Metals are also uniquely suited to conduct heat (heat exchangers) and electricity (wires), functions that are indispensable to industrial economies. Their strength makes them the preferred material to provide structure, as girders for buildings, rails for trains, chassis for automobiles, and containers for liquids. Industrial society values metals for their many useful properties. Although the practice of recovering metals for their value dates back to ancient civilizations ( 1), today the protection of Earth's resource endowments and ecosystems adds to the incentive for recovering metals after use. Inefficient recovery of metals from the economy increases reliance on primary resources and can impact nature by increasing the dispersion of metals in ecosystems.
Society can draw on metal resources from Earth's crust as well as from metal discarded after use in the economy. Metals play an important part in modern societies and have historically been linked with industrial development and improved living standards. Only through a concerted effort can society recover a maximum amount of metal from the industrial/social system to benefit the environment. Industry must develop better technology to isolate and recover maximum value from metals in waste streams, and governments must institute policies that remove barriers to their economically and environmentally sound recovery. Environmental regulation also affects secondary metal production through laws that control emissions and govern the classification and treatment of metal-loaded wastes. A variety of technologies are used to recover and process metals from waste streams and their use for metal production influences the amount of secondary metal that reenters the system. The environmental benefits of increasing reliance on secondary metal production include conserving energy, landscapes, and natural resources, and reducing toxic and nontoxic waste streams. Secondary sources include all metals that have entered the economy but no longer serve their initial purpose.
▪ AbstractSociety uses metals derived from primary and secondary sources.