Perfect 👍 — next in **periodic table order** is **Holmium (Ho, atomic number 67).**
Holmium is a **lanthanide (rare earth metal)** that occurs primarily in **monazite (Ce,La,Ho,Th)PO₄** and **bastnäsite (Ce,La,Ho)(CO₃)F**. Industrial extraction involves **acid or alkaline digestion, solvent extraction, and reduction**.
Here are the **20 most common methods of extracting Holmium**:
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# **20 Most Common Methods of Extracting Holmium**
### **A. Extraction from Rare Earth Ores**
1. **Crushing and Grinding of Monazite or Bastnäsite** – Prepares ore for chemical treatment.
2. **Acid Digestion (H₂SO₄ or HCl) of Monazite** – Dissolves holmium and other REEs.
3. **Alkaline Digestion (NaOH) of Monazite** – Converts phosphate to soluble holmium salts.
4. **Leaching of Bastnäsite with Acid or Alkali** – Produces soluble holmium compounds.
5. **Purification by Precipitation of Thorium and Other Impurities** – Removes radioactive and heavy elements.
6. **Solvent Extraction of Holmium Salts** – Organophosphorus extractants separate Ho³⁺ from other REEs.
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### **B. Separation and Concentration**
7. **Ion Exchange Separation of Holmium** – Separates Ho³⁺ from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium.
8. **Fractional Precipitation Using Oxalates or Hydroxides** – Concentrates holmium from mixed REE solutions.
9. **Conversion to Holmium Carbonate (Ho₂(CO₃)₃)** – Precursor for oxide formation.
10. **Calcination to Holmium Oxide (Ho₂O₃)** – Prepares for reduction or industrial use.
11. **Selective Solvent Extraction from Mixed REE Solutions** – Enhances separation efficiency.
12. **Chelating Agent Separation** – Laboratory or pilot-scale selective extraction.
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### **C. Reduction to Metallic Holmium**
13. **Calciothermic or Metallothermic Reduction of Ho₂O₃ → Ho** – Main industrial method.
14. **Electrolytic Reduction of Molten HoCl₃** – Produces high-purity metallic holmium.
15. **Vacuum Distillation of Metallic Holmium** – Purification for ultra-high purity Ho.
16. **Hydrogen Reduction of Holmium Halides** – Laboratory-scale method.
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### **D. Recovery from Byproducts / Secondary Sources**
17. **Recovery from Monazite Sands during Thorium Extraction** – Holmium collected as a byproduct.
18. **Recovery from Bastnäsite Refining** – Ho separated during extraction of other REEs.
19. **Recovery from Spent Rare Earth Catalysts** – Leaching + precipitation.
20. **Recovery from Recycled Electronics Containing REEs** – Hydrometallurgical extraction.
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✅ **Summary:**
* **Main industrial sources:** Monazite, bastnäsite.
* **Primary extraction steps:** Ore crushing → acid/alkaline digestion → purification → selective precipitation → reduction/electrolysis → metallic holmium.
* **Metallic holmium:** Produced via calciothermic/metallothermic reduction or molten salt electrolysis.
* **Byproduct sources:** Thorium extraction residues, bastnäsite processing, spent REE catalysts, recycled electronics.
* **Laboratory/experimental:** Ion exchange, selective solvent extraction, vacuum distillation, hydrogen reduction.
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Next in periodic order is \*\*Erbium (Er, atomic number 68).
Do you want me to continue with **20 extraction methods for Erbium**?
