130 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
employees and how they react to adopting, accepting, and
using new kinds of implemented technology in a business
environment.
Companies need to ask themselves “are we Innovators/
Early Adopters or Laggards” when it comes to using inno-
vative technology on a project. Several factors relate to this,
a company’s appetite for innovation, their ability to manage
risk and their ability to minimize risks. Operators reduce
risks by either costly demonstration plants or limiting the
consequences of risks, i.e., having multiple operations that
offers the ability to absorb the potential negative conse-
quence of the risk (vs the single asset operator). Projects
with high profitability or Internal Rate of Return (IRR) are
seen as staying with the more proven technology or what is
more widely accepted, while the lower return projects are
looking for what they can do to make the project more
feasible and to increase their IRR.
Another way projects are compared is through bench-
marking the success and failures of recently completed
projects and the timeline needed to ramp-up their design
rates. McNulty Curves (Figure 2) have become the standard
for making these comparisons. Figure 1 shows the average
ramp-up profiles for four different project categories with
varying levels of integrating innovative technology. The red
line stands for a project that had a difficult startup but then
gradually recovered after either infusions of capital to make
modifications or the installation of new equipment.
McNulty Curves are used to measure performance and
to forecast expectations based on what risks were taken
by a specific project. Mining companies are in business to
deliver financial returns to investors. They must manage
through the highs and the lows of metal price cycles. In
addition, businesses tend to focus on short term returns,
which drives incremental and/or continuous improvement
in their operations. Let us start by looking at the Primary
Grinding circuits and what changes have occurred and their
associated risks.
PRIMARY GRINDING
Note: The turn of century copper plants e.g., Arthur, Magna,
Ely used multiple lines of roll crushers, followed by primary
and secondary ball mills (this is an interesting note as the roll
mills reappear as HPGR a half century later).
The most common Copper grinding circuits of the
1960–1980 era were Rod/Ball mill combinations running
in parallel or Primary Ball mills e.g., San Manuel (Figure 3),
Morenci, Mission, Chuquicamata, Freeport Indonesia
etc. These plants had small 3.05–5.5 m (10–18 ft) diam-
eter Ball mills in multiple grinding lines. As an example,
Magma San Manuel operation ran (13) grinding lines with
a throughput of 59,875 tpd, (66,000 stph) the mill avail-
ability ranged from 96% to 98%. These mills were fed by a
Primary/Secondary and Tertiary crushing circuits providing
a crushed ore p80 of 12.5 mm (0.5 inch). With the small,
parallel mill lines, when one rod mill was down only ~10%
Source: ReasearchGate.net
Figure 2. McNulty Project Categories
employees and how they react to adopting, accepting, and
using new kinds of implemented technology in a business
environment.
Companies need to ask themselves “are we Innovators/
Early Adopters or Laggards” when it comes to using inno-
vative technology on a project. Several factors relate to this,
a company’s appetite for innovation, their ability to manage
risk and their ability to minimize risks. Operators reduce
risks by either costly demonstration plants or limiting the
consequences of risks, i.e., having multiple operations that
offers the ability to absorb the potential negative conse-
quence of the risk (vs the single asset operator). Projects
with high profitability or Internal Rate of Return (IRR) are
seen as staying with the more proven technology or what is
more widely accepted, while the lower return projects are
looking for what they can do to make the project more
feasible and to increase their IRR.
Another way projects are compared is through bench-
marking the success and failures of recently completed
projects and the timeline needed to ramp-up their design
rates. McNulty Curves (Figure 2) have become the standard
for making these comparisons. Figure 1 shows the average
ramp-up profiles for four different project categories with
varying levels of integrating innovative technology. The red
line stands for a project that had a difficult startup but then
gradually recovered after either infusions of capital to make
modifications or the installation of new equipment.
McNulty Curves are used to measure performance and
to forecast expectations based on what risks were taken
by a specific project. Mining companies are in business to
deliver financial returns to investors. They must manage
through the highs and the lows of metal price cycles. In
addition, businesses tend to focus on short term returns,
which drives incremental and/or continuous improvement
in their operations. Let us start by looking at the Primary
Grinding circuits and what changes have occurred and their
associated risks.
PRIMARY GRINDING
Note: The turn of century copper plants e.g., Arthur, Magna,
Ely used multiple lines of roll crushers, followed by primary
and secondary ball mills (this is an interesting note as the roll
mills reappear as HPGR a half century later).
The most common Copper grinding circuits of the
1960–1980 era were Rod/Ball mill combinations running
in parallel or Primary Ball mills e.g., San Manuel (Figure 3),
Morenci, Mission, Chuquicamata, Freeport Indonesia
etc. These plants had small 3.05–5.5 m (10–18 ft) diam-
eter Ball mills in multiple grinding lines. As an example,
Magma San Manuel operation ran (13) grinding lines with
a throughput of 59,875 tpd, (66,000 stph) the mill avail-
ability ranged from 96% to 98%. These mills were fed by a
Primary/Secondary and Tertiary crushing circuits providing
a crushed ore p80 of 12.5 mm (0.5 inch). With the small,
parallel mill lines, when one rod mill was down only ~10%
Source: ReasearchGate.net
Figure 2. McNulty Project Categories