Stocks and flows of copper in the US: Analysis of circularity 1970-2015 and potential for increased recovery

An analysis of the copper life cycle in the U.S. was performed to investigate the circularity of copper from 1970 to 2015. A stocks and flows model for copper was developed for the major life cycle phases by collecting extensive primary data from government and private sector sources, via available data and surveys and interviews with individuals within companies, government, and other organizations. The data were integrated into a stocks and flows model. Collection and inclusion of primary end-of-life data into the model represents a contribution of the material flow analysis presented and provides insight into specific limitations and opportunities for improving the circularity of copper. The analysis incorporates 45 years of data, providing historical context and insight into changing trends. A number of key findings emerged from of the stocks and flows analysis. First, end-of-life collection is a complicated ecosystem. The largest stock accumulation of copper is in the use phase-on the order of 72 million tons since 1970. Over half of this is in buildings and construction, an order of magnitude more than the total accumulation in any other part of the copper life cycle. The analysis also revealed that while there are losses of copper via process losses, degradation, and tailings generation, exports (much of which are unaccounted for as embedded flows) and hibernating stock are much more significant losses from the U.S. circular economy. Finally, building and construction and electric/electronic products are the two use phases where improved collection and recycling would yield the most impact to improving circularity of copper since they together comprise more than 80% of total accumulation.