1
25-052
Iron Concentrator Design for the Santo Domingo Project
Fernanda Solís
Capstone Copper, Santiago, Chile
Peter Amelunxen
Capstone Copper, Vancouver, Canada
Brandon Akerstrom
Capstone Copper, Gilbert, United States of America
Jayson Ripke
McCarl´s Technical Services, United States of
America
ABSTRACT
It is commonly known in the industry that one of the
key challenges for a greenfield project, such as Capstone
Copper’s Santo Domingo project, is the obtention of sam-
ples for metallurgical testing and subsequent plant design.
To face this challenge, the Santo Domingo project com-
pleted 169,692 meters of drilling. The material collected has
been used for a variety of analysis including the economic
recovery of iron, which contributes significant economic
value to the Santo Domingo business case. Composite
and variability samples, covering the main geological units
considered in the life of mine (LOM) plan, were selected
for bench and pilot scale testwork. Davis Tube Tests, small
scale Low Intensity Magnetic Separation (LIMS) tests and
a pilot utilizing a 48 in (1.2 m), diameter magnetic sepa-
ration drum were completed. The testwork demonstrated
that the Santo Domingo ore could achieve iron concentrate
grades of 65% Fe -suitable for blast furnace, and 67% Fe
-suitable for Direct Reduction, primarily by concentration
of magnetite. The outcomes of this work have informed the
iron concentrator plant design and scale up.
BACKGROUND
Santo Domingo is a copper-gold-iron-cobalt project (IOCG
deposit) fully owned by Capstone Copper, a premier cop-
per producer with operations in Chile, United States and
Mexico. Santo Domingo is a permitted project includ-
ing an environmental qualification resolution (or “RCA”
as per the Spanish acronym of Resolución de Calificación
Ambiental), located in the northern Atacama region of
Chile, at an elevation of approximately 1,200 meters above
sea level and consists mainly of two assets, Santo Domingo
and Iris Norte.
Geology of the deposits includes a series of volcani-
clastics and marine-sedimentary rocks with mineralization
consisting mainly of iron-oxide – where the dominant min-
eralization is magnetite and hematite -and sulphide-rich
mantos and breccias within volcano sedimentary rocks with
chalcopyrite as the main copper mineral. Exploration activ-
ities carried out in the property since early 2000´s include
169,692 meters of drilling, establishing 547 Mt measured
plus indicated resources and 436.1 Mt of proven and prob-
able reserves (NI 43-101 Technical Report, 2024). The pro-
posed mining method is open pit with a current mine life
of over 19 years.
The Santo Domingo concentration plant is designed
to recover copper-gold and cobalt-bearing pyrite by sulfide
flotation.
The design also considers feeding the rougher flota-
tion tailings, containing significant magnetite, to an iron
concentration plant. This proposed plant consists of low
intensity magnetic separators (rougher and cleaner) as the
primary unit operations for magnetite concentration, in
conjunction with regrind and hydroseparation as interme-
diate stages. Desalinated water is currently considered as
make-up water for the Santo Domingo concentrator plant.
The circuit designed has been tested using composite and
variability samples and has demonstrated suitability to pro-
duce iron concentrate grades of 65% Fe suitable for blast
furnace and iron concentrate grades of 67% Fe or higher,
suitable for Direct Reduction. Iron concentrate grades of
62% Fe to 65% Fe are considered suitable for iron agglom-
eration processes, such as pelletizing, while lower iron
25-052
Iron Concentrator Design for the Santo Domingo Project
Fernanda Solís
Capstone Copper, Santiago, Chile
Peter Amelunxen
Capstone Copper, Vancouver, Canada
Brandon Akerstrom
Capstone Copper, Gilbert, United States of America
Jayson Ripke
McCarl´s Technical Services, United States of
America
ABSTRACT
It is commonly known in the industry that one of the
key challenges for a greenfield project, such as Capstone
Copper’s Santo Domingo project, is the obtention of sam-
ples for metallurgical testing and subsequent plant design.
To face this challenge, the Santo Domingo project com-
pleted 169,692 meters of drilling. The material collected has
been used for a variety of analysis including the economic
recovery of iron, which contributes significant economic
value to the Santo Domingo business case. Composite
and variability samples, covering the main geological units
considered in the life of mine (LOM) plan, were selected
for bench and pilot scale testwork. Davis Tube Tests, small
scale Low Intensity Magnetic Separation (LIMS) tests and
a pilot utilizing a 48 in (1.2 m), diameter magnetic sepa-
ration drum were completed. The testwork demonstrated
that the Santo Domingo ore could achieve iron concentrate
grades of 65% Fe -suitable for blast furnace, and 67% Fe
-suitable for Direct Reduction, primarily by concentration
of magnetite. The outcomes of this work have informed the
iron concentrator plant design and scale up.
BACKGROUND
Santo Domingo is a copper-gold-iron-cobalt project (IOCG
deposit) fully owned by Capstone Copper, a premier cop-
per producer with operations in Chile, United States and
Mexico. Santo Domingo is a permitted project includ-
ing an environmental qualification resolution (or “RCA”
as per the Spanish acronym of Resolución de Calificación
Ambiental), located in the northern Atacama region of
Chile, at an elevation of approximately 1,200 meters above
sea level and consists mainly of two assets, Santo Domingo
and Iris Norte.
Geology of the deposits includes a series of volcani-
clastics and marine-sedimentary rocks with mineralization
consisting mainly of iron-oxide – where the dominant min-
eralization is magnetite and hematite -and sulphide-rich
mantos and breccias within volcano sedimentary rocks with
chalcopyrite as the main copper mineral. Exploration activ-
ities carried out in the property since early 2000´s include
169,692 meters of drilling, establishing 547 Mt measured
plus indicated resources and 436.1 Mt of proven and prob-
able reserves (NI 43-101 Technical Report, 2024). The pro-
posed mining method is open pit with a current mine life
of over 19 years.
The Santo Domingo concentration plant is designed
to recover copper-gold and cobalt-bearing pyrite by sulfide
flotation.
The design also considers feeding the rougher flota-
tion tailings, containing significant magnetite, to an iron
concentration plant. This proposed plant consists of low
intensity magnetic separators (rougher and cleaner) as the
primary unit operations for magnetite concentration, in
conjunction with regrind and hydroseparation as interme-
diate stages. Desalinated water is currently considered as
make-up water for the Santo Domingo concentrator plant.
The circuit designed has been tested using composite and
variability samples and has demonstrated suitability to pro-
duce iron concentrate grades of 65% Fe suitable for blast
furnace and iron concentrate grades of 67% Fe or higher,
suitable for Direct Reduction. Iron concentrate grades of
62% Fe to 65% Fe are considered suitable for iron agglom-
eration processes, such as pelletizing, while lower iron