In Electric Arc Furnace (EAF) steelmaking, Direct Reduced Iron (DRI) is often considered a supplementary charge material when scrap availability is limited. However, in practical operation, the use of DRI imposes strict requirements on raw material quality, charging practice, process control, and plant management.
For many small- and medium-sized EAF steelmaking projects, these requirements may significantly increase operational complexity and risk, without necessarily delivering clear economic benefits.
Based on practical steelmaking experience and project operation data, this article reviews the key technical requirements for using DRI in EAF steelmaking, its charging behavior, and its impact on major metallurgical indicators. It also explains why, in most projects, DRI is not recommended as a preferred charge material.
Basic Technical Requirements for DRI in EAF Steelmaking
To ensure stable and controllable EAF operation, DRI used for steelmaking should meet several fundamental requirements.
Density and mechanical strength
The bulk density of DRI is typically required to be within 4.0–6.5 g/cm³, with sufficient cold-state strength to avoid excessive breakage and fines generation during transportation, storage, and charging. Excessive fines increase dust losses and reduce effective metallic yield.
Appropriate size distribution
DRI should neither contain excessive fines nor oversized pellets. Fine particles are easily oxidized or extracted by the dedusting system, while oversized material negatively affects uniform charging and melting efficiency. In practice, a particle size range of 10–100 mm is commonly adopted.
Controlled impurity and gangue content
High gangue content in DRI increases lime consumption for slag formation, leading to higher slag volume, increased power consumption, and reduced technical and economic performance. Low gangue content is therefore a basic prerequisite for DRI application in EAF steelmaking.
Adequate metallization rate
The metallization rate, defined as the proportion of metallic iron to total iron, has a direct impact on power consumption and metal yield. Lower metallization means higher residual FeO, which requires additional electrical energy and reductants for reduction, while simultaneously reducing overall metallic yield.
Charging Behavior and Melting Characteristics of DRI
The density of DRI lies between that of slag and molten steel. After charging into the furnace, DRI tends to remain at the slag–metal interface. While this can be beneficial for interfacial reactions under certain conditions, it also imposes stricter requirements on charging practice.
When the DRI ratio is relatively low (generally below 30%), it can be charged together with scrap. In practical operation, light scrap is placed at the bottom of the bucket, followed by heavy scrap and DRI. This arrangement helps prevent DRI from accumulating near the furnace wall or cold zones, where it may form unmelted agglomerates.
When large batches of DRI are charged, its slow heat transfer and poor melting behavior become more pronounced. If the electric arc does not directly heat a thick DRI layer, molten metal may solidify between pellets, forming sintered clusters that hinder further penetration and melting. This significantly extends melting time and worsens technical and economic indicators.
Therefore, when higher DRI ratios are applied, continuous charging through the furnace roof is often required. Charging ports located at the furnace center or mid-radius allow DRI to enter the high-temperature zone with sufficient kinetic energy to penetrate the slag layer and improve melting efficiency.
Carbon Content of DRI and Its Influence on Process Control
The carbon content of DRI varies significantly depending on the reduction process, and this directly affects EAF process control.
Gas-based DRI production allows relatively precise control of carbon and residual FeO, resulting in so-called “balanced DRI.” In such cases, additional carbon is usually unnecessary during melting, and DRI neither significantly increases bath carbon nor imposes a heavy FeO burden.
Coal-based DRI generally contains lower carbon levels. During steelmaking, additional carbon must be charged according to metallization rate and steel grade requirements to ensure proper bath formation and FeO reduction. This narrows the operational window and increases reliance on operator experience and management discipline.
Impact of DRI on Power Consumption and Metallic Yield
Statistical data and operating experience indicate that the use of DRI in EAF steelmaking generally leads to increased electrical energy consumption, especially when the DRI ratio exceeds approximately 25%. The extent of this increase depends on DRI carbon content, metallization rate, and carbon adjustment strategy.
Metallic yield is strongly influenced by carbon–oxygen balance control. Increasing bath carbon, applying multi-point carbon injection, and coordinating carbon–oxygen lances help reduce FeO content in slag and promote the reduction of FeO from DRI into molten steel. When combined with a suitable proportion of hot metal charging, metallic yield can be further improved.
From the perspective of slag volume, the impurity level introduced by DRI is generally comparable to that of scrap. When the DRI ratio is kept below 30%, its impact on slag quantity is usually limited.
Effects on Melting Time, Electrode Consumption, and Oxygen Consumption
In all-scrap EAF operation, the increased power demand associated with DRI typically leads to longer power-on time, extended melting cycles, and higher electrode consumption.
In contrast, when hot metal charging is applied, a reasonable DRI addition can accelerate decarburization. With proper power curve control, the melting cycle does not necessarily increase and may even be slightly reduced in certain operating conditions.
The FeO carried by DRI promotes slag melting and accelerates decarburization reactions. As a result, overall oxygen consumption often decreases, typically by 0.5–3.5 m³/t in industrial practice.
Safety Considerations When Using DRI in EAF Steelmaking
When DRI with low carbon content and low metallization is used in excessive proportions, FeO may accumulate in the slag. Improper operation can lead to violent bath boiling and serious safety incidents.
Additionally, DRI may form unmelted “icebergs” in the furnace. In severe cases, these can block the tapping hole during tapping, compromising tapping safety and production stability—an especially critical issue for small- and medium-sized EAF operations.
Why DRI Is Generally Not Recommended in Most EAF Projects
Based on engineering practice and production management experience, DRI is not considered an optimal charge material for most small- and medium-sized EAF steelmaking projects, for the following reasons:
- From an energy and yield perspective, DRI typically delivers lower metallic yield than hot metal, while still requiring the removal of non-metallic components, limiting its economic advantage.
- Except for carbon, most compounds in DRI ultimately enter the slag, increasing lime consumption and slag volume as gangue content rises.
- High-carbon DRI or DRI with metallization below approximately 90% carries an increased risk of severe bath boiling if not properly controlled.
- DRI has a highly porous structure and high chemical reactivity. It is difficult to transport and store safely, with risks of oxidation and self-heating when exposed to air or moisture. In many cases, briquetting (HBI) is required to mitigate these risks, increasing logistical and management demands.
In practice, DRI is better suited to steelmaking systems where DRI production and EAF operations are closely integrated and hot charging can be realized. However, most small- and medium-sized EAF projects lack nearby DRI supply and the management infrastructure needed to ensure safe storage and stable operation, significantly increasing operational risk.
SME Group’s Engineering and Production Management Experience
It is important to note that steelmaking project production management and operational optimization are core businesses of SME Group. Beyond delivering turnkey steel plant projects, many clients continue to engage SME Group for long-term production operation and technical management services.
Regardless of the charge mix selected by the client, SME Group focuses on systematically resolving technical issues during operation and ensuring that EAF steelmaking processes remain safe, stable, and sustainable under real project conditions.
