650 promotes turbulence and influences fluid velocities more significantly (Mesa, 2020). This can be detrimental for particle suspension and may therefore increase the impeller speed required for just suspension (Njs). Operating a flotation cell at the Njs ensures that all particles are lifted from the cell bottom with minimal turbulence. This condition is considered optimal for coarse particle flotation, as it maximizes particle-bubble contact while minimizing detachment forces (Newcombe et al., 2012; Awatey, 2015). A cell configuration that requires a higher impeller speed to achieve the just suspension condition (Njs)— potentially the rotor-stator system—likely leads to reduced coarse particle recovery. Higher impeller speed typically increases turbulence and power consumption, promoting bubble– particle detachment. Coarse particles are particularly prone to detachment due to their physical properties (Rodrigues et al., 2001; Nguyen & Schulze, 2003; Tabosa, 2012; Fosu et al., 2015). It may also intensify oscillations at the pulp-froth interface, which can increase coarse particle drop-back to the pulp (Falutsu & Dobby, 1989; Seaman et al., 2006). Despite these implications, the potential of baffles as an alternative to the stator in mechanical flotation cells has not been thoroughly investigated. This study investigates the effect of replacing the stator with baffles in a 1 m³ mechanical flotation cell. The objective is to evaluate how these two configurations influence coarse particle suspension, power draw, and interface oscillations under varying air rates. 2. EXPERIMENTAL Experiments were performed in a 1 m³ mechanical flotation rig with a transparent cylindrical tank of 1.15 m diameter (Figure 1). Figure 1 – Pilot flotation rig The cell was operated in batch mode (i.e. with no feed or tailing discharge). Water and silica were added directly to the tank prior to testing. The static pulp height was 0.57 m. Agitation was provided by a 6blade Tailing Technology rotor (0.205 m diameter) driven by an 11-kW motor through a V-belt assembly, with a variable-speed drive to control the impeller speed. Impeller speed was measured with a digital tachometer. The rotor was positioned 0.10 m above the tank bottom. Air was supplied by a blower, controlled using a manual valve, and flowrate measured by a digital mass-flow sensor. Frother (Methyl isobutyl carbinol - MIBC) was added to the pulp at 100 ppm to stabilize bubble size.
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