The impact of milling media and chemical conditions in the milling process for the flotation of a mixed-sulfide ore

• Gn and Py galvanic contact significantly affected Pb dissolution across all studied conditions. • Iron (Fe) from FS milling media is more susceptible to oxidative dissolution than pyritic Fe. • Milling media and water composition did not markedly affect Pb grades and recoveries at pH 10. • FS milling at all examined water compositions proved more effective in controlling Fe recovery. • High ionic strength water, mimicking water recycling, showed little effect on recoveries. Chemical reactions during milling and flotation are mostly driven by interactions between minerals, reagents, milling media, and water chemistry. Furthermore, due to these interactions, the valuable minerals may become more difficult to float, especially in the case of polymetallic ore processing in closed-water circuits. This study uses a mixed mineral − galena (Gn) and pyrite (Py) − synthetic ore sample to investigate how metallurgical performance is affected using different milling media, pHs in the mill, and process water ionic strengths. Mixed potential, DO, and pH were closely monitored in situ during milling. Using Gn and Py as the minerals of interest allows the effect of iron (Fe) in the mineral to be decoupled from that arising from the mill shell and Fe-bearing milling media.