SIX YEARS ago, Indian-born Professor Veena Sahajwalla was staring into a steel-making furnace in Indianapolis when suddenly something clicked. What if she tried mixing waste plastic in with the coal at intense temperatures? Could she invent new ‘green steel’?
The science behind the question was elegantly simple. In electric arc furnace steelmaking, coal or coke is needed to trigger carbon reactions at intense temperatures. But carbon reactions, she theorized, could just as easily be generated using plastic that would otherwise be building up in landfills. Steel can’t tell where the carbon comes from so the end product would be identical.
Today, Professor Sahajwalla is the Director of Sustainable Materials Processing at the University of New South Wales (UNSW) in Sydney and her green dream is about to become a commercial reality.
A worldwide license has just been taken out by the Australian steelmaker, Onesteel, in conjunction with UNSW’s commercial arm, NewSouth Innovations (NSi), to turn plastic waste into steel. At Onesteel’s Sydney plant, plastic injected, low emissions steel is already in production.
Her new electric arc furnace process substitutes about 30 per cent of coal and coke with polyethylene plastic waste; reducing pressure on garbage dumps. But, much more significant was the discovery that the plastic mix-in creates a more efficient steel-making process, promising to reduce emissions in one of the world’s dirtiest, but most essential, industrial processes.
After years of laboratory testing, Professor Sahajwalla discovered that her initial hunch during a sabbatical year spent in the United States, ‘up close, hot and dirty’ with the steel-making industry, was correct. Carbon derived from plastic can be used in steel making, thus reducing the amount of coal inside a furnace. But, the realization that the plastic waste ‘mix in’ was actually more efficient than conventional electric arc furnace (EAF) steel making – which runs off large amounts of electricity – was an added bonus. Annually, the world produces about 1.1 billion tonnes of steel, about 40 per cent of that in EAFs. Cutting electricity demand for industrial steel production represents major environmental and cost savings.
Beyond the environmental benefits Professor Sahajwalla is looking forward to a social spin-off close to her heart. Born and raised Bombay, in India; she learnt very early that poor societies cannot afford waste. Everything is re-used and recycled in India’s slums and poor rural communities, she says. The idea that polyethylene plastic – found in everything from shopping bags, to plastic packaging and plastic pipes - will become a valuable raw material for steel-making could lift the economic prospects of the wretchedly poor, who live off picking over the third world’s rubbish dumps.
“The idea I find exciting is the possibility of up-cycling waste, giving it a higher value. In this process we have actually added value to waste. You have rubbish everywhere, this turns it into a whole new business venture.”
From a scientific point of view, the fact that carbon reactions are more efficient when plastic is added to the process is compelling mystery which Professor Sahajwalla’s UNSW teams is still trying to answer definitively in their labs. It seems the plastic aids the “slag foaming” process and may improve furnace efficiency by sitting on top of molten steel like an insulating blanket.
“No one has looked at the uses of plastics at steel-making temperatures of 1600 degrees C, and you can imagine the challenges of working with these temperatures in a lab are enormous. A lot of these reactions are being carried out for the first time,” she says.
Her long-term aim is to develop ‘recycling science’.
“We have never really looked at waste with the respect it deserves. We shouldn’t look at rubbish as waste, but as just another resource and we need to develop the science to match.”
However, she optimistic the momentum for environmental change is now unstoppable. “The environmental tide has turned, she says.
In the meantime, Onesteel has the right to sub-license the technology to more than 300 EAF steel-makers around the world. Onesteel has been testing the commercial viability of the process for two years and found the process reduces energy consumption at a rate of 11.1 kilowatt hours per charge tonne.
“Not only does it cut the industry’s coal use, reducing the amount of coal that needs to be mined, it also used recycled plastic and prevents it from ending up in landfill,” says Adrian Howard, Onesteel’s commercial manager.
Professor Sahajwalla’s own fascination for materials, and the industrial processes which produce them, go back to her childhood in India. She was, she says, an “unusual girl” drawn to big machinery and furnaces. As an undergraduate in India, she was the only girl in her class, and constantly topping exams made is difficult for the boys. As a post-graduate she went to Canada and the United States before being recruited by the CSIRO in Australia, then UNSW.
In between, she married fellow Indian post-graduate, Rama Mahapatra, whom she met in Canada and had twin girls, now 12 years old, Mira and Tara.
“I won’t win the mother of the year award,” she says laughing, about her fondness for steel-making and industrial research.
“But, my daughters are now at an age where they understand that I need to do what I am passionate about. When they get upset with me they just say: ‘You aren’t like other mums’,” she says.
By Louise Williams, Associate Director of UNSW International
Source: http://www.merinews.com/
Forget yourself for others, and others will never forget you.
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