XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3689
..23
.
tanb
P
e
0 255 11
11.23 0.30 3
15
0.30 3 97 9.4
.9
.7
.23/6.25h
gross
x11
2
0
2
#
###
####
=
+
-
b6.25
^0.30 ^0.05 h
ll
The calculation of charge density ρc =3.97 is an exercise for
the reader using equation (4) of this paper.
,P 16 228 kW
gross =
So, a combination of 16% ball load, 30% total load, and
9.4 rpm is suitable for drawing around 16 MW.
The actual data taken from the PI system shows the
averages for one shift of 12 hours as shown in Figure 5:
In conclusion, the calculated values were very close to
the operating values.
CONCLUSIONS
The proposed mathematical model has a normal distribu-
tion about the mean with the same form for grate and over-
flow discharge mills, such as SAG, AG and Ball Mills. The
only difference is the coefficient depending on the type of
discharge mechanism.
The proposed model has been proven with a wide set
of industrial data, which has a standard deviation of 4.7%
giving a precision of ±9.2% for 95% confidence level.
The grate discharge mills consume more power than the
overflow discharge mills. This value is around 15%, which
is very close to that proposed by Bond in equation (1).
Mills of high aspect ratio (D/L) consume more power
than mills of low aspect ratio.
The contribution of conical mill ends to the power
draw vary from 0 to 12%, depending on mill dimensions,
total load, and cone angle.
REFERENCES
Austin, L. (1990). ‘A mill power equation for SAG mills’.
Minerals &Metallurgical Processing, USA.
Austin, L. &F. Concha (1994). ‘Diseño y Simulación de
Circuitos de Molienda y Clasificación’. CYTEC, Chile.
Figure 5. PI data versus calculated power
..23
.
tanb
P
e
0 255 11
11.23 0.30 3
15
0.30 3 97 9.4
.9
.7
.23/6.25h
gross
x11
2
0
2
#
###
####
=
+
-
b6.25
^0.30 ^0.05 h
ll
The calculation of charge density ρc =3.97 is an exercise for
the reader using equation (4) of this paper.
,P 16 228 kW
gross =
So, a combination of 16% ball load, 30% total load, and
9.4 rpm is suitable for drawing around 16 MW.
The actual data taken from the PI system shows the
averages for one shift of 12 hours as shown in Figure 5:
In conclusion, the calculated values were very close to
the operating values.
CONCLUSIONS
The proposed mathematical model has a normal distribu-
tion about the mean with the same form for grate and over-
flow discharge mills, such as SAG, AG and Ball Mills. The
only difference is the coefficient depending on the type of
discharge mechanism.
The proposed model has been proven with a wide set
of industrial data, which has a standard deviation of 4.7%
giving a precision of ±9.2% for 95% confidence level.
The grate discharge mills consume more power than the
overflow discharge mills. This value is around 15%, which
is very close to that proposed by Bond in equation (1).
Mills of high aspect ratio (D/L) consume more power
than mills of low aspect ratio.
The contribution of conical mill ends to the power
draw vary from 0 to 12%, depending on mill dimensions,
total load, and cone angle.
REFERENCES
Austin, L. (1990). ‘A mill power equation for SAG mills’.
Minerals &Metallurgical Processing, USA.
Austin, L. &F. Concha (1994). ‘Diseño y Simulación de
Circuitos de Molienda y Clasificación’. CYTEC, Chile.
Figure 5. PI data versus calculated power