Selective passivation of arsenopyrite surface using a novel eco-friendly oxidant, sodium percarbonate, for Cu–As flotation separation

This study investigates the effect of sodium percarbonate (SPC) as an eco-friendly oxidant on the flotation separation of bornite and arsenopyrite. Micro-flotation tests demonstrated that SPC significantly suppressed arsenopyrite floatability while maintaining bornite floatability. In artificial mixed-ore tests conducted at pH 10 with 500 mg/L SPC and 5 × 10 −5 mol/L sodium butyl xanthate (NaBX), bornite recovery reached 87.93 %, whereas arsenopyrite recovery was only 14.51 %, which resulted in a substantial recovery difference of 73.42 %. Surface analysis via contact angle measurements, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), atomic force microscopy (AFM), localized electrochemical impedance spectroscopy (LEIS), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed that SPC treatment enhanced the hydrophilicity of arsenopyrite compared with that of bornite. LEIS, XPS, and ToF-SIMS confirmed the formation of hydrophilic oxides such as FeAsO 4 , H 3 AsO 3 , Fe(OH) 3 , and Fe 2 (SO 4 ) 3 on arsenopyrite surfaces, which ultimately reduced floatability. In contrast, bornite surfaces exhibited only slight oxidation, with minimal increases in Cu(OH) 2 , Fe(OH) 3 , and Fe 2 (SO 4 ) 3 which only resulted in a modest decrease in floatability. SEM–EDS and AFM analyses revealed significant changes in the surface morphology of arsenopyrite after SPC treatment, with increased oxygen content and surface roughness, which indicated the formation of an oxide layer. In contrast, bornite surfaces remained relatively smooth, with only a slight increase in oxygen content. This study provides valuable theoretical reference into the use of eco-friendly depressants for copper–arsenic mineral separation.