Abstract: The Kaldo furnace smelting technology is a typical process for the comprehensive treatment of copper anode slimes. However, the reduction sequence of key components and the phase evolution mechanisms remain unclear. In this study, simulations are conducted to analyze the slag system and reduction thermodynamics. The phase evolution during the reduction smelting of decoppered anode slimes for the collection of precious and rare metals is investigated through microscopic characterization of the slag and noble lead samples.The results indicate that the reduction smelting of decoppered anode slimes primarily forms a PbO-Na2O-SiO2 ternary slag system containing PbSiO3 and Na2Si2O5 phases. The reduction sequence of elements is determined as Ag>Se>Te>Bi>Pb. The main phase evolution pathway of PbSO4 follows the sequence PbSO4→PbO?PbSO4→PbS→Pb. The noble lead phases consist of PbSe, BiSe, and AgTe, with no diffraction peaks corresponding to elemental single phases observed. SEM analysis reveals that Pb and Se share similar distribution regions, while Ag and Bi exhibit complementary distribution patterns. Te is uniformly distributed, whereas Ag, Bi, and Pb show concentrated distribution zones with phenomena of segregation and contrast differences. XPS results show that Pb, Ag, Bi and Te in precious lead have zero valence and positive valence, and the proportion of 0 valence is 64%, 88%, 52%, and 47%, respectively. In contrast, Se exists in 38% zero-valence state and 62% negative valence state (Se2-). Due to the uneven distribution of metal particles, the unaggregated metal particles Pb, Bi and Se mainly form PbSe and BiSe intermetallic compounds, and Ag and Te form AgTe. Combined with XRD and SEM characterization, it is shown that the smelting reduction process of copper anode slime mainly forms stable intermetallic compounds to realize the capture of rare and precious metals.

Key words: copper anode slime, Kaldo furnace, reduction smelting, rare and precious metals, phase evolution

摘要： 卡尔多炉熔炼技术是综合处理铜阳极泥的典型工艺，但目前对其关键组分的还原顺序及物相变化规律仍缺乏明确认知。本工作通过熔炼渣型模拟计算、还原过程热力学分析，结合熔渣与贵铅的微观表征，系统研究了脱铜阳极泥还原熔炼过程中稀贵金属捕集的物相演变规律。结果表明，脱铜阳极泥还原熔炼过程中，主要形成以PbSiO3和Na2Si2O5物相的PbO-Na2O-SiO2三元渣系；各元素的还原优先级顺序为Ag>Se>Te>Bi>Pb，主要成分PbSO4的物相演变历程为PbSO4→PbO?PbSO4→PbS→Pb；贵铅物相为PbSe, BiSe和AgTe，未出现元素单质的衍射峰；形貌分析显示，Pb和Se的分布区域高度重合，Ag和Bi呈互补分布特征，Te在整体区域内均匀分布，且Ag, Bi, Pb均有集中分布区域，存在偏聚现象及衬度差异；贵铅中Pb, Ag, Bi和Te元素均存在0价和正价，0价占比分别为64%, 88%, 52%和47%，Se以0价(38%)和负价(62%，主要为Se2-)存在。结合XRD和SEM表征结果可知，铜阳极泥在还原熔炼过程中，主要通过形成稳定的金属间化合物实现稀贵金属的捕集。

关键词: 铜阳极泥, 卡尔多炉, 还原熔炼, 稀贵金属, 物相演变