Dissolution of copper and selenium from copper anode slimes

In this study, the recovery process of copper and selenium from copper anode slimes, supplied from Sarkuysan Co. in Turkey, has been investigated by employing hydrometallurgical methods under different conditions and parameters. The applied process is composed of three major stages: Characterization of anode slime, decopperization in H₂SO₄ medium, dissolving selenium in NaOH solution from decopperized anode slimes. The phase composition and chemical analysis of anode slime were determined with X-ray diffraction (XRD) and atomic absorption spectrometry (AAS) methods, respectively. After characterization step, the decopperization of anode slime was performed by utilizing the dissolution technique in H₂SO₄ medium. The effects of oxygen flow rate and process temperature on the stage of decop-perization were studied. 93.8 % Cu recovery was achieved at a reaction temperature of 80 °C, a flow rate of 2 L/min. oxygen, a stirring speed of 800 rpm, a solid-to-liquid ratio of 1:5, the concentration of 2 M H ₂SO₄ and the reaction duration of 2 hours. Cu ₂Se was detected with the X-ray diffraction technique as a remaining phase of copper in the anode slime after decopperization process. Subsequently, decopperized anode slimes were treated by NaOH solution in order to dissolve selenium. The influences of NaOH concentration, reaction temperature and amounts of KMnO₄ additions on the dissolution of selenium were examined. The maximum recovery of 86.8 % selenium was accomplished in 4 M NaOH solution, at reaction temperature of 90 °C, the flow rate of 2 L/min oxygen, a stirring speed of 800 rpm, a solid-to-liquid ratio of 1:10 and in 3 hours of treatment.