Voisey's Bay

Overview

Vale's Voisey's Bay operation in New foundland and Labrador is comprised of the Ovoid mine, an open-pit, and deposits with the potential for underground operations at a later stage. Vale mines nickel sulfide ore bodies, which also contain copper and cobalt. The mine is operating since 2005. Current mine life is approximately 30 years.

Vale mills Voisey Bay's ore on site and ships it as an intermediate product (nickel concentrates) primarily to its Sudbury and Thompson operations for final processing (smelting and refining), while copper concentrate produced is sold in the market.

A US$2.8 billion hydrometallurgical processing facility is being constructed at Long Harbour, Newfoundland that will use the nickel concentrate produced at Voisey's Bay and would produce a finished nickel concentrate. Construction work began in 2009.

The electricity requirements of Voisey Bay operations are supplied through diesel generators.

Location

Newfoundland and Labrador is the easternmost province of Canada. The province's capital and its largest city is St. John's.

Long Harbour is located about 95 kilometers south of St. John's.

Following the collapse of the cod fishery in early 1990s the economy was depressed for a number of years. Nowadays due to a major energy and resources boom the province's economy is flourishing. The service industry, the nickel and iron ore mining and the oil extraction industry are the economy's mainstays.  

Geology & Mineralization

The regional geology is dominated by juxtaposed Archean (Nain Province) and Proterozoic (Churchill) gneiss terranes which were intruded along the ca. 1800 Ma suture by suites of troctolitic, gabbroic/anorthositic and granitic plutonic rocks of the Nain Plutonic Suite (NPS). The Voisey's Bay Intrusion (VBI), Ashley Intrusion and Mushuau Intrusion of the NPS are dominantly composed of olivine gabbro and troctolite with variable amounts of leucotroctolite, melatroctolite, olivine norite, gabbronorite and ferrodiorite. The Voisey's Bay deposits are hosted by the VBI, which has been estimated to be at 1333 Ma old.

The VBI assimilated the Churchill gneiss in a series of sub-chambers below the present level of erosion and that led to a sulphide saturation of the magma. These magmatic sulphides accumulated in physical traps.

The original discovery was made in 1994 when a steep northerly dipping mafic body returned high nickel-cobalt-copper results from drill testing of massive pyrrhotite, pentlendite and chalcopyrite mineralization; the average thickness of the first 4 intersections was 41 m. 

There are four principal types of sulphide mineralization at Voisey's Bay: massive, leopard-textured, basal breccia, and disseminated in variable-textured troctolite.

The estimated mineral reserves and mineral resources at Voisey's Bay are contained within distinct deposits within the feeder dykes and at the junction of the feeder with a chamber (2003). Deposits that occur within the feeder include the Reid Brook, Discovery Hill and the Ovoid/Mini-Ovoid. The Eastern Deeps deposit occurs at the junction of a feeder dyke with the Eastern Deeps Chamber. The Ovoid and Mini-Ovoid deposits and a portion of the Southeast Extension deposit constitute the mineralization contained within the open pit.

The Voisey's Bay project includes four main deposits: (i) the Ovoid (being mined) and related deposits (including the Southeast Extension); (ii) the Eastern Deeps; (iii) the Reid Brook; and (iv) Discovery Hill. While the Ovoid and related deposits are accessible by open-pit mining, most of the mineralization discovered to date (2003) in the remaining deposits is not.

The Ovoid deposit, as well as what is referred to as the Mini-Ovoid deposit, and the near-surface portion of the Southeast Extension deposit are being mined. Mineralization in the Ovoid deposit is contained within troctolite and consists of a bowl-shaped accumulation of massive sulphide mantled by a marginal zone of disseminated sulphide hosted by inclusion-bearing troctolite breccias. The mineralogy is generally simple and consists of pyrrhotite-troilite intergrowths, pentlandite, chalcopyrite, magnetite and minor amounts of cubanite.

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.

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 Sara prospect is located 6 km north of the "Ovoid" and is characterized by narrow intersections of high grade nickel sulfides.

The "Red Dog" is a large area 2 km south of the Ovoid and contains significant thicknesses of sulphide mineralized variable troctolite.

As of December 2011, mineral reserves were estimated at 21.8 million tons gradingt 2.50% nickel, 1.39% copper and 0.12% cobalt.

Mining & Operation

Voisey's Bay mine, in Newfoundland and Labrador, is an open-pit mining operation with the potential for underground operations at a later stage. Vale mines nickel sulfide (magmatic) ore bodies, which also contain copper and cobalt.

In 2011, the Ovoid open pit mine produced 2.366 Mt ore grading 3.38% nickel and 2.39% copper.

Operations at the mine and concentrator at Voisey's Bay began in 2005. During operations, the mine and concentrator employ in average about 450 people.

Pending the results of an underground exploration program, development of an underground mine and expansion of the concentrator would begin around 2018. Vale estimate then an additional 350 people will be employed at the mine and concentrator, increasing total employment there to 800.

Processing

Processing is being done on site (crushing, grinding and flotation) and the resulting nickel concentrate is being shipped to Vale's Thompson for further processing - i.e. smelting and refining operations. There is a port facility at Edward's Cove in Anaktalak Bay that includes a dock, a concentrate storage building and equipment used to load concentrate on ships.

A portion of Voisey's Bay nickel concentrate is also toll-smelted and toll-refined by unrelated parties in Europe. The electricity requirements for Voisey's Bay mine are supplied through diesel generators.

Beyond 2013, the nickel concentrates will be shipped to Vale's hydrometallurgical plant being constructed at the Long Harbour site to produce finished nickel, while the copper concentrate will continue to be produced at Voisey’s Bay and sold in the market. Copper concentrate from Voisey’s Bay are sold under medium-term contracts to customers in Europe.

The electricity requirements are supplied through diesel generators. There are six diesel generators on-site, of which normally only four are in operation, producing 12 MW.

The processing facility at Long Harbour, Newfoundland will produce finished nickel products. It would cost US$2.8 billion and would employ 475 people.

Environment & Community

The Voisey’s Bay deposit is located within areas that are subject to land claims by Innu and Inuit. Rights to these traditional lands belong to two Aboriginal groups – the Innu and Inuit of Labrador who are represented by Innu Nation and the Nunatsiavut Government, respectively.

Vale has successfully negotiated Impacts and Benefits Agreements (IBAs) with Nunatsiavut Government and Innu Nation, resulting in a mutually beneficial relationship where benefits to Aboriginal people are maximized and negative outcomes are minimized. While details of the agreements are confidential, they do provide specific business, employment and training opportunities for
members of Innu Nation and Nunatsiavut Government related to the mine and concentrator component of the development.

Voisey's Bay is a fly-in/fly-out remote mining operation.

The hydrometallurgical process that is going to be employed at the new Long Harbour plant has a major environmental advantage over smelting because it does not produces harmful air emissions but mostly solids that are easy to be contained.