Used car tyres can be turned into steel

Professor Veena Sahajwalla
Wednesday, 4 March, 2009
Bob Beale

Hundreds of thousands of Australia's used car tyres could be recycled every year and turned into steel, thanks to a discovery that rubber can be partially substituted for coke in electric arc furnaces.

Invented by UNSW materials scientist Professor Veena Sahajwalla, the new technology not only removes used tyres from the waste stream but also cuts the energy demands, costs and gas emissions associated with steelmaking.

The research was featured at the official launch on 4 March of the new UNSW Centre for Sustainable Materials Research and Technology (SMaRT), by the Minister for Innovation, Industry, Science and Research, Senator Kim Carr.

Known as polymer injection technology, the process substitutes some of the coke used in steelmaking with other carbon-rich materials. Professor Sahajwalla earlier showed that waste plastics could be diverted from landfill dumps and used in this way as well.

OneSteel, which has licensed the patented technology and has developed it in partnership with Professor Sahajwalla, has now successfully trialled the new process at both its Sydney and Melbourne-based electric arc furnace facilities.

At OneSteel's Sydney Steel Mill, which produces steel billets using mainly scrap steel, the trials showed the mill has potential to recycle more than 100,000 passenger car tyres a year. At its Laverton facility, near Melbourne, the mill has already been converted to the polymer injection process and has the potential to recycle more than 200,000 tyres a year.

At both mills, trials demonstrated that the process makes steelmaking cheaper, uses fewer natural resources and less electrical energy, and reduces emissions of nitrogen oxide, carbon monoxide and sulphur dioxide.

"We have seen an improvement in our cost efficiency while making a positive impact on the environment," says Mr David Knights, OneSteel's General Manager, EAF and Casting.  "This technology is a win for steelmakers and a win for the environment."

The SMaRT Centre, directed by Scientia Professor Sahajwalla, was established to work with industry to develop innovative materials and processes to help achieve sustainability targets. Benefits include increased recycling of process and product waste, significant reductions of energy intensity and greenhouse gas emissions as well as development of materials with longer service lives.

It is supported by the UNSW Faculties of Science, Engineering, Built Environment and ADFA,

and brings together internationally recognised researchers in the fundamental sciences of materials, process engineering and technology transfer. It includes about 20 researchers, 40 postgraduate students and corporate industry partners.

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UNSW media liaison: Bob Beale 0411 705 435