Benzohydroxamic Acid as a Collector for Flotation of Chrysocolla: Mechanistic Insights and Bench-Scale Performance

Chrysocolla, a hydrated copper silicate mineral, is notoriously difficult to recover by conventional froth flotation due to its microporous structure, low hydrophobicity, impurity substitutions, and poor response to traditional collectors. This study evaluates the performance and adsorption mechanism of benzohydroxamic acid (BHA) as a collector for chrysocolla flotation under varying pH conditions and collector dosages. Microflotation results showed that chrysocolla recovery increased with BHA concentration, with enhanced flotation occurring at alkaline pH (8–10), consistent with BHA dissociation behavior. Zeta potential measurements indicated selective adsorption of BHA on the chrysocolla surface, while quartz showed minimal interaction, confirming collector selectivity. X-ray photoelectron spectroscopy (XPS) revealed that BHA was chemisorbed through Cu–hydroxamate complex formation. Bench-scale flotation tests on a chrysocolla ore containing 3.7% Cu produced a concentrate grading 26.7% Cu with 35.3% recovery after initial sulfide flotation. Kinetic tests indicated rapid recovery of more floatable copper phases, while scanning electron microscopy (SEM) showed preferential flotation of finer particles. Overall, the results demonstrate that BHA can effectively promote chrysocolla flotation through selective chemisorption, although high collector dosages are required due to the mineral’s high specific surface area and structural complexity.