Rotating drums are commonly used as grinders by inserting balls or rods into the drum. They are also employed as a standard measurement device for attrition and friability, mainly in the pharmaceutical industry. This paper presents a phenomenological study of the behavior of rotating drums and the fatigue phenomenon. A sensitivity test showed that for potash the drum should rotate at 30 rpm and the sample weight should be 100 g, so as to maximize the attrition rate. Further experimentation showed that the crush strength of the surviving particles changes significantly during the test owing to fatigue.