The Santo Domingo Project is a fully permitted open pit copper-iron-gold mine located in the Atacama region of Chile.
The mine is 100% owned by Capstone Copper, a Canada-based copper producer. It is operated by Minera Santo Domingo Sociedad Contractual Minera (MSD), a Chilean holding company.
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The project consists of three large deposits- Santo Domingo (composed of Santo Domingo Sur and Iris), Iris Norte, and Estrellita.
In July 2024, Capstone Copper announced the results of an updated feasibility study (FS) for Santo Domingo Project.
The study expects 19 years of mine life and a mineral reserve of 436.1 million tonnes (Mt). Initial capital cost was estimated to be $2.3bn.
According to the company, the integration of Mantoverde, another Capstone mine in proximity, and Santo Domingo, may deliver more than 200,000 tonnes per year of copper.
After the release of the updated FS, Capstone Copper will advance with detailed engineering and project financing. Commercial operations at Santo Domingo may commence in 2028.
Santo Domingo Location
The project is located near the town of Diego de Almagro in Atcama.
The mine lies approximately 35km northeast of the Mantoverde Mine and 130km north-northeast of the city of Copiapó at an elevation of 1,000-1,280 metres above sea level (masl).
Santo Domingo can be accessed via the paved Route 5 North, a Pan-American Highway, and a series of well-maintained gravel roads.
Ownership and Development History
During the early 19th century, the artisanal mining activities started in the Santo Domingo property area, targeting iron and gold.
Modern exploration commenced in 2002. Far West Mining carried out exploration work until 2011. A preliminary assessment was also carried out in 2008.
Capstone Mining (70%) and Korean Resources (KORES) (30%) acquired Far West in June 2011. A pre-feasibility study of the Santo Domingo Sur, Iris, and Iris Norte deposits was completed following the acquisition.
An FS was completed by Capstone in June 2014 on the property, followed by an Environmental Impact Assessment (EIA) in July 2015.
The FS was updated in January 2019. This was followed by a Preliminary Economic Assessment (PEA) on an alternative development option of the project in February 2020.
Capstone acquired 100% of the project by purchasing 30% interest of KORES in April 2021. In March 2022, Capstone and Mantos Copper (Bermuda) merged to form Capstone Copper.
Geology and Mineralisation
Located within the Cretaceous Iron Belt (CIB), the Santo Domingo Project is a part of the iron oxide–copper–gold (IOCG) type deposits that extend approximately 630km by 40km in the coastal range of Chile.
The property is situated on the east side of the Atacama Fault Complex (AFC). The complex consists of several clusters of north-south structural breaks in an approximately 30km wide belt.
The main rocks in the Santo Domingo area are volcanic rocks, volcaniclastic rocks, and a marine-sedimentary sequence related to the Chañarcillo group.
The hydrothermal alteration is characterised by sodic (-calcic), potassic, carbonate and calc-silicate skarn.
The mineralisation in the Santo Domingo deposit comprises stratiform iron-oxide and sulphide-rich mantos and breccias within volcano sedimentary rocks; structurally controlled iron-oxide and sulphide mineralisation, northwest trending iron oxide-copper bearing veins; and minor copper oxides.
Santo Domingo Sur deposit features a 150m to 500m thick copper-bearing, specular hematite–magnetite manto sequence, while the Iris deposit consists of copper-bearing iron mantos and breccias extending 1,900m.
Mineralisation at Iris Norte is similar to that of Iris with a part of by volcaniclastic and andesitic flows.
The Estrellita satellite deposit has a tubular body of copper mineralisation hosted by lesser mantos and specular hematite-rich breccias.
Santo Domingo Project Reserves
According to the updated FS, total Santo Domingo Mineral Reserves is estimated at 436 million tonnes (Mt) at a copper grade of 0.33%, iron ore grade of 26.5%, and a gold grade of 0.05 grams per tonne.
This is 11% more than that of the 2020 Feasibility Study estimate.
Proven mineral reserves are 130.9Mt containing 675kt of copper at a grading of 0.52%, 12.6Mt of magnetite concentrate at a grading of 27.2% iron, and 291koz of gold at a grading of 0.07g/t.
The probable mineral reserves of the Santo Domingo Project stand at 305.1Mt containing 761kt of copper at a grading of 0.25%, 55.8Mt of magnetite concentrate at a grading of 26.2% iron, and 346koz of gold at a grading of 0.04g/t.
It has total Measured and Indicated (M&I) Mineral Resources of 547 million tonnes at a copper grade of 0.31% and a gold grade of 0.04 grams per tonne, including 506 million tonnes with an iron grade of 25.8%.
The inferred mineral resources are 230Mt at 28$/t NSR containing 477kt of copper at a grading of 0.21%, 46Mt of iron, and 200koz of gold at a grading of 0.03g/t.
Mining and Processing Method
Santo Domingo copper-iron-gold mine is an open pit project. The mine plan for the project is based on processing 23.7Mt per year (Mt/y)- 26.3Mt/y of feed with a peak mining rate of 90Mt/y.
In the first year, the plant will have an average production rate of 54.6 tonnes per day (t/d). From second to fifth year, a plant feed of 72,000 t/d of is scheduled for the plant, declining to average 50,000t/d from 16th to 19th year.
There will two pits- the Santo Domingo pit and the Iris Norte pit, which will be developed using conventional drilling, blasting, and loading with electric and hydraulic shovels. The Santo Domingo pit will have eight phases, while the latter will have two.
The mining equipment will include electric shovels, hydraulic shovels, a wheel loader of capacities 57, 42, and 38m3, and 290t trucks.
Drilling rigs, tracked dozers, wheel dozers, motor graders, and a water truck will support the fleet during mining.
The recovery process will undergo crushing, grinding, copper flotation, magnetite recovery, copper dewatering and load-out, magnetite pumping and dewatering, tailings dewatering and storage.
The copper-iron concentrator will be able to process up to 72,000 tonnes per day using Autogenous Grinding (AG) milling, with conventional rougher cell flotation, regrinding and classification.
Jameson Cells will be used in the cleaner, cleaner scalper, cleaner scavenger, and re-cleaner stages. Low Intensity Magnetic Separation process will be used to recover magnetite iron from the copper rougher tailings.
Santo Domingo will produce approximately 106,400 tonnes of copper annually for the first seven years of full operation. The LOM average production will be 68,100 tonnes of copper per year over a period of approximately 19 years.
Annual average iron concentrate production is estimated to be 3.7 million dmt for the first seven years. The figure would be 3.6 million dmt on average annually over the LOM.
Santo Domingo Project Infrastructure
The planned infrastructure of the Santo Domingo Mine comprises tailings storage facility, waste rock storage facilities, a desalination plant, magnetite concentrate and water pipelines, port facilities, and mine stockpile facilities.
High voltage transmission line and accommodation facilities will also be developed.
The plant and the port site will receive high-voltage power via connection to the Chilean national grid, Sistema Eléctrico Nacional (SEN).
The San Lorenzo Substation will be the connection point for the plant and mine. The substation will be located around 9km from the plant in the municipality of Diego de Almagro.
Key Contracts
The 2024 FS of the Santo Domingo Project was prepared by Ausenco Chile, Ausenco Sustainability, and Ausenco Services for Capstone Copper.
Knight Piésold conducted the mining project’s Environmental Impact Study.
Caron Business Solutions provided accounting and financial reporting solutions to Capstone Copper to help the latter manage its operations.
