Tenova and ABB innovate to advance electric steelmaking

Collaboration is the buzzword of the decade. But when technology providers to the metals industry — ABB and Tenova — became alloyed, the hopes for sustainability of essential metals took a step forward. Think enhanced operation of electric arc furnaces.

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Zaeim Mehraban, Global Sales Manager, ABB Metallurgy, left, and Andrea Grasselli, Head of Proposals Department, Electric Arc and Ladle Furnaces, Tenova, right.
“Aside from the game-changing technology we’ve developed together, it’s a joy for me to collaborate with ABB,” says Andrea Grasselli, Head of the Proposals Department for electric arc furnaces (EAFs) and ladle furnaces (LFs) at Tenova, a leading developer and provider of sustainable solutions for the green transition of the metals industry.
“It was not so common to talk about sustainability at that time,” Grasselli says of steel manufacturing in 2017. But the two companies each had a proud history of constant technological development, “so we put on the table this heritage, to really squeeze the most from our experience, from working reference cases, and in that moment we started to talk about sustainability.”

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Tenova and ABB have collaborated on various customer projects over the past decade, but in 2017 the two companies sat down to bring two key technologies together. Their aims included to improve the efficiency and reliability of the melting process in large electric arc furnaces; and to boost EAF flexibility in relation to the variety of charge material that could be used while still producing the highest quality steel.

Says Grasselli, “We were convinced that our EAF Consteel® technology was good and pretty efficient, and the right technology to be sustainable in the steel market, but there was a need to consider other metallic charge materials, like pre-reduced iron, to substitute for scrap which is in limited supply.”

Melting moments

ABB’s electromagnetic stirrer (EMS) technology has been applied to hundreds of electric arc furnaces, to more efficiently mix the melt, reduce operating costs, and increase productivity, while minimizing formation of “skulls” — accumulations of hardened slag on the furnace bottom — which impede furnace efficiency and are hard to remove.

“We had a shared vision for improving sustainability of the metals industry through innovation,” says Zaeim Mehraban, ABB’s Global Sales Manager for Metallurgy.
Today, the tide of molten metal is turning towards steel produced without fossil fuels. For decades, electric arc furnaces (EAFs), the front runners for transforming the manufacture of steel to be powered by green electricity, have not been as productive as fossil-fuelled blast furnaces by a factor of about 15-20 percent. But this particular stumbling block to industry energy transition has been surmounted by Tenova and ABB’s bespoke solution, to the point where EAFs are almost at parity with the dominant method for primary steelmaking — the integrated blast furnace‑basic oxygen furnace (BF-BOF).

ABB has been developing electromagnetic stirrers for around 80 years. In 2011, it launched ArcSave®, a revolution in heat transfer within the EAF melt, which does its work with no physical contact with the furnace bottom. ArcSave® accelerated scrap melting rates, thereby reducing overall energy use and helped steelmakers obtain an exact tapping temperature for various steel grades, facilitating smooth tapping. The uniform melt delivered by ArcSave® also increased process safety and reliability, and reduced scrap cave-ins.
The technology collaboration combines the benefits of Tenova’s Consteel EAF’s continuous scrap charging and the efficiency gains of ABB’s electromagnetic stirrers in one high-performance solution

Leading the continuous charge

When ABB began collaborating with Tenova on an EMS designed to enhance the productivity of its Consteel® EAF, Consteel® had been proven in more than 75 installations worldwide. Its unique process of preheating and continuous charging into a liquid steel bath was far more efficient than conventional systems that used direct energy transfer to solids in conventional top-charging EAFs. Today, Consteel® EAFs have exceeded 100 units installed.

“We knew at the time the benefits of an electromagnetic stirrer on top-charging electrical furnaces,” says Grasselli, “and we wanted to apply that to our specific asymmetrical Consteel® furnace. We needed to solve the problem of scrap forming a cold area on one side of the Consteel® furnace and a hotspot on the opposite side, so our joint team decided to turn the ArcSave® EMS at 90 degrees to the furnace — to rapidly homogenize the cold and hot spots.”

The resulting Consteerrer® EMS also features a unique working profile to match that of the Consteel® technology. “The Consteel® furnace works throughout the process time in flat bath conditions with the liquid steel inside, so the Consteerrer® is engineered to operate throughout the power-on time,” explains Grasselli.

The integrated technologies reduce process times and energy consumption, which lowers costs and contributes to sustainability. Improved control over operational practices allows flexibility in terms of alternative charge mixes. Consteel® with Consteerrer® can optimize the use of direct reduced iron (DRI), hot briquetted iron (HBI) and beach iron (low-purity pig iron) as available, and as needed.

A productive match

Italy’s Acciaieria Arvedi became the first steelmaker to install the fruits of the Tenova-ABB collaboration. In 2018, it ordered a 450 tonne capacity, 9.1m diameter, Tenova Consteel® EAF equipped with Consteerrer® EMS for its site in Cremona.

Final acceptance of the system was confirmed in 2022, along with consistent process improvements on previous technologies. These include: an 18 degrees Celsius lower tapping temperature and a 3.6 percent reduction in electrical energy consumption, which together deliver a 38,000-tonne annual reduction in CO₂ emissions at the plant. EAF productivity has increased by 5 percent and final oxygen content in the EAF steel has decreased by 17 percent.

Today’s most productive blast furnaces can achieve a rate of 450 tonnes of steel per hour. The productivity of Arvedi’s installation is around 415 tonnes per hour. However, Grasselli says Tenova furnaces currently under development will exceed this value. “We are really close to blast furnace productivity,” he says, “and we could not reach this level without the Consteerrer® — it would not be possible.” Mehraban adds that, “Five years ago, a 200 tonne EAF was considered big — productive capacity has substantially grown in recent times.”
Electromagnetic stirring accelerates scrap melting rates, thereby reducing overall energy use and helps steelmakers obtain an exact tapping temperature for various steel grades, facilitating smooth EAF tapping.

The safety imperative

He also emphasizes that EMS enhances the safety of steelmaking. “Because the equipment provides process control — control of the bath, the temperature and homogeneity — the process is more reliable, and therefore safer,” says Mehraban. Being non-contact, meaning it has no physical contact with the furnace or melt, EMS, also eliminates the need for competing technologies, such as bottom gas stirring, in which jets of gasses such as argon are used to agitate the melt via holes in the bottom of the furnace. “Every hole in the furnace presents a risk, and although the probability of seals failing is very low, the consequences are too high to ignore. Bigger furnaces may need up to seven additional jet-injection holes, and many steelmakers have deemed the risks too great.”

Tenaris is a sister company of Tenova, under the Techint Group, and is proud to be one of the safest steelmaking companies in the world. In 2023 it ordered its first Consteel® EAF, also equipped with Consteerrer® for its Campana plant in Argentina, for reasons of both safety and quality. “They produce seamless pipe, which requires extremely high quality steel; it is one of the most demanding steel grades to produce,” explains Grasselli. “And they have to produce it using varying metallic charge — a lot of HBI and likely future DRI input — so Consteerrer® will help boost their flexibility.”

ABB and Tenova’s integrated technology package answers many needs of modern steelmakers.

Ternium is another Techint Group company and is building a state-of-the-art new steel mill in Pesquería, Mexico. Here the pairing is one of the main technologies of a US$2.2 billion development, which will have production capacity of 2.6 million tonnes per annum of top-quality steel for the e-mobility automotive sector. Consteerrer® will deliver efficiencies that help improve the sustainability of the plant, and lower operating costs.
A new Consteel® EAF  equipped with Consteerrer® electromagnetic stirring will provide Tenaris with the operational flexibility needed to produce high-quality steel for seamless pipes from varying metallic charge. Photo: Tenaris.

The undeniable competitive edges

The Turkish steel market is one of the most aggressively competitive in the world, and Hasçelik’s plant in Osmaniye needs a new production line to produce both high-quality steel for automotive markets, and commercial products such as rebar. Flexibility is key, with the reduction of operating expense (OpEx) for commercial steel a close second imperative. Hascelik will soon install a 60-tonne Consteel® EAF, with EMS, a ladle furnace and a twin vacuum degasser. “In this case Consteerrer® enables both flexibility and a reduction of around 15 kilowatt hours in the energy consumption, allowing Hasçelik to have one of the most sustainable and efficient EAFs in Turkey,” says Grasselli.

POSCO, in South Korea, provides a different use case. One of the biggest steelmakers in the world, POSCO produces more than 40 million tonnes of steel each year, based 95 percent on blast furnaces and converters. It decided to advance its transition to sustainable technologies and opened a tender for an EAF, which Tenova and ABB won based on their integrated technology.

Says Mehraban, “POSCO is a very knowledgeable steelmaker and a repeat customer of ABB. They already understood the benefits of ArcSave® technology, since we had provided a stirrer for a top-charging EAF back in 2015-16. Making this new investment in a very big furnace for high productivity, they knew what they wanted.”

More barriers to overcome

There remain other challenges to widespread adoption of more sustainable EAF technology — such as local availability of sufficient renewably sourced electricity, and government policies that incentivize the large investment in swapping what may still be high-performing fossil-fuelled furnaces and processes for EAFs. But Mehraban says the industry agrees that transition is inevitable, with improved sustainability now the primary driver for steelmakers to switch technologies; and productivity, flexibility, safety and cost reductions are all important decision-making factors.

When asked what they are most proud of in the ABB-Tenova collaboration, Mehraban says, “We each have a very specific value proposition.” That is, Tenova’s Consteel®, unlike conventional top-charge EAFs, offers unparalleled efficiency via its unique process in which the melt is preheated and charges continuously into a liquid steel bath; and the Consteerrer®, a bespoke development of ABB’s ArcSave technology, provides homogeneous temperature distribution within the EAF melt, accelerated scrap melt rates, reducing energy use and facilitating smooth tapping without delays. “We have worked passionately together to bring that combined value to our customers.”

Grasselli agrees, “The way we talk with one another as colleagues makes me really happy whenever I have the opportunity to interact with our counterparts in Sweden.”

“Our shared passion for innovation and belief in the importance of sustainability is what brought ABB and Tenova together but when I look back on my career it will be the team spirit of the people I remember most. I’m excited to see what more we can do together to increase efficiency and reduce the carbon footprint of steel production,“ says Mehraban.

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