Methods to Evaluate Environmental Aspects of Materials

This chapter introduces Life cycle assessment (LCA) as it can be used in connection with metals. Rather than stressing the connection of LCA with ISO standards, it evolves the methodology from its historical origins, chemcial engineering and accounting, and discusses it applicability to material specific issues. Beyond the obvious success of LCA and its wide appeal, especially in decision making circles, the approach is still a methdology in the making with some weak points, which need more elaboration. Some directions in which to search for such an evolution are outlined. MFA is used as a tool for two primarily objectives. One is to characterize material cycles for natural resource conservation. The enhancement of material recycling and the reduction of the size of the final sink are part of the objective of natural resource conservation. Characterizing the overall picture in terms of material flow is useful for understanding patterns of resource use and losses of material to the environment. In the second primary objective, MFA is used for risk assessments of substances. MFA helps to clarify where substances originate, what channels they follow, and what agents are at work in the overall life cycle of a substance, from the mining to the final sink. An MFA analysis could target either all of the substances involved in a given space or could be limited to one or more material(s) and substance(s) in a given space. Focusing on the total amount of all substances, as in EM- MFA, provides useful information, and analysis of a specific substance provides different, and also useful, information. The static and dynamic approaches to conduct MFA are expounded. In addition, two measures for estimating the material stock: bottom-up approach and top-down approach, are also interpreted. Recent progresses in MFA case studies, such as future demand prediction, issues in metal recycling, and MFA on minor metals are introduced.