|Dungan, Robert - Rob|
Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2009
Publication Date: 3/29/2010
Citation: Dayton, E.A., Whitacre, S.D., Dungan, R.S., Basta, N.T. 2010. Characterization of Physical and Chemical Properties of Spent Foundry Sands Pertinent to Beneficial Use in Manufactured Soils. Plant and Soil Journal. 329:27-33.
Interpretive Summary: Foundries use millions of tons of sand each year to create metalcasting molds and cores, much of which is disposed of in landfills after it fails to meet engineering specifications. The spent foundry sands (SFSs), which are non-hazardous in nature, can be used as aggregate in manufactured soils (e.g. topsoils, potting soils) and geotechnical applications. However, many end users and states are reluctant to use these materials and they have not been thoroughly characterized from a physical and chemical standpoint. The objective of this work was to measure: (i) chemical and physical properties important to soil quality and function and (ii) total and soluble elemental content (of 39 SFSs) in order to evaluate SFS suitability as a component in manufactured soils. Metals, which can present a potential risk to plants and grazing livestock when at elevated concentrations, were determined in the SFSs. In general, they were lower than found in natural background soil suggesting there is little or no contamination of the virgin sand due to the metal casting process. In order to determine any potential toxicity to plants, a germination study was conducted with lettuce that was grown in soils containing up to 50% SFS by weight. The study showed little effect on germination, as the median germination rate was 97% relative to the controls. The SFSs tested in this study possess soil-like qualities, and blending with other residual materials or byproducts will allow the creation of a manufactured soil with specific physical and chemical properties to meet growing needs.
Technical Abstract: Of 2,000 United States foundries, 93% produce ferrous or aluminum castings, generating 9.4 million tons of non-hazardous spent foundry sand (SFS) annually, of which only 28% is beneficially used. The U.S. EPA Resource Conservation Challenge identifies SFS as a priority material for beneficial use and soil blending as a potential reuse option. The objective of this work was to measure: (i) chemical and physical properties important to soil quality and function and (ii) total and soluble elemental content, of 39 SFSs, in order to evaluate SFS suitability as a component in manufactured soils. Total elemental content is generally lower than natural background soil suggesting there is little or no contamination of the virgin sand due to metal casting. Pore water elemental concentrations were low, generally, below detection. However, both total and soluble elemental content show a contribution of plant nutrients. A lettuce (Lactuca sativa) germination study showed a median germination of 97% relative to the control. The 39 SFS have soil-like qualities due to additions of clay, and organic material to virgin sand to make casting molds. Blending SFS at varying ratios with other materials allows “tailoring” of a manufactured soil’s chemical and physical properties to meet specific growing needs.