Regeneration of used sand with sodium silicate binder by wet method and their core manufacturing
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ORIGINAL ARTICLE
Regeneration of used sand with sodium silicate binder by wet method and their core manufacturing Kyeong Ho Kim1,2 · Min A. Bae1 · Man Sig Lee1,3 · Hung‑Suck Park2 · Jae Ho Baek1 Received: 25 February 2020 / Accepted: 28 August 2020 © Springer Japan KK, part of Springer Nature 2020
Abstract Organic binders that are used in sand casting emit high amounts of hazardous pollutants and volatile organic compounds during the casting process. Inorganic binders do not emit harmful gases and are widely used in aluminum casting processes. However, there is a paucity of studies on the reuse of waste sand using inorganic binders in casting processes. In the study, waste sands using an inorganic binder and a powder were recycled via wet regeneration and the effects of residual powder on regenerated sand were analyzed. The wet regeneration of molding and casting sands was performed by cleaning, followed by grinding in a 0.2-M KOH solution and then removing the residual binder using water. The molding sand was regenerated to the same level as the raw sand via the 0.2-M KOH solution followed by water cleaning twice. The casting sand removed most of the binder via additional water cleaning for the regeneration condition of the molding sand. Although the powder was completely removed from the regenerated molding sand, the regenerated casting sand remained used powder; the residual powder had a 78% performance. Thus, the regenerated casting sand was reusable only when adding binder without powder. Keywords Waste sand · Inorganic binder · Powder · Regeneration · Regenerated sand
Introduction Organic binders used in sand casting are mostly phenol and furan resins, and generally used as resin-coated sand (RCS). Organic binders are exposed to high temperatures during casting processes and emit harmful gases such as formaldehyde and volatile organic compounds [1–5], which pollute the environment for workers and the atmosphere around casting plants. An inorganic binder, based on sodium silicate, was recently developed to solve these environmental problems [6]; it is widely used in the aluminum casting process. This inorganic binder does not produce harmful * Hung‑Suck Park [email protected] * Jae Ho Baek [email protected] 1
Ulsan Division, Korea Institute of Industrial Technology (KITECH), Ulsan 44413, South Korea
2
Department of Civil and Environmental Engineering, University of Ulsan, Ulsan 44610, South Korea
3
Department of Green Process and System Engineering, University of Science and Technology (UST), Ulsan 44413, South Korea
gases during casting processes and the quality of the resulting casting products is greater than or comparable to those the organic binders [7]. Waste sand from sand casting processes using organic and inorganic binder needs to be regenerated. Its regeneration methods include dry (mechanical), wet, and thermal techniques. Joseph et al. [8] used an alkaline urethane (organic) binder and investigated the reusability and quality of the regenerated sand after mechanical regenera
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