The Use of LCA for the Environmental Evaluation of the Recycling of Galvanised Steel

摘要

Life Cycle Assessment has been used to compare the environmental performance of landfilling of the zinc used for galvanising steel with recycling by a number processes. Hypothetical process routes were composed involving three different EAF dust treatment processes, Waelz kiln, DC-furnace, and EZINEX, as well as scrap dezincing. The study shows that recycling of zinc used for galvanising steel clearly has environmental benefits in that it saves zinc resources. However, zinc recovery does not necessarily decrease the potential impact on global warming and acidification. The magnitude of these two impact categories is tightly correlated with the amount and type of primary energy consumed in a process. Due to the high electricity consumption in the dezincing process, this route has the highest impact on Global Warming Potential as well as Acidification Potential. The major part of the energy requirement for the production of zinc from primary and secondary sources is consumed in the reduction of ZnO to Zn.