Method for producing sodium tungstate, method for collecting tungsten, apparatus for producing sodium tungstate, and method for producing sodium tungstate aqueous solution

An apparatus for producing sodium tungstate, comprising:

• a holding container for holding a tungsten containing material;
• a supply port for supplying sodium nitrate or sodium nitrite;
• an inlet port through which outside air flows into;
• an outlet port through which gas generated by a reaction is discharged;
• a reaction container capable of holding a melt containing a reaction product produced by supplying sodium nitrate or sodium nitrite onto a surface of the tungsten containing material;
• and
• a discharge port through which said melt can be discharged to outside of said reaction container,
• said holding container being rotatably disposed within said reaction container,
• said supply port being disposed above said reaction container, and
• said discharge port being disposed below said reaction container.