A New Experimental Approach to Evaluate Coal Particles Floatability: Bubble–Particle Attachment and Detachment Kinetics

摘要

Coal floatability evaluation is of vital importance in the prediction of flotation results and the design of a flotation flowsheet. In this work, a new experimental approach based on bubble–particle attachment kinetics (BPAK) and bubble–particle detachment kinetics (BPDK) were proposed to evaluate the floatability of coal particles. During attachment and detachment processes, a variation of coating angles θ(t ) for different density coal particles were measured and fitted to a first-order model. Modified attachment rate constant k a) *) and modified detachment rate constant k d) *) were used as yardsticks of floatability. For comparison, flotation kinetics, induction time, and contact angle measurements were also conducted. A consistent sequence of floatability was obtained as: ?1.4 > 1.4–1.6 > +1.6 g/cm~(3). The modified flotation rate constant k * obtained in flotation kinetics was used as a yardstick to assess the accuracy of floatability evaluation methods. By individually fitting k * to parameters obtained in other tests, a simple and close linear relationship between k * and modified attachment rate constant k a) *) was established, rather than 1/k d) *) in BPDK tests, induction time t _(ind), or (1 – cosα) in contact angle measurements. Consequently, k a) *) is thought to be a better criterion as k * could be quantitatively predicted by BPAK tests. Throughout this work, BPAK is an effective method to evaluate coal floatability.