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U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

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Lead Reclamation From Superfund Waste

From Tech Trends June 1996

Lead Reclamation From Superfund Waste

By Laurel Staley, National Risk Management Research Laboratory

Materials from three Superfund sites, a construction site and a bridge sandblasting operation were processed with regular feed to a secondary lead smelter as part of an EPA Superfund Innovative Emerging Technology Evaluation. Since secondary lead smelters already recover lead from recycled automobile batteries, it seemed likely that this technology could be used to treat waste from lead-acid battery contaminated Superfund sites. Such sites are very widespread and constitute a significant problem in site remediation.

In general, the EPA evaluation demonstrated that secondary lead smelters can treat lead contaminated wastes from Superfund sites provided that the waste is reduced to the right size (less than 1/4 inch) and is not fed too quickly (at more than 50% of the smelter feed rate). Waste feed combinations of between 1% and 45% can be successfully fed into the secondary smelter. Lead waste was reclaimed from all test materials over a range of efficiencies, from an estimated 70% for the abrasive blasting material to 99.5% for NL Industries site wastes, which consisted of lead slag, debris, dross, ingots, battery case pieces, baghouse bags, pallets and cans, which had initial concentrations of 20% to 57%. Initial lead concentrations for iron shot bridge-blasting material, rubber and plastic battery cases, with some soil and demolition debris coated with lead paint ranged from 3.2% to 14.7%.

The cost for remediating lead-acid battery sites using this technology ranged from $35/ton to $375/ton based on a variety of factors such as lead concentration, market price for lead, distance from the smelter, percent of test material that becomes incorporated into the final slag, iron content, BTU value of the test material and sulfur content.

The first step in reclaiming lead from Superfund wastes is acquiring and transporting the material to one of the smelters. Pre-processing includes screening to remove soil, large stones or non-contaminated debris that cannot be processed through a secondary smelter. Larger debris (>12 in.) is also removed because large material tends to remain unburned in reverberatory furnaces.

Material is blended with typical feed prior to processing through the furnaces. Typical blend ratios range from 10% to 50% by weight, based on treatability tests and other factors, such as lead, sulfur, iron or ash content.

Smelters typically contain tandem reverberatory/blast furnace processes. The lead-containing material that is to be reclaimed is first charged to the reverberatory furnaces. They process the feed material into slag, which typically contains 60% to 70% lead and a soft (pure) lead product.

The reverberatory furnace slag is enhanced by processing it through a blast furnace. Iron and limestone are added as fluxing agents to enhance furnace production. The blast furnaces are tapped continuously to remove lead and intermittently to remove the slag. The blast slag, is transported to an offsite landfill for disposal.

Lead produced in the blast and reverberatory furnaces is transferred to the refining process where metals are added to make specific lead alloys. The lead is then pumped to the casting operations where it is molded into ingots for use in the manufacture of new lead-acid batteries.

For more information, call Laurel Staley at EPA's National Risk Management Research Laboratory at 513-569-7863.


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