Yellow tungsten oxide producing tungstate is dissolving yellow tungsten oxide in an alkali metal hydroxide or carbonate solution to produce alkali metal tungstate. In addition, if tungsten trioxide is melted with a metal oxide or carbonate, it can also get the corresponding tungstate. Such as:
WO3+NaOH = Na2WO4+H 2O
One possibility of yellow tungsten oxide (tungsten trioxide) producing tungstate is recycling waste tungsten oxide which contains scrap, or the quality can not meet the requirements and must be reworked to improve the quality indicators of substandard products, the recovery of products in general is ammonium tungstate. The principle of recycling waste tungsten oxide is tungsten oxide easily dissolved in high temperature and pressure of ammonia and generated ammonium tungstate solution, the steps are as follows:
1. The waste tungsten trioxide firstly go through the 60~80 mesh sieve, remove the agglomeration of tungsten oxide and mechanical inclusions, and then crush the agglomerated tungsten oxide to sieve them all;
2. Mix the waste tungsten trioxide and ammonia according to the ratio of 150~350 g/L, wherein, the content of ammonia in ammonia water is 8~20%;
3. Then carry out ammonia pressure cooking process in the high-pressure reactor for generating ammonium tungstate solution, and then cooling, filtration, to complete recovery process of ammonium tungstate.
Tungstate is a kind of salt which the anion contains contains tungsten acid radical (WO42-) or poly tungsten acid radical (W7O246-), a series of stable tungstate. Ammonium ions, alkali metals, alkaline earth metals ions and many heavy metal cations can form tungstates, whose general chemical formula is M2WO4 or NWO4 (wherein M represents the monovalent metal, and N represents a divalent metal). In addition to alkali metals, ammonium and magnesium tungstate, majority of it is insoluble in water.