THE MINERALOGICAL CHARACTERIZATION OF TELLURIUM IN COPPER ANODES

A mineralogical study of a ''normal'' commercial copper anode and six tellurium-rich copper anodes from the CCR Refinery of the Noranda Copp er Smelting and Refining Company was carried out to identify the tellu rium carriers and their relative abundances. In all the anodes, the ma jor tellurium carrier is the Cu2Se-Cu2Te phase which occurs as a const ituent of complex inclusions at the copper grain boundaries. In tellur ium-rich anodes, the molar tellurium content of the Cu2Se-Cu2Te phase can exceed that of selenium. Although >85 pct of the tellurium occurs as the Cu2Se-Cu2Te phase, minor amounts are present in Cu-Pb-As-Bi-Sb oxide, Cu-Bi-As oxide, and Cu-Te-As oxide phases which form part of th e grain-boundary inclusions. About 1 pct of the tellurium content of s ilver-rich anodes occurs in various silver alloys, but gold tellurides were never detected. Surprising is the fact that 2 to 8 pct of the to tal tellurium content of the anodes occurs in solid solution in the co pper-metal matrix, and presumably, this form of tellurium dissolves at the anode interface during electrorefining.