Separation of Molybdenum in Production Process of Ammonium Paratungstate

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.

Separation of tungsten and molybdenum in production process of ammonium paratungstate is an important working procedure, but this is always one of difficult technical problems. General flows of various ammonium paratungstate technologies and the basic nature of molybdenum were summarized. Moreover, advantages and disadvantages of each separation method for tungsten and molybdenum in production process of ammonium paratungstate were systematically analyzed. Analysis results indicated that there are many advantages, such as short process flow, small tungsten loss, good molybdenum eliminating effect, simplicity of operation, low environmental pollution, and economy feasibility to eliminate molybdenum by using ion-exchange method. It is precisely because of these advantages, ion-exchange method to eliminate molybdenum has a very good industrial application prospect.  

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