In mineral processing, ore grinding is an energy-intensive process. Tumbling mills used in grinding processes can be accounted for as rotating drums with liners. As part of an effort to evaluate ways of reducing energy consumption in such systems, therefore, particulate flows in rotating drums are studied in this work. More specifically, using a new DEM tool, which is one of the modules of a larger in-house computational package called CFLOWSS, particulate flows in rotating drums are qualitatively and quantitatively analyzed. The results from such analyses are compared with experimental ones and other numerical results obtained using a commercial DEM software. In qualitative terms, the CFLOWSS results show a relatively good agreement with experimental photographs previously taken in a laboratory. In quantitative terms, in turn, the CFLOWSS predictions show a strong correspondence with those ones made by the commercial software. For instance, the relative discrepancies of the boxplots’ medians associated with the number of contacts, power, and forces predicted by both (in-house and commercial) tools present values smaller than 8%. At a 60 RPM drum rotation velocity, indeed, the number of contacts related discrepancies reach values as low as 0.8%. Some of the contributions of this work involve (i) the development of a new DEM tool capable of realistically describing particulate flows in rotating drums, and (ii) the use of statistical treatments to quantitatively analyze DEM results. This last aspect is important because this sort of assessments provides an improved way to analyze the behavior of particulate flows.