Zinc recovery from an extreme copper-free acid mine drainage: studying the prior separation of ferric iron by solvent extraction using AliCy and/or alkalinization

Nobahar, Amir; Melka, Alemu Bejiga; Marín-Beltrán, Isabel; Neves, Luiz; Costa, Maria Clara; Dias Carlier, Jorge

http://hdl.handle.net/10400.1/18725

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Authors

Nobahar, Amir

Melka, Alemu Bejiga

Marín-Beltrán, Isabel

Neves, Luiz

Costa, Maria Clara

Dias Carlier, Jorge

Abstract(s)

Zn recovery attempts from a copper-free extreme Acid Mine Drainage with similar to 53 g/L Fe and similar to 2 g/L Zn revealed Fe co-extraction in solvent extraction with 0.9 M D2EHPA or a mixture of 0.72 M D2EHPA and 0.18 M Cyanex 272, and simultaneous precipitation of Fe during zinc sulfide recovery through biogenic sulfide addition. Therefore, alkalinization, solvent extraction with the self-prepared ionic liquid AliCy diluted in kerosene, and combinations of both these methods were studied for the separation of ferric iron (Fe3+) from such water, prior to Zn recovery. The most efficient strategy tested was a solvent extraction cycle with AliCy followed by alkalinization of its aqueous raffinate to pH 3.25 or 3.5. As a result of this approach, similar to 92% of Fe3+ is separated by SX and the remaining is removed by precipitation, with just similar to 12% or similar to 17% Zn losses, respectively. Afterwards, the highest Zn recovery from water resulting from such combination of processes was achieved by precipitation through addition of biogenic sulfide at pH = 3.5. The obtained precipitates are nanoparticles of Wurzite and Sphalerite (ZnS) of sizes between 2 to 22 nm agglomerated into larger structures. This work shows for the first time the potential of AliCy to separate Fe3+ from acidic multimetallic solutions, a known contaminant of several metal recovery processes.