Recycled Content for Metals with Refined Classification of Metal Scrap: Micro-Level Circularity Indicator in Accordance with Macro-Level System

Transitioning from a traditional linear economy to a circular economy occurs at the micro-level system, encompassing products and companies, which should be monitored. For metals, recycled content as an input-side indicator of recycling quantifies the ratio of metal scrap consumed during production and fabrication. However, conventional methodology struggles to evaluate recycled content uniquely due to the ambiguous classification of new scrap derived from industrial processes. Additionally, the input and output of new scrap between micro-level systems are often inadequately counted, causing inconsistencies in the recognition of secondary input between macro- and micro-level systems. This study introduces a refined classification for metal scrap, precisely distinguishing new scrap by its originating processes. Furthermore, we propose a novel perspective on new scrap, viewing it as a mixture of old scrap and primary raw materials, with only the portion of old scrap being considered secondary raw material. This stance navigates past the binary classification—whether new scrap should be classified as secondary—eliminating ambiguity and allowing for clear identification of secondary raw materials. The developed methodology ensures that all inputs of scrap are accounted for without leakage, and the recycled content of a specific metal is uniquely determined, maintaining consistency with macro-level systems.