3758 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
The results from the calibration run are shown in
Figure 2. The graphs present the time dependency of the
discharge rates, hold-ups in the pans and the flow rates
through the grates inwards and outwards for both solids
and water.
The first graph on the top-left shows the discharge rates
(solid lines) and the audit data (dotted lines). The results
from the simulations are very close to the plant data and
has required several attempts before reaching that good fit.
The second plot on the top-right presents the mass of solids
and water recirculated in the pans. It can be easily noticed
that the amount of solids recirculated in the pans is larger
than the one for the water. Also, both plots have reached
a plateau after 35 seconds (which corresponds to almost
6 revolutions of the mill) meaning that the simulation
has reached the steady state. An efficient discharge system
should have these two lines as low as possible. Even more,
a higher recirculation of the solids and water in pans will
increase the wear of the lifters and pans reducing the life of
the discharge system.
The last two plots at the bottom show the flow rates
through the grates in both directions inwards (from pans
back into the mill) and outwards (from inside the mill into
the pans). Both plots also show a peak in the discharge rates
outwards right after 5 seconds which corresponds to the
moment when the grates are opened numerically. The dif-
ference between the blue and red lines in these two plots
represents the net transport of the solids and water through
the grates. A good discharge system should have a net
transport as large as possible and even more important the
inwards flow rate as lower as possible. Table 2 summarize
the results presented in Figure 2.
0%
10%
20%
30%
40%
50%
60%
0
500
1000
1500
2000
2500
3000
0 5 10 15 20 25 30 35 40
Time (sec)
Calibration run, Discharge flowrates
Solids Water Solids Audit
Water audit %Filling Slice
0
1000
2000
3000
4000
5000
6000
7000
0 10 20 30 40
Time (sec)
Calibration Run -Hold-ups in pans
Solids mass pans
Water mass pan
0
1000
2000
3000
4000
5000
6000
0 5 10 15 20 25 30 35 40
Time (sec)
Calibration Run -Grate flowrates for Solids
Solids Flow Grates -Outwards
Solids Flow Grates -Inwards
0
500
1000
1500
2000
2500
3000
0 5 10 15 20 25 30 35 40
Time (sec)
Calibration Run -Grate flowrates for Water
Water Flow Grates -Outwards
Water Flow Grates -Inwards
Figure 2. Simulation results from the calibration run
Table 2. Audit data and the simulation results from the calibration run
Discharge Rates Hold-up Net transport
Solids Audit
(t/h)
Solids Sim
(t/h)
Water Audit
(m3/h)
Water Sim
(m3/h)
Solids
(kg)
Water
(kg)
Solids
(t/h)
Water
(m3/h)
1,056 1,092 330 311 5,511 682 1,098 310
Slice
Filling
%Massflowrate
(t/h)
Solids
and
water
holdupin
pans
(kg)
Massflowrate
(t/h)
Flowrate
(t/h)
The results from the calibration run are shown in
Figure 2. The graphs present the time dependency of the
discharge rates, hold-ups in the pans and the flow rates
through the grates inwards and outwards for both solids
and water.
The first graph on the top-left shows the discharge rates
(solid lines) and the audit data (dotted lines). The results
from the simulations are very close to the plant data and
has required several attempts before reaching that good fit.
The second plot on the top-right presents the mass of solids
and water recirculated in the pans. It can be easily noticed
that the amount of solids recirculated in the pans is larger
than the one for the water. Also, both plots have reached
a plateau after 35 seconds (which corresponds to almost
6 revolutions of the mill) meaning that the simulation
has reached the steady state. An efficient discharge system
should have these two lines as low as possible. Even more,
a higher recirculation of the solids and water in pans will
increase the wear of the lifters and pans reducing the life of
the discharge system.
The last two plots at the bottom show the flow rates
through the grates in both directions inwards (from pans
back into the mill) and outwards (from inside the mill into
the pans). Both plots also show a peak in the discharge rates
outwards right after 5 seconds which corresponds to the
moment when the grates are opened numerically. The dif-
ference between the blue and red lines in these two plots
represents the net transport of the solids and water through
the grates. A good discharge system should have a net
transport as large as possible and even more important the
inwards flow rate as lower as possible. Table 2 summarize
the results presented in Figure 2.
0%
10%
20%
30%
40%
50%
60%
0
500
1000
1500
2000
2500
3000
0 5 10 15 20 25 30 35 40
Time (sec)
Calibration run, Discharge flowrates
Solids Water Solids Audit
Water audit %Filling Slice
0
1000
2000
3000
4000
5000
6000
7000
0 10 20 30 40
Time (sec)
Calibration Run -Hold-ups in pans
Solids mass pans
Water mass pan
0
1000
2000
3000
4000
5000
6000
0 5 10 15 20 25 30 35 40
Time (sec)
Calibration Run -Grate flowrates for Solids
Solids Flow Grates -Outwards
Solids Flow Grates -Inwards
0
500
1000
1500
2000
2500
3000
0 5 10 15 20 25 30 35 40
Time (sec)
Calibration Run -Grate flowrates for Water
Water Flow Grates -Outwards
Water Flow Grates -Inwards
Figure 2. Simulation results from the calibration run
Table 2. Audit data and the simulation results from the calibration run
Discharge Rates Hold-up Net transport
Solids Audit
(t/h)
Solids Sim
(t/h)
Water Audit
(m3/h)
Water Sim
(m3/h)
Solids
(kg)
Water
(kg)
Solids
(t/h)
Water
(m3/h)
1,056 1,092 330 311 5,511 682 1,098 310
Slice
Filling
%Massflowrate
(t/h)
Solids
and
water
holdupin
pans
(kg)
Massflowrate
(t/h)
Flowrate
(t/h)