Ion Exchange Tungsten Molybdenum Separation

Molybdenum is a strictly controlled impurity element in tungsten products. China's national standard GB10116-88 stipulates that molybdenum is not more than 20ppm in the 0 grade ammonium paratungstate. At the same time, tungsten is also a strictly controlled impurity element in molybdenum products. The national standard GB/T3480-2007 stipulates that MSA-0 grade molybdenum acid is not more than 150ppm in the product.

In the range of pH = 6.5-8.0, the WO₄^2- ions in the solution can be polymerized into HW₆O₂₁^5- ions, while molybdenum in the solution still exists in the form of MoO₄^2-. The difference between the properties of HW₆O₂₁^5- ions and MoO₄^2- can be used to achieve the effective separation.

The technical scheme of the separation of tungsten and molybdenum by ion exchange method is that the mixed solution of tungstate and molybdate is adjusted to 6.5-8.0 by inorganic acid solution pH. According to the difference of Mo/WO₃ in the mixed solution of tungstate and molybdate, Cl- to 1g/L to 35g/L in the solution is adjusted by NaCl or NH₄Cl, and the 1.0-48 hour is placed in the solution, and the above solution is all at all speed. Flow through the ion exchange column with large pore and strong basic anion exchange resin, the contact reaction time of the material liquid and the resin is 30min-240min. When the mass concentration of tungsten in the liquid reaches the 5%-20% concentration of the raw tungsten in the liquid, the feed is stopped, and then the concentration of Cl- is 0.5mol/L-1.0mol/L. The drenching agent rinsed the resin in the ion exchange column to rinse the MoO42- ions adsorbed by the resin. Finally, the NaCl and NaOH mixture or the NH₄Cl and NH₃ mixture were used as the analytical agent to analyze the tungsten adsorbed on the resin and to regenerate the resin for the next production cycle.

With a mixture of Mo30g/L, WO3 6.0g/L sodium tungstate and sodium molybdate, after adjusting the solution pH = 6.5 with 18% hydrochloric acid, the concentration of Cl- in the solution is 5g/L, the contact reaction time of the mixture of 15 x 300mm with D201, the contact reaction time between the liquid and the resin for 90min. When the volume of the material is 5 times the volume of the resin in the two exchange columns, the exchange is stopped, and then the first ion exchange column is washed with the NaCl solution of 1mol/L of the resin volume in the single ion exchange column, the solution is merged with the exchange liquid to get the solution of Mo 22.5g/L, containing W in the solution. O3 0.35g/L. The first ion exchange column was analyzed with 5mol/LNaCl and 2mol/L NaOH solution containing 2 times the volume of resin in a single ion exchange column. The high tungsten low molybdenum solution contained WO₃ 18.5g/L and Mo 1.6g/L.

The ion exchange resin used in this method is easy to analyze and it is easy to regenerate, and the process is simple, low cost, good separation effect and no pollution to the environment. It is a more common method.

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