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 4. Production of basic metal free of impurities

 (e.g., making of pig iron or "hot metal")

 5. Production of alloys

 6. Fabrication of implements

 7. Use of final products until worn beyond

 serviceability or outmoded

 8. Disposal of used implements

 9. Collection of scrap metals

 10. Reuse of scrap metals as raw material inputs

 The first five steps outlined above are concerned

with the conversion of unmined metals to metals in use.

They are most directly concerned with the provision of

new metals required for further expansion of the stock

of implements in use and for the replacement of metals

lost through waste or wear. Steps six through ten

involve metals use and reclamation.

 The rate at which new metals must be acquired

ultimately depends upon the rate of expansion of the

stock of metals in use and upon the rate at which

metals in use are lost through wear or discard. If the

stock of metals in use is to be maintained, the rate

at which new metals are added must at least equal the

rate at which they are lost. Therefore, the need for

new metals is increased by loss of metals through wear

or discard; it is lessened to the degree that metals in

use are retained.