Ammonium Paratungstate

Introduction

Name: Ammonium Paratungstate
Abbreviation: APT
Formula: H₈N₂O₄W
Molecular weight：283.9145
EINECS: 234-364-9
CAS: 11120-25-5;14311-52-5
Formula is differing under different crystallization conditions, as follows:(1)3(NH₄)₂O-7WO₃-6H₂O ；(2)5(NH₄)₂-12WO₃-5H₂O； (3)5(NH₄)₂O-12WO₃-5H₂O ；(4) 5(NH₄)₂O-12WO₃-11H₂O

Property

Appearance: white crystal, two shapes o f flake or needle.
Solubility: slightly soluble in water (the solubility in water under 20℃ is less than 2%), insoluble in alcohol.
Thermal decomposition: APT will loses crystal water and part of the ammonia and convert to ammonium metatungstate (the AMT) when heated to 220-280℃; it will lose all crystal water and ammonia and completely convert to yellow tungsten trioxide when heated to above 600℃, the complete conversion of.

Application

1. Mainly used in the manufacture of tungsten trioxide or blue tungsten oxide, thereby preparing tungsten powder;
2. Manufacturing the upstream products of ammonium paratungstate, such as tungsten concentrate, ammonium chloride;
3. Used as laboratory reagents for preparing high-purity tungstic acid, tungsten powder or tungsten carbide powder;
4. As the colorants used in the ceramics industry;
5.The catalyst;
6. The water-absorbing gel.

Production Processes

1.Tungsten concentrate high-pressure alkali cooking (caustic soda) - ion exchange - evaporation crystallization;
2. Tungsten concentrates high-pressure alkali cooking (caustic soda) - solvent extraction - evaporation and crystallization method;
3.Pressure cooking tungsten scheelite by soviet - ion exchange - evaporation crystallization;
4.Pressure cooking tungsten scheelite by soviet - solvent extraction - evaporation and crystallization method;
5. Tungsten scheelite soda fluoride autoclave - ion exchange - evaporation crystallization;
6. Pressure cooking tungsten scheelite by soda fluoride autoclave - solvent extraction - evaporation and crystallization method;
7. Decompose tungsten scheelite by hydrochloric acid - ammonia dissolution - evaporation crystallization.