# Extraction of tungsten from mine tailings: LDH-and EDTA-assisted scheelite dissolution

Farah Ajami, Domitille Giaume, Grégory Lefevre

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Farah Ajami, Domitille Giaume, Grégory Lefevre. Extraction of tungsten from mine tailings: LDH-and EDTA-assisted scheelite dissolution. Goldschmidt 2023, Jul 2023, Lyon, France. hal-05308617

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Submitted on 10 Oct 2025

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# Extraction of tungsten from mine tailings: LDH- and EDTA-assisted scheelite dissolution

Farah AJAMI, Domitille GIAUME, Grégory LEFEVRE

PSL Research University, Chimie ParisTech — CNRS, Institut de Recherche de Chimie Paris, 75005, Paris, France

The ANR VARTA project (VALorization and Remediation of TAilings of W-ores) aims to minimize the environmental impact of mine tailings while reducing European dependence on the critical resources of tungsten. The goal is to carry out the solubilization of scheelite mineral (CaWO₄) in order to extract the tungsten in mild acid solutions using a Layered Double Hydroxide (LDH) as anion exchanger.

Thus, the uptake of polytungstates anions can be performed using an LDH with Mg-Al layers, initially intercalated with carbonate ions. In a second step, the tungsten can be released in alkaline conditions, due to the instability of the polyanions species. Moreover, the addition of ligands with an affinity for Ca also promotes the dissolution of scheelite [1]. Both these mechanisms allow to increase the scheelite solubility and the dissolution rate, and they have been investigated by batch experiments, solid and solution characterization, and thermodynamic modelling.

<figure><img src="image_3.png" /><figcaption>**Fig. 1** Schematic representation of scheelite solubilization (on the left) and tungsten recovery (on the right).</figcaption></figure>

## References:

[1] G. Lefèvre, J. Lion, A. Makolana, « Extraction of tungsten as polyoxometalate anion using a layered double hydroxide: Selectivity and regeneration », *Sep. Sci. Technol.* 53, 1-10 (2018)

[2] Y. Konishi, H. Katada, et S. Asai, « Leaching kinetics of tungsten from low-grade scheelite ore in aqueous Na₄EDTA solutions », *Hydrometallurgy*, 23, 141-152 (1990)