A Pulse Voltage Application in Electrochemical Reduction of Solid CaWO_4 Powder

摘要

Scheelite is the most abundant mineral of tungsten, but wolframite is used more than scheelite due to easier dissolution in alkaline solutions used in present processing methods. An alternative method based on electrochemical reduction of CaWO_4 by direct current applications in molten salt solutions was recently reported. Pulse voltage and constant voltage reduction mechanisms were compared and an optimization of reduction kinetics was achieved in this study. The results have shown that faster reduction rates could be achieved during pulse voltage applications compared to constant voltage applications, when average value of pulse voltage application was the same as its constant counterpart. Furthermore, analysis of charge, energy and theoretical reduction graphs showed that reduction of calcium tungstate occurs at higher potential differences than 2.2 V, between calcium tungstate and graphite.