Elucidating the Mechanism and Performance of Sodium Oleate Direct Flotation for Hemimorphite: A Novel Hallimond Tube Approach

To explore the differences and mechanisms of fatty acid collectors in the direct flotation of hemimorphite with varying particle size distributions, flotation experiments were performed using a home-developed Hallimond tube. With the rotational speed maintained at 200 revolutions/min, aeration rate set to 60 mL/min, pulp pH value of 10, the sodium oleate dosage of 70 mg/L, and the particle size range of -0.15 + 0.074 mm, the flotation recovery of hemimorphite could be boosted to over 99%. Ca²⁺ and Mg²⁺ ions were observed to exert a strong inhibitory effect on the flotation of hemimorphite particles in the +0.074 and -0.025 mm size fractions. The interaction mechanism was investigated via simultaneous thermogravimetry differential scanning calorimetry (TG-DSC), zeta potential measurement, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). These analytical results demonstrate that, under optimal conditions, adsorption involves chemical and hydrogen bonding interactions, with sodium oleate exhibiting strong collecting capacity for hemimorphite due to the synergistic effect of these two interactions. This research uncovers the flotation performance and adsorption mechanism in the direct flotation of hemimorphite with varying particle size distributions using sodium oleate. It also provides theoretical insights for the efficient flotation separation of hemimorphite.