XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3741
be in another forthcoming test series), but the near identi-
cal values provided by all the tests at 100% level and above
statistically support this conclusion.
PILOT SCALE TESTING
In order to compare the performances of ball mill over-
flow discharge and ball mill grate discharge, Corem carried
out pilot testing in continuous open circuit experiments.
The tests were performed using mill with the dimensions of
0.457 m diameter and 0.914 m long. For all the test pro-
gram, the ball charge was about 30% of mill volume with a
top size of 1.5 in. Three types of discharge were tested over-
flow discharge, peripherical holes grate discharge and cen-
tral holes grate discharge end plates as shown in Figure 4
Iron concentrate was used as material for testing. The
size distribution of the feed is given in Figure 5 with a F80
of about 600 µm and a Blaine about 130 cm2/g.
The experiments were carried out varying the feed rate
(100 kg/h, 150 kg/h and 200 kg/h) and the percent solid
(65%, 70% and 75%). After stabilization, the grinding
circuit was sampled for about two hours. Two composite
samples were collected at the feed and discharge of the mill
for each condition. The samples were weighted, filtered,
and dried for particle size distribution analysis and Blaine
measurement. Operating data, electrical power, torque and
feed rate were recorded. The recording of net power shows
that the grate discharge consumed 15% to 20% more
power than the overflow discharge.
Effect of Operating Variable on Product Size
Figure 6 shows the relationship between the feed rate and
the percent solids on the product size expressed on P80.
Generally, using the grate discharge gives material finer
compared to overflow discharge. With a low feed rate the
three types of discharge give almost the same P80. Increasing
the feed rate, the grate discharge gives finer product com-
pared to the overflow discharge. Concerning the percent
solids, with a low percent solid, overflow discharge product
is finer. Increasing the percent solids, the tendency changes
and the grate discharge gives a finer product.
Figure 4. Discharge end plates
Figure 5. Feed size for overflow OF, grate 1 G1 and grate 2 G2
be in another forthcoming test series), but the near identi-
cal values provided by all the tests at 100% level and above
statistically support this conclusion.
PILOT SCALE TESTING
In order to compare the performances of ball mill over-
flow discharge and ball mill grate discharge, Corem carried
out pilot testing in continuous open circuit experiments.
The tests were performed using mill with the dimensions of
0.457 m diameter and 0.914 m long. For all the test pro-
gram, the ball charge was about 30% of mill volume with a
top size of 1.5 in. Three types of discharge were tested over-
flow discharge, peripherical holes grate discharge and cen-
tral holes grate discharge end plates as shown in Figure 4
Iron concentrate was used as material for testing. The
size distribution of the feed is given in Figure 5 with a F80
of about 600 µm and a Blaine about 130 cm2/g.
The experiments were carried out varying the feed rate
(100 kg/h, 150 kg/h and 200 kg/h) and the percent solid
(65%, 70% and 75%). After stabilization, the grinding
circuit was sampled for about two hours. Two composite
samples were collected at the feed and discharge of the mill
for each condition. The samples were weighted, filtered,
and dried for particle size distribution analysis and Blaine
measurement. Operating data, electrical power, torque and
feed rate were recorded. The recording of net power shows
that the grate discharge consumed 15% to 20% more
power than the overflow discharge.
Effect of Operating Variable on Product Size
Figure 6 shows the relationship between the feed rate and
the percent solids on the product size expressed on P80.
Generally, using the grate discharge gives material finer
compared to overflow discharge. With a low feed rate the
three types of discharge give almost the same P80. Increasing
the feed rate, the grate discharge gives finer product com-
pared to the overflow discharge. Concerning the percent
solids, with a low percent solid, overflow discharge product
is finer. Increasing the percent solids, the tendency changes
and the grate discharge gives a finer product.
Figure 4. Discharge end plates
Figure 5. Feed size for overflow OF, grate 1 G1 and grate 2 G2