Method for extracting and separating ions in two valence states of the same element in three phases

The invention relates to the technical field of extraction and separation, in particular to a method for extracting and separating ions in two valence states of the same element in three phases. The method comprises the following steps of: 1) adding water-soluble high polymer, inorganic strong polyelectrolyte salt and a coordinating agent in turn into aqueous solution containing the ions in two valence states of the same element, and fully mixing to obtain mixed solution; and 2) regulating the pH of the mixed solution in the step 1), adding an organic extracting agent immiscible with water, fully mixing, standing and centrifuging to obtain a liquid-liquid-liquid three-phase system with coexistent upper layer, middle layer and lower layer, wherein the upper layer is an organic phase, the middle layer is an aqueous phase of the high polymer and the lower layer is an aqueous phase of the inorganic strong polyelectrolyte salt, and the ions in the two valence states are respectively extracted into the upper, middle or lower layer to realize the extraction and separation of the ions in the two valence states of the same element. By the method, the same element in two valence states is finely separated, and the problem of low recovery rate in a liquid-liquid extraction process is solved.