Foundry Sands Recycling
EPA's solid waste management hierarchy promotes waste reduction first, recycling and reuse second, and environmentally safe disposal of any remaining material last.
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, that is, the sand that is removed, is either recycled in a non-foundry application or landfilled. Estimates are that less than 15 percent of the 6-10 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.
The recycling of nonhazardous, spent foundry sand can save energy, reduce the need to mine virgin materials, and may reduce costs for both producers and end users. For example, in cold weather climates, use of spent foundry sands as construction site base material extends the construction season because such sands wont freeze as readily as most soils.
EPA has found that spent foundry sands produced by iron, steel, and aluminum foundries are rarely hazardous. EPA supports the use of spent foundry sands from these foundry types in the following applications:2
- As partial replacement for fine aggregate in asphalt mixtures;
- As partial replacement for fine aggregate in Portland cement concrete;
- As source material for the manufacture of Portland cement; and
- As a sand used in masonry mortar mixes.
In addition, use of foundry sand from iron, steel and aluminum foundries in flowable fill, road embankments, road base, manufactured soil, agricultural amendments, and similar uses may be appropriate depending on the site and the sand composition.3 For these applications, characterization of the sand and a site-specific assessment are recommended before use.
Regardless of the application, 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.
Once a foundry decides to recycle spent sand, it is recommended that the sand be managed in a way that will prevent contamination and provide a quality product to the end user so that it is more likely that foundries will be successful in finding reuse and recycling markets for the spent sand.
Foundries that are interested in using their spent foundry sand can consult the American Foundry Society guide, Turning Used Foundry Sand into a Marketable Resource: Best Management Practices for Beneficial Reuse (PDF) (8 pp, 716K, about PDF) . This guide explains how to start a recycling program, lists sand end users general requirements, and provides a recycling program checklist. Another source of information on foundry sand recycling is the website AFS First .
In addition to promoting the recycling of spent sand, EPA encourages foundries to explore other opportunities for pollution prevention through the use of innovative and alternative technologies and materials, as well as source reduction.
1 Foundry sands also come from other types of foundries, such as from brass and bronze foundries, that are often characteristically hazardous and are therefore not included in this statement.
2 The Federal Highway Administration booklet Foundry Sand Facts for Civil Engineers (PDF) (80 pp, 265K, about PDF) (Report Number FHWA-IF-04-004) notes that spent foundry sands perform as well or better than quarried sand and natural soils in the listed applications.
3 The United States Department of Agriculture (USDA) has been conducting research on various agricultural uses of foundry sand. USDA and EPA are partners in increasing the recycling and use of industrial by-products, and USDA will be publishing guidelines for the use of industrial by-products in agricultural applications.
What is Metal Casting?
Metal casting is a process in which molten metal is poured into a mold to produce products for the automotive, valve, pipes and fittings, construction, art, agriculture, and mining industries. A wide variety of casting processes and metals (most commonly, iron, aluminum, steel, and copper-base alloys) are used.
The most common metal casting processes are green sand casting (using a sand mold), investment casting (using a ceramic mold) and diecasting (using a metal mold). The reason one process is chosen over another for the production of a cast metal part is based on factors such as the number of parts required, the complexity of the part design, the type of metal being cast, and cosmetic requirements.
For a detailed description from the private sector, please visit the Southwest Steel Casting Company .
Four challenges to the goal of increasing foundry sand recycling were identified at the December 1, 2005 National Foundry Sand Stakeholder meeting in Philadelphia (PDF) (9 pp, 81K, about PDF), which brought together EPA, state officials, the foundry industry, foundry sand end users, and the research community.
As seen in the 6-10 million ton range referenced above, we do not have solid data on the amount of foundry sand produced and recycled. To rectify this situation, our trade association partner the American Foundry Society is surveying their members. Once we establish baseline data with AFS, we will work with them to develop recycling goals.
2. Addressing Environmental Issues
A challenge to increasing foundry sand recycling is the perception that the sands are environmentally dangerous. To address this we and our research partners are continuing to examine the environmental impacts of foundry sand recycling.
- EPA is evaluating a database of more than 500 environmental tests collected from 120 foundries.
- EPAs risk models are being evaluated for their applicability to common foundry sand recycling applications.
- USDA is undertaking a multi-year evaluation of the environmental and ecological effects of foundry sands in soil. In 2007, USDA-ARS will issue guidelines for the appropriate use of foundry sand in soils.
3. Addressing State Issues
There are different levels of state comfort with the recycling of foundry sands. We will provide states with the information and tools they need to increase their knowledge base.
- EPA is developing a toolkit to assist state regulators interested in developing foundry sand recycling programs.
- Through a partnership with the Northeast Waste Management Officials Association , a database of regulatory decisions on foundry sands and other industrial byproducts is being compiled. The database will allow states to understand the decisions of their colleagues as well as share best state practices.
- An on-line foundry sand technical library is being developed and hosted by our trade association partner, AFS FIRST .
4. Supporting Market Development
While this is largely a private sector activity, EPA plans to assist in growing existing markets for foundry sand and opening new markets (such as using foundry sands to manufacture soil and applying foundry sand on farmland to capture pesticide runoff).
- The Construction Initiative highlights the use of foundry sands in building and transportation projects.
- AFS has electronically mapped foundry locations across the country. This makes it easier for potential foundry sand end users to find suppliers.
- AFS is developing Best Management Practices for foundries to ensure that foundry sand destined for recycling is high quality.
- Sector Programs: Beneficial Reuse of Foundry Sand Contains a guide of current state regulations for allowing reuse of foundry sand.
- Foundry Sand Facts for Engineers (PDF) (80 pp, 265K, about PDF) Federal Highway Administrations report providing technical information about the potential civil engineering applications of foundry sand
- Foundry Sand Chapter in the Federal Highway Administrations User Guidelines for Waste and Byproduct Materials in Pavement Construction