In previous years the experimental set-up was about granules composed of only two
phases, a particle phase and a binder phase. The particle phase consisted of insoluble
limestone particles with different particle size distributions. The particle size distribution
was varied systematically by changing the ratio of coarse to fine primary particles. It was
found that the composition of primary particles plays an important role for the granule
properties, especially the amount and distribution of coarse primary particles.
The aim of this years project was to amplify the knowledge about structure - functionality
correlation. Therefore a set of experiments with two different primary particle phases
was investigated. The materials were chosen to have a soluble and an insoluble particle
phase. As soluble particle phase sodium chloride was chosen because it allows the
measurement of conductivity during dissolution. The insoluble particle phase was again
chosen to be limestone. Also the binder was hold constant to be polyethylene glycol but
it was now used in a melted state and not in concentrated solution as before.
Additionally the granulation method was changed into a two step method involving casting
and milling. This step was necessary because it was aimed to generate a random
close structure of primary particles in binder. In more detail a mixture of primary particles
was mixed with melted binder and casted on a plate for cooling. The amount of binder
was adapted to generate a saturated system without porosity. Afterwards the hardened
plate was milled down to the desired granule size between 250 and 710m.
The granules were investigated in two ways as done in previous work. The structure
was determined from X-ray micro-tomography images calculating structure measures like
chord length distribution, covariance function and star volume of different phases. The
granule properties were determined by different measurements including single particle
crushing and dissolution behavior.
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