Copper extraction and refining are key processes for obtaining high-purity copper from sulfide ores. The combination of pyro-refining and electrolytic refining is at the core of the modern copper industry. This process not only produces extremely pure electrolytic copper but also efficiently recovers precious metals and rare elements, offering both economic and environmental benefits.

First, the product of the initial pyrometallurgical treatment, blister copper, requires further purification. Pyrometallurgical refining plays a crucial role in this stage: After the blister copper is melted, air is introduced to oxidize any remaining impurities, such as iron, zinc, and nickel, forming a scum that can be removed. Subsequently, reducing gases, such as natural gas, are injected into the melt to remove dissolved oxygen from the molten copper before it is cast into anode plates. At this point, the copper's purity reaches approximately 99.5%, but it still contains traces of impurities and valuable precious metals.

Next comes electrolytic refining, which aims to purify the copper to a higher grade. Anode plates are placed in an electrolytic cell containing a solution of copper sulfate and sulfuric acid, with a thin, high-purity copper sheet serving as the cathode. Under the influence of direct current, the anode undergoes electrochemical dissolution, and the copper enters the electrolyte in ionic form (Cu²⁺):

Cu(anode) → Cu²++2e−

At the same time, a reduction reaction occurs at the cathode, where copper ions gain electrons and are deposited as solid copper:

Cu₂++2e−→Cu(cathode)Cu₂++2e−→Cu(cathode)

Simultaneously, a reduction reaction occurs at the cathode, where copper ions gain electrons and are subsequently deposited as solid copper.

This process achieves the directional migration of copper from the anode to the cathode, ultimately yielding cathode copper (also known as electrolytic copper) with a purity of up to 99.99%, suitable for high-precision industrial applications such as electronics and power generation.

Another key advantage of electrolytic refining is the recovery of by-products. Precious metals such as gold and silver, as well as rare metals like selenium and tellurium, are insoluble in the electrolyte and therefore precipitate as "anode mud" at the bottom of the electrolytic cell. This anode mud becomes a crucial raw material for extracting these valuable elements, significantly improving the economic efficiency of the overall process.