Coal breakage characterisation – Part 2: Multi-component breakage modelling

•A multi-component model to describe energy–size reduction for various coal particle sizes and densities.•Model parameters calibrated with JKFBC characterisation testing data.•Using tn-family of curves to determine product size distribution from the model predicted t10 parameter.•Model was validated with over 100 sets experimental data using an Australian and a Chinese coal sample. A multi-component breakage model has been developed at the Julius Kruttschnitt Mineral Research Centre (JKMRC) to describe the energy–size reduction in relation to particle size and density for coal breakage characterisation. The model takes the following form: t10=M(RD/RDmin)c·{1-exp[-fmat·x·E]}. The model incorporates four parameters and fits 60 JKFBC (JK Fine-particle Breakage Characteriser) test data for each of the Australian coal and Chinese coal samples, with R2=0.982 and 0.978 respectively. The multi-component model can be switched into a single component model by setting c=0. A set of tn-family of curves for coals ground in the JKFBC are presented. It was found that the data from various particle sizes and densities of the two coal samples, collected from the Australian and Chinese power stations, all fall on similar tn-curve trend lines. These tn-family of curves can be used in the multi-component model to estimate the product size distribution from the predicted t10 values. A procedure has been developed to calibrate the multi-component model with seven tests based on a combination of various particle sizes, coal densities and grinding energy levels, using the JKFBC device. Over 100 sets of data have been used to validate the calibration procedure.