Perfect 👍 — next in **periodic table order** is **Rubidium (Rb, atomic number 37).**
Rubidium is an **alkali metal** that does **not occur free** in nature. It is primarily obtained from **lepidolite, pollucite, and carnallite**, usually as a byproduct of **potassium and cesium extraction**. Rubidium is highly reactive, so its extraction requires **specialized chemical reduction** techniques.
Here are the **20 most common methods of extracting Rubidium**:
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# **20 Most Common Methods of Extracting Rubidium**
### **A. Extraction from Lepidolite and Other Minerals**
1. **Acid Leaching of Lepidolite (HF/H₂SO₄)** – Dissolves rubidium along with potassium and lithium.
2. **Alkaline Fusion (NaOH or KOH) of Lepidolite** – Converts silicate minerals to soluble rubidium compounds.
3. **Fractional Crystallization of Rubidium Salts** – Separates RbCl from KCl and CsCl.
4. **Ion Exchange Separation of Rubidium from Potassium** – Uses selective resins.
5. **Solvent Extraction from Leach Solutions** – Organic extractants separate rubidium.
6. **Precipitation as Rubidium Carbonate (Rb₂CO₃)** – Intermediate step.
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### **B. Reduction to Metallic Rubidium**
7. **Aluminothermic Reduction of Rb₂CO₃ / RbCl** – Produces metallic rubidium.
8. **Calciothermic Reduction (Ca + RbCl → Rb + CaCl₂)** – Industrial or lab method.
9. **Sodium Reduction of RbCl** – Lab-scale metallothermic reduction.
10. **Electrolytic Reduction of Rb Compounds (Molten Salts)** – Produces high-purity rubidium metal.
11. **Reduction of RbOH with Lithium or Sodium** – Laboratory method.
12. **Vacuum Distillation of Rubidium Metal** – Purification step after reduction.
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### **C. Extraction from Byproducts**
13. **Recovery from Potash Mining Brines (KCl-rich)** – Rubidium is present in minor quantities.
14. **Recovery from Cesium Extraction Residues** – Separation from CsCl and KCl mixtures.
15. **Recovery from Lithium-Containing Mineral Processing** – Rubidium traces in spodumene or lepidolite residues.
16. **Recovery from Salt Lake Brines** – Hydrometallurgical extraction.
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### **D. Laboratory / Experimental Methods**
17. **Reduction of Rubidium Chloride with Magnesium** – Lab metallothermic reduction.
18. **Magnesiothermic Reduction of Rubidium Compounds** – Experimental lab method.
19. **Plasma Reduction of Rubidium Salts** – Research-level metallic rubidium production.
20. **Solar-Thermal Reduction of Rubidium Compounds** – Experimental renewable energy method.
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✅ **Summary:**
* **Main industrial sources:** Lepidolite, pollucite, carnallite, potash brines.
* **Primary extraction steps:** Leaching → fractional crystallization/ion exchange → precipitation → reduction to metallic rubidium.
* **Metallic rubidium:** Produced via aluminothermic, calciothermic, sodium, or electrolytic reduction.
* **Laboratory/experimental:** Mg/Na reductions, plasma, solar-thermal methods.
* **Byproduct sources:** Cesium, potassium, lithium processing residues.
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Next in periodic order is \*\*Strontium (Sr, atomic number 38).
Do you want me to continue with **20 extraction methods for Strontium**?
