Tellurium Recycling

1. Key Sources of Tellurium

• Photovoltaic (PV) Waste:
  Over 90% of global tellurium is used in cadmium telluride (CdTe) thin-film solar panels. As these panels reach their 25–30-year lifespan, recycling becomes essential. For example, 1 GW of CdTe panels contains ~150 tons of tellurium, and by 2030, 500,000 tons of end-of-life PV waste are projected globally .
• Metallurgical Byproducts:
  • Copper Anode Slimes: 90% of primary tellurium production comes from copper refining residues, where tellurium accumulates at 2–10% concentrations .
  • Lead-Zinc Smelting Dust: Tellurium-rich dust from lead and zinc smelting processes is another significant source .
• Electronic Waste:
  Discarded semiconductors, thermoelectric devices (e.g., Bi₂Te₃-based coolers), and industrial catalysts contain recoverable tellurium .

2. Recycling Processes

A. Industrial-Scale Techniques

1. Hydrometallurgical Methods:
   • Acid/Alkali Leaching:
     • Acid Leaching: Sulfuric acid (H₂SO₄) or hydrochloric acid (HCl) dissolves tellurium from CdTe panels or anode slimes. For example, CdTe is leached using H₂SO₄-H₂O₂, achieving 90% tellurium extraction .
     • Alkali Leaching: Sodium hydroxide (NaOH) is used to dissolve tellurium oxides, followed by precipitation with sulfur dioxide (SO₂) .
   • Solvent Extraction:
     Organic solvents like tri-n-octylamine (TOA) selectively separate tellurium from leach solutions, improving purity to 99.99% .
2. Pyrometallurgical Methods:
   • Vacuum Distillation: High-temperature processing (800–1,000°C) separates tellurium from heavy metals like lead and copper in anode slimes .
   • Smelting with Reductants: Carbon or hydrogen reduces tellurium oxides to metallic tellurium, often combined with slagging agents to remove impurities .
3. Emerging Technologies:
   • Supercritical Fluid Extraction:
     Using supercritical CO₂ (SC-CO₂) with chelating agents like TBP-HNO₃, tellurium dissolution rates increase 20-fold, achieving >98% recovery with minimal wastewater .
   • Electrochemical Refining:
     Electrolysis of tellurium solutions (e.g., TeO₂ in NaOH) produces 99.999% pure tellurium, used in semiconductor applications .

B. Case Studies

• Silver Group (China):
  Developed a 50-ton/year 高纯碲 (99.99%) production line from copper anode slimes, achieving 85% tellurium recovery through hydrometallurgical purification .
• Shaoguan Yuntian Metal (China):
  Uses a four-stage process (crushing-leaching-precipitation-electrowinning) to recover 78–82% of tellurium from CdTe panels, with cadmium 固化率 >99.5% .

3. Market and Economic Viability

• Global Demand:
  Tellurium consumption is dominated by PV (40%), followed by thermoelectrics (30%) and metallurgy (15%) . The market is projected to grow at 6–8% annually, driven by renewable energy policies and 5G/semiconductor expansion .
• Price Trends:
  • 4N (99.99%) Tellurium: ~¥740,000/ton ($103,000/ton) in 2025 .
  • High-Purity (6N) Tellurium: >¥2,000,000/ton ($280,000/ton) for semiconductor-grade applications .
• Cost Structure:
  • Processing Costs: $4,500–$12,500/ton using advanced technologies (e.g., SC-CO₂), compared to $12,000/ton for traditional hydrometallurgy .
  • Revenue Streams: Sales of purified tellurium, byproduct recovery (e.g., cadmium, silver), and government subsidies for resource efficiency .

4. Environmental and Policy Drivers

• Circular Economy Benefits:
  • Resource Conservation: Recycling reduces reliance on primary mining, which causes habitat destruction and heavy metal pollution.
  • Emission Reduction: For example, SC-CO₂ technology cuts energy use by 60% and wastewater by 90% compared to conventional methods .
• Regulatory Support:
  • China: Offers VAT refunds (50%) and income tax incentives for resource recycling under the Circular Economy Promotion Law .
  • EU: Mandates 85% PV panel recycling by 2030 under the New Battery Regulation.
  • U.S.: The Inflation Reduction Act provides tax credits for domestic rare metal recycling .

5. Technical Challenges

1. Complex Feedstock:
   • Impurities: Tellurium often coexists with selenium, lead, and cadmium, requiring advanced separation techniques .
   • Heterogeneous Waste Streams: E-waste and PV panels vary in composition, complicating automated sorting .
2. Energy and Chemical Intensity:
   Traditional hydrometallurgical processes consume large amounts of acids (e.g., 8 tons H₂SO₄/ton Te) and energy .
3. Scalability:
   While lab-scale recovery rates exceed 98%, industrial-scale operations often achieve 70–85% due to process inefficiencies .

6. Industry Players and Partnerships

• Major Producers:
  • China: Jiangxi Copper, Baiyin Group, and Chinalco dominate primary and recycled tellurium production .
  • International: First Solar (U.S.) recycles its own PV waste, while Umicore (Belgium) focuses on high-purity tellurium for semiconductors .
• R&D Collaborations:
  Universities and companies are developing AI-driven sorting systems and bioleaching technologies to enhance efficiency .

7. Future Outlook

• Technology Integration:
  • AI and Robotics: Automated sorting of e-waste and real-time process optimization via machine learning .
  • Green Chemistry: Bioleaching using acidophilic bacteria to reduce chemical consumption .
• Market Expansion:
  • Niche Applications: Tellurium-based topological insulators and phase-change memory materials (e.g., Te-based switches) are emerging high-value markets .
  • Regional Growth: China and India will lead in PV recycling, while Europe focuses on semiconductor-grade tellurium .

Conclusion