METHOD OF PRODUCTION OF CALCIUM TUNGSTATE Russian patent published in 2007 - IPC C01G41/00 C01F11/00 C22B3/04 

FIELD: hydrometallurgy of rare-earth metals at processing walframite concentrates.

SUBSTANCE: calcium tungstate produced according to this method may be used for treatment of steel instead of ferro-tungsten or for production of tungstic acid. Proposed method includes treatment of potassium tungstate with calcium nitrate solution at molar ratio of potassium tungstate to calcium nitrate within 1.0-1.1. Proposed method is waste-free method since solution of potassium and calcium nitrates may be used as complex mineral fertilizer. Extraction of tungsten from solution is increased to 98.4%.

EFFECT: enhanced efficiency; high purity of calcium tungstate.

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