Article
Process Behavior and Product Quality in Fertilizer
Manufacturing Using Continuous Hopper Transfer Pan
Granulation—Experimental Investigations
Mateusz Przywara
1,
* , Robert Dürr
2
, Eric Otto
3
, Achim Kienle
2,3
and Dorota Antos
1
Citation: Przywara, M.; Dürr, R.;
Otto, E.; Kienle, A.; Antos, D. Process
Behavior and Product Quality in
Fertilizer Manufacturing Using
Continuous Hopper Transfer Pan
Granulation—Experimental
Investigations. Processes 2021, 9, 1439.
https://doi.org/10.3390/pr9081439
Academic Editor: Arkadiusz Gola
Received: 15 July 2021
Accepted: 16 August 2021
Published: 19 August 2021
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4.0/).
1
Department of Chemical and Process Engineering, Rzeszów University of Technology,
Powsta´nców Warszawy 12, 35-959 Rzeszów, Poland; dorota.antos@prz.edu.pl
2
Process Synthesis and Process Dynamics, Max-Planck-Institute for Complex Technical Dynamics,
D-39106 Magdeburg, Germany; duerr@mpi-magdeburg.mpg.de (R.D.);
kienle@mpi-magdeburg.mpg.de (A.K.)
3
Chair for Automation/Modeling, Otto-von-Guericke-University, Universitätsplatz 2,
D-39106 Magdeburg, Germany; eric.otto@ovgu.de
* Correspondence: m.przywara@prz.edu.pl; Tel.: +48-178-651-737
Abstract:
Fertilizers are commonly used to improve the soil quality in both conventional and organic
agriculture. One such fertilizer is dolomite for which soil application in granulated form is advanta-
geous. These granules are commonly produced from ground dolomite powder in continuous pan
transfer granulators. During production, the granulator’s operation parameters affect the granules’
properties and thereby also the overall performance of the fertilizer. To ensure product granules of cer-
tain specifications and an efficient overall production, process control and intensification approaches
based on mathematical models can be applied. However, the latter require high-quality quantitative
experimental data describing the effects of process operation parameters on the granule properties.
Therefore, in this article, such data is presented for a lab-scale experimental setup. Investigations
were carried out into how variations in binder spray rate, binder composition, feed powder flow
rate, pan inclination angle, and angular velocity affect particle size distribution, mechanical stability,
and humidity. Furthermore, in contrast to existing work samples from both, pan granules and
product granules are analyzed. The influence of operation parameter variations on the differences
between both, also known as trajectory separation, is described quantitatively. The results obtained
indicate an increase in the average particle size with increasing binder flow rate to feed rate and
increasing binder concentration and the inclination angle of the pan. Compressive strength varied
significantly depending on the operating parameters. Significant differences in properties were
observed for the product and the intermediate (pan) samples. In fact, for some operation parameters,
e.g., binder feed rate, the magnitude of the separation effect strongly depends on the specific value of
the operation parameter. The presented concise data will enable future mathematical modeling of
the pan granulation process, e.g., using the framework of population balance equations.
Keywords: pan granulation; continuous operation; granulation; granule properties
1. Introduction
Fertilizers, plant protection products, and soil conditioners of natural origin are
increasingly used in both conventional and organic agriculture. The widespread and
often excessive use of fertilizers results in progressive soil acidification and consequently
reduces the yield and quality of crop production. Acid rains additionally contribute to
soil degradation [
1
–
3
]. Under these circumstances, the use of commercially available
magnesium-calcium fertilizers for deacidification purposes is no longer sufficient, and
enrichment with suitable trace elements is required. One such fertilizer is dolomite, which
in powder form, after grinding, acts as a fertilizer providing magnesium and calcium to
Processes 2021, 9, 1439. https://doi.org/10.3390/pr9081439 https://www.mdpi.com/journal/processes
