Burning rubber to forge steel

rubber to steel technologyNSW, Australia – “We have started doing all sorts of crazy things,” Veena Sahajwalla told the group of fresh faced scientists and exhausted chemists gathered at the Powerhouse Museum in Sydney, Australia last Friday. A materials scientist at the University of New South Wales in Sydney, Sahajwalla was kicking off the Ultimo Big Night of Science, an event where science geeks had gathered to learn about recycling steel, undiscovered elements and possibly the greatest physicist of our time – Richard Feynman.

Sahajwalla has invented a process dubbed Polymer Injection Technology, which uses rubber from old tires to create steel. It’s no doubt impressive, but as this well spoken woman addressed the crowd, it was hard to imagine her venturing into the crazy.

Then Sahajwalla showed us a picture of people walking amongst giant, ashen mountains. Take a closer look, she said. Those mountains, we soon saw, were in fact huge piles of old tires. Several years ago she saw this pile of waste and recognized it as buried treasure – packed with materials just waiting to be recycled. Now she has found a way to do it.

To conventionally make steel, coke, which is charcoal from coal, and limestone are shoved into a furnace heated to more than 1500º Celsius. The calcium in the limestone scavenges impure elements in the coke, such as silicon and aluminium, creating foamy slag and the product we’re after – liquid iron. Just like cappuccino foam, the slag sits atop the liquid iron and insulates it, speeding up the processes of converting coke to iron.

Sahajwalla found that replacing some of the coke with recycled rubber created a more effective slag blanket. The extra heat produced from it reduced energy consumption, and produced more steel. It was the ultimate win-win. Following successful commercial trials in 2007, the technology is now being used in steel mills across Australia and has diverted well over 70,000 tyres from landfill. “It’s so satisfying and so exciting,” she said. Her excitement was infectious.

But then, the three-man science/rock/cabaret act known as the Great Big Science Gig appeared with rhymes that would make Dr. Seuss cringe. In a ditty about the Square Kilometre Array, one notable couplet was “it will look past the sky/ as we dare to ask why”. Youch.

Their hit of the night though was an ode to the unnatural elements of the periodic table, which admittedly made me giggle. “My brothers and sisters don’t have names/ but they made it to the table because of 15 milliseconds of fame”. By the interval, I was ready for a glass of wine.

Wine in hand, I made my way over to a packed table of people. “Where is my sugar molecule?” asked a very stressed Edwina Hine from the Royal Australian Chemical Institute. Turns out she was making sherbet powder. I quickly joined in, combining half a cup of icing sugar with a teaspoon of jelly crystals, bicarbonate soda, and citric acid into a plastic bag. Without a thought for etiquette, I licked my finger and shoved it into the mixture. Now, this was fun science. The citric and bicarbonate soda mixed with the saliva in my mouth to form carbon dioxide gas, giving the sherbet its fizz. Before I knew it, the interval was over.

A lone man entered the stage. It was a Lawrence Krauss, author and theoretical physicist at Arizona State University who had come to discuss Quantum Man, his new book about the Nobel prizing-winning physicist Richard Feynman. “But as my soon-to-be ex-wife says, it’s all about me,” Krauss wryly told the crowd. Forget the rock band, this was shaping up to be the best gig of the night.

For the next 40 minutes Krauss held us captive, revealing how Feynman, a normal Jewish boy from Long Island, helped develop the atomic bomb and uncovered the secret interaction between radiation and charged particles. Turns out, he even taught Krauss how to dance.

Towards the end of a talk peppered with fascinating anecdotes, Krauss offered some advice to budding scientists in the audience. “You have to do the experiments to see if an idea is crazy,” he said. “The world is the way it is, whether you like it or not.”

Sahajwalla knows this all too well. She shoved rubber into a furnace at 1500º Celsius to see what would happen. Not so crazy after all.

Source: New Scientist