These points can be illustrated by example, as shown in the nickel cycle for China for 2005 (Figure 1). In can be readily seen that imports occur at every stage from mining to manufacturing, that flows into use are some forty-five times greater than the flows out of use (a signal of a rapidly growing economy), and that there exists a moderately well-established recycling chain. In actual fact, a metal cycle analysis is much more detailed than shown here, with every major product flow being determined separately, but Figure 1 suffices to illustrate some of the benefits and possibilities.
Metal life cycles can also be useful in situations where losses to the environment are known to occur but the source of the losses is undetermined. In a classic study of this type, de Cerreño et al. (2002) set out to identify and minimize mercury pollution in the New York-New Jersey harbor area. They identified the many ways in which mercury was used, and then estimated the inputs to the harbor (Figure 2). Although the error bars for the estimates were wide, it was immediately obvious that dental facilities using mercury amalgams were almost certainly the principal source. With the principal source identified, corrective measures could be considered.