METHOD OF EXTRACTING TUNGSTEN FROM SCHEELITE Russian patent published in 2014 - IPC C22B34/36 C22B3/06 

FIELD: chemistry.

SUBSTANCE: claimed is a method for the extraction of tungsten from scheelite. The introduction of an acid mixture, containing sulphuric acid and orthophosphoric acid, into a decomposition reactor, heating to 70-100°C and the addition of sheelite under control of a ratio of liquid and solid phases at the level of 3:1-8:1 l/kg are realised. Then, after 1-6 h of the reaction carried out are filtration and crystallisation of the obtained filtrate, which is compensated with sulphuric acid, consumed in the reaction for obtaining a crystal of phosphotungstic acid and a residual solution. After that, dissolution of the crystal of phosphotungstic acid in water is carried out with its conversion into a solution of ammonium tungstate, containing 200-300 g/k of WO₃. The said solution is used for the preparation of ammonium paratungstate. The residual solution after compensation with orthophosphoric acid and water to the initial level is directed to scheelite leaching.

EFFECT: reduction of expenditures and reduction of tungsten loss.

4 cl, 7 dwg, 1 tbl, 9 ex