This paper investigates grinding of mineral mixtures with different grindabilities in the Bond ball mill. Understanding the ore mixture grinding is of great importance in mineral processing. The energy required for crushing and grinding is presented by the Bond work index and is determined by means of Bond grindability test. This paper presents the experimental results of the Bond work index values obtained by the standard method on limestone and andesite samples, as well as composite samples made up from these ore in different weight ratios. Comparatively are shown the Bond work index values that are obtained by the mass fraction of components that make up the composite samples calculation and their differences from the real value. During the Bond work index value determining, changes in the composition of the grinding products and circulating mill charge were monitored.