A combined grinding media charge model is proposed for commercial tumbling mills composed of grinding bodies of two shapes — conventional balls of the same diameter and cubes having concave faces with radius of curvature being close to balls' radius of curvature. Cubes faces dimension is equal to half of balls diameter, number of cubes and balls is the same. It is shown, that in drum mill rotation, the described mix of balls and cubes acquires a densest face-centered packing, in which cubes are interspaced with balls. With that, in contrast to point contact of conventional balls charge, mix in question provides for predominately surface areal contact of grinding bodies, significantly increasing abrasive effect upon milled ore, contributing to noticeable intensification of fine grind, increasing mills specific output with respect to product fine size fractions, decreasing specific energy consumption in grinding and also improving results of subsequent flotation or magnetic processing stages.

1. Razumov K. A. Gornyi Zhurnal — Mining Journal, 1947, no 3, pp. 31–35.

2. Inventor's certificate 948438, USSR.