Doe Run has agreed with the US Environmental Protection Agency (EPA) to close its existing primary lead smelting and refining operations at Herculaneum in Missouri, USA, by the end of 2013. The plan is to replace the current operations with a new plant employing new hydrometallurgical technology that uses a wet chemical process to selectively dissolve lead concentrates into solution and then extracts lead from the solution using an electric current. This 'electrowinning' process has been developed with Engitec as partners and is similar to the technology used in the recovery of other metals, but has not before been applied to lead. The decision to switch technology has been driven by the tighter lead-in-air emissions standards due to come into force in the mid-2010s (lead in air standard moving from 1.5 mu g/m~3 to 0.15 mu g/m~3). Doe Run has agreed to a refined lead production limit of 130,000 short tons per year (118,000 metric tonnes per year) to limit sulphur dioxide emissions at its existing plant until its eventual closure. Herculaneum is likely to produce around 110,000t of refined lead in 2010 and a similar amount in 2011.
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