How to prepare high purity ammonium metatungstate crystal? The researchers proposed a method for preparing high-purity AMT crystals - neutralization-nanofiltration coupling process. This method can not only obtain a high concentration AMT solution to reduce the cost for the subsequent crystallization process, but prepare AMT with less impurity content to ensure the preparation of high purity ammonium metatungstate.
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A Preparation Method of High Purity Ammonium Metatungstate Crystal
Add dilute nitric acid to ammonium paratungstate (APT) solution. Under appropriate acidity, temperature and other reaction conditions, APT is gradually converted into AMT. Wherein, the temperature in the process of dissolution and transformation should be controlled at 80 -95 °C. The AMT solution is passed through a nanofiltration membrane device, and after concentration and washing processes, a pure AMT solution is obtained. At certain time intervals, samples are taken to analyze the concentration of tungsten and nitrate ions in the feed liquid and permeate; the pressure of the permeate is directly read by the pressure gauge.
