Mechanism of surface morphology evolution in the reduction of fine iron ore in a conical fluidized bed reactor

Surface morphology evolution in the reduction of fine iron ore in a conical fluidized bed reactor under various conditions was investigated. Regime diagrams of morphology on iron ore reduction with H2 were obtained for choosing appropriate operating condition. The result indicates that it is beneficial to inhibit the formation of iron whiskers under high H2 content, high gas velocity and low reduction temperature. Further, the formation mechanism of the whiskers in the iron ore reduction with H2 atmosphere was revealed by the quantitative analysis of the relative rate between the iron diffusion and reduction. The result indicates that iron diffusion rate is the dominant factor that brings about whiskers during the reduction. Based on the regime diagrams of morphology, the formation of whiskers could be inhibited with the guidance of a whisker formation tendency value below 2.51 m4·mol−1. This provide a method of guidance for the application on iron ore reduction process by adjusting the relative rate between diffusion of iron and reduction. © 2020 Elsevier Ltd