The ester-cured phenolic coldbox binder system consists of a water-based alkaline phenolic resole resin that is cured by gassing with methyl formate vapors. Because methyl formate is a coreactant, a sufficient level of vapor must come in contactwith the resin binder to complete the chemical reaction and harden the resin/sand mixture. In fact, a significant excess of methyl formate is required to accomplish complete curing of the resin in all areas of a core or mold, even when minimized with theapplication of proper gassing techniques.The excess vapors are routinely air purged from the hardened sand, and exhausted. Typically, the exhaust vapors are merely vented to the atmosphere. This results in not only a significant economic loss of methyl formate, but also Volatile Organic Compound (VOC) emissions added into the atmosphere. Thus, there are both economical and environmental reasons for recovery of the excess methyl formate used with this binder system.This paper describes a process for recovery of VOCs, based on gas separation membrane technology. The process is applied to the foundry industry for the recovery of methyl formate. Recovery efficiency and the results from actual foundry pilot tests arepresented. Comparisons to other VOC control techniques are briefly described. Applicability of the process to the recovery of amines from the phenolic urethane coldbox process is also discussed.
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