Design of optimal electrolyte circulation based on the kinetic modelling of copper dissolution in silver electrorefining

Arif Aji, Joseph Hamuyuni, Jari Aromaa, Benjamin P. Wilson, Mari Lundström*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Copper is the major impurity dissolved in silver electrorefining which potentially accumulates in the electrolyte during the process and co-deposits onto the cathode surface, decreasing the product quality. The study investigated the dissolution kinetics of copper in silver electrorefining as a function of wt%Cu in the industrial electrolyte ranges of 40–100 g/dm3 [Ag+], 5–15 g/dm3 [HNO3] and 20–60 g/dm3 [Cu2+] at 25–45 °C. The results showed that Cu dissolved at a higher rate in comparison to silver and that the two kinetic models developed have good accuracy and validity. From the models, optimal electrolyte circulation parameters were simulated to avoid [Cu2+] accumulation in the electrolyte. As a conclusion, processing 1% Cu anodes at the critical [Cu2+]/[Ag+] ratio of 0.8 in the electrolyte requires an inlet of [Ag+] of 2.3–3.3 and tolerates [Cu2+] of 0.14–0.47 times that of the [Ag+] and [Cu2+] in the bulk electrolyte, respectively. Furthermore, electrolyte with higher [Ag+] provides the benefit of reduced electrolyte circulation flowrate and increased tolerance of wt%-Cu in the silver anodes.
Original languageEnglish
Article number105403
JournalHydrometallurgy
Volume196
Early online date20 Jun 2020
DOIs
Publication statusPublished - 1 Sep 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • Copper dissolution
  • Model-bassed process design
  • Silver electrorefining

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