Simulation of the microalgae-enriched nitrogen fertilizer granulation mechanism using the DEM method

Abstract

The use of granular fertilizers offers significant advantages over traditional powder forms, including improved nutrient distribution, reduced dust, and controlled nutrient release. These benefits enhance plant growth while minimizing negative environmental impacts. The addition of reused materials (recycle) significantly influences the size distribution and strength of granular fertilizers. It was determined that incorporating 60% recycle increases the part of commercial granules (size 2.0–4.0 mm) from 22% to about 68%. However, this increase is accompanied by a decrease in static strength, which drops from 2.8–3.8 MPa to 1.7–2.3 MPa. Modelling granulation processes holds substantial potential for the fertilizer industry, enabling the optimization of high-quality granular fertilizer production while minimizing the need for extensive experimental trials. This approach not only streamlines manufacturing but also ensures consistent nutrient supply, ultimately contributing to improved crop yields and sustainable agricultural practices. In this study, a simulation model based on an actual granulation drum was used to investigate the granulation process of a mixture containing recycled material, crystalline urea, and the microalgae Chlorella vulgaris sp. The granulation simulation data showed that granule formation began within 30 seconds and that the desired quantity of the mixture was produced in just 30 seconds. Throughout the process, the segregation coefficient remained near zero, indicating effective granule formation and distribution.