Perfect 👍 — next in **periodic table order** is **Indium (In, atomic number 49).**
Indium is a **post-transition metal** that does **not occur free** in nature. It is primarily obtained as a **byproduct of zinc, lead, and tin ore processing**, especially from **sphalerite (ZnS)**. Extraction involves **leaching, precipitation, and reduction**.
Here are the **20 most common methods of extracting Indium**:
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# **20 Most Common Methods of Extracting Indium**
### **A. Extraction from Zinc and Lead Ores**
1. **Leaching of Sphalerite (ZnS) Flotation Concentrates with H₂SO₄** – Dissolves indium as In³⁺.
2. **Acid Leaching of Indium-Rich Residues from Lead Refining** – Converts indium to soluble salts.
3. **Solvent Extraction of Indium from Sulfate Solutions** – Uses organophosphorus extractants.
4. **Ion Exchange Purification of Indium** – Removes impurities from leach solutions.
5. **Precipitation as Indium Hydroxide (In(OH)₃)** – Intermediate purification step.
6. **Conversion of In(OH)₃ → In₂O₃ by Calcination** – Produces indium oxide for reduction.
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### **B. Reduction to Metallic Indium**
7. **Electrolytic Reduction of Indium Sulfate or Chloride Solutions** – Produces high-purity indium cathodes.
8. **Hydrogen Reduction of Indium Oxide → In + H₂O** – Lab or small-scale industrial method.
9. **Aluminothermic Reduction of In₂O₃ → In + Al₂O₃** – Laboratory or specialty industrial method.
10. **Magnesiothermic Reduction of In₂O₃ → In + MgO** – Experimental or lab-scale method.
11. **Carbothermic Reduction of Indium Compounds** – Laboratory-scale method.
12. **Vacuum Distillation of Metallic Indium** – Purification of indium.
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### **C. Recovery from Byproducts / Secondary Sources**
13. **Recovery from Zinc Refinery Residues / Flue Dusts** – Hydrometallurgical extraction.
14. **Recovery from Lead Refinery Residues** – Acid leaching and solvent extraction.
15. **Recovery from Tin Refinery Byproducts** – Minor indium extraction.
16. **Recovery from Recycled Electronics (LCDs, LEDs)** – Indium as indium tin oxide (ITO).
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### **D. Laboratory / Experimental Methods**
17. **Plasma Reduction of Indium Oxide or Chloride** – High-purity experimental method.
18. **Solar-Thermal Reduction of Indium Oxide or Halides** – Experimental renewable energy method.
19. **Zone Refining of Metallic Indium** – Produces ultra-high purity indium.
20. **Electroless Deposition of Indium from Salts** – Produces thin metallic coatings.
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✅ **Summary:**
* **Main industrial sources:** Sphalerite (ZnS) ores, zinc, lead, and tin refining residues.
* **Primary extraction steps:** Ore/residue leaching → purification → In(OH)₃ → In₂O₃ → reduction → metallic indium.
* **Metallic indium:** Produced via electrolysis, hydrogen, or metallothermic reduction.
* **Byproduct sources:** Refinery residues, electronics (ITO layers).
* **Laboratory/experimental:** Plasma, solar-thermal, zone refining, electroless deposition.
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Next in periodic order is \*\*Tin (Sn, atomic number 50).
Do you want me to continue with **20 extraction methods for Tin**?
