“GETTING REEs FROM CFA – SOME SUGGESTED SOLUTIONS” by Ashim Kumar Mukherjee
This article addresses the urgent need for India to secure Rare Earth Elements (REEs), critical to various industries including automotive and electronics, especially after China halted their export. The focus is on Coal Fly Ash (CFA)—a waste product from coal-fired power plants—as a viable secondary source of REEs.
Key Points:
1. Context and Need:
- India faces a REE shortage impacting industries.
- Traditional REE sources like monazite are insufficient or slow to process.
- Coal, especially from Meghalaya, may contain valuable REE minerals such as monazite-Ce and rutile (TiO₂).
- CFA, a by-product of Indian thermal power plants, offers an alternative REE source.
2. Presence of REEs in CFA:
- Studies by BARC and others have confirmed the presence of valuable REEs (e.g., cerium up to 218 µg/g in CFA samples).
- Outlook coefficients from different studies suggest CFA has promising REY potential (values ≥ 0.7 considered promising).
3. Methods for Recovery:
- Magnetic Separation: Isolates iron-rich, REE-bearing components.
- Sensor-Based Sorting: Uses X-ray transmission tech with machine learning, similar to airport baggage scanners.
- Ionic Leaching: Uses Ionic Liquids (IL) or Deep Eutectic Solvents (DES) for eco-friendly REE extraction. ILs are promising due to selectivity and low toxicity.
4. Current Research Project (2024–2027):
- A CSIR-NPL-led DST project aims to extract REEs from CFA using ILs.
- It includes leaching, electrodeposition, purification, and regeneration of ILs to assess scalability and environmental viability.
5. Conclusion:
- With 1,677.3 million tonnes of CFA in stock as of September 2022, India holds a vast untapped resource.
- Beyond REEs, CFA could also yield 10 million tonnes each of iron and aluminium per 100 million tonnes.
- The article urges faster R&D, government support, and industry participation to exploit CFA’s full potential as a REE source.
Glossary Highlights:
- REEs: 17 elements including lanthanides, scandium, and yttrium.
- REY: Rare Earth Elements + Yttrium.
- Outlook Coefficient: Measures the economic viability of REE extraction from a source.
- IL & DES: Green, low-toxicity solvents for metal extraction.
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GETTING REEs FROM CFA