Abstract:

Te, Au, Pt and Pd in the copper-rich solution from copper anode slime by sulfation roasting-sulfuric acid leaching treatment were reduced by Fe²⁺, and new ecological Te colloid were simultaneously formed to selectively capture the precious metals of Au, Pt and Pd. The dissolution mechanism of precious metals in copper-rich solution were analyzed based on pretreatment of copper anode slime. The φ-pH diagram of As-Fe-H₂O system were drawn by thermodynamic calculation to instruct the control of electrode potential of the copper-rich solution. The mechanism of in-situ reduction of rare and precious metals were discussed based on electrode potential of main metal ions in copper-rich solution. Under the optimal conditions of reaction temperature of 85℃, reaction time of 1.5h, stirring speed of 300r/min, and Fe²⁺ dosage of 2g/L, the precipitate efficiency of Au, Ag, Pt, Pd, Se, Te and As were 100%, 100%, 99.2%, 99.6%, 33.3%, 36.1% and 16.8%, respectively. The grades of Te, Au, Ag, Pt and Pd in the precipitated residue are 18.24%, 124g/t, 10.54%, 1010g/t and 320g/t, respectively. XRD analysis shows that the main phase of the residue is AgCl, and other components did not show obvious diffraction peaks due to amorphous or low content. The microscopic morphology of the residue is mainly fine powder and particles. SEM images of the residue shows that Ag and Cl have obviously consistent enrichment areas, As and Fe have similar enrichment areas to form AgCl and FeAsO₄ in the residue. The proposed process environmentally friendly and low cost with simplicity in operation, which had achieved efficient and comprehensive recovery of rare and precious metals in copper-rich solution.

Key words: copper anode slime, copper-rich solution, rare and precious metals, reduction, recovery, thermodynamics, potential control, captured by tellurium

摘要：

以铜阳极泥硫酸化焙烧-酸浸脱铜所得分铜液为原料，采用Fe²⁺原位还原分铜液中的Te、Au、Pt和Pd，协同生成新生态胶体状碲选择性高效捕集Au、Pt和Pd等贵金属。根据铜阳极泥的预处理工艺，分析了贵金属在分铜液中的溶解机理；通过热力学计算绘制了As-Fe-H₂O系电位-pH图，指导调控分铜液电极电位；根据分铜液中主要金属离子的电极电位，探讨了分铜液原位还原稀贵金属机理。在Fe²⁺浓度为2g/L、搅拌速度为300r/min和85℃的优化条件下反应1.5h，贵金属Au、Ag、Pt和Pd的沉淀率分别为100%、100%、99.2%和99.6%，Se、Te和As的沉淀率分别为33.3%、36.1%和16.8%，沉淀渣中Te、Au、Ag、Pt、Pd品位分别为18.24%、124g/t、10.54%、1010g/t、320g/t，XRD分析表明，沉淀渣物相组成主要为AgCl，其他成分呈非晶态或含量较低未出现明显衍射峰，微观形态主要为细微颗粒和较规则晶体状，SEM面扫描图谱显示银和氯具有明显一致的富集区域，砷与铁具有较一致的富集区域，主要形成AgCl、FeAsO₄物相赋存渣中。该工艺简单、成本低、对环境友好，实现了分铜液中稀贵金属的高效综合回收。

关键词: 铜阳极泥, 分铜液, 稀贵金属, 还原, 回收, 热力学, 电位调控, 碲捕集