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Lead


Photograph of large lead shot


Lead is a heavy, soft, relatively inexpensive metal ($116 a ton in 1940) which in ancient times was a byproduct of silver mining.  Lead found uses in plumbing and other applications where its easy workability and resistance to corrosion are valuable. A very dense metal (11.34 g/cm, about half again as dense as iron), it also found use as a ballast and, later, as a component of small arms bullets. Lead was also put to use in low-melting alloys, as a gasoline additive, in storage batteries, and in many other applications, so that primary lead production became the most important source of the metal.

Lead usually occurs as galena (lead sulfide), which is easily refined by first roasting the ore to remove the sulfur, then smelting with carbon to remove oxygen, leaving a mixture of lead and other metals. This is purified by skimming off the copper that rises to the top, then adding zinc which extracts any silver or gold before it, too, rises to the top to be skimmed off. The valuable gold and silver are recovered by boiling off the volatile zinc. The pure lead was often alloyed with antimony or copper to increase its hardness.

Compounds of lead are quite toxic, and because the body has difficulty ridding itself of lead, it is a cumulative poison.  Today safer alternatives have been found for most traditional uses of lead.

Lead was not a serious limiting resource for the Allies, though wartime demand was so great (including as a substitute for scarcer resources) that there were occasional shortages. The United States produced considerable lead from mines in Missouri, and there were also large deposits in Australia and smaller deposits at various locations in the western United States, including AlaskaJapan produced less than 10% of its requirements of lead in the home islands, so that this metal was among the depressingly long list of essential industrial materials that had to be imported.  The seizure of Burma, an important lead producer, eased the situation only to the extent that shipping was available to get the lead back to Japan.

Lead mines in the Pacific

Bawdwin

Bingham Canyon
Broken Hill
Butte
Coeur D'Alene
Galena
Lashio
Mount Isa
Pioche

References

Cohen (1949)

Klein (2013)

Van Royden and Bowles (1952)

U.S. Geological Survey (accessed 29 December 2006)

 


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