SLN: a long-standing player in nickel

Founded in 1880 by the Frenchman Jules Garnier and the Briton John Higginson in Nouméa, New Caledonia, Société Le Nickel (SLN) became a wholly-owned subsidiary of a new parent company called Eramet-SLN in 1985, now the Eramet group. It is the world number one producer of ferronickel, a product intended for the stainless steel market.

From stainless steel to special steels, alloys and superalloys, nickel is omnipresent and is found in the basic industries, construction, transport, electric batteries and coins. Its rich and varied properties also provide it with other lower-volume avenues such as electroplating, which involves placing a thin deposit onto plumbing and automotive parts by electrochemistry.

SLN's activities are spread across mining centers and a metallurgical plant:

  • Thio (New Caledonia, east coast): this is SLN's long-standing mining site, which opened in 1880
  • Kouaoua (New Caledonia, east coast): this mining site was the world's largest deposit of silicate ore
  • Népoui-Kopéto and Tiébaghi (New Caledonia, west coast): in addition to their mine, these two sites also have enrichment plants
  • Poum (New Caledonia, northern end): a booming mining site set for major growth
  • Doniambo (New Caledonia, west coast): SLN's metallurgical plant, with its high-grade ferronickel production unit. Its location nearby the port of Nouméa gives the plant direct access to ore carriers and cargo vessels.

An integrated value chain

From the mine…

Société Le Nickel-SLN's ore deposits are mined using open-pit methods. They are usually located at an altitude of between 500 and 1,000 meters. Deposits are defined by geological, geochemical and geophysical studies, and the geological structures are modeled. Extraction is guided by mining planning geology and carried out using excavators. Since 1975, SLN's mining techniques have been devised to protect the environment, including storing waste rock in waste rock piles, water management, revegetation, etc.

…to processing

The ore is then transported by trucks with a load limit of 50 to 100 tons, depending on the mine. In Népoui, it is carried to the enrichment plant via a 7 km hydraulic pipe, which allows a larger portion of the deposit to be exploited (by including lower-grade ore), thereby increasing the lifespan of reserves. A similar procedure (UTM) was adapted to process ore from the Tiébaghi mine, which was unveiled in November 2008.

…and transformation

The Doniambo plant is one of the world's two largest ferronickel production units and has its own power plant. The ore is homogenized, dried, burned and then melted in electric furnaces. The resulting product is transformed into directly sellable ferronickel, SLN 25 (with a content of 22% to 27% nickel), which is found in stainless steels.

The Havre-Sandouville refinery uses a hydrometallurgical process specially developed by Eramet's research teams. The nickel matte (which contains 75% nickel) is ground, then dissolved using chlorine. Several successive extraction stages are conducted to extract the iron (in the form of sellable iron chloride) and cobalt (in the form of sellable cobalt chloride). After purification, the pure nickel chloride solution obtained can be sold as is (liquid nickel chloride), in the form of nickel salts (nickel carbonate, nickel chloride hexahydrate or anhydrous) or processed to obtain a very pure nickel cathode (over 99.97% nickel content).

Key figures

  • 1880 : création de la SLN
  • 1985: foundation of Eramet-SLN
  • World number 10 producer of nickel
  • World number 1 producer of ferronickel (used in stainless steel)
  • 54,250 tons produced in 2018