Enhanced Recovery of an Arsenopyrite-Type Gold Ore: Flotation Surface Chemistry and Kinetics of Blended Collector W8 with ADD

This study investigated the flotation performance of W8, a blended xanthate collector containing ethyl, butyl, propyl, and amyl xanthates, combined with ammonium dibutyl dithiophosphate (ADD) for treating low-grade arsenopyrite-type gold ore from Golmud, Qinghai. Real ore flotation tests demonstrated the superior efficacy of the W8 + ADD system, achieving 84.06% gold recovery with 0.34 g/t tailings, outperforming conventional sodium amyl xanthate (SAX) + ADD and sodium propyl xanthate (SPX) + ADD systems. Systematic studies on pure arsenopyrite revealed a significant synergistic effect in the mixed SPX-SAX system (1:4 ratio), representative of W8 composition. At pH 9, the mixed collector achieved 73.5% recovery, substantially higher than individual SPX (37.5%) or SAX (45.8%). This enhanced performance was attributed to improved surface hydrophobicity (contact angle 47.68° vs. 36.92° for SAX), greater adsorption density (4.97 × 10−7 mol/g under depressant conditions), and extensive formation of molecular aggregates observed via AFM, which increased surface roughness to 28.95 nm. Flotation kinetics further confirmed the advantage of W8 + ADD, which reached 72.1% cumulative recovery in 420 s, exceeding both mixed SPX/SAX (69.5%) and single SAX (65.5%) systems. The synergistic interaction among different xanthate components in W8 enables efficient recovery of gold from this refractory ore.