Optimization of lime slurry spraying parameters to prevent high-temperature sticking of pellet ore

The sticking of iron ore pellets during blast furnace smelting presents a major challenge for high-proportion pellet utilization. The sticking mechanisms and the inhibitory effect of lime slurry spraying were investigated. Results indicate that sticking is primarily caused by the consolidation of low-melting-point compounds that form a liquid phase and the intergrowth of porous metallic iron. An increase in reduction temperature significantly aggravates this process. Experi-ments demonstrate that spraying lime slurry effectively suppresses sticking, with its effectiveness enhancing as the spraying concentration, dosage, and frequency increase. However, this treatment reduces the metallization rate and reduction degree of the pellets. The mechanism involves the formation of a compound layer, primarily consisting of CaSiO₃ and CaFeSi₂O₆, on the pellet surface. This layer mitigates sticking by preventing direct contact between metallic iron particles but simultaneously inhibits the reduction reaction of iron oxides by furnace gas. Therefore, optimizing the spraying parameters is essential in practical applications to balance the suppression of sticking against the loss of reduction performance. Based on experimental results, the recommended parameter range is a lime slurry concentration of 1%-4% and a spray dosage of 1%-3% (single spraying pass), which significantly reduces the sticking index while maintaining a high metallization rate.