Patents
The invention relates to a process for recovery of Ni and other metal values in the form of ferronickel alloy and alloyed pig iron from chromite overburden. In work, an attempt has been made to enhance the Nickel content in Chromite overburden by pyrometallurgy route, i.e., reduction roasting by pan sintering, followed by magnetic separation and plasma smelting. The Ni content is enriched from 0.7 to 1.32 by reduction roasting and further enriched to 1.45 Ni by magnetic separation. The magnetic fraction can be used as raw material for high-grade FeNi production. The enriched COB is smelted in a thermal reactor to form immiscible layers of slag and metal by varying basicity, time and using appropriate reductant. The obtained ferronickel alloy contains 8 to 10 Ni. The remaining iron and other metal values, including chromium and nickel, present in the slag are removed in the form of alloyed pig iron by plasma smelting process and the slag can be utilized as a raw material in cement making.