12 Property Function to Compute the Dustiness of Powders
421
from Durcal40. Particle size distribution of the ground powders was investigated by
means of a HELOS laser light diffraction spectrometer made by Sympatec GmbH,
Germany, and a Horiba LA 950 laser light diffraction particle size analyzer made
by Retsch Technology, Germany. Dustiness of the ground powders was investigated
with a single drop apparatus (Sect. 3.2.1) and the UNC dustiness tester (Sect. 3.2.3).
Since dry powders were characterized in dustiness investigation, the measurement
with the HELOS system was carried out as dry measurement. Therefore the HELOS
diffraction spectrometer was coupled with a RODOS dry dispersion unit made by
Sympatec, and a dispersion pressure of 2 bar was set. For comparison wet dispersion
measurements were made with the Horiba LA 950. Results of both measurements
are shown in Figs. 9 and 10.
It should be noted, that in dry particle size analysis, tightly bound agglomerate
structures are actual depicted as primary particles, since dry dispersion in the air
stream is usually insufficient for complete digestion of the agglomerates in this
particle size range. However, the particle sizes obtained with the HELOS system
will more realistically represent the conditions in the single drop apparatus as well
Fig. 9 Particle distribution
density by mass of dry
dispersion measurement with
HELOS/RODOS
combination for reference
grinding and grinding with
different grinding aids
Fig. 10 Particle distribution
density by mass of wet
dispersion measurement with
Horiba LA 950 for reference
grinding and grinding with
different grinding aids
421
from Durcal40. Particle size distribution of the ground powders was investigated by
means of a HELOS laser light diffraction spectrometer made by Sympatec GmbH,
Germany, and a Horiba LA 950 laser light diffraction particle size analyzer made
by Retsch Technology, Germany. Dustiness of the ground powders was investigated
with a single drop apparatus (Sect. 3.2.1) and the UNC dustiness tester (Sect. 3.2.3).
Since dry powders were characterized in dustiness investigation, the measurement
with the HELOS system was carried out as dry measurement. Therefore the HELOS
diffraction spectrometer was coupled with a RODOS dry dispersion unit made by
Sympatec, and a dispersion pressure of 2 bar was set. For comparison wet dispersion
measurements were made with the Horiba LA 950. Results of both measurements
are shown in Figs. 9 and 10.
It should be noted, that in dry particle size analysis, tightly bound agglomerate
structures are actual depicted as primary particles, since dry dispersion in the air
stream is usually insufficient for complete digestion of the agglomerates in this
particle size range. However, the particle sizes obtained with the HELOS system
will more realistically represent the conditions in the single drop apparatus as well
Fig. 9 Particle distribution
density by mass of dry
dispersion measurement with
HELOS/RODOS
combination for reference
grinding and grinding with
different grinding aids
Fig. 10 Particle distribution
density by mass of wet
dispersion measurement with
Horiba LA 950 for reference
grinding and grinding with
different grinding aids