砷元素对铜电解精炼阳极钝化行为的影响

Effect of Arsenic on the Passivation Behavior of Anodes in Copper Electrorefining

摘要:

杂铜阳极已成为工业电解精炼生产的必然选择，但其杂质元素引起的阳极钝化问题，严重影响工业生产和阴极铜质量。砷作为有效抑制阳极钝化的元素，其机理尚不明确。本文对浇铸含砷杂铜阳极电解过程中的阳极极化曲线、恒流氧化曲线、恒电势氧化曲线分析研究，对阳极表面进行AFM表征，对钝化膜和阳极泥进行XRD、SEM、XPS表征，探究砷元素对阳极钝化行为的影响和抑制阳极钝化的机理。结果表明：阳极中砷元素含量升高，其钝化电位和活性溶解时间明显增加，阳极表面溶解更加均匀，抑制阳极钝化的作用越加明显。钝化膜的主要成分是Cu2O，阳极泥的主要成分是As2O3和Cu3As。砷元素溶解产生的H+会降低阳极表面pH，抑制Cu2O钝化膜产生；阳极中砷含量越高，形成的阳极泥结构更加疏松，容易脱落。砷元素的钝化阈值下限为0.02 wt.%，小于该值时阳极钝化趋势增加；较高砷含量的杂铜阳极不容易钝化。

Abstract:

Mixed copper anodes have become the inevitable choice for industrial electrolytic refining, but the anode passivation issues caused by impurity elements severely impact industrial production and cathode copper quality. The mechanism by which arsenic effectively suppresses anodic passivation remains unclear. This study investigates the influence of arsenic on anodic passivation behavior and its inhibition mechanism by analyzing the anodic polarization curve, constant-current oxidation curve, and constant-potential oxidation curve during the electrolysis of cast arsenic-containing mixed copper anodes. The anodic surface is characterized using AFM, while the passivation film and anodic sludge undergo XRD, SEM, and XPS characterization. The results indicate that an increase in arsenic content within the anode leads to a significant rise in its passivation potential and active dissolution time. Dissolution at the anode surface becomes more uniform, and the inhibitory effect on anodic passivation becomes increasingly pronounced. The passivation film primarily consists of Cu?O, while the anode sludge mainly comprises As?O? and Cu?As. The H+ ions generated by arsenic dissolution lower the pH at the anode surface, inhibiting the formation of the Cu?O passivation film. Higher arsenic content in the anode results in a more porous anode sludge structure that is prone to detachment. The lower passivation threshold for arsenic is 0.02 wt.%; below this value, the anode exhibits increased passivation tendencies. Copper scrap anodes with higher arsenic content are less prone to passivation.