Vicuña Project: Three-Stage Copper-Gold Flotation Recovery

Source: Unnamed_Company_7 (2026)
Website: https://www.lundinmining.com/our-portfolio/projects/vicuna-district/

Critical Data

Overview

The Vicuña Project, a major copper-gold development straddling the Argentina-Chile border, is operated by Lundin Mining Corporation and Vicuña Corp. The 2026 Preliminary Economic Assessment (PEA) outlines a phased three-stage processing strategy designed to optimize recovery from the Josemaria and Filo del Sol deposits. The Stage 1 Sulphide Mill employs conventional copper-gold flotation to process sulphide mineralization from Josemaria, featuring primary crushing, grinding, flotation, regrind, and concentrate dewatering. Stage 2 adds a district leaching circuit for oxide mineralization from Filo del Sol, utilizing SX-EW for copper and Merrill-Crowe for gold and silver recovery, along with a SART plant for cyanide regeneration. Stage 3 expands sulphide processing capacity to incorporate deeper Filo del Sol sulphides via a phased approach that includes overland conveying and additional grinding and flotation lines. The significance of this staged development lies in its ability to match processing capacity to evolving resource profiles, achieving an overall copper recovery of 86.3% in Stage 1 and targeting saleable concentrate grades averaging 25.4% copper. The process flowsheet integrates advanced comminution with gearless mill drives, high-rate thickening, and robust tailings management to ensure efficient, sustainable operations.

Key Process Stages

• Stage 1: Primary Crushing and Coarse Material Handling – Two 1,525 mm x 2,260 mm Metso Mk III gyratory crushers (540 t surge pockets each) reduce Run-of-Mine ore to a nominal F80 of 120 mm. Crushed material is conveyed via a 500 m system to an 80,000 t live capacity covered stockpile with 10 hours of live storage per grinding line. Reclaim tunnels with belt feeders feed three SAG mill circuits.
• Stage 2: Comminution – Three parallel grinding lines each consist of a 12.2 m diameter x 7.9 m EGL SAG mill (26 MW gearless drive) and an 8.3 m x 13.7 m EGL ball mill (22 MW gearless drive). SAG mills operate at 15% ball charge (138 mm media) to achieve a T80 of 2,500 µm. Cyclone classification targets a flotation feed P80 of 130 µm at 56% solids. Overall nameplate throughput is 175,000 t/d.
• Stage 3: Rougher & Pyrite Rougher Flotation – Cyclone overflow enters two parallel flotation lines, each with seven 630 m³ copper rougher cells and two 630 m³ pyrite rougher cells. Rougher residence time is ~25 minutes, achieving an average rougher concentrate grade of 2.29% Cu at 95.5% stage recovery (14% mass pull). Pyrite rougher flotation uses a stronger collector to produce low-sulphur tailings.
• Stage 4: Regrind & Cleaning Circuit – Rougher concentrate is pre-cleaned in three 630 m³ cells (3.8% Cu, 97.8% recovery) before entering the regrind circuit with three 3,356 kW vertical stirred mills in closed circuit with cyclones. Target regrind product size is 25–30 µm. The cleaning circuit comprises first cleaners (five 200 m³ cells), cleaner-scavengers (three 300 m³ cells), and second cleaners. Final concentrate averages 23.5–28.9% Cu.
• Stage 5: Concentrate Dewatering and Tailings Thickening – Final concentrate is thickened in a 30 m diameter high-rate thickener to 63% solids, then filtered to 10.9–12% moisture for truck shipment via rotainers. Rougher tailings are thickened in two 100 m diameter high-rate thickeners to 58% solids for low-sulphur TSF. Cleaner tailings (pyrite concentrate, pre-cleaner tails) thicken in a 70 m diameter unit to 48% solids for lined high-sulphur TSF.

Additional Interesting Data and Summary

Beyond Stage 1, the Vicuña Project’s Stage 2 (District Leaching) processes 90,000 t/d at the Filo site, with 60,000 t/d of copper-gold blend material on an on/off heap leach pad and 30,000 t/d of gold oxide on a dedicated ROM pad. The on/off pad operates nine months per year due to winter constraints. Blend material undergoes primary crushing (Metso Mk III gyratory), grizzly screening, acid scrubbing, and secondary crushing (MP1250 cone crusher) to P80 38 mm before stacking on a 550 x 965 m pad (7.5 m height). Leaching uses raffinate at 10 L/m²/h with drip emitters; a 52-day active leach cycle followed by 9-day rinse. SX-EW recovers copper from PLS, while Merrill-Crowe and gold refining recover precious metals. A SART plant regenerates cyanide and precipitates copper. Stage 3 (Sulphide Expansion) introduces Filo del Sol sulphides in two phases: Stage 3A adds primary crushing at Filo and an overland conveyor to Josemaria, modifying existing flotation circuits; Stage 3B expands grinding and flotation capacity with additional mills and cells. Concentrate transport and desalinated water supply infrastructure are included later. Environmental considerations include lined tailings storage facilities for high-sulphur tailings, process water ponds for recycling, and flocculant-assisted thickening to minimize water consumption. The economic impact is significant: Stage 1 alone targets 86.3% copper recovery with concentrate grades up to 28.9% Cu. Sustainability initiatives include variable speed mill drives for energy efficiency, SART for cyanide recovery, and staged construction to align capital deployment with resource development. The future outlook includes potential expansion to higher-grade Filo sulphide zones, with the PEA providing a robust foundation for feasibility studies. The Vicuña Project’s three-stage approach exemplifies adaptive mineral processing design for complex polymetallic deposits, ensuring maximum value extraction while maintaining operational flexibility.

Key Processes: Flotation, Heap Leaching, Cyanidation, Gravity Separation, SAG Mill, Ball Mill, Crushing

Target Commodities: Gold, Silver, Copper, Zinc, Lead