The iron and steel industry is a major CO₂ emitter and an important subject for the implementation of carbon emission reduction goals and tasks. Due to the complex ore composition and low iron grade, vanadium–bearing titanomagnetite smelting in a blast furnace consumes more coke and emits more carbon than in an ordinary blast furnace. Injecting hydrogen–rich gas into blast furnace can not only partially replace coke, but also reduce the carbon emission. Based on the whole furnace and zonal energy and mass balance of blast furnace, the operation window of the blast furnace smelting vanadium–bearing titanomagnetite is established in this study on the premise that the thermal state of the blast furnace is basically unchanged (raceway adiabatic flame temperature and top gas temperature). The effects of different injection amounts of hydrogen–rich gases (shale gas, coke oven gas, and hydrogen) on raceway adiabatic flame temperature and top gas temperature, and the influence of blast temperature and preheating temperature of hydrogen–rich gases on operation window are calculated and analyzed. This study provides a certain theoretical reference for the follow–up practice of hydrogen–rich smelting of vanadium–bearing titanomagnetite in blast furnace.

In this paper, the effect of titanium carbonitride (Ti(C,N)) on the viscosity of high-titanium-type blast furnace slags was investigated. The different Ti(C,N) contents were achieved by adjusting the reduction degree of TiO₂ to reflect the real characteristics of the high-titanium slag. The results show that the viscosity of the slag increased with the increasing Ti(C,N) content and decreased with the rising temperature. A deviation between the measured and the fitted viscosity appeared as the content of the Ti(C,N) was beyond 4 wt%. Furthermore, the apparent viscous flow activation energy of the slag ranged from 106.13 kJ/mol to 235.46 kJ/mol by varying the Ti(C,N) contents from 0 wt% to 4.97 wt%, which was evidently different from the results of previous studies. The optical microscope and energy dispersive X-ray spectroscopy (EDS) analysis show that numerous bubble cavities were embedded in the slags and the Ti(C,N) particles agglomerated in the solidified samples. This phenomenon further indicates that the high-titanium slag is a polyphase dispersion system, which consists of liquid slag, solid Ti(C,N) particles and bubbles.