Decomposition Process of Wolframite in Mixed Symbiosis Ore

In many scheelite deposits in China, scheelite is not only associated with scheelite, but also with wolframite. For example, Xingluokeng, Fujian Province, is a super-large wolframite-scheelite deposit, with tungsten reserves of about 300,000 tons, and scheelite and wolframite reserves accounting for half of each.

At present, the main method of industrial decomposition of tungsten mineral raw materials is NaOH decomposition process, which must be under extreme conditions to achieve effective decomposition of tungsten ore. However, the tendency of thermodynamic reaction of acid decomposition of tungsten ore is very high, but the decomposition is often incomplete due to the kinetic constraints. Obviously, the traditional method can not deal with the decomposition of wolframite-scheelite mixed paragenetic ore, therefore, an effective combination scheme is also very important.

A method of extracting tungsten from wolframite-bearing raw materials has been put forward by some scholars. This method can decompose wolframite and wolframite-scheelite mixture efficiently at room temperature and atmospheric pressure, breaking through the limitation of sulfuric acid-phosphoric acid system which can not treat wolframite and wolframite-scheelite mixture. Their routines are as follows:

Wolframite concentrate with particle size less than 250 micron (including WO₃ 71.3%) and apatite (including P₂O₅ 35.81%) were blended and added to the ball mill. The ball milling reaction was carried out for 2 hours after adding water at a liquid-solid ratio of 0.5:1 mL/g. After the reaction was terminated, the wolframite concentrate was filtered and dried for 24 hours. The wolframite was partially converted into scheelite.

The tungsten ore was leached for 4 hours in a mixed acid solution with H₂SO₄ concentration of 250g/L and H₃PO₄ concentration of 300 g/L, and the liquid-solid ratio was 10:1 mL/g. The leaching rate of tungsten was 99.2%. After extraction of tungsten by tertiary amine extractant, mother liquor is added to the spent sulfuric acid to return to the new round of leaching. Under the same decomposition conditions, the leaching rate of tungsten is 99.1%.

For wolframite, the decomposition rate can reach 98% or more, and for wolframite-scheelite mixture it can reach 97%. The phosphorus-containing calcium material used in this method has a wide range of sources and low price, and phosphoric acid can be produced during decomposition, which can be used to make up for the phosphoric acid consumed in the decomposition process. The whole process is easy to operate and easy to realize industrialization.

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