Surface physicochemical properties and flotability modulation of smithsonite by regulating crystal morphology and cleavage process via grinding media

Smithsonite frequently undergoes surface cleavage along distinct crystallographic orientations during grinding. However, research addressing the anisotropy and surface wettability correlations of smithsonite remains unexplored. This study investigated the effects of different grinding media on smithsonite particle morphology and surface physicochemical properties. Laser particle size and SEM analyses revealed that the point loading generated by ball media induced uneven cleavage of smithsonite crystal. Conversely, the spalling forces of rod media promoted sharp edges and angular features, indicative of preferential natural cleavage. Enhanced elongation and flatness facilitated superior bubble adhesion for rod ground particles. XRD, flotation, and contact angle experiments demonstrated that ball ground particles exhibited significant cleavage anisotropy, preferentially exposing hydrophilic (0 1 2) cleavage surfaces. The (0 1 2) surface of smithsonite crystal exposed undercoordinated unsaturated Zn atoms with heightened reactivity. In solutions, preferentially formed hydroxyl compounds and hydration layers on (0 1 2) surfaces hindered oleate adsorption. These findings were corroborated by the molecular orbital matching theory and adsorption simulation. Comparatively, rod grinding effectively suppressed the expression of cleavage anisotropy of smithsonite. The predominant exposure of hydrophobic (1 0 4) surfaces enhanced collector adsorption and improved smithsonite flotability. This work is expected to guide the grinding and flotation from a new perspective of crystal surface properties.