1. Closed–Loop CRT Glass Recycling Alternatives
TECHNICAL UNIVERSITY OF CRETE
Department of Environmental Engineering
Laboratory of Toxic & Hazardous Waste Management
Closed–Loop CRT Glass Recycling Alternatives
E. Gidarakos, E. Dimitrakakis

2. Overview CRT Make Up & Composition Current Indian Practices
Hazards Involved
CRT Recycling Methods
Quality Requirements
Conclusions–Recommendations

3. CRT Make Up & Composition
4 different glass types: panel, funnel, neck & solder

4. CRT Make Up & Composition
In principle there is no difference between CRTs of TV sets & computer monitors.
Panel (Screen): high levels of BaO & SrO, ~2/3 of total CRT mass. Nowadays: shift to Pb-free panels
Funnel: up to 25% PbO, ~1/3 of total CRT mass
Neck: up to 40% PbO
Solder (Frit): up to 85% PbO
Mixed CRT glass: 5% PbO, 10% BaO & 2% SrO on an average
Glasses by different manufacturers may well differ in composition (>50 compositions)
Approximate Pb content of the main colour CRT glass components

5. CRT Make Up & Composition
Non-Glassy Parts:
Ni-Fe Shadow Mask (inside the CRT)
Steel anti-Implosion Frame
Electron Gun
Deflection Yoke (Cu)
Coatings:
Phosphor Fluorescent Layer
Al Film
Graphite Layer (funnel outside)
Iron Oxide Layer (funnel inside)

6. Current Indian Practices
Mainly 2 stakeholders are involved in CRT handling:
Dismantlers (very small informal enterprises), which practice manual TV & monitor disassembly
Re-gunners (small informal units with semi-skilled workers & rather sophisticated equipment)
Functional CRTs sold for re-gunning (~½ of appliances) & used for the manufacture of TVs for local brands and videogame screens
A defective CRT is manually hammered to recover the iron frames. Broken glass is then:
Simply dumped, or
Sold to 2nd-rate glass manufacturers (~0.02$/kg)

7. Current Indian Practices
Facts reported:
Current practices do not take into account neither the hazardous substances contained in the coatings, nor in the glass itself
The glass fraction creates little economic incentive, as the material is very cheap & cannot be used for high quality products without better separation techniques
In terms of volume, however, the glass fraction outweighs all other material flows
Motivation for the present study was created by these facts

8. Hazards Involved
Main environmental concern: PbO, and (to a lesser extent) BaO & SrO
Landfilling: heavy metals concentration in leachate may occur, which can further contaminate groundwater
Glass particle size reduction results in increased extraction level
CRTs constitute a large source of Pb in MSW
Colour CRTs are hazardous waste when discarded
CRT hammering → glass dust inhalation (Pb & Ba)
Cuts in case of implosion may occur

9. Hazards Involved
The phosphors coating contains heavy metals & rare earth elements (Cd (in old CRTs), Zn, Y, Eu etc.)
These substances are very toxic, posing hazards for those in improper manual CRT handling, by contact or inhalation
Note that CRT glass is classified as hazardous under the European Waste Catalogue

10. CRT Recycling Methods Panel/Funnel Separation Techniques
Closed-loop recycling: use of a secondary raw material in the production of the same product as it was before, in this case funnel or panel glass. In principle, the reuse of end-of-life CRT glass is possible for the production of both
Critical Phase is the Accurate Separation of the glass fractions
There is no tolerance for solder or funnel remains with panel
There are only few methods reported to be able to achieve this
Panel/Funnel Separation Techniques
Heating Wire: small-medium quantities, low invest
Diamond Saw: large quantities, high invest
Laser Cutting: large quantities, high invest

11. CRT Recycling Methods

12. Note that in any case workers must be protected from exposure to dusts
CRT Recycling Methods
All Coatings/Contaminants must be removed:
Fluorescent Coating Removal
Washing
Vacuum Suction (most common): simple, easy, special filter required
Panel aluminum layer removal
Funnel graphite & iron oxide layer removal
Removal of all stickers, pins, other non-glass parts…
Fluorescent coating destined for hazardous waste landfill (Y or Eu etc. recovery under research)
Note that in any case workers must be protected from exposure to dusts

13. CRT Recycling Methods
Process Flow Chart

14. Quality Requirements Critical Points:
Accurate Panel/Funnel Separation (again!)
The only waste CRT glass that can be used in the manufacture of new screens is separated panel
Mixed glass can be used in funnel production (only), but separated is strongly preferred. Constraints on using waste glass in funnels production are less.
All coatings/contaminants must be removed

15. Quality Requirements Critical Points:
Note that even if waste panel glass is free of chemical & physical contamination, there are still barriers to its use in the manufacture of new screens, if it is of a significantly different chemical composition from the new glass.
Final product homogeneity (different compositions depending on manufacturer) demands & solutions:
Knowledge of mean chemical lot composition required
Very small variations in oxides content (<0,2%)
Rejection of incompatible glass (brand identification)
Large lot blending (more feasible)
Inconsistencies may result in melter shut-down & batch rejection

16. Quality Requirements Glass Industry Requirements: Limitations:
Consistent Cullet Quality & Quantity
Certain feedstock specifications, e.g.:
Some glass manufacturers accept only non-crushed glass
Recycled Glass Packaging & Transportation
Limitations:
Quantity incorporated in the manufacturing process will vary between different manufacturers, so that no change in produced glass properties occurs
Max. amount of cullet (separated panel) that could be used in the production of new panel glass: ~30%
Max. amount of cullet (separated funnel) that could be used in the production of new funnel glass: ~55%

17. Conclusions–Recommendations
There is an imperative need for the adoption of these efficient CRT recycling alternatives, which will
Mitigate the hazards involved in the present processes
Greatly improve the added value of the recycled glass
Increase profitability of this waste stream
Future Work:
Awareness building among interested entrepreneurs
Training Packages’ Development
Economic feasibility confirmation
CRT glass industries capacity & capability assessment

18. Conclusions–Recommendations
Additional Remarks:
Closed-Loop recycling can provide the recycling sector with an efficient channel for obsolete CRTs in the short- or mid-term
More research is needed for the use of waste CRT glass in new open-loop applications, which could absorb significant amounts of it in the long run
In addition, Pb & Cu smelting operations can also use waste CRT glass as fluxing agent, and cannot be therefore ignored. The capacity of each smelting operation needs to be assessed.

19. Thank You for Your Attention!

20. Questions