Challenges and opportunities in glass recycling and re-use

A partnership with the NYS College of Ceramics and the NYS Department of Environmental Conservation

Stuart Yaniger

Department of Glass Science, Alfred University

Challenges and opportunities in glass recycling

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November 16, 2023

Alfred University and NYS College of Ceramics

• Alfred University, a private liberal arts university, has long been a worldwide leader in glass and ceramic engineering
• Roughly 2,000 students
• NYSCC is a statutory college within the AU campus founded in 1900

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Inamori School of Engineering

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NYS DEC and Alfred/NYSCC Projects

• Techno-economic assessment (TEA)
• Material flow & economics
• Life cycle assessment
• Environmental impact of stream paths
• Recycle glass quality
• Sources, sorting, cleaning
• Novel sinks
• Non-melting: concrete, soil

• Wine bottle washing, reuse�
• Foamed glass for seawall�
• Retroreflective beads for DoT
• Signs, road markings, architectural coatings�
• Value-added from mixed waste streams�
• Atomistic Modeling to optimize melt behavior

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Challenges and opportunities in glass recycling

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AU solutions along the lifecycle

• Potential for Improvement

New Products

Sorting

Non-glass has to be removed and colored glasses are sorted

Processing

Glass is crushed into cullet

Beneficiation and Co-Extrusion

Further contaminations is removed

Melt Technologies

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But Let’s Start at the Beginning: What is Glass?

• Crystalline SiO₂ (quartz)
• Periodic arrangement of atoms

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What is Glass?

• Glassy SiO₂ (silica)
• No long range arrangement
• Melts at high temperatures, 1700 °C (~3100 °F)

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What is Glass?

• Commercial Glass is soda-lime silicate (SLS)
• Introduction of soda ash (sodium carbonate) and limestone (calcium carbonate) lower melting temperature 1400-1500 °C (2550-2700 °C)

2-D model of soda-lime silicate glass ¹

• Melting with cullet (recycled glass) reduces temperature as low as 1250 °C (2300 °F)

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Recycling: Challenges

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Material Recovery Facilities (MRF)

New Products

Sorting

Non-glass has to be removed and colored glasses are sorted

Processing

Glass is crushed into cullet

Beneficiation and Co-Extrusion

Further contamination is removed

Melt Technologies

Transportation

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I have glass, now what?

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Alfred/DEC Project: Modeling the Flow of Glass

• Recycling Centers in NYS are well known through Glass Coalition
• https://www.glassrecycles.org/industry-tools-1/glass-map/
• Assumptions:
• Lowest cost solution is realistic solution
• Population density is proportional to glass waste production

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Waste Glass

Landfill

MRF

Factory

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Modeling the Flow of Glass

• Model on a per zip code basis
• We built databases of:
• Zip code and population
• Recycling centers capable of handling glass recycling
• Factories in NYS that recycle glass

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Modeling the Flow of Glass

• Predicted Recycling Percentage ~ 30%
• Accepted Recycling Percentage from NYS is ~34%

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November 16, 2023

Modeling the Flow of Glass

• Predicted Recycling Percentage ~ 30%
• Accepted Recycling Percentage from NYS is ~34%

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Recycled Glass Categories

Clean single color SLS

Clean multicolor SLS

Whole Bottles

Working with local wineries for reuse

Dirty SLS

Specialty Glass

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Recycling from household use

No easy way of decoloring glasses, so there are 2 options:

(1) good sorting

• WHITE: ONLY colorless glasses in the container for white glass
• BROWN: iron colored (redox equilibrium) only brown glass�and clear glasses
• GREEN: all green, blue and ambiguous glass colors�green can compensate best for color mismatched without deviating form the wanted color after recycling

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• TODAY AUTOMATED separation of mixed recycling goods and even color sorting:

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(2) re-use for non-color-sensitive products (e.g. insulation glass wool, foam)

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Challenges – Cost Driven

• Many MRF are spread out
• Is the cost of transportation worth the benefit?
• Key factor in why US lags EU

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Centralized vs Distributed Networks

Higher Cost = Higher Yields

Environmental Tradeoffs – emissions

Economic Tradeoffs - labor

• Sinks shrinking
• 1967 40 container glass companies, 112 plants
• 2018: 17 container glass companies, 54 plants
• Cost Benefits
• Requires less energy to remelt cullet

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• Impurities
• CSP: ceramics, stone, porcelain/chinaware
• Ferro and non-ferro metals
• Special glass types (like quartz glass, glass ceramics, lead glass, opal glass)
• Organic waste: paper, plastic, glue residues
• Fine powders

Challenges

• Color composition of the cullet
• Moisture content
• Redox state

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Accumulation and Contamination

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• Glass can be recycled an infinite amount of times if done appropriately
• Without investing some cost, there is not going to be any utilization
• Glass is heavy, reducing the amount of transportation increases utilization
• $5-$20 per ton to transport
• Purity and size of glass also drives cost

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Challenges – Cost Driven

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Once We Have Glass, What Do We Do?

• Hot top melting – continuous melting
• Uses natural gas on top and electrodes in the melt

• Change to oxygen-hydrogen gas

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• Cold top furnace – no gas on top (all electric)

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Current Melting Practices

Fuel Based Furnace

Electric Furnace

Pros:

• Low cost
• Longevity
• High Melting Temperatures

Cons:

• CO₂ Emissions

Cons:

• Shorter Life Span
• Lower Melting Temperatures
• High Electricity Cost
• Larger Mechanical Wear

Pros:

• No CO₂ during melting

Figure 1. “Float Glass Furnace.”

Figure 2. “All Electric Furnace.”

Images Courtesy of Horn Industries

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Hydrogen as an Alternative

• Hydrogen melting can lead to water interactions which impact the glass structure.

• It is important to understand whether these mechanisms will impact fracture behavior.

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Alfred/DEC Project: Melting – Simulations

• Simulations provide atomic scale details of structure and properties of glasses
• Complement and supplement experimental approaches
• How glasses melt is poorly understood, especially on atomistic scale
• Insight into cullet melting mechanisms to optimize re-using glass
• Help determine how to remove elements such as lead or rare earth prior to use
• Optimization of extraction mechanisms

Lead: Dr. Alastair Cormack

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Melting - Simulations

• Container glass is made of about 30-40% recycled cullet
• Goal: to incorporate larger amounts of cullet and still get a homogenous glass without inclusions

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Lead: Dr. Alastair Cormack

• Create atomic scale structures of soda-lime-silicate glass surfaces
• Determine interaction between difference surfaces, bulk and powder to optimize batch components vs. cullet
• Put two surfaces together:

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Alfred/DEC Project: Avoiding Remelting: General Approach to Developing New Sinks

• Primarily soda-lime silicate glasses – with mixed-waste tolerance
• Large scale production: Microbeads, foam, cement, artificial soil for micro-nutrients
• Potential for multiple locations at low levels: Cement/concrete, glass landscaping
• Low temperature processes for smaller scale production (cold sintering)

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New Products - Microbeads

Microbeads

Retro-reflective – Other optical properties

Cement, Agricultural/Consumer

Hollow Glass MicroBeads – MicroSpheres - MicroBalloons (HGMs)

Porous Glass Microspheres – High-Temperature Microspheres.

Porous surface – Solid Microsphere

Porous surface – Hollow Microsphere

Functionalize Surface

The North American microspheres market is growing at a CAGR of > 12% (2018-2023)

United States – 85% of the market

Major Players:

• 3M
• Potters Industries LLC (Cranton)
• Momentive

Others:

• Mo-SCI
• Ceno Technology (Buffalo)
• Hillcrest Ind (Attica)

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Danielle Perry

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November 16, 2023

New Products: Synthetic Soil

• Glass contributes silica (via silicic acid) to plants�
• Enhanced toughness of leaves, stems, and fruit�
• Increased soil albedo for faster ripening�
• Preliminary data suggests green glass is best (convenient!)�
• Working with several prestigious Finger Lakes wineries�
• Drastically reduces transportation and handling costs for recycled wine bottles

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November 16, 2023

Ion-Exchange

• Ion-exchange can be used at moderate temperatures to remove harmful sodium and incorporate potassium for soil applications

Thanks Elene Taniashvili and Alexander Jonsson

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Leaching

• Certain applications, such as cement use and fertilizers for plant growth, sodium can be detrimental.

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New Products – Foam Glass

Foam Glass – Insulation

• Closed pore structure
• Thermal and sound
• Quality of waste glass is not a concern (non-color sensitive)
• Better mechanical properties compared to fiber glass

sample from

Aalborg University, Denmark

Lead: Dr. Bill LaCourse

Alfred approach:

1. Blowing agent is water as NaNO₃

- No organics or CO₃^-

2. Aggregate for cement via pellets rather than boards

Emphasis on cement - aggregate

Decomp. near (800 °C)

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Alfred/DEC Project: Developing Reactive Concrete

A World Without Waste

• Work from University of Nevada has proposed the criteria for sea wall infrastructure
• Islam, Mohammad Shahidul. Performance of Nevada's aggregates in alkali-aggregate reactivity of Portland cement concrete. University of Nevada, Las Vegas, 2010.
• By adding additional criteria for our foam design, we’re able to design reactive seawater aggregate
• Testing to begin in Long Island

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Take Aways

• Understanding melting can greatly increase efficiency, reduce CO₂
• Trying to improve sorting methods for MRF; cost and contamination are key issues
• Determining potential sinks that do not require quality control may increase the amount of glass recycled
• Increasing sinks that do not require remelt can have significant impact on carbon production
• KEEP RECYCLING!

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The Alfred Team Leaders

• Dean Gabrielle Gausted (PI)
• Professor Bill LaCourse
• Professor Scott Misture
• Professor Alexis Clare
• Professor Collin Wilkinson
• Professor Doris Möncke
• Professor Alastair Cormack

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…and their fantastic students!

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Other Collaborators

3D printing buildings from waste glass

Reuse of solar panel glass

Repairing sea walls with cement using waste glass

CRT recycling

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Thank You!

Stuart Yaniger

Research Associate and Adjunct

yaniger@alfred.edu

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