Overview
Stage | Pre-Feasibility |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Longhole stoping
- Longitudinal retreat
- Cemented rockfill
- Unconsolidated hydraulic fill
|
Mine Life | 6.5 years (as of Jan 1, 2023) |
Wheeler River is the largest undeveloped uranium project in the eastern portion of the Athabasca Basin region in northern Saskatchewan, Canada. The project hosts two high-grade uranium deposits: Phoenix and Gryphon.
In mid-2023, a Feasibility Study was completed for Wheeler River’s Phoenix deposit as an ISR mining operation, and an update to the previously prepared 2018 Pre-Feasibility study was completed for Wheeler River’s Gryphon deposit as a conventional underground mining operation.
Production from the Gryphon operation is assumed to be processed at the 22.5% Denison-owned McClean Lake processing plant, which is located in the northeastern portion of the Athabasca Basin region.
At this time, Denison has not made a decision to advance Gryphon. While the project may benefit from certain infrastructure associated with the development of Phoenix, Gryphon is currently considered a standalone project. |
Source:
p. 1
The parties to the Wheeler River Joint Venture are Denison (operator) and JCU (Canada) Exploration Company Limited (“JCU”). Denison has an effective 95% ownership interest in the Wheeler River project (90% directly, and 5% indirectly through a 50% ownership in JCU).
Uranium Energy Corp. has an effective 5% ownership interest in the Wheeler River project through a 50% ownership in JCU.
Contractors
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Summary:
The Phoenix and Gryphon deposits are classified as an Athabasca Basin unconformity-associated (also unconformity-related and -type) uranium deposit. Gryphon is primarily hosted in the basement rocks, with minor portions of the deposit situated at the unconformity.
The geology of the Gryphon deposit comprises highly deformed crystalline basement rocks overlain by the relatively undeformed Athabasca sandstone. At the Gryphon deposit, the thickness of the Athabasca sandstone cover ranges from 480 m in the southeast to 540 m in the northwest. The unconformity surface down-drops in a series of steps to the northwest. There is approximately 60 m of vertical displacement over 250 m across strike.
Four major basement lithological units have been defined at Gryphon which dip moderately to the southeast:
• Upper Graphite – The Upper Graphite is approximately 110 m thick, occurs furthest stratigraphically to the southeast, and is located hangingwall to the mineralization. The A and E series of mineralized lenses occur at the base of the unit along a major fault zone, the G-Fault. This pelitic gneiss unit averages 5% to 8% graphite in the upper portion of the unit grading to 10% to 15% in the lower portion of the unit. The unit is well foliated and strikes at 022° dipping at 50° to the southeast.
• Quartz-Pegmatite Assemblage – located stratigraphically below the Upper Graphite and interpreted to be a zone of silicification either pre- or syn-mineraliza ........
Mining Methods
- Longhole stoping
- Longitudinal retreat
- Cemented rockfill
- Unconsolidated hydraulic fill
Summary:
The mine plan allows Gryphon to be accessed from surface via the production shaft and the ventilation shaft, to support underground development and production. Heated fresh air will be delivered via the production shaft, with return air exhausted up the ventilation shaft.
Underground production will be from the longhole stoping mining method, primarily longitudinal retreat. Mined stopes will be backfilled using a combination of rockfill, CRF, and hydraulic fill. A minimum 25 m permanent pillar will be left below the unconformity. The mine has been divided into five mining blocks, E Zone, Lower D, Upper and Lower Main, and Upper SW. Each mining block will be mined from the bottom up. Ore will be truck hauled to a rockbreaker/grizzly station and hoisted to surface. The mine is expected to produce approximately 605 t/d of ore and an average of 330 t/d of waste rock during the steady-state operating period.
The Gryphon Project schedule includes approximately six years of pre-production and six years of production at an average mining rate of ~600 t/d ore and 330 t/d waste rock equating to an average of~9 Mlb/a U3O8. Estimated LOM production totals 1.257 Mt of mill feed at an average grade of 1.8% U3O8 containing 49.7 Mlb of U3O8.
Primary access to the deposit will be via a production shaft connecting surface to the main shaft station at 500 Level. The shaft will be used to transport personnel and materials underground, to hoist blasted material to ........
Flow Sheet:
Mineral processing for Gryphon production is based on processing at the McClean Lake mill.
The mill is currently configured to be fed from either the ore stockpile and grinding circuit or from the ore slurry receiving facility, which is currently used to receive high-grade material from Cigar Lake.
The grinding circuit, consisting of a SAG and ball mill, is currently not in service, and is available to the Gryphon feed.
Gryphon ore will be reclaimed from the ore pad by front end loader and transferred to the existing grizzly. The existing grinding circuit will be utilized with no major modifications expected. It is anticipated that the grinding circuit will operate at ~30 t/h, 24 h/d.
Gryphon ore will be metallurgically sampled, and then transferred from the grinding circuit to two existing storage Pachucas in the leaching circuit, providing four hours of residence time.
Cost allowances have been included for the following:
• refurbishing the SAG and ball mills and optimizing them for Gryphon operation;
• installing a variable frequency drive (VFD) and tramp material protection, and making minor piping modifications;
• refurbishing the retaining wall of the ore dump pocket.
Flow Sheet:
Summary:
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Source:
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Projected Production:
Commodity | Units | Avg. Annual | LOM |
U3O8
|
M lbs
| 7.6 | 49 |
All production numbers are expressed as yellow cake.
Operational Metrics:
Metrics | |
Daily ore mining rate
| ...... |
Daily mining rate
| ...... |
Daily waste mining rate
| ...... |
Hourly processing rate
| ...... |
Annual production capacity
| ...... |
Annual processing rate
| ...... |
Ore tonnes mined, LOM
| ...... |
* According to 2023 study.
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Reserves at June 26, 2023:
Mineral reserves for the Gryphon deposit are estimated at a cut-off grade of 0.58% U3O8 based on longhole mining using a long-term uranium price of US$50/lb and a US$/CA$ exchange rate of 0.8.
Mineral resources for the Gryphon deposit are constrained by underground mining shapes using a minimum mining width of 2 m and an incremental cut-off grade of 0.2% U3O8.
Mineral Resources are reported inclusive of Mineral Reserves.
Category | Tonnage | Commodity | Grade | Contained Metal |
Probable
|
1,257,000 t
|
U3O8
|
1.8 %
|
49,700 k lbs
|
Indicated
|
1,643,000 t
|
U3O8
|
1.7 %
|
61,900 k lbs
|
Inferred
|
73,000 t
|
U3O8
|
1.2 %
|
1,900 k lbs
|
Corporate Filings & Presentations:
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