Traded metal scrap, traded alloying elements: A case study of Denmark and implications for circular economy

Since metals are often used in alloyed forms, proper management and efficient recycling of metal scrap is key to sustainable management of those alloying metals as well. Previous studies on the trade of metals and metal containing products focused mainly on the carrying major metals themselves, however, the quantity and type of their embodied alloying elements remain rarely investigated. In this paper, we aim to address this knowledge gap by compiling an alloying element composition database for scrap of three bulk metals (iron and steel, aluminum, and copper), and using Denmark, a typical industrialized country with a high share of metal scrap export, as an example. Our results show that most alloying elements embodied in bulk metal scrap exported from Denmark depict a fluctuating yet overall increasing pattern from 1988 to 2017. While alloying elements embodied in steel scrap such as chromium and nickel and the construction sector contribute the most to the total embodied alloying elements, other alloying elements such as cobalt, bismuth, vanadium, titanium, and niobium with a lower amount yet a high market value and criticality status deserve a closer look as well. We conclude that further investigation on how the trade of metal scrap affect the recycling pathways and efficiencies of alloying elements are needed to support discussion on global and regional resource management and circular economy strategies.