Production of Reactive Metals by Molten Salt Processing

Molten Salt electrolytic processes offer unique opportunities to extract and refine reactive metals where gaseous or metallothermic reduction, hydrometallurgical extraction and aqueous electrolytic methods are thermodynamically constrained. Production of aluminum and magnesium by molten salt electrolysis are well known commercial processes. Several other reactive metals, such as lanthanides and actinides, as well as beryllium and calcium, make use of molten salt processing for extraction and refining. This paper describes the science of molten salt electrochemistry for electrowinning and electrorefining. In addition, recovery of metals from waste process salts by molten salt reduction as well as oxidation has been discussed. Material issues in design of molten salt reactors have been included. Case studies presented in this paper include (i) recovery of calcium metal from molten salt waste forms and (ii) separation of cerium oxide by oxygen sparging of molten salts. Experimental data have been included to justify the suitability as well as limitations of these specific processes.