Prof. Veena Sahajwalla, Director, Centre for Sustainable Materials Research & Technology, University of New South Wales (UNSW) , speaks to Swaliha Shanavas about her work on polymer injection technology for utilising used tyres to produce steel in electric arc furnace substituting coking coal in the process, the commercialisation of the world’s first ‘green steel’ manufacturing process, their recent discoveries and in particular their ‘green microfactory’ technology, and the significance of recycling and outcomes that would have profound beneficial impacts for the circular economy and environment in terms of global sustainability.
My interest in recycling and waste goes back to my childhood in Mumbai where I would see enormous piles of rubbish being sorted by the city’s poorest communities. The city, the industrial heart of India, was full of factories along highways and my interest in engineering began to develop. As I continued to study I saw a huge opportunity value to be added to the large amounts of materials already being collected in developing countries. I saw we could add a lot of value to the existing waste collection system, by creating value-added resources that would otherwise just be discarded or end up in landfill.
As Founding Director of UNSW’s Centre for Sustainable Materials Research and Technology, our team works closely with industry partners to deliver the new science, processes and technologies that will drive the redirection of many of the world’s most challenging waste streams away from landfills and back into production; simultaneously reducing costs to alleviating pressures on the environment. A key method to achieve our goals has been by using precisely controlled high temperature reactions that selectively break and reform the waste into value added green materials and products.
How significant is recycling in the context of a circular economy and the environment?
Effective recycling that sees materials reformed and re-used over and over is a driving ambition of mine. Such an outcome will have profound beneficial impacts for the circular economy and our environment in terms of global sustainability.
The scarcity of raw materials is increasing rapidly. Population increase and changes in consumption patterns combined with the inefficient use of materials push us toward a crisis point. There are many reasons for the current drive for more sustainable industrial processes, including a desire for enhanced social value, lower-energy demand, less waste, and more effective products. To achieve stable long-term growth, something will have to change—and perhaps a new approach based on the materials themselves can help. A new concept for distributed recycling based on our scientifically developed microrecycling technology can transform waste into value-added materials.
In conventional recycling, we convert like for like, using glass or plastics to make more of the same. Electronic waste (e-waste) presents a different challenge: its complex parts cannot simply be piled into a giant processing machine and converted back into their original form. Much of this waste ends up in the developing world, where regulation is negligent. A significant proportion of problematic e-waste is also landfilled and stockpiled. Our technology reforms previously used components into high value materials instead of the low value materials they usually become, or worse end up in landfill or incinerators.
What are your views on the developments in the steel industry? Why is it important for this sector to look at the use of sustainable materials in a serious manner?
As a materials engineer and Australian Research Council (ARC) Laureate Fellow who founded and directs the Centre for Sustainable Materials Research and Technology (SMaRT) at the UNSW Sydney, my work and my team’s work on sustainable materials more than a decade ago led to the commercialisation of the world’s first ‘green steel’ manufacturing process. Using recycled rubber tyres from end-of-life vehicles as part of replacement for the coal-based carbon in electric arc furnace steelmaking, we proved that carbon and hydrogen could be reformed and restructured at molecular level used directly in the process so that it could be of making steel, from these discarded objects when subjected to precise high-temperature conditions.
Our patented process required less energy, reduced the carbon emissions, and reframed rubbish as a valuable resource. It resulted in being awarded the 2017 Jubilee Professorship by the Indian Academy of Sciences. The proposition behind this discovery, with its alchemising potential to turn the estimated yearly discard of 1.5 billion car tyres into products for steel making, was really seeded from my time growing up in Mumbai, as I mentioned earlier.
What is the concept of ‘Green Steel’ and what role does it play in the ‘waste to value’ sequence?
In the early 2000s we discovered that the carbon and hydrogen contained in plastics could be used to make ‘green steel’, and replace the coke and carbon used in traditional manufacturing processes. I was awarded the 2005 Eureka Prize for the Scientific Research for this work, and it was this incredible moment to see a thought experiment I had kept in my head for so long come to fruition. The team kept telling me it worked, but I drove them mad by getting them to repeat it time after time. We then discovered that carbon could also be extracted from end of life tyres. We partnered with the steel industry and as a result this has saved millions of tyres from going to landfill but being repurposed again.
Iron- and steelmaking processes present a largely untapped opportunity to transform some of the world’s most problematic waste streams into raw materials for production. This opportunity lies in their high-temperature environments, which offer sustainable pathways for utilising chemical reactions to repurpose waste materials as resources, such as reducing iron oxide to iron and dissolving the carbon in waste materials into metal. High temperature environments can be leveraged to revolutionise the role steelmakers play in globally significant, large-scale recycling.
What are the opportunities this innovation presents to the steelmaking industry, and which are the key areas this would impact in a positive manner?
Our research focuses on carbon transformation with the goal of realizing such commercially viable opportunities to transform waste. In a practical sense, that means utilising carbon-bearing waste streams like end-of-life tyres and agricultural waste — which pose serious problems worldwide — as alternative sources of carbon.
Our commercialised polymer injection technology (PIT) is a novel recycling solution, which transforms problematic waste and reduces the cost of raw materials for the steelmaker. The new polymer-coke mix also improves the foaminess of the slag, and therefore, furnace efficiency. The concept behind this proven PIT, however, has significant potential beyond this particular case study. The opportunity for steelmakers is significantly broader. Steelmakers can transform “waste to value.”
What type of steel plants is this solution most suitable for, and why?
The green steel technology is for electric arc furnaces. However, for induction furnaces we have developed Grenew R products which include other waste materials like plastic and toner waste that can be reformed and which can then be used to diversify feedstock for manufacturing, reducing dependency on conventional materials.
What are the key challenges in adopting such technology and solutions in different countries and the implications in terms of finance and so on?
The impetus for researchers and steelmakers to innovate has probably never been greater. Globally, the cost of raw materials continues to rise, while on the sales side, pressures for competitive pricing are only intensifying. Despite the world’s ever-increasing appetite for steel, producers are under pressure globally to reduce the industry’s environmental footprint. The steel industry accounts for 3-4% of greenhouse gas emissions worldwide.
What are your key objectives for the coming years and the changes one can expect to see in these areas in the near future?
We continue to work on our recent discoveries and in particular our green microfactory technology. We launched our demonstration e-waste microfactory in April this year. This showcases a process developed by the UNSW SMaRT Centre, which transforms the components of discarded electronic items like mobile phones, laptops and printers in to new and reusable materials that can then be used to manufacture high value products.
There is no need to dump this e-waste, when it can be used to produce high value metal alloys, carbon and products such as 3D printer filament. UNSW is also finalising a second demonstration microfactory, which converts glass, plastics and other waste materials in to high value products. Mixed waste glass is used to create engineered stone products, which look and perform as well as expensive marble and granite. Wood, plastic and textile waste is used to create valuable insulation and building panels.
Our e-waste microfactory involves a number of small machines for this process and they fit into a small room. The discarded electronic devices and items are first placed into a module to break them down. The next module may involve a special robot to extract useful parts. Another module uses a small furnace to separate the metallic parts into valuable materials, while another one reforms the plastic into filament suitable for 3D printing.
A microfactory can involve one or a series of modular machines and be easily transported or relocated to where a stockpile or suitable site exists. Glass stockpiles alone amount to more than one million tonnes per year nationally. In total, Australia produces nearly 65 million tonnes of industrial and domestic solid waste each year, but it is now cheaper to import than recycle glass here. About 60 per cent of waste is reportedly recycled, but much of this is low value.
We are looking at other things too including batteries and working with individual businesses on how to develop more sustainable practices in their manufacturing processes using our technology and scientific methods.