Collahuasi is a high-altitude open-pit copper-molybdenum operation in Chile’s Tarapacá Region. The Ujina concentrator uses primary crushing, three SAG-ball grinding lines, rougher flotation, vertical regrinding and multi-stage cleaning to produce a collective copper-molybdenum concentrate. Molybdenum is separated from the copper concentrate at the Punta Patache port facility. This profile consolidates MillMatters’ duplicate 2025 report summaries and updates the expansion schedule through August 2026.
| Owner | Anglo American 44%, Glencore 44%, and a Japanese consortium led by Mitsui 12% |
|---|---|
| Operator | Compañía Minera Doña Inés de Collahuasi (CMDIC) |
| Location | Tarapacá Region, northern Chile; mine and concentrator at approximately 4,200–4,800 m elevation |
| Commodities | Copper and molybdenum |
| Mine type | Open pit |
| Plant route | Primary crushing, SAG-ball grinding, rougher flotation, vertical regrinding, cleaner flotation, concentrate thickening and transport to port |
| Current demonstrated configuration | 170,000 t/d design basis; 2025 technical-report data show approximately 168,000 t/d actual feed |
| Approved debottlenecking stages | Approximately 185,000 t/d during 2026 and 210,000 t/d from late 2027, subject to commissioning and current permit context |
| Profile last reviewed | August 30, 2026 |
Collahuasi processing flowsheet
Collahuasi’s current sulphide concentrator configuration was established by the 2023 expansion from 160,000 to 170,000 t/d. The central change was a fifth ball mill that increased grinding capacity while the overall route remained conventional copper-molybdenum flotation.
1. Primary crushing and coarse-ore storage
Ore from the Rosario pit is reduced in Crusher No. 4, a 60 × 114-inch primary gyratory crusher. Crushed ore is conveyed to the coarse-ore stockpile, which decouples intermittent mine haulage and crushing from the continuously operating grinding plant.
2. Three SAG-ball grinding lines
Grinding lines 1 and 2 each contain a 32 × 13.5 ft SAG mill and one 22 × 36 ft ball mill. Line 3 contains a 40 × 22 ft SAG mill and two 26 × 38 ft ball mills. Pebbles are crushed and recycled, and the ball mills operate in closed circuit with hydrocyclones.
The fifth ball mill installed for the 170,000 t/d upgrade is a 26 × 46.5 ft unit. It receives crushed SAG pebbles and a portion of discharge associated with the other ball-mill circuits, then operates in its own cyclone-classification loop. The technical-report basis cites a primary grind near a P80 of 230 µm.
3. Rougher flotation
Cyclone overflow is conditioned with flotation reagents and distributed among parallel rougher banks using approximately 127 m³ and 180 m³ mechanical cells. Rougher tailings are final concentrator tailings. Additional 300 m³ rougher cells are being introduced in the staged debottlenecking program to maintain recovery as grinding throughput rises.
4. Regrinding and cleaning
Rougher concentrate is classified and reground in a bank of seven 935 kW vertical mills, normally arranged as four duty and three standby units. The fine product passes through first- and second-cleaner stages plus cleaner-scavenger treatment. Column and Jameson cells perform final upgrading; Jameson-cell tailings recycle to the first cleaner, while combined column and Jameson concentrate becomes the final collective copper-molybdenum product.
5. Concentrate thickening and holding
The collective concentrate is thickened in two approximately 40 m diameter thickeners with support from an approximately 43 m clarifier. Thickened concentrate is stored in three approximately 1,000 m³ holding tanks before it enters the pipeline to the coastal port complex.
Principal equipment and reported operating data
| Area | Equipment or parameter | Reported value |
|---|---|---|
| Current concentrator | 170 kt/d configuration | Established by the 2023 expansion; 2025 actual feed approximately 168 kt/d |
| Primary crushing | Crusher No. 4 gyratory | 60 × 114 inches |
| Grinding lines 1 and 2 | Two SAG-ball lines | Each: 32 × 13.5 ft SAG and 22 × 36 ft ball mill |
| Grinding line 3 | Large SAG with two ball mills | 40 × 22 ft SAG and two 26 × 38 ft ball mills |
| Fifth ball mill | Expansion mill | 26 × 46.5 ft; installed for the 170 kt/d configuration |
| Primary grind | Nominal cyclone-overflow target | P80 approximately 230 µm |
| Rougher flotation | Parallel mechanical-cell banks | 127 m³ and 180 m³ cells; staged expansion adds 300 m³ cells |
| Regrinding | Vertical mills | Seven × 935 kW; four duty and three standby |
| Cleaning | Mechanical, column and Jameson flotation | Two cleaner stages plus cleaner scavenging and final cleaning |
| Concentrate thickening | Thickeners and clarifier | Two × approximately 40 m thickeners and one × approximately 43 m clarifier |
| Concentrate storage | Holding tanks | Three × approximately 1,000 m³ |
Equipment values describe the 170 kt/d technical-report configuration. Expansion equipment should not be treated as fully commissioned until the operator confirms operation at the new rate.
Concentrate transport and port processing
Ujina produces a combined copper-molybdenum concentrate rather than two saleable products. After thickening, the slurry is pumped through the concentrate pipeline to Punta Patache. At the port, the concentrate is received and thickened, molybdenum is separated by flotation, and the two products are dewatered for shipment.
The 210 kt/d program includes a new approximately 60 m receiving thickener, a desliming stage, an additional molybdenum-separation flotation circuit sized for about 2,100 t/d of collective concentrate, replacement of molybdenum filtration and drying equipment, and an extension of the No. 2 copper-concentrate storage shed. The technical report notes that parts of the molybdenum expansion still require separate approval and are not all included in the current life-of-mine plan.
Throughput, grade and recovery
Technical-report statistics show why throughput and recovery should be read together. Actual plant feed rose from approximately 54.1 Mt in 2019 to 60.1 Mt in 2024. The 2024 average was about 165,000 t/d. Preliminary 2025 data in the November 2025 report indicate approximately 61.1 Mt, or 168,000 t/d, close to the 170,000 t/d configuration.
Over the same period, the ore blend became more challenging. The reported average copper feed grade fell from 1.19% in 2019 to 1.15% in 2024 and approximately 0.92% in the preliminary 2025 figures. Actual copper recovery was 81.1% in 2024 and approximately 82.8% in the preliminary 2025 data, compared with higher recoveries earlier in the period. Anglo American’s first-quarter 2026 update reported recovery of 71.8% while lower-grade stockpiles were being processed during a mine-phase transition. This is a feed-quality effect as well as a plant-capacity issue.
Expansion from 170 to 210 kt/d
| Stage | Status at August 30, 2026 | Principal scope |
|---|---|---|
| 170 kt/d | Operating reference configuration | Fifth ball mill and associated grinding/flotation changes completed in 2023 |
| PG3A to approximately 185 kt/d | Approved; commissioning scheduled for Q3 2026, but the new rate is not treated here as demonstrated | Refurbished third primary crusher and additional flotation capacity |
| PG210 to 210 kt/d | Approved investment; first production targeted from late 2027 | Ore-conveying upgrades, further rougher cells, water and electrical systems, and port debottlenecking |
| Fourth processing line / larger growth concept | Under study and outside the current life-of-mine plan | Potential separate processing capacity and mine expansion; subject to studies, permitting and approvals |
One former MillMatters page described PG3A as a June 2026 start and the 210 kt/d stage as a 2028 event. Current company sources instead schedule PG3A commissioning during the third quarter of 2026 and expect the 210 kt/d stage to contribute from late 2027. The life-of-mine schedule may model the full 210 kt/d rate in 2028, but that modelling year is not the same as first production.
Desalination and current permit context
The C20+ infrastructure program includes a desalination plant designed to deliver approximately 1,050 L/s and a roughly 194 km pumping system from the coast to the high-altitude mine. Collahuasi reports that about 80% of operational water demand is already supplied through reuse and recirculation, but desalinated water is important to lowering long-term continental-water use and supporting growth.
In May 2026, Chile’s Second Environmental Tribunal set aside the 2021 environmental authorization for review of two aspects concerning a local community and the marine environment. Anglo American said the immediate issue related to desalination infrastructure rather than the whole Collahuasi environmental assessment and did not expect an immediate production impact because alternative water sources were available. Its July 2026 results discussion said the consultation process would need to be reset and that restoring the desalination project remained important for the longer term. Expansion schedules should therefore be read as current company targets subject to this evolving permit process.
Technical-report library and sources
| Source period | How it is used in this profile |
|---|---|
| SRK Collahuasi Technical Report, November 2025 | 170 kt/d flowsheet, equipment, historical operating statistics, PG3A/PG210 scope and larger growth concept |
| Collahuasi 2024 Sustainability Report | Operator’s staged Ujina Growth Project scope and commissioning schedule |
| Anglo American 2025 full-year results | Approved 185 and 210 kt/d investments and expected production timing |
| Anglo American Q1 and Q2 2026 updates | Current feed, recovery, water and operating context |
| Anglo American May and July 2026 permit updates | Current desalination authorization and consultation context |
Additional resources and industry links
- Collahuasi: official company and operation website
- Collahuasi sustainability-report library
- Teck December 2025 management circular: Collahuasi technical-report context (PDF)
- Anglo American Q2 2026 production report
- Anglo American May 2026 Collahuasi environmental-permit update
- MillMatters: Grinding mills in mineral processing
- MillMatters: Hydrocyclones and classification
- MillMatters: Dewatering equipment and circuit design
