Preparation of Ammonium Paratungstate from a Sodium Tungstate-Sodium Chloride Phase

摘要

Previous Bureau of Mines research has shown that tungsten ores containing as little as 40 pct WO3(2-) can be processed by a high-temperature molten-salt extraction technique to produce a tungstate-bearing sodium chloride phase with 99 pct W recovery and little impurity contamination. The objective of the work was to demonstrate that the tungstate-bearing sodium chloride phase can be a suitable feed material for preparing ammonium paratungstate by a modification to the present industrial solvent extraction process. A combined crossflow-countercurrent flow solvent extraction technique to extract tungsten is presented. Implementation of the processing technique would improve tungsten recovery from concentrates and simplify processing operations.