Leaching Kinetics of Selenium, Tellurium and Silver from Copper Anode Slime by Sulfuric Acid Leaching in the Presence of Manganese(IV) Oxide and Graphite

Kurniawan Kurniawan,Jae-Chun Lee,Sookyung Kim,Jonghyun Kim,Rina Kim

doi:10.3390/iec2m-09233

Kurniawan Kurniawan, Jae-Chun Lee + Show 3 more

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https://doi.org/10.3390/iec2m-09233

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Abstract

Sulfuric acid leaching of copper anode slime (CAS) in the presence of manganese(IV) oxide (MnO2) and graphite was investigated for Se, Te and Ag recovery. The study reveals that the leaching of Se, Te and Ag was facilitated by the galvanic interaction with MnO2, and graphite played the role of a catalyst. The leaching process could yield 81.9% Se, 90.8% Te, and 80.7% Ag leaching efficiency when the conditions were maintained as 500 rpm, 2.0 M H2SO4, 0.8/0.8/1 MnO2/graphite/CAS, and 90 °C temperature. The kinetic study showed that Se leaching followed the surface chemical reaction at all the tested temperature range (25–90 °C) with the activation energy of 27.7 kJ/mol. Te and Ag leaching at temperature 25–50 °C followed the mixed and surface chemical reaction models, respectively, and changed to fit the diffusion and mixed control models, respectively, in the temperature range 60–90 °C with the corresponding activation energy of 17.8 and 12.2 kJ/mol.

Highlights

Copper anode slime (CAS), a byproduct of copper electrorefining process, has long been used as a secondary resource for various critical metals, such as Au, Ag, Pt, Pd, Se, Te, Cu, etc
For an instance, roasting of CAS either through oxidative or sulfation roasting results in loss of Se fraction. Another option of soda roasting is unfavorable in practice because of the subsequent acid leaching process which increases the reagent consumption for acidification/neutralization and produces low-cost byproducts
Te and Ag from copper anode slime (CAS) were recovered by sulfuric acid leaching in the presence of MnO2

Summary

Introduction

Copper anode slime (CAS), a byproduct of copper electrorefining process, has long been used as a secondary resource for various critical metals, such as Au, Ag, Pt, Pd, Se, Te, Cu, etc. Metallurgical treatments of CAS for recovering these valuable metals include the stepwise thermal-aqueous, aqueous-thermal, aqueous-aqeuous processes, consisting of roasting to recover Se and oxidative leaching to Te and Cu, prior to the recovery of precious metals [1].Despite the extensive investigation on the aforesaid processes, problematic facts remain. For an instance, roasting of CAS either through oxidative or sulfation roasting results in loss of Se fraction. Another option of soda roasting is unfavorable in practice because of the subsequent acid leaching process which increases the reagent consumption for acidification/neutralization and produces low-cost byproducts. HNO 3 was used as the oxidant for the leaching of Se from decopperized CAS, which achieved

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