Structure Analysis of Pellets with Different Reduction Degrees Using X‐Ray Micro‐Computed Tomography

Abstract

Pellets are raw materials for blast furnace (BF) production, and a comprehensive understanding of the reaction process of pellets is of great significance for the operational optimization of BF production, energy saving, and emission reduction. The present study focuses on the structural evolution of pellets at different reduction stages. Combined with micro‐computed tomography (micro‐CT), interrupted reduction experiments are designed to analyze the different reduction stages of the pellet. The effects of the gas composition and temperature on the reduction are investigated. The results demonstrate that the combination of interrupted reduction experiments and micro‐CT can effectively illustrate the internal information of the pellets at different stages. The reduction products of H2 are dense iron phases, resulting in a clear pore stratification inside the pellet, and the outer pores almost disappear. In addition, the internal structure of the pellet is complex and the degree of reaction is uneven. The cracks generated during the reduction reaction become gas channels, which lead to a higher local reduction rate than in the others. Notably, the reduction expansion of pellets at 1000 °C is faster than that at 700 °C and the surface cracking is more severe.