Overview of used antifreeze and industrial glycol recycling by vacuum distillation

A leading method of reclaiming ethylene glycol from both used automotive coolants and waste industrial glycol streams is vacuum distillation. Over 15 million gallons per year of total glycols are recovered by this technology, which are marketed for use in antifreeze and industrial chemicals. It is a robust technology, tolerant of many common feed contaminants, and producing minimum waste. This paper presents an overview of vacuum distillation as one part of a multistep process for recovering glycols from a wide variety of feedstreams. Described are industry practices for laboratory prescreening of feedstreams, process adjustments and pretreatments, distillation technologies and post-distillation polishing methods. In each section, information and data are presented from two independent facilities and for several streams processed at each facility. It is concluded that the facilities participating in this study can reliably produce ethylene glycol suitable for the production of ASTM specification engine coolants.