Sequential removal of selenium and tellurium from copper anode slime with high nickel content

A process using soda roasting alkaline leaching acid leaching to remove selenium, tellurium and copper sequentially from the copper anode slime with high content of Ni was tested. The mechanism of this process was outlined based on thermodynamic analysis and the change in the XRD patterns of different intermediate products. During soda roasting, copper which occurs as Cu4SeTe in the slime was oxidized to CuO and Cu3TeO6, while selenium and tellurium were oxidized to Ag2SeO4 and Cu3TeO6, respectively. Ag2SeO4 in the calcine is easily leached in the subsequent alkaline leaching, but CuTeO3 resulted from the decomposition of Cu3TeO6 remains inactive in this process through which selenium is leached out in preference to tellurium. The CuTeO3 and CuO in the alkaline leaching residue can be leached in the following sulfuric acid leaching process. More than 97% of selenium was leached with little tellurium leached under the optimal condition. Then, more than 96% of copper and almost all the tellurium were leached out in the following acid leaching process.