Numerical simulation and optimization of flash reduction of iron ore particles with hydrogen-rich gases

Abstract

In this study, the flash reduction process of hematite particles with six hydrogen-rich gases of purified COREX (PCOREX), dry pulverized coal gasification (DPCG), water-coal slurry gasification (WCSG), Midrex, HYL-III, and reformed coke oven gas (RCOG) was investigated. The homogeneous and heterogeneous reactions occurring in the reduction temperature range were determined by thermodynamic analysis. On this basis, a three-dimensional computational fluid dynamics model was established to demonstrate the flash reduction process in a drop tube furnace and describe hematite particle characteristics during the in-flight reduction process. Results showed that a higher hydrogen content led to a faster reduction rate and a higher reduction degree. Hence, the reduction degree increased according to the following trend of PCOREX < DPCG < WCSG < Midrex < HYL-III < RCOG. In addition, a three-factor, three-level, Box-Behnken design was employed to develop a quadratic regression model for predicting the reduction degree of hematite particles in DPCG with different operating parameters, such as reduction temperature, particle size, and gas velocity. Optimization of operating parameters was done to achieve a hematite reduction degree >90%.