SIEMENS

Giovanni Arvedi is a true cavaliere, a gentleman of the old school, but he’s also — in another translation from Italian — a Cavaliere del Lavoro, a knight of work. That’s the name of the order of merit awarded to him by the Republic of Italy in 1984 in recognition of his service in the fields of industry and commerce. In 2009 he received the prestigious Bessemer Gold Medal from the International Institute of Materials, Minerals and Mining in recognition of "his audacious approach to hot strip manufacture."
Arvedi’s success story actually began in 1973, when he founded the Acciaieria Tubificio Arvedi plant in Cremona, which was equipped with what were then the most advanced technologies available for manufacturing steel and producing hot-rolled tubes. In the early 1980s Arvedi acquired a significant share of the Falck Group and with the purchase of Falck’s Celestri subsidiary acquired one of the largest sales and service companies in Italy’s steel processing industry. Today the Arvedi Group has over 2,000 employees and annual sales of more than €1.3 billion.
However, it was only recently, following a series of impressive technological innovations, that this industrialist from northern Italy realized his greatest accomplishment: completely endless strip production (Arvedi ESP) — a new and highly efficient steel production process.
The idea behind Arvedi ESP is simple in principle. In conventional plants, steel cools to the ambient temperature during a number of production steps and is then reheated (at considerable cost) before being turned into the end product — sheet steel — in a rolling mill. In the Arvedi ESP production process, instead, steel is rolled while it is still hot, thus saving energy, and is processed into sheet steel in a single, seamlessly-linked process.
In Cremona this process begins as it does in every conventional steel mill. After tapping, the molten steel is cast into a strand. Like a very long carpet, the glowing-hot band flows along the production line. In conventional continuous casting steel production, the molten steel is cast into slabs that are typically 23 cm thick, which are then allowed to cool and harden. The slabs are stored until they are subsequently heated again just prior to being rolled to a customer-specified thickness.
"Thanks to Arvedi ESP’s innovative process technology, remarkable savings in terms of energy use and costs are achieved in the new Cremona mill," explains Andreas Jungbauer, sales manager at Siemens VAI, the company that built the facility for Arvedi in late 2007. "Instead of cutting the steel strand and storing it for a period, in Cremona it’s left in one piece and moves along the line in a single process from casting to rolling to coiling the finished sheet steel on a coiler. Because the process doesn’t require subsequent reheating of the steel, up to 45 % of the energy that would be needed in a conventional mill can be saved. In Cremona, only 135 kWh per ton of steel are needed, an unprecedented figure in the industry," says Jungbauer. Naturally, the process also reduces associated CO₂ emissions generated by the plant to a similarly dramatic extent. It also lowers process costs by as much as 50 %.

Less Energy, Higher Quality. All of this may sound simple, but in terms of process technology it’s a very formidable challenge. Jungbauer explains: "In contrast to conventional mills, the temperature of the steel strand in the Arvedi ESP process falls only slightly after casting. Then, as soon as it has attained the solid phase in a temperature range from 1,100 to 1,200 °C, it goes through the first roll set in the high reduction mill, reducing the thickness of the strand to between 1 and 2 cm."
After initial rolling, the strand must be reheated only slightly in a ten-meter-long induction furnace. This electric furnace, with an installed power of 30 MW, is more precise and therefore more efficient than the furnaces normally used in the more than 200-m-long gas-fired conventional steel mills that have to heat steel from ambient temperature to more than 1,000 °C. In terms of heating demand, this means a saving on the order of one magnitude (in other words, 10 times).
After heating, the second rolling process begins in the finishing mill, in which the thickness of the hot strip is reduced down to as little as 0.8 mm, depending on customer requirements.
"The rolling process in the finishing mill demonstrates another advantage specific to Arvedi ESP technology — endless rolling," says Jungbauer. "Previously, semi-processed hot strips had to be re-fed individually into the rolling mill. That’s a high-risk process that tends to result in numerous imperfections on every sheet, even when everything goes well. Endless rolling in the Arvedi ESP process avoids threading problems typical of conventional batch production."

Sophisticated Process Control Technology. After leaving the finishing mill, the strip passes over long roller tables and is cooled with water before coiling. "Conventional processes are inferior to this step," says Jungbauer. "because it is not possible to produce ultra thin gauges without encountering production problems or lowering productivity. But with Arvedi ESP technology the steel band is always pulled tightly. As a result, it is possible to avoid a wide range of threading-related problems."
The entire process for the production of a hot rolled coil is carried out in only 3.5 minutes on a line that is 190 m long from the point of solidification to the final hot rolled coil — a world record.
But the uninterrupted process demands a lot from its associated control technology, which must precisely synchronize the individual production steps with a margin of error of only fractions of a second.
In developing a customized control system, Siemens applied its expertise gained through many years of experience in other caster and rolling mill projects. Pyrometers at various control stations, for example, continuously monitor the temperature of the steel, which moves through the plant at caster speeds of up to 7 m/min. In its role as an industrial partner at the Arvedi mill in Cremona, Siemens is the first company worldwide to have implemented this process on the basis of Giovanni Arvedi’s patents.
Initially, annual production will be in the range of 2 mill. t of steel, with an option for expansion to over 3 mill. t. Industrial production got under way in June 2009 following a successful test phase.
Next to the steel plant is a field of sunflowers, a fitting symbol of climate-friendly technology based on energy conservation. Here, in one of the world’s most energy-intensive industries, steelmaking has succeeded in a highly environmentally-friendly manner.
What’s more, the end product, thin steel sheet in coils weighing up to 32 t for delivery to customers, is of superior quality to conventional steel products. Indeed, what sets steel produced using Arvedi ESP technology apart is its excellent dimensional precision, surface quality, and homogeneous internal structure.
In addition, the Arvedi process eliminates the need for the otherwise commonly used cold-rolling process, which entails subsequently rolling the steel, for instance for automotive production. With its extensive experience in industrial automation and sensor technology, Siemens was deemed the right partner for industrial implementation of Giovanni Arvedi’s vision. As licensee, Siemens now markets the innovative technological solution worldwide.
The cavaliere is proud of his pioneer steel mill. But Arvedi is nothing at all like the classic image of the knights of old. Those knights disappeared from the scene, after all, when unexpected innovations such as well-organized infantry and the introduction of firearms made their steel armor essentially useless.
The modern knight, Giovanni Arvedi, on the other hand, is open to technological innovations because they give him a decisive advantage over competitors.