The influence of water content on the kinetics and mechanisms of hydrogen reduction using industrial iron ore pellets at 873 K - 1173 K

Abstract

This work aims to study the effect of pH₂O in the atmosphere during hydrogen reduction of iron oxide over a temperature range relevant to industrial practice. To further the industrial context, industrially produced hematite iron ore pellets are utilized. A resistance heated furnace was employed to conduct experiments, in the temperature range 873 K – 1173 K. A water vapor generator was used to control water vapor partial pressure during hydrogen reduction in the range 0-15% pH₂O. The system was carefully designed to ensure precise control of the water content in the reaction gas. Thermal Gravimetric Analysis (TGA) was used to follow the reduction of the iron ore pellets. To understand the reaction mechanisms, Scanning Electron Microscopy (SEM) was used to study the microstructure of partially reduced pellets. Results suggest the reduction rate is profoundly affected by water at 873 K, less so when the temperature is increased. The microstructure is also highly affected by pH₂O at 873 K, at higher temperatures the microstructure is less affected. The influences of gas dilution and chemical reaction rate on these aspects are discussed.