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A bed of glass particles at an industrial recycling facility
Recycling News

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Glass Recycling Process

 by Jack McLellan,

How is Glass Recycled?

Did you know that most glass is 100% recyclable? Like steel, glass can be reused infinitely, making it a sustainable material. Glass recycling has existed for centuries, starting as early as the roman empire. Thankfully, modern recycling technology has made the glass recycling process more streamlined than ever.

Glass is manufactured from silica, soda ash, limestone, or recycled glass (cullet). These materials are heated, melted, and then shaped using a glass mold to make things like bottles, windows, and more. 

After you throw a glass bottle or jar in the recycling bin, it undergoes a complex process to be broken down into cullet for eventual reuse. 

What Glass Can’t Be Recycled?

While recycling facilities can recycle most glass, it is worth noting that not all glass is reusable. While this list includes a general guideline on what can and can’t be recycled, check your local recycling guidelines, as they may differ.

An infographic about Glass Recycling Dos and Don'ts.Glass materials that can be recycled:

  • Glass bottles
  • Glass jars
  • Monocolor glass

Glass materials that can’t be recycled:

  • Broken glass
  • Mirrors
  • Window glass
  • Heat-resistant glass
  • Ceramics
  • Dirty glass
  • Lightbulbs
  • Drinking glasses
  • CRT TV screens

Rinse your bottles and jars to remove contaminants and residue from food and drinks. This will make recycling the glass more manageable and keep bugs out of the glass.

What Are the Benefits of Recycling Glass

Like other forms of recycling, glass recycling is good for the environment. Compared to being produced from scratch, making glass from cullet reduces air pollution by 20% and water pollution by 50%. In addition, recycled glass uses 40% less energy than producing new glass.

Of course, recycling glass also reduces the amount of waste sent to landfills. Landfills will move closer to urban spaces if we continue to throw away recyclable materials like glass and plastics.

How is Glass Recycled?

Glass undergoes several steps to be reduced to cullet and reused. We’ve outlined the standard glass recycling process:


Glass bottles and jars are thrown in the recycling bin and then collected by trucks and sent to recycling facilities.


Once the glass arrives at a glass recycling facility, it is separated by color and type. Glass can not be mixed with different colored glass because they are made using different components. Equipment like color sorters are fed using distribution conveyors to optimize the sorting process. Contaminated glass, cullet, and other glass that can’t be recycled are disposed of during this stage.

In single-stream recycling facilities, the glass is usually separated from other recycled materials like cardboard and paper early on, as it can break and become a contaminant, which is a significant source of difficulty for single-stream facilities that accept glass.

Cullet Production

The glass is transported to be crushed and ground into fine bits. Sometimes water will be added during this process stage to stop tiny glass particles from entering the air.


The crushed glass is then sent through trommel screens. Items like paper or cardboard are blown out of the screen by air. The trommel rotates and strains the crushed glass through its screen.

Bed Drier Fluidization

Glass is moved through a drier via vibration and heated to about 190 degrees Fahrenheit. The heat burns off any remaining sticky contaminants on the glass, such as glue or sugar.

Primary Rotary Screening

A screen filters out the smaller pieces of glass while transporting larger glass pieces out for further crushing. Secondary screening can begin once the larger pieces of glass are crushed enough to fit through the primary screen.

Secondary Screening

The cullet is then sorted based on size. Depending on the size of the cullet, it is used for different applications. Cullet can be used for glass production, fiberglass, additives in metal foundries, filtration systems, and more.

Optimize Your Glass Recycling Process with GK

The process of recycling glass moves much more smoothly when you’ve got efficient glass recycling equipment built to last. As glass recycling gains traction in the U.S., get ahead of the game with reliable equipment like General Kinematic’s Glass Cullet Conveyors. To learn more about GK’s glass recycling solutions, contact our experts today.

Jack McLellan

Marketing Coordinator

Jack specializes in creating compelling digital marketing content such as social media, blog posts, newsletters, and more. He works with General Kinematics industry experts to develop educational content for the foundry, recycling, mining, and aggregate industries.