Strength properties of grains have a significant impact on the energy demand of grinding mills. This paper presents the results of tests of strength and energy needed the for destruction of rice grains. The research aim was to experimentally determine mechanical and processing properties of the rice grains. The research problem was formulated in the form of questions: (1) what force and energy are needed to induce a rupture of rice grain of the Oryza sativa L. of long-grain variety? (2) what is the relationship between grain size and strength parameters and the energy of grinding rice grain of the species Oryza sativa L. long-grain variety? In order to find the answer to the problems posed, a static compression test of rice grains was done. The results indicate that the average forces needed to crush rice grain are 174.99 kg m·s−2, and the average energy is 28.03 mJ. There was no statistically significant relationship between the grain volume calculated based on the volumetric mass density Vρ and the crushing energy, nor between the volume Vρ and other strength properties of rice grains. In the case of Vs, a low negative correlation between strength σmin and a low positive correlation between the power inducing the first crack were found for the grain size related volume. A low negative correlation between the grain thickness a3, stresses σmin and work WFmax was found as well as a low positive correlation between thickness a3 and the force inducing the first crack Fmin.
Mechanical and Processing Properties of Rice Grains
