  Tungsten is a critical raw material for European and U.S. economies. Tungsten
mine residues, usually considered an environmental burden due to e.g. arsenic
content, are also secondary tungsten resources. The electrodialytic (ED)
process and deep eutectic solvents (DES) have been successfully and
independently applied for the extraction of metals fromdifferent complex
environmentalmatrices. In this study a proof of concept demonstrates that
coupling DES in a two-compartment ED set-up enhances the removal and separation
of arsenic and tungsten from Panasqueira mine secondary resources. Choline
chloride with malonic acid (1:2), and choline chloride with oxalic acid (1:1)
were the DES that in batch extracted the average maximum contents of arsenic
(16%) and tungsten (9%) from the residues. However, when ED was operated at a
current intensity of 100 mA for 4 days, the extraction yields increased 22% for
arsenic and 11% for tungsten, comparing to the tests with no current. From the
total arsenic and tungsten extracted, 82% and 77% respectively were
successfully removed from the matrix compartment, as they electromigrated to
the anolyte compartment, from where these elements can be further separated.
This achievement potentiates circular economy, as the final treated residue
could be incorporated in construction materials production, mitigating current
environmental problems in both mining and construction sectors.
