ASSUMPTIONS FOR MODELING NITROGEN BIOFERTILIZER GRANULATION

Nitrogen fertilizers, especially urea, are widely used to increase crop yield and ensure optimal plant growth conditions. Enough nitrogen positively influences harvest quality, enhances plant resistance to diseases and environmental factors such as temperature fluctuations [1]. However, despite its agronomic advantages, the use of nitrogen fertilizers raises environmental concerns. Due to leaching, nitrogen compounds, particularly nitrates, can infiltrate groundwater, promoting eutrophication and degrading soil quality [2]. To reduce the negative impact, innovative solutions are being explored, including the incorporation of bioactive substances into fertilizer. One such substance is algae, which act as natural bio-stimulants. Algae stimulate plant growth, enhance nutrient uptake [3]. Granular fertilizers are usually produced and used. Granulation can be performed using various methods, with wet granulation being one of the most effective, typically carried out with a drum granulator. During this process, granules form through primary particle agglomeration, progressing to fully developed and stabilized granules. As granulation is a multi-stage and complex process, its optimization in industrial applications is crucial [4]. Due to the complexity of the granulation process, mathematical models are increasingly used in the industry to optimize production conditions and reduce the number of experimental trials. One of the modelling techniques is the Discrete Element Method (DEM), which enables the analysis of individual particle interactions and the prediction of granule formation [5]. However, to successfully implement DEM modelling, it is essential to collect accurate data on particle properties. Therefore, in this work, to model the granulation process of crystalline urea and algae, experimental granulation was performed and the following mechanical and physical characteristics were investigated: inter-particle adhesion forces, friction coefficients, angle of refraction etc.