The EAF requirements for DRI physical and chemical properties
(From "Steel production technology and equipment new technology")
Because there are many DRI production method, but the raw material is different, thus the physical and chemical properties of the obtained products have changes within a certain range, to make steel more economical, the more stable steel quality, we must have some requirements for DRI physical and chemical properties.
1. The content of DRI Total Iron TFe is more than 88%, Metal iron MFe is more than 80% , metallization M ratio is more than 90%. (Metallization rate refers to: the ratio of Metal in total Fe, it means the reduced level of iron oxide, M=MFe/TFe×100%）. During EAF steel making, the M high the better, M high means metal Fe contains high, or else will decrease metal recovery during steel making. According to Qatar steel company EAF using DRI introduction, the capacity of EAF will change with the change of M, once the M is lower than 94%, all data will rapidly drop, According to their experiment testing, each 1% of decrease M in sponge iron, will increase 8-10 kw·h/t.
2. The gangue (SiO2, Al2O3, CaO, MgO, MnO, etc.) as low as possible, generally less than 3% to 5%. High gangue content will cause an increase in the amount of slag, in addition, FeO high, it can lead to boiling and lead the metal recovery decrease, leading smelting time and power consumption increases.
3. The content of S, P is as low as possible. It depends on the quality of the ore and direct reduction method.
4. Other harmful elements (Cu, As, Sb, Zn, Cr, Ni, Mo, etc.) is as low as possible, in the iron content is very low, most is at trace levels
5. The density in the range of 4.0 ~ 6.0g / cm3, between the slag (2.5 ~ 3.5g / cm3) and liquid steel (7.0g / cm3)
6 Bulk densities is more than 2.7t / m3
7. Size: General requirements between 8 to 100 mm. Do not contain dust and too large size at the same time, less than 3 to 7 mm DRI must be CBI for steelmaking.
8. Strength: to ensure transport into the furnace not be easily broken the cold compressive strength is greater than 70Mpa,some require drum strength 。