An apparent detachment rate (ADR) of a species is defined as the difference between the bubble transport of the species directly below the pulp-froth interface and its corresponding final transfer into the concentrate. The ADR shows a definite relationship with the superficial velocity of water below the pulp-froth interface, the surface area/mass ratio of particles, as well as the floatability (hydrophobicity) of particles. An empirical relationship is proposed whereby the percentage apparent detachment (PAD) of a species can be predicted from these parameters. The PAD decreases with an increase in the upward superficial velocity of water, while a decrease in the floatability of particles (especially those with low area/mass ratios) results in an increase of the PAD. It is expected that the empirical model for the estimation of PAD could be useful to assist in the general assessment of flotation conditions in other applications. (C) 2003 Elsevier B.V. All rights reserved.