Investigating hydrodynamics of a laboratory-scale ImhoflotTM V-cell in recovering ultrafine magnesite from a dolomite-rich tailing

Abstract

Abstract

Recovering ultrafine magnesite from dolomite-rich desliming tailings faces significant challenges due to the fine and ultrafine particle sizes, the similar physicochemical surface properties of magnesite and dolomite, and a lack of advanced technological solutions in froth flotation. This study introduces a novel approach by investigating the hydrodynamic properties of a laboratory-scale pneumatic ImhoflotTM V-018 (Vertical V-cell type, 180 mm diameter) flotation cell as a potential solution to enhance the recoverability of ultrafine magnesite particles. The research comprises three key components: bubble size distribution analysis, hydrodynamic performance testing for the aeration system and feed flowrate measurements, and flotation experiments. Bubble size measurements conducted in two-phase (air–water) by investigating the effects of MIBC frother dosage and air flowrate. Results showed that increasing the MIBC frother dosage reduced bubble size and enhanced stability, while air flow had a dual effect on bubble size, depending on the range. Hydrodynamic performance tests resulted in smaller nozzle venturis producing higher pressures with Aerator B (venturi cascade). Flotation experiments studied two aerators (i.e., flotation reactors) with varying aerator diameters, pulp densities, air flowrates, and feeding positions. The highest recovery for magnesite (86.4 %- Rmax, experimental and 87.1 %- R∞ modelled) with a kinetic rate constant (k) of 0.09 min−1 was achieved at 4 L/min air flowrate, whereas the maximum grade 78.8 % was obtained with Aerator B (venturi cascade) and a nozzle diameter of 4.8 mm. Moreover, Aerator B demonstrated better selectivity across all mineral pairs compared to Aerator A (standard venturi aerator), achieving a maximum selectivity index of selectivity index of 5.2 for magnesite/quartz. These findings underscore the ImhoflotTM V-018 cell’s potential, especially with the integration of the novel Venturi cascade reactor, whose unique hydrodynamic environment improves gas–liquid interaction and particle collision efficiency over traditional methods and setting a new standard for ultrafine magnesite recovery.