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Cooler times on the hot end

May 31, 2017 | 08:00 PM | Myra Pinkham

Incremental advances keyed to cut costs are the order of the day with the linkage of meltshop operations through automation setting the stage for ‘intelligent’ steelmaking.

While there’s no questioning the impact of innovation on steelmakers’ bottom line, recent technological advances along the steel production flow line—particularly the hot end—have been essentially incremental in nature. Breakthrough or “leapfrog” technologies the dimension of thin slab casting and the subsequent debut of the flat-rolled mini-mill have been followed by decades of more modest technological tweaks and advances, a pattern industry insiders expect to hold over the short- to medium-term future.

Reasons behind what could be considered a holding-plus pattern vary with weak financials—except in a very few select cases—topping the list. Given the difficult times the steel industry has faced in recent years, investment dollars have been hard to come by, Alexander Fleischanderl, vice president and technology officer – upstream, for Primetals Technologies observes.

This and the lack of any true “leapfrog” advances in either electric arc furnace (EAF) or basic oxygen furnace (BOF)-based steelmaking has steered the lion’s share of recent melting and casting research and development efforts in the direction of incremental advances focused on cutting costs, Fleischanderl said.

Tough financial tides and sentiment underpinning them may be turning, however. William H. Emling, vice president of the steelmaking and casting division of Pittsburgh-based SMS USA LLC, noted that there was a lot of optimism at the recent AISTech conference in Nashville, Tenn., with equipment suppliers fielding inquiries not only for auxiliary lines but also for large, capital equipment. “But the jury is still out on whether that interest will translate into actual orders,” he cautioned.

Johann (Hans) Penn, Primetals Technologies’ vice president of continuous casting, observed that although a number of plants are approaching the end of their effective life, steelmakers seldom invest in new capacity. “Although there are some big projects, the ratio of new investment vs. modernization business is about 25 to 75 percent,” he said. Penn noted that most of those expenditures are keyed to optimize the production process and secure higher prices and healthier margins.

Alberto Voltolina, vice president of sales at Danieli Corp. North America, Cranberry Township, Pa., expects the majority of forthcoming technological advances to continue to be incremental in nature.                                      

“Steelmakers aren’t making purchases just to buy new equipment,” he commented. “They want to see that investment add value.

“To do that, you can’t just turn the whole process upside down,” Voltolina emphasized. “You need to approach it step by step.”

Emling agreed, stating that SMS, like many other equipment suppliers, has been focusing its steel-related development efforts on addressing the steep challenges that have confronted steelmakers in recent years.

Counted among those challenges are a pressing need to:

• Successfully compete against alternate materials for market share
• Secure a competitive position through lean processes and cost structures while using resources carefully
• Continuously enhance product quality while operating at high productivity levels
• Control operating costs, maintenance expenditures and energy costs
• Be flexible regarding raw materials, production planning and order book changes.

To that end, Emling, pointed to the beginning of a push to develop what has been referred to as a “smart steel plant,” which could enable “intelligent steelmaking” and, eventually, even autonomous steel production by networking and collaborating humans and machines to optimize and make the steelmaking process more dynamic.

“We have already developed a lot of automation and controls, using tools such as artificial intelligence and virtual reality to digitize and optimize the process in real time within the value chain,” Emling pointed out.

“Eventually, we could see completely unmanned operations,” Fleischanderl predicted. This could start with fully automatic scrap yards where not only scrap quality but also inventory levels could be identified by sensors and, if more stocks are needed, relevant information could be sent directly to the purchasing department, he said.

While steelmakers have upped their automation game, adopting tools to perform remote temperature measuring, hot metal sampling and scrap charging, the industry has yet to achieve fully automatic steelmaking operations. “The industry isn’t ready for that,” Fleischanderl said, noting that even if steel mills eventually become more autonomous, there will always be a need for people. “While the automated system will give the best proposals of what to do, there will continue to be a need for personnel in the control room to interferact as needed,” he noted.

In the past several years, the use of robotics in melting and casting operations as well as downstream of the melt shop has been increasing, particularly in challenging and potentially unsafe operations such as sampling temperatures and dispensing casting powder in the tundish, Fleischanderl said. Robotics bring with them several advantages. Not only does their implementation result in the generation and delivery of reliable, reproducible information to a mill’s automation system and provide for greater digitalization of plant operations, he noted, but the use of robotics keeps workers out of challenging environments, which translates into safety benefits.

Many of the steelmaking challenges cited by Emling apply not only to hot end operations but throughout the entire steelmaking process. Indeed, the different phases of steel production—melting, casting, rolling and finishing—are more closely linked today than ever before.

The link between the liquid phase and the production of finished steel products, casting has always been what Penn describes as “the bottleneck in the production process.”

To address that “bottleneck,” equipment makers have linked the processes together through technological advances. Approaches recently debuted by Primetals Technologies, for instance, include its’ Arvedi ESP (Endless Strip Production) and WinLink, which combine casting and rolling processes for flat and long products respectively.

Primetals Technologies has also linked secondary metallurgy and casting through its DynaPhase process model, which enables both online and offline chemical analysis of the melt in the ladle furnace and potential impacts downstream during the casting process, Penn noted. The model also aids in the development of new steel grades, he added.

In an effort to speed production, steelmakers have been turning their attention increasingly to the latest casting technologies Voltolina observed. Mills are looking for features such as soft reduction and electromagnetic steering, which allow for the molten steel to be cast more uniformly on it way from the tundish to the rolling mill.

One example is the Danieli Universal Endless (DUE) vertical continuous strip caster, which can accommodate a single slab thickness measuring up to 110-millimeters after dynamic soft reduction and has a casting speed of up to seven-meters per minute. Voltolina describes the DUE as very flexible and capable of casting such high value-added steels as HSLA, electrical steels, advanced high-strength steels (AHSS) and silicon pipeline API grades.

SMS has developed a number of continuous casting technologies that allow customers to enter new areas of business, Emling noted. In the long products arena, the company has commissioned a bloom caster capable of casting world-record sized blooms—measuring one-meter in diameter—at Taewong Co. Ltd. in South Korea.

In flat products, SMS has commissioned a slab caster at Germany’s Dillinger that is capable of casting slabs measuring up to 600-mm thick by using a purely vertical casting approach. Working with Salzgitter AG, it has also developed a belt-casting technology that allows for the production of ultra-thin—17-mm thick—slabs on a moving belt.
“Steelmakers are looking to produce thinner and stronger steels and to do so faster,” Voltolina said. “And it is difficult for them to do that if they don’t have the right technologies.”
Whether serving the automotive, discreet manufacturing or other demanding markets, mills are being driven by their customers to deliver not only clean but ultra-clean steels. 

“The global push for energy efficiency and stricter carbon dioxide emission regulations has significantly increased the importance of clean steels in the automotive industry,” Jay Murthy, director of product development and technical services for Jackson, Mich.-based Gerdau Special Steel North America, observes. Gerdau’s research and development, process and product metallurgists have made significant strides in this arena through enhanced melt practices and strict process controls to produce bearing-quality steels processed through its continuous caster.

“These improvements have been validated using the latest automated scanning electron microscope, extreme value analysis and ultrasonic immersion testing equipment,” Murthy said.

Similarly, TimkenSteel Corp., commercialized its Ultrapremium™ steel product last year, a family of steels which the Canton, Ohio-based steelmaker believes to be the cleanest and most consistent quality, air-melt product available.

Ray Fryan, TimkenSteel’s vice president of technology and quality, describes the product as a potential substitute for much costlier, vacuum-melted steels in gear systems applications. The ultra-clean steel went into production at one gear maker last year and is in active trials at about a dozen other companies.

“We have two potential groupings of customers for this product,” Fryan said. One is those who are experiencing a problem with an existing design that Ultrapremium could possibly solve.  The other is a customer who, thanks to Ultrapremium’s performance properties, could possibly redesign, downsize and reduce the weight of a part while maximizing its’ power density.

Overall process quality control for new steel grades is a major focus of technology development efforts and one that Fleischanderl said involves a number of challenges, not the least of which is to find a niche at an acceptable price level for these new-breed, high-quality steels. That requires using new recipes, new features and new quality management through rules-based automation to insure that steelmakers achieve the quality and the properties they want and can make rapid, correct decisions, he said.

With customer demand for product quality growing increasingly stringent, companies have developed new tools to answer the call. Primetals Technologies, for example, has developed a high-temperature casting system, dubbed DynaTac, to help steelmakers control the strength and temperature of the melt during casting as well as a new cooling system, called DynaJet Flex, which with its wide operating range offers steelmakers more flexibility, Penn said.
Fleischanderl noted that while ample scrap availability worldwide tends to promote the growth of electric arc furnace (EAF) steelmaking, it has also spurred integrated producers to seek ways to use more scrap in their hot metal charges—up to 50 percent vs. 15 to 20 percent currently.

Primetals Technologies’ Jet Process technology, which features a combined converter that allows 1,200 deg. C. hot, oxygen-enriched air to be blown through the bottom as well as the top of the basic oxygen furnace (BOF), and exploits chemical energy, could help them achieve this goal, Fleischanderl noted.

With the Jet Process technology, post combustion occurs inside the vessel, allowing for the combustion of carbon and carbon monoxide, making it more energy- and cost-efficient. The first industrial installation of the Jet Process technology is scheduled for commissioning in China late this year.

Another major recent EAF-related innovation involves direct heating of scrap in the furnace shaft, Fleischanderl noted. Primetal Technologies’ EAF Quantum, which uses this technology, was first installed a year and a half ago at Talleres y Aceros SA de CV (Tyasa) in Mexico, and has delivered significant energy savings there.

Tyasa’s energy consumption is currently pegged at 280 kilowatt hours (kWh) per ton of steel produced, he said, pointing out that EAF-based operations that don’t preheat their scrap tend to consume 350 to 380 kWh of electrical energy per ton of steel.

While innovation in the near term is likely to materialize in the form of measured, incremental advances, equipment makers predict more substantial technology shifts could emerge going forward. On the specialty steel front, Penn said he expects to see some movement from ingot casting to semi-continuous casting in an effort to optimize both yield and product quality and to allow better control of the cooling process.

Looking further out, prognosticators see the possible use of hydrogen as a substitute for carbon in steelmaking. This is being considered not only by steelmakers but also for the production of direct reduced iron, John Kopfle, director of corporate development at Midrex Technologies Inc., Charlotte, N.C., noted.

Such a switch would bring with it a significant environmental benefit, especially if the electrical power consumed in the production process comes from alternative sources such as wind or the sun. While Fleischanderl said he doesn’t see any major technological issues doing this, hydrogen must first become available on a commercial basis at an acceptable price, which he suggested is likely still at least a decade or two away.


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