A MINERALOGICAL OVERVIEW OF THE BEHAVIOR OF NICKEL DURING COPPER ELECTROREFINING

Nickel-bearing copper anodes and anode slimes were studied using a variety of mineralogical and chemical techniques. In anodes containing <;0.3 pct Ni, the nickel occurs only in solid solution in the copper matrix. This nickel dissolves simultaneously with the copper during electrorefining, but a small amount reprecipitates as copper-nickel sulfate or a complex Ni-bearing Cu-Ag-As-Se-S oxidate phase in the anode slimes. In anodes containing >0.3 pct Ni, NiO crystals also form. The presence of the Cu-Ni-Sb oxide, kupferglimmer, in the anode depends on its antimony content. Kupferglimmer is prevalent in nickel-rich anodes with high Sb contents (>200 ppm) but is not found in similar anodes with Sb contents <200 ppm. Various Cu-Ni and Ca-Cu-Ni silicate inclusions are present. Depending on the iron content of the anode, Fe-bearing NiO, NiFe2O4, and other Ni-bearing iron oxide phases also may be present. All of the oxidate nickel phases remain largely undissolved during electrorefining and concentrate in the anode slimes. © 1990 The Minerals, Metals & Material Society.