Perfect 👍 — next in **periodic table order** is **Rhodium (Rh, atomic number 45).**
Rhodium is a **rare transition metal** that is **extremely scarce** and does **not occur free** in nature. It is primarily obtained as a **byproduct of platinum and nickel refining**, usually from **platinum group metal (PGM) ores**. Extraction involves **dissolution, selective precipitation, and reduction**.
Here are the **20 most common methods of extracting Rhodium**:
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# **20 Most Common Methods of Extracting Rhodium**
### **A. Extraction from Platinum-Group Ores**
1. **Dissolution of PGM Concentrates in Aqua Regia** – Dissolves Rh and other PGMs.
2. **Selective Precipitation as Rhodium Chloride Complexes** – Separates Rh from Pt and Pd.
3. **Oxidative Conversion to Rhodium Salts (RhCl₃·xH₂O)** – Intermediate purification step.
4. **Ion Exchange Chromatography** – Purifies Rh from mixed PGM solutions.
5. **Solvent Extraction of Rhodium Complexes** – Uses organophosphorus or amine extractants.
6. **Fractional Crystallization of Rhodium Compounds** – Separates Rh from Ir, Pd, and Pt.
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### **B. Reduction to Metallic Rhodium**
7. **Hydrogen Reduction of Rhodium Chloride or Oxide → Rh Metal** – Laboratory or small-scale industrial method.
8. **Electrolytic Deposition of Rhodium from Aqueous Solutions** – High-purity metallic Rh production.
9. **Aluminothermic Reduction of Rhodium Salts** – Lab-scale method.
10. **Magnesiothermic Reduction of Rhodium Oxide** – Experimental reduction method.
11. **Thermal Decomposition of Rhodium Compounds** – Produces metallic Rh.
12. **Carbon Reduction of Rhodium Oxides** – Specialty method for lab-scale production.
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### **C. Recovery from Byproducts / Secondary Sources**
13. **Recovery from Platinum Refinery Residues / Slags** – Acid leaching + selective precipitation.
14. **Recovery from Nickel-Copper Sulfide Ore Refining Byproducts** – Trace Rh extracted.
15. **Recovery from Spent Catalysts (Automotive or Industrial)** – Chemical dissolution + Rh precipitation.
16. **Recovery from Recycled Jewelry or Alloys Containing Rh** – Hydrometallurgical methods.
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### **D. Laboratory / Experimental Methods**
17. **Plasma Reduction of Rhodium Salts or Oxides** – High-purity experimental method.
18. **Solar-Thermal Reduction of Rhodium Oxide or Chloride** – Renewable-energy experimental method.
19. **Zone Refining of Metallic Rhodium** – Produces ultra-high purity Rh.
20. **Chemical Vapor Deposition (CVD) of Rhodium** – Produces thin films for electronics and catalysis.
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✅ **Summary:**
* **Main industrial sources:** Platinum-group metal ores and refining residues.
* **Primary extraction steps:** Dissolution → selective precipitation → complex formation → reduction → metallic Rh.
* **Metallic rhodium:** Produced via hydrogen reduction, electrolysis, or metallothermic methods.
* **Byproduct sources:** Nickel-copper ores, platinum refining residues, spent catalysts, recycled alloys.
* **Laboratory/experimental:** Plasma reduction, solar-thermal, zone refining, CVD for electronics/catalysis.
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Next in periodic order is \*\*Palladium (Pd, atomic number 46).
Do you want me to continue with **20 extraction methods for Palladium**?
