Overview
Stage | Restarting |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Mechanized Cut & Fill
- Post Pillar Cut & Fill
- Sub-level stoping
- Avoca
- Sub-level Retreat
- Longitudinal retreat
- Cemented backfill
|
Mine Life | 2032 |
AeroVision Mag-Drone magnetometer surveys were conducted on the Halfmile Lake Central and California Lake Mineral Claims as part of the required exploration work commitments to maintain the claims in good standing. The analysis and interpretation of the results aimed at providing a better understanding of the structural geology and stratigraphy are still in progress and will continue in 2022. |
Source:
p. 8

The Halfmile Project is 100% held by Trevali Mining (Maritimes) Ltd., a 100% owned subsidiary of Trevali Mining Corporation.
Contractors
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Summary:
The Halfmile and Stratmat projectss are volcanic massive sulphide (VMS) deposits typical of the Bathurst Mining Camp (BMC). The BMC hosts 45 volcanic-sediment hosted massive sulphide deposits and 95 occurrences, including the world-class Brunswick 12 Mine. BMC deposits formed in a sediment-covered back-arc continental rift during periods when the basin was stratified with a lower anoxic water column. The basin was subsequently intensely deformed and metamorphosed during multiple collisional events related to east-dipping subduction of the basin.
The VMS deposits typically form lenses of polymetallic massive sulphide. Most deposits are zoned vertically and laterally from a high temperature, vent-proximal, copper-polonium bismuth-rich veined and brecciated core to vent-distal zinc-lead-silver-rich hydrothermal sediments. The vent complex is commonly underlain by a highly deformed sulphide stringer zone that extends hundreds of metres beneath deposits and consists of veins and impregnations of sulphides, silicates, and carbonates that cut chloritized and sericitized volcanic and sedimentary rocks.
The Halfmile project is underlain predominantly felsic volcanic rocks and lesser sedimentary rocks which are host to all massive sulphide deposits on the property. Provincial Government regional
mapping projects have classified the rocks as belonging to the Flat Landing Brook formation of the Middle Ordovician Tetagouche group and Nepisiguit Falls formation. ........

Mining Methods
- Mechanized Cut & Fill
- Post Pillar Cut & Fill
- Sub-level stoping
- Avoca
- Sub-level Retreat
- Longitudinal retreat
- Cemented backfill
Summary:
At Halfmile, all run-of-mine (RoM) material will be mined by underground mining method. Sublevel open stoping (SLOS) and Sublevel Retreat (SLR) will be the main mining methods planned, supplemented by post pillar cut and fill (PPCF) and mechanized cut and fill (MCF) mining for Upper zone where mineralization dip angle is approximately at 39 degrees. All mining methods will employ either cemented or unconsolidated waste rock as backfill. The mine plan includes 92% of RoM tonnes from SLOS/SLR with down holes (up holes for sill pillar recovery) on 20 m sublevels and cemented or unconsolidated waste rock fill, and 8% of RoM tonnes from PPCF/MCF with unconsolidated waste rock and cemented waste rock (sill level stopes only). There is no permanent sill or rib pillar considered for the SLOS/SLR mining. Limited sill pillars were planned only for the two trial mining opened mining fronts.
Access to the underground mine will be by an existing portal and ramp system developed previously to a depth of 170 m below surface. The ramp will be extended down to the mine bottom approximately 1,020 m below surface at a maximum gradient of -15% with dimensions of 5.0 m width by 5.0 m height, the same as the existing ramp.
Stope sequencing will generally be top-down block by block, and bottom-up within the mining block. On a mining level scale, both transverse primary-secondary stope sequence and longitudinal retreat mining will be employed, dependent on mineralization thickn ........

Source:

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Flow Sheet:
Summary:

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Combined production numbers are reported under
Halfmile-Stratmat Operation
Operational Metrics:
Metrics | |
Daily ore mining rate
| 2,600 t * |
Ore tonnes mined, LOM
| 9,376 kt * |
Tonnes milled, LOM
| 9,376 kt * |
Annual mining rate
| 910,000 t of ore * |
Mining scale, tpd
| 2,600 t |
* According to 2017 study.
Reserves at December 31, 2021:
Mineral Resource estimate is reported based on zinc equivalent cut off grade of 5% ZnEq.
Category | Tonnage | Commodity | Grade | Contained Metal |
Measured
|
0.4 Mt
|
Zinc
|
5.92 %
|
54 M lbs
|
Measured
|
0.4 Mt
|
Lead
|
1.99 %
|
18 M lbs
|
Measured
|
0.4 Mt
|
Copper
|
0.46 %
|
4 M lbs
|
Measured
|
0.4 Mt
|
Silver
|
40 g/t
|
520 koz
|
Measured
|
0.4 Mt
|
Gold
|
0.6 g/t
|
10 koz
|
Indicated
|
7.4 Mt
|
Zinc
|
7 %
|
1,146 M lbs
|
Indicated
|
7.4 Mt
|
Lead
|
2.37 %
|
389 M lbs
|
Indicated
|
7.4 Mt
|
Copper
|
0.16 %
|
26 M lbs
|
Indicated
|
7.4 Mt
|
Silver
|
35 g/t
|
8,450 koz
|
Indicated
|
7.4 Mt
|
Gold
|
0.29 g/t
|
70 koz
|
Measured & Indicated
|
7.8 Mt
|
Zinc
|
6.94 %
|
1,199 M lbs
|
Measured & Indicated
|
7.8 Mt
|
Lead
|
2.35 %
|
407 M lbs
|
Measured & Indicated
|
7.8 Mt
|
Copper
|
0.18 %
|
31 M lbs
|
Measured & Indicated
|
7.8 Mt
|
Silver
|
36 g/t
|
8,980 koz
|
Measured & Indicated
|
7.8 Mt
|
Gold
|
0.3 g/t
|
80 koz
|
Inferred
|
6.5 Mt
|
Zinc
|
5.62 %
|
806 M lbs
|
Inferred
|
6.5 Mt
|
Lead
|
1.51 %
|
216 M lbs
|
Inferred
|
6.5 Mt
|
Copper
|
0.15 %
|
21 M lbs
|
Inferred
|
6.5 Mt
|
Silver
|
23 g/t
|
4,720 koz
|
Inferred
|
6.5 Mt
|
Gold
|
0.1 g/t
|
20 koz
|
Operating Costs:
| Units | 2017 |
UG mining costs ($/t mined)
|
CAD
| 38.2 * |
* According to 2017 study.
2017 Study Costs and Valuation Metrics :
Metrics | Units | LOM Total |
Pre-Production capital costs
|
$M CAD
|
......
|
Sustaining CapEx
|
$M CAD
|
......
|
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