The sizing of oxygen bubbles in copper electrowinning

Oxygen bubbles are formed on the anode in the copper electrowinning process. Burst of the bubbles produces acid mist in the tankhouse. While it is well acknowledged that the amount of acid mist is related to the size of the bubble, no systematic measurements have been made to quantify bubble size and its relationship with materials and process variables. This paper presents results of bubble size measurement under different operating conditions. For each of the operating conditions tested, bubbles were detected in a wide size distribution ranging from 20 μm to more than 400 μm in diameter. Statistical analyses on the measurement results showed that addition of FC-1100, a surfactant widely used in copper electrowinning to suppress acid mist, and solution temperature were the two most influential test parameters on the bubble size followed by the age of the anode. In contrast, current density and solution acidity had negligible effect.

► Diameter of the copper electrowinning bubbles ranged from 20 µm to more than 180 µm regardless of the operating conditions.
► FC-1100 and solution temperature had the most significant effect on the average size and size distribution of bubbles.
► Anode age affected the average size and size distribution of bubbles by influencing the solid-liquid-gas contact angle.
► Electrical current density and solution acidity had negligible effect on bubble sizes.