Scale up and simulation of Vertimill™ pilot test operated with copper ore

Vertimill™ has been used in regrind circuits during the past years due to its greater efficiency when compared to the conventional tube ball mill. This paper presents the Vertimill™ pilot grinding tests with a sample of copper ore carried out in closed circuit with a high frequency screen. The sample was crushed 100% to <6 mm. All operating variables were measured under controlled conditions to produce a mass balance of the test. A laboratory batch ball mill was used to characterize the sample in order to determine the energy specific selection function and the breakage function. Previous studies have shown that the Vertimill™ produces larger values of the selection function and a constant scaling factor can be used to simulate the product particle size distribution of the Vertimill™ from the batch ball mill grinding tests. The results of the simulations showed that it is possible to estimate the product particle size distribution of the Vertimill™ pilot scale from breakage parameters determined from a lab-scale batch ball mill. These results confirm that the Vertimill™ and the conventional ball mill use similar mechanisms of impact and that the main difference between them is the intensity and frequency of the impacts.