Reducing VOCs, Solvent Condensation for Cold-Box Coremaking

Q:  We operate a biodiesel, high-production cold-box coremaking system, but we aim to reduce VOC emissions, and reduce the threat of solvent condensation in air ducts, vents, and in baghouses — to reduce the threat of fires in ductwork. Do you have any suggestions?

A:  The biodiesel systems have been very popular to reduce volatile organic compounds (VOCs), as well as unpleasant odors in the coremaking process emissions, but there are some drawbacks. A biodiesel system works well in coremaking, but in the casting process that follows for some foundries there is frequently the potential for these biodiesel materials to condense in green sand molds. In addition, there can be more build-up that increases the %LOI (loss on ignition) in cores and return cores to the green sand molding system.

Recently we have studied VOC exempt solvents and naphthalene-depleted aromatic solvents to reduce VOCs even further, and to reduce the threat of build-up in green sand systems and build-up of combustible solvents in pouring, cooling, and shakeout. It is important to look at the entire coremaking and casting process not only to control emissions as regulated but also to reduce the threat of fires in the pouring and cooling areas, which of course would interrupt production and destroy equipment (see Figure 1.)