Migration behaviors and kinetics of phosphorus during coal-based reduction of high-phosphorus oolitic iron ore

To understand the migration mechanisms of phosphorus(P) during coal-based reduction, a high-phosphorus oolitic iron ore was reduced by coal under various experimental conditions.The migration characteristics and kinetics of P were investigated by a field-emission electron probe microanalyzer(FE-EPMA) and using the basic principle of solid phase mass transfer, respectively.Experimental results showed that the P transferred from the slag to the metallic phase during reduction, and the migration process could be divided into three stages: phosphorus diffusing from the slag to the metallic interface, the formation of Fe–P compounds at the slag-metal interface and P diffusing from the slag-metal interface to the metallic interior.The reduction time and temperature significantly influenced the phosphorus content of the metallic and slag phases.The P content of the metallic phase increased with increasing reduction time and temperature, while that of the slag phase gradually decreased.The P diffusion constant and activation energy were determined and a migration kinetics model of P in coal-based reduction was proposed.P diffusion in the metallic phase was the controlling step of the P migration.