Assessment of the partitioning of coarse hydrophobic particles in the product concentrate of the CoarseAIR™ flotation system using a novel mechanical cell reference method

Abstract

A new algorithm was developed to assess the coarse particle flotation performance of the CoarseAIR™ system. The objective was to quantify the partitioning of the hydrophobic particles of the feed to the overflow product concentrate stream and to the underflow reject stream, recognising the broad extent of the particle surface liberation. To assess the coarse particle flotation performance, steady state samples of the feed, overflow product concentrate, and underflow reject streams of the CoarseAIR™ were taken and the +90 μm portions used to perform batch mechanical cell flotation kinetic tests. Measurement of the flotation kinetics of all three streams was undertaken, including the ultimate recoveries of the hydrophobic particles. The algorithm was constrained by the need to describe the flotation kinetics of all three streams while also adhering to full material balance requirements within each stream and between the hydrophobic components of the three streams. The algorithm produced an overall partition curve for the CoarseAIR™ separator covering the size range from 90 to 600 µm, describing the probability of a particle having a given rate constant, k, reporting to the overflow product concentrate. At a partition number of 0.50, the value of k is referred to as k50. Hydrophobic particles having this rate constant have an equal probability of reporting to the product and the reject. The partition curve was then determined as a function of the normalised rate constant, k/kmax. Here, the value of k50/kmax was ∼0.06. Based on a previous study, this value can be used to infer a surface liberation of ∼22%. The same approach was also applied to specific narrow size fractions, resulting in similar partition curves, with the value of k50/kmax increasing with the particle size.