Study on Quantitative Color Characterization and Color‐Property Relationships of Finished Iron Ore Pellets

The color of pellet ores is quantitatively characterized based on the colorimetric method. Multiscale structural characterization and detection experiments clarified the coloring mechanism and the color–structure–property relationship of iron ore pellets. The results reveal that the chromatic difference originates from the competition between surface optical reflection and internal reflection of hematite. Fully roasted blue pellets exhibit a bluish‐gray hue dominated by specular reflection due to densified surfaces (low porosity and high crystallinity), while under‐roasted red pellets display a reddish‐brown coloration amplified by internal reflection from porous structures (high porosity, surface roughness) and grain boundary defects. Quantitative colorimetry demonstrates that blue pellets possess significantly higher luminance (L*) and lower red/yellow chromaticity (a*, b*) compared to red pellets, confirming the correlation between color parameters and microstructure. Tests indicate that blue pellets exhibit 700–900 N/pellet higher compressive strength, yet their dense structure restricts CO diffusion, leading to 4–7% lower reduction swelling and 1–5% decreased reducibility. Linear regression models based on colorimetric parameters validate the feasibility of using optical characteristics to predict compressive strength ( R 2 = 0.794–0.823, p < 0.01). This work provides theoretical insights into optimizing pellet roasting processes and balancing color–structure–performance.