From the EPA.gov website:
Spent Foundry Sand
Basic Information
Spent foundry sands are generated by the metal casting industry.
Foundries purchase new, virgin sand to make casting molds, and the sand
is reused numerous times within the foundry. However, heat and
mechanical abrasion eventually render 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
a non-foundry application or landfilled. It is estimated that less than
30 percent of the 10 million tons of spent foundry sands generated
annually are recycled. The Agency believes a greater percentage of spent
foundry sand can be safely and economically recycled.
Beneficial Use
The EPA has found 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. The 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);
As a foundation layer of roads (subbase).
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.
Risk Assessment
The EPA, in conjunction with the U.S. Department of Agriculture
(USDA) and the Ohio State University (OSU), 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. The risk assessment focused on soil-related
applications; specifically manufactured soil, soil-less potting media,
and as subbase, which is a foundation layer of roads. The overall goals
for the risk assessment were to:
Review the available information on spent foundry sand in
soil-related applications
Identify likely exposure pathways and receptors associated with various
uses
Use a combination of screening and modeling methods to determine whether
the proposed uses of spent foundry sand are protective of human health
and the environment and
Discuss the findings within the context of certain overarching concepts
(e.g., the complexities of soil chemistry) and provide conclusions.
Based on the results of the risk assessment, the EPA and the USDA
support the beneficial use of these materials that would otherwise go to
waste, 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 (SFS) 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. SFS from non-leaded brass foundries
and SFS containing olivine sand also are not evaluated in the risk
assessment.
In addition to SFS, 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 SFS as defined in the assessment: molding and core sands
that have been subjected to the metalcasting 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 SFS, the conclusions
drawn by the assessment may not be applicable.
Environmental Benefits
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. The EPA believes that there is potential for
substantial growth in the beneficial use market for the applications
studied in the risk assessment, resulting in increased environmental
benefits. The EPA estimates the environmental benefits from using
silica-based spent foundry sand in the specific applications studied in
the risk assessment, at the current use rate, results in the following
savings in one year:
The energy savings equivalent to the annual electricity consumption
of 800 homes;
CO2 emissions reductions equivalent to removing 840 cars from the road
for one year; and,
Water savings of 7.8 million gallons.
The risk assessment supports the EPA's ongoing efforts to advance
Sustainable Materials Management by demonstrating that the beneficial
use of spent foundry sand in the soil-related applications evaluated are
protective of human health and the environment and yield environmental
benefits.
Risk Assessment Documents
Please go to the following EPA.GOV page for the supporting
documentation:
https://www.epa.gov/smm/frequent-questions-about-epas-risk-assessment-spent-foundry-sands-soil-related-applications
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