Ore breakage characterisation plays an essential role in the design and optimization of comminution circuits. Recently, the JKMRC comminution research team has developed a Rotary Breakage Tester (JKRBT) for rapid particle breakage characterisation tests. The JKRBT uses a rotor-stator impacting system, in which particles gain a controlled kinetic energy while they are spun in the rotor and are then ejected and impacted against the stator, causing particle breakage. The first industrialised JKRBT was installed at Anglo Research in Johannesburg in March 2007, and six more JKRBTs were deployed in 2008 around the world. This paper discusses the major design and calibration issues encountered in the JKRBT development and findings from detailed experimental studies. (C) 2009 Elsevier Ltd. All rights reserved.