Recycling of Blast Furnace Flue Dust with In-flight Reduction Technology: Reduction Behavior and Kinetic Analysis

Abstract

Blast furnace (BF) flue dust is a by-product and collected from the gas cleaning systems during the blast furnace ironmaking process, which can be recycled as one of the secondary sources due to the valuable contents of iron and carbon. A novel in-flight reduction technology is considered to allow utilizing the large quantities of fine iron-bearing metallurgical dust directly to bypass the sintering/pelletization and conventional coke-making steps. In this work, the reduction behavior and kinetic mechanism of the blast furnace dust during in-flight process in hydrogen atmosphere are studied with lab-scale high-temperature drop tube furnace. The effects of temperature and gas composition on the reduction degree are examined. With the morphological observation, it is found that the unreacted shrinking core model can describe the in-flight reduction process. According to the kinetic analysis, the rate-controlling step is determined as the chemical reaction at the particle surface. The activation energy Ea is determined to be 224.8 kJ/mol and the pre-exponent factor A as 7.2 × 106 m/s.