Beneficial Uses of Spent Foundry Sands

The metal casting industry generates spent foundry sands. Foundries purchase new, virgin sand to make casting molds, and the sand is reused numerous times within the foundry. This reuse eventually renders the sand unsuitable for use in casting molds, and a portion of the sand is continuously removed and replaced with virgin sand. The spent foundry sand is either recycled in non-foundry applications or landfilled.

In 2007, the American Foundry Society estimatedExit that less than 30 percent of the 10 million tons of spent foundry sands generated annually are recycled. EPA believes a greater percentage of spent foundry sand can be safely and economically reused.

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Beneficial Uses for Spent Foundry Sands

EPA's risk assessment for the beneficial uses of spent foundry sands found that that silica-based spent foundry sands produced by iron, steel and aluminum foundries can be safely reused to save energy, reduce the need to mine virgin materials, and reduce costs for both producers and end users. EPA supports the use of silica-based spent foundry sands from these foundry types in the following applications:

  • As an ingredient in manufactured soil;
  • As an ingredient in soil-less media (potting soil); and
  • As a foundation layer of roads (subbase).

EPA estimates that approximately 2.6 million tons of spent foundry sand is beneficially used outside of foundries annually, with iron, steel and aluminum sands representing 96 percent of the foundry sands that are beneficially used. Currently, only about 14 percent of those sands are beneficially used in soil-related applications. EPA believes that there is potential for substantial beneficial use market growth and increased environmental benefits for the applications studied in the 2014 risk assessment.

Foundries and foundry sand recyclers should consult state regulators to ensure that planned uses are consistent with state beneficial use and waste management programs and that the chemical and physical properties of the sand meet applicable state environmental limits, engineering performance criteria and other state requirements.

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Regulations for the Beneficial Use of Spent Foundry Sands

The Resource Conservation and Recovery Act (RCRA) encourages environmentally sound materials management practices to maximize the use of recoverable materials and foster resource recovery. The EPA strives to motivate behavioral change to improve materials management through both regulatory and non-regulatory approaches. The EPA’s primary role in non-hazardous solid waste management, including evaluating beneficial uses, is providing national leadership and technical assistance. Under RCRA, non-hazardous solid wastes, including non-hazardous industrial materials, are predominately regulated by state and local governments. Many states have beneficial use programsExit and should be consulted to determine whether beneficial uses of spent foundry sands are allowed within a specific state.

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Risk Assessment of Beneficial Uses for Spent Foundry Sands in Soil-Related Applications

EPA launched a collaborative effort to evaluate the potential risks of using silica-based spent foundry sands produced by iron, steel and aluminum foundries, and to encourage beneficial use. Based on the results of the risk assessment, EPA supports the beneficial use of these materials, because the constituent concentrations found in silica-based spent foundry sands from iron steel and aluminum foundries are below the Agency’s health and environmental benchmarks.

Any conclusions drawn by the risk assessment should be understood within the limitations and scope of the evaluation, including the following:

  • Only silica-based spent foundry sands from iron, steel and aluminum foundries are evaluated in the risk assessment. In contrast, spent foundry sands from leaded brass and bronze foundries are often regulated as RCRA hazardous waste. Spent foundry sands from non-leaded brass foundries and spent foundry sands containing olivine sand also are not evaluated in the risk assessment.
  • In addition to spent foundry sands, foundries can generate numerous other wastes (e.g., unused and broken cores, core room sweepings, cupola slag, scrubber sludge, baghouse dust, shotblast fines). The assessment, however, applies only to spent foundry sands as defined in the assessment: molding and core sands that have been subjected to the metal casting process to such an extent that they can no longer be used to manufacture molds and cores. To the extent that other foundry wastes are mixed with spent foundry sands, the conclusions drawn by the assessment may not be applicable.

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