Danieli's Gianpietro Benedetti on the future of steelmaking

By IM Staff
Published: Wednesday, 16 February 2022

Danieli Group chairman Gianpietro Benedetti has six decades of global experience in steel production and innovative technologies for the industry. He discussed with Richard Barrett trends in steelmaking, green steel production and some of the key technologies available to achieve them.

 Gianpietro Benedetti  

Speaking to Metal Market Magazine in early December 2021, Danieli Group chairman Gianpietro Benedetti started by observing that: "At this very moment, everyone in steelmaking is happy." High steel prices and demand in the wake of the Covid-19 pandemic had made most steel producers highly profitable. "All the steelmakers now, I don’t know what they are going to do with all their money!"

Steelmakers have achieved the equivalent of €400 ($453) per tonne in earnings before interest, taxes, depreciation and amortization (Ebitda) for steel strip, he said, resulting in recent quarterly total Ebitda for some major producers running into hundreds of millions, and sometimes billions, of dollars. "What are you going to do – buy Buckingham Palace? I don’t know!" he laughed.

While he often shows his sense of humor, Benedetti is serious about the profitability of Danieli and the wellbeing of its international workforce of thousands of people. The Buttrio-headquartered international metallurgical plantmaker and steel producer, near Udine in northern Italy, has expanded dramatically through acquisitions and organic growth during the decades he has held the most senior roles at the company.

Very few people in the global steel industry have built the international breadth and depth of experience he has acquired over the 60 years since he began work with the company in 1961. Starting as a design engineer, he soon became a project engineer and then plant start-up engineer, and progressed to become Danieli Group sales director in 1977. He has been chairman of the Danieli Group for more than 18 years.

With his personal engineering background and many patents to his name, Benedetti speaks with ease about the details of the company’s many innovations, but he also has the business acumen always to explain the commercial benefits that the company’s technologies will bring to the steelmakers and metal producers deploying them.

He prefers to speak about the company, its business and its technologies than about himself, but he is open about his passion for commissioning sculpture and art, on view both inside and outside the complex of buildings at Danieli’s home base.

In the little spare time his role allows him, he has occasionally turned to painting a little himself, and he has also confirmed his enjoyment of driving and his appreciation of automotive design in the past. Artistic designs to express concepts sit very comfortably beside the precision of engineering drawings and computer models in Benedetti’s world.

Over the years, he and his contemporary Cecilia Danieli, who managed the financial and the administration side of the business from the year of his appointment as group sales director and who later became managing director before sadly passing away 22 years later in her mid-50s, have encouraged investment in education, whether for the children of company employees, students in the region, or through the professional training of staff across the group’s many international locations.

Near its headquarters, the company built a nursery school and kindergarten in Italy, named after Cecilia, and has developed its own academy to recruit students in Italy and to support the education and development of staff globally. In addition to a global network of sales and distribution offices, Danieli has invested in major workshops in Thailand, China and India, complementing the company’s major workshops in Buttrio.

Business trends

Since Danieli is involved in steelmaking itself through its business ABS, which has also very successfully served as a test-bed for some of the metallurgical plantmaking division’s innovative technologies over the years, Benedetti is also ready to discuss steel market conditions in addition to technological trends, as well as the essential links between them. Green steelmaking technologies designed to fulfil the steel industry’s need to reduce carbon emissions are high on his list of priorities.

The Danieli Group’s own results are of course strongly influenced by international steel market trends. At €2.8 billion ($3.17 billion), group revenues for the financial year ending June 30, 2021, were stable from the previous year, with lower sales in the plantmaking segment of its operations offset by increasing sales in its steelmaking segment.

At €1,847.8 million, plantmaking revenues were 14% lower than the previous financial year, but steelmaking revenues were 42% higher at €938.5 million. Steelmaking products sold in the period (ABS Group) reached about 1,150,000 tonnes. The group order book of €3,534 million on June 30, 2021, was substantially up from €2,936 million one year earlier.

Danieli Group Ebitda of €250.2 million was up by 33% from €187.7 million for the previous financial year. "The cash position, which remains strong and solid at €1,002.0 million, has allowed the company to deal with the delays and market imbalances caused by the pandemic," the company noted in a press release issued on September 27, 2021.

In his discussion with Metal Market Magazine, Benedetti observed that long-term volatility in the steel market repeats every 10-12 years. "It is difficult to say exactly, but something like that," he remarked. "But we know that maybe in 2022 or 2023, the market will become normal and we will have a move back down."

Thinking about the medium term of the next 2-3 years, he said there are two main factors that will characterize the world steel industry and markets. "One is carbon dioxide – that is not an opinion, it is a fact – and the other is global commerce," he said. "Will it stay open as today, will it become regional, or will it become influenced by the big areas, by which I mean [the United States] and China?"

He noted that Europe is already programmed to reduce carbon dioxide emissions and that most probably China and India will follow. "But we cannot ask China and India to reduce carbon dioxide emissions while the average level of life [individual wealth and quality of life] is still very low," he added.

He said that Danieli’s Chinese customers also want to reduce carbon emissions and are looking at what to do, but he thinks they will probably take more years to do so than plants in Europe.

He reiterated that global market conditions will have a big influence. "It will be necessary to have some kind of duty, or some kind of control on imported steel. As we are doing with carbon dioxide – with that we are controlling everything," he said, including measures such as carbon border taxes. "Most probably, something similar will be applied to the steel market," he added.

He stressed that in Europe the total cost per tonne in future will comprise capex per tonne, opex per tonne and carbon-dioxide tax per tone. "That will be the total cost," he said, "and this is the reason why people are forced to go with carbon dioxide reduction."

Hydrogen as an answer

Benedetti acknowledged that reducing iron ore to iron by using hydrogen is part of the solution. "If we talk more generally about carbon dioxide emissions, everyone is talking about hydrogen, but in my opinion there is a little problem on this," he said.

He pointed out that today about 30-35% of carbon dioxide emissions come from energy, electricity and heat generation. Industry accounts for about 23-24%, depending on location; transportation generates around 15%; and agriculture 24%. Buildings also contribute about 5-7%, depending on their location.

"In all of this, our core steel industry accounts for about 5% directly, plus 12-15% together with indirect emissions, which is mainly electricity," he added, noting that in this scenario everybody in Europe is thinking about how to reduce carbon dioxide emissions.

Globally, 65-70% of steel is produced with blast furnaces. In Europe, about 60-65% comes through the blast furnace route. "By comparison with the US, this is quite high, because their producers are quite electric-arc furnace (EAF) and mini-mill oriented," Benedetti said.

"So, the blast furnace is the main target and everyone is discussing what to do. It’s quite impossible to do it at once of course. It will take several different steps," he explained. "There is a step to improve the efficiency, to collect the gas and inject oxygen into the blast furnace to reduce 15% of the carbon dioxide. The second step is to have one or two blast furnaces and one EAF."

He acknowledged that another straightforward way to reduce carbon dioxide emissions from the blast furnace route is to increase the amount of scrap used in the converter (to as much as 30%), but he added that will make life difficult for electric steelmakers when competition increases for supplies of scrap.

The way forward for any given steelworks depends heavily on its location. For example, in Danieli’s home nation of Italy, which produces about 90% of its steel through electric steelmaking, Benedetti said that finding a source of diret-reduction iron (DRI) that can be produced where gas is cheap is another option. North Africa and the Middle East are locations with the natural gas needed. "The solution, from the technical sense, is raw material consumption in the form of DRI to buffer the extra use of scrap," he explained.

Integrated steelworks, based on BF production, can replace BFs with EAFs in stages (see table). "That means DRI, which will cut more than half of the carbon dioxide emissions, by 60-80%," Benedetti said.

"You can make a mix for integrated works. That means pig iron and DRI go in a special furnace. You make a mix, and you produce pig iron, and you reconnect with the existing meltshop – that will be the intermediate phase," he explained. "And the final phase is all-DRI and the electric furnace with hot charging, which will reduce the carbon dioxide emissions by as much as 85%."

Hydrogen fits into that picture as a replacement for the natural gas used in DRI production modules. The "little problem" that Benedetti highlighted is the amount of energy needed to generate hydrogen and the sources of the electricity required to generate it, with the latter factor also being an issue for the growth in electric vehicle usage.

"To make hydrogen today, for 1kg you need 50-60kWh. This means you may need some kind of new technology to provide it – some kind of energy breakthrough," he said.

"Here we go to the ridiculous – like electricity mobility," he added, referring to Italy as an example. While acknowledging that, for a given town, the wide use of electric cars is good for its own population and their local environment, he said it makes less sense at a national level: "If we talk generally," he said, "why use an electric car when 70-75% of the electricity in the country is produced with coal, oil and gas? Come on!"

He thinks that diversity of energy supply will be essential. "I know that in some countries it is not very politically correct," he said, "but in my opinion the only solution to go green with hydrogen is nuclear power in addition to the other forms of sustainable energy such as wind, solar and hydropower in locations where that is possible."

He noted that the latter renewable forms of power generation account for about 30% of electricity generation in Italy at present, and that they could possibly be increased to 45%, or as much as possible. "But the rest, most probably, will be nuclear, whether fourth- or fifth-generation plants are built. The production of green hydrogen will require a lot of energy for the time being," he said.

While Danieli itself does not supply the electrolytic technology needed to generate hydrogen in volume, Benedetti noted that: "We are lucky with Energiron plants that we have DRI technology [in collaboration with Tenova] that is naturally prepared to utilize as much as 85% of hydrogen: from zero to 85%, so we don’t need to do anything. It is done. The only thing is: where is the hydrogen."

He said that Danieli is talking with "everybody who is planning to produce [by using] hydrogen," mentioning the examples of the Hybrit project in Sweden and Voestalpine’s plans in Austria, but he stressed again the importance of energy supply.

"In the meantime, we are in a transition with gas, where available at a reasonable cost, which is intermediate because you are cutting down by 60-65% compared with a blast furnace," he said.

DUE (Danieli Universal Endless) plant technology for flat products has already been applied successfully for QSP (Quality Strip Production)  

Making a transition

Danieli has partnered with several major international steelmakers to identify the best means for them to reduce carbon emissions, with Metinvest being one of the most recent to agree on such collaboration.

"The issue is always the same: how to grow, but also how to reduce carbon dioxide emissions. You cannot do it in one day, so you must plan. First of all, you can reduce emissions by the blast furnace by at least 20%," Benedetti said.

"Normally, the idea is that if you have three BFs, you start to close one and install a Danieli Digimelter," he explained. "We don’t talk any more about an EAF, which is the past – that is like driving a car and constantly looking in the rear-view mirror!

"You then have the mixer with the direct-reduction. You then have intermediate pig iron in a furnace and you put it into the converter. The final part is to close one part of the converter and to go directly to the electrical furnace and two casters," he said.

"You cannot generalize the best system," he added. "You must make a tailor-made study in relation to the general layout of the existing plant. You simply cannot go in and destroy everything and stop production for months. So, generally speaking, you have to do everything in steps. And the final step, of course, will be direct-reduction with hydrogen."

He pointed to what he sees as the folly of exporting scrap from, but importing rebar into, the UK, but he also noted that a target of the UK government is to produce hydrogen with wind power.

"In this case," he said, "when you succeed in doing it, the [best] idea is hydrogen-based DRI production, hot-charging into an EAF or Digimelter at 600 deg C, so saving energy. So, EAF, ladle furnace, caster, direct rolling; perfect, then you are close to green steel – that means close to 90% carbon dioxide reduction or net-zero. Hydrogen, DRI, Digimelter – that is the future, in our opinion."

More green technologies

Benedetti elaborated that using hydrogen is certainly not the only means of reducing the steel industry’s carbon dioxide emissions.

"Within steel plants, we are strong believers in direct rolling," he said. "Our main target today – and we are already doing it – is to eliminate the reheating furnace."

That is a "great way to reduce carbon dioxide emissions," he pointed out, because reheating furnaces consume energy to heat semi-finished steel products, such as slab and billet, from the ambient temperature of a stockyard to the temperatures needed to pass them through rolling mills to make finished products.

Progress has also been made to improve the efficiency of, and reduce emissions from, EAFs. "For the EAF, we went to digitalization – the Digimelter," Benedetti said. "We are already building the first, totally new EAF, for CMC [Commercial Metals] in the United States. This Digimelter will have very close to net-zero emissions. We just inject carbon into the furnace to produce the required [grade of] steel."

He added that, in the US, Danieli is trialling the use of recycled plastics to provide the carbon needed. "The first experiment after six months has shown that we are able to reduce 30% of the carbon dioxide emissions in the EAF because of that," he said. "This, plus the closed furnace – we are designing a totally enclosed Digimelter – will bring us 55% reduction of carbon dioxide emissions in the Digimelter, the electric meltshop."

In summary, he said: "Those are direct-reductions in carbon dioxide emissions: hydrogen, DRI, Digimelter and direct rolling. By doing that globally, from the raw material down to the finished products, we will [eliminate], by comparison with an integrated plant, 90-95% of the carbon dioxide emissions."

Solar power

The direct supply of solar power to steelworks in climates that support it is gaining traction. Fata, which is part of the Danieli group, specializes in solar energy.

Benedetti said that the Digimelter can utilize recoverable energy at any moment and at any percentage, so it is amenable to solar power supply.

"We already have a successful operation, which started up just six months ago," Benedetti said. "We have a solar field with movable solar panels that concentrate the sun’s heat on pipes containing special salts which heat up and provide energy to generate steam and power, also providing energy by night or when poor daytime weather obscures the sun, storing enough heat for up to 24-hours of energy supply."

Benedetti said that the latest plant Danieli installed in California with CMC receives solar power. "Also in Mesa, Arizona, where we are installing in one year, this company is also acquiring land to install a solar power supply," he added.

Solar panels will increase energy efficiency by 20%, he said, as has been seen through some good results in the US. "With 60% efficiency, solar power will really become a reasonable and economical source of energy," he added.

Endless rolling explained

Endless rolling – continuously feeding steel through a mill for long- or flat-products – has the advantage of avoiding material wastage at the head and tail end of a coil produced from a single billet or slab and, when achieved by feeding the steel directly from the caster through the mill, also saves energy.

Benedetti pointed out that to achieve direct rolling in endless mode requires a high-speed, high-productivity caster. Danieli has developed its Octocaster technology for long products and its Dysencaster technology for flat products.

"We have succeeded for long products. We are already producing 700,000 tpy with one strand. The target is to reach 1 million tpy," he said. The casting speed is up to 10 meters per minute: "It is like a McLaren racing car!"

Such casters installed for CMC and Nucor in the US are already achieving casting speeds of 7.5-8 meters per minute, with peaks of 9 meters per minute, Benedetti said.

In January 2021, Danieli announced that the Bashundhara Group in Bangladesh had ordered a MIDA endless-casting rolling mill – the latest version of the plantmaker’s regional micro-mill – to produce more than 1 million tpy of rebar and wire rod for the local market.

Scrap will be continuously melted by a 100-tonne Digimelter running at 150 tonnes per hour. The single-strand caster will use an Octocaster mould to deliver endless billet to the mill at casting speeds of more than 7 meters per minute. The mill is expected to start-up by early 2023.

DUE (Danieli Universal Endless) plant technology for flat products has already been applied successfully at the QSP (Quality Strip Production) DUE plant at Shougang Jingtang, China, which was the first plant of this new generation to obtain a final acceptance certificate.

"In flat products, we target production of as much as 3.5-3.8 million tpy with one strand," Benedetti said. "The challenge, after we started the plant for Shougang Jingtang in China, was we found that we can achieve any steel quality through direct rolling from 1mm thickness upward, but no exposed parts."

He added that Danieli is challenging that now. "We are already engineering a system that will allow us to produce exposed parts from direct rolling. When we succeed in doing so, traditional hot-strip mills - 'bye bye, auf wiedersehen, arrivaderci!’."

That said, he acknowledged that it usually takes years to develop an innovative idea to achieve its commercial application. "Once you have formed an idea, you have to convince other people to do it. You need time. You need to build a prototype, to modify the prototype, and the ideas are born after 6-8 years," he said.

"When you are successful, you get this baby, you install it in an industrial plant somewhere, willing to introduce a visionary concept – there are not so many because some are much more general managers than engineers, and they worry more about the balance sheets and cost, so they are less willing to escalate the limits [or push the boundaries]," he explained.

"If the idea is successful at an industrial scale, you need 10 years to convince the rest of the industry!" he said, laughing out loud.

He said that endless rolling is a good example, which Danieli developed in collaboration with CMC in the US: "Everyone was laughing [at the beginning of developing the idea], but now, after 10 years of it working successfully, everybody wants it!"

Danieli notes that the CMC Steel Arizona 2 MIDA Hybrid mini-mill for long products is the first to produce merchant bars in endless-casting rolling mode.

For exposed flat-rolled steel, the speed of the caster and the level of residual tramp elements from scrap in the steel make a difference. For this reason, Danieli has developed a system that has the capability to closely control solidifying steel in the mould, which can keep the surface practically flat. "We also incorporate the mould powders, and internally you have a good thermal distribution of the temperature, and this lets you keep the casting at high speed," Benedetti said.

Mills of the future

Benedetti explained that some types of steel cannot be cast at high speed for general metallurgical reasons. "For those few qualities, we need to decrease the speed, but then you cannot go endless," he said. "For this reason, our plant for flat and long products, Danieli Universal Endless, can operate endless, coil-to-coil or billet-to-billet for semi-endless."

He explained that when, for metallurgical reasons, it is not possible to cast and roll at high speed – typically for 20% of the mill’s production – the mill can work from billet-to-billet, or coil-to-coil, or semi-endless, rolling three coils per time and 10km of long products per time. "This is why we call it universal endless," he said.

He swiftly dismissed a thought that putting very high volumes of steel through a single caster would have implications for the durability of equipment put under such a heavy load. "No - don’t forget that we have spent 15 years working on that. Today, the high-speed caster gives you practically the same operational duties and maintenance as a normal caster, in terms of materials, electricity etc," he said. "It is fully automatic, we are changing the water flow and we have all the information from the mould etc. It is a digital caster."

The digitalization of plants is an established technology, but it continues to evolve and has been highlighted by some equipment suppliers as a virtue in having enabled them to help to start-up plants at clients’ sites remotely during the Covid-19 pandemic.

Benedetti, however, made light of that capability and preferred to focus on its other benefits. "Forget digitalization because of Covid-19. It is required for many other reasons," he said.

The first he highlighted is the difficulty of finding highly qualified people willing to work anti-social hours, including night-shifts and weekends, adding that, in Europe at least, it is even harder to find new young recruits to work such shifts.

He said it is easier to have an 8-hour day during daytime weekday hours, in which everything is prepared, including tool changes and guides to check that everything is set to run automatically overnight. "Our automation, big data and artificial intelligence [AI] will cover the absence of highly skilled and experienced people [during anti-social shift-hours]. We have plans that mean zero-people on the floor," he added.

"The second reason – no less important – is safety," he said.

He gave the example of the new 1,000-meter-long quality wire rod mill (QWRM) installed at Danieli’s own steel subsidiary business ABS near Danieli HQ in northern Italy - "with very sophisticated central mechanical control, water, temperature, cooling air etc. in relation to the steel quality."

He recalled that a common phrase used in the steel industry now is 'light and strong’, but he noted that producing such products can cost a lot.

"You can make light and strong with efficient guaranteed thermo-mechanical control," he said. "If you came to see the QWR plant now – and the same with flat rolling – you will see zero men on the floor. You must open a security door to enter the mill: the mill is totally enclosed – like a box. If men need to go in, you have to stop the plant, otherwise the door will not open."

He said that "automation" is the wrong word now. "With today’s systems, you have big data and artificial intelligence, but what does this mean?" The answer is that the mill is designed to work autonomously to make the right products on demand.

"Because when you do quality - 50, 60, 100 tonnes - you cannot make storage. Because normally, when you provide storage for A, B, C qualities, [customers] will order D, E, F and then you need enormous storage and it is no good," he said.

So the aim is to have a high utilization factor, but nevertheless have the capability to change rolling dimensions three, four or five times per shift and steel grade perhaps 10 times per shift. "But if you do it," he said, "you must be sure that the first bar of the new steel grade or the new dimension is perfect. You cannot change and wait half-an-hour to produce the first bar because it’s initially out of dimension, quality, etc."

 Summary table of technological combinations to decrease CO2 emissions by comparison with the conventional integrated steelmaking process

To achieve that means having sensors throughout the system to record quality and plant settings. "You memorize all this data, and when an order for this quality from that customer for that product comes in, it means a steel grade [can be produced] for a well-defined utilization," Benedetti said.

The new Danieli QWR mill at ABS produces 500,000 tpy of special steel wire rod in 5.0-25mm diameter at finishing speeds of up to 475 km per hour. The highly automated intelligent plant design with swift automated equipment changeovers needs only 14 operators for each shift. Danieli reports that the plant produces special steel quality coils with good dimensional tolerances and minimized surface defects, both under 0.1mm, and a grain size of 9 or finer, as per ASTM standards.

With a speed of 132.4 meters per second, equal to 476.64 km per hour, Danieli claimed a new world speed record for rolling 5.5mm-diameter wire rod in September 2021.

Benedetti added that steel grade is one thing, but high utilization is another.

"Sometimes, high utilization means different mechanical characteristics with the same steel grade. So, with big data I have the possibility to set up the mill automatically for the best quality for the best customer," he said. "Of course, the mill is not going on [completely] automatically, the operator is still in his control room with the data needed to make a particular product, but he then pushes the button to let the plant go. This, in our opinion, is the future."

Key projects

Danieli delivers hundreds of plant orders from relatively small upgrades to complete turnkey projects each year. Benedetti identified some key current projects that he sees as particularly significant and illustrative of the technology trends he discussed with Metal Market Magazine.

In Russia, for example, Danieli is installing direct-reduction with hydrogen for OMK to enable hot charging into an EAF. It comprises a 2.5-million tpy direct-reduction plant and 1.2-million tpy EAF and LF to melt for the production of hot strip and seamless pipe and for the rail complex at Vyksa in Russia.

For Nucor Gallatin in Gent, Kentucky in the US, the plantmaker is building a new generation of medium-slab caster. "It’s not thin, because we are going for 140mm thick slab," Benedetti said. With a new EAF meltshop, the new 3-million tpy caster and a hot-strip mill upgrade will expand production of AHSS and API grades.

In China, having successfully started up one year ago a QSP DUE mill for hot-rolled strip for Shougang Jingtang, Danieli has recently received an order from Yunnan Yuxi Yukun Iron & Steel Group for a new strip production plant to produce 4.6 million tpy with a Dysencaster medium-slab caster producing 110/120mm thick slabs after soft reduction to feed the 3+5 stands of the hot strip mill.

The caster will have two casting strands. It will operate in endless and semi-endless modes on strand No1, or coil-to-coil mode on strands Nos1 and 2, with a swivel furnace connecting strand No2 with the mill.

The new plant will produce strip in thickness from 0.8mm to 25.4mm in any steel grade apart from automotive exposed material. It is scheduled to start up in the second half of 2023.

That it is the third Quality Strip Production (QSP) plant, because Danieli is engineering another for Evraz in Russia. Benedetti said that client had ordered a DUE medium-slab caster to produce a wide range of widths.

"Another order that in my opinion is a milestone is the order that we received [in November] from Algoma Steel in Canada, where, after two years of discussion, they have ordered from us two Digimelters (150 tonnes) to substitute for a blast furnace. It is really the first industrial substitution of the blast furnace, because before that they have been relatively small test facilities… This is really substitution," he stressed.

The Canadian government is investing C$5 billion ($3.9 billion) to decrease carbon dioxide emissions. "It is a very strong government vision and Algoma is getting part of that financing to shut down the blast furnaces," Benedetti said.

"As I have said, the core idea is that in future the cost of steel is the sum of capex per tonne, opex per tonne and carbon dioxide tax per tonne," he said. "If you are smart, you have the idea to decrease carbon dioxide, but also to decrease opex. Otherwise, it is not sustainable. So, you must decrease carbon dioxide, but also decrease opex – less consumption, less energy, less water, less transportation – all those things. The new total cost must be competitive with an existing plant, so people will be encouraged to invest."

The Danieli Digimelter

 The Digimelter® is designed for minimal opex, low environmental impact and high flexibility for raw materials  

The Digimelter® is designed for minimal opex, low environmental impact and high flexibility for raw materials  

Danieli developed and patented the Digimelter®, which it describes as an intelligent melting unit, comprising a combination of power, intelligence and environmentally friendly equipment to achieve 15,000 heats per year with minimal opex, low environmental impact and high flexibility for raw materials.

Power is generated by the Danieli Q-One® digital power-feeding system, which the plantmaker says overcomes the limitations of traditional transformers. Q-One digitally controls both current and voltage, independently for each electrode, providing high power factor and low disturbances.

The plantmaker’s Q-Melt™ intelligent automation minimizes opex and provides consistent operation, notes Danieli, controlling automatically and in real time each chemical and electrical working parameter to achieve the best performance.

Flexibility on raw materials is provided by a Zerobucket system. In combination with a new sealed furnace design, it is said to reduce by half the direct carbon dioxide footprint and by 25% the overall carbon emissions by comparison with conventional EAFs. Danieli notes that electrical energy consumption is reduced by 5% and electrode consumption by 15%.

The Digimelter 'Eco-Pro’ airtight design was conceived to minimize the emissions of pollutants and their carbon dioxide equivalent. The furnace is always kept sealed, deploying an automatic slag door and improved sealing between the furnace and the conveyor. Q-Melt is designed to minimize oxygen and carbon injection, to ensure the most efficient melting at the lowest carbon dioxide footprint.

Danieli reports that, compared with a conventional EAF with the same charge mix, Digimelter Eco-Pro reduces the carbon dioxide direct emissions (Scope 1) by more than 50% and overall carbon dioxide emissions (Scope 2) by 25%.

Algoma Steel has chosen the Digimelter to make a full transition from integrated to electrical steelmaking, planning to make a 70% carbon emission reduction by converting fully from BF- to EAF-based steelmaking.

To be installed at Algoma Steel in Sault Ste. Marie, Ontario, Canada, the new green steel shop has design capacity for 3.7 million tpy of liquid steel, with two 250-tonne EAFs at its core, powered by two Q-One digital power systems with rated capacity of more than 190 MVA each.

The new Digimelter will produce high-quality liquid steel from recycled steel scrap, with the option of the direct addition of a wide range of other iron inputs. The Digimelter allows direct use of renewable energy for electric steelmaking and the new plant will make extensive use of mechatronic technologies.

Engineered enclosures will encapsulate the two furnaces to minimize noise and emissions. Q-Melt will be used to maximize energy efficiency. Two new off-gas treatment plants including baghouses and a dedicated recirculating water treatment plant will combine to provide emission control and filtration and to conserve water.

The investment will include a Danieli automated scrapyard with automatic cranes, scrap visual recognition, and automatic scrap sorting and charging. A new Danieli twin-tank vacuum degasser with oxygen-blowing facility will also be added to the process route to deliver advanced grades of steel and further enhance steel cleanliness and final product quality.

The new steelmaking facility is expected to be put into operation in early 2024.

High-speed casters

As Gianpietro Benedetti said, a single-strand, high-speed continuous casting machine is the core of the Danieli endless casting and rolling process.

Long products

Equipped with patented FastCast Cube (FCC) mould oscillator, Eco-Power Mould® copper tube and a new octagonal section, Octocaster® technology produces quality endless billets at speeds up to 10 meters per minute, making it possible to reach productivities as high as 1.5 million tpy with a single casting strand. The Octocaster is designed to take advantage of the best, different, properties of casting conventional round or square billets.

Danieli says this performance is achieved through technologies the company has developed over 20 years of endless casting and rolling experience to allow continuous and stable production.

The octagon-shaped mould and the Q-Cool solidification model – part of the Danieli Automation process control package – are the latest developments. Combined, these patented technological solutions make it possible to produce at high speed and production rates, minimizing bulging phenomena that arise when the solidified shell is so thin that it can bend outward due to ferrostatic pressure.

Conventional square-shaped billets are affected by bulging deformation, making it necessary to install roll sections along the caster curve to contain the deformation. Octagonal and round billets do not require this, because the ferrostatic pressure is better distributed and the deformation does not show, the plantmaker explains.

Danieli says that FCC achieves an oscillation range 50% wider than a conventional oscillator design and an acceleration of up to 6 meters per second squared. FCC is also said to operate with high precision and reliability, decreasing maintenance activities and costs compared with conventional oscillators.

The Eco-Power Mould provides improved thermal exchange and temperature distribution through a new patented channel design. New manufacturing methods increase copper tube rigidity for a higher contact stability with the product. Owing to a longer lifetime, the opex of the Eco-Power Mould is comparable to that of conventional copper tubes, according to Danieli.

A software model, Q-Cool monitors and dynamically controls the cooling parameters and product solidification. Danieli says this allows process stability under any operating conditions, resulting in smooth production sequences and a higher product quality.

The plantmaker also says that its automation model is proven to offer highly accurate and fast calculation of process parameters, over slabs, blooms and billets, in different steel grades. Off-line functions allow metallurgists to test new casting practices virtually, simulating relevant effects on billets.

Product guiding along the curve (copper tube, foot rolls and cooling zones) is a basic requirement for process stability. Owing to the eight flat sides of an octagon, its characteristics for this need are enhanced by comparison with both round and square billets.

Solidification starts inside the copper tube billet shell. Constant contact between copper tube and product is requireed for the growth of a uniform shell. Corners improve this characteristic, which is maximized by the octagonal section and its eight corners. While round sections show the worst attitude in the latter respect, on temperature distribution, for which uniformity allows more stable and higher quality rolling, they are the best shape. But the octagon is very close in its performance for this characteristic.

A high-speed continuous casting machine is the core of the endless casting and rolling process  

Flat products

For casting flat products, Danieli has its Dysencaster® technology, designed to produce as much as 4.5 million tpy on a single strand. The plantmaker notes that its Danieli QSP and QSP DUE thin-slab caster technology is now mature for production of automotive steel grades.

Danieli explains that owing to greater slab thickness and its new, proprietary electromagnetic brake technology allowing a significant size reduction of the submerged entry nozzle (SEN), it is now possible to work with a full-flat copper plate for a superior surface quality, including peritectic grades.

A calcium-free steel is mandatory for high-quality automotive grades, exposed and non-exposed, Danieli notes. This process requires the possibility to inject argon to the SEN and the changing of the SEN itself during casting, to counteract the occurrence of clogging.

The smaller SEN dimensions and the electromagnetic brake allow a nozzle quick change, as per a traditional caster. Handling of the SEN via a robot guarantees accuracy and repeatability of its position and safe operation. The powerful electromagnetic brake is able to manage the flow pattern in the mould without suffering disturbances from argon blowing.

This combination of technologies makes it possible to cast calcium-free steel without limitations, Danieli explains, satisfying the requirements of the automotive industry.

Danieli’s Octocaster® technology produces quality endless billets at speeds up to 10 metres per minute