The PEA evaluates a concentrator processing 35,000 tpd of sulfide ore through SABC-A grinding, seawater flotation, and high-density tailings thickening.
Report context
This technical report for the Domeyko Sulfuros project, dated January 23, 2026, documents the preliminary economic assessment (PEA) prepared by SRK Consulting (Chile) SpA. The Recovery Methods section describes the proposed concentrator plant configuration and process design based on the mine plan, metallurgical testwork, vendor data, industry standards, and benchmarking of similar Chilean operations. The report states that the term "ore" is used solely to describe material scheduled for processing in the conceptual mine plan and does not imply the declaration of Mineral Reserves as defined by NI 43-101.
Processing route
General Process Scenario
The concentrator plant was evaluated in a SAG production line scenario at a 150 µm grind size. For tailings processing, high-density tailings were selected over conventional tailings based on optimizing seawater consumption through reduced make-up and on the technology's sustainability and permitting advantages. Due to water scarcity in the area, untreated seawater was adopted as the primary water supply source, supported by the plant's proximity to the coast, benchmarking of Chilean companies using untreated seawater, and comparative tests between seawater and freshwater indicating no differences in rougher copper and gold recovery.
Crushing
Ore from the mine, with a controlled ROM particle size distribution, is fed to a primary gyratory crusher (42"x55", 450 kW) at 35,000 tpd. The crusher product is smaller than 8 inches, with a P80 of 4 inches. An intermediate stockpile with a live capacity of 35,000 tons for a 24-hour buffer is included. The crushing area utilization is 70%, representing 16.6 hours of runtime. The crusher feed rate is 2,083 tph with a 5" setting; maximum equipment capacity is 3,300 tph.
Grinding
The grinding circuit operates with a SAG mill in series with a single-unit ball mill and a pebble-crushing circuit with recirculation to the SAG mill (SABC-A type circuit). The pebble crusher operates in an open circuit to obtain a product with a P80 of 12 mm. The ball mill operates in a closed circuit with two hydrocyclone banks to obtain a ground product with a P80 of 150 µm. Grinding area utilization is 92%, representing 22.08 hours of runtime.
The SAG circuit was sized using JKSimMet simulation, yielding a 36'x19' SAG mill with 11,500 kW power demand and 12,500 kW motor power, feed rate of 1,585 t/h, energy consumption of 7.25 kWh/t, and pebble production of 21%. The correlation between the Axb parameter (42) and energy consumption, obtained from benchmarking SAG operations, forecasts 7-8 kWh/t for an ore with this Axb value in a standard SABC-A circuit. The Domeyko ore falls on the borderline between hard and medium-hardness ores in terms of Axb value.
The ball mill was sized using Bond's methodology, yielding a 26'x44' ball mill with 13,900 kW power demand and 16,000 kW motor power, feed rate of 1,585 t/h, and energy consumption of 8.77 kWh/t. The hydrocyclone classification system requires two clusters of 10 26" cyclones suitable for fine separation down to 150 µm.
Flotation
The flotation plant comprises rougher, regrinding, cleaner, and scavenger stages. The rougher stage design was based on flotation tests performed on nine representative samples from the resources, using seawater with a particle size between 106 µm and 212 µm. Flotation time for the rougher stage was defined at 30 minutes, based on 15-minute flotation tests and a Plant/Laboratory scaling factor of 2.0. A rougher flotation row comprising six 300 m³ tank cells was selected to achieve 92% copper recovery at this stage.
The cleaner stage design was primarily based on benchmarking data, as testing of this stage is ongoing. Jameson pneumatic cells were selected for their greater efficiency in processing fine particles, with two cleaning stages. The objective of the Jameson cell is to produce a final concentrate with grades exceeding 26.5% Cu from ores with average grades of 0.40% Cu, primarily chalcopyrite, in a seawater environment where lime use as a pyrite depressant is restricted and where some Domeyko ores with higher phyllosilicate content could contaminate concentrates.
The main equipment in this area includes a 2,000 kW Vertimill VTM-3000 for regrinding, Jameson pneumatic cells for primary and secondary cleaning, and 100 m³ scavenger cells. The flotation stage has a 92% utilization rate.
Concentrate Handling
Concentrate from the flotation plant is sent to a preliminary thickener and storage before filtration. Concentrate is filtered to achieve 9% moisture using a Larox horizontal filter press. During this stage, the concentrate is washed with desalinated water to remove residual saltwater containing chlorine and sodium. Main equipment comprises a 10 m-diameter Hi-rate thickener and two 90 m² horizontal pressure Larox filters, suitable for an average production rate of 30 t/h, equivalent to 660 t/d. A reverse osmosis plant provides desalinated water for concentrate washing.
Filtered concentrates are stored in a closed stockpile with a 7-day capacity of 5,000 tons. Using two front-end loaders, concentrate is loaded onto 30-ton trucks for transport to nearby shipping ports.
Tailings Thickening
Tailings from the flotation plant, containing 32% solids, are sent to the tailings storage area located 13 km away via a conveying system with centrifugal pumps. Three high-density tailings thickeners, 45 m in diameter, are located in the storage area to achieve a solids concentration of 65%. High-torque thickeners with diameters less than 45 m process slurries with a yield stress of 100-150 pascals. Thickened tailings are sent to the tailings storage area through a pipeline system with separate spigots and low-energy slurry distribution to facilitate placement in thin layers.
Water Management
Seawater supplied from the coast is stored in a seawater pond. Water recovered from the high-density thickeners is collected in a process water pond in the tailings area, from where it is returned to the plant's process water pond and reinjected into the concentrator's process water loop. This pond also collects filtered water from the concentrate.
Key reported parameters
| Parameter | Unit | Value | Basis |
|---|---|---|---|
| Nominal production | tpd | 35,000 | Design |
| Annual processing capacity | ktpy | 12,775 | Design |
| Plant utilization | % | 92.0 | Design |
| Average Cu grade (LOM) | % | 0.35 | Mine plan |
| Average Au grade (LOM) | ppm | 0.25 | Mine plan |
| Cu grade first 5 years | % | 0.40 | Mine plan |
| Au grade first 5 years | ppm | 0.31 | Mine plan |
| Target grind size P80 | µm | 150 | Design |
| Cu recovery (overall) | % | 88.21 | Mine plan (LOM) |
| Au recovery (overall) | % | 64.61 | Mine plan (LOM) |
| Rougher Cu recovery | % | 92 | Testwork |
| Cu concentrate grade | % | 26.5 | Design criteria |
| Concentrate moisture | % | 9 | Design |
| Tailings solids concentration | % | 65 | Design |
| Seawater consumption | m³/t | 0.6 | Design |
| SAG mill dimensions | ft | 36'x19' | Design calculation |
| SAG mill motor power | kW | 12,500 | Design calculation |
| SAG mill energy consumption | kWh/t | 7.25 | Design calculation |
| Ball mill dimensions | ft | 26'x44' | Design calculation |
| Ball mill motor power | kW | 16,000 | Design calculation |
| Ball mill energy consumption | kWh/t | 8.77 | Design calculation |
| Rougher cells | Qty x m³ | 6 x 300 | Design |
| Regrind mill | Type | Vertimill VTM-3000 | Design |
| Cleaner cells | Type | Jameson | Design |
| Total installed power | MW | 42.9 | Design |
| Total equipment | Qty | 82 | Design |
Project website: https://www.scribd.com/document/1000456133/R-05-2898-01-SRK-ABR-20260123-RevD
Technical qualifications
The report includes several specific limitations. The cleaner stage design was primarily based on benchmarking data, as testing of this stage is ongoing. The report states that the selection of reagents needs further study to achieve high recovery in the cleaner stage due to challenges posed by pyrite depression and phyllosilicates in a seawater environment. The impact of seawater on equipment maintenance must also be considered, given corrosion caused by chlorine on metal parts and coatings. The term "ore" is used solely to describe material scheduled for processing in the conceptual mine plan and does not imply the declaration of Mineral Reserves as defined by NI 43-101.
Source: SRK Consulting (Chile) SpA. Technical Report NI 43-101 – PEA Domeyko Sulfuros, Summary Rev. D, January 23, 2026. Relevant sections: 1.14 Recovery Methods and 17 Recovery Methods.
