APT Acid Decomposition Preparing Tungstic Acid
APT acid decomposition to prepare tungstic acid is a process to manufacture tungstic acid which is less used compared to other method.
Some literatures have pointed out the way by acid decomposition of ammonium paratungstate (APT) or ammonium tungstate (NH4)2WO4), however because the acid decomposition of NH4)2WO4 solution will produce a lot smoke of NH4Cl with a very violent reaction, and thus to require high in equipment, consuming large number of acid and polluting the environment in severe and other disadvantages; in addition, the solubility of APT is really small, and hard to be decomposed completely, so the method is rare used in industrial. Researchers in Japan has modified this synthesis process by changing the state of APT to greatly improve acid decomposition efficiency and tungstic acid quality, and now is used in the manufacture of high purity of tungstic acid used in tungsten wire for integrated circuit.
But what is worth noting is that APT is the main raw material for manufacturing tungsten carbide, the way to directly prepare APT from tungsten concentrate is variety, in addition to ammonia crystallization method, there are mainly ion exchange and extraction method which are often used, furthermore, the ion exchange and extraction method presents the new direction of tungsten metallurgy basically.