At present, the recovery and processing of tungsten waste has become a large scale, forming industry, mainly using tungsten waste to treat the sodium tungstate with wet process. This method has a large amount of treatment and is widely used for the tungsten containing waste. However, this method has serious pollution to the environment and the process is more complex.

Selective catalytic reduction (SCR) technology and its key equipment denitration catalyst industry have been vigorously developed for the treatment of thermal power plants. Vanadium tungsten (molybdenum) titanium catalyst is the most widely used SCR denitration catalyst in SCR technology.

At present, there are two methods for the production of ammonium paratungstate. First, the industrial sodium tungstate solution is first made to make white tungsten, then the concentrated acid is made into tungstate under the condition of heating and cooking. Then tungstate is made into ammonium paratungstate. The industrial sodium tungstate solution through anion exchange resin and then rinse with concentrated ammonium chloride, so that tungsten is made into ammonium tungstate. Then, the tungsten is made into ammonium tungstate. It is evaporated into ammonium paratungstate. Both of two methods have no molybdenum removal. To achieve the purpose of removing molybdenum, or to reduce the crystallization rate of ammonium paratungstate to 70-80%, the mother liquid should be removed from molybdenum after reducing the crystallization rate.

Molybdenum and tungsten are strictly controlled impurities in tungsten and molybdenum metallurgical products. The national standard GB10116-88 of our country stipulates that molybdenum is not more than 20ppm in the 0 grade ammonium paratungstate, the national standard GB/T3480-2007 stipulates that MSA-0 molybdenum acid is not more than 150ppm in the product. When dealing with molybdenum scheelite, waste catalyst and other raw materials, they are faced with the task and difficult problem of separating tungsten from molybdenum in solution.