Effect of TiO₂ addition on the sticking of pellets based on hydrogen metallurgy shaft furnace: Behavior analysis and mechanism evolution

Direct reduction process based on the hydrogen metallurgy gas-based shaft furnace is a promising technology for efficiently and low-carbon smelt vanadium-titanium magnetite (VTM). However, in the direct reduction process, sticking of pellets occurs due to the aggregation of metallic iron between the contact surfaces of adjacent pellets, which will have a serious negative effect on the continuous operation. This paper presents a detailed experimental study of the effect of TiO₂ on the sticking behavior of pellets during direct reduction process under different reduction conditions. The results showed that sticking index (SI) decreased linearly with increasing TiO₂ addition, which stemmed from the increase of unreduced FeTiO₃ during reduction, leading to decrease of the number and strength of metallic iron interconnections at the sticking interface. When the TiO₂ addition was raised from 0% to 15% at 1100°C, SI increased from 0.71% to 59.91%. The connection of slag phase could be attributed to the sticking at low reduction temperature corresponding to low sticking strength. Moreover, interconnection of metallic iron became the dominant factor as reduction temperature increased, and SI increased sharply. Additionally, TiO₂ had a great effect on SI at high reduction temperature compared to low reduction temperature.