Comparative Evaluation of Pine Oil and Vernonia amygdalina Extract as Frothers in the Froth Flotation of Duguri Galena for Lead Oxide Production

Abstract

The demand for eco-friendly reagents in minerals flotation is rising. Conventional frothers, while effective for flotation processes, are synthetic, raising environmental and sustainability concerns. Green frothers act as eco-friendly substitutes, reducing ecological impacts and improving biodegradability without compromising flotation performance. This study investigated the froth flotation of Duguri lead ore (Bauchi State, Nigeria) using conventional (pine oil) and non-conventional (Vernonia amygdalina extract) frothers to produce lead oxide concentrate suitable for pyrometallurgical extraction of lead metal. The sample underwent comminution and homogenization, followed by random sampling and particle size analysis. A grindability test was performed, and subsequent froth flotation experiments were conducted to concentrate the valuable lead mineral. The elemental composition of the ore sample was analyzed using Energy Dispersive X-ray fluorescence (ED-XRF), the morphological structure using Scanning Electron Microscope - equipped with Energy Dispersive Spectroscopy (SEM-EDS), and the mineral composition identified using X-ray Diffraction (XRD). The liberation size of the ore was determined to be within the range of -180+125 µm, with a work index of 22.20 kWh/t and a comminution energy of 3.76 kWh. The froth flotation method significantly increased the PbO grade. Pine oil achieved optimal results in the -125+90 µm size range, while Vernonia amygdalina extract performed better in the -63 µm fraction, yielding higher PbO grade, recovery, concentration ratio, enrichment ratio, and separation efficiency. Consequently, both frothers produced 60-65% PbO concentrates, suitable for pyrometallurgical extraction of lead metal. Therefore, Vernonia amygdalina extract emerges as a more efficient alternative frother to pine oil in the froth flotation of Duguri lead ore, offering an eco-friendly option, that reduces reliance on synthetic reagents while maintaining or improving metallurgical performance.