有色金属工程（有色金属（中英文））

针对冶炼渣灰粒度细、化学组分复杂等特点，研究非氰浸出体系直接提取银技术，通过HSC、XRD衍射、激光粒度仪、ICP等手段方法，对冶炼渣灰及过程产物进行理化性能及热力学分析，明晰了硫代硫酸根与银反应形成[Ag(S_2O₃)₂]^3-络合离子的热力学机理，探明了硫代硫酸钠选择性浸出银的可行性。开展非氰体系浸出过程研究，采用硫代硫酸钠体系对冶炼渣灰进行选择性提银，查明了影响银浸出的主要制约因素有硫代硫酸盐用量、[NH₄]⁺浓度和Cu²⁺浓度等，优化了硫代硫酸钠浸出工艺，获取了选择性提银的优化条件：硫代硫酸钠用量20%、浸出液固比4∶1 mL·g^-1、[NH₄]⁺浓度2 g·L^-1、硫酸铜浓度5 g·L^-1、浸出时间1 h，在此条件下，银的平均浸出率为94.07%，基本实现了银的选择性提取。

Silver,renowned for its exceptional electrical conductivity and chemical stability,is extensively utilized in electronics,chemical engineering,medical devices,jewelry,currency and other fields. Currently,cyanide leaching dominates silver extraction due to its efficiency and low cost,yet its high toxicity poses significant environmental and operational risks. Addressing the issue,considering the characteristics of fine particle size and complex chemical composition of silver-bearing residues,this study systematically investigated a direct cyanide-free leaching process alternative for recovering silver from silver-bearing residues. Recognizing these limitations and prompted by the need for safer,greener alternatives,considering the characteristics of fine particle size and complex chemical composition of silver-bearing residues,this research focuses on developing a non-cyanide leaching system specifically designed for the direct extraction of silver from metallurgical residues. To address these challenges comprehensively and establish a viable cyanide-free pathway,the study employed a multi-faceted analytical approach utilizing advanced characterization techniques. These included thermodynamic simulations using HSC chemistry software,phase identification via X-ray diffraction(XRD) analysis,particle size distribution measurements using laser granulometry,and elemental composition determination through inductively coupled plasma(ICP) spectroscopy. These techniques were applied systematically to both the raw feed materials and intermediate products generated throughout the leaching process to gain fundamental insights into their physicochemical properties and underlying reaction mechanisms. The investigation successfully clarified the thermodynamic mechanism by which thiosulfate anions(S_2O₃^2-) react with silver ions(Ag+) to form the stable,soluble complex anion Ag(S_2O₃)₂^3-. This mechanistic understanding provided a critical theoretical foundation,conclusively demonstrating the fundamental feasibility of utilizing sodium thiosulfate(Na_2S_2O₃) as a selective lixiviant for silver extraction from complex matrices like metallurgical residues. Building upon this thermodynamic validation,the research proceeded to conduct systematic experimental investigations into the leaching process parameters within the sodium thiosulfate system. The primary goal was to achieve selective silver dissolution while minimizing the co-dissolution of other undesirable metallic components present in the metallurgical residues. The most significant factors controlling the leach kinetics and overall silver yield were determined to be:1)the concentration of sodium thiosulfate,2)the concentration of ammonia(acting as a stabilizer and pH buffer),and 3)the concentration of catalytic cupric ions(Cu²⁺). The presence of copper ions,in particular,plays a crucial catalytic role in facilitating the oxidation and dissolution of metallic silver within the thiosulfate medium. An intensive optimization process was undertaken,systematically varying these critical parameters to establish the most effective conditions for maximizing silver recovery and selectivity. Under optimal conditions(20% reagent dosage,4∶1 liquid-solid ratio,2 g · L^-1 ammonia concentration,5 g · L^-1 copper sulfate addition,20 °C leaching temperature,1 h leaching time),a remarkable 94.07% average silver leaching rate was achieved. This process enables selective silver recovery with minimized environmental impact,demonstrating significant advantages over conventional cyanide-based methods.