Shredded ferrous scrap has long been endorsed by steel mill melt shop managers as a feedstock that, provided it has the right chemistry, offers many advantages.
At electric arc furnace (EAF) steel mills, which often rely on ferrous scrap to provide the vast majority of their furnace charge materials, preferences for shredded grades have helped prompt the growth in the world’s auto shredder population.
Convinced that using more shred was likely to produce worthwhile results, Ecuador-based steel company Adelca (Acería del Ecuador) recently installed an auto shredding plant adjacent to its mill and measured the results of shifting to predominantly shredded material to charge its furnace.
In Need of an Upgrade
In a presentation to the Bureau of International Recycling (BIR) Shredder Committee at the organization’s 2013 World Recycling Conference in Shanghai in May, Marion Andres Albuja Rivadeneira of Adelca described the company as “the most important Ecuadorean steelmaker,” having the ability to produce up to 315,000 tonnes per year of rebar and small shapes.
Adelca was founded in 1963 and is situated near Ecuador’s capital city of Quito. While some of its steel products are consumed domestically, it also exports to Chile, Colombia, Perú and Venezuela.
From 2006 to 2008, Italy’s Sider Engineering S.p.A. helped provide and install the technology for what was commissioned originally as a 160,000 tonnes-per-year melt shop.
The EAF technology has allowed Adelca to promote “a virtuous cycle” that entails helping Ecuador to recycle its own scrap and keep its hills and valleys clear of illegally disposed of appliances, vehicles and other items.
Another reason to rely on ferrous scrap has been its effectiveness as a charge material in the melt shop. Although Adelca studied EAF production thoroughly before starting its furnace, after Adelca’s melt shop opened in 2008 Albuja says the company still had plenty to learn by monitoring activities.
“Like most new melters, Adelca began its operation focusing on all the costs related with the process, including energy, labor and additives—but particularly on the scrap, which is really 60% of total cost,” he told BIR delegates.
Adelca’s original mix of scrap included loose, sheared and baled ferrous scrap, including white goods, small shapes, sheet and some auto hulks. The bales proved particularly problematic, said Albuja, as they “had a lot of nonferrous material, such as rocks, nonferrous metals and plastic.”
Because these were the types of scrap most readily available in Ecuador, Adelca’s original scrap mix, as described by Albuja, was:
- 50% pressed and sheared;
- 30% bundled;
- 10% torch cut;
- 5% cast iron; and
- 5% other scrap types.
The overriding characteristics were “low density and low purity,” according to Albuja, which resulted in “long charging and melting times.”
A New Approach
After scrutinizing its procurement and melt shop performance results for more than a year, Adelca devised a capital investment and productivity improvement plan that entailed a major commitment to shredding.
The first step in Adelca’s plan involved buying a new higher voltage furnace transformer from WEG S.A. of Brazil in February 2010. The transformer tied in to Adelca’s next step, the purchase of an auto shredder. “The increased transformer size and power was strategic in that it greatly enhanced the ability to melt a higher percentage of shredded scrap, which must be strategically placed near the furnace walls,” said Albuja.
Despite economies stuck in neutral in many parts of the world, the population of auto shredders seems to be remaining on an upward course. Not surprisingly, China is one of the rapid growth regions.
At the 2013 Middle East Metals Recycling Conference, held in Dubai in March, Scott Newell of The Shredder Co. LLC, Canutillo, Texas, noted that 30 auto shredders now are installed in China and he predicted that it will take only a few years before the shredder population in China reaches 100.
The shredder increase, he said, is indicative of a larger stream of end-of-life cars and appliances that not only will produce ferrous scrap but also additional nonferrous flows. Newell said China also has an expanding network of more than 70 licensed electronic scrap shredding facilities, which likewise will yield more red metal scrap from the postconsumer sector.
In the developed world, auto shredders continue to spread to smaller cities and into regions removed from major metropolitan areas.
In Canada, the Northern Ontario Heritage Fund Corp., Sault Ste. Marie, Ontario, has announced plans to provide $1 million to Brampton, Ontario-based Triple M Metal LP to assist in purchasing an auto shredder for a Triple M Metals facility in Sault Ste. Marie.
“Triple M Metal LP is very excited about the startup of our new, state-of-the-art automobile shredder at our Sault Ste. Marie facility,” says Joe Caruso, president of Triple M. “The new shredder enables Triple M to locally process scrap material originating in [northern Ontario] and provide much needed raw material for the production of new steel.”
The auto shredder is expected to cost $4 million. Triple M operates 16 facilities, including 12 sites in Ontario.
Two months later, Adelca committed to purchasing a 4,000-horsepower shredder from the The Shredder Co., based in Canutillo, Texas, in USA.
“Adelca was convinced that better scrap would greatly improve production,” said Albuja. “We had tested shredded scrap in the blend going into the furnace,” he told BIR delegates, and the company had found it provided better density and cleanliness.
Adelca’s commitment involved using shred at levels not often matched at other mills. “We had reached using up to 40% to 50% shred in the mix charge successfully; we challenged ourselves to learn how to use 80% to 90% of shredded scrap,” he remarked.
By April 2011, both the new furnace transformer and the new shredding plant were installed and operating. “Three months later, Adelca’s objectives were reached,” says Albuja, who says the melt shop’s new mix consisted of 85% shredded scrap, 8% torch-cut, 4% bundles, 2% cast iron and 1% other types of scrap.
In contrast to feedstock that was low in density and purity, the shredded grade was “very high density and very high purity,” Adelca said.
Scott Newell Jr. of The Shredder Co. also has been spreading the word about the results of the Adelca project. At a presentation made in March 2013 at the Middle East Metals Recycling Conference in Dubai, Newell noted that Adelca was able to reduce its “tap-to-tap” steelmaking production time from 67 minutes to 40 minutes.
This gain in production speed has helped convert Adelca’s facility from a 14,000-tons-per-month mill into a 26,000-tons-per-month mill while also decreasing power usage. “The use of shredded scrap has saved $35 to $40 per ton in power, electrodes and [melting] additives,” said Newell.
In his presentation to BIR delegates two months later, Albuja confirmed those results. With its prior scrap mix, Adelca had to make five charging bucket trips to load the 32 tons of scrap it needed for a heat. Now, using 85% shredded scrap, just two charging bucket trips are needed.
Thanks to the greater purity of the material, the company now uses less than half of the lime additive as before. In addition, refractory linings are lasting more than twice as long as previously and electrodes more than 30% longer, thanks to the relative absence of bulky, sharp-cornered bales that can cause damage.
Return on investment also has accrued in the form of energy savings. Even with a higher voltage transformer, Adelca is using 445 kilowatt hours (kWh) to produce one tonne of steel, compared with 580 kWh prior.
And, the mill’s tap-to-tap time is down nearly 41%, which has been a crucial factor toward lifting total hourly productivity from 19.5 tonnes to 36.8 tonnes and total monthly production to 26,500 tonnes.
Adelca’s melting yield has risen from 85% to 92%, creating one more advantage at the very end of the steelmaking process: a decrease in slag production from 20% of output to just 9%.
A benefit at the front end of the process involves the separation of nonferrous metals at a downstream sorting system installed behind Adelca’s shredding plant in October 2012. “Successful recovery was almost immediate,” Albuja commented. “Currently we are selling small quantities of zorba, twitch, zurich and stainless scrap to China and other countries.”
Summing up Adelca’s findings, Albuja stated, “The shredding process has had a strong impact, reducing the overall cost and increasing the melt shop’s productivity. The cost reduction related with shredded scrap use has been approximately $35 to $40 per billet tonne of steel produced.”
Since adding the nonferrous separation downstream equipment, “the value of the nonferrous metal recovered reduces the [net] cost of our scrap between $20 and $25 per tonne,” said Albuja, allowing the company to bid more for auto bodies and white goods.
In Newell’s presentation in Dubai, he commented that while Adelca had to make sizable investments in its shredding plant, the expenditure was nowhere near what it would have been had the company simply added melt shop capacity to expand to 26,000 tons per month without changing its feedstock preparation approach.
Newell predicted that results like these will help convince more steelmakers that the EAF process fed with ferrous shred is a viable way to compete in the future.
The author is editor of Recycling Today Global Edition and can be reached at firstname.lastname@example.org.