Scheelite Concentrate Green Smelting Scheme

In China's tungsten reserves, scheelite is 70.4% and wolframite accounts for 29%. But for a long time, scheelite is seldom used because of its complex composition, low grade and difficult mining. With the development of technology, more and more scheelite mining methods are applied.

At present, scheelite concentrate is mainly blended with wolframite concentrate by high-pressure alkaline boiling technology. However, when scheelite is blended with wolframite, the total calcium content should be strictly controlled not to exceed 7%, resulting in low utilization of scheelite. Existing scheelite smelting technologies, such as mixed acid decomposition, ammonium salt decomposition, roasting decomposition, still have some problems, which remain in the experimental stage for the time being. Therefore, it is particularly important to develop new scheelite smelting technology which is expected to form industrial application, and it is also an important strategy for the sustainable development of China's tungsten industry.

In view of the shortcomings of the existing scheelite smelting process, some researchers have used inorganic acid and anion exchange resin to decompose scheelite, which can transform the scheelite into ionic state. This method solves the problem that the decomposition rate of scheelite is affected by the encapsulation of scheelite by tungstic acid in the traditional acid decomposition process. The main contents are:

10g scheelite (containing WO₃ 49.75%, Ca 8.72%), D301 resin pretreated with 6.6g, 800mL water added to 2L reaction vessel, stirred and heated to 40 ℃ for holding temperature, and gradually added 3 mol/L HCl. The pH value of the reaction system was controlled from 1.5 to 2.0, the reaction time was 6 h. After the reaction, the resin was vacuum filtered with water pH=2.5. After washing, 20% of the ammonia was desorbed and the desorption solution was sent to ICP. The decomposition rate of tungsten was 98.2%.

The key of technical scheme is that inorganic acid and anion exchange resin play a synergistic role in promoting the decomposition process of scheelite. When inorganic acid is used alone to decompose scheelite, the acid concentration required is particularly high, such as the traditional acid decomposition acid concentration of 14 mol / L, resulting in equipment corrosion, resulting in a large number of acid fog pollution of the environment; at the same time, the decomposition efficiency of scheelite caused by the decomposition of tungstic acid on the surface wrapping effect is not high. Using anion exchange resin and inorganic acid together, the acid decomposes scheelite and forms ionic tungsten which is absorbed and dispersed by resin coordination in time, thus effectively avoiding the wrapping effect of tungstic acid on the surface of scheelite, promoting the rapid decomposition of scheelite and improving the decomposition efficiency.

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