Enduring electric arc furnace optimization technology plays a part in steel’s sustainable future

In this article Frederik Esterhuizen, who heads up ABB's metals industry automation, electrification and digitalization business, discusses the latest developments in electromagnetic stirring technology together with Zaeim Mehraban, Global Sales Manager for ABB Metallurgy, and its benefits for the steelmaking industry. This is not a new technology, since it was first patented around 80 years ago, but ongoing advances mean it remains highly relevant today.

This article was first published in the September 2023 issue of Furnaces International

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Could you give a brief history on ABB and its role in the metals industry?

Frederik Esterhuizen (FE): ABB is a global technology leader with more than 130 years of history across industries, providing everything from the smallest electrical components to large motors and drives, powering mines, trains, paper mills and even cruise ships. In the metals industry, ABB leads the way in electrification and automation for our customers, enabling a more sustainable and resource efficient future. The company’s solutions, incorporating specific metallurgy products and digital, connect engineering know how and software to optimize how things are manufactured, moved, powered, and operated.

Zaeim Mehraban (ZM): ABB has been a leading supplier and a trusted partner to the metals industry for many decades, collaborating with steelmakers, producers, original equipment manufacturers (OEMs) and other suppliers to develop customer-specific solutions to increase productivity, efficiencies, quality, and safety, while also driving the transition towards more autonomous plants.

What is the role of an electric arc furnace in the future of the steel industry? 

ZM: The electric arc furnace (EAF) is expected to play a significant role in the future of the steel industry due to its flexibility, lower carbon emissions, resource efficiency, adaptability, and recycling capabilities. As the industry continues to pursue sustainable and low-carbon steel production, EAF technology will continue to evolve and contribute to the advancement of the steelmaking processes. EAFs offer more possibilities when compared with traditional blast furnaces. They can efficiently process a wide range of raw materials, including scrap steel, direct reduced iron (DRI), and hot metal, allowing for a more diverse feedstock. This enables steel producers to respond quickly to market demands and changing availability of raw materials. Crucially, they have a lower carbon footprint compared to blast furnaces and can be powered by renewable energy sources, further reducing their environmental impact and contributing to the transition towards green steelmaking. EAFs can serve as a platform for integrating emerging technologies and processes in steelmaking. As the industry progresses towards carbon neutral steel production, they can be modified and optimized to accommodate innovations such as direct electrolysis, carbon capture and storage, and other breakthrough technologies. This adaptability positions EAFs as a key component in the steel industry’s transition towards a more sustainable future.

FE: There is traditionally a lot of carbon in the steelmaking process, which is where the EAF comes in. It reduces the carbon content significantly. Customers are also testing their electrical furnaces with different configurations, beyond standard methods, to help achieve sustainability targets around the globe. Movement towards electric options vary depending on geographical region and legislative objectives set, but meeting sustainability targets is in the minds of industry operators and management teams.

What role does electromagnetic stirring technology play in the electric arc furnace?

ZM: Electromagnetic stirring (EMS) is not a new technology: it was first patented by ABB about 80 years ago, but it has evolved. Electromagnetic stirrers play a significant role in the operation of an EAF by improving the mixing and homogenization of the molten metal. The primary function is to induce fluid flow and agitation within the metal bath. By generating a magnetic field that interacts with the conductive molten metal, EMS promotes circulation to homogenize the temperature and composition and ensure more uniform steel. The stirring effect created by EMS enhances heat transfer within the molten metal. This improved heat transfer allows for faster melting of scrap steel and other raw materials in the EAF, leading to increased productivity and shorter processing times. It also aids in maintaining a consistent and uniform temperature within the furnace. The agitation provided by EMS facilitates chemical reactions between slag and metal while also improving the mixing of additives and alloying materials. By this way EMS enhances iron yield and solves the bottom skull problem.

The improved heat transfer and mixing effect of EMS, ensure the rapid homogenization of temperature and composition throughout the molten metal bath. This uniformity allows for more precise, efficient control of the steelmaking process, resulting in a more consistent and repeatable process. By fulfilling these roles, EMS contributes to the overall efficiency, quality, and consistency of steel production in an EAF. It helps steelmakers achieve better control of the EAF processes, improve efficiency and productivity. According to our research, typical benefits based on 160+ ArcSave electromagnetic stirrer installations worldwide include 5-7% increase in productivity, 3-5% reduction in energy consumption and related carbon emissions, up to 1% higher yield and lower use of alloys, lime and other process additions.

ArcSave electromagnetic stirring enables the production of more steel, faster and at lower financial and environmental cost.

How does using an electromagnetic stirrer benefit the production of steel regarding economics, efficiency, safety and the environment?

ZM: EMS helps reduce the environmental impact of steel production by improving energy efficiency and reducing carbon emissions. The enhanced mixing and heat transfer facilitated by EMS can lead to shorter processing times and lower energy consumption. Use of alloys, other process additions as well as electrodes and refractory materials is also reduced using EMS, further contributed to resource efficiency and lowering overall environmental impact. Additionally, when combined with the use of renewable energy sources, EMS contributes to the reduction of greenhouse gas emissions and helps achieve sustainable steel production. EAF-EMS has a measurable impact on furnace productivity. At Steel Dynamics, for example, productivity increased by 6%; at Outokumpu Stainless by 6-8%; and at SeAH, the increase was 5-7%. There is also an increase in yield, typically by about 1%. The agitation and improved heat transfer provided by EMS result in faster melting of scrap steel and other raw materials in the EAF. This leads to increased productivity, shorter processing times, and higher overall efficiency in steelmaking operations. EMS ensures the homogenization of temperature and composition throughout the molten metal bath. This uniformity allows for more precise control over the steelmaking process, resulting in consistent and high-quality steel products.

The faster melting and processing enabled by EMS contribute to higher production rates and increased throughput. This enhanced productivity can positively impact the economics of steel production by reducing costs per ton of steel produced. Steelmakers with EAF-EMS are able to maintain greater control of costs. Critically, energy costs are reduced, as power-on time is shorter and complete melting is achieved more efficiently. Energy consumption fell by 5% at Steel Dynamics, and by 3-4% at both Outokumpu Stainless and SeAH. These energy savings are inclusive of the energy used by the stirrer, which is roughly 2-3kWh per tonne of liquid steel. The use of EMS can improve safety in steelmaking operations. By enhancing the mixing of the molten metal, EMS reduces the likelihood of stratification, which can lead to localized overheating and potential accidents.

Electromagnetic stirring optimizes operation of the world's most productive EAF at Acciaieria Arvedi in Italy.

What was learnt from the implementation of an electromagnetic stirrer on Acciaieria Arvedi’s electric arc furnace in Italy?

ABB partnered with Tenova for their customer Acciaieria Arvedi in Cremona, Italy, to meet demand for higher productivity and increased electrical energy efficiency of the recently improved endless strip production (ESP) line. Acciaieria Arvedi placed an order in 2018 for a new 450- ton Tenova Consteel® electric arc furnace (EAF) to replace the existing 350-ton Consteel® EAF. ABB Metallurgy supported this project with the EAF-EMS application known as Consteerrer®, which was co-developed with Tenova.

ZM: The Acciaieria Arvedi furnace is a jumbo furnace. It is a type of furnace that did not exist before. We have learned much more about the benefits EMS can bring to these large furnaces, improving the process, productivity and also removing the pervasive bottom skull problem for steelmakers. As a part of the Acciaieria Arvedi project, we have learned that the stirring power has a clear effect on stirring efficiency. The higher the EMS power, the higher the stirring efficiency. Apart from improving furnace performance, Consteerrer® will improve the EAF process and reduce its carbon footprint. The key takeaways from the project are given below:

  • Temperature homogenization time is considerably longer at 447 seconds with 5% EMS and only 113 seconds with 100% EMS
  • The temperature gradient between the furnace bottom and the surface during arc power-on is reduced from 114o C with 5% of EMS power to 26oC with 100% EMS
  • The heat flux transferred to the scrap increases with increased EMS stirring power. The average heat flux transferred to the scrap with 100% EMS is 2.7 times higher than that with 5% EMS
  • Consteerrer® stirring improves heat and mass transfer in the EAF process and also reduces energy and electrode consumption, besides increasing productivity
  • The guaranteed KPIs with EMS are fully achieved in the new Consteel® furnace project

Hydrogen has become the main buzzword in the last few months, in industry. What is ABB’s position on hydrogen fuel?

FE: As a fuel, hydrogen is one possible solution and can be the right move for many industries. There are many challenges to its roll-out, including current high costs, transportation and infrastructure. ABB is part of the hydrogen business. We have a company in Sweden who we are collaborating with on a pilot project to see how hydrogen can then be further optimized, developed and scaled. One of the biggest challenges for hydrogen is making it scalable. Hydrogen doesn’t counter all the challenges we have, but a key benefit is that it helps with carbon neutrality. We can look forward to a future where hydrogen is very much part of the mix.

Electromagnetic stirrers already installed on electric arc furnaces

ABB has 165+ EAF-EMS technology installations globally including 149 first generation. According to ABB, steelmakers who have installed or will install ArcSave, the latest generation of this technology, representing all furnace types – carbon steel, stainless/specialist and Consteerer™ include:

  • Steel Dynamics Inc., Roanoke, USA, 2014, on a 90 tonne EAF for carbon steel production.
  • Outokumpu Stainless AB, Avesta, Sweden, 2014, on a 90 tonne EAF for stainless steel production.
  • POSCO, Pohang, South Korea, 2018, on a 95 tonne EAF for stainless steel production.
  • SeAH Changwon Integrated Special Steel, Chang-Won, South Korea, 2018, on a 70 tonne EAF for stainless steel and tooling steel production.
  • Yongfeng Steel, Shandong, China, 2019, on two 160 tonne Consteel™ furnaces for carbon steel production.
  • Böhler Edelstahl, Kapfenberg, Austria, 2020, on a 50 tonne EAF for special steel production.
  • Nippon Yakin, Kawasaki City, Japan, 2021, on a 70 tonne EAF for special steel production.

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