Recycling Waste Plastics for Slag Forming in EAF Steelmaking

Slag foaming
Plastics have great value in our daily life because of their convenience, low manufacturing cost and durability. However, due to the ubiquitous nature of their use and their relatively short life span, the disposal of plastics has become a serious environmental problem. Currently, the disposal of waste plastics is handled in a few ways: landfill, incineration and recycling (this option remains limited) . Landfill and incineration options are not environmentally viable.
 
The waste plastic in municipal solid waste amounts to ~10%, plastics have a fairly high volume-to-weight ratio, and do not biodegrade in landfill conditions. Also the formation of methane gas in landfill sites is a significant contributor to overall methane emission levels. The second alternative, incineration of waste plastics, often generates hazardous environment pollutants.
 
In response, Professor Veena Sahajwalla and her research team in the School of Materials Science and Engineering have shown that plastics could become a valuable resource in EAF steelmaking. Carbon based polymers can be effectively utilised to produce ‘slag foaming’ – (a chemical reaction of significant importance in EAF) and thus have the capability to partially replace coal/coke which is conventionally used.
 
Research in the laboratories has shown that mixtures of coke and various plastics were successful in causing slag foaming. The aim of this study is to shed light on the fundamental science underlying the use of the different types of plastic in EAF steelmaking. Findings from this experiment could be significant in paving the way for innovative utilisation of waste plastic in EAF steelmaking.
 
 
Slag foaming as a function of time for 70%coke- 30%plastic residue/slag system at 1550°C
 
Research on recycling of waste plastics in steelmaking process has received one of the 2005 “Eureka Prize for Scientific Research” given for outstanding curiosity-driven scientific research by an Australian scientist under the age of 40.
 
Members of Sustainable Materials Processing Program:
N.Saha-Chaudhury, Rita Khanna, Sushil Gupta, M. Amin, Pedro Yunes, Tsuey Cham, Mihaela Grigore, Sihyung Lee, Byong-chul Kim, Pramod Koshy, Muhammad Rahman, Kelli Kazuberns, Fuhai Liu, Trilochan Gill, Magda Zaharia, Muhamad Ikram, Jonathan Dicker, Sharifah Shahnaz, Dean Kennington, Tanaka and Fernando Collazo.
 
Professor Veena Sahajwalla
Director of Sustainable Materials Processing Program