Green Steel : A UNSW/OneSteel collaboration
UNSW’s world-first patented “green steel” making process, Polymer Injection Technology (PIT), is optomising electric arc furnace steelmaking in Australia and overseas with significant environmental benefits and cost savings.
A productive partnership with the Australian steel manufacturer, OneSteel, enabled UNSW to take PIT through pilot trials and industrial testing to commericalisation and licensing, in Australia and overseas.
Green steel was named in the 2012 List of Innovations that Could Change the Way we Manufacture by the Society for Manufacturing Engineers.
The process, invented by Professor Veena Sahajwalla, emerged from the novel proposition that waste plastics, or polymers, and used tyres -- significant global waste burdens -- could be absorbed in EAF steel making; an industry which has remained largely unchanged for decades in its reliance on coke and coal.
She discovered that by introducing a granulated blend of carbon-based waste into an EA furnace at very high temperatures the waste undergoes a complete transformation, reacting with slag and dissolving into liquid steel; thereby realizing zero waste, toxin-free recycling.
This contrasts markedly to the conventional incineration of waste plastics which generates significant toxic emissions such as dioxins and furans - - due to incomplete combustion.
The waste blend also increases the volume and “foaminess”of the slag, the key to furnace efficiency, concurrently reducing electricity usage.
The patented Polymer Injection Technology precisely calibrates an optimum waste mix. The new “green steel” process demonstrates that it is possible to absorb major waste streams in electric arc furnace (EAF) steel-making while improving furnace efficiency and, consequently, reducing electricity usage.
The incorporation of PIT into OneSteel’s commercial furnaces over the last four years has achieved a 10-20 percent reduction in coke consumption, saved millions of Kwhs of power, absorbed large amounts of waste and reduced production costs by 15-35 per cent.
The new knowledge underpinning PIT can be applied beyond steel-making to facilitate industrial scale recycling in other manufacturing processes. As of March, 2012, 1.18 million used tyres – which pose a risk of leaching toxins -- had been diverted from landfill into steel-making.
The discoveries made at high temperatures in developing PIT also promise to revolutionise e-waste recycling through novel pathways for conversion to value-added materials, bridging the gap between scientific discovery and the transformation of materials processing industries.