有色金属(冶炼部分)

针对湿法炼锌净化阶段高钴溶液深度除钴难度大、锌粉消耗量高及传统固态除钴剂利用率低等问题，开展了基于辅料间歇式溶液化调控的两段净化除钴工艺优化研究。通过将硫酸铜和锑盐配制成特定浓度溶液，采用间断分批次给料方式处理一段净化后液，系统考察了锌粉、锑盐及硫酸铜的用量与投料模式对除钴效果的影响。结果表明，二段净化最优工艺条件为：反应温度85～90℃、时间2.0～2.5 h、锌粉用量4.0 g/L、10 g/L硫酸铜与2 g/L锑盐溶液按每10分钟加0.6 mL，共12次同步投加。该优化工艺可将净化后液钴含量稳定降至0.5 mg/L以下，满足后续电积要求，且锌粉单耗从每吨锌片70 kg显著降至约35 kg。结合扫描电子显微镜、X射线衍射及X射线光电子能谱分析，揭示了辅料的脱钴强化机制。在锌粉置换过程中，锑与钴、铜结合形成固态金属间化合物（如Co-Sb、Co-Cu相），有效固定钴离子并抑制返溶；同时，铜、锑在锌粉表面共沉积构建的Cu-Zn与Sb-Zn微电池体系，促使局部阴极电位负移，显著降低了钴的析出能垒并加速电子转移。该多批次溶液投料工艺有效避免了反应体系内的局部浓度梯度，大幅提升了锑盐的有效利用率，为解决实际工业高钴硫酸锌溶液的深度脱钴提供了切实可行的技术方案和理论支撑。

An investigation was conducted to optimize a two-stage purification process for deep cobalt removal from high-cobalt zinc sulfate solutions utilizing adjuvant regulation. Traditional purification methods exhibit high zinc powder consumption and low utilization efficiency of solid decobaltation agents. To resolve these procedural limitations, a method employing the intermittent solubilization and batch feeding of auxiliary materials was developed. Copper sulfate and antimony salt solutions were formulated at specific concentrations and applied to the effluent derived from the first-stage purification. The study systematically evaluates the variables influencing cobalt removal efficiency, including the dosage of zinc powder, the concentrations of antimony and copper salts, and the exact feeding patterns of these additives. The experimental results establish the optimal operating conditions for the enhanced second-stage purification. The optimal parameters are identified as a reaction temperature ranging from 85 ℃ to 90 ℃, a reaction duration of 2.0 h to 2.5 h, and a controlled zinc powder dosage of 4.0 g/L. Crucially, the auxiliary materials are introduced via the simultaneous addition of a 10 g/L copper sulfate solution and a 2 g/L antimony salt solution. These solutions are administered in 12 discrete batches at a continuous rate of 0.6 mL every 10 min. The implementation of this optimized multi-batch feeding process successfully reduces the residual cobalt concentration in the purified liquid to below 0.5 mg/L, satisfying the strict requirements for subsequent electrowinning. Furthermore, the process yields a substantial decrease in reagent usage, reducing the specific consumption of zinc powder from 70 kg/t of zinc sheet to approximately 35 kg/t of zinc sheet. To elucidate the fundamental mechanism by which these specific additives enhanced cobalt precipitation, the solid residues were analyzed using scanning electron microscopy(SEM), X-ray diffraction(XRD), and X-ray photoelectron spectroscopy(XPS). The microstructural and compositional analyses indicate that during the cementation process with zinc powder, the soluble antimony reacts with cobalt and copper to generate distinct solid-state intermetallic compounds, primarily identified as Co-Sb and Co-Cu alloy phases. The precipitation of these intermetallic phases effectively immobilizes the cobalt ions and inhibits the re-dissolution of cobalt back into the aqueous phase. Concurrently, copper and antimony co-deposited directly onto the zinc powder surface, establishing highly active Cu-Zn and Sb-Zn microcell systems. The formation of these localized microcells cause a negative shift in the local cathodic potential, which significantly lower the thermodynamic energy barrier required for cobalt precipitation and accelerate the overall electron transfer rate. Ultimately, the multi-batch solution feeding methodology prevents the formation of localized concentration gradients within the reaction system. This uniform distribution maximizes the reactive surface area and substantially improves the overall utilization efficiency of the antimony salts, enabling efficient deep decobaltation in complex hydrometallurgical solutions.