The EAF steelmaking energy will consume more energy after adding the DRI, there are the following reasons.
The energy consumption of electric arc furnace (EAF) steelmaking increases after the addition of direct reduced iron (DRI) due to the following reasons:
- Melting DRI requires more energy. The lower the metallization rate of DRI, the higher its FeO content. The reduction of FeO during the EAF process is an endothermic reaction, which absorbs heat and increases energy consumption.
- The gangue content in DRI, particularly SiO₂, has a significant effect on energy use. A higher SiO₂ content increases power consumption. Moreover, to maintain slag alkalinity, more quicklime must be added to balance the higher SiO₂ content, leading to increased slag volume. Melting this additional slag consumes extra energy.
- DRI with high carbon content also affects power consumption, although the impact varies depending on process conditions.
- Continuous feeding of DRI, matched with a synchronized power supply, helps shorten the smelting cycle and allows the furnace to operate at maximum power input, improving EAF productivity. In contrast, batch feeding—especially when DRI is concentrated or placed near the furnace wall—can lead to material buildup or bonding on the wall, significantly extending melting time and increasing electricity consumption.
- The temperature of the DRI charge greatly affects power consumption. Using fully cold sponge iron increases electricity usage compared to scrap smelting. However, when using fully hot-charged DRI, energy consumption becomes comparable to that of full scrap smelting. The impact on the smelting cycle, however, is relatively minor.
To reduce energy consumption in EAF steelmaking with DRI, steel mills have adopted several measures. These include preheating the DRI—while taking precautions to avoid secondary oxidation—and prioritizing DRI with a high metallization rate and low SiO₂ content.
