Production of pure tungsten oxide from scheelite concentrates

Sebahattin Gürmen*, Servet Timur, Cüneyt Arslan, Ismail Duman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

Scheelite concentrates, obtained from Uludag, Bursa (Turkey), containing roughly 50% W, are treated by the chelate-added acidic leaching route. Dissolved tungsten runs are then selectively precipitated by the addition of 'ammonia ion-containing' reagents - either organic or inorganic - and thus are purified from other ions present in the solution. Selective precipitation of pure (>99%) tungstate salt was realized from the polytungstate solution at 25°C by adding a 'chelate-breaking agent' at a NH4+/WO3 weight ratio of ≥ 1/4. The formula of the complex salt is indicated by (NH4)3PW12O40·9H2O . The optimum precipitation conditions are investigated with the aim of making pure tungsten oxide via a thermal breakdown process. Tri-ammonium-dodeka-tungstate-phosphate salt can be easily converted to nanometer-sized WO3 particles by a simple calcination operation carried out above 650°C. Weight loss ratios of the samples vary between 8.7 and 9.6% at the end of this 2-h thermal breakdown process. Tungsten trioxide obtained can be suitably employed in tungsten-related powder metallurgy applications with its extremely low impurity content of 0.04% Mo, 0.15% SiO2, 0.06% Fe and 0.03% Al.

Original languageEnglish
Pages (from-to)221-228
Number of pages8
JournalScandinavian Journal of Metallurgy
Volume31
Issue number3
DOIs
Publication statusPublished - Jun 2002

Keywords

  • Acidic leaching
  • Chelate-added acidic leaching
  • Hydrometallurgy
  • Scheelite concentrate
  • Tungsten

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