Regular Article

Study of the reduction mechanism of ironsands with addition of blast furnace bag dust

¹ School of Metallurgical Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, P.R. China
² Research Center of Metallurgical Engineering and Technology of Shaan Xi, Xi'an University of Architecture and Technology, Xi'an 710055, P.R. China
³ The University of New South Wales, School of Chemical Engineering, Sydney 2032, Australia

^* e-mail: 2586548110@qq.com

Received: 15 June 2017
Accepted: 8 December 2017

Abstract

To improve the reduction properties of ironsands carbon-containing briquettes, the behavior of ironsand during reduction by the addition of blast furnace bag dust (BFBD) is studied using a high temperature resistance furnace, X-ray diffraction (XRD) analysis and scanning electron microscopy. Additionally, the reduction mechanism is discussed in this study. The results showed that the reduction level and compressive strength of ironsand carbon-containing briquettes could be promoted by increasing the proportion of BFBD. When the addition rate of BFBD was 31.25%, the metallization rate and compressive strength increased from 82.1% and 21.5 N/a to 91.4% and 172.5 N/a, respectively. Metallic iron reduced from BFBD particles favored the carbon gasification reaction, which enhanced the internal CO concentration, and then promoted the FeTiO₃ reduction to Fe in ironsand. Meanwhile, a large amount of the liquid phase generated during the reduction process also favored Fe²⁺ diffusion, spread of iron joined crystals and the growth of crystals, which resulted in the improvement of the compressive strength of the ironsand carbon-containing briquettes.