Modeling and simulation of My comminution process are based on the two mechanistic-phenomenological concepts, namely the breakage function or the breakage distribution function and the selection function or the breakage rate function. For a realistic and mathematical representation of any grinding process, the characteristics of these functions with respect to the operational variables of a given comminution system are the prime requisite. For the present work, the effect of the three major operating variables of a circular fluid energy mill, namely the grinding nozzle pressure, grinding nozzle size and the material feed rate on the breakage distribution parameter of the milli were analysed using G-H solution for the size-discretised batch grinding equation. The parameter values were estimated for four grinding nozzle pressures, four grinding nozzle sizes and four material feed rates using the ground product size distribution after each pass, for six successive passes through the grinding chamber of a circular fluid energy mill. The parameter values could be related to particle size with the sum of two power functions equation. The behaviour of the coefficients of these equations were analysed and characterised with respect to the operating variables.