Bao Guo

Selective recovery of germanium from zinc-metallurgical sulfate liquors is hindered by excess dissolved silicon and by the need to avoid reagents that disrupt downstream zinc processing. Here, acid-washed, hydrothermally treated bentonite was modified with zirconium to create an inorganic mineral carrier for Ge capture at pH 1. Zr modification increased nitrogen uptake and pore volume while retaining the aluminosilicate framework. At 60 °C and 120 min, the highest measured Ge loading increased from 18.50 to 26.17 mg g⁻¹. In a synthetic multicomponent sulfate solution, Zr-AHT removed 53.29% Ge but only 2.49% Si and 1.01% Zn, yielding mean Ge/Si and Ge/Zn separation coefficients of 47.95 and 150.83. SEM–EDS and XPS identified Ge-bearing, Zr-containing recovered particles, while dissolved Zr remained at 0.270 mg L⁻¹ after the selected contact time. Sulfuric-acid desorption released 86.19% of the loaded Ge in the screening series and 90.74% when the primary eluate and two washes were included in an independent mass balance. Sulfation roasting at 200 °C followed by water leaching recovered 80.12%. These results establish a low-cost, sulfate-compatible mineral-carrier route for separating Ge from silicon-rich acidic media and transferring it to a recoverable solid.

Rapid screening of residual flotation collectors in complex aqueous systems is important for reagent control and process water management. However, spectral overlap, imbalanced SERS responses, and variability among surface-enhanced Raman spectroscopy hotspots complicate the simultaneous identification of multiple components. In this study, five representative flotation collectors, BHA, MBT, SBX, ETC, and BK25, were investigated using an electrodeposited Au NPs/ITO SERS substrate. A total of 540 SERS spectra obtained from 63 controlled sample compositions were used to construct a dataset with five collector labels. A group-aware multi-instance multi-label ensemble was developed for simultaneous collector screening. The framework first uses an adaptive label-specific binary relevance module to estimate label-specific instance probabilities for each collector. It then incorporates label relationships and performs protected multi-instance fusion of probability distributions, auxiliary local spectral region responses, and latent variable information derived from multiple SERS hotspots of the same sample, yielding a five-label presence vector. Under strict five-fold group-wise cross-validation, GMI-MLE achieved a subset accuracy of 0.857, Micro-F1 of 0.956, Macro-F1 of 0.952, and Hamming loss of 0.032. Exact five-label recovery was achieved for 54 of 63 samples, with 305 of 315 sample-label decisions correctly classified. Compared with the full spectrum binary relevance SVM baseline, GMI-MLE achieved exact recovery for eight more samples and reduced Hamming loss by 44.4%. BHA, despite its relatively weak SERS response, still achieved an F1-score of 0.986. These results show that label-specific modelling combined with multi-hotspot information fusion improves joint screening under spectral overlap and response imbalance, providing an analytical framework for rapid multicomponent SERS screening of known candidate collectors in complex aqueous systems.

The concentration-dependent role of Mn²⁺ in regulating the anodic behavior of Pb–Ag anodes was investigated in chloride-free acidic sulfate media relevant to zinc electrowinning. Cyclic voltammetry, 24 h galvanostatic polarization, electrochemical impedance spectroscopy, Tafel polarization, and SEM–EDS were combined to clarify the coupling among Mn²⁺ oxidation, Pb-based oxide transformation, oxygen evolution reaction, corrosion resistance, and trace impurity effects. Mn²⁺ markedly altered the anodic interfacial process by promoting the in situ formation of MnOₓ/PbOₓ composite oxide layers. In the Mn²⁺-free electrolyte, the Pb–Ag surface was mainly covered by a loose Pb-based oxide/sulfate layer with limited protection, leading to pronounced Pb dissolution. Introducing Mn²⁺ shifted the anode from active dissolution toward film-controlled behavior. The corrosion current density decreased from 1.25 × 10⁻³ A·cm⁻² without Mn²⁺ to 3.2 × 10⁻⁷ A·cm⁻² at 2 g·L⁻¹ Mn²⁺. Mn²⁺ also lowered the oxygen evolution potential by approximately 140 mV at 0.1 and 0.2 A·cm⁻², although the minimum oxygen evolution potential occurred at 3–4 g·L⁻¹ Mn²⁺. Impedance analysis revealed a non-monotonic response, indicating that film compactness, electronic/ionic transport, and interfacial resistance are jointly governed by Mn²⁺ concentration. Coexisting Fe, Co, Ni, Cu, and Sb ions further modified the electrochemical response by altering the defect structure and transport properties of the composite oxide layer. Overall, Mn²⁺ regulates Pb–Ag anode stability through a concentration-dependent balance among corrosion resistance, oxygen evolution activity, and interfacial transport. A concentration of 1.0–2.0 g·L⁻¹ favors corrosion suppression and film stability, whereas 3.0–4.0 g·L⁻¹ enhances oxygen evolution activity or interfacial impedance under specific conditions.

The concentration-dependent role of Mn²⁺ in regulating the anodic behavior of Pb–Ag anodes was investigated in chloride-free acidic sulfate media relevant to zinc electrowinning. Cyclic voltammetry, 24 h galvanostatic polarization, electrochemical impedance spectroscopy, Tafel polarization, and SEM–EDS were combined to clarify the coupling among Mn²⁺ oxidation, Pb-based oxide transformation, oxygen evolution reaction, corrosion resistance, and trace impurity effects. Mn²⁺ markedly altered the anodic interfacial process by promoting the in situ formation of MnOₓ/PbOₓ composite oxide layers. In the Mn²⁺-free electrolyte, the Pb–Ag surface was mainly covered by a loose Pb-based oxide/sulfate layer with limited protection, leading to pronounced Pb dissolution. Introducing Mn²⁺ shifted the anode from active dissolution toward film-controlled behavior. The corrosion current density decreased from 1.25 × 10⁻³ A·cm⁻² without Mn²⁺ to 3.2 × 10⁻⁷ A·cm⁻² at 2 g·L⁻¹ Mn²⁺. Mn²⁺ also lowered the oxygen evolution potential by approximately 140 mV at 0.1 and 0.2 A·cm⁻², although the minimum oxygen evolution potential occurred at 3–4 g·L⁻¹ Mn²⁺. Impedance analysis revealed a non-monotonic response, indicating that film compactness, electronic/ionic transport, and interfacial resistance are jointly governed by Mn²⁺ concentration. Coexisting Fe, Co, Ni, Cu, and Sb ions further modified the electrochemical response by altering the defect structure and transport properties of the composite oxide layer. Overall, Mn²⁺ regulates Pb–Ag anode stability through a concentration-dependent balance among corrosion resistance, oxygen evolution activity, and interfacial transport. A concentration of 1.0–2.0 g·L⁻¹ favors corrosion suppression and film stability, whereas 3.0–4.0 g·L⁻¹ enhances oxygen evolution activity or interfacial impedance under specific conditions.

Manganese is essential for zinc electrowinning but its recycling is challenging in oxide ore SX-EW circuits where P204 rejects Mn. This study proposes a novel manganese recycling strategy tailored for SX-EW streams involving the selective SO₂ reductive leaching of zinc anode slime followed by impurity removal. By controlling leaching pH at 5.0 with lime, Mn recovery > 92% while Fe, Ni, Co co-dissolution is suppressed to < 1%, 3%, 12% respectively. Residual impurities in the spent electrolyte are further removed by neutralization and DMDTC chelation. This integrated process effectively recovers manganese while simultaneously eliminating harmful impurities (Cu, Fe, Co, Ni), offering a sustainable solution for Mn management in complex oxide ore hydrometallurgy. The purified electrolyte enabled production of Grade #1 zinc with Pb < 0.005%.

In copper anode slime hydrometallurgical plant, Au and Ag are recovered by perchloric leaching and ammonia leaching, stepwisely and respectively. However, their recovery is incomplete with a significant amount of refractory Au/Ag remaining in ammonia leaching residue, encapsulated by PbSO ₄ and BaSO ₄ . These gold and silver can only be released by the removal of PbSO ₄ /BaSO ₄ , which can be realized by Na ₂ CO ₃ carbonation and the subsequent HCl leaching. In this work, a process flowsheet has been designed to recover Au/Ag in ammonia leaching residue and individual PbSO ₄ and BaSO ₄ products were also obtained with extra value. The cost of this process can be greatly reduced by Na ₂ CO ₃ recycling between the two-stage Ba carbonation and one-stage Pb carbonation with freezing crystallization of Na ₂ CO ₃ .