599 of conventional flotation technologies (i.e. agitated mechanical cells) to recover composite particles greater than 150 µm. The agitation caused by the impeller in a mechanically agitated flotation cell is detrimental to the flotation of coarse particles, which requires very low turbulence to minimize detachment (Kohmuench et al., 2013). The introduction of coarse particle flotation (CPF) devices, like the HydrofloatTM, aimed to solve this challenge. These devices included a low turbulence fluidized bed, targeting improved recovery of valuable minerals in the coarse size fractions (+150 µm). Despite the clear benefits, the industrial devices implemented have highlighted some challenges as well. Concha et al. (2023) explained that due to the negative bias caused by the fluidization water, it is best when the fine fraction of the feed is removed or reduced prior to treatment in the HydroFloatTM. Currently installed CPF devices operate “as air-assisted elutriators”, where bubbles attach to the hydrophobic sites of particles, increasing their buoyancy and drag. An upward stream of fresh water used to fluidize the teeter bed then carries these particles to the top of the vessel where the water and particles are collected as a concentrate. There is no froth layer in these “elutriation-type” CPF devices and therefore any fine particles present will be entrained into concentrate with the teeter water (Jaques et al., 2021). To reduce the water consumption of elutriation-type CPF devices, a cyclone cluster is installed on the product stream to recover some of this water. Figure 37 presents the typical flowsheet of current CPF circuits. As a result, current CPF industrial circuits are installed with up-front deslime circuits, most recently, these include multiple stages of cyclones to remove the finer size particles. However, the deslime circuit does not provide a perfect separation; and some fine material still enters the CPF devices, increasing gangue entrainment and diluting concentrates. Depending on the ore type and CPF application, the finer size fraction removed can be -106 µm, -75 µm or -53 µm. If the removed size fraction contains recoverable valuable minerals, then it is treated separately in a fines flotation circuit. Thus, in most cases a hybrid circuit is required to treat the full particle size range. Figure 37 – Typical flowsheet of current CPF circuits The NovaCell™ addresses the challenges of current CPF circuits and treats the full process stream. Since the NovaCell™ is a true froth-flotation machine with a froth layer that selectively recovers hydrophobic particles while allowing the drainage of water containing gangue particles, there is no requirement for a deslime circuit or an additional ‘fines’ flotation circuit. The NovaCell™ features a novel configuration that provides optimal hydrodynamic conditions for both fine and coarse particle recovery (Jameson, 2010). Particles and microbubbles first collide in high-shear downcomers, enhancing fine and ultrafine recovery, before the stream enters a fluidized bed where partially loaded bubbles capture coarse particles under low-shear conditions.
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