3688 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
PRACTICAL CASE
A customer requires processing 2,150 tph. The feed size
planned is 105 mm with Axb =40 (Mia =19.1), Wi =12,
and the expected T80 around 3 mm.
The SAG mill size is 38’x22’ operating in a closed cir-
cuit without a pebble crusher.
Determine what the %ball load and speed (rpm)
should be.
Step 1
Firstly, it is necessary to calculate the specific energy for the
required duty, then multiply by the desired throughput to
get the process power. The SAG equation proposed by the
author (Procemin 2020) is used:
W C Mia F
C Wi TS
.
.
F F80
TS TS
1
0 80
80
2 80
0 8
.
.
0 05
0 05
##
##
=-
+-
##
##
--0.8
--0.8
--0.05
--0.05 `P
`TS
j
j
.
,000
,000
W
TS
TS
30 19 5
105
10 12
,000
,000
.TS TS
105
105
0 8 .0 05
##
##
=
-
+-
#
#
##
-0.8
-0.8
--0.8
-0.05
-0.05
--0.05 _3
f p
i
W =6.6 kW/t (net specific energy
W =6.6/0.93 =7.1 kW/t (gross specific energy).
(0.93 because the model was fitted with 93% efficiency)
P T W Throughput Gross Specific Energy
gross ##==
,.1 .05 P t
kWh 2 150 7 1 tph
gross ##=(5% additional
power is needed because there is no pebble crusher)
,048 P 16 kW
gross =
Step 2
Secondly, it is necessary to calculate what the %ball load,
%total load, and speed should be to draw 16,048 kW for
the SAG mill 38'×22'. The recent power model for tum-
bling mills by the author (Procemin 2023 and IMPC 2024)
is used:
tan P kD DJ J Se ..7
gross b c
2 9 0 2 a/3i_J =+-_L ^0.05ARh it
Figure 4. Author model vs industrial data sets for SAG, AG and ball mills
Table 2. Accuracy of the proposed model
%Relative Error SAG&AG Ball All Mills
Mean –0.25 0.02 –0.15
Standard deviation 5.03 4.11 4.72
95% confidence level 9.85 8.06 9.24
PRACTICAL CASE
A customer requires processing 2,150 tph. The feed size
planned is 105 mm with Axb =40 (Mia =19.1), Wi =12,
and the expected T80 around 3 mm.
The SAG mill size is 38’x22’ operating in a closed cir-
cuit without a pebble crusher.
Determine what the %ball load and speed (rpm)
should be.
Step 1
Firstly, it is necessary to calculate the specific energy for the
required duty, then multiply by the desired throughput to
get the process power. The SAG equation proposed by the
author (Procemin 2020) is used:
W C Mia F
C Wi TS
.
.
F F80
TS TS
1
0 80
80
2 80
0 8
.
.
0 05
0 05
##
##
=-
+-
##
##
--0.8
--0.8
--0.05
--0.05 `P
`TS
j
j
.
,000
,000
W
TS
TS
30 19 5
105
10 12
,000
,000
.TS TS
105
105
0 8 .0 05
##
##
=
-
+-
#
#
##
-0.8
-0.8
--0.8
-0.05
-0.05
--0.05 _3
f p
i
W =6.6 kW/t (net specific energy
W =6.6/0.93 =7.1 kW/t (gross specific energy).
(0.93 because the model was fitted with 93% efficiency)
P T W Throughput Gross Specific Energy
gross ##==
,.1 .05 P t
kWh 2 150 7 1 tph
gross ##=(5% additional
power is needed because there is no pebble crusher)
,048 P 16 kW
gross =
Step 2
Secondly, it is necessary to calculate what the %ball load,
%total load, and speed should be to draw 16,048 kW for
the SAG mill 38'×22'. The recent power model for tum-
bling mills by the author (Procemin 2023 and IMPC 2024)
is used:
tan P kD DJ J Se ..7
gross b c
2 9 0 2 a/3i_J =+-_L ^0.05ARh it
Figure 4. Author model vs industrial data sets for SAG, AG and ball mills
Table 2. Accuracy of the proposed model
%Relative Error SAG&AG Ball All Mills
Mean –0.25 0.02 –0.15
Standard deviation 5.03 4.11 4.72
95% confidence level 9.85 8.06 9.24