The Molten Carbonate Process is based on the use of molten carbonate salts to remove sulfur dioxide and last traces of fly ash from flue gases. The salt stream is regenerated and recycled. It follows that fly ash must be continually removed from the molten salts, or it will accumulate and finally render the liquid salt to a paste. This report describes investigations of the physical properties of fly ash and methods for filtering the ash from suspension in molten salts. (Author)