Changes of Hot Compressive Strength of Iron Ore Pellets During Reduction Process and Mechanism

In order to research the compressive strength of pellets in blast furnace, pellets were tested in a neutral and reducing atmosphere at different temperatures and reduction degrees by using self-designed and manufactured high-temperature strength and creep solid materials online tester. The results show that: in neutral atmosphere, when the temperature reaches 1 000 ℃, the compressive strength is over 2 750 N. With the temperature increasing, there is a sharp decline on the compressive strength; in reducing atmosphere, there is a significant strength decrease between the initial reduced pellets than the pellets in neutral atmosphere at same temperature. When the temperature is up to 900 ℃, the strength is only 1 250 N and the fragment pellets are more likely powdering. The microstructure analysis indicates that the growth of lattice, the new iron with increased porosity and cracks, and the weakness of particle bonding cause the decrease of compressive strength.