Technology needs assessment: Evaluation of the molten salt oxidation process technology

Molten salt oxidation (MSO) is a potential treatment technology for numerous US DOE waste forms. This report is a baseline evaluation of MSO technology (as developed by Energy Technology Engineering Center and Rockwell International) to establish its present and potential readiness to treat DOE wastes, particularly mixed wastes. Much of the information in this report was derived from a peer review meeting in Woodland Hills, California, on November 12--14, 1991. The panel members and other participants provided expertise in treatment technologies, DOE's waste problems, safety and systems analyses, and regulatory and public issues and concerns. The basic concept of MSO is to introduce wastes and air into a bed of molten salt, oxidize organic wastes in the molten salt, use the heat of oxidation to keep the salt molten, retain metals and radionuclides within the salt melt, and remove the salt for disposal or for processing and recycling. Sodium carbonate, or sodium carbonate mixed with other salts (e.g., potassium carbonate or NaCl) is typical of the salts used as the melt. The most common operating temperatures are 900 to 1000 C, and the feed stocks may be gases, solids, organic liquids, aqueous solutions, or slurries. The molten salt acts as catalyst for the oxidation reactions; enhances organic compound destruction; helps retain ash and soot; and helps capture/react with heavy metals, radionuclides, and acid gases. MSO, used as a primary or secondary treatment system, acts as an acid gas scrubber and requires a particulate treatment system to clean the off gas. As part of evaluation process, the Peer Review Panel examined MSO as a treatment technology for specific waste groups. The Peer Review Panel concluded that the MSO process could potentially treat a variety of DOE wastes, particularly the mixed and hazardous wastes. Advantages and disadvantages of MSO over incineration are identified. The formation of an MSO task force is recommended