Preparation of ferrochromium nitride via reduction and nitridation of chromite spinel with ammonia gas.

Ferrochromium nitride is an important alloying additive for smelting nitrogen–containing steel. Preparing nitrides by using ammonia gas as reducing and nitriding agent is characterized by high–efficiency and carbon free. In this study, the reaction behavior between chromite spinel and ammonia gas was investigated. Thermodynamic analysis revealed that the reaction was feasible. The transformation of chromite spinel as well as the final products were dependent on reaction temperature, time and input fraction of ammonia gas. The experimental results proved the effect of reaction parameters on the reduction and nitridation process. Chromite spinel was reduced and nitrided to form metallic iron and CrN at temperatures below 950 °C, while metallic iron and Cr 2 N were the main products at 1000 °C. XPS analysis also proved the existence of CrN and Cr 2 N. Ferrochromium nitride with N content treater than 15 wt% was obtained when reducing above 950 °C for 3 h. [Display omitted] • Ammonia gas is a high-efficiency and carbon-free agent that is used for reducing and nitriding. • The transformation of chromite spinel is revealed in this study. • Ferrochromium nitride is prepared by using ammonia gas as reducing and nitriding agent. • Mechanism on reaction between chromite spinel and ammonia gas is revealed. [ABSTRACT FROM AUTHOR]