• Sulfidation roasting with sulfur successfully converts stibiconite to stibnite (Sb2S3), achieving a flotation recovery of 90.3%.
• The adsorption capacity of sodium butyl xanthate on the roasted products increases with higher S/Sb mole ratio, directly enhancing floatability.
• XPS and EPMA analyses reveal that Sb2S3 forms predominantly on the particle surface while the interior remains antimony oxides, with sulfur inducing outward oxygen migration.
• These findings provide theoretical support for the sustainable recovery of antimony from antimony oxide ores using xanthate flotation.