Metals (Jul 2024)

Impact of 5-Amino-1H Tetrazole on Reducing Silver in Copper Cathodes during Electrorefining with High Silver Content Anode Plates

  • Chen Chen,
  • Chu Cheng,
  • Mengxin Wang,
  • Haitao Liu,
  • Xiaoheng Li,
  • Kexing Song

DOI
https://doi.org/10.3390/met14070799
Journal volume & issue
Vol. 14, no. 7
p. 799

Abstract

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As the grade of the copper concentrate decreases and its composition becomes increasingly complex, the silver content in anode plates cast after fire refining increases, leading to a higher silver content in the copper cathode during electrorefining and a substantial loss of precious metals. This study investigates the impact of 5-amino-1H tetrazole (5-AT) on reducing silver in copper cathodes during electrorefining with high silver content anode plates. 5-AT forms an “adsorption layer” on the anode surface, reacting with Ag+ released by the anode to form a precipitate and prevent Ag+ from entering the electrolyte. This process agglomerates fine Ag-Se compounds and AgCl particles, creating larger anode slime particles that settle quickly, thus inhibiting fine silver-containing particles from adhering to the cathode. Furthermore, 5-AT adsorbs on the cathode, binding with Cu+ and promoting the Cu2+ electrodeposition process while inhibiting Ag+ electrodeposition. This facilitates uniform copper cathode grain growth and reduces inclusions in the copper cathode. The grain size of the copper cathode initially decreases and then increases as the concentration of 5-AT increases. At an optimal 5-AT concentration of 15 mg/L, the Ag content in the copper cathode decreased from 6.9 ppm to 4.7 ppm, indicating the potential efficacy of 5-AT in improving the quality of electrorefined copper.

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