Copper cathode contamination by nickel in copper electrorefining

Mika Sahlman, Jari Aromaa, Mari Lundström*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Nickel behavior has a significant role in the electrorefining of copper, and although it has been extensively studied from the anode and electrolyte point of view over the past decades, studies on nickel contamination at the cathode are limited. In the current paper, three possible contamination mechanisms—particle entrapment, electrolyte inclusions and co-electrodeposition— were investigated. Copper electrorefining (Cu-ER) was conducted at the laboratory scale, and the cathodes were analyzed by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) and flame atomic absorption spectroscopy (AAS). Particle entrapment was studied by adding NiO and Fe2O3 to the system to simulate nickel anode slime, and the experiments were replicated with industrial anode slime material. The possibility of electrolyte entrapment due to nodulation was explored through the addition of graphite to produce nodules on the cathode. Co-electrodeposition was analyzed by experiments that utilized a Hull cell. The results indicate that particle entrapment can occur at the cathode and is a major source of the nickel contamination in Cu-ER, whereas nickel compounds were not shown to promote nodulation. Inclusions of bulk electrolytes within the surface matrix were observed, proving that electrolyte entrapment is possible. As co-electrodeposition of Ni in Cu-ER is thermodynamically unlikely, these experimental results also verify that it does not occur to any significant extent.

Original languageEnglish
Article number1758
Number of pages16
JournalMetals
Volume11
Issue number11
DOIs
Publication statusPublished - 2 Nov 2021
MoE publication typeA1 Journal article-refereed

Keywords

  • Cathode contamination
  • Copper
  • Electrolyte inclusion
  • Electrorefining
  • Nickel
  • Nickel electrodeposition
  • Particle entrapment

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