Great — now we’re on **Thorium (Th, atomic number 90).**
Thorium is a **naturally radioactive actinide**, discovered in 1828 by Jöns Jacob Berzelius. It’s about **3–4 times more abundant than uranium** in Earth’s crust and occurs mainly in **monazite sands**. Thorium is being researched as a **nuclear fuel** (in the thorium fuel cycle), and it also has historical uses in gas mantles and alloys.
Here are the **20 most common methods of extracting Thorium**:
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# **20 Most Common Methods of Extracting Thorium**
### **A. Ore Mining & Beneficiation**
1. **Mining Monazite Sands** – The main commercial source of thorium.
2. **Processing Thorite (ThSiO₄)** – A secondary ore mineral of thorium.
3. **Recovery from Uraninite/Pitchblende** – Minor thorium byproduct.
4. **Extraction from Bastnäsite Rare-Earth Ore** – Contains traces of thorium.
5. **Placer Mining of Beach Sands** – Concentrates monazite, hence thorium.
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### **B. Ore Processing & Concentration**
6. **Gravity Separation of Monazite** – Heavy mineral separation from sand.
7. **Magnetic Separation** – Distinguishes monazite from ilmenite and rutile.
8. **Electrostatic Separation** – Enhances monazite concentration.
9. **Flotation Techniques** – Further separation of thorium minerals.
10. **Acid Digestion of Monazite (Sulfuric Acid or Hydrochloric Acid)** – Dissolves thorium for chemical processing.
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### **C. Thorium Chemical Recovery**
11. **Precipitation as Thorium Hydroxide (Th(OH)₄)** – Classic first separation.
12. **Precipitation as Thorium Oxalate (Th(C₂O₄)₂)** – Yields high-purity thorium.
13. **Precipitation as Thorium Fluoride (ThF₄)** – Intermediate for metal production.
14. **Ion Exchange Separation from Rare Earth Elements** – Exploits Th⁴⁺ charge difference.
15. **Solvent Extraction (e.g., Tributyl Phosphate, TBP)** – Efficient in large-scale thorium separation.
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### **D. Metallurgical Production**
16. **Reduction of Thorium Fluoride with Calcium** – Produces metallic thorium.
17. **Reduction of Thorium Oxide with Magnesium or Calcium** – Alternative metal extraction.
18. **Electrolysis of Thorium Chloride (ThCl₄) in Molten Salt** – Direct metal recovery.
19. **Vacuum Distillation / Zone Refining** – Further purification of metallic thorium.
20. **Hydrometallurgical Recycling from Industrial Waste** – Recovery from legacy thorium-bearing materials (e.g., gas mantles, alloys).
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✅ **Summary:**
* Thorium is mainly extracted from **monazite sands**.
* Processing involves **mechanical concentration (gravity, magnetic, electrostatic separation)**, then **acid leaching**.
* Thorium is recovered via **precipitation (hydroxide, oxalate, fluoride)** and refined by **solvent extraction and ion exchange**.
* Metallic thorium is produced by **reduction or molten-salt electrolysis**.
* Its main future importance is in the **thorium nuclear fuel cycle**.
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Next up after thorium is **Protactinium (Pa, atomic number 91).**
Would you like me to continue with the **20 most common methods of extracting Protactinium**?
