The suboptimal kinetic conditions of metallurgical reactions within the molten pool have long been a persistent technical challenge in the realm of electric arc furnace (EAF) steelmaking.
The inadequate agitation intensity of the molten bath in EAF steelmaking is closely related to the inherent characteristics of the furnace design. Traditional EAFs primarily utilize scrap steel as the fundamental raw material, relying mainly on electrical energy, supplemented by chemical energy, to produce qualified molten steel. As a result, these furnaces are typically designed with a large furnace volume and a relatively shallow molten pool. For instance, when comparing a 100 - ton EAF to a converter of the same capacity, the height - to - diameter ratio of the EAF is merely 53% of that of the converter.
In general, a larger height - to - diameter ratio enables a furnace to withstand a greater oxygen supply strength. However, in the case of EAFs, factors such as the melting of scrap steel and the flow of slag from the furnace door further constrain the stirring intensity of the molten bath. The stirring intensity in an EAF bath is only 10% - 20% of that in a converter.
The stirring strength of the molten pool can be effectively characterized by the flow rate of the molten steel. To gain a deeper understanding, a numerical simulation approach was employed to model the flow of molten steel in a 100 - ton EAF. The simulation results revealed that the average flow velocity of molten steel in the EAF was a mere 0.06 m/s. In contrast, the average flow velocity of molten steel in a 100 - ton converter was 0.31 m/s. This stark difference clearly indicates that the stirring strength of the molten pool in an EAF is significantly lower than that in a converter.
In actual production scenarios, when compared to converter steelmaking, there are noticeable disparities in smelting consumption and production costs between EAF steelmaking and converter steelmaking. At the end of the steelmaking process, several key indicators, including carbon and oxygen content, as well as slag (FeO) content, serve as crucial reflections of the stirring strength of the molten pool. These indicators also have a profound impact on the quality of the final steel product.
By analyzing data provided by numerous advanced steel companies, which included the end - point carbon content, oxygen content, and final slag (FeO) content from both EAF and converter smelting operations, it was found that the average end - point carbon - oxygen content in EAF steelmaking was approximately 0.0032. Moreover, the average final slag (FeO) content in EAF steelmaking exceeded 22.00%, which is higher than that observed in converter steelmaking.
In conclusion, the low stirring intensity of the molten bath in EAFs, stemming from the limitations imposed by the furnace type and smelting process, acts as a significant bottleneck that restricts the technological advancement of EAF steelmaking. To overcome this challenge, further research and development efforts are required to optimize furnace design and smelting processes, thereby enhancing the kinetic conditions within the molten pool and improving the overall performance of EAF steelmaking.
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