Modelamento de flotação por classes de tamanho e liberação

Abstract

Particle size and liberation are the ore characteristics that have the largest impact on flotation performance. The effects of these two factors have been extensively discussed and studied since the early years of flotation. However, it is still necessary to consolidate how liberation and size, in conjunction, affect flotation performance, using a real ore in a continuous circuit, under regular conditions and after correction of liberation data. In this work, the behaviour of size liberation classes was evaluated using a chalcopyrite ore floated in a continuous mini pilot plant circuit, with conditions equivalent to the industrial flotation in terms of particle size, solids percentage and feed mineralogy. To minimize error propagation in the liberation results, Savassi reconciliation method was used and optimized. This approach performs mineralogical correction while generates a hierarchical mass balance. Resulting liberation data became consistent with process data, providing a representative mass balance.The behaviour of size liberation classes according to the froth height was evaluated for the first rougher cell. The higher the froth, the higher the concentrate grade and the lower the recovery. This higher selectivity happened due to a progressive rejection of free gangue and low grade composite particles. Froth recovery was dependent on liberation and particle size. Two models were developed to describe the flotation of liberation classes: The first was an empirical mathematical model that represents flotation recovery of liberation classes in each particle size fraction. The second details and models the effect of liberation on flotation considering the mineral surface area. These models can be the basis for evaluating the effectiveness of grinding and flotation, and can also be included in mine-to-mill strategies