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<p>Although copper smelter dust (CSD) is classified as hazardous waste, it also serves as a valuable secondary resource, offering potential for the recovery of critical elements. In this study, CSD samples were collected from the waste heat boiler (WHB) and electrostatic precipitator (ESP) units connected to the flash smelting furnace at a copper smelter. The representative samples were extensively characterized by particle size, and chemical and mineralogical analyses. Following sample characterization, leaching experiments were performed to evaluate the potential extraction of Cu, Fe, As, Zn, Pb, In, Ga, and Ge from the flue dusts. Distilled water, H<sub>2</sub>SO<sub>4</sub>, and HCl were employed as lixiviants. The characterization results showed that 80% of the particles by weight in WHB and ESP samples were smaller than 104&#xa0;μm and 46&#xa0;μm, respectively. The WHB sample comprised 23.3% Cu, 20.3% Fe, 7.2% S, 1.8% As, and 1.5% Pb, whereas the ESP sample contained 21.2% Cu, 15.9% Fe, 1.8% As, and 1.5% Pb. The concentrations of Ga, Ge, and In were relatively low and nearly identical in both samples, measuring 6 ppm, 33 ppm, and 18 ppm, respectively. TIMA analysis indicated that the WHB and ESP samples were predominantly composed of CuFe sulfates (25–43 wt%), FeCu oxides (11–16 wt%), FeCu and CuFe silicates (13–28 wt%), and Cu sulfates (10–13 wt%). Additionally, Fe-Cu silicate phases served as the primary host for Ga, Ge, and In in both samples. The leaching efficiencies obtained in water for WHB sample were 43% for Cu, 35% for Zn, and 72% for Cd. In comparison, the ESP sample exhibited higher leaching efficiencies, with values of 62% for Cu, 50% for Zn, and 80% for Cd. Meanwhile, the leaching efficiencies for the rest of target elements in both samples were under 12%. Under high acid concentrations, the WHB and ESP samples demonstrated nearly complete extraction of Cu, As, Cd, and Fe at over 90%, while also achieving high leaching efficiencies for trace elements, with Ga at 75–82%, Ge at 84–86%, and In at 90–93%. Implementing a water pre-leaching stage reduced solid residue mass by 40–50% and yielded a pregnant leach solution enriched with 10,700–14,200 mg L⁻<sup>1</sup> Cu, 101–180 mg L⁻<sup>1</sup> Cd, and 193–294 mg L⁻<sup>1</sup> Zn, facilitating simplified downstream purification for critical elements.</p> Graphical Abstract <p></p>

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Characterization and Leaching Feasibility Studies of Copper Flue Dust for the Recovery of Main and Trace Metals

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年7月10日

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  • Fardis Nakhaei,
  • Marek Locmelis,
  • Lana Alagha,
  • Michael Moats,
  • Carlos Eyzaguirre,
  • Cory Smith

摘要

Although copper smelter dust (CSD) is classified as hazardous waste, it also serves as a valuable secondary resource, offering potential for the recovery of critical elements. In this study, CSD samples were collected from the waste heat boiler (WHB) and electrostatic precipitator (ESP) units connected to the flash smelting furnace at a copper smelter. The representative samples were extensively characterized by particle size, and chemical and mineralogical analyses. Following sample characterization, leaching experiments were performed to evaluate the potential extraction of Cu, Fe, As, Zn, Pb, In, Ga, and Ge from the flue dusts. Distilled water, H2SO4, and HCl were employed as lixiviants. The characterization results showed that 80% of the particles by weight in WHB and ESP samples were smaller than 104 μm and 46 μm, respectively. The WHB sample comprised 23.3% Cu, 20.3% Fe, 7.2% S, 1.8% As, and 1.5% Pb, whereas the ESP sample contained 21.2% Cu, 15.9% Fe, 1.8% As, and 1.5% Pb. The concentrations of Ga, Ge, and In were relatively low and nearly identical in both samples, measuring 6 ppm, 33 ppm, and 18 ppm, respectively. TIMA analysis indicated that the WHB and ESP samples were predominantly composed of CuFe sulfates (25–43 wt%), FeCu oxides (11–16 wt%), FeCu and CuFe silicates (13–28 wt%), and Cu sulfates (10–13 wt%). Additionally, Fe-Cu silicate phases served as the primary host for Ga, Ge, and In in both samples. The leaching efficiencies obtained in water for WHB sample were 43% for Cu, 35% for Zn, and 72% for Cd. In comparison, the ESP sample exhibited higher leaching efficiencies, with values of 62% for Cu, 50% for Zn, and 80% for Cd. Meanwhile, the leaching efficiencies for the rest of target elements in both samples were under 12%. Under high acid concentrations, the WHB and ESP samples demonstrated nearly complete extraction of Cu, As, Cd, and Fe at over 90%, while also achieving high leaching efficiencies for trace elements, with Ga at 75–82%, Ge at 84–86%, and In at 90–93%. Implementing a water pre-leaching stage reduced solid residue mass by 40–50% and yielded a pregnant leach solution enriched with 10,700–14,200 mg L⁻1 Cu, 101–180 mg L⁻1 Cd, and 193–294 mg L⁻1 Zn, facilitating simplified downstream purification for critical elements.

Graphical Abstract