Doniambo nickel smelting plant - November 2000
Metallurgical production
The first nickel smelter was built in 1877 at "Pointe Chaleix", Noumea.
Currently, the SLN Doniambo smelting plant in Nouméa has an output of about 60 000 tonnes of nickel per year through electrical smelting. Nickel metal produced is contained in "ferronickels" for about 4/5 of the output, and in nickel mattes (nickel sulfide) for the balance. SLN was incorporated in 1880!
Ores exports
Nickel ores are exported by the so called "petit mineurs" (small miners). About 3 million tonnes of garnieritic ore (saprolite) are sold to Japan each year. They contain from 40 000 à 50 000 t of nickel metal. Since 1988 nickeliferous limonite is mined and exported to Australia. Yearly exports are about 2 Mt containing some 20 000 t of nickel and 2500 t of cobalt.
Valorisation
In metallurgical products nickel is valorised nearly four times the value of nickel in exported ores.
In 1999, metals (nickel et cobalt) tonnage exported in ores is identical to the tonnage of nickel metal sold in metallurgical products, 57 000 t in each case thus 114 000 t overall.
Value of exported metallurgical products was 31 billion Francs CFP (260 M€) against 8 billion CFP (67 M€) for the exported ores.
Two metallurgical technologies for lateritic nickel ores
According to the ores nature there are two different technologies.
Garnierite (saprolite) is processed by smelting in electric furnaces. This is pyrometallurgy ( SLN Doniambo plant).
Laterite (limonite) is processed by chemical agents (sulfuric acid or ammoniac) which dissolve nickel and cobalt from the ore. This is hydrometallurgy.
Projects to built one and even two new metallurgical plants are underway.
One of them located in the South at Goro, will produce nickel and cobalt from limonite. Construction started in 2002. It was halted in 2003 but has resumed end of 2004. The selected hydrometallurgical process will use sulfuric acid. After acid leaching , nickel and cobalt will be separately extracted using organic solvents.
A second project is being studied in the North based on the Koniambo massif saprolitic nickel resource. Process to be used would be electric smelting.