The estimation of the flotation rate constant is generally considered difficult because of the number of variables - not always measurable - determining its value. Among them, the particle size distribution and hydrodynamic characteristics are considered key elements. Part 1 of this paper introduced the interfacial area of bubbles (I-b) as a hydrodynamic variable providing more information about the size distribution than the bubble surface area flux (S-b). Fundamental expressions were proposed to characterize I-b using the population mean and standard deviation. Experimental results indicated that for lognormal bubble size distributions, I-b correlates very well with the gas hold-up and d(32). Part 2 investigates the correlation between the flotation rate constant and particle size as well as given hydrodynamic variables using a Projection to Latent Structures (PLS) analysis. The tests were conducted under 'ideal' conditions (i.e. shallow froth, low mineral concentration and pure mineral particles). Results suggest that for the fine particle sizes, the bubble surface area flux (S-b) should be considered for the kinetic constant modeling. For coarser particle, the gas hold-up (epsilon(g)) is the determining parameter. In practice though, the particle size distribution often lies between these two extreme cases, and can either span a very large range or contains intermediate size particles. In such cases, the interfacial area of bubbles (I-b) better correlates with the flotation kinetics. (C) 2014 Elsevier Ltd. All rights reserved.