Dynamic analysis on material balance of copper and copper-alloy scraps in Japan

The recovery of metal scrap for recycling contributes to the conservation of natural resources and the construction of a sound material cycle. A dynamic material (substance) flow analysis is useful to understand how and in what proportion materials are used, how they may dissipate into the environment, and how they partition into certain reservoirs (e.g. landfills). So, it enables us to investigate the potentials of metal scrap recovery in the designated area in the future. In this article a dynamic material flow analysis for copper and its alloys in Japan was conducted in order to estimate the stock, the amount of discarded and collected scraps in the future. There was a significant gap between the supply and the demand of scraps in statistics in Japan. The comparison between the estimation and the statistics suggested that this gap was due to the obsolete scraps which were not accounted as a supply of collected scraps. The amounts of collected copper scraps and its alloy scraps were estimated separately from 19702005. The results showed that approximately 300 thousand tons of high-purity copper or high copper alloys were recovered with impurities or copper-alloy scraps, which were finally consumed as copper-alloy scraps.