Pilot plant production of ferronickel from nickel oxide ores and dusts in a DC arc furnace

Abstract

Laterites and other oxidized nickel ores constitute a very important part of world-wide nickel reserves. The development of nickel oxide ore smelting has drawn heavily on iron and steel metallurgy. In ferronickel production, the nickel oxide and part of the iron oxide are reduced to metal in an electric furnace to form immiscible layers of slag and metal. The crude ferronickel is tapped from the furnace and refined to saleable ferronickel by conventional techniques. Because of the high moisture content (free and chemically bound water) and because water requires so much energy to evaporate and heat up, it is clear that dehydration is required before smelting the ore in an electric furnace. Due to the physical properties of the ores, a large fraction of fines is generated during the pre-treatment stages. In the conventional production of ferronickel from these ores, much fine material is produced which cannot readily be accommodated directly in existing three-electrode or six-in-line AC furnaces. DC-arc furnace technology allows ore particles less than 1 mm in size to be treated directly thereby improving the overall recovery of nickel without the need for expensive agglomeration techniques.