Tungsten is an important rare metal, which is widely used in the fields of national defense, chemical industry, electronics and metallurgy. Solvent extraction has been widely used for tungsten recovery because of its simple operation, good continuity and high recovery rate. Previous researches have always focused on the development of new extractants while ignoring the role of tungsten ion morphology in the extraction process. In fact, ion morphology will affect the way of combining with the extractant and the extraction process. Therefore, in-depth study of ion morphology in the extraction process can better understand the extraction mechanism of tungsten, and thus provide a basis for the separation of tungsten and molybdenum. In this study, annular centrifugal contactors (ACCs) were combined with electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) to study the transformation pathway of tungsten species in the recovery process by online monitoring method. It was found that the extraction of tungsten by primary amine N1923 was very fast and effective. Within 144 s, more than 98% of the tungsten could be extracted into the organic phase. At the same time, n(H)/n(W) was a key variable. When the acid ratio was 2.4, the whole tungsten recovery rate exceeded 93%. Finally, the extraction mechanism based on tungsten morphology monitoring was obtained. The macroscopic extraction reaction and the micro-ion exchange reaction occurred simultaneously and complemented each other. As the initial pH decreased, W2, W6 and W10 became active forms in sequence and were preferentially extracted into the organic phase, respectively. In addition, W10 was more active than any other species during the whole process. W1 was an inactive substance that only participated in the tungsten ion balance reaction to adjust the tungsten form and pH. As a result, reducing W1 and increasing W10 as much as possible would be conducive to improve tungsten extraction efficiency in solution.
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