Copper Extraction: Pyrometallurgy vs. Hydrometallurgy

Copper Metallurgy: Pyrometallurgy vs. Hydrometallurgy

The metallurgy of copper depends on the mineral ore. Sulfide ores utilize a pyrometallurgical route to produce anodes or cathodes, while oxide ores use a hydrometallurgical route to directly produce cathodes.

Pyrometallurgy

The cathode production process via pyrometallurgy is as follows: Mineral → Smelting (furnace) → Converters → Refining anode casting → Refining → Cathode.

Copper sulfide ore, with a low grade of 0.5%, requires concentration by flotation. The copper concentrate received in the foundry industry undergoes melting in a furnace, where copper is recovered, and sulfur and iron are removed through oxidation. The copper settles at the bottom and exits the furnace as copper matte, containing approximately 62% copper. The matte then passes through converters to increase its copper content to 99%. It proceeds to the refining furnace, where the concentration increases again, reaching 99.9%, before being cast into anodes. Finally, the anodes undergo electrorefining to produce cathodes with a purity of 99.99%.

Hydrometallurgy

Copper ore → Leach → Extract → Electrolysis → Cathode.

The ore is crushed to below 10 mm and treated in tanks. Copper oxides and secondary sulfides are leached using aqueous sulfuric acid, resulting in a copper sulfate solution with a low copper concentration. This solution, containing low concentrations of copper and impurities, is treated with a reactive organic extractant in a closed countercurrent process. This extracts the copper and produces an electrolyte with a high percentage of copper and free of impurities. The copper-rich solution then undergoes electrolysis, where an electric current causes the copper ions to deposit on cathodes.

Electrometallurgy

Electrometallurgy is a newer process where electric current is used as a reductant to obtain very pure metals from oxides. It is used to purify metals and alloys, similar to pyrometallurgy but without fuel. It can be:

• Igneous
• Electrolysis in aqueous solutions