tyre stewardship

UNSW centre uncovers green steelmaking

A University of New South Wales project has developed a world-first environmentally friendly process to recycle end-of-life plastics and rubber tires for steelmaking.

Writing in devex, Veena Sahajwalla, founding director of the Center for Sustainable Materials Research and Technology, argued steelmaking was one of the most carbon intensive industries, with many steelmakers conscious of reducing the carbon footprint.

“There are many other good sources of carbon, and many very problematic waste streams are carbon rich. These include waste tires, waste plastics and high volume agricultural wastes,” she wrote.

Ms Sahajwalla wrote that in Australia, some 20 million passenger tires require disposal annually, of which only 23 percent are recycled, 64 percent go to landfills and the remainder are dumped illegally, despite bans on disposal in landfills in some Australian states.

She argued green steelmaking was an economically attractive way of re-using waste tires, which substituted coke with an alternative source of carbon, using it as a carbon injectant.

“The result is a novel recycling solution that requires only minimal modifications to the manufacturing process and retains the quality and performance of the end product,” she wrote.

“PIT introduces a precisely calibrated mix of crumbed waste into the furnace to optimize outcomes. We spent a number of years researching and understanding the high temperature reactions that take place when waste tires partially replace coke, enabling us to optimise the operating parameters of the furnaces.

“As the new polymer-coke mix improves the foaminess of the slag, it improves furnace efficiency, while absorbing an otherwise problematic waste streams destined for landfill. Worldwide we have absorbed millions of waste tires, reduced coke usage significantly, achieved savings in electricity and reduced toxic gases, as the polymers are completely consumed at the high temperatures used.”

She says the organisation’s patented PIT ‘green steelmaking’ technology has been already integrated into commercial steelmaking operations in Australia, including Thailand, South Korea and the United Kingdom with discussions underway for other locations.