The Impact of Particle Size on the Electrical Resistivity of Burden in the Upper Zone of an EAF During Metallurgical-Grade Silicon Smelting

As the energy consumption problem of an electric arc furnace (EAF) is becoming more and more prominent, improving the furnace charge resistivity becomes the key to reducing the energy consumption of metallurgical-grade silicon smelting. This study systematically examines the impact mechanism of the particle size of raw materials on the electrical resistivity of metallurgical-grade silicon furnace burden. The results show that in the range of 700–1300 °C, the size of the furnace charge consisting of coal and silica ore decreases from 6–9 mm to 0.25–0.3 mm, and the resistivity of the furnace charge increases from 0.9–1366.7 Ω·m to 2.5–2060.5 Ω·m. The effects of particle size on furnace charge resistivity are clarified by investigating how particle size influences the resistivity of coal and silica ore, along with an analysis performed within the context of furnace charge resistivity modeling. Research shows that particle size plays a crucial role in affecting the resistivity of the furnace charge. This impact is largely due to alterations in the graphitization-like degree of coal and changes in the contact resistance between particles. Together, these factors significantly influence the overall resistivity of the furnace charge. During this process, the particle size increased dramatically from 0.25–0.3 mm to 6–9 mm. The coal ID/IG ratio (degree of graphitization-like) was reduced from 1.36 to 1.32. The resistivity of the coal decreased by 29%, while the contact resistance of the charge was reduced by a factor of 2. The resistivity of the charge itself was also reduced by 64%. This transformation highlights the significant changes in the coal’s properties aimed at optimizing operational efficiency. This study is of great significance in clarifying the scheme of regulating furnace charge resistivity through particle size optimization, which is an important guide for energy saving and carbon reduction in the industrial silicon smelting process.