The mineralization of nickel, copper and cobalt within the VBI is magmatic sulphide genetically related to mafic magmatism. In deposits of this type, concentrations of sulphide result from the development of immersible sulphide-rich and silicate-rich liquids during the cooling of a magma. Chalcophile elements such as nickel and copper are preferentially partitioned into the sulphiderich liquid phase. Owing to differences in physical properties between these, such as differences in density and viscosity, they may spatially separate from each other to a greater or lesser extent.

Sulphide liquids are denser than silicate liquids and tend to concentrate at the base of mafic intrusions. Liquids of different density may also separate from each other through a process known as flow differentiation, which takes place where liquids pass through conduits or pass from one hydraulic regime (turbulent flow through a restricted passage, for example) to another (laminar flow in a larger magma chamber, for example). Complete separation of sulphide from silicate liquid by whatever process may result in the formation of a massive sulphide deposit with only minor amounts of entrained silicate; incomplete separation will result in the formation of disseminated sulphide deposits that can have extremely variable sulp hide:silicate ratios. Both types are commonly found in the same deposit.

The Ovoid and Mini-Ovoid deposits form an elongate, tadpole -shaped feature with a length of 800m along a west-northwest axis and a maximum width of 350m, narrowing to less than 50m at its northwestern end. The maximum vertical depth of the Ovoid deposit approaches 120m. A thin, initially north-dipping feeder dyke extends from the base of the Ovoid, but this dip reverses and eventually dips to the south.

The feeder dyke forms an incomplete marginal skin, 0-20m thick, of variably net-to leopard-textured mineralized troctolite and basal breccia with disseminated sulphides. This marginal skin surrounds a core of massive sulphide mineralization approximately 350m in diameter and up to 120m thick.

Toward the western extension of the Ovoid, the deposit becomes more elongate or trough-like in transition to the more dyke-like form of the Discovery Hill deposit. This area is known as the Mini-Ovoid deposit. The sequence of troctolite intrusion and sulphide deposit is more complete than in the Ovoid deposit. The upper or northern margin of the intrusion in this area consists of unmineralized gabbroic to troctolitic material, either in chilled contact with the overlying gneiss or as a breccia of intrusive and gneiss fragments. Sulphide content increases abruptly downwards into a zone of net- and leopard-textured troctolite with some massive sulphide veins and segregations. Sulphides within this unit are dominantly finer-grained, net-textured and have leopard textures. A large lens of massive sulphide, spatially distinct from the massive sulphide in the Ovoid deposit, occupies the central portion of the Mini-Ovoid deposit and overlies weakly mineralized basal breccia along the lower or southern contact.

The base of the Mini-Ovoid deposit merges into the feeder dyke, which dips about 70º to the north at this location.

In the southeast corner of the Ovoid deposit, mineralized troctolite and basal breccia extend over a buried ridge of footwall gneiss that separates the Ovoid deposit from the Eastern Deeps chamber. Immediately southeast of the Ovoid deposit, the troctolite broadens into the main troctolite intrusion called the Eastern Deeps chamber, host to the Eastern Deeps deposit. The area known as the Southeast Extension is the variably mineralized zone between the Ovoid deposit and the Eastern Deeps deposit. The Southeast Extension mineralization averages between 50m and 100m thick and subcrop at the southeast end of the Ovoid deposit, plunging eastward to a depth of 450m.

The Ovoid/Mini-Ovoid and Southeast Extension deposits are completely covered by 15-20m of unconsolidated glacial and marine sediments.

Nickel distribution in massive sulphide is remarkably consistent throughout the Ovoid and Mini-Ovoid deposits.

Copper grades are considerably more variable than those of nickel. Copper grades in massive sulphide are highest along the southwest side and central portions and lowest along the west, north and east sides of the Ovoid deposit.

Nickel distribution in massive sulphide is remarkably consistent throughout the Ovoid and Mini-Ovoid deposits.

The massive sulphide is composed of approximately 75 per cent pyrrhotite/troilite, 12 per cent pentlandite, 8 per cent chalcopyrite/cubanite and contains 5 per cent magnetite. The pyrrhotite is hexagonal and on average contains about 0.29 per cent nickel. The pyrrhotite to troilite ratio is about 70:30. The troilite contains only trace amounts of nickel.

The pentlandite is coarse grained and often forms coarse “loop textures” rimming large crystals of pyrrhotite. The pentlandite is frequently associated with magnetite, which is dispersed throughout the sulphide minerals. Magnetite can occur in local concentrations, ranging from less than 5 per cent to as high as 30 per cent.

The cubanite occurs as intergrowths with chalcopyrite as exsolution lamellae and rarely as granular aggregates within the chalcopyrite. The chalcopyrite to cubanite ratio averages about 90:10 but high concentrations of cubanite are locally present.

The Ovoid deposit is planned to be mined utilizing conventional open pit methods. VBNC intends to drill on 5m benches, with final walls being double (or quadruple) benched. Material is planned to be loaded into 50 tonne haul trucks using wheel loaders and ore is planned to be hauled to the primary crusher located at the mill. Waste rock and overburden is planned to be hauled and deposited on dumps located within close proximity to the pit. All waste material identified as potentially acid generating (“PAG”) will be hauled to Headwater Pond for underwater deposition.

Metallurgical process for the concentrate includes conventional crushing, wet grinding and differential flotation, using slaked lime for pH control throughout the circuit, to produce high-grade and middling nickel concentrates and a copper concentrate.

We mill Voisey’s Bay ore on site and ship it as an intermediate product (nickel concentrates) primarily to our Sudbury and Thompson operations for final processing (smelting and refining).

Annual production
• ~ 50,000 tonnes nickel-in-concentrate, containing 2,300 tonnes cobalt and up to 6,800 tonnes copper
• ~ 32,000 tonnes copper-in-concentrate.

In 2016, Long Harbour facility processed Voisey’s Bay high-grade nickel concentrates. In 2017, as a result of the continuing ramp-up of the Long Harbour nickel refinery, copper cathode and cobalt metal will be produced for the first time. The portion of mid-grade and high-grade concentrate not shipped to Long Harbour in 2017 will be shipped to our Sudbury and Thompson operations for final processing (smelting and refining) while copper concentrate will be sold to the market. Shipments of nickel concentrate to Sudbury and Thompson are expected to cease by the end of 2017. By the end of 2017, Vale plans on shipping all Voisey’s Bay nickel concentrate to Long Harbour refinery.

In 2017, as a result of the continuing ramp-up of the Long Harbour nickel refinery, copper cathode and cobalt metal will be produced for the first time.