Determination of Optimum Parameters for Flotation of Galena: Effect of Chain Length and Chain Structure of Xanthates on Flotation Recovery

The structure of the xanthates’ hydrocarbon (C–H) chain is one of the major factors which affect flotation recovery. The effectiveness and the collecting power of xanthates increase with increasing chain length and vary depending on the chain structure: branched and straight chains. In this regard, the influences of length (2–5 carbon) and structure (straight: normal and branched: iso) of xanthate’s hydrocarbon chain on flotation recovery of galena were investigated under different experimental conditions: xanthate concentration, conditioning time, air flow rate (AFR), and air bubble size. Because of the steric effects of the chain structure, the branched chain xanthates gave lower flotation recoveries with shorter conditioning times compared to those with straight chain xanthates. Over-conditioning with straight chain xanthates resulted in hydrophobic aggregation of galena particles which resulted in the detachment of galena particles from air bubbles due to increasing weight, leading to lower flotation recoveries. In the case of flotation with different AFRs, the flotation recoveries increased with increasing AFR to 7 lph and further increase in AFR (10 lph) negatively affected the flotation recoveries when particles had insufficient hydrophobic surfaces. The maximum flotation recoveries were obtained with the addition of MIBC (methyl isobutyl carbinol) as a frother; the size of the air bubbles deceased with increasing MIBC concentration which increased higher encounter/collision probability of air bubbles with galena particles, resulting in higher flotation recoveries.