Hi,
What is the best way to dissolve pure CaWO4?
I tried:
- conc. Aqua Regia
- conc. Aqua Regia + conc. HF
- conc. HNO3 + conc. HF
- 7N HNO3
- 7N HNO3 + conc HF.
Every experiment was for 55 minutes in the microwave @200 °C. At the experiments with HF I added H3BO3 afterwards and placed it for another 25 Minutes @180 °C in the microwave.
In every test H2WO4 precipitates (yellow residue), except conc. HNO3 + conc. HF, where I got first a clear solution, but over the weekend the PP-Tube turned yellow at the bottom (no residue!).
Low amount of CaWO4 (
I suggest that you check a few papers on scheelite leaching (e.g.):
Article Direct Pressure Alkaline Leaching of Scheelite Ores and Concentrates
Article Kinetics of sodium hydroxide leaching of scheelite
Article Leaching of scheelite by hydrochloric acid in the presence o...
Article Leaching Systems of Wolframite and Scheelite: A Thermodynamic Approach
Also this link may help:
https://www.911metallurgist.com/blog/cassiterite-leaching-oxide
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