Copper processing varies depending on the type of ore being used. Oxide ores, for example, undergo a different extraction process than sulfide ores. This answer will focus on the processing of copper oxide ores.
Copper Oxide Ore Processing
The processing of copper oxide ores primarily involves hydrometallurgy, which uses water-based solutions to extract and purify the copper. This process is usually done at ordinary temperatures and consists of three main stages:
1. Heap Leaching
- What it is: This is the first step where the copper ore is piled onto a large, impermeable pad.
- Process: A leaching solution, often sulfuric acid, is sprayed over the ore heap. This solution percolates through the ore, dissolving the copper minerals.
- Outcome: The copper-containing solution, called a pregnant leach solution (PLS), is collected at the bottom of the heap.
2. Solvent Extraction
- What it is: This step separates the copper from the other dissolved elements in the PLS.
- Process: The PLS is mixed with an organic solvent that selectively extracts the copper. This mixture separates, with the copper-rich organic phase separated from the original solution.
- Outcome: The copper is transferred to a new aqueous solution, called a stripping solution. This is where the copper becomes more concentrated and ready for the final stage.
3. Electrowinning
- What it is: This is the final stage of purifying copper.
- Process: An electric current is passed through the stripping solution. Copper ions in the solution are attracted to the cathode (a metal sheet), where they are converted into pure metallic copper.
- Outcome: High-purity copper plates (also called cathodes) are produced, ready to be further processed into usable copper products.
Summary of Hydrometallurgy for Copper Oxide Ores
| Stage | Description | Goal |
|---|---|---|
| Heap Leaching | Applying a leaching solution to a pile of ore. | Dissolve copper minerals and collect a copper-containing solution (PLS). |
| Solvent Extraction | Mixing PLS with a solvent that selectively extracts the copper. | Separate copper from other elements and concentrate it in a stripping solution. |
| Electrowinning | Passing an electric current through the stripping solution. | Produce high-purity copper metal. |
This three-step method is generally how copper is processed from oxide ores. The use of aqueous solutions makes this a common method for this particular type of ore.
