Ammonium paratungstate (or APT) is a white crystalline salt of ammonium and tungsten, with the chemical formula (NH4)10(H2W12O42)·4H2O.

 

Ammonium paratungstate is produced by separating tungsten from its ore. Once the ammonium paratungstate is prepared, it is heated to its decomposition temperature, 600 °C. Left over is WO3, tungsten(VI) oxide. From there, the oxide is heated in an atmosphere of hydrogen, reducing the tungsten to elemental powder, leaving behind water vapor. From there, the tungsten powder can be fused into any number of things, from wire to bars to other shapes.

 

With the continuous development of China's tungsten industry, tungsten  resources get fewer and fewer. As, F and other elements were exploited, associated with the main elements of W, of which the posterior segment of the treatment process, resulting in arsenic fluorine wastewater. As exists mainly as the form of arsenate and arsenite ions. As compounds are carcinogens, trivalent arsenic is the most toxic , such as arsenic (As2O3). Chronic arsenic poisoning goes into the digestive system mainly through the diet , making people lose appetite, diarrhea and constipation alternately, indigestion, hepatomegaly, or even cirrhosis. F is one of the essential trace elements, the appropriate amount of F is beneficial to human health, but too much can cause fluorosis, such as dental fluorosis and skeletal fluorosis and other ailments, and even induce tumors.

 

An ammonium paratungstate (APT) production line with an annual output of 3 000 t has been built in Yunnan, which was put into production in 2009. Currently, production of 1 t of ammonium paratungstate products produced 4 t ~ 5 t of wastewater, therefore process of ammonium paratungstate wastewater treatment must be explored to meet current production needs.