Operations
Once in production, Eskay Creek will operate as a conventional open-pit mining operation with a 12-year mine life.
Mining
The Eskay Creek mine plan assumes conventional open pit mining methods and the use of conventional equipment. Two open pits are planned, a larger northern pit, and smaller southern pit.
| Strip ratio (waste:ore) | 7.98:1 |
| Total material mined (excluding rehandle) (Mt) | 357.7 |
| Total ore mined (Mt) | 39.8 |
Processing
The processing plant facilities will consist of crushing, grinding and flotation circuits designed to liberate and recover gold from the ROM ore. Flotation concentrate will then be thickened, filtered, dried, and stockpiled at the process plant prior to loading into haul trucks for transport.
Drag image or use arrows below to see full schematic
The Project will be constructed in two phases:
Initial operation
Initial operation of 3.0 Mt/a for Years 1–5, which comprises:
- Single-stage crushing circuit (jaw), fed from the open pit mine
- Coarse ore bin with reclaim system, fed from an overland conveyor
- Primary grinding including a semi-autogenous grinding (SAG) mill, pebble crusher (installed in year 3), and ball mill in closed circuit with hydrocyclones
- Further classification via one stage of hydrocyclones and tertiary grinding
- Rougher flotation with concentrate regrind and two stages of cleaning
- Scavenger flotation for recovery of cleaner tails
- Concentrate thickening, filtration, drying and storage
- Concentrate load-out by way of front-end loader filling concentrate transportation
- Final tailings pumping to the TSF
Expansion
Expansion to 3.5 Mt/a for the remaining LOM, which includes the initial equipment with the addition of the following installed for Year 6 to Year 12 operations:
- Several key pieces of equipment in the initial phase are already sized to accommodate the final 3.5 Mt/a throughput, including the jaw crusher, SAG and ball mills, and thickener
- Additional operating cyclones and concentrate filter plates
- Upgraded process pumps and piping
- Retrofit larger motor size on SAG, ball and tertiary grind mills (if required, pending further sampling and testwork).
Cash Costs and All-in Sustaining Costs
The high-grade nature of Eskay Creek’s orebody translates into industry leading all-in sustaining costs and cash costs.
| LOM cash cost (US$/oz) net of silver by-product | 133 |
| LOM cash cost (US$/oz AuEq) co-product | 568 |
| LOM AISC (US$/oz Au) net of silver by-product | 300 |
| LOM AISC (US$/oz AuEq) co-product | 687 |
Estimates from 2023 Definitive Feasibility Study, using base case prices of US$1,800/oz gold & $23/oz silver
Reserves and Resources
Eskay Creek Reserves & Resources – Pit-constrained (as of December 31, 2023)
| Tonnes (Mt) | Au (gpt) | Ag (gpt) | AuEq (gpt) | Au oz (Moz) | Ag oz (Moz) | AuEq Oz (Moz) | |
|---|---|---|---|---|---|---|---|
| Mineral Reserves | |||||||
| Proven | 28.0 | 3.0 | 80.9 | 4.1 | 2.7 | 72.7 | 3.7 |
| Probable | 11.9 | 1.8 | 40.1 | 2.3 | 0.7 | 15.3 | 0.9 |
| Total Proven & Probable Reserves | 39.8 | 2.6 | 68.7 | 3.6 | 3.3 | 88.0 | 4.6 |
| Mineral Resources | |||||||
| Measured | 27.8 | 3.3 | 87.9 | 4.6 | 3.0 | 78.6 | 4.1 |
| Indicated | 22.3 | 1.6 | 32.0 | 2.1 | 1.1 | 22.9 | 1.5 |
| Total Measured & Indicated resources | 50.1 | 2.6 | 63.0 | 3.4 | 4.1 | 101.4 | 5.5 |
| Inferred Resources | 0.65 | 1.5 | 32.4 | 1.9 | 0.03 | 0.7 | 0.04 |
Notes for Reserves:
- Mineral Resources are reported at the point of delivery to the process plant, using the 2014 CIM Definition Standards, with an effective date of November 14, 2023. The Qualified Person for the estimate is Ms. Terre Lane, MMSA QP, a GRE employee.
- Mineral Resources are constrained within an open pit shell that uses the following assumptions: gold price of US$1,700/oz, Mineral Reserves are stated within the final design pit based on a US$1,800/oz gold price and US$23.00/oz silver price. Gold and silver recoveries were 83% and 91%, respectively during the LOM scheduling. An NSR cut-off of C$24.45/t was used to estimate Mineral Reserves based on preliminary processing costs of $18.22/t ore processed and G&A costs of C$6.23/t ore processed. Final operating costs within the pit design were C$2.96/t mined, with associated process costs of C$19.16/t ore processed, G&A costs of C$5.69/t ore processed and water treatment costs of C$2.50/t ore processed. Pit slope inter-ramp angles ranged from 26–51°.
- Mineral Reserves are reported at a net smelter return cut-off of C$24.45/t, using the equation AuEq = ((Au (g/t) * 1,800 * 0.83) + (Ag (g/t)* 23 * 0.91))/(1,800 * 0.83), and inputs of processing costs of C$18.22/t ore processed and G&A costs of C$6.23/t ore processed.
- Numbers have been rounded and may not sum.
Notes for Resources:
- Mineral Resources are reported insitu, using the 2014 CIM Definition Standards, with an effective date of June 20, 2023. The Qualified Person for the estimate is Ms. Terre Lane, MMSA QP, a GRE employee.
- Mineral Resources are reported inclusive of those Mineral Resources converted to Mineral Reserves. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
- Mineral Resources are constrained within a conceptual open pit shell that uses the following assumptions: gold price of US$1,700/oz, silver price of US$23/oz; metallurgical recoveries of 84% for gold and 88% for silver; reference mining cost of US$3.00/t mined; mining dilution of 5%; mining recovery of 95%; processing cost of US$15.50/t processed; general and administrative costs of US$6.00/t processed; transportation and refining costs of US$18.5/oz Au and US$7/oz Ag; and overall pit slope angles of 45°.
- Mineral Resources are reported at a cut-off grade of 0.7 g/t AuEq, using the equation AuEq = ((Au (g/t) * 1,700 * 0.84)+ (Ag (g/t)* 23 * 0.88))/(1,700 * 0.84).
- Numbers have been rounded and may not sum.
Eskay Creek Resources – Underground (as of December 31, 2023)
| Tonnes (Kt) | Au (gpt) | Ag (gpt) | AuEq (gpt) | Au oz (Koz) | Ag oz (Koz) | AuEq Oz (Koz) | |
|---|---|---|---|---|---|---|---|
| Mineral Resources | |||||||
| Measured | 834 | 5.3 | 142.6 | 7.3 | 142 | 3,830 | 196 |
| Indicated | 988 | 4.1 | 55.7 | 4.9 | 131 | 1,766 | 156 |
| Total Measured & Indicated Resources | 1,821 | 4.7 | 95.6 | 6.0 | 273 | 5,699 | 352 |
| Inferred Resources | 272 | 4.2 | 25.4 | 4.6 | 37 | 222 | 40 |
Notes to Accompany Mineral Resources Potentially Amenable to Underground Mining Methods:
- Mineral Resources are reported insitu, using the 2014 CIM Definition Standards, with an effective date of June 20, 2023. The Qualified Person for the estimate is Ms. Terre Lane, MMSA QP, SME Registered Member, a GRE employee.
- CIM Definition Standards, with an effective date of June 20, 2023. The Qualified Person for the estimate is Ms. Terre Lane, MMSA QP, a GRE employee.
- Mineral Resources are reported inclusive of those Mineral Resources converted to Mineral Reserves. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
- Mineral Resources are constrained within stope-optimized shapes that use the following assumptions: gold price of US$1,700/oz, silver price of US$23/oz; metallurgical recoveries of 84% for gold and 88% for silver; reference mining cost of US$100/t mined; processing cost of US$25/t processed; general and administrative costs of US$12/t processed; transportation and refining costs of US$18.50/oz Au and US$7/oz Ag, and a mining recovery of 95%.
- Mineral Resources are reported at a cut-off grade of 3.2 g/t AuEq, using the equation AuEq = ((Au (g/t) * 1,700 * 0.84)+ (Ag (g/t)* 23 * 0.88))/(1,700 * 0.84).
- Numbers have been rounded and may not sum.
