Control of Acid Mist Formation in the Electrowinning of Copper
The formation of acid mist in the electrowinning of copper can result in a health hazard if the concentrations of the acid mist is too high. A study was carried out in a model electrowinning bath where the gas generation in an electrowinning bath was simulated by controlled gas injection. The breakup of the bubbles at the free surface controlled the mechanism for acid mist formation. The results showed that the bubble size and concentration played an important part in determining the droplet size and density that formed the acid mist. The amount of acid mist formed for different bubble concentration showed that the acid mist concentration above a model of the electrowinning bath decreases exponentially with distance from the bath surface. However, fine bubbles resulted in fine acid mist gives rise to droplets that can be carried away by the gas generated. The study identified means of reducing the acid mist concentration without the need to install complex gas cleaning and isolation equipment.