Single-particle breakage tests of South Blackwater and Ensham coal were conducted by using a computer-monitored twin-pendulum device to determine a parameter which will describe the product size distribution of the breakage product. The size distribution parameter' t50' related to the specific comminution energy [defined as the comminution energy per unit mass which transmitted to a particle during breakage (kWh/t)] of breakage coal particles and described the breakage characteristics of two types of coal. At a specific comminution energy level, the t50 parameter of South Blackwater coal was higher than the t50 parameter of Ensham coal. A degradation model was developed with several parameters for the coal-handling circuits of Gladstone Port. In the degradation model, the raw data of the non-cushioned curve deviates from the model data after a few initial drops because the mass of the sample reduces in successive drops and produced more fines.