Since October 2003, the BHP Billiton Cannington mill has operated a grinding circuit consisting of an AG mill, pebble crusher and a Vertimill®which in this paper will be referred to as an AVC circuit. What is unique about this circuit is that it utilizes a Vertimill® for secondary grinding rather than the conventional ball mill. The implementation of this new circuit design was based on Cannington’s positive experience with Vertimill® technology as well as results from modelling and simulation studies. A number of complete grinding circuit surveys were carried out in order to assess the performance of the existing circuit and to evaluate circuit expansion and optimisation options. The surveys and operating data collected confirmed the exceptional grinding energy efficiency achievable using the AVC circuit. Further improvement in plant performance is expected following the installation of an online particle size analyser and an OCS expert system for process control.