The mass flowrate of particles (ton/h), entering the froth by true flotation, was evaluated from direct measurement of bubble load (ton/m(3)) and gas flowrate (m(3)/h). This information, together with the concentrate mass flowrate, allowed the estimation of the froth recovery of floatable mineral in a 130 m(3) rougher flotation cell. It was found that mineral transport along the froth was mainly non-selective, and also the contribution of valuable minerals recovered by entrainment was negligible, if compared with minerals recovered by true flotation. Thus, a direct estimation of the froth recovery was obtained, without arbitrary assumptions about the grade of mineral transport by entrainment and drainage. This simple procedure allows a non-biased and independent evaluation of the effect that design and operating variables have upon the collection and froth zones performance, in large flotation cells. The use of this approach for flotation cells diagnosis and development of new control strategies is considered. (C) 2008 Elsevier Ltd. All rights reserved.