Hydrothermal Extraction of W042- Ion from Scheelite

Abstract

A new wet metallurgy of CaWO, from middle to low quality scheelite ores was proposed. The alkaline hydrothermal extraction of WO₄^2- ion from the scheelite was investigated by using a microautoclave. Using an alkaline solution containing NaOH, Na₂CO₃ and Ca (OH)₂ high extraction ratios of WO₄^2- ions, above 90%, and low extraction ratios of SiO₃^2- ions, below 10%, were attained at 250°C for 5 min. The Si₃^2- ions mostly reacted with Ca (OH)₂to form insoluble orthosilicate (tobermorite).