Publication

Criticality can be defined as “the quality, state, or degree of being of the highest importance”, but how can we understand what is meant by “highest importance”? In this chapter we define and describe a multi-parameter approach to the criticality issue that involves (as do the efforts of other researchers and governments) a variety of geological, economic, technological, environmental, and social concerns. Our results suggest that the highest level of concern should be for metals whose processing and use involves extensive separation from parent ores, high levels of embodied energy, little opportunity for substitution, and low levels of recyclability. Improved approaches to material use should thus involve the preferential utilization of non-critical materials, attention to the potential for material reuse at the design stage, and a focus on increasing the efficiency of recycling.