Overview
The Casa Berardi Mine operates a gold processing facility using a Carbon-in-Leach (CIL) circuit to address preg-robbing effects from graphitic carbon in the ore. The plant, operational since 2015, has undergone multiple upgrades to optimize throughput and recovery. The circuit integrates crushing, grinding, gravity concentration, and cyanide leaching with a design capacity of 1.4 million tonnes annually.
Key Process Stages
- Crushing: Ore passes through a static grizzly (500×500 mm), scalping screen (89 mm), and jaw crusher (762×1400 mm) before storage in a 3,000-tonne bin.
- Grinding: SAG mill (5.5m x 2.7m, 1,130 kW) operates in closed circuit with a vibrating screen (5×16 mm). Ball mill (4.0m x 5.3m, 1,325 kW) works with primary (660 mm) and secondary cyclones (250 mm) to achieve P80 of 91.5 µm.
- Gravity Circuit: Two Knelson concentrators (762 mm) recover 36.5% of gold, with concentrate processed in an intensive leach reactor (Gekko ILR).
- CIL Circuit: Seven 700 m³ tanks with 20-hour residence time, 24 g/L carbon concentration, and 450 ppm NaCN. Pulp density maintained at 50% solids.
- Carbon Management: Loaded carbon undergoes acid washing, elution (ZADRA process at 135°C), and regeneration in a kiln (0.76m x 7.3m, 350 kW).
- Gold Recovery: Electrowinning cells (4.53 m³) process pregnant solution, with gold sludge smelted in a 750-lb induction furnace.
Critical Data
| Parameter | Value | Unit |
|---|---|---|
| Throughput (2019) | 1.4 | Mt/a |
| Feed Grade | 2.8 | g/t Au |
| Overall Recovery | 86.7% | – |
| Grinding P80 | 91.5 | µm |
| CIL Cyanide Concentration | 450 | ppm |
| Reagent Consumption (NaCN) | 0.55 | kg/t |
| Tailings Cyanide (WAD) | <10 | ppm |
Major Equipment
- SAG Mill: 5.5m diameter x 2.7m EGL, 1,130 kW motor
- Ball Mill: 4.0m diameter x 5.3m length, 1,325 kW motor
- Production Thickener: 34m diameter high-rate type
- Elution Vessel: 1.68m diameter, 5.5t carbon capacity
Recent Upgrades (2017-2018)
- Increased SAG mill discharge grate area (3.1% → 4.0%)
- Ball mill pinion replacement for higher power draw
- New NKM screens in CIL tanks (2017)
- Enhanced cyanide destruction system (2019)
Technical report and processing history
The following archived source profiles have been consolidated here to preserve the project’s processing history and study context.
Casa Berardi — 2024 Technical Report (Recovery Methods)
Casa Berardi — 2024 Technical Report (Recovery Methods)
| Company | Hecla |
| Date | 2024 |
| Region | Quebec, Canada |
| Commodities | Gold |
Executive Summary
The Casa Berardi mill currently processes 3,730 tons per day (tpd) with a future maximum production capacity of 4,400 tpd. Gold extraction is performed using a combination of Gravity Concentration and Carbon In Leach (CIL) processes. These methods were specifically selected to optimize the recovery of free gold and reduce the preg-robbing effect caused by graphitic carbon present in the ore. The plant configuration is based on the current facility as of December 31, 2023, utilizing historical performance data and metallurgical test results to predict recovery.
The processing circuit begins with ore hauling from the West Mine headframe complex and open pit to a crusher dump pocket equipped with a static grizzly and pneumatic hammer. Crushed ore is stored in a bin before being conveyed to a SAG mill operating in closed circuit with a SAG screen. The ground ore is then processed through a ball mill and cyclone cluster. The cyclone underflow is diverted to either the gravity circuit or returned to the ball mill, while the overflow reports to a production thickener.
The gravity circuit utilizes Knelson concentrators and an Intensive Leach Reactor (ILR) to recover high-grade gold, which is then sent to electrowinning. The main CIL circuit consists of seven tanks in series, using activated carbon to adsorb gold from the pulp. The carbon circuit employs the Zadra process for elution, followed by electrowinning to produce gold sludge. Tailings are treated for cyanide destruction and arsenic reduction before disposal or paste backfill. The plant requires approximately 7MW of power and 2.3 million cubic meters of water annually.
Website: https://orezone.com/press-releases/orezone-gold-announces-transformational-expansion-into-canada-with-the-acquisition-of-the-casa-berardi-gold-mine/
Report Date: 2024
Region: Quebec, Canada
Project Status:
Commodity: Gold
Throughput:
Mine Life:
Mine Type:
Ore type:
Casa Berardi Mine: Gold Recovery via CIL Processing
Overview
The Casa Berardi Mine operates a gold processing facility using a Carbon-in-Leach (CIL) circuit to counteract preg-robbing effects from graphitic carbon in the ore. The plant, operational since 2019, integrates crushing, grinding, gravity concentration, and cyanide leaching to achieve an average gold recovery of 86.7%.
Key Process Stages
- Crushing: Ore passes through a grizzly screen, jaw crusher (762mm x 1400mm), and 3,000-tonne storage bin.
- Grinding: SAG mill (5.5m x 2.7m, 1,130 kW) and ball mill (4.0m x 5.3m, 1,325 kW) achieve a P80 of 91.5 µm.
- Gravity Circuit: Two Knelson concentrators (762mm) recover 36.5% of gold, with concentrate processed in an intensive leach reactor (Gekko ILR).
- CIL Circuit: Seven 700m³ tanks with 20-hour residence time, 24 g/L carbon concentration, and 450 ppm NaCN.
- Elution & Electrowinning: ZADRA process at 135°C/380 kPa produces gold sludge smelted into doré bars.
Critical Data
| Parameter | Value | Unit |
|---|---|---|
| Throughput | 1.4 | Mt/a |
| Feed Grade | 2.8 | g/t Au |
| Grinding P80 | 91.5 | µm |
| Cyanide Consumption | 0.55 | kg/t |
| Carbon Concentration | 24 | g/L |
Recent Upgrades
Key 2017-2018 optimizations included SAG mill liner redesign, ball size adjustments (125mm), and increased discharge grate area (4.0%). These raised throughput from 1.2 Mt/a (2015) to 1.4 Mt/a (2019).
