Mineralogical Characterization of Anode Slimes—II. Raw Anode Slimes from Inco's Copper Cliff Copper Refinery

Abstract

The raw anode slimes produced in Inco's Copper Cliff Copper Refinery have been characterized by a variety of mineralogical techniques. The anode slimes consist principally of euhedral NiO crystals, Ag-Cu selenides, PbSO4 and silicates as well as trace amounts of Pb-Cu-Bi oxide, Ag2Te and BaSO4. The slimes particles generally are agglomerated by a matrix phase of Cu-Ni sulphates which often seems to be stabilized by silica gel. Copper oxide, a major phase in the original anodes, is not present because of its rapid dissolution in the electrolyte. Although some of the anode slimes species, such as the NiO crystals, simply seem to have passed unaltered from the copper anode to the anode slimes layer, other species have undergone significant reaction in the slimes layer. The selenides react rapidly with silver ion liberated from the copper matrix to form silver-bearing copper selenide and, subsequently, AgCuSe. This reaction progresses from the outer surface of the Cu2Se inwards, and a range of Ag-Cu selenide compositions can be present even in a single grain. Tellurium, which occurs principally in solid solution in the original copper selenide, sometimes is precipitated as Ag2 Te during the silver enrichment reaction. Numerous silicate particles are present. Many of these are simply occluded filter aid, but the morphology and composition of some of the other silicate phases indicate an origin in the cast anode itself.