Recovery of Copper from Ammoniacal Leachates by Ion Flotation

Abstract

Sulfidic copper−lead−zinc tailings can pose a significant environmental threat, ranging from generation of acid mine drainage (AMD) to dam failures. On the other hand, they can also be considered as low-grade ore resources for zinc and copper provided that novel economically feasible metal extraction and metal recovery techniques are developed. Due to the low metal concentrations in these resources, the leaching will generate dilute leachates from which metal recovery is a challenge. Ion flotation is a foam separation technique capable of recovering metal ions from dilute aqueous leachates. In this paper, ion flotation was applied to separate copper from ammoniacal leachates of microwave-roasted sulfidic tailings samples. The sulfidic tailings were first roasted at 550 °C for 60 min, for the oxidation of sulfide minerals to more easily soluble sulfates using microwave assisted irradiation as heating source. The microwave-roasted material was then leached with a mixture of ammonia and ammonium carbonate solutions. The optimum leaching efficiencies of zinc (86%) and copper (75%) were obtained under the following conditions: liquid-to-solid ratio = 10 mL g -1 , T = 90 °C, [NH3+NH4 + ] = 4 mol L -1 , NH3:NH4 + = 2:1, t = 5 h. From the generated pregnant leach solution, it was possible to selectively separate 85% of copper to the foam phase by ion flotation, with sodium dodecyl sulfate (SDS) surfactant, as colloidal tetraammine copper(II) dodecyl sulfate under the optimized conditions: [SDS]total = 5.85 mmol L -1 , [EtOH] = 0.5 % (v/v), ttotal = 5 h, flotation stages = 3. The zinc that remained in the solution after ion flotation was recovered by precipitation (95%) as basic zinc carbonate.

Preface to the Thematic Section: Mine Tailings: Problem or Opportunity? Towards a Combined Remediation and Resource Recovery Approach

“…Six papers of the thematic section are dedicated to different aspects of the characterization, metal extraction, and valorization of the mineral fraction of the Neves Corvo extractive waste [6][7][8][9][10][11][12]. Neves Corvo is an underground Cu-Zn mine located in Southern Portugal.…”

“…Everaert et al (this issue) apply an alternative method to recover target metals: they explore a roasting process followed by ammoniacal leaching [9]. Subsequently, Xanthopoulos et al (this issue) use ion flotation techniques for the recovery of copper from ammoniacal leachates [10]. In a subsequent step, ion tion collectors are regenerated and reused in the next ion flotation cycle [11].…”

Recovery of copper, zinc and lead from photovoltaic panel residue

“…In a previous study by the authors it was proven that the addition of extra dosages was beneficial for the overall recovery efficiency of the colligend. 50 …”

“…The material was also characterized by XRD using the McCrone method. 50 More specifically, 1.8 g of sample were mixed with 0.2 g of rutile (TiO 2 ), which was used as internal standard. The solid mixture was then homogenized by adding ethanol and milled for 5 min in a McCrone micronizing mill.…”

Exploring the Potential for Utilization of Medium and Highly Sulfidic Mine Tailings in Construction Materials: A Review

“…The oxidation of sulfide minerals can also take place as a result of thermal treatments, as observed in tailings subjected to roasting [59,108]. Unlike calcination, roasting is carried out at lower temperatures, typically half of those used in calcination, and mostly in sulfidic ores.…”