Selection of An Alternative Asphalt Extraction Solvent

Status:  Complete
Report Date:  10/29/2003


The asphalt extraction solvent n-Propyl Bromide (nPB) was selected as an alternative solvent to the currently used d-Limonene and Trichloroethylene (TCE), based on a literature search, communication with asphalt technology experts, and a laboratory investigation. With proper handling techniques and training, nPB can be substituted for d-Limonene and TCE. Extractions with nPB use less solvent per extraction, take less time, and have a shorter drying times. Exposure levels to nPB for the labs were far below the EPA recommended value. The use of nPB for asphalt extraction and the implementation of nPB on-site recycling would generate only non-hazardous still bottom waste. The use of nPB would decrease the hazardous waste of Mn/DOT laboratories and reduce annual solvent costs. Payback time for the purchase of solvent recovery units ranges from 3 months to 20 years, depending on the quantities of extraction waste generated per year. It is recommended that all Mn/DOT district laboratories change from d-Limonene or TCE extraction solvents to nPB and conduct on-site recycling with the purchase of solvent recovery systems, and that training be given to lab personnel on the proper handling techniques for nPB.

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