A new process of smelting laterite by lowtemperature reduction and microwave irradiation

Abstract

A new smelting process for the reduction of laterite with a relatively high yield of Ni has been presented in this paper; particularly, this process has been underwent industrialized experiment in China. This new process was based on the following fundamental research results. (1) Since nickel oxide can be reduced more easily than iron oxide, the nickel content of the produced ferronickel alloy increases significantly when the quantity of coal that is mixed with laterite ore is optimized, leading to a right oxygen potential of gas for reduction reaction. (2) When laterite is reduced at 1150°C, only 75% of the reduced ferronickel product can be magnetically separated from slag, although more than 95% Ni has been reduced from laterite. (3) The key technology is to realize a fast carburization at 1300°C by microwave irradiation, which causes ferronickel fines grow to a large size in the semi-melting state so that they can be separated magnetically with a high efficiency. The first demonstration production line with an annual capacity of 100 kt green balls has been established in China. The Ni content reaches 13.5%, moreover, both P and S contents are also within the expected range.