Analysis of tungsten in low grade ores and geological samples

Abstract

Abslract. The determination of tungsten in low grade ores and geological samples is one of the most difficult and challenging tasks. Many of the associated elements, especially molybdenum interfere. These have to be overcome by suitable methods of separation or suppression of the interfering elements. Since the concentrations are low, instrumental methods are preferred over the classical methods. Thus spectrophotometry, fluorometry, atomic absorption spectrometry, atomic emission spectrometry, X-ray fluorescence, neutron activation analysis, electro analytical methods and chromatography are preferred. These are discussed in this review.

Kinetics of Scheelite Conversion in Sulfuric Acid

“…The residue was washed, then dried at 363 K in an oven for 8 h to obtain the leaching residue sample, followed by weighing on an analytical balance. Subsequently, the WO3 contents in the residue sample and the leaching solution was measured respectively by thiocyanate method 22 to reduce the experimental error. Presuming that the H2WO4 in the converted product was completely dissolved and the unreacted scheelite was not decomposed at all, the conversion ratio of scheelite to H2WO4 in the conversion process can thus be determined using Eq.…”

Sustainable and efficient leaching of tungsten in ammoniacal ammonium carbonate solution from the sulfuric acid converted product of scheelite

“…Subsequently, the residue was weighed using an analytical balance, and its WO3 content was measured using the thiocyanate method (Crouthamel and Johnson, 1954;Srivastava et al, 1996). The leaching yield of WO3 in ammoniacal (NH4)2CO3 solution was calculated by Equation (5).…”

Wolframite Conversion in Treating a Mixed Wolframite–Scheelite Concentrate by Sulfuric Acid

“…Scanning electron microscope (Quanta 650, FEI) and energy dispersive spectrometer (Quantax 200, Bruker) were used to investigate the morphologies and element distributions of the solid converted products. Additionally, the tungsten leachability of the solid converted product was examined in an aqueous ammonium carbonate solution, followed by determining the WO3 content of the leaching residue using the thiocyanate method 20 .…”