Valorisation options for Zn and Cu recovery from metal influenced acid mine waters through selective precipitation and ion-exchange processes: promotion of on-site/off-site management options

Acid mine waters (AMWs), generated in the processing of polymetallic sulphides, contain copper and zinc as the main valuable transition metal ions, which are typically removed by liming, due to their great environmental impact. In this context, this work proposes the integration of selective precipitation (SP) and ion-exchange (IX) processes for the separation and recovery of both valuable metals to encourage on-site and off-site management options promoting valorisation routes. Thus, the main objectives of this work were (i) the selective removal of Fe(III) and Al(III), using NaOH under pH control (pH 99%) and Al(III) (>90%) as hydroxylsulphates (e.g., schwertmannite and basaluminite). The metal extraction profiles were determined for both metals from pH 1 to pH 5 by batch experiments, and indicated that the best extraction of Zn(II) was obtained using VP1026, being higher than 96% (pH = 2.6–2.8), whereas TP207 extraction performance was optimal for Cu(II) extraction (>99%) at pH = 3–4. Moreover, in dynamic experiments using a fixed-bed configuration, it was possible to separate and concentrate Zn(II) (concentration factor = 10) and Cu(II) (concentration factor = 40) using VP1026 and TP207, respectively. Overall, the integration of SP and IX processes showed a great potential in the separation and recovery of valuable metals from mine waters to promote a circular economy, based on the management proposal for non-ferrous metallurgical industries. The recovered Zn-rich and Cu-rich sulphuric concentrated streams were theoretically evaluated for further on-site or off-site re-use treatments (e.g., electrowinning, precipitation, crystallization). •Selective precipitation and ion-exchange process integration for Zn and Cu recovery.•Fe (>99%) and Al (>90%) were removed as hydroxylsulphates in the precipitation step.•Zn separation by Lewatit VP 1026 resin (>96% extraction, CF = 10) at pH > 2.5•Lewatit TP 207 resin was used for Cu separation (>99% extraction, CF = 40) at pH > 3.•On-site/off-site managements were proposed for non-ferrous metallurgical plants.