Time-dependent material flow analysis of iron and steel in the UK: Part 2. Scrap generation and recycling

This paper presents an analysis of the use of iron and steel in the UK and explores how much of the iron and steel is recycled when it becomes obsolete after use. The first part of this paper series investigated production and consumption trends of iron and steel in the UK, whereas this paper focuses on scrap generation and recycling. Information on the amounts of iron and steel going into different groups of goods, together with values for their estimated lifetimes, have enabled modelling of the annual release of iron and steel from the use phase in the form of end-of-life scrap. This is an application to material flow accounting of the theory of residence time distributions used routinely in chemical reaction engineering. By comparing modelled generation of scrap with actual scrap consumption in the UK, we obtain estimates of loss or accumulation of iron and steel scrap in the UK. The model indicates that as much as 30% of the scrap that was potentially available in 2001 as end-of-life scrap has either been accumulated within the economic system or lost to landfill.