Operational and metallurgical assessment of column flotation for Pb tailings processing

Column flotation offers improved selectivity and fine-bubble generation for recovering residual metals from flotation tailings. This study investigates Pb recovery from the scavenger tailings of the Angouran Pb–Zn concentrator using a 90 mm × 1500 mm laboratory column and applies a Central Composite Design (CCD) with Response Surface Methodology (RSM) to assess the effects of froth height, feed flow rate, wash water flow rate, and air flow rate. Metallurgical and hydrodynamic responses, including Pb grade, Pb recovery, gas holdup, and residence time, were evaluated. Under optimized conditions (feed = 0.5 L/min, wash water = 100 mL/min, froth height = 28 cm, air = 2.9 L/min), a Pb grade of 7.49 wt.% and recovery of 34.1% were achieved. Froth height and wash water were the main determinants of concentrate grade, while air flow rate and froth height governed recovery and gas holdup. A key innovation of this research is the introduction of the Gas-Solid Interaction Factor (GSIF), a novel linear index derived from the normalized product of grade and recovery, which successfully correlates process efficiency with the gas-to-density ratio (R2 = 0.96). The findings highlight the strong hydrodynamic–metallurgical coupling and demonstrate that column optimization or cleaner-column integration can enhance Pb recovery from tailings.