XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3865
Data Analyzing
The various throughputs and the resulting milling energy
consumption were recorded and will be further discussed
in the following section. Figure 6 shows an example of a
typical plot of test results.
Three measured throughputs are plotted in the dia-
gram, the feed, circuit, and mill throughput. Furthermore,
the constant marks the set mill throughput, while each
of the black dashed lines marks a sampling point. The
beginning of the test is marked by slowly filling the aggre-
gates. The feed conveyor runs at maximum throughput
during this time, until the circuit throughput reaches
the set mill throughput, so an overswinging is observed.
After a certain time, the stationary point is reached, in this
case after about 2500 s. The actual measurement can be car-
ried out only after this point. For this measurement, a time
period of 10 minutes is logged and right after this period,
the sampling at the different sampling points takes place.
The sampling is conducted after the logging because other-
wise even the mass of the removed samples influences the
logged throughputs. An adequate data post processing with
determination of mean value and scatter for the recorded
throughputs are done later. This sequence is repeated three
times for most of the tests. A plot of an individual test after
data processing is shown in Figure 7. The plot also shows
the different sample identification numbers.
As shown in the diagram, the following mean values
were determined. This can be used to calculate the circula-
tion factor (U) according to (Stieß, 1997).
.79
..79
.25
U m
m
m
m m
159
1478 00 159
10
h
kg
h
kg
h
kg
feed
mill
feed
circuit feed ==
+
=
+
=
o
(1)
This factor will be used to compare the different mill-
ing parameters. In the case of wet milling, the moisture
content is deducted from circuit throughput and only the
solids circuit throughput is considered.
The same test plots are taken to calculate the specific
energy consumption and the mean value for the mechani-
cal milling power consumption of the mill is calculated.
Figure 8 shows the plot of the same test as Figure 7 with
the graphs reflecting mill power consumption and the cor-
responding feed material throughput.
An average mechanical milling power consumption of
1.43 kW is calculated. The specific energy consumption
0%
20%
40%
60%
80%
100%
0,0 1,0 2,0 3,0 4,0 5,0
Throughput in t/h
0%
20%
40%
60%
80%
100%
0% 20% 40% 60% 80% 100% 120% 140% 160%
(a)
(b)
Figure 5. Dependence of the sieving efficiency on the throughput (a) and moisture (b) according
to (Schröder et al., 2023)
Table 1. Parameter combinations done in the first milling
tests
Milling Parameter Unit Values
Milling pressure kN/m2 550 947 1408
Milling table speed m/s 0.66 1.32
Throughput kg/h 1625
Bypass
t
Bypass
t
Data Analyzing
The various throughputs and the resulting milling energy
consumption were recorded and will be further discussed
in the following section. Figure 6 shows an example of a
typical plot of test results.
Three measured throughputs are plotted in the dia-
gram, the feed, circuit, and mill throughput. Furthermore,
the constant marks the set mill throughput, while each
of the black dashed lines marks a sampling point. The
beginning of the test is marked by slowly filling the aggre-
gates. The feed conveyor runs at maximum throughput
during this time, until the circuit throughput reaches
the set mill throughput, so an overswinging is observed.
After a certain time, the stationary point is reached, in this
case after about 2500 s. The actual measurement can be car-
ried out only after this point. For this measurement, a time
period of 10 minutes is logged and right after this period,
the sampling at the different sampling points takes place.
The sampling is conducted after the logging because other-
wise even the mass of the removed samples influences the
logged throughputs. An adequate data post processing with
determination of mean value and scatter for the recorded
throughputs are done later. This sequence is repeated three
times for most of the tests. A plot of an individual test after
data processing is shown in Figure 7. The plot also shows
the different sample identification numbers.
As shown in the diagram, the following mean values
were determined. This can be used to calculate the circula-
tion factor (U) according to (Stieß, 1997).
.79
..79
.25
U m
m
m
m m
159
1478 00 159
10
h
kg
h
kg
h
kg
feed
mill
feed
circuit feed ==
+
=
+
=
o
(1)
This factor will be used to compare the different mill-
ing parameters. In the case of wet milling, the moisture
content is deducted from circuit throughput and only the
solids circuit throughput is considered.
The same test plots are taken to calculate the specific
energy consumption and the mean value for the mechani-
cal milling power consumption of the mill is calculated.
Figure 8 shows the plot of the same test as Figure 7 with
the graphs reflecting mill power consumption and the cor-
responding feed material throughput.
An average mechanical milling power consumption of
1.43 kW is calculated. The specific energy consumption
0%
20%
40%
60%
80%
100%
0,0 1,0 2,0 3,0 4,0 5,0
Throughput in t/h
0%
20%
40%
60%
80%
100%
0% 20% 40% 60% 80% 100% 120% 140% 160%
(a)
(b)
Figure 5. Dependence of the sieving efficiency on the throughput (a) and moisture (b) according
to (Schröder et al., 2023)
Table 1. Parameter combinations done in the first milling
tests
Milling Parameter Unit Values
Milling pressure kN/m2 550 947 1408
Milling table speed m/s 0.66 1.32
Throughput kg/h 1625
Bypass
t
Bypass
t