Perfect 👍 — next in **periodic table order** is **Cobalt (Co, atomic number 27).**
Cobalt is a **transition metal** that rarely occurs free in nature. It is primarily found in **cobaltite (CoAsS), erythrite (Co₃(AsO₄)₂·8H₂O), and as a byproduct in copper and nickel ores**. Industrial extraction involves **roasting, leaching, and reduction processes**.
Here are the **20 most common methods of extracting Cobalt**:
---
# **20 Most Common Methods of Extracting Cobalt**
### **A. Industrial / Large-Scale Extraction**
1. **Roasting of Cobalt Ores (CoAsS, CoS) → Co₃O₄** – Converts sulfides to oxides.
2. **Acid Leaching of Roasted Ores (H₂SO₄ or HCl)** – Dissolves cobalt for separation.
3. **Ammonia Leaching (NH₄OH/NH₄Cl) of Oxide Ores** – Produces soluble cobalt-ammonia complexes.
4. **Solvent Extraction from Cobalt-Containing Solutions** – Uses organophosphorus or amine extractants.
5. **Ion Exchange Purification** – Separates cobalt from nickel, copper, or iron.
6. **Precipitation as Cobalt Hydroxide (Co(OH)₂)** – Intermediate step before reduction.
---
### **B. Reduction to Metallic Cobalt**
7. **Hydrogen Reduction of CoO or Co₃O₄** – Produces metallic cobalt powder.
8. **Electrolytic Reduction of Co²⁺ Solutions** – Produces high-purity cobalt metal.
9. **Aluminothermic Reduction of Co₃O₄** – Laboratory or specialty metal production.
10. **Reduction of Cobalt Chloride (CoCl₂) with Sodium or Potassium** – Lab-scale metallothermic method.
11. **Magnesiothermic Reduction of CoO** – Experimental lab method.
12. **Reduction of Cobalt Sulfate (CoSO₄) with Hydrogen** – Lab-scale metallic cobalt production.
---
### **C. Extraction from Byproducts / Slags**
13. **Recovery from Nickel-Copper Slag** – Reclaiming cobalt from metallurgical byproducts.
14. **Recovery from Copper Refinery Electrolytes** – Cobalt present as minor contaminant in copper electrolytes.
15. **Recovery from Spent Batteries (Li-ion)** – Hydrometallurgical leaching and precipitation.
16. **Extraction from Laterite Ores** – Acid leaching followed by solvent extraction.
17. **Extraction from Recycling of Superalloys** – Specialty industrial source.
---
### **D. Specialized / Experimental Methods**
18. **Electrochemical Recovery from Mixed Metal Solutions** – High-purity cobalt production.
19. **Plasma Reduction of Cobalt Oxides** – Laboratory or research-level method.
20. **Solar-Thermal Carbothermic Reduction of CoO** – Experimental renewable energy method.
---
✅ **Summary:**
* **Main industrial method:** Roasting → acid/ammonia leaching → solvent extraction → reduction to Co metal.
* **Metallic cobalt production:** Hydrogen reduction, electrolysis, or aluminothermic reduction.
* **Byproduct sources:** Copper/nickel refinery residues, battery recycling, laterite ores.
* **Lab/experimental:** Mg, Na, plasma, or solar-thermal reductions.
---
Next in periodic order is **Nickel (Ni, atomic number 28).**
Do you want me to continue with **20 extraction methods for Nickel**?
