Effects and Mechanisms of Grinding Media on the Flotation Behavior of Scheelite

Grinding, an essential procedure for size reduction and fresh surface exposure of mineral particles, plays an important role in mineral flotation. The grinding media are the key factors for effective grinding and thus for successful flotation. In this study, ceramic ball (CB) and cast iron ball (CIB), two representative grinding media, were chosen to investigate the effects and mechanisms of grinding media on the flotation behavior of scheelite. The results of pure scheelite flotation show that scheelite ground by CB has a better floatability than that ground by CIB. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analyses indicate that there are Fe species, namely, elemental iron (Fe), ferrous oxide (FeO), and iron oxyhydroxide (FeOOH), coated on the surfaces of scheelite ground by CIB but not in the case of scheelite ground by CB. The dissolved oxygen (DO) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) tests show that Fe ions exist in the CIB grinding slurry but not in the case of CB grinding slurry. Compared with the CB grinding slurry, the CIB grinding slurry has a lower DO content and higher Ca ion concentration. Zeta potential results reveal that the Fe species in the CIB grinding reduce the NaOl adsorption on the scheelite surfaces. Finally, the deleterious effect of CIB grinding on the flotation behavior of scheelite is verified by the actual scheelite ore flotation experiments.