Life cycle assessment of steel production from iron scrap: a case study at a steel plant

Background and Objective: The steel industry is the world's largest consumer of energy. A large amount of iron waste is produced annually, which its use in the steel industry can be economic. The purpose of this study was to investigate the environmental impacts of the steelmaking from iron scrap as a raw material using a life cycle assessment (LCA) method. Materials and Methods: Simapro software and the ecoinvent database were used to conduct LCA. Data on the steel production process (raw materials, waste, and products) were collected by a questionnaire from a steel plant. Environmental burdens were quantified using ReCiPe, Cumulative Energy Demand (CED), IPCC) Intergovernmental Panel on Climate Change) and water footprints methods. Results: The results of the ReCiPe method showed that the terrestrial ecotoxicity with a value of 14392 kg 1,4-Dichlorobenzene (1,4-DCB) eq/ton of steel and global warming with 5289 kg CO2 eq/ton of steel, had the greatest environmental impact, respectively. The lowest environmental impact of this process was obtained for freshwater ecotoxicity and human carcinogenic toxicity. The carbon footprint resulting from steelmaking is 5.24 ton CO2 eq/ton of steel. The most important sector of the greenhouse gas producer is the consumption of electricity with a rate of 2900 of kg CO2 eq/ton of steel. The cumulative energy demand of one ton of steel ingot was 73393 MJ, which is three times the global equivalent. The total water footprint for one t of steel was 19.5 m3 of water, which is almost near to the equivalent in Europe. Conclusion: the use of iron scrap as raw material in the process of steelmaking instead of iron ore has reduced the amount of human toxicity potential and mineral resource consumption.