Grade 1 yellow tungsten oxide, also known as grade 1 tungsten trioxide, with grade of WO3-1. Whether it is grade 1 or grade 2 yellow tungsten oxide powder, even super grade yellow tungsten oxide powder, they are all from the tungsten ore. But, how to measure the content of tungsten trioxide in tungsten ore?
Thiocyanate photometric method is one of various methods to measure the content of WO3 in tungsten mine. Its strengthening processes show as bellows:
Step one: Dissolve a small amount of sample, in the presence of ammonium fluoride, with HCL, HNO3 and HClO4. The tungsten is precipitated in the form of tungstic acid and part of molybdenum is precipitated in the form of molybdic acid.
Step two: Filtered to separate tungsten and molybdenum with the most coexistence elements, and then dissolved tungstate and molybdic acid with ammonia. The filtrate is evaporated to dryness, burning, and removing silicon by HF. Weighing the total weight of WO3 and MoO3 after burning.
Step three: Add sodium hydroxide to dissolve WO3 and MoO3, and then measure the weight of MoO3 by thiocyanate photometric method.
Step four: Measure mass fraction of tungsten trioxide in residue and filtrate by thiocyanate photometric method to correct the result.
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