Influence of the composition and agglomeration pressure on the compaction level of the fertilizers based on biomass ash and digestate

University of Agriculture in Krakow, Faculty of Production and Power Engineering 120 Balicka street, 30-149 Krakow, Poland

^* Corresponding author: marek.wrobel@urk.edu.pl

Abstract

The paper presents the results of research aimed at determining the influence of the composition of the fertilizer mixtures and the compaction pressure on the specific density and density index of fertilizer granules. Investigated mixtures were prepared from fly ash from power plant fuelled by biomass and digestate from biogas plant. The urea, sulfur and phosphorite were also added as enhancing additives. For granule samples made on a strength machine, their specific density was determined on a quasifluid-pycnometer. To determine the effect of agglomerate pressure on the compaction process, the absolute density of the materials was omitted. In such case it was needed to introduce a density index A_I. Such a presentation of the results obtained has made it possible to clearly determine how the density of the test mixture results in the applied agglomeration pressure. The specific density of the resulting granules was in the range of 0.85-1.27 g/cm³. The determined density index for the given pressure was in the following ranges: 0.44-0.49 g/cm³ (pressure 100MPa), 0.47-0.51 g/cm³ (pressure 150MPa) 0.51 - 0.59 g/cm³ (200MPa pressure). This means that, regardless of the contribution of components to the mixture at the given pressure, a similar degree of compaction was obtained.