ARS | Publication request: Use of standardized procedures to evaluate metal leaching from waste foundry sands

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 3, 2012
Publication Date: March 1, 2013
Citation: Miguel, R.E., Ippolito, J.A., Porta, A.A., Noriega, R.B., Dungan, R.S. 2013. Use of standardized procedures to evaluate metal leaching from waste foundry sands. Journal of Environmental Quality. 42(2):615-620.

Interpretive Summary: Each year foundries around the globe generate millions of tons of molding sand that generally end up in landfills. Despite the fact that most foundry sands are treated as a waste, there are efforts to beneficially use foundry sands in a variety of agricultural and geotechnical applications. While most waste foundry sands (WFSs) are not hazardous in nature, efforts to increase their beneficial use have encountered resistance due to concerns over potential metal contamination. To assess the toxicity of many byproducts, including WFSs, standardized leaching procedures are often utilized. In this study we subjected ferrous and non-ferrous foundry sands to three commonly used procedures to determine the mobility of metals. Our results demonstrated that concentrations of arsenic, barium, cadmium, chromium, copper, nickel and lead in leaching extracts from the WFSs were similar to those from virgin sands. In addition, the concentrations were below levels considered hazardous. Thus, beneficially used WFSs should present little or no risk to human health and the environment.

Technical Abstract: As part of the casting process, foundries create sand molds and cores to produce ferrous and non-ferrous metal castings. After the process, a portion of the sand is discarded and becomes waste foundry sand (WFS). The aim of this study was to quantify metals (i.e. Ag, Ba, Cd, Cr, Cu, Ni, Pb, and Zn) in leaching extracts from a variety of waste molding and core sands from ferrous and non-ferrous foundries using the Extraction Procedure, Toxicity Characteristic Leaching Procedure, and ASTM water extraction procedure. The WFS metal extract concentrations were compared to those found in virgin silica sands and Argentinean and U.S. hazardous waste laws to determine if the WFSs met toxicity limits. The majority of the WFS extracts analyzed, regardless of metal cast and binder type, contained metal concentrations similar to those found in virgin sand extracts and were below levels considered hazardous. Consequently, it appears most WFSs can be beneficially used as a substitute for virgin aggregate in geotechnical and agricultural applications without causing risk to human health and the environment.