Overview
Stage | Permitting |
Mine Type | Underground |
Commodities |
|
Mining Method |
|
Processing |
- Filter press plant
- Dewatering
- Flotation
|
Mine Life | 9.5 years (as of Jan 1, 2022) |
The Project sequentially develops the Tower deposit and Rail deposit, initially beginning with the Tower deposit. |
Latest News | Rockcliff Metals Files PEA Technical Report on SEDAR February 22, 2022 |
Source:
p. 15
Rockcliff Metals Corporation’s 100% owned Tower and Rail properties.
Deposit Type
- VMS
- Breccia pipe / Stockwork
Summary:
Deposit Types
At the Project, VMS sulphide mineralization that hosts both the Tower Deposit,and the Rail Deposit are consistent with the characteristics of VMS deposits.
The original depositional and stratigraphic relationships are obscured at the Tower Property by the lack of outcrop and the overprinting effects of high metamorphic grade and deformation. The Tower Deposit is interpreted to be a remobilized, high-grade VMS deposit. The Tower Deposit is the only known VMS deposit in the TNB. The Tower mineralization is similar to the VMS Cu-Zn-Ag-Au deposits in the Paleoproterozoic Kisseynew Domain and the Flin Flon-Snow Lake Belt (Bailes and Galley, 1999; Syme and Bailes,1993), to the west, thento the Ni sulphide deposits in the TNB. The closest known VMS deposit to the Tower Property is the Talbot Deposi twithin the Talbot Property, 35 km west of the Tower Property (Simard et al., 2010). The style of VMS mineralization at the Talbot Property appears to be very similar to the style of VMS mineralization at the Tower Property.
The closest known and well-characterized VMS style mineralization to the Rail Deposit are at the Lalor Lake and Chisel Mines located near Snow Lake, 38 km northeast of the Rail Deposit (Galley et al., 2007). The depositional environment for the Rail Deposit is interpreted similarly to that of the VMS deposits in the Flin Flon and Snow Lake mining camps. The Rail Deposit also shows evidence of regional metamorphic and deformation overprints.
Sulphide Mineralization
Tower Property
The Tower deposit mineralisation is associated within a sulphide-rich schist to breccia hosted within biotitemuscovite schist to the north and hornblende gneiss to the south ( Coueslan, 2018). The Tower deposit is approximately 1,000m long, 700m deep, and 1.92m wide. It strikes approximately 13° and dips 75-85°E and cuts the regional foliation. The mineralisation consists of rounded to subangular, mm- to cmscale fragments of wall rock with a matrix of semi-massive to massive sulphides. The sulphides are mainly chalcopyrite, pyrite, pyrrhotite, and sphalerite. The mineralisation is interpreted to be mobilized from its source and to form the matrix of a fault breccia in a late structure. Although Beaudry (2007) interprets the mineralisation to be post-deformational in origin, recent core from hole TP10-004 is obviously foliated and indicates that at least some of it is pre- or syn-deformational (Generic Geo, 2019). The biotite-muscovite schist is interpreted to represent an intense sericite altered zone in the footwall to the Tower deposit.
Rail Property
The Rail deposit consists of a single lens of massive and stringer sulphides. The sulphides are mainly pyrite, pyrrhotite, chalcopyrite, and sphalerite. From diamond core drilling, the deposit averages 1.6m in width, approximately 600m in depth, and has a strike length on surface of approximately 650m.
The Rail deposit VMS mineralisation is deformed, as indicated by the presence of Durchbewegung textures with milled sub-angular to rounded quartz and wall rock fragments within the massive sulphide lenses. Chalcopyrite occurs as stringers and fracture fillings and appears to have undergone varying degrees of remobilization. Approximately 140m west of the Rail deposit, an additional pyrrhotite-rich massive sulphide horizon was discovered (Private Report, HBED, 1998).
Summary:
At the Tower property, the mine will be accessed by a sinking box cut that will be driven at -10% to establish a large free face of 10m to 12m. The mine will be accessed from the surface by a decline collared in the rockface. The first two rounds of the decline will be designed to be upgrade at a sufficient grade to allow water to drain away from the portal. As the sinking cut is downgrade, a sump will be established outside the portal to control water and prevent inflows to the mine.
At the Rail property, the mine will be accessed from the surface by a decline collared in the hillside. An excavation will be cut into the hillside to create a large free face in which to collar the portal. The floor of the cut and the first two rounds of the decline will be designed to be upgrade at a sufficient grade to allow water to drain away from the portal.
The high value material at both projects sits in steeply dipping narrow veins, 1.5m to 2m wide, which is conducive to Alimak raise platform mining. Both declines will be driven at a nominal 15% downgrade and access the upper sections of the ore zones at approximate 100m intervals. Stoping blocks will be 100m to 125m high by 20m wide.
The mining method selected for both projects is the Alimak long hole stoping method. Main mining levels would be developed every 100m to 130m vertically. Each mining block would be set-up with a backfill system off the main backfill raise. Each stope would be 20m wide × 100m to 130m high. Drawpoints would be developed every 20m along the hanging wall drift, with Alimak nests opposite the drawpoint.
With the Alimak mining method, a pilot raise will be developed in the centre of a stope from the undercut to the level above. The raise would be screened over its entire length to facilitate drillers working in the raise and supported with 1.8m long resin grouted rebar on a 1.2m by 1.2m pattern and welded wire mesh screen (1.2m by 2.4m sheet with 5.6 mm wire thickness, 100 mm × 100 mm apertures) on the backs and 1.2m rebar and screen on the walls. Screen sheets will be installed with a 0.2m overlap.
The length of the stopes has been established using an allowable hydraulic radius (open stope area divided by perimeter) that depends on the rock quality and using an empirical design method. If the stopes were to remain open after mining, then sill pillars and rib pillars would be required to prevent the collapse of the hanging wall, but significant ore would be left unmined. To minimise pillars and prevent the possibility of ground failure, stopes will be backfilled.
Following development of the pilot raise, the Alimak would be left in the raise and a longhole ring drill installed on the work platform. The longhole drill would drill 64 mm horizontal drill holes (approximately 8.5m in length) parallel to the footwall and hanging wall of the potentially economic mineralisation. Drill holes would be loaded with ANFO and Nonel detonators and blasted in horizontal slices into the undercut below. Access to stope raises to allow workers to perform drilling and blasting functions on the Alimak would be from the level above the stope. Broken potentially economic mineralisation would be mucked from the undercut by LHDs and transported to the ore pass. The final 5% of the stope will require mucking by remote controlled LHDs.
The initial stope undercut sills would be developed to full width of the zone to be mined by 3.5m high. The openings would be drilled with 2 boom E/H jumbos and mucked with 3.0m3 bucket LHDs. Ground support would consist of 1.5m resin rebar and screen.
The Alimak pilot raises would be developed 3m × 2.4m using stopers and the walls of the raise supported by resin rebar and welded wire mesh screen.
Stope mucking would utilise 3.0m3 bucket LHDs mucking in the drawpoints.
The stopes would be mined in a primary/secondary sequence. Primary stopes would be those where all stope walls are in rock. Secondary stopes are those where the stope walls along strike in the ore consist of backfill.
Mined out stopes would be backfilled with cemented (primary stopes) and uncemented (secondary stopes) rockfill.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
Cone crusher
|
|
|
|
1
|
Ball mill
|
|
|
|
1
|
Regrind
|
|
|
|
2
|
Rod mill
|
|
|
|
1
|
Summary:
The ore will be processed in a two-stage crushing circuit feeding a screen. The screen oversize is sent back to the cone crusher for re-sizing. The screen undersize feeds a rod mill in the first stage of grinding. The second stage of grinding is a ball mill, which produces the final ground product with a P80 of 124 microns at Tower, 154 microns at Rail.
MILL DESIGN AND POTENTIAL ALTERNATIVE
One of the elements to the process design for the Project is the potential utilization of modular processing systems technology.
Designed to allow the rapid deployment of a complete mineral processing plant, Sepro Mobile Mill systems are ideal for smaller tonnage operations and mining operations with short mine life. Easily relocatable, the main process equipment is mounted on road transportable custom built trailer assemblies. These mineral processing plants require minimal site civil works. Mobile processing plants can be designed to encompass a wide variety of process options from crushing through to the final concentrate collection. Sepro.
Processing
- Filter press plant
- Dewatering
- Flotation
Flow Sheet:
Summary:
Testing of the two properties is completed to a scoping level. This testing indicates that the grind for rougher flotation can be as coarse as 150 µm. Ore sorting, though not considered in the current flow sheet, shows promise and may provide opportunities for reduced tonnages to the grinding circuit with acceptable losses in recovery.
The flow sheet considered for the purposes of this study is a modular design. This will allow for production at lower tonnages in the early stages of operation with increases possible by duplicating production modules.
A single module comprises a crushing line followed by two parallel flotation lines. For simplicity, the flow sheet shows a single flotation line. The de-watering streams, including the thickeners and pressure filters, are common in both lines. The capital cost is estimated based on a Sepro Mineral Systems Corp. modular design. The flow sheet includes recycle flows in the metal cleaning circuits. These flows have not ........

Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Copper
|
Head Grade, %
| 2.89 |
Copper
|
Concentrate Grade, %
| 31.3 |
Copper
|
Recovery Rate, %
| 97.2 |
Zinc
|
Head Grade, %
| 0.93 |
Zinc
|
Concentrate Grade, %
| 51.8 |
Zinc
|
Recovery Rate, %
| 74.2 |
Gold
|
Recovery Rate, %
| 63 |
Gold
|
Head Grade, g/t
| 0.81 |
Silver
|
Recovery Rate, %
| 63 |
Silver
|
Head Grade, g/t
| 12.6 |
Reserves at February 1, 2022:
The 1.5% CuEq cut-off.
Category | Tonnage | Commodity | Grade |
Indicated
|
3,764,000 t
|
Copper
|
2.51 %
|
Indicated
|
3,764,000 t
|
Zinc
|
0.79 %
|
Indicated
|
3,764,000 t
|
Gold
|
0.64 g/t
|
Indicated
|
3,764,000 t
|
Silver
|
10.82 g/t
|
Inferred
|
1,578,000 t
|
Copper
|
2.01 %
|
Inferred
|
1,578,000 t
|
Zinc
|
0.93 %
|
Inferred
|
1,578,000 t
|
Gold
|
0.67 g/t
|
Inferred
|
1,578,000 t
|
Silver
|
7.85 g/t
|
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