Modelling of a continuous maize milling process under the discrete element method

CHIARAVALLE, ALEJANDRO GABRIEL; LOBOS DE PONGA, JAQUELINA; PIÑA, JULIANA; COTABARREN, IVANA M.

Buenos Aires

Congreso; 11th World Congress of Chemical Engineering; 2023

This work explores the first attempts into modeling maize continuous milling in hammer mills by the Discrete Element Method (DEM), employing a particle replacement model fitted to experimental data to represent particle breakage. Prior to the simulations, a complete set of experimental tests were carried out in order to understand the milling process as a function of operating variables. A Perten 120 laboratory-scale hammer mill was used for gathering the experimental data. Three different orifice aperture screens (1, 2 and 4 mm) were tested against three continuous flowrates into the milling chamber (100, 200 and 400 g/min). The product particle size distribution (PSD) was analyzed and power draw was measured for each test. The system was modelled in the DEM environment. Simulations were run using Rocky DEM (ANSYS). Experimental milling tests showed an increase in power draw with both increasing flowrate and decreasing screen aperture. High mass flowrates drew the product’s PSD to finer sizes only when using the 1 mm screen, whereas the PSD for the 2 mm and 4 mm screens did not change with increasing flowrate. Two simulations of 2 seconds of operation were run, testing the 100 g/min flowrate and 4 mm screen aperture setup and evaluating the effect of the breakage model’s fragmentation parameters. The model was able to properly simulate the PSD of grinded maize, leaving out the finest sizes. Further work contemplates the simulation of the remaining experimental setups for fully validating the model’s prediction capabilities