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Exploit and Explore

Nov 29, 2017 | 06:00 AM | Myra Pinkham


Steel mill equipment suppliers are keenly aware of the challenges their customers face and the critical importance of providing mills with innovative solutions to hone their competitive edge.

Although there is no single path to achieving that objective, there are a handful of shared goals orchestrated around helping steelmakers increase their cost and energy efficiency to competitively produce the high-quality steel their customers need and demand. The issue is whether to pursue such goals by further refining existing technologies or investing to invent, test and introduce a totally new technology.

In either case and as part of their efforts, mill equipment suppliers are pushing for the implementation of advanced automation, digitalization, and even artificial intelligence, the hand tools of what is known as Industry 4.0 or the Internet of Things (IoT). To date, however, a majority of suppliers see the digitalization of the steel industry as in its’ early stage and lagging the progress charted by some other industrial sectors.

As a whole and based on interviews with top steel equipment suppliers – most of them international companies headquartered offshore – mills are steering their investment outlays into upstream operations with U.S. mills seen as somewhat slower than their counterparts in Asia and Europe to pull the trigger on such investments.

Francesco Memoli, executive vice president of American operations for Italy’s Tenova SpA. is quick to point out that the emphasis today among mill customers is on adding value vs. increasing capacity. Many steelmakers are turning to what Memoli terms as “technological exploitation” – investments in technologies that deliver immediate returns on the safety, environmental and cost fronts at existing facilities. For the supplier, this translates into helping steelmakers operate the facilities they already have more efficiently and exploiting those facilities to their maximum capabilities.

The “exploitation” phase can be followed by implementing certain “exploration” technologies, many of which can only be cost-justified in the context of a greenfield plant, Memoli acknowledges.

In recent years, of course, the U.S. has hosted the addition of only two new from-the-ground-up steel mills. Big River Steel LLC, based in Osceola, Ark., began ramp-up at the end of 2016 while Commercial Metals’ Durant, Okla., reinforcing bar micro-mill, is expected to come online by the end of this year.

To help mills further exploit the capabilities of existing operations, equipment suppliers are drawing a bead on the quality of the raw materials charged into their furnaces. Electric arc furnace (EAF) operators looking for greater raw material flexibility and to produce new, higher grades of steel are fueling the demand for alternative iron units, including both direct reduced iron (DRI) and hot briquetted iron (HBI). Alexander Fleischanderl, vice president and upstream technology officer for Primetals Technologies, expects global DRI and HBI production to increase some 40 percent to about 105-million tonnes by 2022.

Tenova’s Memoli points out that the stepped-up drive for alternate irons – in conjunction with affordable prices for iron ore fines and pellets – gives EAF steelmakers in countries with access to low-cost natural gas a significant environmental advantage. Opting to use a DRI plant vs. a blast furnace to produce alternative iron could enable a steelmaker to trim carbon dioxide emissions by more than 50 percent, he notes.

Tenova has been working to develop technologies that would further slice emissions with the aim of achieving a true zero-carbon footprint for iron and DRI production through the sequestration of the carbon dioxide created during the DRI production process.

Ternium, one of Tenova’s sister companies, captures about 30 percent of the carbon dioxide generated during the reduction process at the DRI plant serving its’ steel mill in Monterrey, Mexico according to Memoli. Ternium sells that carbon dioxide to an industrial gas supplier, which, in turn, sells the gas to the food and beverage industry, he says.

Various equipment suppliers have also been focusing on developing technologies that enable the better utilization of off-gases generated during EAF steelmaking. One of these is Germany’s SMS Group, which installed its first SHARC shaft EAF furnace at Greece’s Hellenic Halyvourgia SA (HLV)several years ago, but recently outfitted the mill with more advanced oxygen-burner technology. The SHARC technology uses hot off-gases to efficiently preheat scrap.

“While SHARC is a relatively simple operation, the energy savings are tremendous,” Bill Emling, vice president of SMS USA LLC’s steelmaking and casting division, claims. He credits the technology with allowing the production of steel at less than 280-kilowatt hours per ton at a capital cost that isn’t much greater than that for a conventional EAF.

Unlike many other off-gas recovery processes, SHARC is a vertical technology, which involves the rise of off-gases through two crescent-shaped shafts that surround the DC electrode, Emling explains. “Preheating the scrap vertically above the furnace is more efficient and less intrusive to the operation than a horizontal, scrap-feeding system, he maintains.

Tenova has also introduced a technology engineered to insure steelmakers capture and conserve the energy contained in furnace off-gases. Called iRecovery, the technology consists of a waste-heat boiler (WHB) outfitted with a radiant and convective section that can completely process waste gas at temperatures of about 1,700 down to 200 degrees Celsius. Pressurized water at the boiling point feeds the WHB, where it is converted into steam through the heat exchanger with the waste gas.

Primetals Technologies is pursuing several goals communicated by its customer base – energy and cost savings and the consolidation of production processes – by developing technologies aimed at both flat and long product steel producers Fleischanderl says.

In the flat-rolled arena, Primetals debuted its endless strip production (ESP) process several years ago. ESP produces hot strip in a continuous, non-stop casting and rolling process. A total of four ESP lines are currently in operation worldwide with two more slated to begin production in 2018.

“With this technology, you are able to produce a final, directly cast and rolled product within 10 minutes, as opposed to doing so in several days with a conventional process, which involves making thick slabs that are then cooled down, reheated and rolled down,” Thomas Pfatschbacher, Primetals Technologies’ head of casting, rolling and ESP, points out.

Because ESP allows steelmakers produce high-quality hot-rolled coils as thin as 0.8-millimeter – a thickness normally only achieved with cold rolling – the output could be sold as a substitute for cold-rolled steels in certain applications, Pfatschbacher notes. This results in significant energy savings as well as manufacturing cost savings of up to $15 to $20 per ton of hot strip produced compared with conventional casting and hot rolling.

Primetals has developed a similar technology for the long products market. Called WinLink, it involves the endless casting and rolling of steel billets without requiring cool-down or reheat. Primetals Technologies is currently installing its first WinLink plant at GPH Ispat Ltd. in Bangladesh, where it is being combined with Primetals’ EAF Quantum scrap melting and steelmaking process. Quantum uses hot off-gases from the EAF to preheat scrap.

The energy savings achieved by the WinLink technology alone is expected to amount to about 33 percent vs. other long product, steelmaking processes, Fleischanderl calculates.

Primetals Technologies is also partnering with LanzaTech, a U.S. biotechnology company, to convert carbon-rich off gases into chemicals such as ethanol, Fleischanderl notes. The equipment supplier sees these technologies as an intermediate step to reduce the steel industry’s carbon footprint. Within two decades, Fleischanderl expects green hydrogen will widely replace carbon as a reductant.

While RH degassing is not a new technology per se, SMS USA’s Emling points out that the installation of the degasser at Big River Steel marks the first time such a unit has been installed by a U.S. EAF producer. The RH degasser will enable BRS to reduce the carbon and nitrogen in their steels to lower levels on a more reliable basis than is possible using a vacuum tank degasser, a technology certain other domestic EAF producers have installed.

Big River opted to go the RH degassing route based on its’ intention to eventually produce a large volume of grain-oriented and non-grain oriented electric steels.

While it might be easier to implement RH degassing at a greenfield facility, Emling stops short of ruling out the possibility of other EAF steelmakers upgrading to RH degassing, providing they have an adequate footprint to do so.

Casting technologies have also been the target of ongoing developments. One of these is the belt casting technology (BCT) developed by SMS in combination with the German government, Clausthal Technical University and Salzgitter Flachstahl GmbH to cast 15-mm thick steel slabs.

By pouring the molten metal onto a belt and forming the steel horizontally, BCT eliminates bending and unbending during the cast, Emling explains. This allows the casting of extremely difficult grades of steel – including advanced high strength-steels with very high levels (17- to 20-percent) of manganese   – that have never been cast before, he says. In addition, BCT can be installed in a relatively small existing facility and doesn’t require adding a new water treatment facility.

On the thick end of the steel casting spectrum, SMS recently commissioned what Emling terms as the world’s thickest slab caster – capable of producing 600-mm slabs – at Germany’s Dillinger Group. The unit produces the slabs vertically without requiring any bending. Slabs are cut while they are still in a vertical mode and are then raised to the surface on an elevator.

Further downstream of the hot end, more mature rolling and finishing technologies are stirring renewed interest along with a push to customize equipment to fit specific steelmakers’ needs.

Tad Sendzimir, president of Waterbury, Conn.-based T. Sendzimir Inc., reports a rekindling of interest in the planetary rolling mills used to reduce relatively thick incoming slabs by as much as 96- to 98 percent in a single pass. Prevalent in the 1960s and early 1970s, the planetary mills fell out of favor due to their relatively modest output.

“But we are now seeing some renewed interest in relatively small plants – about 500 tons per year or less – for pipe skelps and certain other relatively narrow width, high-carbon and medium-carbon steel applications,” Sendzimir says. This is not dissimilar to recent interest in rebar micro-mills, he notes.

Elsewhere on the steel rolling front, Primetals Technologies’ Power Cooling high-pressure, cooling technology is said to enable steelmakers achieve much higher cooling rates, and, in some cases, produce new, high-quality steel grades with lower percentages of certain expensive alloying ingredients, such as niobium.

The approach is an alternative to “micro-alloying” such steel grades to bring the material up the strength curve, Keith Watson, vice president of SMS USA’s flat rolling division points out. “It is cheaper to do this with water than with alloys,” he adds.

Most upgrades to downstream equipment are custom-tailored, however, and can vary significantly from one mill to another. “The best way to determine what is needed is by conducting engineering studies,” Watson says. “(This involves) taking a look at a steelmaker’s existing equipment and product mix, determining what changes they would like to make and whether (the desired results) are best achieved by upgrading some equipment or if entire new equipment is required.

“Sometimes, a heavier piece of equipment, such as a larger mill stand or coiler, is needed” Watson adds. “Or it could be that they need to make adjustments to their galvanizing furnace. It depends on what equipment they have installed, their immediate goals and what they want to achieve in the future.”

One major advance afoot throughout the steelmaking continuum is the implementation of increased automation. “We are entering the age of Big Data and greater digitalization,” Primetals Technologies’ Fleischanderl says. By evaluating mounds of data collected by sensors, companies can analyze the cause of failures and make decisions that enable them to optimize productivity, reduce production costs and increase the reliability of their plants, he points out.

“Adaptive learning, artificial intelligence and predictive capabilities for both production planning and maintenance give mills the ability to do things they weren’t able to do in the past,” SMS USA’s Emling adds.

Such digitalization and optimization allows steelmakers to operate their processes in a much narrower range of deviation, Pfatschbacher observes. This leads to higher process stability and process efficiency, as well as better product quality, he adds. And Big Data analysis can also be used to help develop higher-end steel grades.

Looking ahead, Tenova’s Memoli predicts new steel plants will host more “real robots, not just robotic arms.” A number of robots are currently in operation at Tenaris’ Bay City, Texas, pipe mill, he notes. Implementation there has lifted the pipe maker’s productivity, helped cut costs, and most importantly, perhaps, provided greater worker safety.

The Tenova executive also expects to see the increased adoption of additive manufacturing – not just using stainless, tool and other specialty steels but carbon steels as well.

“Additive manufacturing is an industry that is growing by 35 percent per year,” Memoli observes.

While globally only 300,000 to 400,000 tons of steel powder is consumed at this time, given this rate of growth it could become a significant market in the next 10 to 15 years, he says.



 

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