Influence of Chromite Ore Selection on the Pelletized Oxidative Sintering Process: A South African Case Study

The smelting of chromite to produce ferrochrome (FeCr) and subsequently, stainless steel, is an energy-intensive carbothermic process. Various countries apply the Outotec FeCr process, which employs oxidative sintering in air to produce mechanically strong chromite pellets. During this process, iron (Fe) is liberated from the chromite spinel due to the elevated temperatures and oxidative nature of the process. It is well understood that oxidatively altered chromite requires less energy to be smelted when compared to non-oxidized chromite. This study showed that sintered pellets obtained from five South African pellet sintering plants had vastly different oxidative alteration penetrations. Additionally, sintered pellets from the same plant may also vary significantly. It was further shown that ores mined from various locations in South Africa had dissimilar sintering behaviors, suggesting that sintered pellets should be characterized before smelting to determine the extent of oxidative alteration. The benefit of a smelter consuming oxidized ore was also demonstrated by comparing the interaction between oxidized and non-oxidized chromite with a carbon (C) source.