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Application of the electrodialytic process for tungsten recovery and arsenic removal from mine tailings
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Mining tailings (MT) deposited in open dams can cause environmental problems. On the other hand, these residues can be seen as a secondary source of critical raw materials. The present dissertation is the first attempt to study the efficiency of the application of the electrodialytic process (ED) for tungsten (W) recovery and arsenic (As) removal from Panasqueria mine residues (Covilhã, Portugal).
Nine experiments were performed, some in duplicate, using cells with two (2C) and three (3C) compartments, in the presence of cation (CAT) and anion (AN) exchange membranes, with current intensities between 0 and 100 mA and durations between 7 and 14 days. The MT sample was placed in the central cell compartment in the 3C setup and directly in the anode or cathode compartment in a 2C cell.
The results show that the 2C cell setup with an AN presented the highest W recovery (0.15 %) and As removal (23.51 ± 21.33 %). When a CAT was applied to the same cell configuration, W and As migration from the sample to the electrolyte compartment was not verified, and no elements recovery or removal occurred. Further preliminary tests were carried out adding three adjuvants to the sample. The 2C cell setup with a CAT was applied since the 2C AN cell showed to be instable. When the adjuvant B was added, the recovery of W achieved 0.64 % and the removal of As 9.48 %.
The higher the current intensity applied the better the W recovery and the As removal obtained. However, W recovery was lower than the As due to the presence of sulfates in the sample that promote the formation of W complexes. Future experimental work should be carried out to optimize the ED conditions, not obtained in the present dissertation.
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Electrodialytic process Panasqueira mine tungsten arsenic critical raw materials remediation