Trade-off between physical and metallurgical properties of dr iron ore pellets
Jean Philippe Santos Gherardi de Alencar
Abstract
This study investigates the trade-off between mechanical strength and metallurgical performance in direct reduction (DR) iron ore pellets, a critical challenge in pellet design. A statistically structured experimental design was applied to evaluate the influence of key process parameters - carbon content in green pellets, anthracite particle size, and grate speed - on compressive strength (CCS) and metallization degree (Met). Physical, metallurgical, and microstructural characterizations were conducted, including porosity analysis and optical microscopy. Regression models were developed using ordinary least squares (OLS) to quantify the relationships between process variables and pellet properties. The model for CCS showed moderate predictive power (R2 = 0.50), while the model for Met demonstrated a strong fit (R2 = 0.80), with carbon content and grate speed emerging as statistically significant predictors. These models revealed a clear inverse correlation between CCS and Met, indicating that higher mechanical strength, while beneficial for handling and durability, can hinder gas diffusion and reduce reduction efficiency due to lower porosity and fewer reactive sites. The findings were validated through industrial-scale basket tests in a Midrex reactor, confirming the laboratory trends and reinforcing the importance of data-driven strategies for optimizing pellet performance
Keywords
References
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Submitted date:
09/24/2025
Accepted date:
12/02/2025
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