Evaluation of reduction behavior of blast furnace dust particles during in-flight process with experiment aided mathematical modeling

Abstract

• BF dust particle velocity variation and residence times in the reaction zone are evaluated accurately. • Detailed BF dust particle thermal history during the in-flight reduction process is determined. • Transformation of the reduction degree of BF dust particle is found when particle temperature is over than 1640 K. • An iterative algorithm is developed to improve prediction accuracy of the mathematical model. In-flight reduction technology is a flexible process that allows recycling of the fine iron bearing metallurgical dusts efficiently. In this work, a mathematical model, incorporating introduced experimental kinetic parameters, was developed to accurately evaluate the reduction behavior of blast furnace (BF) dust particles during flight. A detailed evaluation of particle residence time, thermal history and reduction degree conversion were used to eliminate the deviations related to the assumptions of constant particle velocity and temperature in the experiment. The results show that the particle velocity decreases along the longitudinal direction of the reactor for a long distance and reaches a constant low velocity at the middle part of the reaction zone. The calculated particle residence time is 0.15–0.44 s less than the experimentally estimated value. The particle temperature reaches the isothermal temperature at the 0.15 m position from the reaction zone bottom. An obvious transition of reduction degree of dust particle is found when particle temperature reaches over 1640 K. The prediction accuracy of the model was improved by using the optimized kinetic parameters, namely pre-exponential factor and activation energy.