XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 187
the different fractions was determined using a digital weigh
scale attachable to cranes (Steinberg SBS-KW-3/1K) to
produce cumulative particle size distribution (PSD) curves.
Further, the content of valuable material in each frac-
tion was quantified. Therefore, the 11 smaller fractions
were further crushed (jaw crusher → flat face double roll
crusher → oscillating disc mill) and split as required to
finally obtain 3 samples at 20 g of each size fraction for
x-ray fluorescence (XRF) analyses of the chemical com-
position of the fractions, see also (Villarroel und Jenkner
2019). The samples were analyzed on an XRF spectrometer
(Panalytical Axios) at the Helmholtz-Institute Freiberg for
Resource Technology (HIF). The amount of material in the
+31.5 mm fraction did not meet the requirements of the
minimum sample mass acc. to (Gy 1955). Therefore, this
fraction was not further considered.
RESULTS
Particle Size Distribution
For feed particle size 10/30 mm and 30/60 mm similar
trends could be observed with regard to the influence of the
crushing gap size relative to the feed particle size. On the
other side, the particle size dependency, which was to be
expected acc. to eq. (1) could not be confirmed. There was
no significant difference in size reduction ratios between the
10/30 mm fraction and the 30/60 mm fraction. The reason
could be, that contrary to the vertical shaft impact crushers
(VSI) where the particle leaves the crushing chamber typi-
cally being stressed once, the particle in the HSI is stressed
multiple times before discharged. That is, why in the fol-
lowing only the two tests HAM18, PB-006 an HAM18,
PB-016 with the same feed particle size of 10/30 mm and
a crushing gap of 60 mm and 15 mm shall be discussed in
greater detail with references made to other tests wherever
necessary.
The particle size distribution curves are shown in
Figure 7. Obviously, the width of the crushing gap has a
major impact on the cumulative PSD curves if the crush-
ing gap is smaller than the maximum feed particle size (test
HAM18, PB-006). If the crushing gap is equal or larger
than the largest particle size, there is still an influence of
the comminution process visible in the finer fractions
while in the larger fractions the curves almost coincide (test
HAM18, PB-016). Similar trends could be observed when-
ever the crushing gap was equal or larger than the upper
limit of the feed size (i.e., HAM18, PB-001, HAM18,
PB-010 and HAM18, PB-012).
In a next step, the chemical content of each fraction
was analyzed. Table 4 shows exemplary the results of test
Figure 7. PSD of feed and product as a function of crushing gap and throughput (blue -feed size
fraction 10/30 mm, green—product PSD at 60 mm gap, red—product PSD at 15 mm gap)
the different fractions was determined using a digital weigh
scale attachable to cranes (Steinberg SBS-KW-3/1K) to
produce cumulative particle size distribution (PSD) curves.
Further, the content of valuable material in each frac-
tion was quantified. Therefore, the 11 smaller fractions
were further crushed (jaw crusher → flat face double roll
crusher → oscillating disc mill) and split as required to
finally obtain 3 samples at 20 g of each size fraction for
x-ray fluorescence (XRF) analyses of the chemical com-
position of the fractions, see also (Villarroel und Jenkner
2019). The samples were analyzed on an XRF spectrometer
(Panalytical Axios) at the Helmholtz-Institute Freiberg for
Resource Technology (HIF). The amount of material in the
+31.5 mm fraction did not meet the requirements of the
minimum sample mass acc. to (Gy 1955). Therefore, this
fraction was not further considered.
RESULTS
Particle Size Distribution
For feed particle size 10/30 mm and 30/60 mm similar
trends could be observed with regard to the influence of the
crushing gap size relative to the feed particle size. On the
other side, the particle size dependency, which was to be
expected acc. to eq. (1) could not be confirmed. There was
no significant difference in size reduction ratios between the
10/30 mm fraction and the 30/60 mm fraction. The reason
could be, that contrary to the vertical shaft impact crushers
(VSI) where the particle leaves the crushing chamber typi-
cally being stressed once, the particle in the HSI is stressed
multiple times before discharged. That is, why in the fol-
lowing only the two tests HAM18, PB-006 an HAM18,
PB-016 with the same feed particle size of 10/30 mm and
a crushing gap of 60 mm and 15 mm shall be discussed in
greater detail with references made to other tests wherever
necessary.
The particle size distribution curves are shown in
Figure 7. Obviously, the width of the crushing gap has a
major impact on the cumulative PSD curves if the crush-
ing gap is smaller than the maximum feed particle size (test
HAM18, PB-006). If the crushing gap is equal or larger
than the largest particle size, there is still an influence of
the comminution process visible in the finer fractions
while in the larger fractions the curves almost coincide (test
HAM18, PB-016). Similar trends could be observed when-
ever the crushing gap was equal or larger than the upper
limit of the feed size (i.e., HAM18, PB-001, HAM18,
PB-010 and HAM18, PB-012).
In a next step, the chemical content of each fraction
was analyzed. Table 4 shows exemplary the results of test
Figure 7. PSD of feed and product as a function of crushing gap and throughput (blue -feed size
fraction 10/30 mm, green—product PSD at 60 mm gap, red—product PSD at 15 mm gap)