2 Advanced mill modelling prior to DEM The first attempts in coupling impact energy information to particle breakage data to predict grinding have been made in the late 1980s and early 1990s These were used to predict the functions that make up the traditional population balance model The greatest difficulty at the time 2 Advanced mill modelling prior to DEM The first attempts in coupling impact energy information to particle breakage data to predict grinding have been made in the late 1980s and early 1990s These were used to predict the functions that make up the traditional population balance model The greatest difficulty at the time