What Is the Reaction Equation of Sodium Tungstate?

Sodium tungstate is obtained by digestion of tungsten ores, the economically important representatives of which are tungstates, in base. Illustrative is the extraction of sodium tungstate from wolframite:

Fe/MnWO₄ + 2 NaOH + 2 H₂O → Na₂WO₄·2H₂O + Fe/Mn(OH)₂