<p>The clean and efficient utilization of semi-coke (SC) offers substantial significant social benefits. In this study, SC was employed as the primary feedstock to investigate the effects of particle size and blending with different carbon-based reducing agents on reactivity under a carbon dioxide atmosphere. In addition, SC was blended with carbonaceous reducing agents commonly used in industrial silicon smelting at mass ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 to evaluate the reactivity evolution of the blended materials. Kinetic and thermodynamic analyses, together with reactive index evaluation, were used to track the changes in reaction activity. The structural evolution of the blended samples subjected to different temperature treatments was characterized through Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. The results demonstrated that decreasing particle size enhanced SC reactivity. Furthermore, when SC was blended with low-rank non-coking coal or charcoal, the reactivity indices of the mixtures exhibited an overall increasing trend as the blending ratio increased from 9:1 to 5:5, accompanied by a continuous reduction in activation energy. The activation energy of the 5:5 mixture decreased by 10.90% and 29.73%, respectively, compared with that of the 9:1 mixture, indicating a pronounced improvement in reactivity. Increasing temperature facilitated a higher degree of graphitization in the blended carbon materials, leading to a more ordered microcrystalline structure. These findings offered useful insights and practical guidance for the rational selection and optimization of carbon-based reducing agents in industrial silicon smelting processes.</p> Graphical Abstract <p></p>