Purification Circuit

Trace impurities of cadmium, cobalt, copper, thallium, and antimony are removed from the solution by adding slurried zinc dust through three stages of purification. The first stage is at normal solution temperature (60ºC) to remove copper and cadmium; the second stage is heated to 78ºC to remove cobalt; the third stage is a polish stage for removing any residual of the listed impurities. All the solution is filtered between each stage through manual plate and frame filters on the first and third stages and automated pressure filters on the second stage.

Hot solution is cooled in three forced-draft atmospheric cooling towers to precipitate gypsum which is then removed by settling in a 24-m clarifier. The clear purified zinc solution is then pumped to the Electrolytic Plant.

Seen above is an external view of the Purification Circuit in which impurities are removed from zinc electrolyte.