Abstract: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.

Key words: copper anode slime; tellurium; selenium; soda roasting; alkaline leaching; acid leaching