Dynamic material flow analysis of rhenium in China for 2011–2020

Rhenium (Re) is one rare and heavy metal element that plays an important role in various fields, such as aerospace applications, petroleum industry, and power generation. However, less attention has been paid to its metabolism patterns. This study employs a dynamic material flow analysis method to investigate the anthropogenic Re cycle in China from 2011 to 2020. The results show that the annual demand for Re had increased from 7.02 tons to 10.41 tons during the study period, in which 44.91% of the total Re was used to produce petro-reforming catalysts and 32.87% of the total Re was used to make aero-engines. A total of 54.94 tons of Re became in-use stock and 18.55 tons were discarded. A significant Re loss (55.92 tons) was generated in the refining and separation stage, mainly due to cost and technological constraints. On the supply side, the domestic primary Re production remained stable in China, but unable to meet the market demand. Therefore, China has to rely on importing Re products, with a net import reliance (NIR) of more than 75% in recent years. The imported Re had increased from 8.68 tons in 2011 to 18.99 tons in 2020. About 85.4% of the imported final products were aero-engines. By identifying several problems hindering the sustainable use of Re in China, we proposed several policy recommendations to improve the overall Re resource efficiency, such as policy and economic supports for Re recycling, enhancing Re's production and utilization technologies, and strengthening Re supply resilience.