System Approach and Metrics for Determining Steel Recovery from End-of-Life Infrastructures: Case study road and rail infrastructures
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Producing steel from scrap has several environmental benefits compared to producing steel from virgin iron ore. Studies show that the energy consumption by secondary route to produce one ton of crude steel is between 9.1 and 12.5 GJ/tcs which is much less than the energy intensity of primary production routes. As Europe is facing with the lack of local raw materials to produce steel as well as its continuous efforts to implement climate policies, the share of secondary production has a good potential to increase in European steel industry which in turn will improve the scrap industry. However, studies show that, recently, consumption of steel scrap is reduced by European steelmakers and only a fraction of the steel in products reaching obsolescence is actually recovered, while the reasons for this inefficiency is still poorly understood.This research was conducted using Material Flow Analysis (MFA) framework to investigate the efficiency of steel recovery and recycling in European transport infrastructures, specifically railway tracks and railway bridges of UK in 2012 and road bridges of Norway in 2008. A set of metrics defined to quantify this efficiency by considering obsolete stock, reuse and trade which are omitted in the other studies. Although, model results at regional level showed that almost all stages of steel recovery and recycling are working efficiently in both regions, there is a remarkable inefficiency in obsolete stock in terms of dismantling and demolition. Cost, regulations and accessibility in terms of both location of structure and obsolete stock data are recognized as the main reasons of this inefficiency in this research and possible solutions are presented.