No abstract

No abstract

As antimony is typically present in industrial and commercial products only in small amounts, the concentration of antimony in waste types is low and a limited amount of antimony is currently recycled. One product relatively rich in antimony is the metal oxide varistor (MOV) used for overvoltage protection in electric circuits. To increase the antimony concentration, the MOV was pulverized (\ 65 lm) and leached, resulting in an insoluble MOV residue containing 186 ± 2 mg/g of antimony. This work investigates the thermal decomposition and carbothermal reduction of pure metal oxides (Sb 2 O 3 , Bi 2 O 3 , and ZnO) and MOV residue. Thermogravimetric (TG) analysis was used in order to propose a temperature range in which it is possible to separate antimony oxide from the MOV residue. TG results indicate that during thermal decomposition of pure metal oxides, sublimated antimony oxide can be recovered at 650°C, leaving Bi 2 O 3 and ZnO unreacted. The addition of carbon caused mainly volatilization, with some reduction, of Sb 2 O 3 and reduction of Bi 2 O 3 to occur at nearly the same temperature, approximately 600°C. However, volatilization of Bi was not troublesome below 800°C due to slow kinetics. Thermal decomposition of antimony from the MOV residue was not possible in the temperature range studied (\ 1000°C), while carbothermal reduction to the MOV residue revealed antimony volatilization occurred near 800°C.

Practical information is provided on electrochemical measurements in molten salt systems. The emphasis is on chloride and fluoride systems, but the principles are applicable to any high-temperature molten salt or molten oxide electrolyte system. Considerations are given to topics such as the functionality of electrochemical measurement equipment, reference electrodes, materials selection and chemical compatibility, interpretation of electrochemical measurement signals, molten salt properties, and laboratory practices.

No abstract