Ferronickel is typically refers to submerged arc furnace produced with 20%~ nickel content ferronickel alloys. Since major nickel ores are classified as pentlandite, sillimanite, goethite or pyrite, laterite and other forms, the smelting process of ferronickel alloys are quite different.
The smelting of nickel laterite ores to ferronickel alloy is unique in extractive metallurgy. It treats feed that is very low grade with respect to the target metal and, as a result, produces much more waste slag than valuable metal product. The energy consumption per tonne of product is therefore high and requires sustained research and design development in an effort to improve the economics of laterite smelting. In this work, the main characteristics of nickel laterite smelting are reviewed, and then a simple and transparent computational thermodynamics model of the electric furnace smelting step is developed. This model predicts the nickel grade, nickel recovery and FeO content of the slag as functions of the iron recovery to ferronickel satisfactorily. It correctly predicts that the carbon and silicon contents in ferronickel increase sharply at high iron recoveries. However, in common with more sophisticated models, it incorrectly predicts the iron recovery at which this increase is observed in practice. It is concluded that the model provides an accessible and a satisfactorily accurate vehicle for understanding the relationships between process variables and process outcomes during nickel laterite smelting.
In pyrometallurgy, ferronickel can be produced by two major process, one is rotary kiln with submerged arc furnace (RKEF) and another is sintering machine with submerged arc furnace.
Nickel pig iron production is a kind of reduction process of Nickel ore to Nickel pig iron products.
NPI, Nickel pig iron (NPI) is a low grade ferronickel invented in China as a cheaper alternative to pure nickel for the production of stainless steel. The production process of nickel pig iron utilizes laterite nickel ores instead of pure nickel sold on the world market.
Nickel pig iron consists low-grade nickel laterite ore, combined with coking coal and a mixture of sand and gravel aggregates. The mixture is then heated in the furnace. Chinese producers make use of either a blast furnace or an electric arc furnace, depending on the desired grade. In general, electric furnaces make higher grade NPI between eight and 15 percent nickel. This is already similar to the quality of ferronickel. While Blast Furnace smelting is more proper for production of NPI with low nickel content in laterite nickel ores and for the area of power supply limited. Which mainly consists of Pulverized Coal Injection System, Lime Kiln, Blast Furnace, sintering machine, BHL Hot Air Furnace and belt conveyors.
Nickel pig iron production by blast furnace and submerged arc furnace is a kind of new applications started in China.