Tungsten and Molybdenum Separation from Tungstate and Molybdenum Mixture

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.

In order to remove molybdenum in tungstate solution, the MoS₃ precipitation method was used in the past, the effect of molybdenum was not good enough to pollute the environment with H₂S gas. A new method of precipitation and separation of tungsten and molybdenum from the mixed solution of tungstate and molybdate was recently proposed, which could be used in the production of tungsten and molybdenum products in the existing tungsten and molybdenum smelting process. The mixture of tungstate and molybdate is adjusted to pH value of 7.0-12.0, and precipitate is added to it to make precipitation with tungsten. After liquid-solid separation, molybdate and tungsten rich slag are obtained, and tungsten rich residue is recovered by alkaline solution. The specific cases are as follows:

Sodium tungstate, sodium molybdate mixed solution 5L, containing Mo 2g/L, WO₃ 6.0g/L, pH = 12. Under the condition of room temperature and stirring speed of 150rpm, the required reagents were added 2 times the amount of rational theory and slowly added manganese sulfate 39G (added into 200-300g/L manganese sulfate solution), then continued to be stirred for 5 hours to filter, the filtrate contained Mo 1.8g/L, WO₃0.4g/L. Adding 1.2 times NaOH, 12g, adding 200ml water in the tungsten rich slag, filtrating in the autoclave at 120°C for 2 hours,containing WO₃ 138g/L, Mo 4.6g/L in the filtrate. In the manganese slag, 1.5 times of the theoretical amount added to 50% sulphuric acid 38ml, then adding water 50ml, stirring at room temperature for 30 minutes, the precipitation is completely dissolved, it can be used as the precipitant of tungsten and molybdenum separation.

The method is easy to implement, low cost and. It is suitable for the removal of a small amount of molybdenum in tungsten and tungstate solution in molybdate solution, the solution after impurity is used in the production of tungsten and molybdenum products, thus realizing the connection with the existing tungsten and molybdenum smelting process, which is suitable for the production of different tungsten and molybdenum content.

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