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, electrolysis 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 an melt composed of Al2O3, SiO2, CaO, and MgO have confirmed electrochemical production of oxygen on a carbon-free anode.