Location: Northwest Irrigation and Soils Research
Title: Mid-infrared spectroscopic analysis of chemically bound metalcasting sands Authors
|Miguel, Roberto -|
|Reeves Iii, James|
Submitted to: Journal of Analytical & Applied Pyrolysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 6, 2014
Publication Date: N/A
Interpretive Summary: Foundries around the world use sand as part of the metalcasting process, much of which are discarded when they no longer meet technical specifications. The waste foundry sands (WFSs) can be beneficially used in various agricultural and geotechnical applications, but in many cases this is not permitted due to concerns over potential organic contamination. In this study we examined ferrous and non-ferrous WFSs using mid-infrared (MIR) spectrometry to evaluate changes to organic binders during the high-temperature casting process. Based upon MIR spectra, our results indicate that binders closer to the molten metal interface or exposed to higher temperatures undergo more complete thermal degradation. Mid-infrared spectrometry could potentially be used as a technology to identify WFSs with low residual binder levels that are suitable for beneficial use applications.
Technical Abstract: Foundries around the world discard millions of tonnes of molding and core sand each year even though they can be beneficially used in manufactured soils and geotechnical applications. Despite their usefulness as an aggregate replacement, some environmental authorities are concerned over potential negative impacts associated with residual organic binders in waste foundry sands (WFSs). In this study, chemically bound molding and core sands were obtained from aluminum, bronze and iron foundries that used alkyd urethane, phenolic urethane, Novolac, and natural organic binders. The aim was to use mid-infrared (MIR) spectrometry to assess changes within the molding and core sands during the casting process, with a specific focus on proximity to the casting interface and casting temperature. In addition, the MIR spectra were compared to total carbon concentrations in the sands. Bands associated with C-H stretching were detected in most WFSs. The MIR spectra and total carbon data demonstrated that casting temperature and proximity of the sand to the molten metal contributed to various levels of thermal degradation of the organic binders. Our results also provided preliminary evidence that MIR spectroscopy could be used to identify WFSs with less residual binder.