The thermal stability of pellets required by steel mills refers to the ability of pellet ore to maintain relatively stable physical and chemical properties during heating, without obvious phenomena such as cracking, pulverization, softening or melting. The following is a detailed introduction: Aspects of performance
1、 Dimensional and shape stability: Pellets can maintain their original size and shape at high temperatures, without obvious expansion, contraction, deformation or fragmentation caused by factors such as thermal stress. For example, in the blast furnace ironmaking process, if the thermal stability of pellets is poor, they may break into small pieces or powder in the high-temperature zones inside the furnace, which affects the permeability of the burden column in the furnace and the smooth operation of the furnace condition.
2、 Strength stability: Pellets can maintain a certain level of mechanical strength in high-temperature environments without a sharp decline in strength. Sufficient strength is necessary to withstand the pressure from the upper burden in the blast furnace and the forces caused by rising gas, etc., preventing pellets from breaking due to collision and extrusion during transportation, charging and smelting processes.
3、 Chemical stability: The chemical composition of pellets remains stable at high temperatures, without excessive chemical reactions such as oxidation, reduction or decomposition, so as not to affect the performance of the pellets and subsequent ironmaking processes. For instance, iron oxides in some pellets should be reduced according to the expected reaction path at high temperatures, rather than undergoing abnormal reactions that lead to changes in pellet performance.
