The stator is a standard component in mechanical flotation cells, designed to promote key hydrodynamic processes. It has a baffling effect that suppresses swirling, improving both mixing and gas dispersion. The stator also promotes bubble break-up and intensifies turbulence, thereby increasing bubble–particle interactions (Fallenius, 1987; Ralston & Dukhin, 1999; Gorain et al., 2000). However, flotation research suggests that the rotor-stator combination may be sub-optimal for solids suspension. According to Fallenius (1987), the stator converts a substantial portion of impeller energy into turbulence, at the expense of mean flow energy. Particle suspension is more effective when mean flow dominates (Nagata, 1975; Nguyen & Schulze, 2003; Paul et al., 2004). This issue becomes more critical for coarse particles. Van der Westhuizen & Deglon (2008) reported that particle size has a greater influence on the critical impeller speed in flotation cells than in stirred tanks. The authors attributed this effect to the stator. In mixing tanks, baffles are commonly used to suppress swirling and enhance solids suspension (Walas, 1988; Paul et al., 2004). Compared with baffles, the stator 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).
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