Sodium Tungstate Solution Purification by Magnesium Salt Precipitation

The NaOH decomposition process is currently used by tungsten smelting enterprises in China. During the process of decomposition, impurities such as phosphorus, arsenic, silicon, tin and fluorine will be decomposed into sodium tungstate solution. A large number of impurities will interfere with the subsequent processing, resulting in heavy task of subsequent purification process, resulting in low recovery rate of tungsten and even affecting the quality of subsequent ammonium tungstate and smelting wastewater treatment.

A solution of sodium tungstate with high impurity content is usually used in chemical precipitation. The effect of this method or synthesis is not good, or a large number of anions (such as chloride, sulfate, nitrate, etc.) will be introduced. The adsorption capacity of these anions will seriously affect the subsequent ion exchange process of tungsten, the impurity cation introduced at the same time, easily lead to ammonium paratungstate cation elements exceed the standard. Therefore, in the process of hydrometallurgy of tungsten, the method for purifying sodium tungstate solution with high impurity content needs to be improved.

Magnesium salt precipitation is an effective way to purify sodium tungstate solution. It can not only remove impurities such as fluorine, phosphorus, arsenic and silicon, but also do not bring impurity anions and cations to the tungstate ion exchange and product purity. After treatment, the content of fluorine, phosphorus, arsenic and silicon in sodium tungstate solution is greatly reduced.

The main process of magnesium salt precipitation method is to adjust the pH value of the sodium tungstate solution at 50-100 ℃, so as to precipitate silicon and obtain sodium tungstate mixed solution containing silicon precipitation. A mixed solution of second sodium tungstate was obtained by adding magnesium salt into the mixed solution of sodium tungstate. Under the condition of not less than 50 degrees Celsius, the mixed solution of third sodium tungstate was continuously stirred to obtain a mixed solution of third tungstic acid containing precipitation. At last, the third sodium tungstate solution is filtered to get the filtrate, and the filtrate is the purified sodium tungstate solution.

Using magnesium salt precipitation method can not only remove impurities such as fluorine, phosphorus, arsenic and silicon, but also do not introduce impurity anions and cations to tungstate ion exchange and product purity, so it is a simple and effective purification method.

• < Prev
• Next >