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Hydrometallurgical processing of secondary raw materials (SRM)

Electro-leaching / electroplating of solid waste

Most hydrometallurgical waste management processes are costly because they involve many stages, the main ones being leaching and metal recovery through electrolysis.

After showing that it was possible to couple these two operations within the same cell (electro-leaching/electroplating) on a synthetic ZnO/SiO2 matrix, the process was successfully applied to two zinciferous waste products (Waelz oxides and ground down Zn/MnO2 batteries).

Current studies focus on the possibilities of re-using other metals (Cd, Ni, Co, Cu, etc.) present in various matrices (ground down accumulators, metallurgical slag, etc.) through the in situ generation of leaching reagents or a direct electrode reaction in the case of electroactive solids.

We are working on this subject in close collaboration with the ENSIC's Laboratory of Reactions and Process Engineering's electrochemical engineering team.

 

The electro-leaching / electroplating coupling principle
Pilot Cd(C10)2 precipitation reactor

Selective precipitation

Chemical precipitation is widely used in hydrometallurgy to either recover metals of interest or purify leachates before electrolysis.

Since 1999, the groupt has been studying the possibility of using odium carboxylates as precipitation reagents.

These reagents are non-toxic and biodegradable and are made of carboxylic acids from agro-resources. Previously acquired data means that now precipitation can move on to the pilot stage (in collaboration with the LRGP) for a medium-term technology transfer project.

From a more fundamental research standpoint, we are studying the influence of carbon chain branching, the presence of unsaturations or the size of the solvated cation on the value of solubility products.

This should enable us to establish a property-structure relationship to estimate the pKsp of any carboxylate for a given end-use.

Récupération de l’indium issu de la lixiviation des déchets électroniques

Certains liquides ioniques hydrophobes peuvent se substituer aux solvants organiques en extraction liquide/liquide.

Toutefois, la réextraction des espèces métalliques du liquide ionique s’avère ensuite difficile.

L’électrodéposition consécutive à l’extraction permettrait de résoudre ce problème.

De plus, grâce à la grande stabilité électrochimique des liquides ioniques, de nombreux éléments pourraient être récupérés sous leur forme métallique.

La faisabilité de ce procédé a été établie pour l’indium, métal rare considéré comme critique en raison des faibles ressources primaires et d’une demande en augmentation constante (écrans LCD, LEDs…).

Ces travaux sont réalisés en collaboration avec le Laboratoire de Chimie Moléculaire et Environnement (Polytech’ Savoie).