Abstract

In this work, a new methodology to evaluate solids transport in the froth was tested and validated. The methodology was based on using solid radioactive tracers, which was implemented in a two-dimensional flotation cell. The prototype cell represented a radial section of an industrial flotation cell (130 m(3)) and was operated at steady state using a two-phase (air-water) system. The experimental tests consisted of adding a small amount of radioactive solid tracer (0.3 g) near the top of the froth (TOF) or near the bottom of the froth (close to the interface). A non-floatable mineral was selected as the solid to evaluate both the solids entrainment into the concentrate and the solids settling into the collection zone. The solid tracer consisted of fine and coarse gangue particles with Pep values of 35 and 120 mu m, respectively. Twelve collimated sensors located along the froth and collection zones allowed the evaluation of solids transport in the froth and solids settling from the froth to the collection zone after tracer addition at different distances from the discharge lip. The results obtained using the new methodology were in good agreement with the expected tendencies: a longer distance to the froth discharge lip as well as a coarser particle size promotes higher solids settling from the froth to the pulp zone while decreasing the solids entrainment into the concentrate. In addition, froth surface velocity measurements were performed using the Visiofroth system, and good agreement was observed between the froth bubble velocity and the solids transport velocity measured near the discharge lip. These results provide experimental evidence that solids radioactive tracers are a powerful tool to study and quantify particle motion in the froth, solids entrainment and solids settling into the collection zone.