"Acid Leaching" of Ammonium Paratungstate with Tungsten Waste

In the traditional method of producing ammonium paratungstate, the main impurity ions in tungsten waste are phosphorus ions, magnesium ions, iron ions and potassium ions. The major part of the tungsten waste is four kinds of phosphorus ions, magnesium ions, iron ions and potassium ions. At 50 -60°C, the large part of the phosphorus ions and potassium ions in the tungsten residue can not be precipitated, and the magnesium ions are also due to the magnesium ions. With the influence of iron ions, most of the tungsten slag produced will be lumpy when the reaction is finished.

Because the impurities contained in the tungsten slag are too much, after the forced oxidation, the final yield of tungsten oxide is still low, so the production method of the traditional tungsten waste is not only complicated, but also the waste of raw materials is more and the output is low.

Some scholars have improved the above methods. It does not need to soak and smash tungsten waste first, "acid leaching" is carried out directly at 95-110°C. The so-called "acid leaching" is the removal of impurities from tungsten wastes in a solution containing acid components. The specific operation of the scheme is as follows:

At the temperature of 100°C, the tungsten waste was pickled to obtain a solid liquid mixture.

（1） The solid-liquid mixture was separated from solid liquid at 80 -90°C and the initial slag containing tungsten was obtained.

（2） At the temperature of 105°C, the initial tungsten slag was acid soaked to get the two solid liquid mixture.
（3） The solid-liquid separation of the two solid-liquid mixtures was carried out at 80°C, and two times of slag containing tungsten was obtained.

（4） Two tungsten containing slag was put into a drying furnace with a temperature of 600 -700°C at the same time.

（5） The ammonium tungstate solution was prepared by mixing the tungsten oxide into a reactor with ammonia, copper sulphate powder and oxalic acid powder in a reactor with 110°C and 0.3 MPa pressure for 6 hours.

（6） Purified ammonium tungstate solution was purified to ammonium tungstate solution.

（7） At the temperature of 100°C, the ammonium tungstate solution was evaporated and crystallized and the ammonium partungstate product was prepared.

At 95 -110°C, the acid solution will reach the boiling point. In the range of the temperature, the impurity ions in the tungsten waste are more active, the impurity ion decomposition is more thorough, and the residual impurities in the tungsten residue after solid liquid separation are very few, and the final tungsten residue will not form a large block, and the most significant improvement is made. The quality of the final product.

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