| Popis: |
Publisher Summary The magnitude of the world's annual needs for newly mined substances has grown so large that it is difficult to view the volume in perspective. The annual per capita consumption of newly mined mineral products for all the peoples of the world now totals 3.75 mg. The total includes coal, oil, iron, copper, cement, and a myriad of substances used in countless different ways: the total is still rising, doubling approximately every decade, and there is no sign that it is likely to stop in the near future. Whichever way one anticipates the use of geochemically scarce metals in the future, it is clear that there are very real limits to the amounts available in traditional ore deposits of the continental crust. Efficient recycling, which surely must come as existing deposits are worked out and new ones become harder and harder to find, will guarantee that even the scarcest metals will always be available in at least small amounts. Nevertheless, recycling can at best sustain a declining use rate. While growth or even level use rates pertain, newly mined material must continue to be added. |
