Abstract

LIAO, Y. et al. Comparison of the effect of particle size on the flotation kinetics of a low-rank coal using air bubbles and oily bubbles. J. S. Afr. Inst. Min. Metall. [online]. 2017, vol.117, n.6, pp.561-566. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2017/v117n6a6.

The effect of particle size on the flotation kinetics of a low-rank coal was compared using air bubbles and oily bubbles. Five kinetic models were applied to the data from the tests to derive the relationships between the flotation rate constant, the ultimate recovery, and the particle size fraction. The results show that oily bubble flotation (OBF) resulted in a lower ash content and higher combustible recovery than air bubble flotation (ABF), especially for the -125 μm size fraction. It was found that the flotation of a low-rank coal in individual size fractions using air bubbles and oily bubbles can be best described by a first-order model with rectangular distribution of tendency to float and the classical first-order model respectively. OBF yielded higher ultimate combustible and ultimate ash recoveries. The flotation rate constants for OBF were higher in all the models except for the fully mixed reactor model. The ultimate recovery values and modified rate constants first increased and then decreased as the size fraction decreased. The trend of the flotation rate constants as a function of the size fraction was similar in all the models except for the fully mixed reactor model.

Keywords : particle size; flotation kinetics; low-rank coal; oily bubble; air bubble.

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