| abstract |
A process for recovering tungsten values in the form of ammonium paratungstate from tungsten ores and ore concentrates, particularly wolframite ores and ore concentrates, incorporating a plurality of steps for necessary removal of impurities and formation of the product ammonium paratungstate. The steps of the process include grinding, caustic leaching, filtrations, chemical treatment including acidification particularly for the removal of silica impurities, further filtration, solvent extraction of the tungsten values, stripping of the tungsten values from the solvent solution in the form of ammonium paratungstate, and recovery of the ammonium paratungstate product. The caustic leaching step may be carried out in the substantial absence of oxygen. |