A dynamic material flow analysis of the global anthropogenic zinc cycle: Providing a quantitative basis for circularity discussions

Accurate and up-to-date accounting of material stocks and flows is an important quantitative basis for current Circular Economy discussions. Herein, we describe the application of dynamic material flow analysis to model the global anthropogenic zinc cycle in the period 1900 to 2019 and yielding results for 1980-2019. Results show that approx. 250 Mt of zinc were globally in use in 2019, which equals the 19-fold mine production of the same year. Between 2010 and 2019, 34 Mt of Zn in fabrication and manufacturing scrap (new scrap) and 77 Mt of Zn in end-of-life products (old scrap) became available for recycling. Of these, approx. 52 Mt of zinc were recycled, the majority (42 Mt) via direct reuse in production processes and a smaller part via refineries. The recycling input rate of 29% and the end-of-life recycling rate of 27%, both averaged between 2010 and 2019, point to opportunities for increased circularity. Nearly half of the overall cycle losses occur in the end-of-life waste collection, so that measures for more circularity should be taken at this lifecycle phase. Further considerable zinc losses arise within steel recycling, where zinc transfers to steel mill dusts. These dusts are more and more used for zinc recycling, but still underutilized. Despite existing recycling challenges, the overall modeling results show that recycling flows and recycling rates rose in the last decade.