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Description
Froth flotation is an essential separation technique in the mining industry, primarily used to extract valuable minerals from ores. Traditionally, this process targeted particles measuring tens or hundreds of micrometers. However, the recent depletion of high-grade ore deposits has prompted a shift towards exploiting lower-grade mineral deposits. This transition necessitates the fine grinding of ores to effectively
liberate the embedded valuable minerals, introducing new challenges associated with managing fine and ultrafine particles.
A notable complication arising from the presence of ultrafine particles is their propensity to excessively stabilize the froth. This excessive stabilization can hinder the flotation process, as overly stable froth impedes the drainage of gangue particles back into the pulp, thus diminishing the grade and selectivity of the concentrate. The stability of the froth is influenced by factors such as the size, hydrophobicity, and shape of the particles. In this study, we investigate the effect of ultrafine particles on the stability of thin liquid films. Through interferometric experiments, we have analyzed how variations in particle concentration and hydrophobicity impact thin film stability. Our findings highlight the significant role of adsorption time on film stability. We categorized the behavior of liquid films with adsorbed ultrafine particles into three distinct types: freshly formed films that ruptured within seconds, films aged for 15 minutes which displayed an extended lifespan with notable thickness variations (Fig. 1 a,b), and films aged for 30 minutes which maintained stability for significantly extended periods 1.
Furthermore, we investigated the attachment dynamics of coarse particle in the presence of ultrafine particles using a model stirred cell that enables precise control over hydrodynamic conditions 2. Our experiments showed that ultrafine particles not only enhance the attachment rate and probability of coarser particles but also significantly influence the distribution of coarse particles on a bubble surface (Fig. 2 c,d). Additionally, the mobility of coarse particles at the interface changes markedly when ultrafine particles are adsorbed on the bubble surface, which is anticipated to alter the flow structure and flowdriven processes near the bubble, such as the detachment of attached particles.
