Editing Lead (section)

=== Secondary ===
{{Further|Battery recycling#Lead–acid batteries}}
Smelting, which is an essential part of the primary production, is often skipped during secondary production. It is only performed when metallic lead has undergone significant oxidation.{{sfn|Thornton|Rautiu|Brush|2001|p=56}} The process is similar to that of primary production in either a [[blast furnace]] or a [[Rotary kiln|rotary furnace]], with the essential difference being the greater variability of yields: blast furnaces produce hard lead (10% antimony) while reverberatory and rotary kiln furnaces produce semisoft lead (3–4% antimony).{{sfn|United States Environmental Protection Agency|2010|p=1}}

The [[ISASMELT]] process is a more recent smelting method that may act as an extension to primary production; battery paste from spent lead–acid batteries (containing lead sulfate and lead oxides) has its sulfate removed by treating it with alkali, and is then treated in a coal-fueled furnace in the presence of oxygen, which yields impure lead, with antimony the most common impurity.{{sfn|Thornton|Rautiu|Brush|2001|p=57}} Refining of secondary lead is similar to that of primary lead; some refining processes may be skipped depending on the material recycled and its potential contamination.{{sfn|Thornton|Rautiu|Brush|2001|p=57}}

Of the sources of lead for recycling, lead–acid batteries are the most important; lead pipe, sheet, and cable sheathing are also significant.{{sfn|Thornton|Rautiu|Brush|2001|p=56}}