One Simple New Technique Promises to Transform the Steel Making Process
October 15, 2012 -
Some promising recent news from Australia indicates that the steel industry could be on the cusp of another major innovation that could transform the manufacture of lightweight AISI 4130 and 4340 grade steels. It soon may become even less expensive and more energy-efficient to outfit airplane bodies and vehicle suspensions with these aircraft quality steel alloys.
This new development involves a key part of the steel making process. Normally, steel is produced by combining coal, coke and iron slag at extremely high temperatures. The coal and coke cause "slag foaming," an important reaction that releases gases from the slag. This helps to purify the slag and render it suitable for further processing. Although the process is straightforward, it is energy-intensive and can give off some toxic byproducts.
It appears that replacing some coke with natural polymers like those found in rubber can increase the efficiency of the electric arc furnaces that produce 4130 and 4340 grade steels. The switch may also decrease emissions of carbon and other toxic byproducts. Even better, it appears to enhance slag foaming to create purer batches of steel.
What's so revolutionary about this development is its simplicity. No special blend of rubber polymers is necessary to increase the efficiency of the steel making process. In fact, the Australian researchers who uncovered rubber's steel making potential found that old tires worked perfectly well in blast furnaces.
In trials, a blend of 70 percent coke and 30 percent rubber reduced energy consumption by 3 percent while increasing steel output by up to 4 percent. Meanwhile, the amount of carbon necessary to maintain the furnace's internal temperature decreased by 12 percent. Total emissions of toxic gases like carbon monoxide and sulfur dioxide decreased significantly as well. Over time, the cleaner-burning fuel has significantly extended the working lives of the electrodes that power the trial mills' furnaces.
During these trials, two Australian mills recycled about 75,000 tires that would otherwise have sat in landfills and served as breeding grounds for malaria-carrying mosquitoes. After standardizing this method of production, the Australian steel industry has recycled over one million tires to date. Were the global steel industry to adopt the new method completely, countless millions of old tires could be recycled each year.
Thanks to the hard work of some clever scientists, the manufacture of America's aircraft quality 4130 and 4340 grade steels may soon become significantly more efficient and easier on the environment.