The proposed process plant is designed to treat approximately 10,000 tpd of mineralized material through a flowsheet incorporating crushing, grinding, gravity concentration, cyanide leaching, carbon-in-pulp adsorption, and gold doré production.
Report context
This technical report for the Great Bear Gold Project, dated 2023, describes a proposed process plant designed by Kinross Gold Corporation and DRA. The plant design is based on metallurgical test work results and derived process design criteria. The report presents a conceptual process flowsheet with key design criteria and equipment specifications for a project life of at least 20 years.
Processing route
Primary Crushing and Stockpile
Run-of-mine mineralized material is delivered by mine trucks to a primary crusher feed bin equipped with a static grizzly. Oversize material is broken by a rock breaker. Material is withdrawn by an apron feeder to a vibrating grizzly screen ahead of the primary jaw crusher. Grizzly screen oversize feeds the jaw crusher. Grizzly screen undersize, jaw crusher product, and apron feeder fines are combined and conveyed to a crushed material stockpile with a total capacity of 30 kt and a live capacity of 8 kt. The stockpile is covered for dust control and weather protection. Three variable-speed apron feeders in a reclaim tunnel withdraw material onto the SAG mill feed conveyor.
Grinding Circuit
The grinding circuit consists of a SAG mill operating in closed circuit with a vibrating discharge screen and pebble crusher. The ball mill operates in closed-circuit classification with a hydrocyclone cluster. SAG mill discharge screen oversize is conveyed to the pebble crusher and returned to SAG mill feed. SAG mill discharge screen undersize, ball mill discharge, and gravity concentrator tails discharge to the cyclone feed pump box. Cyclone underflow reports to the ball mill, with a portion diverted to the gravity concentration circuit. Cyclone overflow flows by gravity to the trash screen before the pre-leach thickener.
Gravity Concentration and Intensive Leach
A portion of the cyclone underflow is diverted to two parallel gravity concentrators preceded by vibrating scalping screens to remove oversized particles above 2 mm. Oversized particles return to the ball mill feed chute. Undersize material flows by gravity to the batch gravity concentrators. Concentrate is flushed into an intensive cyanide leach reactor operating as a batch process. Leached gold in solution is pumped to a dedicated electrowinning cell. Intensive leach tailings are rinsed and pumped to the cyclone feed pump box.
Pre-Leach Thickening, Leaching, and Carbon-in-Pulp
Ball mill cyclone overflow flows by gravity to two pre-leach thickener trash screens. A 25 m diameter pre-leach thickener thickens slurry from 26% to 50% solids. Underflow is pumped to five leach tanks in series, each 18 m diameter by 19 m high, providing approximately 40 hours of leaching residence time. Slurry then passes through a conventional cascade CIP circuit with tanks of 9.1 m diameter by 11.4 m high. Carbon is transferred countercurrent to slurry flow. Loaded carbon from the first CIP tank is separated and sent to the elution circuit. Slurry from the final CIP tank passes through carbon safety screens to recover fine carbon, then pumps to the CIP tailings thickener, cyanide destruction tanks, and desulphurization flotation cells.
Elution, Regeneration, and Gold Room
Loaded carbon undergoes acid washing with dilute hydrochloric acid, rinsing with caustic solution and water, then elution using the Pressure Zadra process. Heated eluate solution containing sodium cyanide and sodium hydroxide recirculates through the elution column and electrowinning cells. Gold and silver plate onto stainless steel mesh cathodes. Elution continues until eluate gold concentration is below 5 ppm. Carbon is rinsed, dewatered, and regenerated in a kiln, then quenched and sized before returning to the CIP circuit. Cathodes are washed to collect sludge, which is filtered, dried, mixed with fluxing agents, and smelted in a barring furnace to produce doré bars.
Tailings Handling
CIP tailings discharge to a 25 m diameter CIP tailings thickener, thickening from 50% to 60% solids. Underflow is diluted and enters two parallel cyanide destruction tanks (7.5 m diameter by 8.5 m height, one-hour retention time) using the SO₂/air process with sodium metabisulphite. Detoxified tailings are pumped to three 200 m³ desulphurization flotation cells in series to remove sulphides. Concentrate goes to a sulphide concentrate management facility, while flotation tailings are thickened (25 m diameter thickener) to 35%–60% solids and pumped to a tailings management facility. A portion of detoxified tailings is planned for paste backfill to the underground mine.
Reagents
Key reagents include sodium cyanide (solid briquettes dissolved to 27% w/w solution), quick lime (slaked and pumped as slurry to pre-leach thickener, leach tanks, and cyanide destruction tanks), granulated activated carbon (6×12 mesh, added via carbon attrition tank), flocculant (batched and dosed to thickener feed wells), sodium hydroxide (50% w/w for elution and intensive leach), hydrochloric acid (33% w/w diluted to 3% for acid wash), sodium metabisulphite (for cyanide destruction), copper sulphate (for cyanide destruction), anti-scalant, calcium chloride (for anti-freezing in stockpile dome), and flotation reagents including MIBC, PAX, and AERO208.
Key reported parameters
| Parameter | Units | Value | Basis |
|---|---|---|---|
| Gold feed grade (design) | g/t | 7.25 | Kinross |
| Silver feed grade (design) | g/t | 2.00 | Kinross |
| Crusher and concentrator throughput capacity (nominal) | t/d | 10,000 | Kinross |
| Crusher and concentrator throughput capacity (nominal) | Mt/y | 3.65 | Kinross |
| Gold recovery (design) | % | 95.9 | Weighted test work results (SGS) |
| Silver recovery (design) | % | 52 | Weighted test work results (SGS) |
| Material specific gravity | , | 2.83 | Weighted test work results (SGS) |
| Bond crusher work index (design) | kWh/t | 19.9 | LP Fault test work (SGS) |
| Bond ball mill work index (design) | kWh/t | 12.0 | Weighted test work results (SGS) |
| Bond abrasion index (design) | g | 0.282 | Weighted test work results (SGS) |
| JK resistance to impact Axb (design) | Axb | 31.8 | Weighted test work results (SGS) |
| Grinding circuit particle size (leach feed, P80 nominal) | µm | 75 | Test work (SGS) |
| Design gravity gold recovery | % | 51 | FLS Model |
| Crusher utilization | % | 70 | DRA/Kinross |
| Concentrator utilization | % | 92 | DRA/Kinross |
| Crushed material stockpile total capacity | t | 30,000 | DRA |
| Elution carbon batch size | t | 10 | Calculated |
Project website: https://www.kinross.com/English/operations/americas/Dixie-Red-Lake/default.aspx
Technical qualifications
This report presents a conceptual process flowsheet and design criteria based on metallurgical test work results. The design is proposed and not yet constructed. Recovery values and design parameters are derived from weighted test work results by SGS and industry benchmarks. The report does not present historical operating data or actual performance data. Test work results are specifically identified as weighted test work results (SGS) or LP Fault test work (SGS). Equipment design is based on process design criteria, equipment reliability, and ease of maintenance considerations. No actual operating performance data are available for this proposed facility.
Source: Great Bear Gold Project, Ontario, Canada, NI 43-101 Technical Report, Kinross Gold Corporation, 2023. Sections 17.1–17.4, Table 17-1.
