Evolution of the anthropogenic chromium cycle in China

Abstract

AbstractChromium (Cr) is a critical metal due to its essential economic importance and potential supply risk in contemporary society. Recycling of secondary chromium metals is a desirable sustainable strategy in responding to the soaring demand, but existing literatures have limitations in capturing the anthropogenic chromium cycle and thus fail to address the availability of such secondary resources. Under such a circumstance, this study aims to uncover China's chromium dynamic flows and stocks for the period of 2000–2019. The results show that China's chromium demand increased more than tenfold from 2000 to 2019 due to the rapid development of the stainless‐steel industry. The net Cr import to apparent Cr consumption (includes old scrap recycling) reached 94% in 2019, in which 69% of purchased virgin materials were imported from the African region (e.g., South Africa). The generation of end‐of‐life flows has been accelerating since 2000 and reached approximately 1,400 Gg in 2019, indicating more available secondary Cr resource and great recycling potential. However, the end‐of life recycling ratio (EOL‐RR) fluctuated during 2011–2015 and decreased to about 17% (uncertainty ranging from 7% to 24%) in 2019. Such findings reflect the unstable demand for old scrap and call for an integrated management of both primary and secondary chromium resources, with a special focus on accurate planning for scrap utilization. Possible solutions include the reengineering of sorting and processing for stainless‐steel scrap, the development of secondary resource markets, economic incentives for secondary resources, and the increased imports of secondary stainless‐steel materials.