China has the most tungsten reserves in the world, occupying an important position in China's metallurgical industry. Ammonium paratungstate is the main raw material for metal tungsten production. Now extraction and ion exchange process are widely used in factories. The former one is that removing silicon, phosphorus, arsenic step by step after alkali boiling (or alkali fusion) of tungsten concentrates, adding Na2S make Mo become MoS3 precipitation, and then the supernatant was adjusted to pH 2-3, and extracted with a tertiary amine. Stripping with NH4OH. Therefore, to clarify the slot will go through stages of pH = 6. APT will then crystallize resulting in difficulty to normal operation. This problem is difficult to resolve from the formula, it is by strengthening stirring to dissolve the crystals again clarified or improved groove geometry of the internal structure of the practice. Although not required in addition to the ion exchange method P, As, Si but can not remove molybdenum, it is often the choice of Mo-containing low amounts of tungsten concentrate certain specifications. Although this method can be used directly with an alkaline feed solution, but due to the exchange a small amount of the material must first be diluted to contain WO3 25g / L or less, plus the rinse water is also large, and therefore of alkaline wastewater emissions pH10-13 Very large, wastewater treatment has become a burden, and waste water of these two methods can not be recovered in tungsten.

 

The concept emulsion film is N.N.Li proposed in 1968, it has attracted researchers States. Because it simulates the activity of migration biofilm on the migration mechanism enables highly enriched material against the concentration difference. It is the combination of extraction and back-extraction process carried out in a system where the same time, the reaction on the surface area is extremely thin film interface, plus the addition of a supported membrane, so its kinetic advantages far The reaction solution is better than the body conducted the mass transfer rate, efficiency and selectivity than the extraction process. This new technology is currently developing a forward unit operations, the international industrial application is first started University of Graz, Austria, for the recovery of zinc from waste water, followed by the Institute of Environmental Science, South China University of Technology for the removal of phenol wastewater.