Development of sustainable, low-emission “sand-binder” molding systems for casting processes

Environmental issues are more pressing in molding processes that use organic binders, where, in addition to emissions of fines and respirable crystalline silica (RCS) derived from silica sands, a variety of volatile organic compounds (benzene-toluene-xylene (BTX), formaldehyde, furfuryl alcohol (FA), phenol, etc.) are generated. Added to these are the combustion gas emissions generated during casting and solidification of parts (Co, CO2, NOx, etc.).

This technical article presents the development of alternative “sand-binder” systems aimed at improving environmental conditions in foundries:

• Development of a molding material derived from the recovery of black steel slag waste, a material free of free silica and therefore of interest from the perspective of eliminating respirable crystalline silica emissions.
• On the other hand, the development of an inorganic binder (geopolymer) based on alkaline activation technology (AAT) in which properly treated and selected black steel slag is also used as a solid precursor. In this case, the environmental benefit sought is the reduction of volatile organic compound (VOC) emissions.

Both developments share the common denominator of seeking new ways to recover black steel slag, the main waste generated by the steel industry, a sector classified as one of the most significant in terms of environmental impacts due to its high consumption of materials, non-renewable energy, and waste generation.