Thermal decomposition mechanism of ammonium phosphotungstate hydrate in air atmosphere


Kalpakli A. O. , İlhan S. , Kahruman C. , Yusufoglu I.

INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS, cilt.31, ss.14-20, 2012 (SCI İndekslerine Giren Dergi)

  • Cilt numarası: 31
  • Basım Tarihi: 2012
  • Doi Numarası: 10.1016/j.ijrmhm.2011.08.007
  • Dergi Adı: INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
  • Sayfa Sayısı: ss.14-20

Özet

Production of W from scheelite mineral (CaWO4) by hydrometallurgical processes has grown up in the last decade. CaWO4 dissolves in HCl solutions containing H3PO4 as chelating agent and forms phosphotungstic acid (H-3(PW12O40), PhTA). Ammonium phoshpotungstate hydrate ((NH4)(3)[PW12O40NH2O, APhT) can be precipitated by addition of NH4Cl to solutions containing PhTA and WO3 can be produced by the thermal decomposition of APhT. W powder can be obtained by H-2 reduction of WO3.