Mumbai-born scientist Professor Veena Sahajwalla, Director has invented Polymer Injection Technology that converts old rubber tyres to metal alloys that make ‘Green Steel’ says this could be the answer to deal with the growing problem of disposal of waste tyres globally.
Every year, over one billion tyres are manufactured worldwide, and equal number of tyres are permanently removed from vehicles, becoming waste.
U.S. is largest producer of waste tyres although increases in new vehicles sales in China and India are rapidly contributing to waste tyre volumes.
Although modern tyres are fundamentally rubber products, they are a complex mix of natural and synthetic rubbers, and various structural reinforcing elements including metals and chemical additives.
This complexity has led to stockpiling, dumping and diversion to landfi ll. This has exposed communities to environmental and health risks and has squandered valuable resources locked up in tyre dumps.
Stockpiled tyres are at risk of fi re and toxic smoke, the largest tyre fi re in the world began in Wales in 1989 at Heyope, where 10 million tyres had been dumped, and took 15 years to extinguish.
Other risks include the stagnant water in tyres that provides breeding grounds for mosquitoes and leaching of toxic substances into soils.
India’s waste tyres account for about 6-7% of the global total. With the local tyre industry growing at 12% per annum, waste volumes are rising.
India has been recycling and reusing waste tyres for four decades, although it is estimated that 60% are disposed of through illegal dumping.
Despite this, India is the second largest producer of reclaimed rubber after China. In 2011, India produced 90,000 metric tonnes of reclaimed rubber from waste tyres.
By 2016, some100 000 kms of Indian roads had been laid with asphalt blended with recycled rubber, and over 500 000 tonnes of crumb rubber modifi ed bitumen (CRMB) is used annually in road construction.
New regulations in 2016 allow for import of waste tyres for recycling.
Polymer Injection Technology (PIT) or ‘green steel’ introduces a simple modifi cation into the conventional manufacturing process for steel. The technology precisely controls the injection of granulated waste tyres in conventional Electric Arc Furnace (EAF) steelmaking, partially replacing non-renewable coke.