Metal casting produces spent foundry sands. The sand purchased by foundries to make casting molds is reused numerous times.
FREMONT, CA: The industry of metal casting generates spent foundry sands. Foundries use new, virgin sand to build casting molds, which can be reused many times. This usage renders the sand unsuitable for casting molds, and a portion is continuously removed and replaced with virgin sand. Repurposing or disposing of foundry sand is the preferred method of disposal.
Beneficial Uses for Spent Foundry Sands
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The EPA's risk assessment for the beneficial uses of spent foundry sands determined that silica-based spent foundry sands produced by iron, steel, and aluminum foundries can be reused safely to conserve energy, reduce the need to mine virgin materials, and lower costs for both producers and end users. EPA endorses using silica-based foundry sands from the following foundry types in the following applications
—as a component of artificial soil, as a component of soil-free media (potting soil), and as the base layer of roadways (subbase).
The EPA estimates that approximately 2.6 million tons of discarded foundry sand are used outside of foundries yearly. Iron, steel, and aluminum sands account for 96 percent of the beneficially used foundry sand. Around 14 percent of these sands are currently utilized in soil-related applications. The EPA thinks the applications reviewed in the 2014 risk assessment have the potential for substantial market expansion and increased environmental benefits.
For foundries and recyclers of foundry sand, state regulators should ensure planned uses align with state waste management programs and beneficial use programs, compliance with environmental limits, engineering performance criteria, and other state requirements
relating to the sand's chemical and physical properties.
Regulations for Beneficial Reuse of Foundry Sands
The Resource Conservation and Recovery Act encourages ecologically responsible materials management techniques to maximize the use of recoverable resources and promote resource recovery. Using regulatory and non-regulatory techniques, the EPA seeks to incentivize behavioral changes to improve materials management. The primary purpose of the EPA in the management of nonhazardous solid waste, including the evaluation of beneficial applications, is to provide national leadership and technical assistance. State and municipal governments are primarily responsible for regulating nonhazardous solid wastes, including nonhazardous industrial products, under RCRA. Numerous states have beneficial use programs, which should be examined to discover if practical uses of spent foundry sands are permitted in a particular state.
Risk Evaluation of Soil-Related Applications for Beneficial Uses of Spent Foundry Sands
The EPA initiated a collaborative initiative to analyze the potential dangers of employing silica-based waste foundry sands from iron, steel, and aluminum foundries and to promote their beneficial reuse. Based on the risk assessment results, the EPA approves the beneficial use of these materials because the amounts of constituents in silica-based spent foundry sands from iron steel and aluminum foundries are below the Agency's health and environmental criteria.
Any findings obtained from the risk assessment must be understood in the context of its limitations and scope, which include the following:
Only discarded foundry sands containing silica from iron, steel, and aluminum foundries are considered in the risk evaluation. In contrast, discarded foundry sands from foundries producing leaded brass and bronze are frequently controlled as RCRA hazardous waste. The risk evaluation examined neither wasted foundry sands from non-leaded brass foundries nor spent foundry sands containing olivine sand.
Foundries can produce various waste products, not just used sand (e.g., unused and broken cores, core room sweepings, cupola slag, scrubber sludge, baghouse dust, and shot blast fines). The evaluation applies, however, only to spent foundry sands as defined by the assessment: molding and core sands that have been exposed to the metal casting process to the point where they can no longer be used to create molds and cores. If additional foundry wastes are mixed with wasted foundry sands, the assessment's conclusions may not apply.
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