collector dose (kg/ton), frother dose (kg/ton), and feed solid concentrations (%), were varied, and their effects on the response parameters like recoveries of ash and petrographic components, viz. vitrinite (V), liptinite (L), and inertinite (I), were evaluated. A first-order flotation kinetic equation $R=R\mathrm{\infty }\left(1-e^{-kt}\right)$was fitted for the batch test data for evaluating the rate of flotation (k) of coal components. Use of a three-level Box-Behnken factorial design was adopted to minimize the number of experiments and modeling of response parameters in batch coal flotation. The obtained results were evaluated with quadratic programming to develop second-order regression equations. For understanding of the influence of interactional effects, response surface methodology (RSM) approach was adopted. Taking advantages of the quadratic programming, it was observed that recovery of 100% vitrinite was obtained without collector, however, with frother dosage and feed solid concentration of 0.75kg/ton and 5%, respectively. Similarly, minimum ultimate recovery of ash and inertinite component was achieved at intermediate range of reagent dosages and pulp density (collector ≡ 0.40–0.45kg/ton, frother ≡ 0.40–0.45kg/ton, and feed solid concentration of 9–10%). The influence of these process variables of the batch coal flotation on ultimate recovery (R_∞) and rate constant (k) values of maceral components are discussed critically in this paper.

KEYWORDS:

• Batch coal flotation
• flotation kinetics
• macerals
• modeling
• optimization
• reagent dosages