The Scully Deposit mineralization style is a deposit typical of the Superior-Lake type of Iron Formations.

The Scully Mine lies within the Labrador Trough in Western Labrador. The Sokoman Formation is an iron formation that consists of three iron bearing formations, named the Upper, Middle and Lower Iron Formations. The Sokoman Formation is more than 300 m thick near the Scully Mine and has been subjected to two episodes of folding and metamorphism during the Hudsonian and Greenville orogenies, resulting in a complex structural pattern in the Wabush Area. The younger Menihek and Shabagamo Formations and the older Denault, Attikamagen, and Wishart Formations all outcrop in the vicinity of the mine site. The mineral deposit that defines the Scully Mine consists of folded and faulted stratigraphic beds of iron-bearing units within the regional Sokoman Iron Formation.

The ore minerals are hematite (specularite), magnetite, and martite. The waste minerals are quartz and hydrated iron oxides such as limonite and goethite. Manganese oxides also occur in bands or are disseminated throughout the iron-bearing units.

The Scully Deposit can be divided into two distinct structural areas. Bounded to the east by the Wabush Lake lies a series of northwest- trending folds. This trend continues as far west as the west end of Knoll Lake, where the folds transition to an east-west trend.

The interpretation by O’Leary (1972) explains a series of simple folds in the east plunging gently to the southeast and cut by an almost vertical fault zone, 75 meters wide, which is believed to be barren of ore minerals. The area to the west is described as a succession of a synform, an antiform and a second synform to the south. The axes plunge east in the eastern part of the fold system, and west in the western part.

The most prominent structural feature in the East Pit, geologically, and as far as mining considerations are concerned, is a reversed fault which runs approximately in a northwest direction through the orebody. This fault dips steeply to the east, with the basement rocks thrown up some 75 meters on the western side. The fault is marked by a series of clay seams, varying in color from pink to a light cream. In addition, the fault is characterized by elevated level of manganese, giving assays as high as 6 or 7 percent. The sooty black appearance of the ore against the lighter clay provides a striking contrast and the fault can be traced quite easily along strike as mining advances. A number of small parallel fault zones have been traced.

The operation consists of a conventional surface mining method using an owner mining approach with electric and diesel hydraulic shovels and mine trucks. Some major mine equipment required for the restart of the project, such as drills and hydraulic shovels, are present on site as this equipment was acquired early on in 2017. The study consists of resizing the open pit based on parameters outlined in this study and producing a life-of-mine (“LOM”) plan to fill the mill to capacity subject to constraints with a mining rate of 35 Mtpy.

Drill and blast specifications are established to effectively single pass drill and blast a 12 m bench. For this bench height a 349 mm blast hole size is proposed with a 6.5 m burden by 7.5 m spacing with 1.5 m of subdrill in ore. The blast pattern in waste is identical with adjusted explosive column height. These drill parameters, combined with a high energy bulk emulsion with a density of 1.2 kg/m3 , result in a powder factor of 0.50 kg/t for ore and 0.45 kg/t for waste. Blast holes are initiated with electronic detonators and primed with 450 g boosters. The bulk emulsion product is a gas-sensitized pumped emulsion blend specifically designed for use in wet blasting applications.

The majority of the loading in the pit will be done by two hydraulic shovels equipped with a 24 m3 bucket. The shovels are matched with a fleet of 211 metric tonnes payload mine trucks. The project already owns two 24 m3 hydraulic front shovels (one electric and one diesel) and one 17m3 diesel front shovel. The hydraulic shovels will be complemented by one production front-end wheel loader with a 12 m3 bucket. The truck fleet reaches a maximum of 16 units excluding equipment replacement.

Mining of the Scully Mine is planned with seven pit sectors referred to as Boot Pit, West Pit Extension North, West Pit Extension South, West Pit, South Pit, East Pit West and East Pit East. Mining has taken place in all of these pit sectors except for Boot Pit which was in the Cliffs LOM plan where only initial efforts to strip overburden and prepare production benches had been undertaken.

The pit area measures approximately 5.4 km in an east-west direction and is approximately 2.1 km northsouth in relation to the South Pit. The final pit contains 443.7 Mt of ore at an average grade of 34.83% Fe, 2.58% Mn and 5.43% SAT. This Mineral Reserve is sufficient for a 26 year mine life with possibilities for expansion at higher iron ore prices and the conversion of Inferred Mineral Resources to Measured and Indicated Mineral Resources. A total of 831.4 Mt is to be mined for an overall strip ratio of 0.87:1.

The inter-ramp angles vary from 46 to 32.0 degrees based on a final 12 to 24m bench height. The third domain recommendation varies with the dip of the ore body, rangin from 35.2 to 52deg IRA. The pit slope profile has a geotechnical catch bench every 120 m of vertical stack height. This geotechnical catch bench mitigates risks from overbank hazards on the pit wall. Overbank hazards result from muck that spills down the slope of the previous pit phase filling the catch benches. The design allows the catch bench to be accessed to remove debris.

A total of 388 Mt of waste material is mined throughout the life of mine. At least 230 Mt has to be stored in waste dumps outside the pits. Waste rock storage is planned in depleted pits and in conventional waste storage area (dumps) outside of pits. In the early years of the project, waste material will be stored to the south of the pits, on waste dumps South and South West and inside the West Extension in-pit dump. Later, as the project expands to the East, the North Dump becomes active. Once the East Pit West is depleted, waste material is stored in this pit allowing for lower haulage costs and a reduced environmental impact. The North West dump is used for waste rock coming from West Pit extension North and Boot Pit in the later years of the project.

Ore stockpiles are located close to the crusher location (to the East). The stockpile location has an approximate 11.0 Mt capacity. Stockpiling exceeds 11.0 Mt towards the middle of the mine life to help feeding the mill while complying to the different constraints.

Crushing and Ore Handling
The ore will be hauled by 240 short tonne mine trucks. The trucks will discharge into two 54” x 74” primary gyratory crushers each driven by a 335 kW (450 HP) motor, at a nominal feed rate of 2,150 tph. Each crusher has a capacity of 3861 tph so only one is required to operate. The ore will be crushed at minus 8’’ (203 mm) and will be transferred by two 60’’ belt conveyors to bins ahead of the grinding circuit. Two new hydraulic hammers (one for each crusher) will break down any oversize rocks in the crusher cavity.

The capacity of the crushing circuit is limited at 3200 tph by the transfer conveyors. The crude ore storage bins have to be kept full at all time. There is an excess of 1000 tph compared to the mills throughput to build the storage in the event of feed interruption.

A belt magnet system will be installed to remove the tramp metal and avoid stopping the transfer conveyers for metal removal on the belt.

The primary gyratory crusher auxiliaries will include a crusher lubrication unit (including oil heaters and oil cooling fans), a spare main shaft and a complete set of relining platforms and liners removal pans. To facilitate maintenance and operation, the crusher area is serviced by an overhead crane.

Grinding
From the 22 000 metric tonne capacity crude ore storage bin, the ore is fed by vibratory feeders onto the mill feed conveyors. Each feeds one of the six fully autogenous mills at a rate up to 400 mt per hour per mill. The dimension of each mill is 24 feet in diameter and 8 feet long.

Mills discharge through a trommel screen where the screen undersize is fed into a wet vibrating screen with 1 mm width poly slots. Screen undersize is pumped to the spirals and screen oversize is pumped back into the mills. To reduce downtime, the recirculation pumps lining will be replaced.

The grinding process is wet, fully autogenous and requires no mechanical or chemical additives. To increase the availability of the grinding circuit, all the Mill gear will be replaced (Mills 1 to 5 were completed prior to the plant closure – Mill 6 will be done prior to restart). Secondly, for 5 of the 6 lines (line 4 already completed) the mill feed chute and feed conveyor will be modified to improve material flow and reduce the water addition that was required to avoid chute plugging.

For the first two full production years (Yr1 to Yr2) the plant theoretical capacity is established at 5.8 Mtpy of concentrate with ore processing rate of 2150 tph and plant availability at 89%. In reality, because of ramp-up activities the total production for Yr1 and Yr2 equals 10.1Mt. The plant has been sized to meet the general design criteria and parameters for the first two years at a rate of 5.8 Mtpy of concentrate. For Yr3 onward, the capacity increases to 6.1 Mtpy with ore processing rate of 2200 tph and plant availability at 92%.

Wet Concentration and Tails Thickener
The first stage of the concentration circuit is the rougher spirals. A total of 960 spirals (160 for each line), supplied by Mineral Technologies were installed in 1998. Spiral tails are pumped to a cyclone where the underflow is pumped to the tailings basin. The overflow is thickened in a 280 ft diameter thickener using flocculent to 35% solids (as original operation) before being pumped to the ........