Recycling and Reusing Ammonium Paratungstate Crystal Liquor 1/3

Ammonium paratungstate(APT) is the necessary transition state during the producing of tungsten.Ammonium paratungstate crystal liquor contain WO3 about 5%~15% during the process of crystallizing,and other impurities like:Mo、P、As and so on.It causes huge waste if we pour it out. Therefore,for manufacturers and researchers it became an important issue that how to recover and reuse the APT mother liquid.Choose a reasonable way of recycling process has a great effect on technology index and economic interests. There are three methods to recycle and reuse ammonium paratungstate crystal liquor as bellow:Remaining alkali decomposition,ion exchange,M115-a selective precipitation.
 
Method one:Ion Exchange
In the 1980s,people started to use ion exchange to produce ammonium paratungstate,and then it became a universal way for the advantages of shorter process,less investment,doing no harm to environment,higher yield.And the way to deal with ammonium paratungstate crystal liquor turned to ion exchange,the principle  is tungsten turn into complex anions in different PH,when ammonium paratungstate crystal liquorweak turns from alkali to acid,tungstate ions group into HW6O521, W12O639,H2W12O640 and so on.Ions like P、 As、Si、Mo combine with tungsten and become PW12O340 ,PMo12O340,AsW12O340,SiW12O440 .When it contact with the basic resin, reaction as follows:
6R3NHCl+H2W12O640= (R3NH)6H2W12O40+6Cl
Then desorpte with alkali, the following reaction occurs:
(R3NH)6H2W12O40+6NaOH=Na6H2W12O40+6(R3NH)OH
Na6H2W12O40+18 NaOH=12NaWO4+10H2O  
 
Ion exchange to deal with APT crystallization liquor can improve the tungsten recovery about 1.2%~2.0%.Whtn the solution leaves join in the main flow, the technology indicators will be stabile, and achieving better economic efficiency.It is a simple, economical and reasonable recycling process for tungsten APT crystallization from the mother liquor.
 

WeChat