Iron ore pellet disintegration mechanism in simulated shaft furnace conditions

The disintegration behavior and mechanism of iron ore pellet in simulated shaft furnace conditions were investigated in details. Effects of temperature, reducing gas and gangue compositions were emphatically discussed. It was found that pellet disintegrated acutely as reduced by H-2/CO = 0.8 at 550 degrees C. Gangue minerals in pellet were proved to ease the disintegration in various degrees. SiO2 or CaO could remarkably lower reduction disintegration index (RDI). But the effect of MgO or Al2O3 was much weaker. Furthermore, intrinsic relation between disintegration and reduction was revealed from microstructure aspect. Results demonstrated that lattice transition stress and crack generation brought about by the low temperature reduction led to pellet structure failure and therefore disintegration. The reduction degree showed positive correlation with disintegration level of pellet. Low melting point phase formed by SiO2 or CaO lessened crack formation in pellet. However, MgO or Al2O3 could not play a similar role. (C) 2017 Published by Elsevier B.V.