Towards comprehensive assessment of mineral resource availability? Complementary roles of life cycle, life cycle sustainability and criticality assessments

摘要

Regarding mineral resources, there is ambiguity around concepts such as scarcity, rarity, criticality and depletion and associated assessment methods. This paper investigates three method groups: life cycle impact assessment (LCIA), criticality assessment and life cycle sustainability impact assessment methods. The aim is to clarify how these method groups and concepts relate and their potential roles in a comprehensive mineral resource availability assessment. The study finds that their modeling approaches and practical implementations are sometimes misaligned with what they aim to assess. This results in similarities between methods from different method groups. Some LCIA-methods include elements which belong to criticality assessment, which could explain some of the ambiguity. A reason for misalignment is a lack of distinction between mineral resource stocks, funds and flows. The lack thereof also results in invalid impact pathway cause-effect chains and imprecise terminology allowing for misunderstandings in the "resource debate". Distinguishing between mineral resource stocks, funds and flows resolves misalignments within methods and between method groups and, in turn, ambiguity around concepts such as scarcity, rarity, criticality and depletion. It follows that long-term scopes need to include assessments of depletion of ecospheric stocks. Methods focusing on factors which represent or can influence magnitude and location of technospheric flows are suitable for short term scopes. Different types of technospheric funds, such as resources in active use, end of life products and landfills, can be relevant in short, medium and long-term scopes. Altogether, assessments of stocks, funds and flows are complementary parts of a comprehensive mineral resource availability assessment.