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The Goro Nickel Project located on the South Pacific island of New Caledonia commenced production in August 2010. The expected annual capacity of the project is 60,000t of nickel and 4,300t to 5,000t of cobalt.
Goro is considered among the world’s best-known laterite ore bodies, with 55 million tonnes of estimated measured and indicated mineral reserves. Goro was acquired by Brazilian iron ore and nickel giant CVRD in 2007 after its friendly $19bn takeover bid for Inco.
Vale (formerly Vale Inco) holds a 69% interest in the Goro project. Through a jointly owned company called Sumic Nickel Netherlands, Japan’s Sumitomo Metal Mining and Mitsui own 21%. The remaining 10% is held by the three provinces of New Caledonia.
The total cost of development was estimated at $3.2bn. Exploration of the site was first carried out in 1969. Production at the Goro nickel plant was halted in May 2014 following spillage of approximately 100,000 litres of effluent in a creek due to the solution transferring circuit misconfiguration.
Geology and reserves
The deposit on the Goro Plateau in New Caledonia is a classic deposit in its composition. It comprises iron oxides on the surface (laterites) and magnesium silicates beneath (saprolite).
The nickel and cobalt contained therein result from chemical concentrations within this residual formation.
Of the world’s laterite deposits, this has one of the highest nickel contents. Proven and likely reserves in the initial mining area of the Goro Plateau total 124 million tonnes, with an average nickel content of 1.48% and a cobalt content of 0.11%.
As well as reserves, around the initial mining area, there are indicated and measured resources estimated at 55 million tonnes, giving a nickel content of 1.49% and a cobalt content of 0.12% as of 2009.
The mine on the Goro plateau is opencast, dug to a depth of 50 to 60m. It was estimated that some four million tonnes of dry ore would be removed each year, with 12 million tonnes of earth shifted.
Initially, the superficial layers which have no commercial use are cleared away from the plateau area. The laterite and saprolite ore is extracted from a series of terraces using hydraulic excavators and bulldozers. Haulage is being undertaken by a fleet of dumper trucks.
The deposit is a single, continuous but thick layer, therefore several faces will be opened laterally and vertically so that the entire profile can be extracted from the surface lateritic layer and the saprolite which is further down.
The mine has been given a life of 29 years, during which time mining pits will be filled and replanted at the end of each mining cycle until 2041.
AECOM provided port planning and engineering support services for the project.
Vale boasts that its mining processes involve state-of-the-art, fourth-generation hydrometallurgical techniques, designed to make it possible to profitably process laterites with low nickel content at low cost, whilst reducing the impact on the environment.
The mined ore is screened and ground and then mixed with water to create a combined pulp of limonite and saprolite. Rigorous control of chemical quality and particle size is undertaken.
The pulp is then conveyed via a pipe which extends for 8km to the autoclave at the processing plant. When it is in full production, the plant will process approximately 536t of pulp per hour.
Production and costs
At full capacity, Goro will produce 60,000t annually of nickel in the form of nickel oxide, which will contain 70% to 80% nickel. Between 4,600 and 5,500t of cobalt will be produced each year.
Details about exact production costs are scant. However, Vale has repeatedly stated in official documents that the mine is on track to being one of the world’s more efficient operations.
Vale is planning a second phase for Goro for the next decade, so there is a huge financial commitment riding on project completion and in reaching an accord with project opponents.
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