Kinetics of Dry-Batch Grinding in a Laboratory-Scale Ball Mill of Sn-Ta-Nb Minerals from the Penouta Mine (Spain)

The optimization of processing plants is one of the main concerns in the mining industry, since the comminution stage, a fundamental operation, accounts for up to 70% of total energy consumption. The aim of this study was to determine the effects that ball size and mill speed exert on the milling kinetics over a wide range of particle sizes. This was done through dry milling and batch grinding tests performed on two samples from the Penouta Sn-Ta-Nb mine (Galicia, Spain), and following Austin methodology. In addition, the relationships amongst Sn, Ta and Nb content, as metals of interest, the specific rate of breakage S-i, the kinetic parameters, and the operational conditions were studied through X-Ray fluorescence (XRF) techniques. The results show that, overall, the specific rate of breakage S-i decreases with decreasing feed particle size and increasing ball size for most of the tested conditions. A selection function, alpha(T), was formulated on the basis of the ball size for both Penouta mine samples. Finally, it was found that there does exist a direct relationship amongst Sn, Ta and Nb content, as metals of interest, in the milling product, the specific rate of breakage S-i and the operational-mineralogical variables of ball size, mill speed and feed particle size.