Acidic Mecer process
The First stage
Used etchant is passed through two counter current stages
of extraction whereby the copper concentration drops
from approx. 220 g/l to 200 g/l allowing for reuse as main
etchant make up chemistry for the etching process.
The Second stage
Used rinse water is passed through the third stage of extraction whereby the copper concentration drops from approx. 8 g/l to < 0.1 g/l. In order to accomplish this some caustic soda is fed to the extraction stage.
The Third stage
Acid electrolyte from the electrowinning cell is passed through the fourth and fifth stages for reextraction increasing its copper concentration before being returned for continuous copper plating in the electrowinning cell.
Electrowinning unit
The copper loaded acid (electrolyte) travels from the forth and fifth extraction stages to the electrowinning cell where the copper is plated onto copper starter sheets. When a cathode's weight reaches ~125 kg it is removed from the system and sold as electrolytic grade copper.
The process of plating the copper regenerates the acid in the electrolyte so that it is ready to be used again to strip the copper from the organic.