The “Hidden” Trade of Metals in the United States

The “Hidden” Trade of Metals in the United States
Jeremiah Johnson
T. E. Graedel
Journal of Industrial Ecology, Volume 12, Issue 5, Pages 739–753

The transport of ore and refined metals into and from countries has long been quantified, both because of its financial implications and because of the relative ease of tracking those flows. This information says little, however, about the net trade of metal in all its forms, particularly “semiproducts,” such as sheet and wire, and metal in traded products (MTP). A comprehensive analysis for the United States for copper, lead, zinc, chromium, and silver, in which all trade flows are included, demonstrates that MTP flows can often be a large factor in determining a country's import/export dependence, accounting for between 13% (zinc) and 57% (silver) of traded metal in all forms. A methodology was created to calculate the end user net import reliance, which is the net import of metal contained in ore, concentrate, refined forms, and semi‐manufactured and finished products, plus any releases of metal from government or producer stocks, as a function of the flow of metal into end use by consumers. For all five metals, this calculation showed a higher reliance on imports than calculations that solely examine ore, concentrate, and refined metals. This suggests that the metal contained in semi‐manufactured and finished products increases U.S. material import vulnerability. However, the in‐use stocks of these metals contained in products may serve as a potential resource, serving to mitigate this vulnerability. Graphical representations of metal trade in all forms by geographical origin and destination are provided to characterize the nature of the trade and provide information that would be useful in characterizing U.S. import vulnerability.

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