The Hope Bay Property is located within the Hope Bay volcanic belt which is part of a massive structural-geological complex called the Slave Structural Province.

The Hope Bay deposits (Doris, Madrid, and Boston), as well as a large number of other prospects, are considered to be typical of orogenic-type mesothermal lode gold deposits, greenstone-hosted quartz carbonate vein deposits.

• The Doris gold deposit is a typical Archean lode deposit which occurs within an over 3 km long, steeply dipping quartz vein system, in folded and metamorphosed pillow basaltic rocks.
• The Madrid deposit area lies within a north-south striking package of mafic volcanic rocks, comprising a sequence of Fe-Ti tholeiitics, Mg tholeiitics, komatiitic basaltic, synvolcanic to late gabbroic, and ultramafic rocks.
• The geology in the area of the Boston deposit is a bimodal assemblage of mafic and felsic volcanic rocks in contact with sedimentary rocks, all of which are complexly folded about a large-scale synformal-anticline. The core of the anticline is occupied by mafic volcanic rocks that host the Boston deposit and these are in turn overlain by sedimentary rocks.

THE DORIS AREA
The Doris Deposit is located at the north end of the north-south trending Hope Bay greenstone belt of Archean age near Cambridge Bay in Nunavut. Gold mineralization is contained within predominantly sub vertical quartz veins hosted within mafic volcanic rocks.

The Doris Vein system is characterized by a series of north–south striking, sub vertical, goldbearing, brittle-ductile structures that commonly host wide, stylolitic, ribboned, or bull quartz veins.

Within the veins, gold is commonly associated with narrow tourmaline chlorite septa oriented parallel to and along the vein margins. Veins are not consistently mineralized along strike. Gold is distributed throughout vein structure but is usually concentrated near the footwall side of the vein, where visible gold is relatively common. Gold mineralization includes visible and disseminated gold occurring primarily with quartz veins ranging from a few centimetres to approximately 10 m in scale. Visible gold includes coarse leafy free milling grains located along vein margins, tourmaline septa, and wallrock fragments which are commonly associated with pyrite. Gold is also associated with disseminated sulphides at the margins of the quartz veins, or with sulphide clusters within the vein. Occasionally, gold is present within brecciated zones adjacent to the quartz veins. Sulphide mineralization consists of trace to 2% pyrite, trace chalcopyrite, rare sphalerite, and pyrrhotite.

THE MADRID AREA
The Madrid deposit area is located in the northern area of the Hope Bay volcanic belt, south of the Doris deposit. It includes the Wolverine-Madrid corridor which is defined as the belt of rocks extending from the southern end of Wolverine Lake to the northwest end of Patch Lake (Sherlock et al., 2002).

The Madrid deposit area includes the Naartok East, Naartok West, Rand, Spur, Suluk, Wolverine and Patch 14 deposits. The Madrid trend also includes the Suluk T3, and Patch 7 prospects.

The style of mineralization at Madrid is different from the Doris or Boston deposits and can be generally characterized by sulphidation and replacement of favourable stratigraphic units. The most favorable lithologies are Fe-rich tholeiitic mafic volcanics which have been extensively brecciated. Hydrothermal alteration at Madrid is characterized by an early assemblage of sericite micas and carbonate alteration, consisting of magnesite and ankerite with quartz-carbonate stockwork veinlets. The main gold-bearing alteration assemblage consists of secondary albite and paragonite with lesser carbonate as ankerite and quartz-ankerite stockwork veinlets. The higher gold tenor is associated with over 10% fine grained pyrite, intense albite flooding and hematite discoloration (Sherlock et al., 2012).

The gold mineralization within Naartok West, Naartok East, Rand, Suluk, and Patch 7 consists of quartz-carbonate stockwork veining, which overprints dolomite-sericite-albite-pyrite altered mafic volcanic rocks of the Patch Group. The gold mineralization is characterized by multi-stage brecciation and alteration with at least two separate gold mineralization events. Gold occurs within north-northeast, east, southeast, and north-northwest trending brecciated and carbonate altered zones and is associated with disseminated pyrite which has replaced brecciated mafic fragments

THE BOSTON AREA
Boston mineralization has been subdivided into the B2, B3, B4, and B5 zones.

The strongest mineralization in the Boston deposit is found within the B2 zone, particularly the section investigated by the underground workings. The B2 zone has been intersected to a depth of 1,000 m, with the highest grades located in the central part of the zone.

Compared with the B2 zone, mineralization in the B3 zone is less continuous and lower grade. The B4 and B5 zones are the smallest of the three main Boston ore zones. The B4 zone is a relatively small zone hosted on the eastern contact of the volcanic core, while the B5 zone comprises several mineralized horizons located south of the Newton Deformation Zone.

Fingas (2018) recognizes at least 6 styles of mineralization in the Boston deposit, which include: vein stringer sets hosted in transition breccia; discrete veins at geological contacts; fault-hosted veins; shear-hosted mineralization; vein domains at picrite contacts; internal picrite-hosted mineralization.

Vein stringer sets hosted in transition breccia is the most important mineralization style in the B2 zone and has been exposed in underground drifts. Mineralization consists of sulphide-bearing quartz-carbonate veins, typically hosted in both volcanic- and sediment-dominated transition breccia. Zones are typically planar, from 2 to 10 metre wide, with ore shoots plunging steeply to the southwest (e.g. ore shoots within the B2 zone with an apparent plunge of 77° to 225°).

Of the 16.8 Mt of ore produced during the LOM (2020-2034), the distribution by mine will include Doris at 7%, Naartok at 46%, Suluk at 22%, Madrid South at 5%, and Boston at 20%.

Current ore mining is ongoing at the Doris deposit and a small crown pillar recovery surface operation at the Madrid North deposit and advances to the Madrid North underground operation, Madrid South, Suluk and Boston deposits will occur sequentially over the defined Life of Mine (LOM).

Production for the Doris Plant LOM period (2020-2023) is on average 1,963 t/d from two mines including Doris and Madrid North (Naartok).

Production for the Madrid Plant LOM period (2024-2034) is up to 4,000 t/d from three mines including the Madrid North (Naartok, Suluk, Rand zones) the Madrid South (Patch 14 and Wolverine zones) and Boston.

Mining at the Hope Bay Project incorporates longhole mining methods in order to address the deposit geometry and anticipated ground conditions. Mining will take place under permafrost conditions where the mineralization is located away from any water bodies and under nonpermafrost conditions in what is known as the talik in the vicinity and under the lakes in the area.

Doris North will be under permafrost while the Connector and Central zones at Doris will be beneath the lake. A portion of the Madrid North deposit (part of Naartok) as well as the Madrid South deposits (Patch and Wolverine) are situated beneath the lakes and therefore will not be under permafrost conditions.

The deposits will be accessed, and services will be provided by a decline from surface with an average grade of 13%. The ramp will also be used for ore and waste haulage from the underground operations.

The Doris deposit is currently in production, with an existing ramp decline reaching active mining areas. Mining will continue as per current methods until depletion. Transverse and longitudinal longhole mining is planned for Doris. Madrid North (Naartok and Suluk) and Boston will be mined using longhole stoping methods with sub-levels placed at 20-m vertical intervals (16-m drilling heights). Both longitudinal and transverse accesses are used, depending on width of the ore zones. The Madrid South (Patch and Wolverine), where ore zones are much narrower, will be mined using longhole stope method with sub-levels placed at 16-m intervals (12-m drilling heights). The majority of stopes in Madrid South will have longitudinal accesses.

Sill pillars are placed throughout the deposit to improve the mining sequence by providing additional stoping fronts. Sill pillars will be recovered at the end of the sequence using up-holes.

Stopes will be backfilled using a combination of CRF and unconsolidated rockfill (UCF). The CRF will generally contain 5% binder, except 10% in sill pillars. The CRF will be mixed on surface and trucked to the stopes.

MINING METHOD
Sub-level longhole mining is forecast in all mining areas, with a combination of longitudinal and transverse stopes, depending on stope width. The use of Transverse Longhole mining was considered initially in the PEA study for the Madrid North Naartok zone, however, a review indicated that the large widths are made up of several veins with sufficient separation between them to allow a combination of Longitudinal and Transverse Longhole mining. Primary-secondary sequences are used in transverse stopes. Longitudinal stopes are planned with a retreat sequence towards a centre access.

The sub-level intervals were fixed at 20 meters for all the deposits except Patch and Wolverine where the interval is 16 meters to provide the required control for narrow lens of ore and the small diameter longholes that will be used. The nature of the veins did not appear conducive to the use of increased sub-level intervals and larger borehole diameters. The sub-level retreat (SLR) or longitudinal stoping method will be in use at all of the deposits. Stopes will be filled with a combination of CRF and unconsolidated rockfill.

The undercut drift and overcut drift are driven on ore and mining would start from the lower access retreating out towards the main access drift. Nominal stope strike lengths are 15 meters but will vary based on local geometry. Once a stope block is finished, CRF is introduced from the upper sub-level. CRF will be used until the fill covers all walls to be exposed with future mining; unconsolidated fill will be used for the remainder of the void.

Slot raises are drilled between three and four m from the previous stope to create the primary void. Most stopes will be drilled from the overcut downwards to the undercut. Upholes will be drilled to recover the level below the sill pillar, where a small “skin” will be left to prevent dilution of CRF.

Stope strike lengths are limited controlled in order to respect the HR values and prevent excessive dilution. This stoping system is advantageous by reducing waste development requirements but requires multiple active stoping sequences to maintain the planned production rate. Sill pillars are placed throughout the mine to divide the stope sequences.

The recommended drills are capable of drilling diameters from 50 to 89 mm in diameter. Drill holes of 63 mm are recommended for smaller stopes, combined with a tightly-space “dice-five” drill pattern. Larger diameter holes will be used in larger stopes with greater burden and spacing. Drill holes will be approximately 17m in length for most deposits, but 12 m at Madrid South.

Multiple veins are present in certain areas of the deposit. In some cases, spacing between the veins are sufficient to allow mining of each vein separately to minimize dilution. In some areas, particularly in Naartok and Suluk, the geometry is such that transverse stoping is more efficient. A primary stope sequence will be established in these areas, with secondary stopes later extracted.

Ammonium Nitrate/Fuel Oil (ANFO) is expected to be the primary blasting agent for both development and production, with standard Handidet detonators used for initiation.

DORIS PLANT (the currently operating processing facility)
Primary crushing
ROM material is hauled by trucks to the ROM pad to designated high-grade, intermediate, and low-grade stockpiles adjacent to the primary crusher area.

A vibratory grizzly feeder scalps out minus 80 mm ore via a fines feed chute, and feeds the oversize into the primary jaw crusher, a Metso Nordberg C100, with a product that is 95% passing (P95) 125 mm. The vibrating grizzly undersize and crusher discharge are conveyed by the primary crusher discharge conveyor (CV), under a self-cleaning belt-type tramp metal magnet t to the stockpile.

Crushed ore is reclaimed to feed each concentrating line, CL1 North and CL2 South, via separate reclaim tunnels for each train using two reclaim tunnel apron feeders, discharging onto two plant feed conveyors. The secondary and tertiary crushing circuits are low profile, modular construction supplied by Gekko systems, known commercially as the Python crushing trains. Both North and the South concentrating lines are nearly identical.

Secondary and tertiary crushing
The plant feed conveyor discharges to the secondary crusher feed conveyor and onto a vibrating grizzly feeder. The vibrating grizzly removes minus 50 mm material and the secondary jaw crusher, Metso model C80 crushes the oversize to a P95 of 50 mm.

The secondary crusher discharge reports to a vibrating feeder that combines the crusher product with the grizzly undersize, and the blended feed is then to the secondary dry horizontal screen, 1.2 m x 2.45 m, for sizing at 40 mm. The oversize is returned to the secondary jaw crusher for further crushing. A fixed-type magnet has been installed the head end of screen feed conveyor, along with metal detection. The undersize product is transferred to the wet tertiary screen.

The tertiary screen is fitted with panels having a 4 mm aperture by 25 mm long. The oversize from tertiary screen, is conveyed to one of the duty/standby tertiary crushers, Remco model 1530 vertical shaft impactor (VSI-type), 260 kW, for further size reduction.

Primary grinding
The primary milling circuit grinds ore to a target of P80 of 150 µm for flotation. The primary ball mill operates in closed circuit with the primary cyclones, with the overflow reporting onto the continuous gravity concentrator and the flotation circuit. Like the crushing circuit, the grinding and gravity concentration circuits are duplicated.

The primary mill is a frame-mounted overflow-type Outotec model 15-04 which is 2.7 m in diameter and has a 4.88 m long effective grinding length (EGL). The mill is installed with a 450 kW variable voltage variable frequency (VVVF) drive.

NEW MADRID PROCESS PLANT
Crushing, screening, and crushed ore storage
Run of Mine (ROM) material from the mine is trucked to the ROM pad. A front-end loader recovers the ore from the ROM pad and tips onto the Primary Grizzly to scalp out +600 mm material. The oversized +600 mm material is presented to the Rock Breaker to be broken and stockpiled for reclaim, while the -600 mm material flows via gravity into the dump hopper which has a capacity of 100 t. The dump hopper discharges onto an apron feeder followed by a vibrating grizzly feeder.

The vibrating grizzly scalps out minus 75 mm ore and feeds the oversize into the primary jaw crusher to be crushed to P95 125 mm. The vibrating grizzly undersize and crusher discharge are conveyed by the primary crusher discharge conveyor under a belt magnet to the surge bin feed conveyor and transferred to the surge bin. A metal detector is installed on the surge bin feed conveyor. A weightometer is installed on the crushed ore bind feed conveyor for primary crushing circuit control.

Crushed ore from the surge bin is metered using two apron feeders discharging onto the SAG mill feed conveyor. A weightometer is installed on the plant feed conveyor for feed rate control.

Grinding and gravity concentration
The grinding line consists of a single variable speed semi-autogenous grinding (SAG) mill, followed by a single ball mill operating in closed circuit with a cyclone cluster. The product from the grinding circuit (cyclone overflow) has a typical P80 of 150 µm. SAG mill discharge flows onto a vibrating screen to remove +12 mm pebbles. Screen oversize is transported by conveyor to the pebble crusher (cone crusher). Crushed pebbles are recycled to the SAG mill feed conveyor.

The SAG mill feed conveyor discharges ore, along with pebble recycle and grinding media, into the feed chute of the SAG mill together with mill feed dilution water. The SAG mill is fitted with discharge grates to retain grinding media and larger pebbles while allowing smaller particles to discharge from the mill. SAG mill grinding media is also added to the SAG mill feed chute with a 1 t kibble with a false bottom.

The SAG mill discharge screen undersize gravitates to the primary cyclone feed hopper where it is combined with the discharge from the ball mill. The slurry is transported to a single cyclone cluster using two variable-speed cyclone feed pumps (duty and stand-by).

Dilution process water is added to the cyclone feed hopper before the slurry is pumped to cyclone cluster for classification. Coarse particles report to the cyclone underflow and are directed to the ball mill feed chute via a boil box. The cyclone overflow stream gravitates to the vibrating trash screen via a cross-stream sampler.

A SAG mill feed chute removal system and a ball mill feed chute removal system are used to service the mills. A mill liner handler for each mill is provided.

The gravity circuit is fed from a dedicated pump on the cyclone feed pumpbox, with all tails and oversize stream recollected and pumped back to the ball mill feed. The screen undersize is fed to a centrifugal gravity concentrator. A batch of concentrate is produced every 45 minutes and fed to the intensive cyanidation unit (ICU) holding tank. The gravity tails are gravity fed back to the cyclone feed pumpbox by gravity.

Gravity concentrate will be fed to the ICU cone. Process water will be fed to the cone for approximately 30 minutes to deslime the contents. The ICU solution tank contains of a mixture made of sodium hydroxide, sodium cyanide, leach aid and fresh water. The reagent mixture is pumped through the bottom of the ICU cone producing a fluidized bed. Overflow returns to the solution tank.

The solution pumping cycle is continued for 16 hours to leach the gold into the solution. At the end of the cycle any remaining solution in the cone is pumped to the solution tank. The solids are rinsed with fresh water. The rinse solution reports to the solution tank. The pregnant leach solution is pumped to the gold room for electrowinning and refining. The barren solids are pumped back to the cyclone feed pumpbox.

The gravity concentration circuit will be installed after commissioning using equipment relocated from the Doris Mill.

Production for the Doris Plant LOM period (2020-2023) is on average 1,963 t/d from two mines including Doris and Madrid North (Naartok).

Production for the Madrid Plant LOM period (2024-2034) is up to 4,000 t/d from three mines including the Madrid North (Naartok, Suluk, Rand zones) the Madrid South (Patch 14 and Wolverine zones) and Boston.

DORIS PLANT (the currently operating processing facility)
The following is a summary of the proposed Doris Plant operation from 2020 to 2023. Ore will be sourced from the Doris and Madrid North (Naartok) deposits. The annual tonnage of ore processed is expected to be up to 730,000 t/a.

The plant recovers gold from the ore using a combination of gravity concentration and flotation. Flotation tailings, devoid of sulphides are sent to the TIA at a relatively coarse grind of 80% passing (P80) 150 µm. Gravity concentrates recovered by batch continuous centrifugal concentration are treated by intensive cyanidation ........