The effect of particle size distribution on froth stability in flotation

Abstract

Separation of particles of different surface properties using froth flotation is a widely-used industrial process, particularly in the minerals industry where it is used to concentrate minerals from ore. One of the key challenges in developing models to predict flotation performance is the interdependent nature of the process variables and operating parameters, which limits the application of optimising process control strategies at industrial scale. Froth stability, which can be quantified using air recovery (the fraction of air entering a flotation cell that overflows in the concentrate as unburst bubbles), has been shown to be linked to flotation separation performance, with stable froths yielding improved mineral recoveries. While it is widely acknowledged that there is an optimum particle size range for collection of particles in the pulp phase, the role of particle size on the measured air recovery and the resulting link to changes in flotation performance is less well understood. This is related to the difficulty in separating particle size and liberation effects.In this work, the effects of particle size distribution on air recovery are studied in a single species (silica) system using a continuous steady-state laboratory flotation cell. This allows an investigation into the effects of particle size distribution only on froth stability, using solids content and solids recovery as indicators of flotation performance. It is shown that, as the cell air rate is increased, the air recovery of the silica system passes through a peak, exhibiting the same froth behaviour as measured industrially. The air recovery profiles of systems with three different particle size distributions (d80 of 89.6, 103.5 and 157.1 m) are compared. The results show that, at lower air rates, the intermediate particle size distribution (103.5 m) yields the most stable froth, while at higher air rates, the finest particles (89.6 m) result in higher air recoveries. This is subsequently linked to changes in flotation performance. The results presented here highlight, for the first time, the link between particle size distribution in flotation feeds, air recovery and flotation performance. The results demonstrate that there is an optimal air rate for each particle size distribution, therefore changes in particle size distribution in the feed to flotation cells require a change in air rate in order to maximise mineral recovery.

Froth Production in Potable Water without Chemicals

“…These small bubbles have two main positive effects, first, in supporting the original big bubbles to form the desired froth, while the second is attaching and lifting micro-particles effectively, as the best bubble size for such techniques is close to separated particles size (Hanotu et al, 2012;Norori-McCormac et al, 2017). The increase in Kla along the range of (30-110 l/min) is not exactly proportional.…”

Desulfurization of Iron Ores: Processes and Challenges

“…Particle size distribution is one of the key parameters in the separation of minerals using flotation process . The flotation processes of iron ore, either in mechanical cells or in columns, are fed with particles with sizes between 10 and 150 μm, while froth flotation is generally limited to size fractions between 65 and 100 mesh, particles larger than 65 mesh Tyler (210 μ) are difficult for the air bubble to lift and particles smaller than 400 mesh (37 μ) are often not attached to the air bubble .…”

High-energy ultrasound to improve the quality of purifying the particles of iron ore in the process of its enrichment

“…In the process of enrichment, as shown by studies [31,32], it is necessary to take into account the distribution of physical and mineralogical characteristics of ore in terms of grain size classes. These characteristics of ore raw materials become particularly important in the process of flotation [33,34]. The justification for the need to select the technological parameters of the flotation process in accordance with the distribution of the size of the ore particles is proposed in [33].…”

“…These characteristics of ore raw materials become particularly important in the process of flotation [33,34]. The justification for the need to select the technological parameters of the flotation process in accordance with the distribution of the size of the ore particles is proposed in [33]. In work [34], the influence of chemical characteristics of ore particles on the efficiency of the flotation process is investigated.…”