Browsing by Author "Aji, Arif"

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  • Design of optimal electrolyte circulation based on the kinetic modelling of copper dissolution in silver electrorefining
    (2020-09-01) Aji, Arif; Hamuyuni, Joseph; Aromaa, Jari; Wilson, Benjamin P.; Lundström, Mari
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    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.