SX-EW technology involves leaching (the process of dissolving useful ingredients with a solution) in atmospheric conditions of copper ore heaps by means of diluted sulphuric acid. Folowing leaching, the pregnant leaching solution is transported via a drainage system to the next stage. In an SX-EW reactor, the first process to take place is solvent extraction, which involves setting and simultaneous purification of the post-leaching solution. Later, the purified solution undergoes copper electrolysis, which results in cathode copper that meets quality and quantity criteria enabling its sale.
Sulphuric acid used as the leaching agent is a by-product of pyrometallurgical copper production at KGHM. Initially it was utilised or sold. With the SX-EW method in place sulphuric acid is curetly used by all KGHM's facilities in the world.
KGHM applies this technology at several of its facilities:
- Sierra Gorda in Chile. Thanks to the SX/EW processing of oxide ore, around 50 tonnes of copper cathodes have been produced.
- Franke in Chile. Above 20,000 tonnes of electrolytic copper is produced annually by means of the SX/EW method.
- Carlota in the USA. Around 4,000 tonnes of electrolytic copper is produced in Carlota annually. Although this facility is in the closure phase, electrolytic copper obtained by means of SX/EW method will continue to be produced for the next several years.