Impact of China's waste import policy on the scrap copper recovery pattern and environmental benefits.

The international trade weight of scrap copper has exceeded 6 million tons annually over the past two decades. China introduced the "National Sword" policy in 2017, which brought uncertainty to the international recycling of scrap copper. We use the international scrap copper trade figures from 1998 to 2019 in UN Comtrade, and seek to analyze the impact of China's import ban by setting up a difference-in-differences (DID) model based on the gravity model. The results show that 1) The ban has promoted the development of regional trade and improved the quality of scrap copper in international trade. The unit value of imported scrap copper in China has risen by 58%. 2) China's import ban has reduced the import weight of scrap copper by 68.6% and its value by 44.4% without the influence of other socioeconomic factors. 3) China's import of copper scrap is concentrated in coastal provinces. Guangdong Province has been most heavily affected. The imports of low-quality copper scrap in Guangdong have decreased by 94%. 4) The import ban reduced the environmental impact in China by 36.6%, but the global environmental impact has increased because of the gap in recycling technology, especially in developing countries. These discoveries will be beneficial to predict the future of international scrap copper recovery, and help rule makers formulate trade and environmental policies.