Tungsten (VI) speciation in hydrothermal solutions is investigated through in-situ Raman spectroscopy coupled with the fused silica glass capillary technique at temperatures up to 400 °C. The effect of temperature, pH, chlorinity and carbonate are evaluated systems highly soluble salts Na2WO4 Na6W12O39. At all temperatures, tungstate ion WO42? (927 cm?1) only W species solution pH > 10. a given...

Tungsten is one of the strategic metals produced from tungsten ores through sodium tungstate. The hydrometallurgical process a common technology for extracting tungstate high-grade concentrates. grade ore decreasing, and mineral processing to produce concentrate suitable becoming more difficult. It desirable develop new effectively recover complex low-grade ores. A fundamental study on pyrometa...

In previous work, we studied the electronic structure of several molybdate and tungstate crystals having the scheelite structure. The wolframite structure is another common form for molybdate and tungstate materials. In this paper, we compare two chemically similar materials that naturally form in the scheelite and wolframite structures—CdMoO4 and CdWO4, respectively. We compare the electronic ...

Tungsten oxide supported on ZrO2 is receiving increased attention as a solid acid catalyst due to its important industrial applications, such as the isomerization of C4-C8 alkanes to upgrade gasoline octane number. It is known that the catalytic activity depends on the structure of WOx species and their interaction with ZrO2 support [1], so a thorough structural characterization is essential fo...