Theoretical and Experimental Aspects of Influence of Temperature on Kinetics of Carbonaceous Materials Froth Flotation

Abstract

ABSTRACT The relation between rate constant k 1 and absolute temperature T for graphite, anthracite, and coal floated with only frother was investigated using combined theoretical and empirical approaches. It was determined that the relation between lnk 1 and 1/T is curvilinear and requires a polynomial of a second degree for a sufficient approximation of the experimental data points. Therefore, the well-known Arrhenius empirical formula for chemical reactions, predicting a linear relation, cannot be used for relating lnk 1 and 1/T. Available in literature thermodynamic and kinetic considerations show that for chemical reactions and equilibrium processes the relation between the first order rate constant k 1 and absolute temperature T is lnk 1 = lnk −1-ΔHo /RT +ΔSo/R, where ΔHo is standard enthalpy change, ΔSo standard entropy change, R gas constant and k −1 is the rate constant of the reverse reaction, in our case the disintegration of the bubble-particle aggregate. Assuming that the performed batch flotation tests for a long time of flotation provide an equilibrium quantity called ultimate or maximum recovery, the values of enthalpy and entropy as well as reverse process rate constant k −1 were determined. It was found that k 1 depended on two constants (ΔHo and ΔSo) and two variables (1/T and k −1 = f(1/T)).