Regeneration of used sand with sodium silicate binder by wet method and their core manufacturing

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.