Harmless treatment of waste selective catalytic reduction catalysts during iron ore sintering process

Abstract A substantial quantity of waste selective catalytic reduction (SCR) catalysts is produced as hazardous wastes owing to the ultra-low emission reform of coal-fired power plants. This study aims to propose a new method for large-scale harmless treatment of waste SCR catalysts for utilization during iron ore sintering process. The effects of adding waste SCR catalysts on green bed permeability, flame front propagation, mineral phase, microstructure, and sinter indexes were evaluated. Results showed that the addition of waste SCR catalysts decreased the concentrated distribution degree of granules and deteriorated green bed permeability, thereby leading to slower propagation of flame front and lower sintering bed temperature. Results of mineral phase and microstructural analysis revealed that less calcium ferrite and more skeletal hematite formed, and porosity decreased from 39.64% to 24.62% when the level of waste SCR catalysts added was increased from 0 to 10%. All sinter indexes, including flame front speed, productivity, yield, and tumbler index, decreased with the increase in the level of waste SCR catalysts added. A comprehensive index was adopted to systematically evaluate the influence of adding waste SCR catalysts. This index decreased from 100.0 to 2.9 as the level of waste SCR catalysts added was increased from 0 to 10%. Finally, the addition of 2% waste SCR catalysts is recommended to achieve high sinter quality.