Ammonium Paratungstate as Raw Material for Preparing Ammonium Metatungstate 2/2

Ion exchange method, specific steps are carried out as follows:
1. Heating ammonium paratungstate(APT) to 130~140℃, and keep the temperature for 1~8 hours;
2. Transfer the formation of step 1 into slurry, and boiled to 80~100℃ for 2~6 hours to form ammonium metatungstate (AMT) solution;
3. Concentrate and crystallization, filtrate to separation, and then dry to get AMT crystal.

Electrodialysis method, the implementation steps are as follows:
1. Add APT into the anode chamber, and electrify;
2. When the electricity passes by, the ammonium ions go into the cathode chamber through the anion exchange membrane, and the concentration of AMT ion in the anode chamber increases;
3. Release the AMT solution from the cathode chamber;
4. Concentrate and crystallization, filtrate to separation, and then dry to get AMT crystal.

Shallow thermal decomposition - resin exchange method, the steps are as follows:
1. Place the APT in the enamel plate, and put them in a constant temperature oven at 240℃ heated for 25~30 minutes;
2. Remove the reactants, slowly pour into pure water of 95℃ with stirring;
3. Add L type resin when the majority of solid is dissolved, control pH value between 3~4, and stir for 30min in an environment of constant temperature;
4. Filter he mixture through a stainless steel screen to remove resin and debris;
5. Lay aside the filtrate for 12 hours, then vacuum filtration to remove insoluble impurities and tungsten compounds;
6. Heat and condense to crystallization, and drying by 50-60℃ air for 2 hours to obtain AMT crystal.

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