The mechanism of selective separation of stibnite and arsenopyrite by Cu2+ coordination assembly KBX collector

The similar physicochemical properties of stibnite and arsenopyrite resulted in the difficult separation by traditional collectors in flotation. Hence, this study utilized Cu²⁺ and potassium butyl xanthate (KBX) coordinate assembly to form a novel Cu-KBX complex collector, investigating its properties, conformation, and its role in flotation separation of stibnite and arsenopyrite, as well as its diverse adsorption behavior on mineral surfaces. The stable Cu-KBX complex solution was formed when the molar ratio of Cu²⁺ to KBX was 1:2, exhibiting a network-like structure at that time. The micro-flotation results showed that at pH 5, the grade of Sb in the concentrate was as high as 61.08 %, with As content at only 4.65 %, enabling effective separation of stibnite and arsenopyrite. Furthermore, the Cu-KBX complex exhibited a reticulated structure at the stibnite surface, while it adhered in a granular fashion on the arsenopyrite surface. FTIR analysis confirmed stronger chemisorption of Cu-KBX onto stibnite compared to arsenopyrite. XPS results indicated that Cu-S was the main collecting component. However, a weak Fe(II)-S substance was found on the arsenopyrite interface, likely due to Fe³⁺ oxidizing in the slurry with the Cu-KBX complex. Therefore, this disruption of the Cu-KBX complex structure by Fe³⁺ in arsenopyrite sharply reduced its adsorption on arsenopyrite, enhancing the selective separation of stibnite and arsenopyrite.