Leach Mining

This demonstration models the process of leach mining used to extract metals such as copper from low-grade ores. Sulfuric acid acts as the leaching solution, dissolving the mineral from crushed rock, while an iron nail placed in the recovered solution shows metal displacement and recovery.

1. Place a small amount of copper carbonate (the model mineral) into a large beaker.
2. Fill the beaker with fine crushed rock to a few centimeters below the rim.
3. Prepare an “injection well” by inserting a pencil into a 10 cm plastic tube, drilling a hole down into the rock, then removing the pencil.
4. Set up a filter funnel in a retort stand above the injection well, and connect the funnel outlet to the plastic tube. Ensure the lower end of the tube is about 0.5 cm from the beaker bottom.
5. Slowly pour about 100 mL of 0.1M sulfuric acid into the funnel. Allow it to percolate through the crushed rock for about 2 minutes.
6. Prepare a “recovery well” by drilling another hole using the second plastic tube and pencil, about 0.5 cm from the beaker bottom on the opposite side. Remove the pencil.
7. Attach a syringe to a thin plastic tube and insert it into the recovery well.
8. Pull the syringe plunger gently to extract the leachate, and collect liquid in a test tube.
9. Add an iron nail to the test tube of recovered liquid and observe changes over several minutes.

• None available

• Try using different acid concentrations to compare extraction rates.
• Substitute copper carbonate with another carbonate mineral such as malachite or azurite.
• Use different metals (e.g., zinc, iron) for the recovery step to compare displacement reactions.
• Repeat the process using vinegar as a safer weak acid alternative for younger students.

• Wear safety glasses and gloves at all times.
• Sulfuric acid is corrosive, handle with care and rinse spills immediately with water.
• Do not inhale fumes or touch acid-soaked materials.
• Dispose of copper-containing waste as directed by your instructor or local regulations.

• What part of the setup represents the ore body, leach solution, injection well, and recovery well?
• How does this model demonstrate the process of leach mining in real-world operations?
• What chemical reaction occurs when sulfuric acid reacts with copper carbonate? (CuCO₃ + H₂SO₄ → CuSO₄ + H₂O + CO₂)
• What happened when the iron nail was placed in the blue copper sulfate solution? (Copper metal was displaced and deposited on the nail.)
• How could the copper recovered from the leach solution be purified in an actual mining operation?