Glass Recycling Explained

Glass is manufactured on a massive scale because it is used in so many different products that we all use in everyday life. No matter how or what we use glass for, most of it can and should be recycled which is most easily done by putting it a recycling bin but then what happens to it? Let’s find out all about the glass recycling process.

Stage 1 - Disposing of your glass

The first stage of the recycling process begins with you and this means you must separate glass items into the appropriate recycling bin for collection or to take to a local recycling facility or drop off point. Since glass is very breakable, it should never be mixed with other materials that are being sent for recycling.

Stage 2 – Collecting glass for recycling

When waste collection wagons or recycling companies collect the glass recycling bins, they are then taken to a recycling centre to be stored before the next stage of the process.

Stage 3 – Inspecting the glass

Every glass item or product that is sent for recycling has to be inspected to ensure it doesn’t contain any hazardous substance or is contaminated in any way.

Stage 4 – Sorting the glass

Before the glass enters the recycling process, it must be sorted so that any minor or major contaminants that are not made of glass and the types of glass that cannot be recycled can be removed. This includes ceramic glass, mirrors and Pyrex as well as light bulbs and window frames. During this stage, the glass is also sorted into different colours, for example clear, green, brown and non-brown.

Stage 5 – Breaking up the glass

Once the glass has been sorted it is then ready to be broken down to make it easier to recycle. This is done using a large machine that has many hammers to break the glass down into very small fragments before it enters the stage of the recycling process.

Stage 6 – Screening the glass

The glass fragments now need to be sorted into size so are now passed through a mechanical screening machine called a trommel or a rotary screen. As the glass passes through the revolving screens, any labels or adhesive paper that are still present are pushed out by a fan into a separate chamber and this material is then sent for recycling at an appropriate facility so nothing is wasted.

Stage 7 – Drying the glass

After screening, the glass particles must be dried in a machine that uses vibration to move the glass along a bed drier where the air is heated to 87.78° centigrade. This process also removes any remaining glue on the glass which is then sucked away by the vacuum system on the top of the bed drier.

Stage 8 – Rotary screening the glass

The clean and dried glass particles must now be screened into various sizes using screens that have a different size mesh. Recycling plants can change the screens according to the size of glass particle required for manufacturing purposes.

Stage 9 – Pulverising the glass

Any glass that could not pass through the rotary screener is put into a pulveriser that uses 36 hammers to further reduce the size of the remaining particles so that they can be returned to the rotary screening machine.

Stage 10 – Screening the glass again

This stage again involves using a rotary screen but this time it is all separated into four sizes that are used for specific purposes.

Stage 11 – Classifying the glass

The glass particles are classified according to the cullet size which can be pebbles or sand or powder. Using cullets to make new glass products consumes 25% less energy than making new glass from scratch which makes recycling glass even more eco-friendly.

Stage 12 – Recycling the glass

The different sizes of glass cullet are now ready to make new glass items and products such as glass jars and containers, fibreglass and additives for other processes.

Why you should recycle glass

Because glass is unable to decompose, if it isn’t sent for recycling it will just remain in landfill for years. In fact, experts have calculated that for an ordinary glass bottle to break down completely in landfill would take one million years.

It can take as little as one month for glass to pass through the recycling process and be made into a new product. Recycling just one glass bottle means that sufficient energy is saved to power a 100 watt light bulb for four hours or a television or computer for 30 minutes. For every tonne of recycled glass that is collected, 10 gallons of oil are saved leading to a reduction of air pollution by up to 20%.

Recycling just one tonne of glass can save the use of:

  • 410 lbs of soda ash
  • 1,300 lbs of sand
  • 380 lbs of limestone
  • 151 lbs of feldspar
  • 2 cubic yards of landfill area
  • 42 kilowatts of electricity