Application of DRI in electric furnace

Keywords:

Source: internal company

Direct reduced iron is a high-quality raw material for smelting electric furnace steel. Its addition affects the smelting time, energy consumption, molten steel yield and residual elements in electric furnace steelmaking. The development of direct reduced iron is conducive to achieving energy conservation and emission reduction, green development, and the transformation and upgrading of the steel industry.

Direct reduced iron (DRI) is a highly metallized iron-containing product obtained by reducing iron ore or oxidized pellets with a reducing agent (coal or coal gas) at a temperature lower than its melting point to remove oxygen from the iron ore. The resulting DRI product is very porous in nature, so it is also called sponge iron. Because its product has low content of harmful elements such as S, P, Cu, and Zn and high iron purity, it is a pure iron material for smelting high-quality steel and special steel, and is also the main raw material for high-end casting, ferroalloys, powder metallurgy and other industries.

1. Types of direct reduced iron

Direct reduced iron is mainly divided into cold DRI, hot briquette iron(HBI), and hot DRI

Type	Cold DRT	HBT	hot DRI
Form	Pellets or lumps	Cylinders or blocks	Pellets or lumps
True density	3.5g/cm³	5g/cm³	3.5g/cm³
Bulk density	1.55~1.9g/cm³	2.5~3.0g/cmcm³	1.55~1.9g/cm³
Dimensions	φ4~40mm	110X50X30mm	φ4~40mm
Metallization rate	92~95%
C	~4%
P	10.005~0.09%
S	0.001~0.03%
Gangue	2.8~6.0%
Residual elements	Trace
Temperature	Room temperature	Room temperature	≥550℃
Subsequent users	EAF/Converter	EAF/Converter/BF	EAF
Feeding method	Continuous or intermittent
Instructions	Cold DRI is suitable for use in nearby electric furnaces. It can also be transported to other places by rail or road after taking appropriate protective measures. Sea transportation is not recommended.	Hot briquette DRT is a preferred method, especially as the main method for long-term storage and transportation. Hot briquette DRI is usually used in electric furnaces, and can also be used in blast furnaces or converters.	Hot DRI is directly discharged from the reduction furnace in a hot state and sent to an electric furnace for melting, which can increase the user's output and reduce production costs.

2. Advantages of direct reduced iron

• DRI can be used as a substitute for high-quality scrap steel to supplement the shortage of scrap steel.
• Reduce impurity elements in steel and produce high-quality steel. As the raw material of electric furnace steel, scrap steel has a large fluctuation in chemical composition due to its different sources, which is difficult to control and brings difficulties to electric furnace steelmaking operations. At the same time, the quality of scrap steel has been declining due to the increasing proportion of non-metallic materials and non-ferrous metals in steel. If a certain proportion of direct reduced iron is used with scrap steel, it can not only increase and improve the composition of molten steel, but also improve and enhance the physical properties of steel, thereby achieving the purpose of producing high-quality steel.
• The content of other metal elements in reduced iron products except iron is low, and S and P are generally within 0.03%. It is a pure steelmaking raw material. There is no need to add auxiliary materials to remove impurities, which reduces steelmaking costs and smelting time.
• DRI has a low content of harmful elements and high iron purity, which is conducive to energy conservation, emission reduction and green development.