New opportunities for metals extraction and waste treatment by electrochemical processing in molten salts

Abstract

Molten salt electrolysis is a proven technology for the extraction of metals—all the world's primary aluminum is produced in this manner. The unique properties of molten salts also make them excellent media in which to treat a variety of forms of waste. Of special note in this regard is electrolysis in molten oxides, a concept put forward by the author, initially as a “clean technology” for producing primary metal. However, in the context of waste treatment, elcctrolysis in molten oxides is a process offering the prospect of changing the valence of dissolved heavy metals while making pure oxygen gas as the main by-product. Laboratory tests conducted at a temperature of 1550 °C on chromate sludge dissolved in melt composed of Al2O3, SiO2, CaO, and MgO have confirmed electrochemical production of oxygen on a carbon-free anode.