Development of a mathematical model for simulation of coal crushing in a Hammer mill

Using the basic size-mass balance size reduction model for a continuous crushing operation and invoking the concept of a perfectly mixed system, a mathematical relationship has been obtained between the feed and product size distributions for a hammer mill. The model parameters ‘breakage distribution function’ for different size fractions of a Prime Coking Coal and an imported coal were determined by conducting appropriate tests in a laboratory hammer mill. Using data generated in the Rourkela Steel Plant on a Production hammer mill, variation of the second set of model parameters, ‘absolute rate of breakage of particles of each size class’, with coal feed rate to the mill was established. Analysis of the data generated in the plant has shown that only +10 mm particles of the imported coal broke faster than the PCC particles of the same size. The developed mathematical model can be used to stimulate the performance of the crushing plant in respect of the effect of feed size distribution and feed rate, and for taking control action for keeping the product fineness constant by adjusting the coal feed rate to the hammer mill