Regular Article

Effect of B₂O₃ on the carbothermal reduction of vanadium titanium magnetite

¹ School of metallurgy engineering, Xi’an university of architecture and technology, 710055 Xi’an, Shaanxi, PR China
² Research center of metallurgical engineering technology of Shaanxi Province, 710055 Xi’an, Shaanxi, PR China

^* e-mail: 19778401@qq.com

Received: 5 July 2019
Accepted: 20 September 2019

Abstract

The effect of B₂O₃ on the carbothermal reduction of vanadium titanium magnetite was investigated under different temperatures by isothermal experiments. XRD analysis, SEM analysis and kinetic analysis were used to reveal the mechanism of B₂O₃ in the reduction process. The results showed that B₂O₃ could accelerate the reduction rate of vanadium titanium magnetite, and the suitable addition amount was 3%. B₂O₃ was easy to melt during carbothermal reduction, B³⁺ diffused into the crystal lattice of ferrotitanium compound, resulting in a decrease in binding energy and an increase in lattice parameters. B₂O₃ had also an erosion effect on the surface of the iron ore, and the contact area between reducing agent CO and vanadium titanium magnetite increased, thereby promoting the reduction. Low melting point compound CaO ∙ B₂O₃ formed after adding B₂O₃, which could improve the fluidity of the system and change the melting point of non-ferrous phase to further promote the growth and aggregation of iron particles. The reduction process was firstly limited by the first-order chemical reaction, then it was controlled by three-dimensional diffusion of reactants. The activation energy calculated by the best model was smaller than that of without adding B₂O₃.