132 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
These “Silos” will need to be recognized and removed for
Asset Management to be 100% effective. The industry has
been slow to invest in more conditioning monitoring to
predict failure rates. The trend to move towards AI to better
predict root cause failures and how to extend the meantime
intervals between SAG mill outages will become a competi-
tive edge for companies.
FLOTATION CIRCUITS
Flotation cell size has followed the same trends as grind-
ing equipment, but even more dramatically. In the early
60s there were plants with multiple rows of 1.4 m3 (48 ft3)
cells (Figure 6) and in the 70s that grew to multiple rows of
8.5 m3 (300 ft3). In the next 10 years the cell size jumped
4-times to 38 m3 (1,300 ft3) and the next period jumped
10-times to 300 m3 (10,600 ft3) and half the number of
rows.
Again, the strong driver for this change was the smaller
footprint, coupled with the ability to add more retention
time. The 150 m3 (Figure 7) and 300 m3 Tank cells were
reporting retention times of 30–40 minutes for copper
roughing, twice that of the smaller cells in the earlier era.
Another factor in the older plants with the smaller cells
was they had significantly less froth drop-back than the
large Tank cells. Recent published papers have discussed
how to improve froth collection with more launders/
crowders, but this has not fully eliminated the problem.
Source: R Johnson
Figure 5. Downtime costs for a large SABC
Source: Tucson.com
Figure 6. Rougher rows (Magma San Manel)
Source: R Johnson 2021
Figure 7. Rougher rows (KazMinerals Aktogay II)

Previous Page Next Page

Extracted Text (may have errors)

132 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
These “Silos” will need to be recognized and removed for
Asset Management to be 100% effective. The industry has
been slow to invest in more conditioning monitoring to
predict failure rates. The trend to move towards AI to better
predict root cause failures and how to extend the meantime
intervals between SAG mill outages will become a competi-
tive edge for companies.
FLOTATION CIRCUITS
Flotation cell size has followed the same trends as grind-
ing equipment, but even more dramatically. In the early
60s there were plants with multiple rows of 1.4 m3 (48 ft3)
cells (Figure 6) and in the 70s that grew to multiple rows of
8.5 m3 (300 ft3). In the next 10 years the cell size jumped
4-times to 38 m3 (1,300 ft3) and the next period jumped
10-times to 300 m3 (10,600 ft3) and half the number of
rows.
Again, the strong driver for this change was the smaller
footprint, coupled with the ability to add more retention
time. The 150 m3 (Figure 7) and 300 m3 Tank cells were
reporting retention times of 30–40 minutes for copper
roughing, twice that of the smaller cells in the earlier era.
Another factor in the older plants with the smaller cells
was they had significantly less froth drop-back than the
large Tank cells. Recent published papers have discussed
how to improve froth collection with more launders/
crowders, but this has not fully eliminated the problem.
Source: R Johnson
Figure 5. Downtime costs for a large SABC
Source: Tucson.com
Figure 6. Rougher rows (Magma San Manel)
Source: R Johnson 2021
Figure 7. Rougher rows (KazMinerals Aktogay II)

Help

Destination page number Search scope Search Text

loading

XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 131
of the total throughput was affected. Crushed ore feed bins
ahead of the mills provided 12 to 24-hour surge capacity
as a buffer between the crushers and the mills to mitigate
feed upsets. High capital cost was the principal downsize of
these smaller mills with their large building footprint.
In the late 70s and early 80s the Autogenous (AG)
and Semi-Autogenous (SAG) mills were being introduced
to copper processing, first with single-pinion drives which
later switching to dual-pinion drives. The size of these early
AG mills ranged from 5.5 m (18ft) diameter installed in
Australia to 9.8 m (32 ft) installed in Canada. The con-
nected power ranging from single pinons of 932 kW
(1,250 hp) at Kanmantoo to dual pinion and 8948 kW
(12,000 hp) at Island Copper. After start-up, operators of
single AG mill circuits increased throughput by installing
Ball mills and then also adding pebble crushing, these con-
figurations were referred to as ABC circuits. Cyprus Bagdad
would be one of the first innovators with the installation of
an ABC circuit. Utah’s Island Copper operation was also an
early adaptor starling with AG mills only, then later adding
Ball mills and then converting to Sag mills or to SAB cir-
cuits. Most common today is the addition of pebble crush-
ers to the SAB circuits or now referred to as SABC circuits
(Figure 4)
Dual pinons had become more common with the larger
mills and now Gearless Motor Drives (GMD) were being
introduced. The SAG mill size would then increase over the
next period from 11 m (36 ft) to 12.2 m (40 ft) diameter.
The connected power ranging from 9 MW (12,000 hp) to
28 MW (37,550 hp). Dual pinion drives were limited to ~
9–12 MW and the GMDs 12 MW. The feed size to these
large SABC circuits was 150–200 mm (6–8 inch). The
main design variables were ore hardness and the potential
for the accumulation of critical size material in the SAG
mills. The solution was the introduction of pebble ports
to the discharge grates to relieve the AG/SAG mills. This
change led to the addition of cone crushers to crush the
pebbles, resulting to an increase the p80 transfer size of the
Ball mills.
The recent introduction of High-Pressure Grinding
Rolls (HPGR) and their higher efficiency, particularly for
harder ores has challenged the SABC circuits, however,
it still is the standard for copper process at the present.
One interesting twist has been the use of the HPGR in
the pebble crushing circuits. Goldcorp’s Penasquito Mine
and KazMinerals’ mines at Bozshakol/Aktogay have 2-stage
pebble crushing. Throughput increases have been reported
as high as 30% with the addition of the HPGR on their
hardest ore. Another group of early innovators in pebble
crushing for Gold circuits were at the Lone Tree and Jerrin
Canyon operations.
With fewer mills and more throughput per mill cir-
cuit becoming the norm, availability becomes the primary
focus. When the SAG mill is down for a liner change can
mean 100% loss of tonnage versus 10% with the smaller
multiply lines (Figure 5). Asset Management programs
have become more of a “Must Have” versus a “Nice to
Have” feature. Maintenance and Operations are shifting
towards a “Turnaround” mentality versus partial mainte-
nance based on processed tonnage/operating hours. Asset
Management is assimilating a plantwide data system that
is inclusive of all phases of Operations. The one thing that
threatens this integration is the existing “Silos” between the
various divisions, when it comes to sharing information.
Source: Tucson.com
Figure 3. Copper Processing (Magma San Manuel)
Source: R Johnson at KazMinerals Aktogay II 2021
Figure 4. SABC Circuit Copper Mine

Previous Page Next Page

Extracted Text (may have errors)

XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 131
of the total throughput was affected. Crushed ore feed bins
ahead of the mills provided 12 to 24-hour surge capacity
as a buffer between the crushers and the mills to mitigate
feed upsets. High capital cost was the principal downsize of
these smaller mills with their large building footprint.
In the late 70s and early 80s the Autogenous (AG)
and Semi-Autogenous (SAG) mills were being introduced
to copper processing, first with single-pinion drives which
later switching to dual-pinion drives. The size of these early
AG mills ranged from 5.5 m (18ft) diameter installed in
Australia to 9.8 m (32 ft) installed in Canada. The con-
nected power ranging from single pinons of 932 kW
(1,250 hp) at Kanmantoo to dual pinion and 8948 kW
(12,000 hp) at Island Copper. After start-up, operators of
single AG mill circuits increased throughput by installing
Ball mills and then also adding pebble crushing, these con-
figurations were referred to as ABC circuits. Cyprus Bagdad
would be one of the first innovators with the installation of
an ABC circuit. Utah’s Island Copper operation was also an
early adaptor starling with AG mills only, then later adding
Ball mills and then converting to Sag mills or to SAB cir-
cuits. Most common today is the addition of pebble crush-
ers to the SAB circuits or now referred to as SABC circuits
(Figure 4)
Dual pinons had become more common with the larger
mills and now Gearless Motor Drives (GMD) were being
introduced. The SAG mill size would then increase over the
next period from 11 m (36 ft) to 12.2 m (40 ft) diameter.
The connected power ranging from 9 MW (12,000 hp) to
28 MW (37,550 hp). Dual pinion drives were limited to ~
9–12 MW and the GMDs 12 MW. The feed size to these
large SABC circuits was 150–200 mm (6–8 inch). The
main design variables were ore hardness and the potential
for the accumulation of critical size material in the SAG
mills. The solution was the introduction of pebble ports
to the discharge grates to relieve the AG/SAG mills. This
change led to the addition of cone crushers to crush the
pebbles, resulting to an increase the p80 transfer size of the
Ball mills.
The recent introduction of High-Pressure Grinding
Rolls (HPGR) and their higher efficiency, particularly for
harder ores has challenged the SABC circuits, however,
it still is the standard for copper process at the present.
One interesting twist has been the use of the HPGR in
the pebble crushing circuits. Goldcorp’s Penasquito Mine
and KazMinerals’ mines at Bozshakol/Aktogay have 2-stage
pebble crushing. Throughput increases have been reported
as high as 30% with the addition of the HPGR on their
hardest ore. Another group of early innovators in pebble
crushing for Gold circuits were at the Lone Tree and Jerrin
Canyon operations.
With fewer mills and more throughput per mill cir-
cuit becoming the norm, availability becomes the primary
focus. When the SAG mill is down for a liner change can
mean 100% loss of tonnage versus 10% with the smaller
multiply lines (Figure 5). Asset Management programs
have become more of a “Must Have” versus a “Nice to
Have” feature. Maintenance and Operations are shifting
towards a “Turnaround” mentality versus partial mainte-
nance based on processed tonnage/operating hours. Asset
Management is assimilating a plantwide data system that
is inclusive of all phases of Operations. The one thing that
threatens this integration is the existing “Silos” between the
various divisions, when it comes to sharing information.
Source: Tucson.com
Figure 3. Copper Processing (Magma San Manuel)
Source: R Johnson at KazMinerals Aktogay II 2021
Figure 4. SABC Circuit Copper Mine

XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 133
Froth cameras have also improved/stabilized their perfor-
mance, but their addition has not reduced the number of
installed cells. Retention times vary naturally and are based
on the kinetics of the ore body. Another factor that has
increased is the concentrate mass pulls, small cells typically
had mass pulls that were less than 10%, the Tank cells this
number is as high as 20%. These differences were initially
defined as coming from orebodies with more pyrite and
clay content, but an expressed concern now is being told
more in terms of an efficient factor for both recovery and
upgrading (ratio of concentration).
The industry has always debated what was better,
“forced-air” float machines or “self-aspirating.” Those oper-
ators that felt they wanted more control over their flotation
circuits, were proponents of the forced-air cells. Those that
wanted to remove operator variability like the self-aspirat-
ing cells better. This author had an opportunity to install
both types in the same plant and then measure their perfor-
mance on the same ore. In that operation the self-aspirating
cells received the best overall recovery. But years later in
another plant a design opportunity allowed for the instal-
lation of both types of cells in the same float bank. In this
case, the forced-air cells won but not on performance, but
for maintenance reasons.
Initially, plant designs used these large Tank cells,
Jameson (Figure 8), and OK’s Skim-Air (Figure 9) cells as
Pre-Roughers or Scalpers, to recover the fast-floating mate-
rial and then followed with the smaller cells to achieve their
targeted recovery.
The concept of Pre-Roughers led to the development of
a whole series of new cells e.g., Eriez’s Stackcell (Figure 10),
Woodgrove’s Stage Flotation Reactor (SFR), Direct
Stage Reactor (DFR) (Figure 11), etc.
In these new cells, the metal recoveries are achieved
in seconds as compared to traditional cells where it takes
minutes to obtain the similar recoveries. Operators are now
debating fundamental questions on what recovery stage is
most important, the mineral collection zone or the mixing
Source: en.wikipedia.org
Figure 8. Jameson cell

Previous Page Next Page

Extracted Text (may have errors)

XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 133
Froth cameras have also improved/stabilized their perfor-
mance, but their addition has not reduced the number of
installed cells. Retention times vary naturally and are based
on the kinetics of the ore body. Another factor that has
increased is the concentrate mass pulls, small cells typically
had mass pulls that were less than 10%, the Tank cells this
number is as high as 20%. These differences were initially
defined as coming from orebodies with more pyrite and
clay content, but an expressed concern now is being told
more in terms of an efficient factor for both recovery and
upgrading (ratio of concentration).
The industry has always debated what was better,
“forced-air” float machines or “self-aspirating.” Those oper-
ators that felt they wanted more control over their flotation
circuits, were proponents of the forced-air cells. Those that
wanted to remove operator variability like the self-aspirat-
ing cells better. This author had an opportunity to install
both types in the same plant and then measure their perfor-
mance on the same ore. In that operation the self-aspirating
cells received the best overall recovery. But years later in
another plant a design opportunity allowed for the instal-
lation of both types of cells in the same float bank. In this
case, the forced-air cells won but not on performance, but
for maintenance reasons.
Initially, plant designs used these large Tank cells,
Jameson (Figure 8), and OK’s Skim-Air (Figure 9) cells as
Pre-Roughers or Scalpers, to recover the fast-floating mate-
rial and then followed with the smaller cells to achieve their
targeted recovery.
The concept of Pre-Roughers led to the development of
a whole series of new cells e.g., Eriez’s Stackcell (Figure 10),
Woodgrove’s Stage Flotation Reactor (SFR), Direct
Stage Reactor (DFR) (Figure 11), etc.
In these new cells, the metal recoveries are achieved
in seconds as compared to traditional cells where it takes
minutes to obtain the similar recoveries. Operators are now
debating fundamental questions on what recovery stage is
most important, the mineral collection zone or the mixing
Source: en.wikipedia.org
Figure 8. Jameson cell