A semi-autogenous (SAG) or autogenous mills (AG) circuit commonly comprises a pebble (cone) crusher to deal with the critical size particles. The pebbles crusher is often oversized, and thus not fully utilized. The hypothesis put forward in this paper is that active control of the cone crusher's eccentric speed and closed side setting (CSS) can increase throughput and/or energy efficiency of the SAG circuit. To verify this hypothesis, a dynamic model of a SAG mill-pebble crusher circuit was implemented. The dynamic unit models are based on results presented by several different researchers, whose results here have been combined and implemented in Matlab/Simulink. Previous research shows that by controlling the cone crusher operational parameters, the product particle size distribution (PSD) can be altered during operation. However, few papers have been published about whether the changes of the pebbles crusher's product PSD, lead to a higher performance of the SAG circuit. This paper examines the relations between the SAG mill and the pebble crusher in closed circuit while putting emphasis on controlling the pebble crusher in order to optimize the circuit throughput.