Investigation of effects of organic fertilizer pellet rheological and geometric properties on mechanical strength

Abstract

The main requirement imposed on organic granulated fertilizer as a new product produced from secondary raw material is the possibility to use this product under specific operation conditions determined by environmental factors, static and dynamic loads, mechanical effects, etc. Mechanical strength is considered as the main mechanical property of granulated bulky materials. Organic compost fertilizer pellets as anisotropic materials are characterized by rheological properties, which vary in different directions inside the pellet. The study investigated rheological and strength properties of the newly developed granulated organic fertilizer pellets produced from beef cattle and poultry manure and organic waste compost. As a result, the characteristics of the mechanical properties of the new product, which are characteristic to fragile materials, were presented. Dependencies between pellet deformations and the size of the subjected load depending on the pellet geometrical parameters were determined and presented by mathematical equations with regression coefficients. Test results have shown that the limit strength in vertical and horizontal directions for organic compost pellets with the diameter of 4 mm and 6 mm, as well as for poultry manure pellet material differed from 10 % to 20 %. Pellet mechanical strength depends on their geometric parameters. Given varying deviations of pellet length from the standard sample length, pellet material strength can vary more than ± 23 %.