2
brochantite, chrysocolla and could contain native copper,
cuprite and tenorite.
Hydrothermal alteration at Mantoverde is very similar
across all the Cu-Au orebodies and characterized by vari-
ably intense potassic (k-feldspar) alteration, chloritization,
sericitization, silicification, and/or carbonatization.
Cobalt mineralization occurs primarily as solid solu-
tion in pyrite, with cobalt replacement of iron in the pyrite
crystal lattice. Cobalt tenor various throughout the deposit,
with higher cobalt grades to the south, associated with the
magnetite zone. Additionally, some cobalt is present in the
oxide and mixed materials, primarily a result of oxidative
weathering of the original host pyrite minerals. Figure 1
shows an example of cobalt concentration in a pyrite grain
from Mantoverde.
Heap Leach and Solvent Extraction
Mantoverde’s dynamic leach pad (DLP) is an on/off pad
measuring approximately 700 m × 900 m and capable
of treating approximately 11 million tonnes per year of
crushed ore. The South Dump II (SDII) leach pad is a run-
of-mine leach system with the capability of expansion as
needed.
Ore is delivered to one of the two leaching operations
based on copper and carbonate grades. Typically, higher
copper and lower carbonate grade ores are sent to the
dynamic leach pad and the balance to South Dump II.
DLP ore is delivered from the pit to a primary crusher
and then conveyed to a coarse ore stockpile. The ore is then
fed by conveyor to a vibrating screen, with the oversize
reporting to a secondary cone crusher. The crusher product
is then conveyed to five surge bins, which feed five tertiary
screens. The screen oversize feeds the five tertiary crushers.
The final crushed ore product is stored in two bins that feed
the two parallel agglomeration drums. Agglomerated ore is
transported by a system of overland conveyors, grasshop-
pers and tripper conveyors to a stacker which places the
ore on the dynamic leach pads in a 7 m high lift. Sulfuric
acid and raffinate are added at the agglomeration drum.
Leaching is performed in 120-day cycles, after which the
spent leach residue is unloaded and placed in a dedicated
leached waste dump via bucket wheel and overland con-
veyor. The unloading is augmented by shovel and truck as
required.
Leaching is accomplished by irrigating the ore with a
dilute sulfuric acid solution using either intermediate leach
solution (ILS) or raffinate. The use of intermediate leach
solutions allows for the pregnant leach solution grade to be
maximized. Solution leaving the DLP flows into a PLS or
ILS pond based on the copper grade. The PLS pond feeds
the SX circuit, and the ILS pond is used for irrigation.
The dynamic heap leach pad operation is comple-
mented by a run-of-mine dump leaching process. Material
for dump leaching is deposited directly on the pad via
truck dumping without crushing. Lift heights of 20 m are
employed. The ore is initially exposed to a high acid cure
followed by a leach cycle consisting of intermediate leach
solution (ILS) and raffinate. Like the DLP, the SDII uses
an ILS solution to maximize the PLS grade. The PLS from
SDII PLS pond reports to a common PLS pond close to the
solvent extraction (SX) plant.
The common PLS solution flows to the solvent extrac-
tion circuit where it is contacted with an organic reagent
and diluent to adsorb the copper. Mantoverde utilizes a
split SX circuit with two parallel lines: one with two mix-
ers/settlers in series (E1/E2) and one with only one mixer/
Figure 1. Photomicrograph (left) and scanning electron microprobe image (right) showing Co concentration in a cobaltiferous
pyrite grain, hydrothermal brecchia, Mantoverde (Valencia Geoservices, Tucson, AZ)
brochantite, chrysocolla and could contain native copper,
cuprite and tenorite.
Hydrothermal alteration at Mantoverde is very similar
across all the Cu-Au orebodies and characterized by vari-
ably intense potassic (k-feldspar) alteration, chloritization,
sericitization, silicification, and/or carbonatization.
Cobalt mineralization occurs primarily as solid solu-
tion in pyrite, with cobalt replacement of iron in the pyrite
crystal lattice. Cobalt tenor various throughout the deposit,
with higher cobalt grades to the south, associated with the
magnetite zone. Additionally, some cobalt is present in the
oxide and mixed materials, primarily a result of oxidative
weathering of the original host pyrite minerals. Figure 1
shows an example of cobalt concentration in a pyrite grain
from Mantoverde.
Heap Leach and Solvent Extraction
Mantoverde’s dynamic leach pad (DLP) is an on/off pad
measuring approximately 700 m × 900 m and capable
of treating approximately 11 million tonnes per year of
crushed ore. The South Dump II (SDII) leach pad is a run-
of-mine leach system with the capability of expansion as
needed.
Ore is delivered to one of the two leaching operations
based on copper and carbonate grades. Typically, higher
copper and lower carbonate grade ores are sent to the
dynamic leach pad and the balance to South Dump II.
DLP ore is delivered from the pit to a primary crusher
and then conveyed to a coarse ore stockpile. The ore is then
fed by conveyor to a vibrating screen, with the oversize
reporting to a secondary cone crusher. The crusher product
is then conveyed to five surge bins, which feed five tertiary
screens. The screen oversize feeds the five tertiary crushers.
The final crushed ore product is stored in two bins that feed
the two parallel agglomeration drums. Agglomerated ore is
transported by a system of overland conveyors, grasshop-
pers and tripper conveyors to a stacker which places the
ore on the dynamic leach pads in a 7 m high lift. Sulfuric
acid and raffinate are added at the agglomeration drum.
Leaching is performed in 120-day cycles, after which the
spent leach residue is unloaded and placed in a dedicated
leached waste dump via bucket wheel and overland con-
veyor. The unloading is augmented by shovel and truck as
required.
Leaching is accomplished by irrigating the ore with a
dilute sulfuric acid solution using either intermediate leach
solution (ILS) or raffinate. The use of intermediate leach
solutions allows for the pregnant leach solution grade to be
maximized. Solution leaving the DLP flows into a PLS or
ILS pond based on the copper grade. The PLS pond feeds
the SX circuit, and the ILS pond is used for irrigation.
The dynamic heap leach pad operation is comple-
mented by a run-of-mine dump leaching process. Material
for dump leaching is deposited directly on the pad via
truck dumping without crushing. Lift heights of 20 m are
employed. The ore is initially exposed to a high acid cure
followed by a leach cycle consisting of intermediate leach
solution (ILS) and raffinate. Like the DLP, the SDII uses
an ILS solution to maximize the PLS grade. The PLS from
SDII PLS pond reports to a common PLS pond close to the
solvent extraction (SX) plant.
The common PLS solution flows to the solvent extrac-
tion circuit where it is contacted with an organic reagent
and diluent to adsorb the copper. Mantoverde utilizes a
split SX circuit with two parallel lines: one with two mix-
ers/settlers in series (E1/E2) and one with only one mixer/
Figure 1. Photomicrograph (left) and scanning electron microprobe image (right) showing Co concentration in a cobaltiferous
pyrite grain, hydrothermal brecchia, Mantoverde (Valencia Geoservices, Tucson, AZ)