Decoupling Status of Metal Consumption from Economic Growth

The decoupling statuses of the consumption of 22 kinds of metal with economic growth were analyzed. Metals were Fe, Al, Cu, Cr, Zn, Mn, Pb, Ni, Co, Sn, Sb, Si, Mo, W, Li, In, Ga, Ag, Au, Pt, Pd and rare earths. The relations of the annual consumption per capita of each metal to GDP per capita were approximated into two steps of liner formulas; yM=aM, 1 X (X cM), where yM is the annual consumption of the metal M per capita, X is GDP per capita. The metal which has only single relation of yM=aM, 1 X was judged to stay in the state of coupling. When aM, 1>aM ,2, the state was judged to be decoupling. Furthermore, it was judged to be the status of an absolute decoupling when aM, 2<0. The metals which have attend to absolute decoupling are Au, Sn, Zn and W. Cu and Pb are at the border of the absolute decoupling. While Fe, Al, Ni, Mo, Sb, Ag, Pd are decoupling to GDP per capita, Si and Pt are still in the status of the coupling with economic growth. In the case of Co, Li, In, Ga and rare earth, new coupling relation with economic growth have developed in these several years.