APT changes water-insoluble to soluble AMT by controlling temperature, water volume, pH value, and catalytic buffer. The reaction mechanism is: 5(NH4)2O•12WO3•XH2O⇆3(NH4)2O•12WO3•YH2O+4NH4OH+2H2O removes 4 moles of ammonia and 2 moles of H2O from APT, and the reaction proceeds in the direction of AMT.
The trial production of AMT is based on WO312-30%, prepare APT slurry with ion water, add 1/100 organic acid as catalyst, and slowly neutralize with 1/20-30 dilute nitric acid for heating. After APT is fully dissolved, age for more than 2 hours, then concentrate to contain AMT50%, filter out insoluble matter, and the conversion rate is above 98%. In order to eliminate the impact of nitrate ions on the quality of AMT, AMT was mixed and precipitated with absolute ethanol solution, the mother liquor was distilled to recover ethanol, and the ethanol after pre-dehydration could be returned for reuse.
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