Detour Lake is a large open-pit gold operation in northeastern Ontario, Canada. Its processing plant combines high-capacity crushing and grinding with gravity concentration, leaching and carbon-in-pulp recovery. This profile consolidates MillMatters’ previous Detour Lake circuit summaries and the material changes described in the 2018, 2021 and 2024 technical-report records.
| Operator | Agnico Eagle Mines Limited |
|---|---|
| Location | Ontario, Canada |
| Commodity | Gold |
| Mine type | Open pit; a potential concurrent underground operation is under evaluation |
| Plant route | Crushing, SABC grinding, gravity recovery, leaching, CIP, electrowinning and doré production |
| Original design throughput | 55,000 t/d, approximately 20 Mt/a |
| Demonstrated 2024 rate | 77,022 t/d in Q4 2024, equivalent to approximately 28 Mt/a |
| Current optimization target | 79,450 t/d, approximately 29 Mt/a |
| Profile last reviewed | August 30, 2026 |
Detour Lake processing flowsheet
The flowsheet was designed around competent, abrasive ore and deliberately generous comminution capacity. The plant has subsequently exceeded its original 20 Mt/a design through a combination of equipment upgrades, operating-time improvements and debottlenecking.
1. Primary and secondary crushing
Run-of-mine ore is reduced in a 60 × 113-inch primary gyratory crusher operating in open circuit. Two XL1100 secondary cone crushers, each reported at approximately 1,550 t/h, treat scalped primary-crusher product. The oversized primary and secondary crushing installation was an important design choice because it reduced the risk of starving the grinding plant when treating hard ore.
2. SAG and ball milling
Crushed ore is processed through two grinding lines using SAG and ball mills in closed circuit with hydrocyclones. The SAG mills are approximately 10.7 m × 5.33 m and the ball mills approximately 7.73 m × 12.19 m. Pebble crushing controls critical-size material. The circuit separates the classification target used around grinding from the finer leach-feed target; technical records cite values near 130 µm for classification and approximately 95 µm for leach feed.
3. Gravity concentration
Six Falcon SB5200-BSE centrifugal concentrators treat a portion of cyclone feed. Gravity recovery captures liberated coarse gold before the main leach circuit, reducing the amount of immediately recoverable gold carried into the large downstream inventory.
4. Leaching and carbon-in-pulp
Gravity tails pass to agitated cyanide leaching. The plant has 20 leach tanks of approximately 4,988 m³ each, with reported retention near 29 hours at roughly 50–55% solids. Dissolved gold is recovered in two carousel-type CIP lines, each containing seven approximately 330 m³ tanks. Loaded carbon is acid washed, stripped and regenerated before reuse.
5. Electrowinning, refining and tailings treatment
Gold-bearing solution is treated by electrowinning and smelting to produce doré. Before tailings are discharged to the tailings management area, residual cyanide is destroyed using the INCO SO₂/air process. Pre-leach and pre-detox thickening support water recovery and slurry-density control.
Principal equipment and operating data
| Area | Equipment or parameter | Reported value |
|---|---|---|
| Primary crushing | Gyratory crusher | 60 × 113 inches; approximately 4,200–4,500 t/h |
| Secondary crushing | Two XL1100 cone crushers | Approximately 1,550 t/h each |
| SAG milling | Two SAG mills | Approximately 10.7 × 5.33 m; twin-pinion drives |
| Ball milling | Two ball mills | Approximately 7.73 × 12.19 m |
| Gravity | Falcon concentrators | Six SB5200-BSE units |
| Leaching | Agitated tanks | 20 × approximately 4,988 m³; about 29 hours retention |
| CIP | Carousel adsorption | Two lines; seven approximately 330 m³ tanks per line |
| Carbon regeneration | Kilns | Two units at approximately 10 t/d each |
| Cyanide destruction | SO₂/air tanks | Three × approximately 2,775 m³ |
Throughput and performance
The important Detour Lake story is not a change to the basic recovery route; it is the progressive removal of constraints from a robust original plant. The operation moved from a 20 Mt/a design basis to more than 25 Mt milled in 2023. Agnico Eagle reported a record fourth-quarter 2024 rate of 77,022 t/d, equivalent to approximately 28 Mt/a, while maintaining the existing crushing–grinding–gravity–leach–CIP architecture.
This distinction matters when comparing report years. Later throughput forecasts do not describe separate processing plants. They describe successive operating and capital improvements to the same facility.
What changed between the 2018, 2021 and 2024 reports?
| Report period | Plant position | Material change or conclusion |
|---|---|---|
| 2018 | Original 55,000 t/d design had already been exceeded | Availability, conveyor reliability, grinding wear and CIP capacity were identified as the practical constraints. The focus was moving from proving capacity to sustaining operating time. |
| 2021 | 2020 mill production reached approximately 23.06 Mt | The life-of-mine plan targeted 28 Mt/a through fragmentation improvement, stable crusher feeding, higher SAG utilization and plant debottlenecking. |
| 2024 | 2023 mill production reached approximately 25.4 Mt | The plan added crusher and grinding upgrades, advanced process control and other reliability projects. It also evaluated blending higher-grade underground ore into the existing plant. |
| 2024 operating result | Q4 reached 77,022 t/d, approximately 28 Mt/a annualized | The earlier 28 Mt/a objective became demonstrated performance rather than only a forecast. |
| Current company target | Further optimization toward 79,450 t/d | Agnico Eagle’s current mine page identifies a 29 Mt/a target by 2030. This supersedes earlier schedules that referred to 2028. |
Optimization and potential underground feed
Key throughput initiatives described across the reports include improved blast fragmentation, more consistent choke feeding of the secondary crushers, variable-speed and motor upgrades, changes to SAG mill grates, ball-mill discharge and scalping-screen improvements, advanced process control and machine-learning-supported ore blending.
The 2024 preliminary economic assessment considered concurrent open-pit and underground production. Underground ore would be blended with open-pit feed and processed through the existing plant rather than through a separate concentrator. The study used an underground rate of approximately 11,200 t/d beginning around 2030 and a combined mill basis near 29 Mt/a. Because this remains a development scenario, it should be distinguished from the current operating circuit.
Technical-report library and sources
| Source period | How it is used in this profile |
|---|---|
| 2018 technical report | Original design basis, early ramp-up, operating-time constraints and initial debottlenecking priorities |
| 2021 NI 43-101 technical report | 2020 performance, 28 Mt/a plan, equipment description and life-of-mine assumptions |
| 2024 NI 43-101 technical report and technical study | Updated plant performance, current optimization program and potential underground integration |
| 2024 annual operating results | Confirmation that the plant achieved an annualized 28 Mt/a rate in Q4 2024 |
Additional resources and industry links
- Agnico Eagle: Detour Lake mine profile and current operating information
- Agnico Eagle: 2024 Detour Lake technical-report filing
- Agnico Eagle: 2024 underground plan and mill-optimization study
- Agnico Eagle 2024 Annual Report