124 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
annual copper production – Visual Capitalist, (2023))
operation in Peru is considered, the combined ore feed to
C1 and C2 concentrators is approximately 140Mtpa (or
412,000tpd) .The feed tonnage is treated through the use
of HPGR, followed by ball mills, as follows:
• C1 -one primary gyratory crusher, four secondary
cone crushers in closed circuit with four dry vibrating
screens, and four HPGR tertiary crushers in closed
circuit with eight wet vibrating screens. The grinding
circuit consists of four parallel lines, with each grind-
ing line comprising of one ball mill, one cyclone feed
pump, and one cyclone cluster. The grind size gener-
ated is approximately 180microns.
• C2 -two primary gyratory crushers, eight second-
ary cone crushers in closed circuit with eight dry
vibrating screens, and eight HPGR tertiary crushers
in closed circuit with twelve wet vibrating screens.
The grinding circuit consists of six parallel lines, with
each grinding line comprising of one ball mill, one
cyclone feed pump, and one cyclone cluster. The
grind size generated is approximately 160microns.
In the case of the Iron Bridge magnetite operation, the
plant feed is 67dmtpa, with all feed through two FLS
63–130 primary gyratory crushers, followed by six Sandvik
CH890 cone crushers in open circuit with four Weir
Enduron HPGR (2.4 x 2.25m) in a tertiary crushing duty
at 27,200dt/hr. Following crushing, approximately 20%
is rejected to waste via dry magnetic separation, with the
remaining ore reporting to eight Weir HPGR (2.2 x 2m)
units deployed in a primary grinding duty at 19,000dt/h.
The differentiator for Iron Bridge is the absence of ball
mills, instead using wet stirred mills after the dry HPGR
treatment. HIG mills from Outotec are deployed in sec-
ondary and tertiary grinding duties, as follows:
• Secondary Milling – Eight 5MW mills, with a design
feed rate of 3,433 m3/h of upstream cyclone under-
flow product to the milling plant. Mill feed F80:
85–115 micron, with mill product P80: 35 micron.
Circuit configuration: open circuit
• Tertiary Milling – Two 5MW mills, with a design
feed rate of 933 m3/h of upstream screen oversize
product. Mill feed F80: 66 micron, with mill prod-
uct P80: 26–30 micron. Circuit configuration: open
circuit.
The design of the Iron Bridge circuit is claimed to reduce
both energy consumption and wet tailings waste by 30%
compared to a traditional magnetite plant.
Obviously with multiple HPGR units in parallel, the
materials handling and associated equipment requirements
increase. The degree of complexity is directly related to the
number of units required to meet the feed tonnage. One
obvious way to reduce this requirement is to reduce the
plant feed rate, but maintain the metal content, i.e., the
aim of coarse preconcentration.
If the Iron Bridge example is considered, it is the use
of dry magnetic separation, after tertiary HPGR, to reject
20% of the feed, which allows the subsequent process
design to be reduced in size and complexity. The use of
magnetic separation for waste rejection is, however, not
widely applicable.
Although subject to various delays due to the nature
of the nickel market, another project in development that
is potentially introducing a range of innovations, is West
Musgrave in Western Australia. West Musgrave is a nickel-
copper project, with the main innovative features being:
• Use of Loesche Vertical Roller Mill (VRM) for dry
grinding of ore to 165 microns
• Design of the bulk separation flotation circuit to suit
treatment of the 165 micron feed
• A focus on renewable power generation, via both
wind and solar power generation and changes to
operational run hours to better suit the source of
power.
In the wider set of commodities, the standard pieces of
equipment noted above, i.e., crushers, HPGR, stirred mills
are all in the mix for future circuit design, with their use
in various circuit configurations being highly effective in
terms of energy (Morrell, 2022).
The overall impact of replacing an SABC circuit, with
various combinations of HPGR, stirred mils and Coarse
Particle Flotation has been examined by Weir, SLR, (2023).
The calculated values for a typical SABC circuit and the
possible improvements are shown in Table 1.
It is important to note that the energy emission factor
used in Table 1 was taken to be the value for grid electricity
in Chile in 2020 and reported by the IEA, (2022) and the
emission factor for the grinding media is from publications
cited by SLR.
In terms of evaluations from others, Morrell, (2023),
also examined potential savings from replacement of AG/
SAG with HPGR and concluded that a gain of approxi-
mately 20% is possible and if the circuit is changed further
to replace AG/SAG and ball mills with HPGR, then the
gain is approximately 40%. In these terms there appears to
be general agreement on the types of improvement that are
possible.
annual copper production – Visual Capitalist, (2023))
operation in Peru is considered, the combined ore feed to
C1 and C2 concentrators is approximately 140Mtpa (or
412,000tpd) .The feed tonnage is treated through the use
of HPGR, followed by ball mills, as follows:
• C1 -one primary gyratory crusher, four secondary
cone crushers in closed circuit with four dry vibrating
screens, and four HPGR tertiary crushers in closed
circuit with eight wet vibrating screens. The grinding
circuit consists of four parallel lines, with each grind-
ing line comprising of one ball mill, one cyclone feed
pump, and one cyclone cluster. The grind size gener-
ated is approximately 180microns.
• C2 -two primary gyratory crushers, eight second-
ary cone crushers in closed circuit with eight dry
vibrating screens, and eight HPGR tertiary crushers
in closed circuit with twelve wet vibrating screens.
The grinding circuit consists of six parallel lines, with
each grinding line comprising of one ball mill, one
cyclone feed pump, and one cyclone cluster. The
grind size generated is approximately 160microns.
In the case of the Iron Bridge magnetite operation, the
plant feed is 67dmtpa, with all feed through two FLS
63–130 primary gyratory crushers, followed by six Sandvik
CH890 cone crushers in open circuit with four Weir
Enduron HPGR (2.4 x 2.25m) in a tertiary crushing duty
at 27,200dt/hr. Following crushing, approximately 20%
is rejected to waste via dry magnetic separation, with the
remaining ore reporting to eight Weir HPGR (2.2 x 2m)
units deployed in a primary grinding duty at 19,000dt/h.
The differentiator for Iron Bridge is the absence of ball
mills, instead using wet stirred mills after the dry HPGR
treatment. HIG mills from Outotec are deployed in sec-
ondary and tertiary grinding duties, as follows:
• Secondary Milling – Eight 5MW mills, with a design
feed rate of 3,433 m3/h of upstream cyclone under-
flow product to the milling plant. Mill feed F80:
85–115 micron, with mill product P80: 35 micron.
Circuit configuration: open circuit
• Tertiary Milling – Two 5MW mills, with a design
feed rate of 933 m3/h of upstream screen oversize
product. Mill feed F80: 66 micron, with mill prod-
uct P80: 26–30 micron. Circuit configuration: open
circuit.
The design of the Iron Bridge circuit is claimed to reduce
both energy consumption and wet tailings waste by 30%
compared to a traditional magnetite plant.
Obviously with multiple HPGR units in parallel, the
materials handling and associated equipment requirements
increase. The degree of complexity is directly related to the
number of units required to meet the feed tonnage. One
obvious way to reduce this requirement is to reduce the
plant feed rate, but maintain the metal content, i.e., the
aim of coarse preconcentration.
If the Iron Bridge example is considered, it is the use
of dry magnetic separation, after tertiary HPGR, to reject
20% of the feed, which allows the subsequent process
design to be reduced in size and complexity. The use of
magnetic separation for waste rejection is, however, not
widely applicable.
Although subject to various delays due to the nature
of the nickel market, another project in development that
is potentially introducing a range of innovations, is West
Musgrave in Western Australia. West Musgrave is a nickel-
copper project, with the main innovative features being:
• Use of Loesche Vertical Roller Mill (VRM) for dry
grinding of ore to 165 microns
• Design of the bulk separation flotation circuit to suit
treatment of the 165 micron feed
• A focus on renewable power generation, via both
wind and solar power generation and changes to
operational run hours to better suit the source of
power.
In the wider set of commodities, the standard pieces of
equipment noted above, i.e., crushers, HPGR, stirred mills
are all in the mix for future circuit design, with their use
in various circuit configurations being highly effective in
terms of energy (Morrell, 2022).
The overall impact of replacing an SABC circuit, with
various combinations of HPGR, stirred mils and Coarse
Particle Flotation has been examined by Weir, SLR, (2023).
The calculated values for a typical SABC circuit and the
possible improvements are shown in Table 1.
It is important to note that the energy emission factor
used in Table 1 was taken to be the value for grid electricity
in Chile in 2020 and reported by the IEA, (2022) and the
emission factor for the grinding media is from publications
cited by SLR.
In terms of evaluations from others, Morrell, (2023),
also examined potential savings from replacement of AG/
SAG with HPGR and concluded that a gain of approxi-
mately 20% is possible and if the circuit is changed further
to replace AG/SAG and ball mills with HPGR, then the
gain is approximately 40%. In these terms there appears to
be general agreement on the types of improvement that are
possible.