Innovative use of recycled polymer in sustainable EAF steelmaking

In Electric Arc Furnace (EAF) steelmaking, carbon materials, such as anthracite and coke, are typically added as slag foaming agents and also as carburisers. With the ever increasing requirement to reduce cost by reducing material and energy consumption and also by increasing productivity, there has been a growing need to search for alternative carbon materials. Recycled polymers, such as end-of-life rubber tyres and municipal waste plastics, are a good source of alternative carbon materials for steelmaking. Not only will recycled polymers offer a low cost source of carbon materials, but will also greatly assist in providing a sustainable solution to the ever growing worldwide challenge of disposal of these waste polymers. OneSteel, an Australian manufacturer of long steel products, have been focusing on developing innovative process and engineering technologies to use recycled polymers as alternative carbon materials in steelmaking. In close collaboration with the University of New South Wales, OneSteel has developed and commercialised a technology known as the Polymer Injection Technology, which enables EAFs to inject blend of rubber crumb from waste tyres and coke as carbon injectant for slag foaming. The main benefit of injecting rubber/coke blend in place of 100% coke is the improved slag foaming and improved slag reduction, which result in reduced electrical energy consumption, improved productivity and increased yield. Polymer Injection Technology has become a standard process at OneSteel's EAF plants in Sydney and Melbourne. OneSteel has also successfully commercialised the Polymer Injection Technology in UMC, Thailand, SeAH Besteel, Korea and Celsa UK. OneSteel is currently working with a number of EAF plants worldwide for possible implementation of Polymer Injection Technology. OneSteel has also been developing an engineering technology to manufacture composite materials called the Polymer Composite Briquette. The composite briquettes can comprise of recycled materials including carbon fines, plastics and iron containing materials such as millscale, for use as carbon and iron units in EAF steelmaking. A series of EAF plant trials have been completed in Sydney and Melbourne using the Polymer Composite Briquette as charge carbon in place of traditional nutcoke. The results have shown considerable benefits in increased carbon recovery efficiency, reduced electrical consumption and improved productivity. OneSteel is currently in the process of developing commercial scale manufacturing capabilities for the Polymer Composite Briquette.